Aquaculture systems for wastewater treatment seminar proceedings and engineering assessment

[From the U.S. Government Printing Office, www.gpo.gov]

United States Office of Water September 1979
Environmental Protection Program Operations (WH-547) 430/9-80-006
Agency Washington DC 20460
Water
&EPA Aquaculture Systems
for Wastewater
Treatment

Seminar Proceedings
and Engineering
Assessmrent

t:. :::I;�- - I :

COASTAL ZONE INFORMATION CENTER
MCD-67

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EPA 43019-80-006

A QUA CULTURE SYSTEMS FOR

WASTEWA TER TREA TMENT:

Seminar Proceedings and
Engineering Assessment

Robert K. Bastian
Sherwood C. Reed

Project Officers

r
Property of CSC Library

September 1979

U.S. Environmental Protection Agency
Office of Water Program Operations
Municipal Construction Division
Washington, D.C. 20460

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U.S. DEPARTMENT OF COMMERCE NOAA
A(Lb~~ ~COASIAL SERVICES CENTER
l(-~~- ~2234 SOUTH HOBSON AVENUE
ChARLESTON, SC 29405-2413

EPA Comment

This report is one of a series planned for publication by the U.S.
EPA Office of Water Program Operations to supply detailed information
for use in evaluating, selecting, developing, designing, and operating
innovative and alternative (I/A technologies for municipal wastewater
treatment. This series will provide indepth presentations of available
information on topics of major interest and concern related to I/A
technologies. An effort will be made to provide the most current state-
of-the-art information available concerning I/A technologies for
municipal wastewater treatment.

These reports are being prepared to assist EPA Regional Administrators
in evaluating grant applications for construction of publicly owned
treatment works under Section 203(a) of the Clean Water Act of 1977. They
also will provide state agencies, regulatory officials, designers, consulting
engineers, municipal officials, environmentalists and others with detailed
information on I/A technologies.

Harold P. CahillI, Jr.
Director
Municipal Construction Division (WH-547)

SEMINAR PROGRAM COMMITTEE

A number of agencies and groups actively participated in the funding and
planning of this symposium. The individuals representing these groups
on the seminar program committee included:

Cecil Martin, Seminar Coordinator
California State Water Resources Control Board
Sacramento, California 95801

Robert Bastian Tom Inouye
U.S. EPA California State Water Resources
Office of Water Program Operations Control Board
Washington, D.C. 20460 Sacramento, CA 95801

Maurice Bender Allen Knight
Argonne National Library (U.S. DOE) Dept. of Land, Air and Resources
Argonne, IL 60439 University of California-Davis
Davis, CA 95616
Frank Carlson
U.S. DOI Sherwood Reed
Office of Water Research and Technology U.S. Army Corps of Engineers
Washignton, D.C. 20240 Cold Regions Research and
Engineering Laboratory
John Colt Hanover, NH 03755
Dept. of Civil Engineering
University of California-Davis George Tchobanoglous
Davis, CA 95616 Dept. of Civil Engineering
University of California-Davis
William Duffer Davis, CA 95616
U.S. EPA
R.S. Kerr Environmental Research Malcolm Walker
La bora tory California Office of Appropriate
Ada, OK 74820 Technology
Sacramento, CA 95616

B. C. Wolverton
NASA
National Space Technology
Laboratory
NSTL Station, MI 39529

This publication contains an engineering assessment and the pro-
ceedings of a seminar held at the University of California-Davis on
September 11-12, 1979, on the use of aquatic systems for the treatment
of municipal wastewater. Case studies drawn from throughout the United
States are used to illustrate the engineering, design, operation, and
management of various wastewater aquaculture systems, including projects
involving wetlands processes, aquatic plant processes, and combined
aquatic processes. The potential recovery of energy and resources is
also considered.

Sponsored by:

California State Water Resources Control Board
U.S. EPA, Office of Water Program Operations
and
Office of Research and Development
U.S. DOI, Office of Water Research and Technology
U.S. Department of Energy
U.S. Army Corps of Engineers
University of California Extension

CONTENTS

Engineering Assessment of Aquaculture Systems for Wastewater Treatment:
An Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sherwood C. Reed, U.S. Army Corps of Engineers
Robert K. Bastian, U.S. Environmental Protection Agency
William Jewell, Cornell University

Aquaculture Systems for Wastewater Treatment: Seminar Overview . . . . . .
Cecil V. Martin and Tommy T. Inouye, California State Water Resources
Control Board

INTRODUCTION AND OVERVIEW SESSION

Why is California Interested in Aquaculture? . . . . . . . . . . . . . . .
W. Don Maughan, California State Water Resources Control Board

Creating a Public Policy Context for Aquaculture Systems . . . . . . . . . .
Robert L. Judd, Jr. and Malcolm Walker, California Office of Appropriate
Technology

The Federal Role and Interest by EPA's Construction Grants Program in
Aquaculture Systems for Municipal Wastewater Treatment . . . . . . . . . .
James N. Smith and Robert K. Bastian, U.S. Environmental Protection
Agency

The Use of Aquatic Plants and Animals for the Treatment of Wastewater:
An Overview . . . . . . . . . . . . . . . . . . .
George Tchobanoglous, Rich Stowell, Robert Ludwig, John Colt, and
Allen Knight, University of California-Davis

WETLAND PROCESSES SESSION

Session Summary . . . . . . . . . . ..
William R. Duffer, U.S. Environmental Protection Agency

Wetlands Creation for Habitat and Treatment - At Mr. View Sanitary
District, California . . . . . . . . . . . . . . . . . . . . . . . . . .
Francesca C. Demgen, Mt. View Sanitary District

Cypress WetlZands for Tertiary Treatment . . . . . . . ......
Walter R. Fritz and Steven C. Helle, Boyle Engineering Corporation

The Drummond Project - Applying Lagoon Sewage EffZuent to a Bog; An
Operational Trial . . . . . . . . . . . . . . . . . . . . . . . . . . .
William M. Kappel, U.S. Geological Survey

Effectiveness of a Wetland in Eastern Massachusetts in Improvement
of Municipal Wastewater . . . . . . . . . . . . . . . . . . . . . . . ..
Donald A. Yonika, IEP, Wayland, MA

Wetland Tertiary Treatment at Houghton Lake, Mi chigan . . . . . . . . . . .
Robert H. Kadlec, University of Michigan

Engineering, Energy and Effectiveness Features of Michigan Wetland
Tertiary Wastewater Treatment Systems . . . . . . . . . . . . . . . . . .
T. C. Williams and J. C. Sutherland, Williams & Works

AQUATIC PLANT PROCESSES SESSION

Session Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B. C. Wolverton, NASA

Engineering Design Data for SmaZll Vascular Aquatic Plant Wastewater
Treatment Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B. C. Wolverton, NASA

Development of Hyacinth Wastewater Treatment Systems in Texas . . . . . . .
Ray Dinges, Texas Department of Health

A Water Hyacinth Advanced Wastewater Treatment System . . . . . . . . . . .
Dan Swett, Coral Ridge, FL

Water Hyacinth Wastewater Treatment System at Disney World . . . . . . . . .
Andrew P. Kruzic, Reedy Creek Utilities Company, FL

Utilization of Water Hyacinths for Control of Nutrients in Domestic
Wastewater- Lakeland, Florida .....................
E. Allen Stewart III, Dawkins and Associates, Inc.

OTHER AQUATIC PROCESSES SESSION

Session Summary . ..................
Allen Knight, University of California-Davis
Frank T. Carlson, Office of Water Research and Technology

Some Ecological Limits to the Use of Alternative Systems for Wastewater
Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Darrell L. King, Michigan State University

Utilization of Silver and Bighead Carp for Water Quality Improvement . . . .
Scott Henderson, Arkansas Game and Fish Commission

Treated Sewage Effluent as a Nutrient Source for Marine Polyculture . . ..
John H. Ryther, Woods Hole Oceanographic Institute

The Solar AquaceZll System for Primary, Secondary or Advanced Treatment
of Wastewaters ...............
William C. Stewart and Steven A. Serfling, Solar AquaSystems, Inc.

ECONOMICS, ENERGY, AND BY-PRODUCT UTILIZATION SESSION

Session Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
John Colt, University of California-Davis
Maurice Bender, Argonne National Laboratory

Energy Consumption, Conservation and Recovery in Municipal Wastewater
Treatment - An Overview . . . . . . . . . . . . . . . . . . . . . . . . . .
Maurice F. Bender, Argonne National Laboratory

Resource Recovery from Wastewater Aquaculture . . . . . . . . . . . . . . . .
Larry O. Bagnall, University of Florida

Energy from Wastewater Aquaculture Systems ..................
John R. Benemann, Ecoenergetics, Inc.

An Overview of the LegalZ, Political, and Social Implications of Wastewater
Treatment Through Aquaculture . . . . . . . . . . . . . . . . . . . . . . .
Loretta C. Lohman, Denver Research Institute

Economics of Aquatic Treatment Systems ....................
Ronald W. Crites, Metcalf & Eddy

vii

Engineering Assessment
Overview

ENGINEERING ASSESSMENT OF AQUACULTURE SYSTEMS FOR
WASTEWATER TREATMENT: AN OVERVIEW

Sherwood Reed USACRREI, Hanover, N.H.
Robert Bastian US EPA/OWPO, Washington, DC
William Jewell Cornell University, Ithaca, NY

BACKGROUND

The use of aquaculture concepts for wastewater treatment has
received increasing attention in recent years. Systems studied to
date have included both natural and constructed wetlands, ponds,
raceways and other structures based on various combinations of
aquatic plants and animals.
In some cases these systems were not optimized for wastewater
treatment since the principal goal was biomass production or the re-
covery of some other beneficial product. In other cases wastewater
treatment has been the primary objective with byproduct recovery of
secondary importance. Both types have been studied at the research
level, tested at the pilot scale, and in some cases demonstrated as
a full scale operational system.
Some of these systems have shown a potential for reducing energy
requirements and operation and maintenance costs. The incentives
of the Clean Water Act of 1977 provide a strong encouragement for
increased use of such "innovative and alternative" technologies
for wastewater treatment. However, much of the engineering profession,
which is responsible for the design of municipal treatment facilities,
is not familiar with these aquaculture concepts or their capabilities
and limitations.
The purpose of this assessment was to define the current status
of aquaculture technologies and to determine if they are ready for
routine use in municipal wastewater treatment. If they are not ready
for such use the assessment was to recommend procedures for reaching
that goal. This could take the form of further research, demonstra-
tion, or construction of full scale "innovative" systems at selected
locations.
A team of six internationally recognized engineers was retained
to help conduct the engineering assessment. They represented a broad
range of expertise and included both practicing consultants and uni-
versity professors. All were experienced in both research and
design and were knowledgeable regarding biological systems and

innovative technologies. The team included:

Mr. Gordon Culp
Culp Wesner and Culp.

Dr. E.J. Middlebrooks
Utah State University

Dr. Walter J. O'Brien
Black & Veatch

Dr. Edward Pershe
Whitman & Howard, Inc.

Dr. H.G. Schwartz, Jr.
Sverdrup & Parcel & Assoc. Inc.

Dr. George Tchobanoglous
University of California-Davis

This team was organized and directed by Mr. Sherwood Reed, USACRREL
and Mr. Robert Bastian, EPA/OWPO. The basis for the assessment was a
multi agency sponsored seminar entitled "Aquaculture Systems for Waste-
water Treatment" held at the University of California - Davis, on
September 11-13, 1979 (EPA 430/9-80-006). At this meeting research
scientists, operating system personnel and others presented papers on
various projects and concepts relative to aquaculture systems for waste-
water treatment. The final day of the seminar was xeserved for direct
discussion and interchange between the team of engineers and the seminar
speakers. Each member of the engineer team then prepared his assessment
based on the seminar presentations, supplemented by other information
available with general literature. The areas addressed were organized
into three major categories and two team members assigned to each one:

1. Wetland processes - Tchobanoglous & Culp

2. Processes primarily dependent on aquatic.plants - Middle-
brooks & O'Brien

3. Combined processes where more than one element has a sig-
nificant role - Schwartz � Pershe

This overview is based on those individual reports plus a
review and analysis of the available information by the authors of the
overview. This overview is organized in three topical areas with
discussion, conclusions and recommendations presented for each.

WETLAND PROCESSES

For purposes of this assessment wetlands are defined as land

where the water table is at or above the surface for long enough
each year to maintain saturated soil conditions and the growth of
related vegetation. These can be either preexisting natural wetlands
(eg. marshes, swamps, bogs, cypress domes and strands, etc.) or con-
structed wetland systems. Constructed systems can range from creation
of a marsh in a natural setting where one did not permanently exist
before to intensive construction involving earth moving, grading,
impermeable barriers or erection of containers such as tanks or
trenches. The vegetation that is introduced or emerges from these
constructed systems will generally be similar to that found in the
natural wetlands.
Studies in the United States have focused on peatlands, bogs,
cypress domes and strands, as well as cattails, reeds, rushes, and
related plants in wetland settings. A constructed wetland involving
bullrushes in gravel filled trenches was developed at the Max Planck
Institute in Germany. This patented process has seen limited appli-
cation to date in the U.S. A number of projects have been developed
in the U.S. in recent years for restoration or enhancement of wetlands.
These use wastewater but are not necessarily optimized for wastewater
treatment.
Current experience with wetland systems is generally limited
to the further treatment of secondary effluents. In a few cases
primary effluent has been applied in constructed systems. The
removal efficiency of typical pollutants are reported as:

% Removal
Natural Wetland Constructed Wetland
(Sec. Effluent) (Pri. Effluent)

BOD5 70-96 50-90
Ss 60-90

N 40-90 30-98
P 10-50 20-90

It is assumed that bacteria attached to plant stems and the humic
deposits are the major factor for BOD and for nitrogen removal when
plant harvest is not practiced. Plant production can play a more
significant role in nutrient removal when harvesting is included.
With respect to phosphorus removal the contact opportunities with the
soil are limited in most natural wetland systems (an exception might
be peat bogs) and a release of phosphorus has been observed during
the winter in some cases. Based on current experience the land area
being used for natural wetland systems ranges from 30 to over 60
acres per million gallons of wastewater applied. The surface area
for constructed marshes range from 23 to 37 acres per million gallons
of wastewater applied.
The major costs and energy requirements for natural wetlands are
the preapplication treatment, pumping and transmission to the site,
distribution at the site, minor earthwork, and land costs. In
addition to these factors a constructed system may require the instal-
lation of a barrier layer and additional containment structures.

Other factors to be considered are potential disruption of the existing
wildlife habitat and ecosystems in a natural wetland, loss of water
via evapotranspiration for all wetlands in arid climates, the poten-
tial for increased breeding of mosquitoes or flies, and the development
of odor. The major benefits that can be realized from use of wet-
lands include preservation of open space, wildlife habitat enhancement,
increased recreation potential, streamf low stabilization and augmenta-
tion in addition to wastewater treatment.

Conclusions

1. Wetland systems can achieve 'high removal efficiencies for BOD,
SS, trace organics and heavy metals. Their potential may exceed that
achieved in mechanical treatment systems. The specific factors
responsible for these high treatment levels are not clearly under-
stood at this time.
2. Optimum, cost effective criteria are not yet available for
routine design of wetland type municipal wastewater treatment systems
throughout the U.S. The concept has been shown to be viable and
should certainly qualify under current EPA definitions as an innova-
tive technology.
3. The use of constructed wetlands has a greater promise of
more general application. These have potential for better reliability
and process control with a lesser risk of adverse environmental
impact.
4. The use of natural wetlands offers a lesser opportunity for
process control due to natural variability within the system. They
do however have considerable potential as a low cost, low--energy
technique for upgrading wastewater effluents, especially for smaller
communities located in areas of abundant wetlands. The prevention
of adverse impacts on the existing, sensitive wetland ecosystem will
require adequate monitoring and appropriate management practices.
5. Optimization of criteria for constructed wetlands should
result in much lower la-ad and preapplication treatment requirements
as compared to the use of natural systems.
6. 'Health risks for wetland systems are probably not higher
than for conventional treatments assuming that insect vectors are
controlled and that harvested materials are not used for direct human
consumption.
7. The potential for general, routine use of wetland systems,
particularly the constructed type, seems high as soon as reliable,
cost effective engineering criteria are available.

Recommendations

1. Development of reliable engineering criteria will require
additional research and study. These efforts should focus on con-
structed wetlands or on large scale carefully controlled plots in
natural wetlands.
2. Several. large scale natural systems should be installed in
different geographical locations, representing the major types of
wetland systems, with a range of design loadings. These should be

extensively monitored to obtain "real world" operating information
and to serve as the data base for development of design criteria.
This development should be an interdisciplinary effort involving
engineers, scientists and regulatory agencies.
3. A number of constructed wetland systems should be established
concurrently in a variety of geographical settings with other vari-
ables held to the minimum. This should allow development of region-
ally applicable criteria and eventually of generalized relationships
for universal application.
4. Studies of constructed systems should be directed towards
minimizing cost and energy inputs. Therefore, tests with very
dilute or highly treated effluents should be avoided. The focus
should be on untreated wastewaters, primary effluents, and on nutrient
removal mechanisms.

AQUATIC PLANT SYSTEMS

This assessment is based primarily on those systems that use
free floating aquatic plants (macrophytes) for the treatment or
polishing of wastewater. Most of the information that is available
is limited to the use of either water hyacinths or duckweeds and most
of these data are from water hyacinth systems in warm climates. These
systems are all constructed and are generally similar in concept to
wastewater treatment pond technology.
Water hyacinths have been studied in systems treating primary
effluents, as the final treatment cells in multiple cell ponds, and
as an advanced waste treatment step after conventional secondary
treatment. A field scale system for treating industrial wastewaters
is in operation at the NASA facilities in Bay St. Louis, MS and
pilot scale systems are under study at a refinery in Baytown, TX.
A field scale system incorporating duckweed is located in N. Biloxi,
MS. Effluent from this two cell pond system is much better than
secondary quality.
Water hyacinth systems are capable of removing high levels of
BOD, SS, metals, and nitrogen, and significant removal of refractory
trace organics. Removal of phosphorus is limited to the plant needs
and probably will not exceed 50 to 70% of the phosphorus present in
the wastewater. Phosphorus removal will -not even approach that
range unless there is a very careful management program with regular
harvests. In addition to plant uptake the root system of the
water hyacinth supports a very active mass of organisms which assist
in the treatment. The plant leaves also shade the water surface
and limit algae growth by restricting light penetration.
Multiple cell pond systems where water hyacinths are used on one
or more of the ponds are the most common system design. Based on
current experience a pond surface area of approximately 15 acres per
million gallons seems reasonable for treating primary effluent to
secondary or better quality. For systems designed to polish secondary
effluent to achieve higher levels of BOD and SS removal an area of
about 5 acres per million gallons should be suitable. For enhanced
nutrient removal from secondary effluent an area of approximately 12

acres per million gallons seems reasonable. Effluent quality from
such a system might achieve: less than 10 mgIL for BOD and SS,
less than 5 mg/L for N, and approximately 60% p removal. This level
of nutrient removal can only be obtained with careful management and
harvest to yield 50 dry tons or more, per acre per year.
The organic loading rates and detention times used for water
hyacinth systems are similar to those used for conventional stabili-
zation ponds that treat raw sewage. However, the effluent from the
water hyacinth system can be much better in quality than from a con-
ventional stabilization pond, particularly with respect to: SS
(algae), metals, trace organics, and nutrients.
Harvest of the water hyacinth or duckweed plants may be essential
to maintain high levels of system performance. It is essential for
high levels of nutrient removal. Equipment and procedures have been
demonstrated for accomplishing these tasks. Disposal and/or reuse
of the harvested materials is an important consideration. The
water hyacinth plants have a moisture content similar to that of
primary sludges. The amount of plant biomass produced (dry basis)
in a water hyacinth pond system is about 4 times the quantity of
waste sludge produced in conventional activated sludge secondary
wastewater treatment. Composting, anaerobic digestion with methane
production, and processing for animal feed are all technically feas-
ible. However, the economics of these reuse and recovery operations
do not seem favorable at this time. Therefore only a portion of the
solids disposal costs will be recovered unless the economics can be
improved.
The major cost and energy factors for water hyacinth systems
are construction of the pond system, water hyacinth harvesting and
disposal operations, aeration if provided, and greenhouse covers
where utilized. Evapotranspiration in arid climates can be a critical
factor. The water loss from a water hyacinth system will exceed
the evaporation from a comparable sized pond with open water. Green-
house structures may be -necessary where such water loss and related
increase in effluent TDS are a concern. Mosquito control is essential
for water hyacinth systems and can usually be effectively handled
with Gambusia or other mosquito fish. Legal aspects are also a con-
cern. The transport or sale of water hyacinth plants is prohibited
by federal and state law in many situations. The inadvertant release of
the plants from a system to local waterways is a potential concern to a
number of different agencies. Water hyacinth plants cannot survive or
reproduce in cool waters so the concept will be limited to "warm"~ areas
unless climate control is provided. Other floating plants such as
duckweed, alligator weed, and water primrose have a more extensive
natural range but limited data as their performance in wastewater
treatment is available.

Conclusions

1. Aquatic plant systems using water hyacinths can achieve high
removal efficiencies for BOD, SS, trace organics, heavy metals and
nitrogen. The potential can equal, and may exceed that achieved in
mechanical treatment systems.

2. Water hyacinth systems are ready for routine use in municipal
wastewater treatment, at least within the geographical range where
such plants grow naturally. Reliable engineering criteria are avail-
able for the design of systems for treating primary effluent, for up-
grading existing systems, for advanced secondary treatment and for
full AWT.
3. It is unlikely at this time that the costs of plant harvest
and processing will be completely offset by the value of useful
products (eg: animal feeds, compost, biogas, etc.).
4. Water hyacinth systems may be technially feasible even in
northern climates if operated in a protected environment or run as
a seasonal activity. However, this has yet to be shown to be cost
effective for climatic zones where the plants cannot exist naturally.
5. Nutrient removal in water hyacinth systems is more complex
than uptake by the plant alone, but the responsible mechanisms are not
yet clearly defined.
6. Duckweeds are a more cold tolerant plant than the water hya-
cinth. Wastewater treatment experience with these plants is limited and
engineering criteria for routine design are not yet available.
7. Many other cold tolerant aquatic plants exist but their
potential for wastewater treatment has not been evaluated.

Recommendations

1. Further optimization of water hyacinth system design is
possible. This should include: tracer studies of existing systems
to determine actual detention time, the full range of organic and
hydraulic loadings that may be possible, and on mass balances of water
and pollutant materials.
2. Additional study is needed to establish optimum plant 'har-
vesting and utilization techniques and to evaluate alternative methods
for removing additional phosphorus with water hyacinth systems.
3. A study should be undertaken to evaluate the potential for
water hyacinth systems in cooler climates. This should include energy
requirements and overall cost effectiveness. If results of the paper
study are favorable a pilot testing/demonstration program might be
considered.
4. Research and demonstration projects should focus on the use
of duckweed and other plants (especially the more cold tolerant types)
for wastewater treatment. These efforts should include: removal
kinetics for pollutants as a function of detention time, temperature,
plant type, etc.; and the effect of system configuration, season,
benthic materials, and plant harvest on degree of treatment.

COMBINED SYSTEMS
For purposes of this assessment, combined systems are defined
as treatment systems derived from aquaculture concepts that either
contain more than one active aquaculture component in a single unit
or that are combined with other aquaculture or conventional units
to form a process. An example of the former are the experiments at
Woods Hole Oceanographic Institute involving a number of different

marine organisms. Examples of the latter are the Solar Aquacell
System at Hercules CA, the marsh/pond systems studied at Brookhaven
National Laboratories, LI, and the use of fish in the final cells of
wastewater stabilization ponds in Arkansas.
Based upon the results of experimental and pilot testing work to
date, it is clear that both agricultural and municipal wastewater in
treated or partially treated forms can be used in fish culture and
other aquatic protein or biomass production systems. Fin fish such
as Tilapia, carp, gamefish and bait minnows have been very successfully
raised in and harvested from wastewater stabilization pond systems.
Daphnia, shellfish, vascular plants, algae, and other aquatic organisms
have also been successfully produced and harvested. However, it is
not clear that such systems can be optimized for both waste treatment
and protein production purposes at the same time.
Since each concept is unique it is not possible to present a
general summary of performance for "combined systems". The potential
for routine use must also be discussed on an individual basis. For
that reason, the examples cited above are discussed individually
below. Discussion of this limited number of projects is not intended
to imply that there are not other viable systems or combinations, but
space limitations have precluded an exhaustive presentation. It is
hoped that the assessment of these few projects will provide some
general indications or trends regarding combined systems.

Marine Polyculture
Woods Hol~e Oceanographic Institute, MA

This pilot scale, continuous flow system was designed to remove
nitrogen from secondary effluents and at the same time culture marine
organisms that have commercial value. The secondary effluent was di-
luted with seawater and introduced to a system that consisted of
shallow algae ponds, followed by aerated raceways containing stacked
trays of shellfish and then into a final unit for seaweed production.
The algae ponds were designed as the initial nitrogen removal
step. The projected area requirement for this step was comparable
to that required for conventional facultative stabilization ponds.
Problems encountered at this step included inhibition of algae produc-
tion by particulate matter in the secondary effluent, seasonal varia-
tion of algae species and protozoan predation. Some algae species
proved detrimental to shellfish culture and the problem of algae
species control was not resolved. The shellfish experiments with the
American oyster and hard clams indicated slow growth rates and high
mortality. The last unit contained seaweeds for final nutrient removal
with vigorous circulation to keep the seaweed in suspension. Overall
nitrogen removal was 89% with all components functioning but the
overall cost effectiveness was questionable since the shellfish pro-
duction unit was not successful. It appears that nitrogen removal
could be achieved by just a seaweed unit without the preliminary
algae and shellfish steps.

Solar Aquacell System
Hercules, CA

This system was developed through bench and pilot scale testing
of combined aquaculture and conventional technologies. A full scale
system has been recently constructed at Hercules, CA. The system
consists of a two cell anerobic unit, followed by an aerated cell
followed by a final aerated cell covered with water hyacinths and
some duckweeds. An internal feature of all cells are buoyant plastic
strips to serve as a substrate for the growth of attached organisms.
The entire system is covered by a (double layer polyethylene, air in-
flated roof) greenhouse structure. Aeration is provided by submerged
tubing and is low to moderate in intensity.
Performance results are not yet available from the Hercules
system. Based upon pilot units, tested elsewhere, it was predicted
that final effluent quality would be 5 mg/L or less for BOD and SS
if 5 days detention time is provided in the final water hyacinth cell.
The buoyant plastic webbing, with its attached growth is credited with
80% or more of the removal achieved in this cell. Removal of total
nitrogen was about 50% in the same 5 day detention pilot tests and the
water hyacinth plants accounted for only 10% of that removal. Phos-
phorus removal was relatively low (1-2 mg/L removed in 5 days) since
the aquatic plants and organisms are the only pathways available.
The Solar Aquacell concept requires a regular schedule of water
'hyacinth harvest, processing and disposal. The Hercules, CA system
also includes ozone disinfection and a sand filter for final polishing
to maximize reuse potential for the effluent. A functional analysis
of the various elements and components in the system seems to indicate
that the major portion of BOD, SS, and nitrogen removal is provided
by the anaerobic cells and by the attached biomass on the plastic
webs in the aerated cells. The major function of the water hyacinths
and duckweeds may be in shading the water surface to prevent algae
growth. The use of the buoyant plastic web in an aerated pond is a
novel and innovative application. The system can then benefit from
both suspended and attached organisms and the presence of the webs
should reduce or eliminate short circuiting of flow in the system.

Marsh-Pond System
Brookhaven National Laboratory, NY

This 20,000 gpd, pilot unit included an aerated holding cell with
2 1/2 days detention time followed by a 0.2 acre constructed marsh
followed by a 0.2 acre unaerated pond with a partial cover of floating
duckweeds. Effluent from the pond was then applied to the land at a
forested site in a groundwater recharge experiment. This assessment
is not concerned with the land application step or a parallel experi-
ment involving overland flow ahead of another marsh/pond combination.
The system was studied for several years (1975-1978) and received
a wide variation of flow and pollutant loadings. Effluent recycle from
the pond to the head end of the marsh was conducted frequently to
maintain flow in the system. However, neither this recirculation or
the preaeration were controlled in a regular manner. The system was
operated on a year-round basis in the relatively temperate winter
climate on Long Island (average air temperature below freezing 5 months

of the year and the water temperature in the system was 2�C or less
4 months of the year). Reported effluent characteristics averaged
for the period 1975-1977 were:

mg/L % Removal

BOD 21 89
SS 42 91
TKN 11 63
Total P 2 66

The parallel overland flow marsh/pond produced slightly better
results in all categories. Neither system during the period under
discussion could consistantly meet secondary treatment standards for
suspended solids. Both however, provided an excellent, and probably
cost effective preapplication treatment for the groundwater recharge
operation. It is not possible from the published data on the Brook-
haven studies to develop optimum engineering criteria for rational
design since detention times, mass balances, effect of configuration,
season, plant type, etc. were not quantified.

Fin Fish in Stabilization Ponds
Benton, Ark.

There are numerous examples of successful fish culture operations,
with a variety of species, in cooling ponds and wastewater stabiliza-
tion ponds. This assessment will focus on studies in Arkansas where
the effect of fin fish on water quality improvement was evaluated
in controlled experiments.
The preliminary experiments compared parallel 3 cell stabiliza-
tion ponds receiving equal volumes of the same wastewater (BOD 260
mg/L, SS 140 mg/L). The cells in one set were stocked with silver,
grass, and bighead carp while the other set received no fish
and was operated as a conventional stabilization pond. The compari-
tive study continued for a full annual cycle. Results indicated
generally similar performance of the two systems but the fish culture
units consistantly performed somewhat better than the conventional
pond. For example, the effluent BOD from the fish system ranged
from about 7 to 45 mg/L with values less than 15 mg/L obtained more
than 50% of the time. The conventional pond system had effluent BOD
ranging from 12 to 52 mg/L with values less than 23 mg/L about 50%
of the time. Suspended solids were very similar in the effluents
for both systems except in July when the concentration was about
110 mg/L for the conventional pond and 60 mg/L for the fish system.
The second phase of the study was conducted at the same location
with the same wastewater. The six pond cells were all connected in
series and a baffle constructed in each to reduce short circuiting.
Silver carp and bighead carp were stocked in the last four cells and
additional grass carp, buffalofish and channel catfish in the final
cell. No supplemental feed or nutrients were added to the fish culture
cells. Estimated fish production after 8 months was over 3000 pounds
per acre.
Effluent quality steadily improved during passage through the six

cell system. The BOD removal for the entire system averaged 96% for
the 12 month study period. About 89% of that removal was achieved in
the first two conventional stabilization cells. Removal of suspended
solids averaged 88% in the entire system with 73Z of the removal
occurring in the first two conventional stabilization cells. It is
not clear wether the fish or the additional detention time or some
combination is responsible for the additional 7% BOD removal in the
final 4 fish culture cells. The final average effluent concentration
of about 9 mg/L is typical for six cell conventional stabilization
ponds of comparable detention time. It seems very likely that the fish
contributed significantly to the low suspended solids value in the
final effluent (17 mgIL) via algal predation. A value two or
three times that high might be expected for conventional stabilization
ponds.

Conclusions

1. Finfish were effective in providing further treatment in
wastewater treatment ponds. Their major role seems to be suspended
solids control for final polishing.
2. It does not appear that aquaculture components in "?combined
systems'" can be optimized for both protein or biomass production
and waste treatment in the same unit.
3. Systems involving higher forms of animals seem to be less
efficient (at waste treatment), require more land area, or are more
difficult to control than systems primarily based on plants.
4. There is sufficient information available to install fish
culture units in the final cells of stabilization ponds. There is
not enough information available to permit routine design of such
units for wastewater treatment. Specific removal rates and growth
rates and O&YE requirements under different environmental and waste-
water conditions need further definition.
5. Most of the other combined systems discussed here are
either in the exploratory or developmental stage and rational criteria
for their routine design are not available at this time.

Recommendations

1. Development of new concepts in the use of polyculture or
combined systems for wastewater treatment should be strongly encouraged.
The focus should be on high rate, low energy combinations involving
plants and possibly animals or mechanical elements.
2. Further study and evaluation of combined systems is necessary.
This should focus on identifying critical components and on the de-
velopment of engineering design criteria.
3. The most promising concepts should be tested in a variety of
geographical settings to define removal kinetics and develop criteria
for a range of wastewaters and environmental conditions. This would
include the degree of thermal protection and energy required for opera-
tion in cooler climates.
4. Studies should focus on the health effects of the direct use
of animal protein harvested from these systems in human foods. Studies

1 1

should also consider development of alternative products from the
animal protein.

REFERENCES

References are not included in this Overview since it was drawn
from the six engineering assessments published elsewhere ("Aquaculture
Systems for Wastewater Treatment: An Engineering Assessment";
EPA 430/9-80-007; June, 1980) and from presentations at the Davis, CA
aquaculture seminar.

Introduction and Overview
Session
: : : : ::~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

AQUACULTURE SYSTEMS FOR WASTEWATER TREATMENT. SEMINAR OVERVIEW

Cecil V. Martin, Seminar Coordinator and Tommy T. Inouye
California State Water Resources Control Board,
P. 0. Box 100, Sacramento, Calf ornia 95801

Our real interest in wastewater aquaculture started about three
years ago when a number of requests were received asking the California
State Water Resources Control Board to fund aquaculture type treatment
facilities under the Federal Water Pollution Control Act (PL 92-500).
The Clean Water Act of 1977 (PL 92-217) also encourages an examination
of aquaculture treatment as a facet of innovative and alternative (I/A)
technology. The California State Water Resources Control Board (State
Board) staff was requested to evaluate the state-of-the-art and to
advise the State and its Regional Boards on a course of action that
should be taken that would be in the best interests of the people of
the State in regards to the utilization of aquaculture technologies as
well as the expenditure of the grant funds.

in our discussion with the federal EPA and others, we discovered
that a similar need existed for the entire United States. As a result
this seminar was born. It was sponsored by the State of California
and a number of interested federal agencies. It brings together current
projects and workers in the field of wastewater aquaculture. These
proceedings in effect represent the current state-of-the-art on the
topic as presented by the various authors and speakers. A unique fea-
ture of the seminar was the development of an independent engineering
assessment of the material presented. The assessment can be found
elsewhere in this document. The reader is encouraged to read the
original papers, correspond directly with the authors, and develop a
personal assessment as to the status of wastewater aquaculture
technology.

Technical sessions at the seminar were organized in four major
categories: Wetland Processes, Aquatic Plant Processes, Polyculture or
Other Aquatic Processes, and Economics, Energy and By-Product Utiliza-
tion. The major emphasis was on pond-oriented and natural marsh systems
since this is where most of the research and development efforts have
been focused to date.

As indicated by the title of the seminar, the major purpose was
to consider the potential of aquaculture technologies for wastewater
treatment and not as food and fiber production systems, as waste
disposal alternatives, or as mitigation measures of other environmental
impacts of a project. Several polyculture and combined aquatic systems
in various stages of development or demonstration were described. While
systems of this type need further development, they would seem to offer
the greatest promise of combining food production with wastewater treatment.

The presentations at the seminar served to clearly define the
benchmarks of our current knowledge regarding wastewater aquaculture.
These included:

- Aquaculture is being used for all phases of wastewater
treatment from primary through advanced wastewater treatment.
Many current systems use aquaculture components for removal
of specific pollutants such as BOD, SS, metals or nutrients,
or are designed as a polishing step after con~ventional forms
of treatment.

- Aquaculture is an alternative wastewater treatment technique
whose time has come.

- Aquaculture systems can be energy efficient, economical, and
environmentally enhancing under appropriate conditions.

- Aquaculture is not a universal panacea for wastewater treatment.
There are still questions and limitations on applications. The
basic concepts have been demonstrated, but further work is
necessary for process optimization and to define the acceptable
ranges (e.g., geographical difference, wastewater types,
application rates, etc.) for routine use of the concepts.

- Aquaculture systems that were discussed at the seminar appeared
to be cost effective, but in some cases they may be labor
intensive at an unskilled level.

- The terminology involved in wastewater aquaculture need
clarification to avoid confusion and to more clearly define
the major purpose of a particular project. For example,
was tewater has been used in aquaculture systems for the
production of food and fiber, but these same systems were
not necessarily optimized for wastewater treatment.

The presentations at the sminar also helped define what we still
need to know and the opportunities for further optimization. These
included:

- Further definition on the limits of hydraulic and pollutant
loadings and the related reaction kinetics is needed for
process optimization. This would include the influence of:
harvesting, temperature, light, pH, humidity, TDS, plant and
organism types, system depth and configuration, and pollutant
removal efficiencies.

- A more precise definition of the fate of metals, toxic
organics, pathogens and potential disease or nuisance vectors
such as mosquitoes, will assist in selecting aquaculture
concepts and the reuse options for final effluent and
harvested products.

- Routine operation and management procedures for full scale
aquatic systems need further definition. This would include
operator training and certification requirements.

- Legal and institutional restrictions limit the use, the sale,
and the transport of various aquatic plants and fish,
especially nusiance, pest and exotic species. Study is
needed to define the actual impact if these escape from a
treatment system, or to develop an escape proof, fail-safe
system, and/or to use alternative plants and aquatic organisms
for treatment. The geographical range for application of
aquatic systems may be limited without such work.

- The potential for increased benefits exists, but will require
further work for definition of limitations and procedural
methodology. For example, these would include: use of plant
biomass for methane or other energy production, utilization
of harvested animal protein, and recovery of purified water
vapor in greenhouse or covered systems.

Coordinating this first seminar of which we hope will be a continuing
biannual information exchange program on wastewater aquaculture, has
been a very enlightening and pleasurable experience. We were pleasantly
surprised at the interest this topic has generated. The meeting was
attended by approximately 250 people from throughout the nation and
several foreign countries representing many interests and disciplines.

We commend the program moderators and speakers for a job well done.
They kept the seminar on its tight schedule, and the papers as a whole,
were well presented and thorough. The majority of attendees found them
interesting enough to stay through the last presentation!

We would like to extend our thanks especially to Ms. Allison Gotez
and Mrs. Shirley Bell of the University of California, Davis, Conference
and Campus Services for their assistance. Without their patience and
tolerance during our mad scramble to organize this seminar, we would not
have attained the high degree of success, that is evident by the papers
reproduced in this publication.

.17

WHY IS CALIFORNIA INTERESTED IN AQUACULTURE?

W. Don Maughan, Chairman, California State Water Resources
Control Board, P.O. Box 100, Sacramento, CA 95801

INTRODUCTION

The people of California are committed to the cleanup of its
waters and to the maintenance of water quality in the face of
increasing population growth, as shown by its statutes and voter
approval of $875 million of Clean Water Bonds. We want to be
innovative about how we achieve high water quality because conven-
tional wastewater systems have substantial monetary, environmental
and energy costs.

From data on aquaculture treatment systems, use of these systems
in some cases in California appears highly promising. Land avail-
ability and climate factors seem particularly suitable for use of
these systems. California also has the scientific capability for
rapid research and development of these systems from inception to
implementation.

In the immediate future, we see the potential for application of
these systems to small communities. Under the 201 construction grant
program, there are approximately 350 small unsewered communities on
the current priority list. They are prime candidates for systems
which are economical to build and operate.

Further into the future after Federal 201 and Clean Water Bonds
have been used to bring all our major population centers to at least
secondary treatment levels, aquaculture wastewater treatment systems
could be used to expand the capacity of some of the existing
facilities to meet the needs of increased populations. It is expected
that the lack of State or Federal funding of capital expenses will
mean that plants which may be more labor-intensive but less costly
to build than those presently in operation, will become more
attractive.

California is strongly interested in reuse and reclamation of
treated wastewaters which would be furthered by aquaculture systems.

In October 1977, the State Board established an Aquaculture
Section in the Division of Planning and Research. The Section's
responsibility is to evaluate and demonstrate the use of aquaculture
as a wastewater treatment technique and, where practical, to offset
the cost of treatment to consider the culture for production of
aquatic organisms for sale. Although the primary interest of the
Board is in wastewater treatment, disposal, and reuse, all aspects of
aquaculture and mariculture technology are also included in the
Board's program as it relates to beneficial use of waters of the State
and are therefore of interest.

In regard to wastewater treatment, an aquaculture center at U.C.
Davis has been established recently to look at the wastewater treat-
ment processes. In addition, the State Board staff have been working
closely with the City of San Diego for preparation of a workplan for a
1 mgd pilot project using water hyacinths. State Board staff have
also worked very closely with the City of Arcata during the development
of a pilot project to demonstrate the feasibility for using marshes
for wastewater treatment with additional benefits for wildlife.
Construction of this project is expected to begin this month.

In the area of reuse and general aquaculture and mariculture
technology, the State Board has established a project at Firebaugh to
examine the reuse potential of irrigation drain water for aquaculture
of invertebrates and fish. Preliminary results of these studies have
been extremely encouraging but the final evaluation will not be com-
pleted until July 1980. Before aquaculture can be fully accepted, the
engineering and health communities must be convinced that these
systems work in terms of treatment capability and reliability, and
that their operation is within the capabilities of the average plant
operator. In the past, the lack of consistency in reporting treatment
parameters among researchers and serious omissions in data have
hindered acceptance. Further pilot-scale facilities with extensive
control features for operational flexibility have not been used in the
past to determine environmental tolerances, production rates and
changes in water quality associated with the test organisms. It is
hoped that this seminar will help future projects to overcome these
shortcomings in the earliest practicable timeframe.

More research is still indicated. Additional work with aquatic
plants must be conducted in order to evaluate the potential of extending
the geographical and climatic areas for the use of these systems as
well as the potential for increased reliability under controlled
environmental cconditions as afforded by greenhouse covers. Also
developmental research should include utilization of other aquatic
macrophytes with restricted ranges for special application. Up to
this time research has generally emphasized those species with wide-
spread distribution.

Clearly, much information has been developed and will be presented
during the next two days. More data will have to be developed in
order to enable decision-makers to have confidence in aquaculture.

It is our hope that this seminar will be more than an interchange
of technical informtionl more in the sense that all advocates of
aquaculture find the best and quickest way to put this kind of treatment
on a solid foundation so that elected and appointed officials can make
commitments to the process.

CREATING A PUBLIC POLICY CONTEXT FOR
AQUACULTURE SYSTEMS

Robert L. Judd, Jr., Director, Office of Appropriate
Technology, State of California, 1530 - 10th Street,
Sacramento, CA 95814

Malcolm Walker, Environmental Health Engineer,
Office of Appropriate Technology, State of
California, 1530 - 10th Street, Sacramento, CA
95814

If aquaculture systems for wastewater treatment are to be adopted
on a meaningful scale, it is necessary to set goals and orient re-
search efforts toward answering questions that policymakers must ask
before making investments of public funds. Al-though work in progress
is encouraging, there is a disquieting lack of context that may con-
strain future development. The current situation in California as
described here exemplifies both the promise and problems inherent in
aquaculture system implementation.

I'd like to offer some perspectives on aquaculture and the
implementation of alternative methods both here in California and in
other areas. My cormments will address the state-of-the-art froi, a
policy perspective, and then suggest some directions for the future
that could accelerate development.
Many of you in the audience are either students planning to work
in aquaculture as engineers or biologists, or are already working as
professionals in the field. The perspective that I hope to share
with you sheds light on how the decisions are made for funding pro-
jects, and how public policy itself is implemented. They reflect the
kinds of questions that are asked by the Governor and by the State
Department of Finance as they consider whether or not to make invest-
ment decisions in various forms of alternative technologies.
When I was asked to be on this panel I sat down and asked myself
a few questions, then I decided to call a number of experts around
the country to raise the questions with them. My inquiry began by
asking, what do we get from what we already have? Where are we going?
What is the context for the aquaculture development that currently

.23

exists? And I found as I called around that everywhere it is about
the same. California is seen as the leader but there are obviously
good projects in other states as well. The interesting fact is that
in most cases they are run by individuals who are leaders rather than
by institutions that have taken the lead.
As I talk I'd like to focus a bit on the realities of what's
going on, and to point out that the reality is less encouraging than
common perception. Some of the questions that come up are as follows:
How do we implement the technology itself? R~ight now the focus seems
to be primarily on basic research. Aquaculture and wastewater treat-
ment are essentially an "ad-hocracy" rather than a bureaucracy at this
point. As a scientific discipline and as a practical matter, it lacks
organization. It more closely resembles a number of random points
than a series of connected points on a line that has some direction.
I see the situation as one that both reflects the state-of-the-art
while at the same time indicating a need for a joining of forces and
a focus to decide where this research is going, to set targets, to set
goals. What is the public policy outcome of these various projects
in the state? Do we have a target of treatment of a certain amount
of wastewater by a certain period of time? Do we have cost targets?
They don'Ft seem to exist right now.
In talking with various individuals in research or program admin-
istration, I find a common feeling that we're not sure that the right
questions have been asked, that we have an answer without adequately
defining the question at hand. Nevertheless, experimentation goes on.
For example, the Office of Appropriate Technology and the State
Water Resources Control Board worked together to implement the experi-
mental aquaculture center here at the University of California at
Davis. Where is that going? What's the function of it? There will
be nearly half a million dollars spent on aquaculture research here
in Davis in the next three years. What return can the government
expect on its investment?
Preliminary cost and energy analysis show aquaculture to be very
cost effective when compared with a conventional wastewater treatment
facility of 1 million gallons a day. Capital cost comparison for an
IMGC plant between aquaculture, primary and water hyacinths and chlo-
rination, and conventional treatment, activated sludge and chlorina-
tion, show a cost saving of $682,500 or 142 percent. Operation and
maintenance cost show a further saving of $22,500/yr. while energy
savings for aquacultur~e over conventional treatment is 1.03 x 106
kWh/yr. or 47 percent. Such savings are substantial for small commu-
nities where the wastewater treatment facility may be the largest
energy user in the community. These analyses, though encouraging,
are dependent on good design criteria, efficient harvesting methods
and ease of operation. If we are to stay in this business then we
must strive to accomplish the goal of developing a cost effective and
energy resourceful wastewater treatment system. Aquaculture is such
a system, but will require initiative and direction.
Other questions arise: What can be done to speed and focus the
work to ensure that there is a public value above and beyond research
successes? Whose realities are we dealing with? That of the biol-
ogist, the engineer, the city manager who faces rising costs in
treatment programs and discharge problems? The consensus is that

there is. a lack of momentum, that if the work remains as it currently
is -- with a few good people doing experimental projects -- that our
effort will not be enough. We will have foregone opportunities that
greater advocacy would have brought us, and we will simply end up three
or five years from now at about the same level of non-implementation
unless a policy focus and a time-related set of goals is developed.
There are numerous barriers that have to be addressed. Legal con-
straints obviously exist. The economic analysis of alternative treat-
ment needs refinement. Life cycle cost methods in this are in
many instances not of a quality to convince a. public body to make an
investment. There are certainly parochial interests involved, such
as the interests of regional boards versus the State board. There
remains a great degree of uncertainty regarding the value of the tech-
nology or the state of development of the technology. Another conflict
exists -- the R&D sector versus the regulatory sector -- in which each
has different interests.
I want to talk a moment about one group that cut through some of
these questions. Many of you have heard of it, and some of you may
have visited the facility that is now under construction in the town
of Hercules, California. Hercules is a small town currently having a
population of about 4,000 people. It's about thirty miles north of
San Francisco. In 1975, the city adopted a general plan which called
for planned growth in an ecologically sound manner. Their plan pro-
jected a population of 20,000 in 1990, up from 4,000 in 1979. Based
on this projection, Hercules faced a problem of what to do with their
additional wastewater. Presently, their wastewater flows to an
adjacent city's -wastewater treatment plan. That plan doesn't have
the capacity to handle the future additional load that will be imposed
by this growth
Hercules therefore was faced with the choice of investing in an
enlargement of the adjacent plant or building their own plant. They
opted for building their own plant. Because they decided to grow
faster than the allowable rate of two percent which is set by the Air
Resources Control Board in California, the city was not eligible for
State and federal wastewater treatment grants. The only way the city
could grow at their proposed rate would be to fund their own system.
They then faced choosing a wastewater treatment system that would
both meet their needs and State discharge requirements. Many treatment
systems would meet the State requirements but few were ecologically
sound, low cost, and resourc~e- and energy-conserving in the local con-
text. Hercules eventually chose an experimental system from Solar
Aquasystems which met their needs and the State requirements; and, at
the same time, provided options for wastewater reclamation and biomass
utilization. The Solar Aquasystem sewage treatment plant is being
constructed with completion of the first module expected in the late
fall of this year (1980). Construction costs are expected to run
about $3.5 million for a 2-million-gallon-per-day plant, or $2 per
gallon compared to $4 to $6 per gallon for equivalent water quality
from an advanced wastewater treatment facility. Operation and main-
tenance costs rnm considerably lower. Depending on the system per-
formance data, reclaimed water may be a revenue-creating commodity.

The important issue to recognize here is that city officials were
willing to take a risk. That they were willing to play what we used
to call "guts ball" -- they'd just get out there, take some calculated
economic risks and some political risks to move the technology ahead.
I suggest that -we need more of that in the State, and that we can have
it if we give our representatives better information an which to base
their decisions.
The present complacent attitude in which aquaculture is mired is
an unnecessary frustration. Why sit back and watch? The hesitancy
on the part of the bureaucrats -- if it works we can claim a victory;
and if not, we can back off from alternatives -- is a disservice to
those of you whose visions and professional lives are invested in this
subject. If you believe in this technology, organize yourselves and
seek better support from the policymakers that provide you. the tools
(dollars and facilities) to make progress. But, as you speak out in
your self-interest, remember that you incur a greater responsibility
to prove the utility and cost-effectiveness of the systems you propose.
Let me move from Hercules to the UC Davis wastewater aquaculture
center. I mentioned before that there were barriers. I'd like you to
understand how bureaucracy works. Much to the credit of the State
Board and to the University, they adopted late in 1977 the concept of
developing an aquaculture wastewater research facility on the campus
here. It went through the budget review process and was approved in
midsummer of 1978. It was provided money for laboratory equipment,
personnel, and for a building in which to do the experiments. About
$375,000 was allocated for the first year, with $150,000 or so for
each of the two following years. It has taken until late spring of
this year, almost a full year, to negotiate overhead rates and to push
a contract through the University and through the Board. Now, seven-
teen months after the money was approved for the facility, we still
have no facility.
This is a problem, fairly typicall suppose, that many people will
face in changing the status quo. I'd have to say that the difference
between the wishful thinking and the reality is that the bureaucratic
slowness drains the momentum from projects. In this case, it looks
like the project will not get off the ground until mid-1980. If there
is to be an incentive and a real commitment rather than rhetoric from
the University and from the State Board, it is important to break
through the log jams on this project, to move faster and to develop a
sustained momentum.
While preparing this speech, I talked to people in Florida,
Washington, and many other states. I say, "Well, what's going on in
other states?" And they say, "Well, not much; we're watching
California." California is seen as the leader. California's Water
Resources Control Board is the best in the country; there's no doubt
about that. Also, the work that is being done at UC Davis by the
scientists here is absolutely top quality.
Yet, if California is the leader; if, in fact, we are setting a
model for others to follow, it is important for all of us to under-
stand what is the quality and nature of that leadership. What really
is the position of the Board itself regarding aquaculture and what
could they do that they axe not already doing? I'd like to give you

a sense of what has gone on there. On March 16, 1978, the Board made
its first resolution concerning alternative wastewater systems. Here's
what it said:

"Therefore be it resolved that the State Water Resources
Control Board does hereby announce its support and en-.
couragement to greatly increase effort and emphasis on
the use of alternative wastewater disposal systems and
that the Board adopt the action plan for wastewater
management systems investigation and implementation in
Calif orni a. "

Fine. Well done. They have a. very good work plan and they have
a small staff working in aquaculture. Recently, however, when the
issue of alternatives were brought before the Board on June 21, 1979,
the resolution was reframed. Listen to the difference in the language:

"Therefore -be it resolved that the State Water Resources
.Control Board does hereby reaffirm its support and en-
couragement to increase efforts and emphasis on the
use of alternative wastewater systems; that the State
Board shall continue to sponsor research and demonstra-
tion projects to advance the knowledge and implementation
of these systems; that the regional boards are encouraged
to issue either waste discharge requirements for experimen-
tal systems or approve a general local agency experimental
program for alternative systems. The State Board is
available for developing alternative programs regardless
of the options selected, experimental alternative systems
are encouraged to be supported."

A strong reaffirmation. Unfortunately, that resolution was
tabled. It was not acted upon. The action plan that currently
exists within the Board, the plan that gives greater stress to
aquaculture than has ever been made before was also not acted upon
at this time. Now that's not meant as a real heavy criticsm, of the
Board. I'm confident that they will act on it. The important point
though is the act and not the good intention. When you table reso-
lutions, you essentially take the wind out of the sails of the
proj ects themselves.
I have a few comments about education. It seems to me that if
we are going to develop advocates for alternative treatment systems
we also have to train people to understand them better. We have to
reduce the amount of uncertainty felt by staff members of the
regional boards. That can be done through training. The same 'Would
hold for training of members of staff at headquarters. Training
opportunities are very limited at this point. 'They could be much,
much stronger.
I have a number of recommendations as I close. The new Board,
as it will be constituted -when the fifth member is appointed, has a
perfect opportunity to speak out in support of practical innovation
and reaffirm its commitment to the use of alternative technologies
in wastewater treatment. Working with practitioners in -the field

and with regional boards, they also have the opportunity to develop4
a context to set goals for aquaculture-based treatment facilities,
and to work together to achieve successful implementation.
Education should receive higher priority, and our State should
provide continuing services to other states which wish to make a
marriage between policy decisions and engineering and technical ex-
perimentation that's been done in the field.
In the discussion of the long-range energy and cost implications
of aquaculture treatment, there is an evaluation which is sadly lack-
ing at, this point; one that answers the question that, if we achieve
the goals that we set, what do we accomplish? Where are we in this
business?
We encourage our Board to continue their good work and to do more
of it.
As you proceed in the conference today, I would suggest that you
consider the technical papers and the experiments that are reported to
you and try to put them in a policy perspective. See how they can
serve t-he kreater public over a period of time. I can tell you that
in deliberations on the State budget -- that until evidence is brought
forth that this is part of a larger plan, that it is going somewhere--
there will be some reluctance to continue to sponsor individual single
projects. At the same time, I can say that the Governor is extra-
ordinarily responsive to implementation of alternatives -when they're
in context. Again and again, whether it be in transportation, energy,
or other issues, when the arguments are presented to the policymakers
so that they can see that it has some long-term payoff for the general
public, for the people of the State, it's sold. It doesn't take
selling; it sells itself. The arguments only come when you can't
answer the question, "Where is it going?"
Thank you.

THE FEDERAL ROLE AND INTEREST BY EPA'S
CONSTRUCTION GRANTS PROGRAM IN AQUACULTURE
SYSTEMS FOR MUJNICIPAL WASTEWATER TREATMENT

James N. Smith, Associate Assistant Administrator for Water
and Waste Management, UJ.S. Environmental Protection Agency,
Washington, D.C.

Robert K. Bastian, Environmental Scientist, Office of Water
Program Operations, U.S. Environmental Protection Agency,
Washington, D.C.

INTRODUCTION

Many of the Nto's consulting engineers and public health
officials have lead municipalities toward the use of capital and
energy-entensive high technologies to treat and dispose of their
increasing volumes of wastewater. These technologies depend heavily
upon the use of equipment, chemicals, and energy in an effort to
maximize their degree of control over the treatment processes while
minimizing land requirements for the treatment facilities. The recent
dramatic increased in cost of energy, raw materials, construction, and
labor will eventually lead even those individuals most dedicated to
the use of high technology for the answers to man's problems to
seriously re-evaluate the potential use of more self sufficient,
managed natural ecosystems in municipal wastewater management systems.

In response to these same pressures, a few imaginative individuals
have been striving to develop more innovative wastewater management
practices, including techniques that harness natural biological
processes to help treat municipal wastewater in a more cost-effective
and energy efficient manner while effectively recycling or reusing the
municipal wastewater and its constituents. While more land intensive,
such natural biological recycle/reuse systems frequently cost less to
operate and use less energy and non-renewable resources. They also
provide the opportunity to enhance the environment through the manage-
ment of natural biological processes that can also help improve
wildlife production and habitat availability, increase recreational
opportunities, produce biomass for use as energy sources, soil amend-
ments, animal feeds, etc.

The Construction Grants Program

Through the municipal wastewater construction grants program of
the U.S. Environmental Protection Agency (EPA), in partnership with
states and municipalities, the funding of municipal wastewater treat-
ment works has grown from a relatively small federal grant program
to become the largest public works endeavor in the world that is
specifically directed to improving the environment (Ruckelshaus,
1976). Under the original federal assistance program, 13,764 projects
totaling $14 billion in eligible costs were provided with $5.2 billion
in grants for the period from 1956 to 1972. The current program
effort, which was launched by the Federal Water Pollution Control Act
Amendments of 1972 (PL 92-500), has assisted over 17,000 projects
costing some $33 billion with over $24 billion in federal grants funded
at the rate of 75% of eligible costs (EPAIOWPO, 1979). Projects
assisted include the planning, design and construction of new treatment
plants, and upgrading of existing treatment facilities, interceptor
and collector sewers, pump stations, corrections to infiltration/
inf low and combined sewer overflow problems, and sludge management
systems.

There has been a clear trend for consulting engineers to rely on
the more traditional and widely utilized conventional wastewater
treatment technologies in the construction of these facilities. The
intent of PL 92-500 and the more recent provisions of the Clean Water
Act of 1977 (PL 95-217), however, was clearly to push toward more
self-sufficient and permanent long term solutions based upon sound
ecological reuse/recycle concepts and to encourage the technological
community to find better and less expensive ways to do the job (Muskie,
1976). In fact, Congress has actively encouraged greater use of
wastewater management practices which result in the construction of
revenue producing facilities that recycle potential sewage pollutants
through the production of agricultural, silviculture, and aquaculture
products.

The I/A Program

The EPA has developed a program to implement the new provisions
of the Clean Water Act, which provide special new incentives for
increased use of innovative and alternative (I/A) technologies to
overcome the impediments facing increased implementation of I/A
technologies through our Construction Grants Program. The new
provisions include increased federal funding for the design and
construction of I/A technologies (increased from 75% to 85%), a 15%
cost-effectiveness preference for I/A technologies over least cost
conventional technologies, 100% funding to modify or replace I/A
technology facilities should they fail, and specific set-asides in
state allotments of construction grant funds to fund only I/A projects.

When Congress passed the Clean Water Act, specific goals were
set forth for I/A technologies. These goals, which have been incor-
porated into the Construction Grant regulations and guidance, focus
on:

o reclamation and reuse of wastewater and wastewater constituents;
o recovery and conservation of energy;
o reduction in costs compared to existing conventional technologies.

Under our Construction Grants Program, EPA has defined "alternative"
technologies as proven methods which provide for reclamation and
reuse of wastewater, productive recycling of wastewater constitutents
or recovery of energy. "Innovative" technologies have been defined
as developed methods which offer an advancement in the state-of-the-
art, but which have not been fully proven in the circumstances of
their intended use. These innovative technologies are to be primarily
directed at achieving increased reclamation, recycling and recovery
of wastewater, beneficial use of wastewater constituents, and energy
recovery as well as cost reduction, reduction in use of resources,
and other environmental benefits.

An area that appears very promising as an I/A technology is the
use of aquaculture systems for municipal wastewater treatment. A
wide range of managed aquatic biological systems have been considered
and investigated for this purpose, including systems involving natural
and constructed wetlands (i.e., marshes, swamps, cypress domes, bogs,
etc.), macrophytes or other aquatic vegetation in ponds, ditches, or
raceways (e.g., water hyacinths, duck weed, algae, reeds, bullrushes,
swagrass, submerged vascular plants such as Potomogeton, etc.), and
various other systems (e.g., polyculture systems, invertebrates such
as Daphnia, finfish such as Tilapia and carp, shellfish, etc.). Such
systems represent a logical extension of the basic land treatment
concepts which have been strongly encouraged by Congress and EPA.
While aquaculture technology has generally been oriented toward the
production of human food rather than the treatment or reuse of
wastewater, the same basic biological principles apply to essentially
all systems designed for the culture of aquatic organism whether the
systems are primarily for waste treatment or production systems
(Duff er and Moyer, 1978).

Aquaculture Alternatives, Their Potentials & Needs

To date there have been relatively few types of projects designed
primarily to treat municipal wastewater through the use of aquaculture
processes. While extensive use has been made of stabilization ponds
which utilize algae to help treat wastewater, only limited use has
been made of managed aquatic ecosystems involving or constructed
wetlands, water hyacinths, finfish and other aquaculture processes as
an integral part of municipal wastewater treatment systems. The
proceedings of an earlier meeting on biological treatment of water
pollution published in 1976 by the University of Pennsylvania (Tourbier
and Pierson, 1976) provides an interesting insite into the long term
potential role of aquaculture and other biological systems for
wastewater treatment.

The functional role of wetlands in absorbing or removing pollutants
has been identified as one of the major reasons for preserving our
Nation's existing wetlands (Horwitz, 1978). Wetlands treatment projects
do exist in Michigan, Florida, California and other states which
utilize the capability of managed wetlands to help treat municipal
wastewater to high levels in an environmentally acceptable, cost-
effective, and energy efficient manner. The systems also effectively
recycle nutrients, organic matter and other wastewater constituents
while improving wildlife habitat, stabilizing stream flows, recharging
ground water, etc. For the most part, however, wetlands have more
frequently served as a handy place to dispose of many dif:Eerent types
of wastes rather than a part of carefully designed and managed waste-
water treatment facilities. Such wetlands disposals practices have in
certain cases actually led to serious problems in existing wetlands.
Their potential for impacting biotic communities in wetlands must be
recognized. Appropriate management practices and adequate monitoring,
as well as proper regulation and control of projects, must be imple-
mented to avoid potential ecological problems from developing.

The future of wetlands treatment systems as an I/A technology for
municipal wastewater treatment should be a bright one. However, it
could be greatly influenced by public opinion as well as the concerns
expressed by government officials and scientists who envision wetlands
treatment systems as the indiscriminant dumping of raw wastes into
wetlands rather than managed ecosystems for treating and recycling
wastewater. Active participation by the various groups interested in
protecting wetlands in the development of projects involving existing
or artificial wetlands for municipal wastewater treatment may help
improve the acceptance of these projects. We need to establish wetlands
management practices that can be applied to the effective and environ-
mentally acceptable use and treatment of municipal wastewater in
existing wetlands as well as guidance on the establishment and manage-
ment of artificial wetlands created primarily to treat wastewater if
these systems are to ever become truly acceptable to the local, state,
and federal environmental and regulatory interests.

While considered to be weeds by many, water hyacinths, duckweed
and other aquatic plants or combination of plants and animals have
been demonstrated to be effective in certain systems required to meet
secondary or greater treatment requirements, nutrient removal, and for
upgrading existing stabilization ponds. They also show great promise
f or treating many industrial wastes. Available land, climatic con-
straints, harvesting problems, special management requirements and
other problems must be faced when utilizing many of the aquatic plants
for wastewater treatment. However, their ability to effectively
utilize solar energy and wastewater nutrients to produce large volumes
of biomass allows one to consider energy and resource recovery from
these aquatic plant systems to offer a possible means of further
reducing the cost of wastewater treatment. Additional potential by-
products from such wastewater aquaculture projects include such
materials as compost, animal feeds or feed additives, processed
products such as protein extracts, bait fish and even processed food
products.

32.

The increased use of natural biological processes such as aqua-
culture systems for wastewater treatment faces special public acceptance
problems and institutional constraints. The lack of acceptance as a
?"proven" wastewater treatment technology by the sanitary engineering
profession and public officials has lead to considerable fustration
where attempts have been made to establish projects. Their lack of
profit opportunities for system designers due to the minimal use of
equipment and engineering design requirements as well as their large
land requirements and heavy dependence upon "1nature"~ have not been
well received by the consulting engineering community for the most
part. How quickly the American public can accept the idea of treating
municipal wastewater by biological systems which also involve the
production of animal feeds, wetlands enhancement or even food production
could also become a major factor in public acceptance. We hope,
however, that the incentives of the new I/A program, as well as the
potential long term savings through lower O&M costs, energy conservation
and recovery, by-product production and utilization offered by waste-
water aquaculture systems, will allow their further development and
use in the coming years.

CONCLUS IONS

The subject of water pollution control and wastewater treatment
can be seen as a problem of biology rather than simply one of engineer-
ing. The scientific basis for treating and the reuse/recycling of
wastewater should give greater emphasis to ecology and the management
of natural biological systems. Neither the technological problems of
designing biological systems nor the political and institutional
constraints facing their implementation should prevent the increased
future use of aquaculture systems for wastewater treatment. Where
these systems can be made to work they should offer effective solutions
to the need for cost-effective, environmentally acceptable, and
energy efficient wastewater treatment and recycle/reuse practices.
In order to assist in encouraging greater use of these aquaculture
systems for wastewater treatment, we need to make sure that the
results of past and ongoing research efforts are effectively applied
to I/A technology projects funded through the EPA Construction Grants
Program.

References

Ruckelshaus, W. D. 1976. "An Environmental Overview," IN: J. Tourbier
and R. W. Pierson, eds., Biological Control of Water Pollution,
University of Pennsylvania Press, pp 340.

U.S. Environmental Protection Agency, Office of Water Program Operations,
September, 1979. "Clean Water Fact Sheet" p. 16.

Muskie, E. S. 1976. "The Economy, Energy, and Clean Water Legislation."
IN: J. Tourbier and R. W. Pierson, eds. Biological Control of Water
Pollution, University of Pennsylvania Press, pp. 340.

Duffer, W. R. and J. E. Moyer 1978. Municipal Wastewater Aquaculture.
EPA 600/2-78-110.

Tourbier, J. and R. W. Pierson, eds. 1976. Biological Control of Water
Pollution, University of Pennsylvania Press, pp 340.

Horwitz, E. L. 1978. "Our Nation's Wetlands" Washington, D.C. GPO.
(An Interagency Task Force Report Coordinated by the Council on
Environmental Quality)

THE USE OF AQUATIC PLANTS AND ANIMALS FOR THE
TREATMENT OF WASTE WATER: AN OVERVIEW

George Tchobanoglous Department of Civil Engineering
University of California, Davis, CA 95616

Rich Stowell Department of Civil Engineering
University of California, Davis, CA 95616

Robert Ludwig Department of Civil Engineering
University of California, Davis, CA 95616

John Colt Department of Civil Engineering
University of California, Davis, CA 95616

Allen Knight Department of Land, Air, and Water Resources,
University of California, Davis, CA 95616

ABSTRACT

Aquatic systems employing plants and animals have been proposed as
alternatives to conventional wastewater treatment systems. The fundamental
difference between conventional and aquatic systems is that in the former,
wastewater is treated rapidly in highly managed environments, whereas in the
latter, treatment occurs at a comparatively slow rate in essentially unmanaged
natural environments. The consequences of this difference are 1) conventional
systems require more construction and mechanization but less land than aquatic
systems, and 2) conventional processes are subject to greater operational control
and less environmental influence than aquatic processes. The major stimulus
for further research into the fundamentals, design, and management of aquatic
systems is the potential for reducing the construction and operation and
maintenance costs for wastewater treatment. The general concepts involved in
the design and use of aquatic systems are presented and the implications are
discussed in this overview.

WASTE WATER CHARACTERISTICS AND TREATMENT

The characteristics of the wastewater to be treated are of fundamental
importance in the selection and design of treatment systems whether conventional
or aquatic, employing plants and animals. Further, the performance, reliability,
and cost of conventional treatment systems have become the standard against
which other treatment systems must be compared. For these reasons, each of
these topics is considered in the following discussion.

Characteristics of Wastewater

The principal contaminants of concern in wastewater are summarized in
Table 1. The addition of chlorine to treated effluent for disinfection may
produce other contaminants of concern such as trihalomethanes, compounds
believed to be carcinogenic. At the concentrations found in domestic wastewater,
the contaminants of greatest immediate concern are biodegradable organics,
suspended solids, and pathogens. Problems stemming from the other contaminants
are of a more subtle, long-term nature and are neither well understood nor
closely regulated at this time. The composition of typical domestic wastewater
before treatment is presented in Table 2. The impact of the constituents
reported in Table 2 on aquatic systems is considered later in this paper.

Wastewater Treatment: Conventional/Advanced

In conventional treatment, the prime objective is the removal of bio-
degradable organics, suspended solids, and pathogenic bacteria (see Table 1).
Conventional systems are not usually designed to remove nitrogen, phosphorus,
pesticides, refractory organics, or heavy metals. Typically, the basic requirements
of a wastewater after receiving secondary treatment and disinfection is that
the BOD (biochemical oxygen demand), suspended solids, and coliform bacteria
(an indicator organism for pathogens) concentrations be less than 30 mg/L, 30
mg/L, and 20 organisms/100 mL, respectively.
In many cases, conventional secondary treatment of wastewater is not
entirely adequate for protection of the aquatic environment. The concentrations
of nitrogen and phosphorus compounds in secondary effluents are often sufficient
to stimulate the growth of algae and other aquatic plants. Depending on pH
and temperature, some of the nitrogenous compounds may be lethal to fish.
Refractory organics and heavy metals may be toxic; they also tend to accumulate
in plant and animal tissue. The effects of the many other contaminants known
to occur in trace amounts in the effluent from secondary treatment systems
are either unknown or not well defined. Advanced treatment methods can be
used to reduce the concentration of these contaminants (see Table 2), but high
cost prohibits their general use. One of the important applications of aquatic
systems may be the further treatment of conventional secondary effluent to
remove nutrients and trace levels of metals, organics, and other contaminants.

THE USE OF AQUATIC SYSTEMS FOR WASTEWATER TREATMENT

To provide some perspective on the use of aquatic systems and before
discussing their design and assessment, it is appropriate to consider the operative
contaminant removal mechanisms, some of the plants and animals that might
be used, the concept of an aquatic processing unit (APU), the types of APUs
that might be used, and the use of aquatic systems in integrated waste
management systems.

Contaminant Removal Mechanisms

The principal removal mechanisms for the contaminants of concern in
wastewater in aquatic systems employing plants and animals are summarized in
Table 3. The removal mechanisms reported in Table 3 have been identified on
the basis of observations of 1) natural systems such as marshes and wetlands,

Table l.--Contaminants of Concern in Wastewater Treatment.a

Contaminants Reason for Concern

Suspended Suspended solids can lead to the development
solids of sludge deposits and anaerobic conditions in the
receiving water.

Biodegradable Composed principally of proteins, carbohydates,
organics and fats, biodegradable organics are measured
most commonly in terms of BOD (biochemical
oxygen demand) and COD (chemical oxygen
demand). If discharged to the environment, the
biological stabilization of these organics can lead
to the depletion of natural oxygen resources and
to the development of septic conditions.

Pathogens Bacteria and viruses capable of causing
communicable disease can be transmitted by water
routes.

Nutrients The nutrients essential for growth include carbon,
nitrogen, phosphorus, and trace elements. When
discharged to the aquatic environment, these
nutrients can lead to excessive growths of
undesirable aquatic life.

Refractory These organic compounds tend to be toxic in
organic relatively low concentrations. Some may also
compounds accumulate in the environment, biologically and
on adsorptive surfaces, concurrent with the slow
decay of these compounds. Typical refractory
organics are surfactants, phenols, and agricultural
pesticides.

Heavy metals Heavy metals are often toxic in relatively low
concentrations. These contaminants are
elemental, i.e., environmentally conservative.
They tend to accumulate biologically and on
adsorptive surfaces. Typical examples are
mercury, lead, and cadmium.

Dissolved Inorganic constituents such as calcium, sodium,
inorganic boron, and sulfate may have to be removed if
salts the wastewater is to be reused.

aAdapted from Metcalf and Eddy, 1979.

Table 2.-Typical Composition of Domestic Wastewater Before and After Treatment
(All Values Except Settleable Solids and Coliform Bacteria are Expressed in
mg/L).

Concentration

Constituent Before After After
Treatmenta Secondary Advanced
Range Typical Treatment Treatment

Solids, total 350-1200 720
Dissolved, total 250-850 500
Fixed 145-525 300
Volatile 105-325 200
Suspended, total 100-350 220 20 <3
Fixed 20-75 55
Volatile 80-275 165
Settleable solids, mL/L 5-20 t0
Biochemical oxygen demand, 5-day 110-400 220 20 1
20 C (BOD, 20 C)
Total organic carbon (TOC) 80-290 160
Chemical oxygen demand (COD) 250-1000 500 80 10
Nitrogen (total as N) 20-85 40 30 2
Organic 8-35 15
Free ammonia 12-50 25
Nitrites 0-0 0
Nitrates 0-0 0
Phosphorus (total as P) 4-15 8 2
Organic 1-5 3
Inorganic b 3-10 5
Chlorides 30-100 50
Coliform bacteria, MPN/100 mL 10 5-109 107 20 <2
Heavy metals c 0.1-2.5 1.3 .8 <0.1
Refractory organics 0.2-7.4 1.4 .2 <0.1
Alkalinity (as CaCO3) 50-200 100
Grease 50-150 100

a From Metcalf and Eddy, 1979.

bShould be increased by the amount in domestic water supply.

CSurfactants, primarily.

Table 3.-Contaminant Removal Mechanisms in Aquatic Systems Employing Plants and Animalsa

Contaminant Affectedb

Mechanism Description

Physical
Sedimentation P S I I I I I I Gravitational settling of solids (and constituent contaminants)
in pond/marsh settings.
Filtration 5 S Particulates filtered mechanically as water passes through
substrate, root masses, or fish.
Adsorption S Interparticle attractive force (van der Waals force).
Chemical
Precipitation P P Formation of or co-precipitation with insoluble compounds.
Adsorption P P S Adsorption on substrate and plant surfaces.
Decomposition P P Decomposition or alteration of less stable compounds by
phenomena such as UV irradiation, oxidation, and reduction.
Biological
Bacterial Metabolism c P P P P Removal of colloidal solids and soluble organics by suspended,
benthic, and plant-supported bacteria. Bacterial nitrification/
denitrification.
Plant Metabolismc S S Uptake and metabolism of organics by plants. Root excretions
may be toxic to organisms of enteric origin.
Plant Absorption S S S S Under proper conditions significant quantities of these
contaminants will be taken up by plants.
Natural Die-Off P Natural decay of organisms in an unfavorable environment.

aAdopted from Stowell et al., 1979
bp=primary effect, S=secondary effect, I=incidental effect (effect occurring incidental to removal of another contaminant).
cThe term metabolism includes both biosynthesis and catabolic reactions.

and 2) laboratory and pilot scale studies of aquatic systems employing one or
more plant and/or animal species. An understanding of these mechanisms is
important because the selection of plants and animals for use in aquatic systems
will depend on the contaminants to be removed and the removal mechanisms
that must be used for their removal. For additional information on removal
mechanisms in aquatic systems see Stowell et al. (1980).
In aquatic systems, the plants and animals themselves bring about very
little actual treatment. The major treatment in these systems is accomplished
by bacterial metabolism. In effect water hyacinth or wetland systems are similar
to a large, slow-rate trickling filter with built-in secondary clarification.

Potential Plant and Animal Use in Aquatic Systems

Potential aquatic plants and animals and their probable role in aquatic
systems are presented in Table 4. When selecting organisms for use in an APU
the designer must consider not only an organism's effect on the aquatic
environment but also its compatibility with the climate and environment of the
design site. Organisms incompatible with climatic and environmental factors
will tend to have unstable populations resulting in fluctuations in aquatic
environmental quality and, ultimately, in APU performance, (i.e., unreliability).
Plants are expected to play a more dominant role than animals in aquatic systems
because of their greater influence on the aquatic environment and greater
adaptiveness to harsh and/or fluctuating environmental conditions. Plants have
significant impact on the aquatic environment by 1) providing a medium for
filtration/absorption of solids and growth of bacteria and 2) affecting gas and
radiation transfer between the aquatic environment and atmosphere.
As reported in Table 4, there are three general categories of plants:
floating, emergent, and submerged. Floating plants have their photosynthetic
parts at or just above the water surface with roots extending below the surface.
With floating plants, the penetration of sunlight into the water is reduced and
the transfer of gas between water and atmosphere is limited. As a consequence,
floating plants in ponds tend to keep the wastewater free of algae and essentially
anaerobic. Emergent plants are rooted in the substrate and have their photo-
synthetic parts extending above the water surface. These plants also reduce
light penetration and gas transfer, but to a lesser extent as compared to floating
plants. Water in stands of emerged vegetation is usually free of algae and
partially aerobic. Submerged plants, including algae, may be suspended in the
water column or may be rooted to the substrate. During the sunlight hours this
category of plants oxygenates the water.
The primary role of aquatic animals may be to further clean-up or "polish"
wastewater treated by removing suspended solids before discharge. Dissolved
oxygen and ammonia levels will be critical in APU's using aquatic animals. The
control of insect vectors, the accumulation of heavy metal and refractory
organics, and their function as bioassay test organisms are important secondary
roles served by animals.

Aquatic Processing Units: A Conceptual Model

An aquatic processing unit (APU) is defined as the assemblage of aquatic
plants and animals (see Table 4) grouped together to achieve a specific treatment
objective (e.g., removal of nutrients and heavy metals). In this context, an APU
is a definable physical entity that represents some discrete step in the treatment
of a wastewater. For example, one or more APU's could be used in conjunction

Table 4.--Potential Aquatic Plants and Animals for Use in Aquatic Systems for
the Treatment of Wastewater.

Organism Probable role and remarks

Floating aquatic plants

Water hyacinth (Eichhornia spp.) Its extensive root system serves as a
mechanical filter and a support structure
for bacteria. Mats of hyacinth attenuate
sufficient light to prevent the growth of
algae. Wastewater leaving hyacinth mats is
devoid of oxygen, typically. Hyacinths will
not winter-over in colder temperate
climates. Water hyacinths are potential
aquatic pests.

Water primrose (Ludwigia spp.) This temperate climate plant is similar to
the water hyacinth, ecologically. The root
system is not as extensive as that of the
hyacinth nor is the floating vegetative mat
as dense. Water primrose attenuate
sufficient light to prevent algae problems.
Wastewater leaving primrose mats may
contain dissolved oxygen. This plant is a
potential nuisance.

Duckweed (Lemna spp.) The root system of this small plant is not
of engineering significance. Duckweed
grows in dense mats that effectively restrict
gas transfer and attenuate light. Ubiquitous
in the United States, duckweed is not
considered a major aquatic pest. Wind can
disrupt duckweed mats. Duckweed can
survive throughout the winter in milder
temperate climates.

Emergent aquatic plants

Cattails (Typha spp.) The submerged portion of a cattail stand
serves as a mechanical filter and a support
structure for bacteria. Algae will not grow
in dense cattail stands, however, water
leaving stands is aerobic, typically. Cattails
successfully winter-over even in harsh
climates.

continued

Table 4 (continued)

Organism Probable role and remarks

Bulrush (Scirpus spp.) Essentially as noted above for cattails
except that stands of bulrush tend to be
more open. Bulrushes may be more adaptive
than cattails to wastewater environments.

Reeds (Phragmites spp.) Reeds are similar to cattails and bulrushes
but tend to grow in comparatively open
stands. In certain situations algae growth
in reed stands could occur. The "hollow
tube" structure of reeds may make these
plants more durable where substrate root-
zone conditions are anaerobic.

Submerged aquatic plants

Algae This broad grouping of unicellular plants
accumulates nutrients and dissolved salts
into settleable algal solids. Photosynthesis
occurs resulting in the release of free oxygen
into the water at the expense of increasing
the BOD of the water. Blue-green algae may
increase the nitrogen content of the water.
In general, algae are aesthetic and biological
nuisances that, if grown, should be removed
in subsequent wastewater treatment
processes. Various forms of algae will grow
throughout the year in open water.

Pondweeds (Potamogeton sp.) The value of pondweeds as support structure
for bacteria is variable from species to
species as is the potential to compete with
and shade out algae. Because these plants
are for the most part submerged in the
wastewater environment, there is greater
inherent chance of upset.

Other possible aquatic plants

Watermlfoil (Myriophyl~iu) All aquatic species have wastewater
Water velvet (Azolla) treatment potential. The answer to the
Coontail (Ceratophyllumn) question "Which to use?" will depend on its
Alligator weed treatment potential and function in a given
(Alternanthera) system. Use of these plants will also depend
Filamentous green algae on whether they will become aquatic pests.

continued

Table 4 (continued)

Organism Probable role and remarks

Aquatic animals

Zooplankton These organisms accumulate algae and other
suspended particulates into a larger sized
particulate. Their presence and effect are
sporadic. The management of zooplankton
populations has proven to be difficult.

Fish
Blackfish Fish serve in a role similar to that described
Carp for zooplankton. Zooplankton retain fewer
Tilapia particles than do most fish. Fish can also
Catfish be used to reduce the vegetative standing
White amur crop, control mosquitoes, or convert plant
Mosquito fish protein to animal protein. Fish populations
are manageable.

Bivalves/clams Clams filter-feed on particulates. To be
most effective, clams should be suspended
in the water column rather than be placed
on the substrate.

Crustacea
Crayfish These omnivores would be useful primarily
Prawn as test and bioassay organisms. They are
Shrimp sensitive to pollutants.

with conventional treatment methods to achieve a desired degree of wastewater
treatment or several APUs could be used together to form an entirely aquatic
treatment system. The conceptual use of APUs to accomplish various wastewater
treatment objectives is illustrated in Figure 1.
The APUs in Figure 1 are arranged so that the application is from least
to most complex. For example, in Figure la, the APUs are used for the removal
of nutrients, refractory organics, and heavy metals. In contrast to this relatively
simple application, the complete treatement of wastewater with an APU is
envisioned in Figure Id. Still more complex is the flowsheet in which an APU
is used for the complete treatment of wastewater (Figure If), including the
removal and disposal of solids handled by the primary treatment facilities used
in flowsheets la through Id.
At present, what little is known about the use of plants and animals for
the treatment of wastewater is related primarily to the removal of nutrients
(nitrogen and phosphorus), refractory organics, and heavy metals from effluents
of conventional treatment systems (Figure la). While this information is of
value, research is needed to define the conditions under which various types and
combinations of aquatic species may be used in various types of APUs to
accomplish primary, secondary, and advanced levels of wastewater treatment
(Figure Ic through If). Because nitrogen and phosphorus removal is not normally
required by regulatory agencies, the greatest potential for aquatic systems is
for secondary treatment.

Types of Aquatic Processing Units

In practice, APUs will contain different types and combinations of aquatic
species, be managed or operated in different ways, and have physical features
that differ with the function of the APU in the treatment system (see Figure
1). The most common types of APUs that have been tried for wastewater
treatment include natural and man-made marshes, wetlands, and various pond
systems in which one or more plants are used. Some more complex aquatic
systems have been developed in Europe, but their use is not well documented
in the literature. Further, a number of these systems are patented. While the
use of a low-energy unmanaged system such as a marsh is desirable, some level
of control may be required because of environmental conditions or to meet
treatment objectives. As an example, a desirable aquatic plant species may not
reproduce in certain climates. In such cases, nursery and planting operations
might become a part of the treatment system. In another case, a particular
harvesting procedure may be necessary to accomplish the treatment objectives
assigned to the APU. In still other cases, the APU environment may have to
be controlled using physical features such as a greenhouse, aeration systems or
artificial substrates. The tremendous variation possible in APUs is a point of
confusion, at present, but, as the performance of selected APUs is defined, this
flexibility in the selection of APU type should become an asset in the design
of aquatic treatment systems for different locations.

Integrated Waste Management Systems

The opportunity to incorporate conventional treatment systems into an
integrated waste management system capable of some resource recovery has
always existed but up till the present time (1979) has not been done routinely.
In conventional treatment systems the principal objective is to reduce the energy

WASTEJl ( _, : i~f ~ .-REUSE
WASTEWATER CONVENTIONAL DISCHARGE
I TREATMENT AQUACULTURE

(b)I

(C)

2.J1 APU

/COARSE SCREENING
(e)l AND COMMINUTION ONLY

(f) I i
PRIMARY I SECONDARY ADVANCED
TREATMENT TREATMENT TREATMENT
_ ,_, ,_,

FIGURE 1

APPLICATIONS OF AQUATIC PROCESSING UNITS
FOR THE TREATMENT OF WASTEWATER

contained in the wastewater (principally in organic compounds as measured with
the BOD test) by respiration and to "harvest" as little biomass as possible, which
is somewhat at odds with the concept of resource recovery.
By the nature of the contaminant removal mechanisms involved in aquatic
systems, there is an opportunity to incorporate these systems into an integrated
waste management system. Although aquatic systems lose energy to respiration,
they gain energy with the growth of photosynthetic plants. An important feature
of aquatic systems is their ability to concentrate energy and nutrients in a more
readily usable form, as compared to conventional treatment systems. Harvested
materials from aquatic systems may contain up to 20 percent solids, whereas
the biological mass removed from conventional systems seldom contains more
than one percent solids.
An example of an integrated waste management and recovery system is
presented in Figure 2. The option of producing a combination of energy or
animal feed is available. As shown, plant tissue from the aquatic systems could
be used, singly or in combination with other solid wastes, as feed for fermentation
or pyrolysis processes that can be used to produce usable energy and to reduce
the volume of solid wastes and sludge. The selection of an operating strategy
for an integrated system will depend on local conditions. It must be emphasized,
though, that the primary purpose of the aquatic system is the treatment of
wastewater and not the production of energy, feed, or other products.

DESIGN CONSIDERATIONS FOR AQUATIC TREATMENT SYSTEMS

Design considerations for aquatic treatment systems are more complex than
those for conventional systems because more variables are involved, many of
which are beyond the direct control of man. Aquatic species must be found
that are capable of removing contaminants while surviving climatic and waste-
water conditions. The design and managerial practices for APUs must be
formulated to provide the environment necessary for the aquatic species to
function as intended. Aquatic systems may have performance reliability problems
that will require special designs. The recovery of resources will also affect the
design of these systems.

Selection of Species

The selection of aquatic plants and animals to be used for wastewater
treatment will be based, to a large extent, on their ability to provide and
maintain an environment in which wastewater treatment will occur. Because
the functional performance of whatever aquatic species are used will depend on
their growth and reproduction, the impact of factors affecting growth and
reproduction such as wastewater characteristics, local environmental conditions,
and APU managerial practices must be known. A number of related factors
must also be considered.

Impact of Wastewater Characteristics. Wastewater characteristics of
concern with respect to the aquatic plants and animals that may be used in
treatment systems are listed in Table 5. In general, aquatic animals (fish,
crustaceans, bivalves) are more sensitive than plants to most wastewater contam-
inants so that some pretreatment of the wastewater may be necessary using
either conventional methods or aquatic plants. When toxic or bioaccumulable
chemicals are known to be present in significant quantities a more specific

COM MUNI TY

Waste water
Source
Metal1, Gloss Seorateo'
Paper GrIt, PE

s wa~~~~~ ther

Rouse

FUTUlRE
tes ~~~~~~~~~~~~~POTENTIAL.
TISSUE AU-TECHNOLOGIES

0~A ITGALTED WASTE MANAOLGEMN SSE

EMPLOYING AQUATIC PROCESSING UNITS

Table 5.--Wastewater Characteristics of Concern with Respect to the Use of
Aquatic Plants and Animals for Treatment of Wastewater.a

Relative Importance Tob

Characteristic Plants Animals

Temperature +++ +++

Suspended solids 0 Emergent species ++
+++ Submerged species

Dissolved oxygen 0 Emergent Species +++
+++Submerged species

N2 supersaturation 0 +

Total nitrogen +++1 +++2

Phosphorus ++1 0

Heavy metals ++2 ++2
++
Boron ++ 20

Salinity ++ ++
2 2
Refractory organics + ++

aAny of these parameters could be limiting over a sufficiently wide range.
The relative importance ascribed to these parameters here is related to the
variation expected in domestic wastewaters.

b 0 No direct influence
+ Influential
++ Important
+++ Critical
1 Growth nutrient
2 Toxicity (depends on form of chemical compound)

characterization of the wastewater may be necessary so that corrective measures
can be taken. The presence of industrial wastes may pose particular problems
for aquatic systems. Injury or death of a plant or animal species may reduce
the treatment performance of an aquatic system for weeks or months, depending
on the recovery or regrowth time of the organisms) affected.

Impact of Local Environmental Conditions. Local environmental conditions
that must be considered include: climatic conditions, substrate characteristics,
and local flora and fauna. Based on a preliminary assessment, it appears that
the climate at the wastewater treatment site may be the major determinant of
the type of aquatic species to be used. Important climatic factors are seasonal
averages and diel variations in the air temperature, the average number of
overcast days, local photoperiod, light intensity, the duration and intensity of
rainfall, the strength and frequency of winds, and the probability of unseasonal
weather. For some plant and animal species a good deal of information exists
about their climatic tolerances, for other species this information is non-existent.
Detailed information on the environmental requirements of aquatic plants
(Stephenson et al., 1980), fish (Colt et al., 1979), crustaceans (Colt et al., 1980b),
and freshwater bivalves (Colt et al., I1980a) is available. The presence or absence
of suitable substrate will be an important factor in the design and operation
of aquatic systems. Local flora and fauna similar to those to be used in the
system should be investigated for predation so that the possibility of system
upsets from indigenous predators can be controlled.

Impact of APU Managerial Practices. Managerial practices for APUs, will
affect and be affected by the species selected. The match between the
environment, as determined by wastewater characteristics and climate, and the
environmental requirements of the selected species needed to optimize their
function in the treatment process will rarely be perfect. Managerial practices
are an additional aspect of the APU concept that, if applied, can create an
environment closer to the optimum for the selected species. Typical APU
managerial practices may include pretreatment of the wastewater, biomass
harvesting, aeration, controlled recirculation, control of residence times, and the
use of artificial substrate and organism support materials.

Impact of Other Factors. Many factors in addition to wastewater
treatment potential, environmental suitability, and species manageability must
be considered when selecting organisms for use in aquatic systems. These
additional factors include the quantity and quality of solids produced by the
organisms and their subsequent disposal; restrictions on the use of organisms
considered aquatic pests; site constraints such as odor production, fog generation,
or vector insect problems; and other site-specific factors. Only under prototype
or full-scale operation will it be possible to evaluate some of these factors.

Design of Aquatic Processing Units

The rational design of APUs is not yet possible because most of the
critical design parameters are either unknown or poorly defined. Additional
information on the design of aquatic treatment systems can be found in Stowell
et al. (1980) and Ludwig et al. (1980). Species-specific information must be
developed about the contaminant removal potential of aquatic plants and animals
as a function of the system constraints. Once the treatment potential of each
species under consideration is known, the design of APUs and aquatic treatment

systems can be undertaken. If combinations of species are to be used within
a single APU, then the interaction between these species must be determined.
When more than one APU is used, the designer must not overlook the possibility
that the effluent from one APU may not be compatible with the organisms of
the next APU. Species-specific and system-specific laboratory and pilot scale
studies will have to be verified by prototype projects to demonstrate how well
aquatic species and systems perform under the varied and often unpredictable
conditions that may be encountered in the treatment of wastewater.

System Reliability

An important design consideration is system reliability (freedom from
failures in treatment). Aquatic system reliability problems stern from climatic
conditions, wastewater characteristics, environmental factors, and disease that
disturb, injure, or kill the plants and animals used for treating the wastewater.
The potential for and consequences of poor system reliability is greater in aquatic
systems than in conventional systems because of greater environmental exposure.
Also, a managed community of higher aquatic plants and animals lacks the
diversity and rapid growth rate of indigenous bacterial populations. Whereas
process upsets in conventional systems last for a matter of hours or days, upsets
in aquatic systems may last from days to months, depending on the extent of
the damage and the recovery time of the organisms affected. In cases where
there is a possibility of relatively long down-times due to climate or the nature
of the wastewater, an alternate treatment system may have to be part of the
aquatic system design. Ways must be developed to control and minimize the
effects of aquatic system process upsets.

Resource Recovery

Because there will be biomass production, the recovery of resources from
aquatic systems offers a possible means of reducing the cost of wastewater
treatment. Harvested biomass could be used in the production of livestock feed,
compost, soil amnmendments, or energy. The economics of resource recovery
will depend on the availability of local markets and uses for the products. Local
consumption of these would reduce the need for expensive processing and transport
equipment. When the economics of a resource recovery operation are favorable,
criteria related to resource recovery should be considered in the selection of
species and in the design systems. Resource recovery should be considered
carefully if its inclusion might diminish the performance or reliability of the
aquatic treatment system.

ASSESSMENT OF AQUATIC SYSTEMS

The success and acceptance of aquatic systems will depend largely on
how well they compare with conventional systems. The bases for comparison
will include treatment efficiency, health risks, and costs. Federal legislation
and administrative policies will also be an important factor in the application
of such systems.

Treatment Efficiency, An Overview

Performance and reliability are important factors in assessing the
applicability of aquatic systems for wastewater treatment. At present,

insufficient data exist to allow a comparison between aquatic systems employing
plants and animals and conventional systems. From an analysis of published
data on water hyacinth and wetland systems (Stowell et al., 1980; Ludwig et
al., 1980) it has been found that these systems remove 80 to 83 percent of the
BOD and SS (suspended solids). The BOD removal characteristics of water
hyacinth systems are presented in Figure 3. The upper value of BOD loading
was 245 kg/ha-d, approximately .5 times the normal loading rate for conventional
wastewater stabilization ponds. The performance capabilities of aquatic systems
appear favorable, especially for the removal of nutrients and trace concentrations
of toxic substances. Reliability may be a major shortcoming of aquatic systems.
Short-term reliability may not be as important as the total quantity of
contaminants removed when considering contaminants with chronic rather than
acute effects (e.g., nutrients, refractory organics, and heavy metals).
Considering both performance and reliability, at least one use of aquatic
systems will be the further treatment of secondary effluents from conventional
systems where higher levels of treatment are required. Other uses may be
discovered as aquatic species growth, materials uptake, and pathology are defined
with respect to the design and operation of aquatic systems. In the initial
development of aquatic systems, it will be important to avoid prejudging the
usefulness of these systems on an all-or-nothing basis.

Health Risks

Health risks for aquatic systems are probably not higher than for
conventional treatment. This is assuming that the animal and plant tissue grown
is not used for human consumption and that potential vector problems are
controlled. The public health hazards of direct consumption of organisms grown
in domestic wastewater are very serious and complicated. State and federal
laws do not allow direct consumption of these products (Kildow and Huguenin,
1974). Their use for animal feeds may be possible if the residues of heavy
metals, trace organics, and pesticides meet state and federal regulations.

Costs

Based on a preliminary analysis, it has been shown that aquatic treatment
systems have lower capital and O&M (operational and maintenance) costs and
use less energy (Tchobanoglous et al., 1979). A cost and energy comparison
between conventional activated sludge and artificial wetland treatment systems
is presented in Table 6 for plant sizes of 0.1, 0.5, and 1.0 Mgal/d. Proper
assessment of the costs of these systems will need to be based on prototype or
demonstration units. In this regard, it will be important to consider the total
cost. This will include the capital and operating costs and the salvage value.
Most of the capital costs of aquatic systems will be in land which should have
a high salvage worth.
With lesser mechanization, lower energy and resource consumption, and
the possibility of some resource recovery, operating costs should be lower for
aquatic systems as compared to conventional systems. Further, the useful life
of aquatic systems should be longer than for conventional systems. For these
reasons, it may be feasible to build aquatic systems with capital costs similar
to or even higher than the costs of conventional systems. The societal benefits
of using labor intensive aquatic systems that may not be cost-effective when
evaluated by current methods should also be considered in assessing the operating

250

DATA FROMI 15 DIFFERENT STUDIES
200 -
* Primary �
o Secondary

- 150-

- 100-
0

50- o
o 2
@00�r2 = 0.93

A I , I I
0 50 100 150 200 250

ROD5 LOADING (kg/ha-d)

FIGURE 3

EFFECT OF BOD LOADING ON BOD REMOVAL
(from Ludwig et al., 1980)

Table 6
COSTS AND ENERGY UTILIZATION FOR ACTIVATED
SLUDGE AND ARTIFICIAL WETLAND TREATMENT SYSTEMSa

PLANT SIZE, mgd

0.1 0.5 1.0

ITEM CONV. AQUA CONV. AQUA CONV. AQUA

Capital cost, $x10-6 0.71 0.37 1.23 0.55 1.60 0.90
O & M cost, $/yr x10-3 35 21 78 48 117 74
Energy, Btu/yr x10-9 0.88 0.51 3.15 1.20 4.80 2.08

aAdapted from Tchobanoglous, et al., (1979).

costs. It is anticipated that consideration of employment opportunities will
become more important in the future.
Depending on the site, aquatic systems may have additional costs and/or
benefits. Additional costs may include the control of vectors, such as mosquitoes,
or other problems relating to the presence of marshlike environments, e.g. fog
generation. Beneficially, aquatic systems may serve as recreation areas or
greenbelts.

Federal Legislation and Administrative Policy

The passage of the Clean Water Act of 1977 (PL 95-217) encourages
the use of innovative and alternative technologies for water reuse. Conventional
treatment facilities will not be funded unless alternative treatment processes
have been studied and evaluated. Financial bonuses are offered when alternative
processes are designed; but many consulting engineers are reluctant to submit
treatment-plant designs based on technology that is not nearly as well documented
as the conventional treatment systems. Up to 75 percent of the construction
costs of new treatment systems is provided for in PL 92-500, but operational
funds are not provided. As a result, several advanced wastewater treatment
facilities have had to shut down because of excessive operating costs. In the
future, rising costs for energy and resources will probably cause the shutdown
of additional plants and change the design and operation of others. If they can
be shown to be feasible, aquatic systems may offer an alternative. Ultimately
it may be necessary to revise the existing discharge requirements to make the
use of aquatic systems a reality.

ACKNOWLEDGEMENTS

This work was supported with funds made available.7from the California
State Water Resources Control Board to the Department of Civil Engineering
and the Department of Land, Air, and Water Resources, University of California,
Davis, Calif ornia.

LITERATURE CITED

Colt, J1. et al. 1980a. The use and Potential of Aquatic Species for Wastewater
Treatment. Appendix D. The Environmental Requirements of Freshwater
Bivalves. Publication No. 65, Califorrqia State Water Resources Control Board,
Sacramento, Calif ornia.

Colt, J. et al. 1980b. The Use and Potential of Aquatic Species for Wastewater
Treatment. Appendix C. The Environmental Requirements of Crustaceans.
Publication No. 65, California State Water Resources Control Board, Sacramento,
Calif ornia.

Colt, J., S. Mitchell, G. Tchobanoglous, and A. Knight, 1979. The Use and
Potential of Aquatic Species for Wastewater Treatment. Appendix B. The
Environmental Requirements of Fish. Publication No. 65, California State Water
Resources Control Board, Sacramento, California.

Duffer, W. R. and J. E. Mayer. 1978. Municipal Wastewater Aquaculture. U.S.
Environmental Protection Agency, EPA-600/2-78-110, Ada, Oklahoma, 46 pp.

Golueke, C. G. 1979. Aquaculture in Resource Recovery. Compost Science/Land
Utilization, 20(3):16-23.

Kildow, 3. and 3. E. Huguenin, 1974. Problems and Potential of Recycling
Wastes for Aquaculture. Massachusetts Institute of Technology, Cambridge,
Massachussets, MITSG 74-27, 170 pp.

Ludwig, R. et al. 1980. The Use and Potential of Aquatic Species for Wastewater
Treatment. Appendix E. The Use of Aquatic Systems for Wastewater Treatment:
An Assessment. Publication No. 65, California State Water Resources Control
Board, Sacramento, California.

McKim, H. L. 1978. State of Knowledge in Land Treatment of Wastewater.
Volume 2, U.S. Army Corps of Engineers, Hanover, New Hampshire, 423 pp.

Metcalf and Eddy, Inc. 1979. Wastewater Engineering: Treatment, Disposal,
Reuse. McGraw-Hill, New York, 920 pp.

National Research Council. 1976. Making Aquatic Weeds Useful: Some
Perspectives for Developing Countries. Washington, D.C., 174 pp.

Sculthorpe, C. D. 1967. The Biology of Aquatic Vascular Plants. Edward Arnold
Ltd. London, 580 pp.

Standard Methods. 14th ed., 1976. American Public Health Association,
Washington, D.C., 1193 pp.

Stephenson, M., G. Turner, P. Pope, A. Knight, and G. Tchobanoglous. 1980.
The Use and Potential of Aquatic Species for Wastewater Treatment. Appendix
A. The Environmental Requirements of Aquatic Plants. Publication No. 65,
California State Water Resources Control Board, Sacramento, California.

Stowell, R., R. Ludwig, 3. Colt, G. Tchobanoglous. 1980. Toward the Rational
Design of Aquatic Treatment Systems. Presented at the American Society of
Civil Engineers Spring Convention, Portland, Oregon, April 14-18, 1980, 43 pp.

Tchobanoglous, G., 3. Colt, and R. Crites. 1979. Energy and Resource
Consumption in Land and Aquatic Treatment Systems. Presented at the Energy
Optimization of Water and Wastewater Management for Municipal and Industrial
Applications Conference, Department of Energy, New Orleans, Louisiana,
December 10-13, 1979, 12 pp.

Tourbier, 3. and R. W. Pierson, Jr. (Eds.). 1976. Biological Control of Water
Pollution, University of Pennsylvania Press, Philadelphia, 340 pp.

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Color infrared aerial photo of the Houghton Lake, Michigan wetland
wastewater treatment facility at the Porter Ranch peatlands. Areas of reddish
brown color near the irrigation pipeline depict areas of highest productivity.
Partially treated wastewater is pumped through a 12" diameter underground
force main to the edge of the wetland. At the lower left hand side of the
photo the transfer line surfaces and runs along a raised wooden platform for
a distance of about 2,500' to the discharge area in the center of the wetland.
Inserts depict the wastewater being distributed into the wetland through
3,200' of gated irrigation pipe.

WETLAND PROCESSES: SESSION SUMMARY

Presentations in this Session cover wastewater treatment utilizing
natural and artificial wetlands. Several regions of the United States
are represented with projects being located in California, Florida,
Massachusetts, Michigan, and Wisconsin.

Results of these studies indicate that discharge of secondary wastewater
into natural wetlands can be an effective treatment mechanism. One
full-scale municipal system has been established. The wetlands process
was the alternative selected for expansion of a sewage treatment plant
in northern Michigan. The concept and design were approved by regulatory
agencies, and the construction phase of the 201 Facilities Planning process
was completed during 1978. This natural wetlands system has been very
successful in the removal of nutrients from secondary sewage effluent.

Creation of an artificial marsh has demonstrated substantial environ-
mental benefits. A 21-acre marsh was created in the San Francisco Bay
area of California. The primary purpose of establishing the system was
to provide additional wildlife habitat. An average of 1,600,000 gallons
of secondary sewage is discharged daily into the artificial marsh. The
system has been very successful with 86 species of birds, 63 plant species,
34 species of aquatic invertebrates, and 22 species of other animals
having been identified. Improved water quality was an additional benefit
noted.

These exploratory or "proof of concept" studies constitute an extremely
valuable contribution to the technology base required for advanced or
developmental studies in the wetlands area of wastewater aquaculture.
At this time, the technology base appears adequate to warrant considera-
tion of design and evaluation of pilot-scale wetlands facilities for the
purposes of stripping nutrients from secondarily treated wastewater and
creating additional wildlife habitat.

Prepared by
William R. Duffer
1/3/80

WETLANDS CREATION FOR HABITAT AND TREATMENT - AT MT. VIEW SANITARY DISTRICT, CA.

Francesca C. Demgen , Aquatic Biologist, Mt. View Sanitary District,
Martinez, California

In 1974 the Mt. View Sanit~ary District (MVSD), near Martinez, California
initiated a full scale pilot wetlands creation program on low lying reclaimed
tide lands owned by the District. The objective of the program was to
demonstrate the feasibility of utilizing plant effluent to create a wetlands
environment for the benefit of wildlife and migratory waterfowl and to develop
management techniques for improvement of both water quality and wildlife
habitat.

The concept of using treated sewage effluent as a freshwater source for the
creation and restoration of wetland ecosystems qualifies as an alternative
wastewater management technology for meeting the objectives of the 1977 Clean
Water Act Amendments promoting the use of land treatment processes that reclaim
and reuse municipal wastewater. Wetlands reclamation projects are cost-
effective and depending on site conditions, energy requirements are minimal.
Wetlands projects also are consistent with EPA's multiple use policy supporting
wastewater management practices which combine open space, recreational and
educational considerations with such management.

PHYSICAL FACILITIES DESCRIPTION

Treatment Plant

Mt. View Sanitary District was established in 1923. It serves a portion of
the City of Martinez and unincorporated areas of Contra Costa County, with a
present population of approximately 14,000. The process provides two-stage
biofiltration with separate sludge digestion. Facilities include comminution,
primary and secondary clarifiers, a rock biofilter with a rotating dual
distributor, recirculation pumps and chlorination facilities. Sludge handling
facilities include grit removal, sludge thickening and primary and secondary
sludge digestion. A belt-filter press and paved drying beds provide for
sludge dewatering. The plant is designed to provide full secondary treatment
for 1.6 I4GD dry weather flow with a hydraulic capacity of 8.0 MCD wet
weather flow. Present dry weather flow is approximately .7 MOD. Effluent
consistently meets standard secondary treatment requirements of 30 mg/l
biochemical oxygen demand and suspended solids.

Wetlands

The wetland system covers 20.3 acres (8.2 ha) and consists of five inter-
p ~connected areas with tributary edge habitat. The total plant flow passes
through the ponds and marshes into Peyton Slough which discharges into
Suisun Bay. At present flow of .7 MCD there is a ten day detention time.
Land useage is 27acA4G. At the design capacity of the treatment plant,
1.6 MCD, there will be a 5 day detention time and 12ac/,NG. This ratio will
still provide for a beneficial habitat.

As shown in Figure 1, plant effluent is conveyed by gravity through an out-
fall pipe and siphon under Peyton Slough to plot D. This area is divided
with earthen dikes in serpentine fashion. This method of channelization
directs the flow through the emergent vegetation, to guarantee adequate
circulation. The final cell of plot D contains Ecofloats (EBC Company)
which are strung across the open water. These devices are made of redwood
bark, wood, and styrofoam for floatation. They serve as artificial substrate
or habitat for aquatic invertebrates which normally colonize the bottom muds
and emergent vegetation. Thus they increase the numbers of organisms which can
live in open water thereby enhancing the food chain.

The flow passes from the Ecofloat pond over weirs into plots C and E. Marsh
plot E is planted to provide food for migratory waterfowl using water grass
and alkali bulrush (Echinochloa crusgalli and Scirpus robustus). Since the
District wetlands are located on the Pacific Flyway the possibility exists
to feed many migratory waterfowl. Marsh plot C is open water with four
vegetated islands which provide food, cover and nesting sites removed from
predators.

The discharges from plots C and E are combined and flow by gravity through
the inverted siphon to the slough from which the flow is directed to both
plots A-1 and B. Flow through the wetlands system is entirely by gravity.
Dinges1 points out that high pressure pumps and excessive velocities should
be avoided since they harm aquatic invertebrates which are important for
maintaining a balanced ecosystem. The water level in each plot is controlled
by adjustable weirs and ranges from .3-1m.

Plots A-I, A-2, and B formed the original wetlands system whose objective
was to compare the creation of vegetated versus open water habitats. It
was determined that both types were successfully created and that the
combination provided a more stable, total habitat than either type alone.
Plot B is mixed open water and emergent vegetation. Plot A-1 contains
emergents and A-2 is an open water area with supplemental invertebrate
habitat. Large open water areas are particularly important in attracting
migratory ducks, the area must be visible to the waterfowl while flying.
The flow is discharged to Peyton Slough from plots A-2 and B.

WATER QUALITY CHARACTERISTICS

The wetlands environment has a positive effect on the treatment plant
effluent. Various monitoring programs have been carried out during the
life of the project to assess the water quality within the wetlands and also
the quality of water discharged from the system.2 The local climate is
mild, average daytime water temperature is 190C, range 5-290C. The pH
normally remains between 7.0 - 7.4 units; increases up to 8.8 units occur
accompanying algal blooms. The District treats only domestic wastewater
with very low metal content. Therefore, the wetlands is not monitored for
metals. Disinfection with chlorine to achieve a total coliform level of 23
MPN is accomplished prior to the wetlands. The initial portion of plot D
is used for dechlorination, the residual entering D is 1.0-4.0 mg/l. APHA
Standard Methods, 14th Edition procedures are referenced for each analysis.
The data discussed is on only plots A-1, A-2 and B, which have been in
operation since the fall of 1974. Plots C, D, and E were constructed in
the fall of 1978 and are now being monitored.

Dissolved Oxygen

The levels of dissolved oxygen (DO), measured with a portable meter (method
422F), vary diurnally and seasonally from about 1.Omg/l to supersaturation.
Normally levels above 5mg/l are maintained. Due to the shallow depths and
frequent wind mixing, the dissolved oxygen levels do not become stratified.
The highest levels of DO are caused by algae and occur in summer months.
The lower levels of DO occur in the early morning hours. In general, the
DO in winter months has a lower, smaller range. Even with the wide range of
DO levels there have been no odor problems or anaerobic conditions associated
with the wetlands.

Biochemical Oxygen Demand

Figure 2 shows biochemical oxygen demand (BOD, method 507) and suspended
solids data in six-month intervals divided into growing season and non-
growing season. The water quality in a biological system, such as the wet-
lands, is affected by the seasonal life processes occurring there. The
average BOD loading rate is 172 lbs/day and has been consistently reduced
by marsh B; only in two six-month periods did the BOD remain the same as
it was in the plant effluent, i.e., influent to the wetlands. The A complex
reduced the BOD in the winter months and the summer of 1977, but raised the
BOD during the other two summers. It must be stressed, however, that the
type of BOD leaving the treatment plant and that leaving the marsh system
differ. Materials comprising the BOD in the plant effluent are the degrada-
tion products of human waste. The material exerting a BOD in the marsh
effluent is partially composed of algae and other living organisms at the
very base of the food chain. These constituents are ready to be used by
organisms downstream whereas the materials in the plant effluent are not yet
in a usable form.

Suspended Solids

Suspended solids (SS, method 208 D) data for the four years to date show
that in the strict sense, SS are usually reduced in the winters but not in
the summer. The average loading rate to the wetlands is 189 lbs/day. When
SS leaving the wetlands are higher than the values found for the plant
effluent it can be attributed to algal growth in the pond-like portion of
system or silt from winter runoff. Therefore, it is especially important to
acknowledge the form in which the SS leave the wetlands because algae com-
prises the producer level of the food chain. This producer status means
that the algae is the base of the food pyramid allowing a healthy, balanced
ecosystem to occur in the marshes and slough.

When the results of plots A and B are compared it is apparent that if water
quality criteria are placed on a wetland discharge, the system should be
designed with a vegetated cell last in the flow scheme. Dinges3 work with
floating vegetation and Spangler et a14 working with emergents have both
concluded that aquatic vegetation is an effective means of improving various
water quality parameters.

Nutrients

Nutrient levels in the plant effluent are variously affected by the wet-
lands. In some cases nutrients are removed and in others, levels remain
unchanged. The nutrient analyses were run on grab samples collected during
1975-1978, using the following methods: nitrate 419D, ammonia 418B with
distillation, total organic nitrogen 421, total phosphate 425F. Table 1
gives the average, range and percentage of wetlands samples that had a lower
level of the nutrient than did the plant effluent sample on the same day.
Consistent nitrate removal is accomplished by the wetlands. Nitrification
does not occur to any great extent. Phosphorus does not appear to be a
limiting nutrient, the amount entering is also discharged. There is a
great deal of biological activity in the wetlands, a balance seems to be in
affect such that nutrients are neither added to nor extracted from the
system. The exception to this is the consistent reduction of nitrate levels.

THE HABITAT

Numerous ponds, marshes and rivers in the United States are fed, in part,
with treated wastewater. The unique aspects of this project are 1) a wet-
lands exists where previously there was none, 2) the sole source of water is
treated wastewater, 3) the primary purpose for creating the wetlands is to
provide wildlife habitat. The major goal of this research has been to de-
fine the components of this newly created wetland habitat. Only after
defining what exists can one then proceed to determine success or failure of
the project. The habitat types which comprise the wetlands are 1) open water
alone or in combination with ecofloats or islands, 2) areas covered by float-
ing vegetation - either free floating such as Lemna sp. or rooted on the
levees and floating 2-3 ft. out over the water, 3) areas of emergents, 4)
cultivated waterfowl food area and accompanying mud flats, 5) levees and
adjacent land with grasses, bushes and some trees.

Vegetation

A wetlands community is complex and is composed of both terrestrial and
aquatic forms of plants and animals. There are more than 72 species of
macrophytes in the MVSD wetlands, none were planted by the District. Twelve
of these are emergents: Typha spp., Scirpus spp., sedges; another 10 are
particularly saline tolerant, 29 are native to California. In the early
1800's the site was covered by a brackish water marsh, which was later
diked and drained. This accounts for the saline nature of the soil. The
remaining plants are field annuals, perennials, herbs and shrubs. The
vegetation serves as food, shields animals from predators, provides nesting
sites and improves some water quality parameters. Nineteen of the species
have seeds that are used by waterfowl for food.5 As winter progresses food
becomes more scarce and the birds and animals eat many plants or plant parts
not otherwise eaten. Planting the 2.5 acre plot E in seed producing vegeta-
tion will expand the available food supply.

An open water area mixed with stands of emergent vegetation provides the
habitat necessary for a greater variety of organisms. This diversity and
interdependence of plant and animal species leads to ecological stability.

The surface area of the wetlands is approximately 63% open water combined
with 37% covered by emergent vegetation. Voigts notes that this inter-
spersed type of habitat fosters a great variety of aquatic invertebrates and
also appears to attract the greatest variety of nesting birds.6 In a
biomass study done on this emergent vegetation it was found that Typha
latifolia can produce up to 18 lbs/sq m and Scirpus californicus up to
24 lbs/sq m, both as dry weight.

Algae. The algal growth in the wetlands is highly beneficial. It oxygenates
the water, removes ammonia, and serves as a food source for small herbivorous
animals such as the zooplankton. The wetlands system has never been plagued
by the growth of nuisance algae: no filamentous mats, no blue-greens, no
odor producers. The dominant algae present over a two year period were:
euglenoids, chlamydomonids, chlorella-like, and naviculates. Light and
dark bottle productivity analysis has been carried out over a two year
period. The low temperatures and overcast conditions of winter keep produc-
tivity very low to non-existent. During the summers studied, 1977 and 1978,
algal growth was cyclical. However, numbers of algal cells, therefore
oxygen evolution, was much greater in 1978. It is theorized that this
increased number of cells can be accounted for by the decrease in zooplankton
population and other algal predators. The decrease in the zooplankton was
due to the increased number of mosquito fish (Gambusia afinis). This
is a humanly created upset in the ecological balance of the wetlands. Marsh
management techniques provided the increase in mosquito fish, which success-
fully eliminated mosquito breeding. However, it also had this marked affect
on algal growth. During the fall of 1978 as many as 52 common and snowy
egrets were feeding on the mosquito fish, in a four acre area. Some of the
excess fish were trapped by other local agencies. It is hoped that in the
coming year a balance can again be reached between the numbers of fish and
invertebrates.

Animals

Twenty-two species of animals live at the MVSD wetlands: 10 species of
mammals, 4 sp. of amphibians, 4 sp. of reptiles, 3 sp. of fish. Rask studied
the south levee of plot B and found heavy use by mice (Mus musculus and
Reithrodontomys megalotis) and muskrats (Ondatra zibethica).7 The animal list
includes both herbivores and carnivores; many of the species reproduce and
live solely on what exists in the manmade wetlands. All of these animals
have come to the District on their own.

Birds. Ninety species of birds either live in or stop at the wetlands during
migration. This is a very large variety for such a small area, clearly wet-
lands are critical in the San Francisco Bay area. Schulenburg estimates that
70% of California's wetlands have been lost to draining and filling, since
the turn of the century.8

An approximate breakdown of species composition is 15 sp. of ducks, 32 sp.
of water and shorebirds, 30 passerine species, and 6 sp. of raptors.4
It appears that many of the migratory birds return each year. If it is not
the same individuals it is at least the same species returning at the same
time each year. In some cases these birds are somewhat uncommon in the
locality, which leads the author to believe it is the same flock returning,

for example tri-colored blackbirds. There are two types of usage of the
wetlands by migratory birds. Some flocks will stay only a few hours or less,
other flocks will spend weeks or months at the wetlands before moving to
their destination, usually Canada or Southern California. For example, a
flock of approximately 90 ruddy ducks spent two winter months whereas a pair
of mallards spent only one morning. Predatory birds, for instance herons
and hawks, need a large range and the MVSD wetlands is included in the
territory they rely on for food. There are a number of bird families in
which many generations have hatched, grown and reproduced entirely dependent
on the wetlands. A successful nesting this spring, 1979, of cinnamon teal will
be the fourth generation. The quality of the water and chemical content of
the vegetation must be acceptable since it enables the organisms feeding on it
to continually produce viable offspring. The available food supply appears
to define the carrying capacity of the wetlands, for birds. This is why
the cultivation of seed bearing plants was initiated.

Aquatic Invertebrates. There are more than 34 species of aquatic inverte-
brates living in the wetlands: 8 sp. of bugs and beetles, 10 sp. of flies,
7 other insects, 5 sp. of zooplankton, 4 sp. of non-insects.5 Voights study-
ing four marshes in Iowa found the number of taxa present to be between
20-32, with a maximum of 43.6 This is clear evidence that a species list of
34 is comparable to that found in other small wetland areas. It is probable
that there are more species than have been identified of zooplankton, due
to the difficulty of identification. Nearly all of these organisms exist in
the wetlands in each of their life stages. For these organisms to be able
to reproduce successfully generation after generation they have to be living
in high quality water. The volume of invertebrates and the species diversity
also are clear indicators that a stable ecosystem has been created. During
the summer of 1977 up to 3.8 lbs/hr. of zooplankton, mostly Daphnia, were
trapped in the outlet weir of plot A-2. This is a considerable volume of
food available for use by larger invertebrates and fish living within the
wetlands and downstream.

WETLANDS MANAGEMENT

A well designed project reduces the amount of necessary maintenance. The
major design objective is to create a balanced habitat and avoid nuisance
situations. Much was gained during the first four years of operation of
plots A-l, A-2, and B. This knowledge was incorporated in the design of the
three areas added in 1978.

Levees

All levees should be wide enough for vehicular traffic so they may be
utilized for maintenance when necessary. Some levees are used on a regular
basis, others are not and vegetation is allowed to cover them. These vegeta-
tion covered levees add to the habitat but provide access when needed.
Levees should be at least 10' wide, steep-sided, with 1.5' freeboard, and
compacted during construction. There are many wetlands organisms which
tunnel in levees: muskrats, gophers, crayfish, and other small mammals.
Therefore proper levee design and construction is crucial to keeping
maintenance needs minimal.

Eros ion

Vegetation is the main form of erosion control and works quite well once
established. A minimum of one spring and summer are needed before the
vegetation can become established, without specific planting and cultivation.
Vegetation is not sufficient around weirs, gates and pipes. These areas
must be fortified with riprap. The District is fortunate in this respect
because it is located en route to the local landfill and gets all its riprap
free of charge.

Plot Design

By dividing the total area designated for the wetlands into plots more
habitat goals may be achieved. When a multiple plot system is created flow
variation is facilitated. This allows one plot to be isolated from the system
in case of major maintenance needs. Multiple plots also allow depth variation.
Depth is a key factor in habitat design: it will determine whether or not
emergent vegetation will be present and will affect temperature and dissolved
oxygen values. Plot shapes may vary but small, constricted areas should be
avoided as they would promote stagnation and vector problems. Deciding
which groups of organisms are desired in the wetlands and knowing what condi-
tions these organisms normally live under will determine the fundamental com-
ponents of the design.

Vectors

Botulism. Clostridum botulinum is the cause of avian botulism and will not
cause botulism in humans. It is, however, deadly to waterfowl and certain
measures may be taken to avoid its occurrence. There have been no known
cases of avian botulism at the MVSD wetlands. Avoiding anaerobic conditions
by keeping the water circulating and maintaining the depth under 3' is an
important factor in botulism avoidance. Removal of floating organic debris
which collects behind weirs and in corners is regularly done. Steep-sided
levees, adjustable broad crested weirs for controlling water levels, conveying
water by pipeline, and ability to shunt a plot out of service for draining,
are also factors in the botulism avoidance program.

Mosquitoes. Mosquitoes lay eggs in water and the larva grow there under-
going metamorphosis to the adult form. To breathe the larva must hang from
the surface film of the water, piercing it with their respiratory tube
to obtain oxygen. This knowledge of the mosquito life cycle and habitat
needs helps the wetlands manager avoid mosquito breeding problems. open
water areas, subject to wind action and providing easy access for predators,
limit mosquito production. Maintaining good circulation in vegetated areas
provides for predator access and lessens mosquito production. These factors
have been the key to MVSD success in keeping mosquito production minimal in
1978. Figure 3 compares the numbers of adult female mosquitoes caught in a
light trap monitored by the Contra Costa County Mosquito Abatement District.9
The insects are collected and counted weekly, analysis began in August of
1976. The drastic reduction in numbers of mosquitoes trapped in late summer
of 1977 and all of 1978 was due to the transplanting of mosquito fish

(Gambusia afinis) in the early summer of 1977. Fish were taken out of Peyton
Slough and stocked in plots A-1, A-2, and B. By the end of the summer
their numbers had increased enough to have the mosquito larvae population
greatly reduced. Enough of the fish wintered over such that in the spring of
1978 they multiplied quickly and soon had the mosquito population under
control. The rise in numbers at the end of 1978 was due to water trapped
on property adjacent to the District's. Good circulation and adequate
numbers of predatory fish have allowed MVSD to operate a wetland project
which does not produce vector problems.

COSTS AND BENEFITS

The capital cost of the entire 20.3 acre wetlands was $94,000. Average annual
operation and maintenance expenditures over 4.5 years have been $1,200/yr.
Additional to this figure would be salaries for approximately 10 hrs/wk of
system maintenance and 15 hrs/wk for monitoring and management. No pumping
costs are associated with the gravity flow wetlands system. The amount of
time necessary by personnel depends on the amount of monitoring required
and on maintenance needs which vary seasonally and can be greatly reduced by
careful design of both the hydraulics and physical features of the system.

Benefits of the wetlands system using treated wastewater include improved
water quality, habitat creation, and recreational and educational opportunities.
The wetlands is MVSD's contribution to the community, and it receives heavy
use. The recreational and educational benefits included in the wetlands
are a good example of the intent of section 201(g) (6) of the Clean Water
Act of 1977 "The Administrator shall not make grants... (for) treatment
works unless the grant applicant has satisfactorily demonstrated to the
Administrator that the applicant has analyzed the potential recreation and
open space opportunities in the planning of the proposed treatment works."
There are visitors of all types ranging from neighborhood children who look
for animal tracks to organized group tours for college students and environ-
mental groups. The District has hosted researchers, municipal officials,
and nature photographers. The local Audubon Society gave the District an
award for its work and has declared the wetlands to be one of the best birding
areas in the county. The California Chapter of the Soil Conservation Society
of America has also officially commended the District for its work on water
reuse and habitat creation. There is broad recreational potential in this
type of water reuse project. Table 2 delineates the hourly usage of the
wetlands by the public.

A wetlands system also has income possibilities. For example, during the
summer of 1978 there was an over abundance of mosquito fish in the ponds.
The local mosquito abatement district seined fish out of the ponds for their use.
A local wildlife rehabilitation center and museum collects fish as well as
duckweed and invertebrates for animal food. The District could charge for
the fish and other food products produced.10 The possibility exists to sell
crayfish for bait or aquatic invertebrates for tropical fish food.11 An
option for a large wetlands would be to rent a portion of it to a duck club
for hunting.

CONCLUS IONS

The protection, restoration and enhancement of wetlands has become a national
g~oal. The potential environmental benefits derived from utilizing treated
municipal wastewater for wetland restoration and enhancement has been

demonstrated by the Mt. View Sanitary District's wetlands project. The
project also demonstrates a reuse method that combines wastewater and wild-
life management for optimum results. Wetlands systems created and main-
tained with treated wastewater are cost-effective and low in energy require-
ments. (1) A balanced anid healthy wetlands ecosystem, composed of pond and
marsh areas, has been successfully created using secondary treated wastewater.
(2) The wildlife habitat actively supports 72 sp. of plants, 21 sp. of animals,
90 sp. of birds and 34 sp. of aquatic invertebrates. (3) Mosquito breeding
has been reduced to a minimum through the use of natural predators. Avian
botulism and odors have been avoided. (4) Redwood bark floats provide
supplementary habitat for aquatic invertebrates, thereby increasing their
populations in open water. (5) Nitrate removal is consistent. BOD and SS
removal is seasonal - if algae was not regarded as a component of SS they
would then be consistently lowered. (6) Public support for the wetlands is
strong, educational and recreational usage is considerable and increasing.

PART 2 MARSH-FOREST PILOT PROJECT

In December 1978 EBC Company initiated a pilot project at Mt. View Sanitary
District. The objectives of this marsh-forest project are to 1) combine
wetland and upland habitats, 2) to improve the water quality of the secondary
effluent coming from the treatment plant, 3) to produce a cash crop of waste-
water irrigated redwood trees. Figure 4 shows the marsh-forest layout.
The pond is 20' x 40' x 3' and the forest is 40' x 100'. The pond receives
3600gpd of secondary effluent, the water is then pumped to the underground
irrigation system which consists of 1�2" PVC pipe connecting K-6 infiltration
units under each tree. Water passing through the irrigation system is col-
lected in a splitter box from which some is discharged and some is recirculated.
Water quality analyses are performed on the water in this final splitter box:
averages of weekly analyses for 8.5 months show BOD and SS levels at 8.1 mT /1
and 6.2 mg/l respectively. The redwood trees have grown 1.5' in 7 months. 12
The project appears to be meeting its goals of producing a high quality
effluent and the irrigation system is functioning well. The trees are grow-
ing rapidly. Eight varieties of aquatic invertebrates have been identified
from the duckweed covered pond. The system will continue to be monitored
on a weekly basis for BOD and SS, monthly for nutrients, color, turbidity,
and TDS.

TABLE I. WETLANDS INFLUENT AND EFFLUENT NUTRIENT LEVEL AVERAGES, 1975-1978.

Average (mg/1) Range (mg/1) % Reductionsa
Nutrient Influentb Ac Bd Effluent A and B A B

NO3-N 7.4 3.3 1.7 .55-18 .06-16 90 97
NH3-N 7.9 6.7 6.8 .24-15 .1 -19 60 56
Org-N 4.8 4.4 4.6 .4-14 .09-17 56 63
PO4 9.9 9.1 10 .44-18 .48-18 53 37

a) This is the percentage of samples when the marsh discharge was lower
than the marsh influent, i.e., plant effluent.

b) Wetlands influent is secondary treatment plant effluent.

c) Effluent of plot A.

d) Effluent of plot B.

TABLE II. PUBLIC USAGE OF WETLANDS (HOURS).

Year Education Recreation Total Hours/acre*

1977 292 280 572 52
1978 524 291 815 74

*Unexpanded system of 11 acres.

PLRSH NHPOT RO

FgLOTe 1 Wtlads P

eo ~~~~PLOT A-I -

srTe PLAN
MT. VIEW SANITARY DISTRICT
MARSH ENtANCEMENT PROGRAM

Figure 1 Wetlands Plot Plan

80-BOD I 1-SUSPENDED
(6 mo. avg.) SOLIDS

i/
~0 30~ mo~ avg/ \}|~' IMa'

/\ cs40

20 _ 20 . t
30 � r 30 :

- . SEC EFFLUENT ENTERING MARSH
EFFLUENT FROM MARSH A
EFFLUENT FROM MARSH B

FIG. 2 Biochemical Oxygen Demand and Suspended Solids Data

540

13 0
LIJ

cc
uj ~ ~ I

197

-Ad

I~ ~ ~ ~ ~ ~~~~~~~ETO 31

MAY JU~~~~~~~~~~~1E JU~~~~~~LY AG. SE T.ECFO-

1976 FIGUR~~~~~~~~E 3 OPN
_________ ~ ~ ~ ~ ~ ~ ~ TF 1977R-I --
1978~ ~CTC BASQUT R CION

FICUE 4Kmrh-F~ret Ly~u r2ii-

SECTION7

REFERENCES

1. DINGES, RAY. "Wee Beasties May Improve Your Effluent."
Water and Wastes Engineering. 12(3):35-37. (March 1975).

2. DEMGEN, FRANCESCA C. and J. WARREN NUTE, INC. Marsh Enhancement Program
Conceptual Plan. Mt. View Sanitary District of Contra Costa County,
California. (November 1977).

3. DINGES, RAY. "Aquatic Vegetation and Water Pollution Control. Public
Health Implications." American Journal of Public Health, 68:1202-1205 (1978).

4. SPANGLER, FREDERIC R., WILLIAM E. SLOEY, C.W. FETTLER, JR. "Wastewater
Treatment by Natural and Artificial Marshes" September 1976.
U.S. EPA, Ada, Oklahoma 74820.

5. DEMGEN, FRANCESCA C. Biological Monograph: Containing supplementary
biological data of the Mt. View Sanitary District wetlands system as
related to literature search findings. Mt. View Sanitary District.
October 1978.

6. VOIGTS, D.K. "Aquatic Invertebrate Abundance in Relation to Changing
Marsh Vegetation." American Midland Naturalist. 95(2)313-322. (April 1976).

7. RASK, LAURIE MACDONALD Mammalian Inhabitants and Microhabitat Use
at a Freshwater Marsh Maintained with Wastewater Treatment Plant Effluent.
June 1, 1978.

8. SCHULENBURG, BOB. Preserving California's Wetlands. Outdoor California.
Sept.-Oct. 1976 p.6.

9. Mosquito light trap data courtesy of Chuck Beasley, PhD entomologist
for the Contra Costa County Mosquito Abatement District.

10. COLEMEN, MARK S. et al. Aquaculture as a Means to Achieve Effluent
Standards. Oklahoma State Dept. of Health. Excerpted from project
reports and reprinted for: Hinde Engineering Co., P.O. Box 188, High-
lands Park, IL 60035.

11. Local tropical fish stores have shown an interest in buying packaged,
sterile Daphnia for 40�/2 ounces. Peak Daphnia production yields 3.8
lbs/hr.

12. J. Warren Nute, Inc. Marsh-Forest Demonstration Project Feasibility
Assessment. 1979.

CYPRESS WETLANDS FOR TERTIARY TREATMENT

by
Walter R. Fritz, PE, Principal Engineer
and
Steven C. Helle, PE, Associate Civil Engineer
BOYLE ENGINEERING CORP.
3025 East South Street
Orlando, FL. 32803

In 1973, a team of environmental scientists, existing research into an applied engineering
under the direction of Dr. Howard T. Odum science suitable for implementation. Boyle
and Dr. Katherine Ewel at the University of engineers developed a three-phase approach
Florida's Center for Wetlands, developed to this project:
the concept of using cypress wetlands as a Phase I-Develop conceptual techniques
natural tertiary treatment mechanism for for using cypress wetlands for
domestic wastewaters. Working under grants tertiary treatment.
from the National Science Foundation and
the Rockefeller Foundation, they initiated a Phase 2-Determine the feasibility of
field investigation of the method. This dem- utilizing the method.
onstration project included an intensive Pae3Dvlppoeue n rlm
examination of two cypress domes which P ae3Dvlppoeue n rlm
were supplied with effluent from a small, inary regulations for implemen-
extended aeration, secondary treatment tation.
plant at Whitney Mobile Home Park near This article will address Phases I and 2.
Gainesville, Florida. The findings from these
domes were compared to the findings from Types of Cypress Wetlands
a third dome which was supplied with pure Thraetrebsitysofcpssw-
groundwater and a fourth dome which wasThraetrebsitysofcpssw-
left in its natural state as "control". Results lands: domes, strands and fringe.
of the research show that the two "sewage A cypress dome is a roughly circular-shaped
domes" effectively treated the effluent to cypress swamp, one to twenty-five acres in
well within acceptable tertiary treatment size, occupying a shallow, saucer-shaped
standards with no significant adverse effect depression which receives, water from sur-
on the environment. rounding higher grounds. The trees are
By 1976, the sponsors at the National Science tallest in the center of the area, giving the
Foundation were so encouraged with theseimrsonfannvtebwlrdm.
results that they provided Boyle Engineering The ecosystem supports lush vegetation
Corporation with a grant to convert the including cypress trees.

A cypress strand is a diffuse freshwater cypress strand and allowed to sheet-flow
stream flowing through a shallow forested through the strand (see Figure 3). The
depression on a gently sloping plain. Be- treatment mechanism relies on biological
cause of the water's relatively low erosive uptake by vegetation and the absorptive
powers, vegetation can grow in the river action of the underlying organic layer during
bed, further slowing water flow and spread- overland flow. Discharge is into downstream
ing it over a wide area. Marshes may cover waterways rather than percolation to ground-
shallower parts of the depression with waters as in the previous two concepts.
cypress forest in the deeper channels.
Feasibility Criteria
Lake fringe or riverine cypress are located
at the edge of lakes or rivers. These types Cypress wetland treatment of wastewater
of cypress wetlands are not suitable as will be feasible only if it compares favor-
treatment facilities since they offer no re- ably over a broad spectrum of variables
tention time before entering open water- with other tertiary treatment alternatives.
ways. The following series of questions (or criteria)
must be answered in order to avaluate the
Concepts of Using Cypress Wetlands attractiveness of the cypress wetland treat-
for Tertiary Treatment ment alternative.
"Natural Dome" Concept This concept *'Will the use of the method attain re-
requires little or no modification to the quired treatment results?
cypress dome or surrounding area (see Are the costs competitive with other
Figure 1). Treated wastewater is applied to available treatment methods?
the center of each dome and allowed to Are the costs and availability of required
pond or percolate through the underlying energy sources reasonable?
'What are the environmental effects on
soils to the groundwaters. Biological uptake
the dome and surrounding ecology?
from the vegetation, combined with filtering the me and surrounding ecology?
action from the organic layer, removes
essentially all nutrients, heavy metals, and * Is the method available to a significant
essentially all nutrients, heavy metals, and
coliform bacteria from the effluent. Al- number of users?
though not yet conclusive, virus contamin- Under what conditions (rules) will regula-
though not yet conclusive, virus contamin-
ation appears to be effectively absorbed by tory agencies allow the use of the
the shallow sandy layer immediately under- method?
neath the mucky organic floor of the dome. Treatment Results
"Isolated Dome" Concept In their natural
The main purpose of tertiary treatment is
state, cypress domes collect storm run-
fstate, c ypress domes collect storm run- the removal of nutrients, primarily nitrogen
off from surrounding lands, occasionally
off. from surrundiglndsoand phosphorus. Normally, tertiary treatment
filling to capacity and spilling over onto
will also remove additional amounts of BOD5,
surrounding areas. If wastewater is applied suspended solids, heavy metals, viruses, and
to the dome, problems may arise from over- coliform bacteria which are left from the
flow in certain situations. The Isolated secondary treatment process. Research from
Dome treatment concept virtually eliminates the Center for Wetlands' demonstration pro-
the possibility of spillover, making it a zero ject clearly shows excellent treatment re-
discharge system. Isolation is accomplished
suits. The research determined that 98 per-
by constructing an earth dike around the cent of the total nitrogen and 97 percent of
perimeter, thus preventing surface waters the total phosphorus was removed before
from filling the dome and dome waters from the treated wastewaters entered the under-
lying groundwater. The concentrations of
Flow Through Systems In a third treat- nutrients and all other monitored parameters
ment concept, the secondary effluent is in the groundwaters under and surrounding
distributed along the upstream side of a the sewage domes remained essentially the

CYPRESS WETLAND TREATMENT CONCEPTS

Figure 1

AUTOMATIC VALVE Natural
AND TIMER Natural
OCCASIONALr OCCASSIONAL SPILLOVER Dome
RUNOFF SPILLOVER Dome
- SECONDARY
'EFFLUENT
FORCE MAIN Concept
R ORGANICLAYER
CLAYEY
SANDS

Figure 2

NO AUTOMATIC VALVE Isolated
RUNOFF SPILLOVER Dome

~~DIKE ~~AA _DRFFLEN Concept
ORGANIC FORCE
~ / +/ _ r - LAYER MAIN
SANDS

CYPRESS STRAND

Figure 3

~3 zr~c , $ > Z m Flow
Through
MANAL System
O~U:~.L -____ . "/"E Concept
OVERLAND SHEET FLOW] ORGANIC LAYER ' FORCE MAIN SECONDARY
EFFLUENT
LITTLE OR NO PERCOLATION

same as background and measured levels in cost 42.2� per 1000 gallons compared to
the control domes. Thus, the groundwater 63.0� for spray irrigation and $1.07 for a
quality remained well within Federal Drink- physicallchemical treatment facility.
ing Water Standards.
Cypress strands seem to offer an economic
Similar results were achieved in a mixed hard- advantage over cypress domes because they
wood (with some cypress) "flow through" are more often available in larger contiguous
system near Wildwood, Florida. In this sys- areas. In many cases, the entire wastewater
tem, which is receiving effluent from a muni- flow could be served by a single cypress
cipal secondary treatment plant, nutrient strand, as opposed to multiple cypress
concentrations in the lower part of the domes. This minimizes the total length of
swamp were similar to or less than con- required force main and wetland perimeter
centrations in control areas and in Lake which often must be diked or fenced. In
Panasofkee, into which the swamp drains. another site specific cost analysis, the costs
This combined secondary treatment plant- of both of these cypress wetland methods
wetland system achieved results well within were compared for a treatment facility near
Florida Advanced Waste Treatment Standards. Orlando, Florida. The results of this analysis
revealed that it would cost 22.3� per 1000
Cost-Effectiveness gallons to use a large wetland strand corn-
Cypress wetlands must be economically pared to 71.2� per 1000 gallons to use the
attractive, compared to other tertiary treat- 44 nearest cypress domes which would be
ment methods, in order to be considered a required to treat the 1.2 mgd flow.
viable alternative. The cost-effectiveness of
cypress wetland treatment is highly site
specific, with the cost of land, length of Potential cypress wetland users are vitally
required force mains, average daily waste- interested in purchased energy requirements
water flow, the type of cypress wetland and because of their affect on revenues, tax
surroundings all being important variables. structures and budgets. In addition, recent
General cost analyses performed by Boyle Environmental Protection Agency grant pro-
engineers demonstrate cypress wetlands to grams have required consideration of pur-
to be cost-effective with certain combin- chased energy requirements during the
ations of these variables (see Figures 4-7). wastewater treatment facility planning pro-
Another cost analysis for an anticipated
treatment system in Waldo, Florida indicates Solar energy, through the processes of photo-
tertiary treatment by cypress wetlands to synthesis and evapotranspiration, is the

Figure 4 Figure 5
COST CURVES - 200000 GPD COST CURVES- 500,000 GPO

3.ooRC~ Xy//

r~~~ /,
I~~~~~~~~~~~~~~~Sw

t - n t L '... . ..
Isys .... s .....

LENGTH OF FORCE MAIN, MILES LENGTH OF FORCE MAIN. MILES

dominant energy form for cypress wetland natural recharge mechanisms, seriously en-
treatment. Wetland vegetation uses the dangering groundwater levels and supplies.
energy from the sun and the nutrients from Cypress domes serve as a reservoir system
the wastewater to grow and thrive, requiring by releasing stored surface waters slowly
neither purchased fossil fuel energy nor syn- through the organic layer into the under-
thetic chemicals. However, if wetlands are lying sands during times when groundwater
used as part of the treatment process, some is in short supply. The application of waste-
purchased energy must be used to pump water assures a nearly constant surface
the treated wastewater to the wetlands, and water supply which has a mollifying effect
chlorine may be required for disinfection on groundwater levels, balancing them be-
prior to application. tween wet and dry seasons. Further benefit
is derived by reduced fire danger to the dome
An analysis of the cypress wetland, physical/ an d surroundi ngetati on.
chemical, and upland spray irrigation alter-
natives was conducted to quantify and com- In certain situations, occasional overflows
pare purchased energy requirements. The of the treatment dome waters may be a pro-
results of this analysis indicate that wet- blem. Where unfavorable conditions exist,
land application is generally more energy- the problem can be solved by the imple-
efficient than either physicallchemical treat- mentation of the "Isolated Dome" treatment
ment or spray irrigation because it involves concept.
no power for aeration beyond secondary
no pwer or aratin beond econaryCypress domes and underlying sandy clay
treatment, nor does it require any residual Cyrsdoeanudrligadycy
treatment, nor doespit require any residual soil layers have been very effective in pre-
venting coliform and virus contamination of
groundwaters directly under the domes, un-
less the upper soil levels within the wetland
Cypress wetlands are tender wetland eco- are significantly disturbed. In one case, at
systems which have often been neglected the Center for Wetlands project, a mild in-
or abused. It is of utmost importance to trusion of fecal coliforms, 8 to 100 per 100
consider the impact on all aspects of the ml, was detected as a result of overflow onto
environment within and surrounding each highly porous soils. Bacterial and viral con-
wetland prior to the application of waste- tamination of groundwaters appears not to
waters. be a problem if the wastewater which is
Many of man's surface drainage control de- applied to the dome is sufficiently chlor-
Ma~~~~~~~~~~~~ny ated and all possible "short-circuits" to
vices, such as canals, drainage ditches and i nated and avoided.
the straightening of rivers, interfere with

Figure 6 Figure 7
COST CURVES - 1.0 MGD COST CURVES -2.0 MGD

4". go
,~~~~~//

W~~~~~-'"- '-' " --' ,'"V ^~oFs._.. ~~

!.,ev~~~~~~~~~A ~ Aa--_ zza L E G E N D ~ ~ to

LENGTH OF FORCE MAIN, MILES L ENGTH T OF FORCE MAIN, MILES

7 9

Cypress trees and other wetland vegetation The system must not be vulnerable to na-
appeared to suffer no detrimental effects tural disasters. One natural disaster which
from the introduction of wastewater. Indeed, could impair operation is a period of heavy
there is mounting evidence that the trees rains, causing a temporary spillover from
thrive in effluent. Analysis of the trees in a the dome. Runoff waters during these per-
strand near Waldo, Florida shows that they iods would serve as a dilution agent for the
grew 2.6 times faster after the wastewater overflowing wastewaters, reducing the dan-
was applied. ger of contamination. The only other likely
natural disaster affecting operation is forest
Introduction of sewage effluent to cypress
fire. Studies after fires in cypress domes
domes initiates an immediate appearance of demonstrate cypress trees have a remarkably
demonstrate cypress trees have a remarkably
duckweed, which readily covers the entire
water surface and serves a vital role in the high survival rate. In addition, the constant
water surface and serves a vital role in the
presence of water in the domes substantially
treatment process. The duckweed offsets a reduces the risk of fire.
reduced treatment capacity of the dormant
cypress trees during the winter months. Adequate supplies of required resources
Throughout the year, the duckweed utilizes must be available. The only resources re-
nearly one-half of the applied nitrogen, two- quired for cypress wetland treatment are:
thirds of the applied phosphorus, and nearly 1) wetlands, 2) sunshine, and 3) power for
all of the heavy metals. These materials then the pumps. The first two occur naturally and
become part of the organic layer in the wet- the power requirements are much less than
land floor through decomposition, making other tertiary treatment methods. There are
them available to the cypress tree root no chemicals, other than chlorine, required
systems. for cypress wetland treatment.
The operation must include a sufficient
Reliability factor of safety. Hydrogeologic and other
Wastewater production is an every day prerequisite studies are required to deter-
occurrence, 365 days a year, requiring waste- mine the quantifying parameters for design.
water treatment systems to be highly reliable. To prevent serious problems from unforeseen
The following criteria for evaluating the re- circumstances, factors of safety may be em-
liability of a land application tertiary treat- ployed by the designers when calculating
ment system has been established by the required wetland areas. Furthermore, holding
U.S. Environmental Protection Agency. These ponds can be installed to allow relatively
criteria apply equally well to wetland ap- even application of effluent and to prevent
plication systems. shock effect from peak loading.
The system must have the ability to meet or Availability
exceed treatment requirements. Center for
Wetlands' results have shown a reduction in In order for cypress wetland tertiary treat-
total nitrogen of 98 percent and total phos- ment to be feasible, adequate cypress wet-
phorus of 97 percent for the combined se- lands must be available to the secondary
condary treatment facility/cypress dome treatment facilities. To evaluate availability,
system. Essentially, groundwater nutrient a survey of approximately 40 percent of the
levels under sewage domes are the same as existing wastewater treatment facilities in
under control domes. Florida was conducted to compare treat-
ment facility sites with the location of cy-
Failure rates must be low. Cypress wetland
treatment requires little mechanical or elec- press and other forested wetlands. The
tronic equipment, minimizing the chances results of this survey can be extrapolated to
of failure. The wetlands are always available estimate availability for the entire state.
for full-time operation. Based on earlier portions of this investi-

gation, each facility was considered to have Conclusions
adequate cypress wetlands available to war-
rant further investigation into the feasibility The enter for Wetlands' research clearly
of implementation, if 300 acres per mgd
of implementation, if 300 acres per mgd nically feasible as an alternate method for
(design flow) were located within a reason- tertiary treatment. Cypress domes are, how
able distance. The following distances were tertiary treatment. Cypress domes are, how
able distance. Th oloin itacseeever, restricted in their applicability because
considered as reasonable: of low allowable loading rates and the rela-
1 mile for design flows less than 0.1 mgd, tively small areal extent of each dome. This
necessitates extensive force main networks
3 miles for design flows between 0.1 and
and creates large total perimeters to be diked
1.0 mgd, and
or fenced for all but the smallest treatment
5 miles for design flows over 1.0 mgd. facilities. Cypress strands, on the other hand,
are often fairly extensive areas which will
The following results were found from the
probably allow larger wastewater flows to
survey:
be treated at a single site. A detailed scien-
� 253 out of 2327 surveyed facilities have tific study of loading rates and treatment
adequate cypress domes. These 253 mechanisms in a cypress strand is currently
facilities represent about 3 percent of underway at Jasper, Florida under the direc
the total design flow. tion of Boyle Engineering Corporation.
* 583 out of 1679 surveyed facilities have
adequate forested wetlands (cypress
domes and strands, hydric hammocks).
These 583 facilities represent about 28
percent of the total design flow.
These results indicate that adequate forested
wetlands are available for 35 percent of the
wastewater treatment facilities in Florida
with a combined design flow of over 350 mgd.
If the method is restricted to cypress domes,
about 450 facilities, representing 43 mgd
design flow, can consider the wetland tertiary
treatment alternative.

Regulation
State and Federal regulatory agencies indi-
cate that they believe cypress wetland ter-
tiary treatment shows promise of being a
viable tertiary treatment alternative. This is
evidenced by their support and interest in
the Center for Wetlands' and related pro-
jects. However, the general regulatory con-
jcensus His that it is premature to create This material is based upon research supported by the
census rules that ismpremetatuton. caTey National Science Foundation under Grant No. ENV76-
explicit rules for implementation. They do 23276.
support, however, implementation of the
method on a case-by-case basis after demon- Any opinions, findings, and conclusions or recom-
mendations expressed in this publication are those of
stration of treatment results, environmental the author and do not necessarily reflect the views
concerns and cost-effectiveness. of the National Science Foundation.

THE DRUMMOND PROJECT - APPLYING LAGOON SEWAGE
EFFLUENT TO A BOG: AN OPERATIONAL TRIAL

William M. Kappel, U.S. Geological Survey, 521 W. Seneca Street,
Ithaca, New York 14850

INTRODUCTION

The Town of Drummnond is located in northwestern Wisconsin
approximately 70 miles southeast of Duluth, Minnesota, and within the
boundary of the Chequamegon National Forest. The town has a residential
population of approximately 280, a regional high school population of
400, and one sawmill as its only industry.

In 1971, Drummond was ordered by the Wisconsin in Department of
Natural Resources (WDNR), to develop a sewage treatment system for the
town. Existing sewage treatment consisted of individual septic systems
which did not function correctly due to heavy clay soils. This
condition necessitated the pumping of septic tanks at least twice a
year to prevent the discharge of primary effluent to stormwater
drainage ditches and Lake Drummond.

A three-cell, contact stabilization system was developed for
secondary treatment of the sewage. Twice a year treated secondary
effluent was to be discharged to the Long Lake Branch of the White
River, a class 1-A trout stream. The U.S. Forest Service became
involved with the project because the proposed system was to be built
on Forest Service land. Review of the Environmental Impact Statement
for the proposed project was not satisfactory to Forest Service
personnel, and after several l~ieetings with town officials, the WDNR,
and agencies funding the project, it was decided that construction
would commence on the lagoon system, but a different alternative for
final effluent discharge would be found.

Alternative Analysis

The Forest Service explored several different alternatives trying
to find a tertiary treatment system which would effectively treat the
effluent, protect the local and downstream environment and not add to
the construction costs of an already financially over-burdened town.

The use of a "natural" treatment system was considered as the best
method to meet the above objectives. Most of the sails around Drummond
are an organic wetland type, therefore, these materials seemed to offer
the best hope for treatment.

After an intensive literature review, several natural and artificial
wetland treatment systems were found. The artificial wetland (Meadow-
Marsh-Pond) system developed by Dr. Maxwell Small was considered, but
the costs of construction were too high. The Cypress Dome studies in
Florida, by Dr. Howard Odum, were also explored but here the costs of
pumping and maintenance of the piping system were considered too high.
The Forest Service had developed a tertiary peat-bed filter system using
a layered, grass over peat over a rapid sand filter, but again costs of
construction and maintenance were considered too high for the town to
carry.

A fourth alternative which held some promise was the variable ditch
systems of Finland. These systems use a shallow feeder ditch to apply
primary effluent to a peat bog. A deeper ditch approximately 20 to 40
meters distant draws the effluent from the shallow ditch through the
peat and into the deeper drainage ditch. Thirty years of use in Finland,
with good treatement results, made this system look viable, until the
costs of construction were calculated.

At this time a similar ditching system was being operated at
Bellaire, Michigan. This system functioned for a time until a heavy
rainstorm washed the ditch-system out. Dr. Robert Kadlec of the
University of Michigan, had studied the Bellaire system and was working
on a new system which was to be tried at Houghton Lake, Michigan. This
system was to disperse secondary effluent to a wetland using a pipeline
system. Speaking further with the consulting engineering firm, Williams
and Works, it was determined that this system might be feasible at
Drumnmond.

Investigation at the 10 ha bog southeast of the lagoon construction
site at Drummond revealed that a gated irrigation pipe system could be
used to apply the sewage effluent to the surface of this bog-wetland.

Description of the Drummond Bog

The Drummond area lies within the end moraine of the Cary-Valders
Advances of the Wisconsin Age Glacier; approximately 10 to 12,000 years
B.P. The area has a rolling topography with variable soil and vegeta-
tive cover. The treatment bog lies within a kettle-hole depression of
approximately 25 ha in size. The bog is perched above the local and
regional groundwater system due to a natural clay "liner". The watershed
surrounding the bog is 15 ha, with a vegetative cover type of northern
hardwoods, oak and maple.

The bog is comprised of decayed organic matter, as deep as 11
meters, with a cover mat of spaghnum moss species. Vegetative
cover species consist of Black Spruce, Tamarack (Larch), Leather
Leaf, Cranbury, and Blueberry.

The bog is located in the upper reach of an un-named feeder to
the Long Lake Branch. In this position, outflow from the bog only
occurs during the spring snowmelt-runoff period and occasionally
during heavy summer thunderstorms. During other periods no outflow
occurs. Water which does leave the bog flows down to the Weso
Lake, a small 2 ha lake which is surrounded by a sedge, cat-tail,
spaghnum wetland. A wet weather outflow from Weso Lake moves into
another extensive wetland before entering the Long Lake branch in a
diffuse flow pattern.

Operation of the Bog Irrigation System

Based upon the hydrology of the bog and the biology of the
eco-system, discharges to the wetland only occur between mid-april
and early November, when the bog surface is not frozen. During the
unfrozen period, the upper surface of the decaying peat, approximately
20 cm, and the growing cover species act as a physical, chemical, and
biological filter for the effluent. Physically, suspended solids are
filtered out, chemically, the high cation exchange rate of the peat
"holds" many of the inorganic nutrients, and biologically, micro-organisms,
as well as the vegetative species, take up some of the nutrients of the
effluent water as it passes through this living filter. Since this type
of wetland is generally nutrient-poor, the addition of nutrient-laden
water should act to stimulate vegetative growth within the wetland.
This will be discussed in the next section.

The hydrology of the bog will also be altered by the application
of the effluent. The effluent discharges are made from the secondary
pond onto the bog surface through the use of 215 meters of gated
irrigation pipe. The gates on the pipe are adjusted so even
dispersal of the effluent, across the bog surface, is accomplished.
The designed daily discharge is 100,000 gallons. The application
takes place over a three to four hour period, early in the morning,
to take advantage of peak evapo-transpiration rates during mid-day.
on the day of a discharge, local and regional weather forecasts are
followed to ascertain if any heavy rainfall (>2.5 cm) will occur in
the next 24 hours. If the weather looks good, the outflow weir is
checked to note the present discharge. Based upon the pretreatment
water budget, if the outflow discharge is less than .06 cfs a
discharge can be made every day. If the outflow rate is higher,
.06 to .12 cfs, discharge can be every other day, or if the discharge
is above .12 cfsl no discharge is made. The discussion of how
these rates were determined if found in the next section.

DRUMMO D~
TERIAR SE.WAG TREATMEN

-DEMOSRTION POECT

Original Proposed I .- -
Outfpfl lL-~ .-

\ ~~Constructed Outfall
nu0,? ' ~Outflow ~

DRUmmONO--- P ipe

L LI~~~~~~J

Research Projects

The research effort, at the treatment bog, encompasses four
major areas; a water-quality study, a vegetative study, a small
animal study, and a water and nutrient budget study. The following
section summarizes each study and the status of the work to date.
Most sutdies, except the small animal study, have at least one year
of pretreatment data. Discharges to the bog began in May 1979, and
most of this year's data has yet to be analyzed against pretreatment
data, but in recent discussions with most researchers, nothing
unexpected has occurred, yet.

An annual research meeting is held each spring at UW-Stevens
Point where the past year's data is summarized and the next year?'s
plans are discussed. These meetings are open to anyone interested in
the project. An active mailing list is maintained by the Forest
Service; biannual updates on the project are prepared and an active
interchange of ideas is always encouraged.

Water Quality

Dr. Bryon Shaw, Dave Mechenich
University of Wisconsin-Stevens Point
Stevens Point, Wisconsin 54481

Funding - Upper Great Lakes Regional Commission

This study consists of sampling water quality from the lagoon
system, through the treatment bog and downstream into the Weso Lake
system. In the bog, 15 clusters of wells, consisting of a combination
of surface, near-surface (O.5m) and deep wells (3.0 m) are used to
sample water quality as the effluent moves through the bog system.
Samples are taken on a bimonthly basis during treatment and monthly
otherwise. Samples are analyzed for temperature, pH, conductivity,
alkalinity, total and calcium hardness, chlorides, D.O., COD, BOD 5,
BOD 2,ortho and total phosphorus, NH 4, NO 2-3'KjlalNanfel
Coll orms.KedalNanfca

Pretreatment data has shown that each well cluster reacts inde-
pendently of any other. Therefore, analysis of changes in water
quality, as effluent moves through the bog, will have to be made on
a spatial and temporal basis, rather than the surface wells reacting
as a surf icial unit.

Based upon analyses through August 11, 1979, there has been no
change in water quality leaving the treatment bog. Analyses of lagoon
water versus surface wells in the bog display a substantial reduction
in phosphorus and nitrogen to within "normal" pretreatment ranges at
respective well sites throughout the bog. Chlorides, which are being
used as a trace of effluent movement within the bog have shown an
increase in the wells near the pipeline and along an unsuspected flow
path toward the outlet weir. This will be studied further to determine
whether the pipeline should be moved to another location in the bog.
No changes in water quality have been observed in the near-surface and
deep wells due to the lack of water movement in these zones.

Vegetative Study

Dr. Forest Stearns, Dr. Glenn Gutenspergen
University of Wisconsin - Milwaukee
Milwaukee, Wisconsin 53201

Funding - U.S. Forest Service

Dr. Dean Knighton, Dr. Sandy Verry, Dr. Dale Nichols
North Central Forest Experiment Station
Grand Rapids, Minnesota 55744

Funding - U.S. Forest Service

Dr. Douglas Wikum, Dr. Martin Ondrus
University of Wisconsin - Stout
Menomonie, Wisconsin 54751

Funding - University, Forest Service

The vegetative study is composed of two parts: productivity and
nutrient uptake capabilities of the predominate species of the bog,
UW-Milwaukee and Stout, and the vegetative composition of the bog,
North Central Experiment Station. The nutrient uptake study encompasses
four permanent plots within the bog as well as selected individual
trees and a small number of destructive plots in which present year
growth vegetative samples are taken for nutrient analysis. Pretreatment
data has shown that the nutrient quality of various species fall within
published data for those respective species, in their natural state.
Other vegetative studies are also taking place in the bog lagg zone
(perimeter) and downstream in the Weso Lake wetland.

Data during this year's application period have yet to be analyzed,
but will be ready for the spring research review at UW-Stevens Point.

The bog species composition study is being accomplished through
aerial and bog level stereo photography. The bog level photo points
are both within and outside the permanent plots. These pictures are
evaluated with the data collected within the permanent plots and
projected over the entire bog.

Small Animal Study

Dr. Ray Anderson, Dennis Kent
University of Wisconsin-Stevens Point
Steven Point, Wisconsin 54881

Funding - U.S. Fish and Wildlife Service

The fauna study began in the sping of 1979. This study is
designed to observe populations of small mammals, birds, amphibians,
and invertebrates within the bog system and in the upland areas
surrounding the bog. The study will note how changes in the hydrology
of the bog as well as any vegetation changes affect the movements,
composition, and numbers of species that use the wetland.

The only point of interest so far in this study is the use of
the various research boardwalks by many of the small animals. These
boardwalks were built to protect the fragile bog surface and aid the
researchers in collecting their data. They have also changed some
faunal usage patterns by making movement much easier on these mini
highways versus the pre-existing animal trails.

Water and Nutrient Budget Study

Hydrologist
Chequamegon National Forest
Park Falls, Wisconsin 54552

The water budget is rather simplified since the bog is "perched"
above the regional ground water system. The typical annual budget is:

Precipitation - Evapotranspiration - Outflow = Storage

During the discharge period, mid April through October, assuming no
effluent discharge, and assuming an average daily discharge of 0.03
cfs* the budget is:

Precipitation - Evapotranspiration - Outflow = Storage
25.9 (inches) - 20.2 (inches) - 5.8 (inches) =-.1 inch

Assuming an effluent discharge to the bog equivalent to 3/4 design
capacity (11 million gallons of effluent) during this same period and
an average discharge of 0.12 cfs** the budget would be:

Precipitation + Effluent -Evapotranspiration - Outflow = Storage
25.9 (in.) - 18.3 (in.) -20.2 (in.) -23.2 (in.) = 0.8 inches

As can be seen from this crude budget, the additional effluent
water could be added to the bog and would cause a doubling of flow
leaving the bog. The critical point here is timing the effluent
discharge to the timing of flows leaving the bog; the longer the
"contact time" for the effluent in the bog, the better the treatment.
As explained earlier these discharges of effluent to the bog are made
dependent on weather conditions and flow leaving the bog. Discharges
are also planned to coincide with peak evapotranspiration rates.
Therefore, a bulk of the discharges occur between June and September
and each discharge is planned for early in the morning.

*1/2 the average daily discharge during the period April-October 1978.
**Twice the average daily discharge during the period April-October 1978.

During the months of May, June, and July of 1979, approximately
2.8 million gallons of effluent have been applied. The weather has
been extremely wet and has reduced the number of planned discharges.
An evaluation of this year's discharge record will be made to possibly
redesign next year's "operations manual." Also, the results of a
related nutrient uptake study at the North Central Forest Experiment
Station has suggested that a greater number of discharges should occur
earlier in the year when the nutrient uptake capabilities of the plants
are greater. This alteration in the effluent discharge pattern will
be discussed at the next joint research meeting,

The nutrient budget is a joint project for members of the study
team. Since the data must be pooled from various sources the first
budget will be prepared for the Spring 1980 meeting.

Conclusion

The Drumimond Project is a multi-resource study of a spaghnum bog
and its response to the application of sewage effluent. The intent of
the project is to understand the dynamics of this type of wetland as
well as determining whether this type of wetland can be used to
effectively treat and assimilate residential sewage effluent. Up to
this time, little was known of the dynamics or treatment capabilities
of spaghnum peat wetland. This study will hopefully answer, in a few
short years, the capabilities of this type of wetland, as well as
adding to our general knowledge of the peat bog ecosystem.

If further information is desired on any part of this study,
contact the principle researcher or the Forest Hydrologist, Chequamegon
National Forest, Park Falls, Wisconsin 54552.

EFFECTIVENESS OF A WETLAND IN EASTER MASSACHUSETTS
IN IMPROVEMENT OF MUNICIPAL WASTEWATER

Donald A. Yonika, IEP, Inc., 534 Boston Post Road, P.O. Box 438,
Wayland, Massachusetts 01778

The Town of Concord, Massachusetts Sewage Treatment Plant
currently discharges secondary level wastewater to a 48 acre deep marsh
which is part of the Great Meadows National Wildlife Refuge. The
effectiveness of this wetland in further renovating effluent quality
was assessed as part of an 18 month feasiblity study on the use of
wetlands in the Commonwealth for advanced stages of wastewater treatment.
This research was conducted by IEP, Inc. for the Massachusetts Division
of Water Pollution Control.

The Treatment Plant serves 6,000 of the total town population of
18,000. Of the area serviced,, roughly 80 percent of the design flow of
I MGD is derived from residential uses and the remaining 20 percent from
light commercial, institutional and industrial use. During the actual
study period inflow to the plant average .98 MGD. Outflow as measured
by flow over the chlorine contact chamber weir, averaged .61 MGD.

The Plant presently provides an acceptable level of secondary
treatment with 83 percent suspended solids and 90 percent BOD removal.
The system basically consists of an Imhoff Tank and outdoor sand filter
beds underdrained to the chlorine contact chamber. Each of the nine
three quarter acre filter beds is periodically closed for a 24 hour
period and rested for eight days. Solids remaining on the surface are
removed and disposed of. Chlorinated secondary effluent is discharged
directly to the wetland surface of a 48 acre deep marsh that is owned
by the Fish and Wildlife Service.

The wetland functions as two units. Just below the outfall is an
approximately 6 acre section of wetland that can be described as a
combination of both shallow marsh and shrub swamp. Vegetation is
extremely dense, and almost impenetrable on foot. The effluent travels
in no distinct channel, but flows through the vegetative mat, maximizing
contact between the wastewater and wetland soils and plants. After
seeping through the 6 acre section, the wetland broadens out into a deep
marsh, with considerably more open water. Retention time during the
study period was calculated to be about 57 days. Water fluctuations
within the 48 acre wetland were only slight.during the growing season,
varying no more than two-tenths of a foot. During the winter and spring
however, fluctuations were much more severe, varying by more than two
feet over normal water elevation.

During the life of the study, the average concentrations of
wastewaters discharging to the wetland were 8.0 mg/i ammonia nitrogen,
3.1 mg/i nitrate nitrogen, .019 mg/i nitrite nitrogen, 10.0 mg/i total
kjeldahl nitrogen, 2.1 mg/i total phosphorus, 1.6 mg/i ortho phosphorus
and 38.2 mg/i for BOD.

A water sampling program was devised to attempt to quantify the
change in both concentration and loading between the secondary outfall
and the discharge point from the wetland to the Concord River. Five
sampling stations were established, as indicated on Figure 1, entitled
Water Quality Sampling Station Locations. Station 1 is the Treatment
Plant outfall. Station 2 is located at the periphery of the 6 acre
shallow marsh - shrub swamp section. Station 3 is located at the
drop-inlet discharge point from the wetland to the Concord River.
Stations 4 and 5 are located on the mainstream of the River, with
Station 4 upstream, and 5, just downstream of the Station 3 outfall in
a location where complete mixing of mainstream and wetland waters has
occurred.

Nine rounds of sampling were accomplished during the study period.
Table 1 below presents the average concentrations for selected para-
meters tested at each station.

Table 1 Water Quality Sampling Results

Ammonia Nitrogen Station mg/i

1 8.0
2 5.4
3 1.8
4 .15
5 .15

Nitrate Nitrogen Station mg/l

1 3.1
2 1.3
3 1.0
4 .67
5 .47

Nitrite Nitrogen Station mg/i

1 .019
2 .070
3 .040
4 .010
5 .010

SS5

/ / '" Ad

SS3 ~/(
WatUpper Pooli/
CONCORDII~
RIVER

�~~~~~~~~~~~~~~~~~~~~~~~-
/iiSS2 /:-
~~.~,,~''Treatment

SS4l

FIGURE 1
Water Quality
Sampling Stations Locations
A FEASIBILITY STUDY:
WETLAND DISPOSAL OF WASTEWATER TREATMENT PLANT EFFLUENT
CLIENT: MASSACHUSETTS DIVISION OF WATER POLLUTION CONTROL CONTRACTOR: IEP, INC. WAYLAND, MASSACHUSETTS
�p~~ i~~93

Total Kjeldahl Nitrogen Station mg/l

1 10.0
2 7.2
3 3.4
4 .75
5 .77

Total Phosphorus Station mg/l

1 2.1
2 .97
3 .50
4 .16
5 .17

Ortho Phosphorus Station mg/l

1 1.6
2 .67
3 .38
4 .11
5 .10

Biological Oxygen Demand Station mg/1

1 38.2
2 8.5
3 5.8
4 2.2
5 2.3

As can be readily seen, as the effluent travels through the
wetland, the concentrations of each parameter are considerably
diminished (with the exception of nitrite nitrogen).

In order to remove the influence of dilution on the results, a
loading analysis was conducted for each Sampling Station for the
parameters listed in Table 1.

Table 2 summarizes the data in terms of total pounds per day
load for each of the selected parameters at each Station during
the study period.

Table 2 Results of Loading Analysis

Ammonia Nitrogen Station Loading, Pounds Per Day
1 40
2 39
3 17
4 322
5 340

Nitrate Nitrogen Station Loading, Pounds Per Day

1 13.0
2 9.9
3 10.4
4 982
5 784

Nitrite Nitrogen Station Loading, Pounds Per Day

1 .10
2 .54
3 .39
4 17.4
5 16.6

Total Kjeldahl Nitrogen Station Loading, Pounds Per Day

1 49.8
2 52.4
3 32.5
4 1366
5 1448

Total Phosphorus Station Loading, Pounds Per Day

1 9.34
2 7.51
3 4.94
4 240
5 253

Ortho Phosphorus Station Loading, Pounds Per Day

1 7.2
2 4.6
3 3.7
4 166
5 171

Biological Oxygen Demand Station Loading, Pounds Per Day

1 188
2 63
3 62
4 3841
5 4547

Reducting further the calculations noted above, Table 3 presents
the average annual removal efficiencies of the 48 acre wetland for
the selected parameters.

Table 3

Average Annual Removal Efficiencies
For The Great Meadows Wetland

Ammonia Nitrogen 58%
Nitrate Nitrogen 20%
Nitrite Nitrogen (292%)
Total Kjeldahl Nitrogen 35%
Total Phosphorus 47%
Ortho Phosphorus 49%
Biological Oxygen Demand 67%

( ) Indicates Release

The loading data were further manipulated to see whether there
were any seasonal variations in removal efficiencies. The several
rounds of sampling results were grouped according to growing season
applicable to the Great Meadows area, from early spring to early,
mid and late growing season, to fall and early winter, and finally
to mid-winter. The data were plotted by season, and expressed as
either removal or release rate. Figure 2 is an example of the type
of seasonal variation commonly reflected by most of the tested
parameters. The results, for nitrate nitrogen show high removal
efficiencies during the growing season, and a rapid release of this
member of the nitrogen series as the plants were killed back by
frost action in the fall. This seasonal removal efficiency may be
of significant interest to water quality managers trying to reduce
in-stream concentrations of eutrophying nutrients during the high-use
summer recreational season, or when stream low flow may be a problem.

Removal efficiencies were calculated not only for the various
seasons, but also for the two different wetland subtypes found within
the Great Meadows Refuge. This data is also portrayed on Figure 2
for nitrate nitrogen. Station 1 to 2 analysis indicates function of
the 6 acre shrub swamp section. Station 1 to 3 analysis portrays the
function of the overall 48 acre predominantly deep marsh wetland
relative to seasonal removal or release rates.

Of the considerable more interest to wastewater design engineers
is data on absolute removal amounts. Figures 3 and 4 are included as
examples of the results obtained for ortho phosphorus and BOD,
respectively, relative to pounds of each removed per day per acre of
wetland. Closer inspection of either graphic indicates a significant
seasonal variation in the amount removed per acre of wetland as well
as considerable difference betwen wetland subtypes.

The mean annual uptake rate for BOD for the deep marsh section
of the wetland is 2.6 pounds per acre per day. The amount removed
by the shrub swamp - shallow marsh 6 acre section immediately adjacent
to the Sewage Treatment Plant outfall is much higher - 20.8 pounds
per acre per day.

100 89.6
80.3 Sta. 1 to Sta. 3
> 80 3.6 74.8

60 602 #A,--Sta. 2 to Sta. 3

402

z ~ ~ ~~0 0.5>st~- A --...-.-- Sta. 4 to Sta. 5

28A * Z19.61

~~~~~~~cu~ I

~ 60 6 4.8~ 64.0 | * iSta. 1 to Sta. 2
= o 640.8
6.0

80 15 128.o9r302.o
CU * 1 5 302.0
2100 .
1 2 3 ;4 5 6
Early Mid Late Fall and
Early Growing Growing Growing Early Mid
Spring Season Season Season Winter Winter

FIGURE 2
Removal Efficiency for Nitrate Nitrogen, Loading Yearly Removal Sta. I to Sta. 2 24%
(Release) Efficiencies: sta. 2 to Sta. 3 (5%)
Sta. 1 to Sta. 3 20%
Sta. 4 to Sta. 5 20%
A FEASIBILITY STUDY:
WETLAND DISPOSAL OF WASTEWATER TREATMENT PLANT EFFLUENT
CLIENT: MASSACHUSETTS DIVISION OF WATER POLLUTION CONTROL CONTRACTOR: IEP, INC. WAYLAND, MASSACHUSETTS

Pounds
per Acre
per Day
0.20 0.19
.2A - 0.04 0-03 0.05
UPTAKE .10�- 0 .03.-�.� . 0.07 Mean
0 B rin m im.i:i~i t ' Uptake
Rate

RELEASE Acre/Day
.20_... 0.15 of Deep
A Marsh
Condition 1 2 3 4 5 6
Early Mid Late Fall &
Early Growing Growing Growing Early Mid
Spring Season Season Season Winter Winter
B 1.2
1.20 -
1.10 -
1.00 -
.90 -
.80 -
UPTAKE

.50 -- 0.41 D
.........- - ------------0.43 Mean
'40--
&................ 0.32 Uptake
Rate
per
.20 - ii~l~i Acre/Day
of Shrub
.10- Swamp
0

RELEASE 10 -
.20 - -
.18

FIGURE 3

A - Ortho Phosphorus B - Ortho Phosphorus
Uptake & Release Rates Uptake & Release Rates
Stations 1 to 3 Stations 1 to 2

A FEASIBILITY STUDY:
WETLAND DISPOSAL OF WASTEWATER TREATMENT PLANT EFFLUENT
CLIENT: MASSACHUSETTS DIVISION OF WATER POLLUTION CONTROL CONTRACTOR: IER INC. WAYLAND, MASSACHUSETTS

Pounds
per Acre
per Day
15-
10-
UPTAKE 4 65
5 - 2.7
5"--*o" 2.7 _: - -':--------2.6 Mean
RELEASE"~~~'. . ..!:....: Uptake
RELEASE 5- .4 2 Rate
per
A Acre/Day
Condition 1 2 3 4 5 6 of Deep
Marsh
Early Mid Late Fall &
Early Growing Growing Growing Early Mid
Spring Season Season Season Winter Winter
B
40- 38 37

UPTAKE _- - - - _ --------------20.8 Mean
20-
i!?ii!iii~!** 1iiiiUptake
Stations15 to3Rate
10 per
10-- Acre/Day
of Shrub
5 - 2.8 Swamp
0
5-
RELEASE
10-

A- BOD B- BOD FIGURE 4
Uptake & Release Rates Uptake & Release Rates
Stations 1 to 3 Stations 1 to 2

A FEASIBILITY STUDY:
WETLAND DISPOSAL OF WASTEWATER TREATMENT PLANT EFFLUENT
CLIENT: MASSACHUSETTS DIVISION OF WATER POLLUTION CONTROL CONTRACTOR: IEP. INC. WAYLAND, MASSACHUSETTS
99

The same variable patterns hold for the nitrogen and phosphorus
series. The shrub swamp portion of the wetland removed, on the
average, .43 pounds per acre per day of ortho phosphorus, and .30
pounds of total phosphorus. The deep marsh section was considerably
less efficient, with values of only .07 and .09 pounds per acre per
day for ortho and total phosphorus, respectively.

Ammonia nitrogen at the rate of .17 pounds per acre per day was
removed by the shrub swamp section: the entire deep marsh averaged .48
pounds per acre per day. Nitrate nitrogen removal comparisons were
just the opposite for the same wetland subtypes with .50 pounds per
acre per day removed by the shrub swamp, and .06 pounds per acre per
day for the deep marsh.

These figures agree well with the majority of investigations that
have been conducted throughout the north central and north eastern
sections of the country, albeit the number of studies very limited.
Generally, however, removal rates for phosphorus and the nitrogen
series are low, in the range of one half pound per acre per day for
these nutrients, which computes to a population equivalent of only 10
to 50 people per acre of wetland, depending on whether nitrogen or
phosphorus is of concern.

of notable exception to our study and the majority of the others
are the results obtained by Dr. Maxwell Small in New York. The
absolute removal rates recorded by far exceed those obtained during
this study.

overall, our results indicate that use of wetlands for secondary
wastewater polishing may not be economically feasible in states where
larger wetlands are scarce near population centers, or where wetland
acquisition costs are high.

Thus, a need exists to identify those characteristics or components
of wetlands which, in combination, would significantly increase the
efficiency (seasonal and year-round) of wetlands to renovate secondary
waste. Construction of artificial wetlands or identification of
natural wetlands with components selected for maximizing renovating
efficiency, and matched to the particular secondary waste charac-
teristics of the plant, may make the concept of wetlands for waste-
water renovation more viable in other than rural areas.

100

WETLAND TERTIARY TREATMENT
AT HOUGHTON LAKE, MICHIGAN

Robert H. Kadlec, Department of Chemical Engineering
University of Michigan, Ann Arbor, MI 48109

For five cosecutive summers, secondary wastewater was
discharged to areas within a peatland in central Michigan.
All nitrogen and phosphorus were removed from 100,000 gallons
per day within a five acre area. The maximum water depth
increases were 10-15 cm, at the center of the discharges.
Some dissolved species, such as chloride flowed through the
treatment area with very little change; others such as pH
dropped rapidly to background levels. No soil erosion or
plant mortality occurred. Suspended solids deposited close
to the discharge. Odor problems were slight. No net virus
or coliforms were transported to the wetland. Animal
populations have not yet responded to the discharge.

101

FLOOD IRRIGATION SYSTEMS

The Houghton Lake sewage treatment plant serves a
community of population 6-8,000, which varies seasonally
for this central Michigan resort location. The developed
area is a strip bordering Houghton Lake. The septic fields
of the 1960's discharged into this shallow water body,
leading to excessive eutrophication, and leading to the
construction of a collection system and a centralized
treatment facility. This treatment plant went on stream
in late 1974.
The treatment facility consists of two aeration ponds
in series. Sludge settles to the bottom of these ponds,
and wastewater overflows to a 29 acre holding pond. The
original design calls for the water to be pumped from the
holding pond to seepage beds; or, after chlorination, to
be spray irrigated onto rye fields. The capacity of the
holding pond is sufficient for nine months storage, thus
permitting summer disposal of the treated wastewater.
Details of this system are shown in Figure 1.
This research project tested a third alternative for
disposal of the treated water from the holding pond: flood
irrigation onto a State-owned peatland. A pilot transfer
system was constructed, in June 1975, capable of pumping
100,000 gallons per day to the peatland. This system
consisted of:
(1) a buried, drainable force main from holding pond to
marsh edge;
(2) a buffer storage pond at marsh edge (for storage and
de-chlorination);
(3) an irrigation pump station at marsh edge.
From the buffer storage pond, the water was distributed
over the northeastern end of the marsh, using 1700 feet
of 3-inch agricultural irrigation pipe, laid on the
surface.
Two study sites were developed: one for a linear
trickle discharge (Site A) and one for a single point
discharge (Site B). Details are shown in Figure 2. During
the period July 24 - September 15, 1975, 2.12 million
gallons of wastewater were pumped to site A, at the average
daily rate of 40,000 gpd. Nozzles were located every 30
feet, for a total of 22 holes. These were sized to give
approximately the same flow from each hole. During the
period May 25 - September 26, 1976 a total of 10.26 million
gallons of treated effluent was pumped to the wetland and
distributed via the same 3 inch gated surface irrigation
pipe. The average pumping rate was 360 m3/day (95,000 gal/
day). on an average mound area of 65,000 m2 (16 acres),
this amounts to 3.9 cm/week, or 70 cm during the entire
summer. The only pumping problem encountered was intake
clogging by algal debris at the sewage plant holding pond.
All gates in the peatland pipe remained open, even the
smallest holes.

102

Houghton Lake Seepage Upland
Community Area Irrigation
Fields

C12

Collection Aeration Aeration Holding
System Pond Pond Pond

Cl2

c12
Removal

Figure 1. The Houghton Lake treatment system.

/ P

FuN. F

B !

Peatland Ai
1~-

cn Treatment
Plant

Figure 2. Flood irrigation system.

El~~~~

Figure 3. Aerial photographs of the wetland wastewater
treatment system at Houghton Lake, Michigan.

Figure 4.

IPORT[R RANCH PEATLA14D

) .7 T~~~~~~~~~~~~~~~~'lai paip of list wecliald area was draw~n fiato
earlal phloographo. allowing maijor Veget~ation
typ.ea. tire wastewater discharge line fromn Iti
fluhtcigk. Labe Sewer Authurity, and thet location

Lb k~~~~~1jK~~~:~~-;~~~( N. ~~~of Boilping, staciolla.

~~~~~~~~~~~~~~~~~~~~IL-
~~u. SI~3J.el0SW23
WI0

Swi'o

I I~~~~~~~ DW4 (bloleII) \

N ~~~-.. ~~0 irastwp~i wl Revision 13 Dcc~ojlser 1978
0kepWkll -35 ft..
A. 5"Alf"'41 locarloll" 'or
Iu& nod out floui

During the summer of 1977, 6.21 million gallons of
secondarily treated sewage was pumped into the marsh during
two periods of 44 and 23 days (June 3 - July 22; August 11
- September 3). This severe loading test was conducted to
observe the effects on the peat soil and plant communities.
92,000 gpd was applied using a point discharge in site B.
An approximately flat area in the sedge meadow was
chosen for Site B. A pipe support and walkway was con-
structed of untreated pine 2" x 4" in a ladder-like
fashion. The walkway supported the 3"1 aluminum pipe above
the peat soil and served as a working platform. The walk-
way protected the marsh from becoming channeled, since
previous experience showed that walking trails left visible
scars and produced a preferential path for water flow. The
walkway was 50 m in length and terminated about 5 m from
the discharge point.
During the winter of 1977-78, a large scale flood
irrigation facility was constructed. A small dechlorina-
tion pond was added at the treatment plant, together with
a 1700 gpm, transfer pump. Treated wastewater from the
dechlorination pond is pumped through a 12" diameter under-
ground force line to the edge of the Porter Ranch peatland.
There the transfer line surfaces and runs along a raised
platform for a distance of about 2500 feet to the discharge
area out in the wetland. The wastewater flowing in the
transfer line is split between two halves of the discharge
pipe which runs 1600 feet in each direction. Figure 3 is
two aerial photographs, of the treatment plant, and of the
transfer and discharge pipes looking down the Porter Ranch
wetland (toward the east). The water is distributed evenly
across the width of the peatland through small gated open-
ings in the discharge pipe. Each of the 100 gates dis-
charges approximately 16 gallons per minute, under typical
conditions, and the water spreads slowly over the peatland.
Figure 4 shows the location and overall layout of the
wastewater disposal system.
The wetland treatment system was designed by Williams
and Works, Inc., based upon research results obtained at
the University of Michigan over the five years 1972-77.
This facility has been operated by the Houghton Lake Sewer
Authority (ELSA) during the summers of 1978 and 1979. over
60 million gallons of secondarily treated wastewater were
transferred to the peatland in 1978, and over 100 million
gallons in 1979. In addition to continued research by the
University of Michigan, a small research program is
conducted by the HLSA, in addition to routine monitoring.

HYDROLOGY

The Houghton Lake peatland is a perched wetland - a
peat bed of depth varying from 1-5 meters, underlain by a
thin, possibly intermittent sand layer (10 cm), which rests

107

7 3 cm

6 1 cm

12 cm

clay ~ ~ ~ ~ ~ ~ ~2 cm

Figure 5. Approximate annual water budget for the Houghton Lake peatland.

Pipeline

n-5
~~~~~~~~~~~~10

I-~~~~~~~~~~~~im

~~~~iue6 ae et esstm tvrou d itnesfo rrgto
Co ~ ~~~~~ie 1 976

on a thick clay layer. Thus, communication with deep
aquifers is effectively blocked, and the hydrological
process of interest involve surficial water storage and
movement. Precipitation and evapotranspiration are the
transfers from and to the atmosphere; surface and shallow
subsurface flows represent transfers across the perimeter
of the wetland. Redistribution of the surface and sub-
surface water pool in the peatland occurs via overland
sheet flow, and soil suction mechanisms. Figure 5 illus-
trates a typical annual water budget for the entire wetland.
Water depths are typically in the 2-8 cm range, with
-35 cm to +35 cm being the range over 1972-77. Surface
runoff water moves into the peatland from the north and
east and leaves through the west and south. Much of the
water that goes through the peatland is surface flow and
a heavy rain may temporarily raise water levels several
centimeters on the peatland. The water level is generally
highest in the spring and lowest in the late summer.
within any one year levels fluctuate depending on rainfall.
During 1975 and 1976, depths of the water mound were
measured weekly at eight stations, and continuously at two
stations equipped with recorders in 1976; and some detailed
depth traverses were made. Water depths for 1976 are shown
in Figure 6.
The 1977 point discharge resulted in a roughly
circular mound of water of average depth 6-7 cm. Flow
through this mound occurred radially, through approximately
1/3 of the total available surface area. The advance of a
front of rhodamine dye showed water spreading radially out-
ward from the point of discharge. Although the dye did not
spread in perfectly concentric circles, there was a rela-
tively even distribution of water flowing outward from the
discharge point. The length of the start-up transient was
on the order of 5-10 days, that of the shut-down was
shorter - on the order of 1-3 days. Pumping established
� maximum center depth 6-8 cm greater than depths located
� long distance from the center of the ring.
The full scale studies of 1978-79 show similar results.
The soil elevations in the discharge area are extremely
flat, with a gentle slope toward the Dead-Horse Dam outlet.
As a consequence, the addition of wastewater along the
3,200 feet of gated irrigation pipe gives rise to a mound
of water with high points along the discharge pipe. Water
movement within the discharge area was evaluated by transect
measurements of water depth, flow rate and direction.
Sixteen float gages and four Stevens Recorders provided a
continuous record of water depth from the end of May through
October, 1978; 29 staff gages and four recorders were used
from March to September 1979.
Table 1 gives approximate water depths on three tran-
sects within the discharge area in 1978. It can be seen
that the water sheet thins in the downgradient direction,
and has variable depth as one proceeds toward the upgradient

110

Table 1. Approximate Water Depths During Wastewater
Discharge. Transects on August 30, 1978.

Meters from Leatherleaf(1) Sedge-Willow(2) Cattail (3)
Discharge Transect Transect Transect
Downgrade

0 7.0 cm 13.8 cm 7.1 cm
+ 20 7.0 cm 10.5 cm 18.3 cm
+ 50 3.4 cm 7.9 cm 28.6 cm
+100 6.3 cm 8.2 cm 30.0 cm
+200 2.8 cm 8.6 cm 29.0 cm
+300 - 5.7 cm 6.3 cm
+400 6.1 cm -
+500 - 5.2 cm -

Toward Shore
20 6.7 cm 9.7 cm 7.9 cm
- 50 9.3 cm 11.8 cm 9.0 cm
-100 5.9 cm 9.8 cm 17.4 cm
-200 3.6 cm 9.0 cm 5.8 cm
-300 - 10.0 cm 4.3 cm

(1) Located near SW 11 on Figure 4.
(2) Located near SW 12 on Figure 4.
(3) Located near SW 13 on Figure 4.

111

DYNAMIC RESPONSE OF WATER LEVEL TO IRRIGATION

18- PORTER RANCH PEATLENT - 1978
TRACE FROM A STEVENS RECORDER LOCATED NEAR THE
TEE IN THE DISTRIBUTION LINE,

16-
LU

14 -
LUw -
U

12-

- 10-

PUMP ON PUMP OFF PUMP ON

8/10 8/11 8/12 8/13 8/14 8/15
8/10 8/11 8/12 8/13 8/14 8/15
DATE

0.4 90 -

0. 3 70

60 -

0.2 -M50 -

P4
0.1- o 030 -

U
20 -

0 I 10
0 50 100 150 0 50 100 150
Distance, m Distance, m

0.4 - 0.4 r

0.3 -
0.3

0.2- ~0.2 -
Z

M0
o Z
�t~
0.1 zo1-

0 1 0
0 50 100 150 0 50 100 150
Distance, m Distance, m

Figure 8. Surface water parameters within the treatment
area on July 30, 1976.

113

10 =1

9 >1
4J 1 100

7 50

s~ I~~o 00 I I

5 0 \
0 50 100 150 0 50 100 150
Distance (m) Distance (m)

180 150

100

2 I o | I I050
60- u

0 50 100 150 0 50 100 150
Distance (m) Distance (m)

Figure 9. Surface water parameters within the treatment area
averaged from June to August. Samples were
collected weekly.

114

shore. The cattail transect was taken intentionally in one
of the isolated depressions within the wetland, leading to
the largest observed water depths at any point in the
irrigation area.
Surface water velocities ranged from 20-60 cm/min for
the sedge-willow cover type on August 30. These data are
subject to extreme variability, and reflect the fact that
only a small fraction of the peatland surface is available
for flow. This information, when coupled with the depth
information, indicates a relatively uniform moving sheet
of water proceeding through a wide variety of channels and
clumps on its course downgradient through the peatland.
The time response of water depth to the initiation of
or cessation of pumping is shown in Figure 7. When the
pump was turned off on August 11, there was an immediate
decline in water levels near the pipeline, at approximately
3 cm per day. When pumping commenced on August 14 there
was an immediate rise in water level to the old level
established by prior pumping, with the entire transient
occurring within the space of one day. Thus, the transient
response of the deepest water area, at the irrigation pipe,
is very fast. The transients at remoter locations are
considerably slower.

WATER QUALITY

The shallow tea-colored waters of this peatland are
normally acidic, and laden with dissolved organic material.
The background pH is in the range of 5-7 during summer
months. Conductivity is also low for the natural wetland,
with values in the vicinity of 280 limho/cm. With respect
to many water quality parameters, the wetland waters
contain relatively small amounts of dissolved material.
Typical background data for different depths and cover
types are given in Table 2. Subsurface interstitial water
has a somewhat elevated nitrogen content compared to
surface waters. There are also notable seasonal changes
in some dissolved materials. All data display a rather
large variability, which appears to be characteristic of
this wetland.
During the pilot scale treatment of effluent in 1975,
relatively clean water was discharged in late summer.
Concentrations of dissolved constituents in surface waters,
and 15 and 45 cm below ground, are shown in Table 3. The
data show no influence of the effluent on nutrient concen-
trations in water samples at any distance from the pipeline.
Typical 1976 patterns of surface water chemistry with
distance from the effluent discharge are shown in Figures 8
and 9. Chloride concentrations were comparatively high
within the treatment site primarily as a result of the
effluent discharge. Nitrate-nitrite-N was consistently
removed from the effluent within 30 m of the discharge

Table 2. Dissolved Nutrient Status in Several Plant
Communities. Undisturbed Houghton Lake
Peatland, 1973. (mg/Z) Means over depth
and time. Second number is standard
deviation.

Leatherleaf- Sedge- Mixed Deeper 1972
Bog Birch Willow Water Areas Rain

Approximate
No. of
Samples 230 115 90 70
NH4-N 1.9�1.7 1.1�0.8 1.5�1.4 0.29
4
NO3+NO2-N 0.066�0.035 0.056�0.023 0.060�0.038 0.45
TDP 0.066 0.077 0.098 0.040
Ca 21�8 31�12 40�26
Mg 4.0�1.6 5.9�2.3 7.4�4.2
Na 5.6�4.2 6.4�5.0 5.2�4.3
SiO2 1.4�1.2 1.3�1.1 2.0�1.8
C1 29�21 27�21 20�21

Table 3. Effluent and Wetland Water Quality on
August 22, 1975 in the Wetland Waste-
water Treatment Area.

Distance NH 4-N NO 3+NO 2-N TDP C1 K Na Ca Mg
from
source mg/k
(m)

Surface Samples
0 0.70 0.9 0.33 64 0.9 12 8 4
30 0.47 0.23 0.04 39 0.5 10 8 3
110 0.23 0.05 0.03 16 0.5 8 10 2
170 0.50 0.13 0.05 35 0.3 6 11 2

15 cm deep

30 0.52 0.20 0.04 21 0.7 6 27 4
110 0.30 0.06 0.03 22 0.1 7 20 4
170 0.42 0.18 0.04 51 0.3 6 8 1

45 cm deep
0 * * * * * * * *
30 0.75 0.25 0.04 16 0.2 3 19 4
110 0.21 0.11 0.08 63 0.4 7 19 4
170 0.81 0.15 0.21 43 1.9 11 30 6

* Not sampled.

117

during the entire pumping schedule. NH4-N concentrations
were higher at some stations in the treatment area than in
the effluent. Concentrations of total dissolved P
decreased sharply with distance through most of the
discharge period, although TDP concentrations in samples
30 m from the pipeline tended to increase through the
summer.
Total alkalinity, hardness, and pH decreased rapidly
with distance from the discharge source, while COD
increased. The increase in COD was due to high concentra-
tions of dissolved organic matter in wetland surface waters.
Heavy metal (Pb, Cu, Ni and B) concentrations were
below the detection limits of our equipment. June, July,
and August samples from the effluent and several stations
in the wetland were less than 1.0 mg/k for Pb, 0.50 mg/,Z
for Cu and Ni, and .05 mg/k for Zn.
The 1977 sampling stations were established in 6 con-
centric circles around the point discharge. Nutrient
removal was effective with background concentrations being
reached at 80 meters for TDP and at 30 meters for N03-N.
Nutrient mass balances for the point source irrigation were
calculated using water chemistry and hydrologic information.
Dissolved nitrogen storage within the first 40 meters was
82%; that for TDP was 67%.
Suspendable solids varied erratically with distance
from the discharge. Although it is difficult to accurately
sample the marsh waters for the weight parameter, the color
changes and chemical changes exhibited by the suspendable
solids with distance were obvious. The water velocity is
nearly inversely proportional to the square of the radius
in this circular geometry, leading to a sedimentation
profile which changes dramatically with radial distance.
Solid material could be entrained close to the discharge,
and redeposited later. Some of these solids were clearly
algae, as indicated by the green color of the sediments.
The full scale system was studied in similar detail in
1978 and 1979.
Transects were made throughout, and after the pumping
season, which consisted of collection and analysis of water
samples at regular intervals, beginning at the discharge
pipe and extending up to 500 meters in each direction.
Transects were made in each of the three principal cover
types: sedge-willow, leatherleaf and cattail. Samples
were also taken at some sites at 15 cm and 45 cm depths.
Measurements of conductivity, pH, dissolved oxygen and
redox potential were also made, in the field, co-incident
with the collection of transect samples. Peat samples were
collected, and the interstitial water separated and
analysed.
Water samples were typically analysed for pH, conduc-
tivity, ammonium-N, nitrate-N, chloride, total dissolved
phosphorus and various metallic cations. Ammonium, nitrate
and chloride levels were measured using specific ion

118

Figure 10.

NITROGEN (NH +) REMOVAL FROM WASTEWATER
3 0 PORE RANCH PEATLAND
TRANSECTS ON 30 AUGuST 1978

CovER TYPES
2 CATTAIL
- 0 SEDGE-WILLOW
T LEATHERLEAF
~~~~ 5~~~~~TpicalL
goe of

0~~~~~~ 0
0 .0~

A I
0 100 200 300

METERS DOWNGRADE FROM DISCHARGE

r
Figure 11.
PHOSPHORUS REMOVAL FROM WASTEWATER
PORTER RANCH PEATLAND
TRANSECTS ON 30 AUGUST 1978

COVEp 7ypcs
2- 2 CATTAIL
* * * LEATHERLEAF
; : @ SEDGE-WILLOW

o -

0 *
W 1-

c ~ ~ ~~~~ S

0 S,

o'�~~~~~~~~~~~~~~~~'

0i 100 200

METERS DOWNGRADE FROM DISCHARGE

119

Figure 12.

GROUND WATER pH
PORTER RANCH PEATLAND
8-TRANSECTS ON 30 AUGUST 1978

CATTAIL
oSEDGE-WILLOW
- 1 EATHERLEAF

0 100 200

METERS DOWNGRADE FROM DISCHARGE

Figure 13.
GROUND WATER CONDUCTIVITY
PORTER RANCH PEATLAND
800 -TRANSECTS ON 30 AUGUST 1978

400-

CATTAIL0
oSFDGE-WILLOW
LEATHER LEAF

0 ~~~~100 200 300
METERS DOWNGRADE FROM DISCHARGE

120

electrodes. Total dissolved phosphorus (TDP) was deter-
mined using a colorimetric (ascorbic acid) technique, after
digestion of the filtered water sample by sulfuric acid and
ammonium persulfate. Atomic absorption spectroscopy was
employed to determine concentrations of sodium, magnesium,
copper, iron and nickel in solution. A comparison of
surface water and interstitial water nutrient status is
given in Table 4.
Data from transects of the three cover types on August
30th are presented in Figures 10 through 13. The declines
of dissolved nutrients are quite similar to those in the
pilot-scale experiments, except for the deep water cattail
cover type. Comparable results have been obtained in 1979.
Table 5 shows neutron activation analyses of discharge
and background water samples. Within the scope of this
analysis, only sodium displayed elevated levels at the
discharge. Atomic absorption analysis shows magnesium is
also higher in the discharge area.

SOILS

The peat deposits in this wetland range from 0.5 to
3.0 meters thick. They contain wood fragments, and occa-
sional deposits of sand and clay. Chemical analyses of
Houghton muck, a histosol, reveals that the highest levels
of carbon and soluble phosphorus are found in the upper
layers of the profile. Acidity and potassium in both cover
types decrease with depth. Higher carbon but lower phos-
phorus and potassium levels are found in the leatherleaf-
bog birch cover type. The chemical composition of the
Houghton muck closely follows the characteristics of
organic soils reported by many others.
Table 6 compares the chemical composition of peat
samples at two distances from the 1976 effluent pilot
discharge. Total P, Na, and Mg were significantly (P <.05)
higher in peat samples from the 0-5 cm depth 3 m from the
discharge compared to 30 m. Total N, K, and Ca were also
higher in peat samples from the 0-5 cm depth near the pipe-
line but the differences were not statistically significant.
Soil samples were obtained in 1978 and 1979 along
transects perpendicular to the pipeline. Each core was
divided into three segments (0-5 cm, 5-10 cm, and 10-20 cm)
and analyzed for total N and P. Table 7 shows no probable
increase in P or N within the surface horizon.

VEGETATION

The vegetation in the peatland is typical of northern
peatland systems. The two dominant cover types, sedge-
willow (Carex spp. and Salix spp.) and leatherleaf-bog birch
(Chamaedaphne calyculata (L.) Moench. and Betula pumila L.),

121

Table 4. Nutrient Analysis of Surface and Interstitial
Water from Top 10 cm of Litter and Peat Soil,
Houghton Lake Wetland. Sedge-Willow transect,
30 August 1978.

Distance N-NH4 Total Dissolved
from Phosphorus
Discharge mg/Z mg/k
(m) Interstitial Surface Interstitial Surface
0 35 3.8 1.25 1.58
10 16.8 3.1 0.67 1.95
20 24.0 2.6 2.96 1.25
30 32.4 2.8 2.59 0.55
40 24.3 2.6 0.17 0.17
50 16.8 1.0 0.11 0.09
60 15.5 0.94 0.06 0.07
80 14.8 0.35 0.08 0.065
110 12.1 0.21 0.09 0.055
140 9.4 0.09 0.38 0.055
200 14.2 0.07 0.08 0.04
300 13.1 0.12 0.09 0.055
400 9.8 0.18 0.07 0.035
500 12.1 0.09 0.07 0.06

Note: Soil samples stored frozen before removing inter-
stitial water.

122

Table 5. Multi-element Analysis by Neutron Activation
Analysis. Water Samples Taken August 29,
1978 in Porter Ranch Peatland.

Background
Wastewater Water Sample
Inflow at pipe (500 m downgrade)
Element mg/k mg/k
Sm < 0.0027 < 0.0027
Lu < 0.0016 < 0.0017
U < 0.0336 < 0.0328
Th < 0.0173 < 0.0177
Cd < 0.2458 < 0.2533
Au < 0.0014 < 0.0015
Ba < 3.5962 < 3.4246
Nd < 0.5728 < 0.6625
As < 0.0826 < 0.0747
Br 0.2065�0.0112 0.2253�0.0112
Na 62.9354�2.0204 26.1746�1.3751
La < 0.0068 0.0348�0.0028
Ce < 0.0380 < 0.0366
Se < 0.0304 < 0.0321
Hg 0.0244�0.0033 0.0339�0.0034
Cr < 0.0456 < 0.0683
Hf < 0.0030 < 0.0033
Ag < 0.0154 < 0.0188
Cs < 0.0039 < 0.0054
Ni < 0.3409 < 0.5031
Tb < 0.0021 < 0.0034
Sc < 0.0004 0.0006�0.0001
Rb < 0.1399 < 0.1573
Fe 3.1278�0.6840 < 3.0348
Zn 0.2799�0.0394 6.9600�0.1249
Ta < 0.0031 < 0.0037
Co 0.0034�0.0008 0.0069�0.0009
Eu < 0.0015 < 0.0017
Sb < 0.0083 < 0.0039

123

Table 6. Total Element Concentrations in Peat Samples
From the Sedge-Willow Cover Type at Distances
From the Discharge Site. Samples Were Collec-
ted in Late June 1976. Values in Parentheses
are Standard Errors of the Mean.

Distance from
Effluent Source
and Depth of N P K Na Mg Ca
Sample % % % -g/g % %
3 m from Source
0-5 cm 2.55 0.13 0.10 210 0.17 1.30
(.08)* (.01) (.005) (36) (.01) (.06)

5-10 cm 2.85 0.11 0.07 80 0.13 1.32
(.17) (.007) (.003) (36) (.01) (.10)

10-15 cm 2.80 0.08 0.06 48 0.12 1.66
(.03) (.006) (.003) (18) (.007) (.05)

30 m from Source
0-5 cm 2.32 0.10 0.09 100 0.14 1.19
(.09) (.01) (.004) (13) (.003) (.04)

5-10 cm 2.05 0.08 0.08 10 0.13 1.12
(.38) (.01) (.01) (11) (.01) (.19)

10-15 cm 2.39 0.07 0.07 8 0.14 1.53
(.19) (.01) (.01) (3) (.01) (.17)

* n=4

124

Table 7. Nutrient Analyses of Soil Samples at Various
Distances from the Wastewater Discharge, Full
Scale Operation, Sedge-Willow Community. (% DW)

Phosphorus
Core Section, cm Distance, m
2.5 30 60
0-5 0.14 0.14 0.13
1978 5-10 0.11 0.12 0.10
10-15 0.07 0.08 0.08

0-5 0.13 0.13

1979 5-10 0.12 0.11
10-15 0.07 0.11
15-20 0.08 0.06

Nitrogen
0-5 2.38 2.15 2.54
1978 5-10 2.83 2.60 2.43
10-20 2.55 2.44 2.90

0-5 2.09 1.88

1979 5-10 2.13 2.05
10-15 2.21 2.34
15-20 2.24 1.97

125

account for about 88% of the peatland. Open water areas
(5%) provide the main habitats for a variety of aquatic
plants such as Potamogeton spp. and Utricularia spp.
Cattail (Typha latifolia L.) stands are closely associated
with depressions in the peatland and occupy 2% of the total
area. Alder (Alnus rugosa (Duroi) Spreng.) is found
primarily around the edges of the peatland and accounts for
3% of the ground cover. Aspen (Populus tremuloides
Michaux.), the primary upland cover, is occasionally found
in small stands in the peatland and these patches make up
2% of the total area. Irrigation sites A and B were
primarily in the sedge-willow community, but the full scale
project encompasses all cover types.
Data from earlier research on nutrient additions
indicated potential uptake of phosphorus and nitrogen by
the vegetative communities, including litter. The vegeta-
tion in August 1975 was studied 30 m and 150 m from the
pipeline and in a control area outside the experimental
area. The mass of live Carex spp. both above and below
ground was not significantly different among sampling
locations. Furthermore, although considerable variation
existed, the concentration of N, P, Ca, Mg, K, and Na was
not significantly higher in samples of Carex spp. leaves,
Carex spp. roots, surface litter and standing dead plant
material from experimental areas compared to control areas.
The amounts of total live, standing dead, and litter
were not significantly different (P <.05) among sample
locations in 1976. Foliar N and P concentrations of plant
species near the discharge area were higher near the pipe-
line compared to concentrations measured in 1973 and 1974.
Nitrogen concentrations in live, dead, or litter compart-
ments were not significantly different among sampling
locations. Phosphorus concentrations, however, were higher
in litter and Carex spp. leaves nearer the pipeline than
other areas. P concentrations in standing dead compart-
ments did not appear to increase as did the live and litter
compartments.
While biomass measurements were not significantly
different, cattail (Typha latifolia) dimensions were larger
in the discharge area. Cattail maximum height averaged
170 � 25.6 cm (X � s; n = 60) within 6 m of the discharge
area compared to 145 � 24.2 cm approximately 50 m from the
discharge. Circumference of the shoot base was also
significantly different with mean values of 13.3 �3.7 and
9.4 �2.95 within 6 m and 50 m of the discharge area,
respectively.
An additional indication of the response of the vege-
tation to the wastewater discharge was chlorophyll a con-
tent of sedge leaves. Sedges near (6 m) the pipeline
appeared greener compared to sedges further away. Chloro-
phyll a concentrations were 110 mg/g fresh weight of tissue
compared to 80 mg/g fresh weight away from the discharge
area.

126

In the full scale project, above ground standing crop
in the sedge community near the pipeline increased in
response to the nutrient additions. Measurements taken in
1978 after cessation of effluent discharge showed that the
total above ground standing crop was approximately twice
as much at the pipeline than at stations 90 m from the
source of wastewater. In 1979, increased standing crops
were prevalent out to and beyond 90 m.
Dramatic changes in species composition have not
appeared in the early years of the discharge, but baseline
data has been taken for future reference.
A zone of foliar N and P enhancement has developed,
extending to and beyond 90 meters from the pipeline. The
mass of N and P in the above ground standing crop decreased
with distance in 1978, but not in 1979. (Table 8.)
Nitrogen and phosphorus in the litter were measured as
percent of dry weight. The data in Table 9 shows increased
P near the discharge in 1978, but not increased N. In
1979, the zone of increased P extended to and beyond 100 m.

ALGAE

The response of the algal community of the Porter
Ranch Wetland to nutrient enrichment was studied by 3
methods during the summer of 1976. Continuous flow bio-
assay chambers were designed and constructed to measure
in situ increases of Cladophora sp. dry weight and to
provide continuous monitoring for potential toxic dis-
charges. Aquatic community metabolism was measured by the
examination of diurnal oxygen fluctuations. Productivity
estimations for epiphytic algae were made by determination
of Chlorophyll a concentrations on artificial substrates
of known surface area. This method was also used to
determine the effects of increasing water depth in epi-
phytic algal production.
Nutrient uptake by the algal community was estimated
by calculation procedures based on measurements of nutrient
concentrations of the bioassay algae, coupled with bioassay
growth rate estimates.
Growth rate of the bioassay algae at the pipeline
(nutrient enriched) study site was 2656 mg dry wt m-2 day-1
for the period between June 12, 1976 and July 3, 1976.
Growth rates in the control area were 85 mg dry wt m-2
day-1, for the same time. The standing crop of Cladophora
at the enrichment site was 41 g dry wt m-2 on July 7, 1976.
On the same date, the standing crop of Cladophora at the
control site was 5 g dry wt m-2.
Aquatic community productivity as measured by the
dissolved oxygen method were an average of 225% higher in
the discharge site, compared to the control site.
Dissolved oxygen values in excess of 250% saturation were
commonly recorded in the surface water of the discharge

127

Table 8. Standing Crop Biomass and Nutrient Status in the Sedge-Willow
Community at Various Distances from the Discharge. Ranges of
Data Over Triplicates are Typically �30%.

Distance Biomass Nitrogen Phosphorus
gm DW/m2 gm/m2 gm/m2
9-21-78 8-29-79 9-21-78 8-29-79 9-21-78 8-29-79
2.5 525 556 10.6 10.2 1.7 2.2
30 380 620 6.2 9.5 1.3 1.7
60 190 - 2.8 - 0.6 -
90 270 712 3.9 10.8 0.4 1.92

Table 9. Nutrient Concentrations in Litter, Sedge-Willow Community.
(% DW)

Distance from Nitrogen Phosphorus
Discharge, m 8/30/78 8/29/79 8/30/78 8/29/79

0 1.73 2.10 0.22 0.26
30 2.20 2.40 0.22 0.31
60 1.87 - 0.10 -
80 2.58 - 0.11 -
100 - 2.25 - 0.52
110 2.38 - 0.11 -

site. In the late summer, simultaneous dissolved oxygen
consumption in full sunlight, pH values in excess of 10.0
and dissolved 02 supersaturation strongly suggest that
photorespiration of the algal community plays an important
part in the seasonal pattern of algal productivity under
conditions of nutrient enrichment.
There was no significant difference in chlorophyll a
concentrations at study sites in the wetland.
Nutrient uptake rates of the bioassay algae were 12
mg p m-2 day-1 and 55 mg N m-2 day-1. End of the growing
season values for total nitrogen and phosphorus content of
the bioassay algae were 4.3 g N m-2 and 0.96 g P m-2,
respectively.

PATHOGENS

A variety of surface water samples were analyzed for
both total coliforms and fecal coliforms by the most
probable number method, both during the 1975 and 1976
irrigation seasons, and during 1974. The 1974 sampling
program was intended to provide background data on
coliforms in the wetland, its inlets, outlets, and
neighboring receiving water bodies. The results of this
work are given in Table 10.
Coliform levels at all locations at all times dis-
played considerable variability. The sewage plant aeration
ponds displayed the expected high levels, but the sewage
plant holding pond, from which wastewater was pumped,
showed fairly low levels during all pumping periods. At
no time during the summers of 1975 through 1979 did the
pumped water exhibit more than the legally allowable 200
fecal coliforms per 100 ml of water. This information
allowed the operator to refrain from chlorination during
all irrigation periods.
The fecal coliform levels were considerably lower than
total coliform levels both during the background year of
1974 and during the pumping years of 1975 and 1976. Within
the natural wetland, fecal levels ranged from 0 to 20% of
the total coliforms reported in Table 10. Within the study
sites in 1975 and 1976, the percent fecal coliform ranged
from 0 to 50%.
It is known that raw sewage contains human enteric
viruses, and that sewage treatment plants reduce these con-
centrations. In late summer 1977, a field test was under-
taken to determine the profile of virus concentrations at
various stages of wastewater treatment, and in the wetland
irrigation site. Samples were collected and preconcen-
trated in Michigan, and subsequently analyzed at the
University of New Hampshire under the direction of
Dr. Theodore G. Metcalf.
The results of these analyses are given in Table 11.
The recoveries of virus from the standards was not good,

130

Table 10. Total Coliform Bacteria, Houghton Lake Wetland.
(MPN method) (Number per 100 ml) (Averages)

Natural Natural Interior Points Discharge Discharge Receiving
Inflows Outflows (Control) Area Water Bodies
1974
4/21 - - 1100 250
5/28 390 264 7122 1393
7/14 270 435 452 860
8/9 110 120 92 8070
8/27 585 170 563 640
9/30 2765 6585 1960 3400

1975
5/17 140 20 20 none 270 25
7/4 270 80 140 none 3667 183
8/15 140 110 20 53 25 83

1976
6/4 - - - 80 483 -
7/1 1700 715 2787 710 7623 1700
7/12 - - - 850 1330 -
7/27 - - - 965 1685
8/24 - - - 40,000 46,000

Table 11. Recovery and Identification of Virus Isolants
from the Houghton Lake Sewage Treatment Plant,
Pilot Irrigation Site B, and an undisturbed
Wetland Site. (50 gallon samples)

Sample Virus Isolant Number Isolants Isolant
Recovered Recovered Identity
(PFU)

Aeration Pond
#1 + 1 Echovirus 32
Aeration Pond
#2 + 1 Echovirus 32
Holding Pond/
Discharge 0 0
20 meters from
Discharge 0 0
40 meters from
Discharge 0 0
Wetland
Background 0 0
Standard 1
(2500 PFU) + 14
Standard 2
(2500 PFU) + 142

132

in that only 1.5% of the low concentration was recovered.
The estimated analytical recovery (New Hampshire) was 25%,
leading to an estimated sampling recovery (Michigan) of 6%
for the low concentration levels encountered. This is not
surprising in view of the extreme difficulty of sample
collection and pre-processing in the wetland situation,
and the unavoidable delays in sample transport and storage
occasioned by the large distances between the site and the
laboratories.
A study of the full scale site in fall 1978, conducted
entirely within Michigan, yielded quite different results.
Both reovirus and poliovirus were found at all locations
in the treatment plant and the wetland, with a hundred-fold
reduction occurring on passage through the treatment plant.
The wetland (control site) and the treated wastewater
exhibited the same total virus. The surface water of the
wetland was experimentally determined to be hostile to
poliovirus, but not to reovirus.

VERTEBRATE AND INVERTEBRATE FAUNA

Data on wetland wildlife populations from 1975-1977
consists of mist net caputres of birds, transect data for
herptiles and field observations for larger mammals. There
were no dramatic changes in either species abundance or
species composition of wetland birds between the summers of
1973 and 1975. in 1973 (background) mist netting resulted
in the capture of .54 birds per mist net hour. in 1975
(pilot project) mist netting yielded a capture rate of .38
birds per mist net hour. Species composition of the mist
net captures was similar during both years, with swamp
sparrows and yellow throats comprising 79% of the birds
caught in 1975 and 62% of the birds caught in 1973.
During the pumping season of 1976, one new muskrat
lodge was established near the pilot area discharge site,
since this was the only standing water available. After
pumping ceased, the lodge was abandoned. White-tailed deer
were the only other mammals observed in the pilot area of
the marsh during 1975-77. Deer sightings remained at
constant frequency during this period.
In 1978, under the auspices of the HLSA, several
methods were used in the collection and enumeration of the
vertebrates and invertebrates of the marsh in the area of
discharge. Selective dipnetting, in water zones, was used
to collect aquatic insects prior to pumping. Wire mesh
cones located in front of the discharge pipe collected the
influx of invertebrates and fish from the treatment plant
holding ponds. Core extractions were used to determine
zone effects of aquatic insects and invertebrates. Non-
aquatic insects were collected in sweepnet samples from
the various habitats in the area of discharge. Shading and
basking platforms were set up to provide observation sites

133

for herps, minnow traps were useful in entraping amphibians
and fish. Small rodents were collected in live traps,
larger mammals by observation only.
This research is continuing in 1979, with the goal of
understanding long term impacts on these populations. No
significant effects have yet been quantified; it is still
too early in the life of the project.

SUMMARY AND CONCLUSIONS

For five consecutive summers, secondary wastewater has
been discharged to a peatland in central Michigan. Thus
far, this is a successful means of advanced treatment.
Results indicate that this is indeed an effective means of
nutrient removal. The wetland is large (7 square kilo-
meters), and therefore retained 100% of all added nutrients.
But further, all nitrogen and phosphorus were stored or
removed within a five acre area, at a discharge rate of
100,000 gallons per day; and within a 50 acre area at
1,000,000 gpd. The maximum increase in water depth was
15 cm at the center of a single point discharge. During
the 1976 drought, the discharge created the only remaining
surface water.
Nutrient fronts appear to be moving slowly downgra-
dient.
inactive dissolved species, such as chloride, flowed
through the active area with very little change. The pH
of the added water was high compared to the slightly acid
wetland waters, but dropped rapidly to background levels
as the water traveled across the wetland. There was a
similar pattern for conductivity: high entering values,
dropping rapidly to background.
Neither a linear discharge, through numerous gates in
irrigation pipe, nor a point discharge from a single pipe,
caused any soil erosion or plant mortality. Suspended
solids from the treatment plant deposited very close to
the area of discharge, and were not transported with the
wastewater. Visual effects were minimal: itensified green
color in plants, and slightly (5-10 cm) deeper water near
the discharge. Odor problems were slight or non-existent.
The wastewater was of quite low heavy metal content, and
hence no information on this potential contaminant was
obtained. Coliform bacteria and virus were present in both
the discharge and in the natural wetland in comparable
numbers.
The animal populations exhibited little response to
the discharge. There was no change in bird activity or
numbers, nor was there noticeable effect on larger mammals.
The fate of the added nutrients is in the soil, litter
and plants near the discharge. Exact proportions cannot be
determined, because of the large natural pool of these
materials. Based on lab studies, it is clear that processes

134

such as sorption, ion exchange, and precipitation remove
some added constituents, such as phosphorus. It is quite
likely that microbial denitrification plays an important
role in nitrogen removal. Uptake by algae and vascular
plants provides at least a temporary storage for some
nutrients, and perhaps a permanent storage of some fraction
of the added material.
This peatland can accept treated wastewater during the
summer months without noticeably changing the character of
the wetland over periods of one to two years. The nutri-
ents (nitrogen and phosphorus) are removed, but some dis-
solved materials (sodium and chloride) are not.

ACKNOWLEDGMENTS

The Houghton Lake Wetland Treatment System was built
and placed in operation during the first six months of
1978. An operation and maintenance plan has been developed,
and the system operates successfuly. This remarkable
achievement was made possible by the excellent cooperation
of the National Science Foundation, Environmental Protec-
tion Agency, Michigan Department of Natural Resources, the
U.S. Fish and Wildlife Service, Roscommon County, the
Houghton Lake Sewer Authority, Williams and Works, Inc.,
and the University of Michigan.
This paper is based on the work of many people, in-
cluding all those referenced in the Related Publications
list. In addition, University of Michigan field operations
were successfully guided by Mr. Richard J. Kruse.

RELATED PUBLICATIONS

1. Progress Reports:

Kadlec, John A., Kadlec, Robert H., Parker, Peter E., and
Dixon, Kenneth R. "The Effects of Sewage Effluent on Wet-
land Ecosystems." Progress Report. July 1, 1972 to April
1, 1973.

Kadlec, John A., Kadlec, Robert H., and Richardson, Curtis
J. "The Effects of Sewage Effluent on Wetland Ecosystems."
Progress Report. April 1, 1973 to March 1, 1974.

Kadlec, John A., Kadlec, Robert H., and Richardson, Curtis
J. "The Effects of Sewage Effluent on Wetland Ecosystems."
Semi-Annual Report No. 1. May 1974.

Kadlec, Robert H., Richardson, Curtis J., and Kadlec, John
A. "The Effects of Sewage Effluent on Wetland Ecosystems."
Semi-Annual Report No. 2. November 1974.

135

Kadlec, Robert H., Richardson, Curtis J., and Kadlec, John
A. "The Effects of Sewage Effluent on Wetland Ecosystems."
Semi-Annual Report No. 3. May 1975,

Kadlec, Robert H., Richardson, Curtis J., and Kadlec, John
A. "The Effects of Sewage Effluent on Wetland Ecosystems."
Semi-Annual Report No. 4. November 1975.

Kadlec, Robert H., Tilton, Donald L., and Kadlec, John A.
"Feasibility of Utilization of Wetland Ecosystems for
Nutrient Removal from Secondary Municipal Wastewater Treat-
ment Plant Effluent." Semi-Annual Report No. 5. June 1977.

Kadlec, Robert H., Hammer, David E., and Tilton, Donald L.
"Wetland Utilization for Management of Community Waste-
water." Status Report. October 1978.

Kadlec, Robert H., Hammer, David E., Tilton, Donald L.,
Rosman, Lisa, Yardley, Brett. "Houghton Lake Wetland
Treatment Project." First Annual Operations Report.
December 1978.

Kadlec, Robert H., Tilton, Donald L., and Schwegler,
Benedict R. "Three-year Summary of Pilot Scale Operations
at Houghton Lake." Report to the National Science Founda-
tion. February 1979.

Kadlec, Robert H., Ed., "Wetland Utilization for Management
of Community Wastewater." 1978 Operations Summary. March
1979. Report to NSF-ASRA.

2. Monographs:

Dixon, K. R., and Kadlec, J. A. "A Model for Predicting
the Effects of Sewage Effluent on Wetland Ecosystems." The
University of Michigan, Ann Arbor, Publication Number Three,
February 1975.

Richardson, C. J., Kadlec, John A., Wentz, A. W., Chamie,
J. P. M., and Kadlec, Robert H. "Background Ecology and
the Effects of Nutrient Additions on a Central Michigan
Wetland." The University of Michigan, Ann Arbor, Publica-
tion Number four, June 1975.

Parker, P. E., Gupta, P. K., Dixon, K. R., Kadlec, R. H.,
Hammer, D. E. "REBUS - A Computer Routine for Predictive
Simulation of Wetland Ecosystems." August 1978.

Schwegler, B. R., and Kadlec, R. H. "Wetlands and Waste-
water." Pamphlet. 1978.

136

3. Theses:

Bergland, Mark S. "Foraging Ecology of the Female Red-
Winged Blackbird." M.S. Thesis. The University of Michi-
gan, Ann Arbor, 1975.

Bergland, Mark S. "Foraging Behavior of Red-Winged Black-
birds Breeding in a Wetland Ecosystem." Ph.D. Thesis.
The University of Michigan, Ann Arbor, 1978.

Chamie, Jim P. M. "The Effects of Simulated Sewage
Effluent upon Decomposition, Nutrient Status and Litter-
fall in a Central Michigan Peatland. Ph.D. Thesis. The
University of Michigan, Ann Arbor, 1975.

Croson, Susan C. "Distribution and Abundance of Insects in
a Wetland Ecosystem." M.S. Thesis. The University of
Michigan, Ann Arbor, 1975.

Dixon, Kenneth R. "A Model for Predicting the Effects of
Sewage Effluent on Wetland Ecosystem." Ph.D. Thesis.
The University of Michigan, Ann Arbor, 1974.

Gupta, Prem K. "Dynamic Optimization Applied to Systems
with Periodic Disturbances." Ph.D. Thesis. The University
of Michigan, Ann Arbor, 1977.

Maguire, Lynn A. "A Model of Beaver Population and Feeding
Dynamics in a Peatland at Houghton Lake, Michigan." M.S.
Thesis. The University of Michigan, Ann Arbor, 1974.

Parker, Peter E. "A Dynamic Ecosystem Simulator." Ph.D.
Thesis. The University of Michigan, Ann Arbor, 1974.

Scheffe, Richard D. "Estimation and Prediction of Summer
Evapotranspiration from a Northern Wetland." M.S. Thesis.
The University of Michigan, Ann Arbor, 1978.

Schwegler, Benedict R. "Effects of Sewage Effluent on
Algal Dynamics of a Northern Michigan Wetland." M.S.
Thesis. The University of Michigan, Ann Arbor, 1978.

Wentz, W. Alan. "The Effects of Simulated Sewage Effluents
on the Growth and Productivity of Peatland Plants." Ph.D.
Thesis. The University of Michigan, Ann Arbor, 1975.

4. Utilization Reports:

Kadlec, Robert H., Tilton, Donald L. "Monitoring Report
on The Bellaire Wastewater Treatment Facility." Utilization
Report No. 1. August 1977.

137

Kadlec, Robert H., Tilton, Donald L. "Monitoring Report on
the Bellaire Wastewater Treatment Facility," Utilization
Report No. 2. March 1978.

Kadlec, Robert H., "Monitoring Report on the Bellaire
Wastewater Treatment Facility." Utilization Report No. 4.
February 1979.

5. Papers:

Croson, S. and Witter, J. A. "Distribution and Abundance
of Mosquitoes in a Wetland Ecosystem." North Central
Branch, Entomological Society of America, Proceedings.
1975.

Haag, Robert D., "The Hydrogeology of the Houghton Lake
Wetland." The Michigan Academician, 1979. In progress.

Kadlec, R. H. "Wastewater Treatment via Wetland Irrigation:
Hydrology." Proceedings of the Waubesa Conference on
Wetlands, Madison, Wisconsin, 1978.

Kadlec, R. H., Tilton, D. L. "Nutrient Dynamics in
Effluent-Irrigated Wetlands." Proceedings of the Kissimmee
Symposium on Freshwater Wetlands, Tallahassee, Florida,
1978.

Kadlec, R. H., Tilton, D. L. "The Utilization of Fresh-
water Wetlands for Nutrient Removal from Secondarily Treated
Wastewater. 1979. Journal of Environmental Quality. In
progress.

Kadlec, R. H., Tilton, D. L. "The Use of Wetlands as a
Tertiary Treatment Procedure." CRC Press. 1979. In press.

Kadlec, R. H. "Wetlands for Tertiary Treatment." Pro-
ceedings of the National Symposium on Wetlands, Lake Buena
Vista, Florida. November 1978. In progress.

Kadlec, R. H., Kadlec, J. A. "Wetlands and Water Quality,"
Proceedings of the National Symposium on Wetlands, Lake
Buena Vista, Florida. November 1978. In progress.

Kadlec, J. A. "Nitrogen and Phosphorus Dynamics in Inland
Freshwater Wetlands," Proceedings of the Symposium on
Waterfowl and Wetlands, Midwest Wildlife Conference.
Madison, Wisconsin, 1978. In press.

Parker, Peter E., and Kadlec, Robert H. "A Dynamic Eco-
system Simulator." Paper presented at A.I.Ch.E. 78th
National Meeting, Salt Lake City, August 1974.

138

Richardson, C. J., Tilton, D. L., Kadlec, J. A., Chamie,
J. P. M., and Wentz, W. A. "Nutrient Dynamics in Northern
Wetland Ecosystems." In R. E. Good, R. L. Simpson, and
D. F. Whigham, Eds. Freshwater Marshes: Present Status,
Future Needs. Academic Press, N.Y., 1978.

Tilton, Donald L. "Wastewater Treatment via Wetland
Irrigation: Nutrient Dynamics." Proceedings of the
Waubesa Conference on Wetlands, Madison, Wisconsin, 1978.

6. Conference Proceedings:

Tilton, D. L., Kadlec, R. H., and Richardson, C. J. "Fresh-
water Wetlands and Sewage Effluent Disposal." Proceedings
of the NSF/RANN Conference on Freshwater Wetlands and
Sewage Effluent Disposal. University of Michigan, Ann
Arbor, Michigan, May 10-11, 1976.

Sutherland, Jeffrey C. and Kadlec, Robert H., Eds. "Fresh-
water Wetlands and Sanitary Wastewater Disposal." Confer-
ence Abstracts, July 1979.

139

ENGINEERING, ENERGY AND EFFECTIVENESS FEATURES
OF MICHIGAN WETLAND TERTIARY WASTEWATER
TREATMENT SYSTEMS

T. C. Williams, Chairman of the Board, Williams & Works, 611 Cascade West
Parkway, S.E., Grand Rapids, Michigan 49506

J. C. Sutherland, Studies Manager, Williams & Works

ABSTRACT

Two markedly different Michigan wetlands are receiving pond stabilized
secondary treated non-chlorinated wastewater. Both operations result in
removal of 98%-100% of phosphorus through contact with reactive soils.

At Vermontville (42037'N, 85001'W) flood irrigation fields (11.5 acres)
overgrown with volunteer wetland vegetation (mainly cattail) treat and dis-
pose of wastewater principally by slow seepage (4 in./wk) through phosphorus-
adsorbing clayey-silty glacial till. Occasional uncontrolled runoff of
wetland surface waters releases phosphorus, BOD, and suspended solids in
concentrations slightly above permitted limits. Seepage wetlands offer
potential advantages compared to upland spray irrigation for small commun-
ities. Savings of 25% and greater on capital plus land costs can be expected
for flow below 0.1 MGD average flows. Field maintenance may not be needed,
and irrigation energy costs need be no higher than those for surface irriga-
tion of uplands.

At Houghton Lake (44018'N, 85050'W), natural state-owned wetlands (600 acres)
treat and dispose of wastewater by overland flow across a reactive peat sub-
strate. Construction and maintenance in 1978 involved negligible ecological
impact. Construction was done in the dormant months between March and June.
The wetland transmission and irrigation pipelines are strapped to a wooden
walkway suspended 2.5 ft above the wetland on pole pilings anchored in clay.
The cost of the wetland wastewater distribution system was $21.00/ft (1979
dollars). Irrigation electrical energy costs were approximately $7.21 in
1979. The wetland capital and land costs represent savings of approximately
$1 million compared to upland irrigation.

141

FOREWORD

The engineering-related features of the Houghton Lake and Vermontville,
Michigan, wetland wastewater treatment systems are presented and discussed
herein. The environmental responses and details of wetland water quality
at the Houghton Lake site are presented in this volume in a separate paper
by Robert H. Kadlec. The phytosociology, phenology, and wildlife habitat
attributes of the Vermontville wetland site were studied by Frederick B.
Bevis and have been previously distributed and presented (1,2). Some of the
included engineering documentation related to Vermontville was distributed
or presented earlier this year (1,3) and similarly for Houghton Lake (4,5).
Additional background on the Houghton Lake facility is presented in reference
15.

142

PART I: VERMONTVILLE

INTRODUCTION

The municipal wastewater treatment system at Vermontville, Michigan (popula-
tion 975), consists of two facultative stabilization ponds of 10.9 acres,
followed by four diked surface (flood) irrigation fields of 11.5 acres con-
structed on silty-clayey soils. The system is located on a hill with the ponds
uppermost and the fields at descending elevations (Figures I and 2). Now in
their seventh year of operation, the fields are nearly overgrown with volunteer
emergent aquatic vegetation, mainly cattail.

The Vermontville system is one of several pond and irrigation systems constructed
for sanitary wastewater treatment in the late 1960's and early 1970's in Michigan.
It was one of the first such systems to go into operation in this state. There
was one very specific need among others which led to the introduction of upland
irrigation systems in Michigan. That need was phosphorus (P) removal. in 1968
the Lake Michigan Enforcement Conference of the FWPCA (the EPA forerunner) deter-
mined that communities in the Lake Michigan Basin must remove 80% of the P from
sanitary wastewater before discharging it to streams.

Vermontville's system was conceived and designed with phosphorus removal and
economy of operation in mind. The ponds would receive raw wastewater alter-
nately with a week-on, week-off schedule. The upper pond (PI, Figure 2), has
separate discharge lines into fields F1 and F2 and the lower pond (P2) has
separate discharge lines into fields F3 and F4. Pond-stabilized wastewater
would be released into each field by gravity flow through 10-in, main and 8-in.
manifold pipe having several ground level outlets in each field. Irrigation of
terrestrial grasses would take place during six of the spring-summer-fall months.
Up to 4 inches of wastewater applied each week would flood the fields briefly
until the water seeped away. Should the water level exceed 6 in. or so, water
would overflow to the next field by means of a standpipe drain. It was expected
that all applied water would seep into the ground before leaving the treatment
area.

The system's actual operation and the general hydraulic behavior of the fields
are essentially as conceived; although in actual operation the fields often do
overflow when wastewater is being released into them, or following hard rainfall,
nearly all of the irrigated wastewater seeps into the ground. But there are some
significant departures from the conceived system. Water stands in the fields for
hours or days at a time, and the fields are heavily overgrown with wetland vege-
tation. Actually, cattails began to establish a year before irrigation was begun
and while the ponds were being filled for the first time. Also, although the
final field (F4) is never irrigated, there is at all times a surface discharge
from F4 into a stream. At most times this surface discharge is dominantly re-
cycled wastewater, which is wastewater that has seeped through the ground from
the upper fields, and then re-emerged as springs into F4. The quality of the
spring water is very high. The spring water is occasionally augmented with sur-
face wastewater overflow from F3, under which condition the quality of the surface

143

HOUGHTON

LAKE

cGRrND LAKE
RA! DS. -ODESSA \
|" " sLANSING
VERMONTVILLE ETROIT
/xPAW PAW LEONwi
-TOWNS b HIP
FIGURE i, �MICHIGAN LOCATIONS WHERE MUNICIPAL WASTEWATER-
WETLAND EFFECTS ARE BEING INVESTIGATED
144

� �~~~~~~~~~~~~~~~~4

i �-

FIGURE 2. WASTEWATER STABILIZATION PONDS (P) AND IRRIGATION FIELDS (F): VERMONTVILLE.

discharge from F4 is not as high as it is required to be. Both of these de-
partures - wetlands in place of terrestrial vegetation and the related existence
of the surface discharge of variable quality, invite questions about the econo-
mics and effectiveness of treatment attending incidental or deliberate inclusion
of seepage wetlands. In 1978, the National Science Foundation granted us funds
to investigate the Vermontville system to identify any features which might be
advantageous in economical wastewater treatment for small communities (NSF ENV-
20273).

SOILS AND THE RATE OF SEEPAGE

The treatment site is located on glacial till. Extensive cutting and filling
of the till soils were necessary to rough grade the irrigation fields at the
time of construction. Numerous borings taken in the irrigation fields reveal
the upper 4 112 ft of inorganic soils to be sandy clay, silty clay, and clayey
silt, with subordinate clay, clayey sand, silty sand, and fine-gravelly variants
of most of the forenamed textures.

Fifteen (15) split-spoon soil samples from the upper 4 1/2 ft including most
of the mixed soil types named above were tested for hydraulic conductivity
(h.c.) in the laboratory using falling-head permeameters. The observed range
of the lab h.c. is 1.3 x 10-8 cm/sec for an impure clay to 1.4 x iO-5 cm/sec
for one impure sand sample. Among all samples, only the impure sand showed a
higher h.c. than 5.8 x 1iO7 cm/sec.

The seepage wetlands transmit wastewater at the observed average rate of at
least 4 in./wk, or 2.5 x iO-5 cm/sec, similar to the h.c. of the impure sand
sample tested. Yet a total of 27 borings in the overall treatment site indicates
that sand as clean as the impure sand is a minor soil type here. The higher
actual field permeability compared to the lab samples could be due to compaction
of soil samples in the lab in spite of counter-efforts, or to the (undiscovered)
occurrence of sandy zones which may be areally minor, but effective as seepage
areas. Equally likely is residual looseness within the extensive volumes of
clayey fill in the wetlands, with attendant random networks of irregular openings
which facilitate seepage. Most areas of filling are low-lying compared to the
cut areas, and have been so since shortly after final grading. This feature
does not, however, appear to shed useful light on the state of openness of the
fill. One, or a combination of the named factors, could be significant with
respect to the observed rate of seepage.

ENVIRONMENTAL WATER QUALITY

The average quality of the influent, pond effluent, wetland water, ground water
and final surface overflow is shown in Figure 3. Incidental to the more impor-
tant quality aspects, but requiring explanation nevertheless, is the dilution
of wastewater (chloride) as it flows across the system. Chloride decreases
persistently from 280 mg/l in the influent to 123-124 mg/l in the ground and
final overflow waters. Heavy snow diluted the influent wastewater accumulating

146

WATER QUALITY
CI .....280 mg/I ..207 ..157 STRICT
NH3'N.. 37 .....5 .....2.5 2.0 LIMITS
N03N .....1.3 , ..... 1.0 1.2 CI 123
TKN ... 81 .....6.5 ....5.0 P 0.64 (0.5)
P 5.3 , ..... 1.8 ....2.1 BOD 5.5 (4,10)
> PONDS /-'.. VVWETLAND SS 20 (5,15)
INFLUENT FIELDS . ',
67,000 GAL/DA So
SOIL i ~ k, "0?/cO
Cl 124 FILTER '/
NH3'N 0.7
N03-N 1.4 STREAM
TKN 3.7
I 0.04 3GROUND WATER

FIGURE 3. ENVIRONMENTAL WATER qUALITY: VERMONTVILLE

in the ponds between late fall, 1977 and June, 1978, such that the average pond
effluent showed 207 mg/l Cl over the June-to-December 1978 irrigation season.
Rainfall 50% above normal, and the coincidence of several sampling visits with
rainy periods, account for the 30% dilution of wetland standing water relative
to pond effluent. The seepage-derived ground water is 25% to 30% diluted with
respect to wetland water because of mixing with ambient ground water. The final
surface overflow consists of soil-filtered wastewater derived from the three
upper wetlands which is further diluted by rainwater in the fourth and final
field.

Phosphorus is higher in the wetland fields than in the pond effluent. Even
with dilution, total phosphorus increases from 1.8 mg/l (pond discharge) to
2.1 mg/l in the wetland waters. Decomposing detrital organic matter is a likely
source of additional P. Also, the standing wetland crop loses P over the ir-
rigation season. Some amount of the lost P is perhaps stored in plant roots
and rhizomes, but much of the lost P is likely released directly into the
wetland water. Approximately 97% removal of P occurs between the wetland fields
and the ground water, which is sampled from monitoring wells placed at depths
ranging from roughly 10 ft to 25 ft below the wetland floors. Most removal
of P occurs in the upper 3 ft of soils judging from a small number of porous
cup lysimeter samples which average 0.1 mg/l total P and 0.06 mg/l ortho-P,
with ranges of 0-0.3 mg/l and 0-0.2 mg/l, respectively. The average removals
of P effected in the upper 3 ft of soils are approximately 95%. Phosphorus
is reduced to 0.04 mg/l in the ground water which is well below local NPDES
stream discharge requirements of 0.5 mg/l P.

The immediate foregoing information documents the wetlands as an incidental
factor in the treatment effected through the flood irrigation system, which
reduces P to values well below the required 20% quantity and 0.5 mg/l concen-
tration limits.

If the wetland waters were permitted to overflow into a receiving stream, the
NPDES limits for P of 0.5 mg/l (final column of numbers, Figure 3) could not
be met. In fact, occasional surface overflow of wastewater from F3 into F4
causes the average final overflow from F4 to be slightly in excess of the NPDES
limits for P, BOD and SS (final two columns of numbers, Figure 3). Neither BOD
nor SS was measured in the ground water samples. General absence of literature
and first hand data which would imply significant levels of BOD and SS remaining
in sanitary wastewater filtered through several feet of fine textured soils
made us believe the BOD and SS would be unremarkable in the ground water.

The F4 overflow quality data support data obtained by others under somewhat
different circumstances which suggest that the flow-through process in wetlands,
absent filtering of wastewater through native soils, might not provide sat-
isfactory removal of phosphorus and other potential pollutants (references 6
through 9).

148

OPERATION AND MAINTENANCE

The Seepage Area

The wetland fields have not been maintained since they were put into use in 1973.
They seem not to require maintenance. Maintenance factors which characterize
upland irrigation such as encrustation of the uppermost soil surface (tightening
of soils), and accumulation of the standing crop (necessitating removal to control
animal pests, for example) do not appear to be present.

The potentially harvestable wetland biomass (mostly cattail) is reduced to a
cattail straw mat over the dormant months. The wastewater wetlands may act
similarly to natural seepage wetlands established on glacial soils which have
apparently seeped effectively for centuries. The absence of fine detrital
inorganic sediments is a plausible common factor in the seepage longevity of
both the wastewater-developed and natural seepage wetlands. Mineral silt and
clay in the raw wastewater may effectively settle out in the stabilization
ponds. The irrigation inlet pipe inverts are only 1.5 ft above the sloping (1:3)
pond sides, but the inlet points are located shoreward of the entire shallow
settling basin of each pond, which may also help minimize the entrainment of
mineral detritus during irrigation.

Energy Requirement

The operators visit the site to open (morning) and close (afternoon) manually-
operated irrigation valves twice each workday during the 6-month irrigation
season. Each morning they record the daily influent volume at the final col-
lection system lift station, and from there they make the first daily visit to
the site, a round trip site visit of one mile. The second site visit (early
afternoon) is a separate round trip of two miles. The Village pick-up truck
will use around 0.1 gal./mile on these excursions. Approximately one-third
of the site time is devoted to inspection of the ponds.

The annual cost of gasoline involved with irrigation of the wetlands, based on
the above, is:
26 wk x da x 3 miles x 0.1 gal. x $1 x 2= $26.00.
wk da mile gal. 3.
Approximately $20.00 worth of gasoline is involved in mowing the long wetland-
facing berm slopes.

Use of electrical energy to operate the wetlands is indirect. The ponds are
elevated with respect to the wetlands in order that irrigation may be done by
gravity. Extra lift of 22.3 ft (the average difference between the elevation
of the ponds and fields) is involved, and the total lift from the final collection
system lift station to the influent wetwell at the ponds is 84 feet. The energy
consumed at the final lift station in 1978 was 16.225 kwh for which the Village
was charged $0.06 per kwh. A monthly service charge of $5.00 was added to each
billing. The annual electrical energy cost to operate the wetlands is:

(16,225 kwh x $0.06 x 22.3f + (12 x mc, $318.44.
kwh 84 ft� $M.00)

149

In 1978, 28.5 million gallons were irrigated at an average electrical energy
cost of:

$318.44/28.5 MG =$11.17/MG.

The total energy costs including site visits for irrigation are $364 per year -
roughly $1.00 per day or $12.81/MG.

Not uncommonly, the electrical energy costs of seepage wetland operation would
be much lower than at Vermontville. One hypothetical situation involves a pre-4
existing secondary treatment facility from which effluent could be drained by
gravity into a new lower-lying wetland. Another situation would obtain where4
design of new secondary facilities and gravity-fed seepage wetlands need not
include extra collection system lift station capacity to enable gravity oper-
ation of the wetlands.

Labor

Approximately ten man-weeks are invested in the wetland facility during late
spring-early autumn irrigation season by the wastewater treatment staff. No
time is given to the facility in the off-season.

Analytical

Monitoring of the surface overflow from the final wetland field (F4) involves
costs of $260/month for eight months, or approximately $2,000/year. This cost
figure is roughly twice that for a hypothetical seepage wetland system without
a surface overflow but which might be monitored with three ground water wells
on a quarterly schedule.

DELIBERATE DESIGN OF SEEPAGE WETLANDS

Factors which may mandate conscientious planning and design to optimize waste-
water treatment and wildlife habitat, while minimizing construction and O&M
costs and adverse environmental impact, are:

1. Ground water quality regulations (environmental impact).

2. Need for "slow" seepage and spatial variation in water depth with
interspersion to promote variety (wetland habitat development).

3. Need for rapid enough seepage to infiltrate all applied wastewater
without uncontrolled runoff (treatment).

The use of seepage wetlands for wastewater treatment adds soil-filtered waste-
water to the existing ground water. The soils will likely remove phosphorus,
bacteria, suspended solids, and BOD adequately to meet stream water quality
requirements. Nevertheless, state ground water quality regulations often specify4
that disposal of wastewaters shall not degrade a usable aquifer. The regulations

150

may apply even where filtered wastewater meets drinking water quality standards.
Where the use of a potential site would result in degradation of a developable
portion of an aquifer contrary to regulations, then some means of post-seepage
retrieval of the filtered wastewater and approved final discharge must be de-
signed. In Michigan, this condition with respect to upland irrigation has often
involved a choice between recovery of irrigated wastewater with purge wells
followed by discharge to a stream, versus selection of a different site located
on the nearest developable property to an influent stream. In Michigan, a
nearby stream or its bordering lowland would almost always be the natural line
of discharge for the most shallow ground water zone within an indefinite dis-
tance landward of the floodplain. A seepage wetland site at or near such a
stream floodplain boundary would be acceptable without the need for post-seepage
treatment. The availability of such a location would offer clear O&M advantages
compared to pumping irrigated water out of the ground prior to discharge to a
stream.

Design and construction of seepage wetlands would be more straightforward if
the requirements for physical control of wastewater were the same as in con-
ventional upland irrigation on well-drained soils. The basic upland requirements
include soils which are adequately open to accept the design amount of waste-
water, and depth to the unconfined ground water adequate to prevent excessive
rise in the water table due to irrigation. The range of allowable application
rates is limited on the low side, but almost never on the highside. With
seepage wetlands, however, the rate of application is usually limited on both
the high and low ends because of the need to establish wetland vegetation and
to prevent uncontrolled runoff, respectively. The low limit insures standing
water for many hours to several days at a time, while the high limit prevents
surface water from rising to the level of uncontrolled overflow.

A seepage wetland could be constructed and operated to follow one of several
schemes. Assume humid-temperate conditions and low-relief wetland contouring
to provide water depth interspersion over a depth range ofsay, +0.3 ft (drained,
but poorly) to -3 ft (well submerged).

On a site with natural conditions of uniformly restrictive soils, the design
weekly increment of wastewater applied intermittently during the week should
be planned to seep away in a little under a week's time to avoid overflow
during rainy periods. There would be some time-variation in water depth on a
weekly cycle, typically two inches or ma~re. The relative variation would be
greater in the shallower water areas than in the deeper water environments.
More uniform water depths could be maintained, if desired, by applying water
continuously at a constant rate, equal to the rate of seepage, with inter-
ruption of irrigation during significant rainfall. With the latter approach,
the length of the irrigation season would probably be little different from
that ensuing with intermittent irrigation.

A number of unified soil classes could be acceptable for seepage wetland settings
(Figure 4). Siltiness is a general indication of suitability. Most soils within
the five more suitable classes -- GM, SM, SC, OL, and MH are prevalently or
significantly silty. Mixtures of the finer sand grades and clayey sands within

FIGURE 4

UNIFIED SOIL CLASSES
WITH HYDRAULIC CONDUCTIVITY

IO-3 to 10-6 cm/sec

CLASS TYPICAL NAMES WORKABILITY
SILTY GRAVELS
GM Ea GOOD
GRAVEL- SAND- SILT
SILTY SANDS
SM a' FAIR
SAND SILT MIXTURES
INORGANIC SILTS
VERY FINE SANDS
S C SILTY OR CLAYEY FINE SANDS FAIR
CLAYEY SILTS (LOW PLASTICITY)

10-4 to 10-6 cm/sec
ORGANIC SILTS
O L ORGANIC SILTY CLAYS POOR
( LOW PLASTICITY)
INORGANIC SILTS
MICACEOUS OR DIATOMACEOUS- POOR
M H IFINE SANDY OR SILTY SOILS
ELASTIC SILTS

MOST DESIRABLE RANGE 10-4-10'5 cm/sec

152

the named soil classes may also be suitable. In their natural condition, the
forenamed classes could be too permeable for wetland vegetation to self-establish.
For example, design for four inches per week application would call for hydraulic
conductivity of around 10-4.8 cm/sec, which is close to the lower limit of
infiltration indicated for the first three classes named. But the openness of
the soils can be reduced during construction through compaction. Because
compaction may decrease the soil 's water intake rating by an order of magnitude
or more, care in achieving the right degree of compaction is called for. The
GM, SM, and SC soils may be readily compactible (fair to good workability). The
OL and MH materials are usually difficult to work and to compact, and the OL soils
may support only light equipment.

An alternative approach to construction and operation is selective compaction
to achieve a suitable surface for direct application of wastewater (Figure 5) and
primary wetland establishment. An uncompacted perimeter area contiguous with the
compacted surface would receive and seep away any overflow from the compacted
zone. The entire area would be enclosed with low berms to prevent uncontrolled
runoff. In soils which cannot be adequately tightened by compaction, closure
could be achieved with bentonite or clay while preserving an open-soil perimeter
for overflow control. This procedure might be more expensive than selective
compaction, but with it the seepage wetland solution is technically applicable
in highly permeable sandy terrane as well as in silty soils. The non-uniform
soil infiltration approach to seepage wetland construction would allow uniform water
* ~depth to be niaintained, even with considerable latitude in application fre-
quency, while preventing uncontrolled runoff.

* ~Where soil manipulation is employed, the affected soil depth will usually be one
foot or less. To maintain the integrity of the thin "seal ," young willow and
any other trees should be cut down at the whip stage, because if these trees
were to fall over at maturity a substantial part of the seal would be destroyed
as roots tear free of the ground. Annual hand cutting during late winter or
early spring dormancy should be a low cost routine.

CAPITAL AND LAND COSTS

Seepage Wetlands vs Upland Spray Irrigation

Capital costs for seepage wetlands are calculated and compared to costs for
spray irrigation. The land required for direct use is assumed to be the same
for both methods at application rate of 4 in. per week. Therefore, the purchase
costs of land for direct application, land clearing costs, costs for access
roadways, and costs for monitoring wells are considered to be the same for both
methods. Costs related to transmission pipeline from secondary treatment faci-
lities including installation and pumping station are also considered to be the
same for both methods. Square shape application areas and square total areas
including isolation land are assumed.

The cost differences between the two methods arise in requirements for
chlorination, isolation land, site grading, electrical power and irrigation

153

01 :

4 w ; : i:t 0 d t; t : i z�) i W 0 00 0 : .0 0 : S0 00 S 0 0 :

FIGURE 5. RENDERING OF A SPEIEL
Ii | t|
X X X # | g | i ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i,

FIGURE 5. RENDERING OF A SEEPAGE WETLAND

Table 1. Unique Unit Costs Assumed for Spray Irrigation and Seepage
Wetland Systems.

ITEM January 19771 January 19792

GENERAL LAND $1,000/ac. $1,154/ac.
I
R CHLORINATION
SR ACHLORITION $25,000 $28,838
S R FACILITIES
P I
R G POWER $10,000 $11,535
A A FACILITIES
Y T
I SPRAY
I EQUIPMENT $3,000/ac $3,460/ac.
0 EQUIPMENT
N

S W SITE $4,000/ac.
E E GRADING
E T
P L GATED
A A IRRIGATION $21/ft $24.22/ft
G N PIPE
ED

1 Michigan approximate cost figures (reference 10).
2 Update of costs to January, 1979 (reference 11).

structures. Spray irrigation is assumed to require pre-chlorination and an
owned isolation perimeter 800 ft deep around the application site, as well
as irrigation structures and an electrical power facility. No site grading
is assumed for spray irrigation. Seepage wetlands are assumed to require
200 ft of owned isolation land, site grading (irregular leveling and con-
struction of low berms), and irrigation structures. Chlorination and an
electrical power facility are assumed not to be needed for the seepage wet-
land areas. The "no power facility" assumption is conditional upon effective
gravity flow between the secondary treatment site and the wetland. An irri-
gation structure in the form of gated piping and support fixtures is assumed
for seepage wetlands. The length of the structure is assumed equal to one
edgelength (square) of the wetland area.

The assumed unit costs for unique components of the two methods are given in
the included Table 1. The costs are based on general cost figures for Michigan
as of January, 1977 (10) and updated to January, 1979 (11). The present wet-
land irrigation structure costs may be nearer the tabulated 1977 value of
$21.00 per foot than the $24.22 figure (Table 1), because the Houghton Lake
wetland irrigation structurecosts $21.00 per foot in 1979 dollars.

155

Table 2. Assumed General Conditions, Unique Capital Costs for Seepage
Wetlands and Spray Irrigation, and Overall Cost Differences

G CONDITIONS IRRIGATION 4-IN./WEEK, 6 MO/YR
E POPULATION170 gal,./ 444 1,000 1,778 2,778 4,000 5,444 7,111
AT THESE Icap-da
UNITFLOWS cap-dal. 311 700 1,245 1,945 2,800 3,811 4,978
E FLOWS Icap-da
R TOTAL DAILY 0.031 0.07 0.124 0.194 0.28 0.38 0.50
FLOWS (MGD)
TREATMENT 4 9 16 25 36 49 64
L ACREAGE
I ADDITIONAL
I ADDITIONAL CEG78 90 101 113 124 136 148
R ISOLATION ACREAGE
S
R ADDITIONAL ISOLA- 90,012 103,860 116,554 130,402 143,096 156,944 170,792
P TION LAND COSTS (C)
R SPRAY FACILITIES
R SPRAY FACILITIES 13,840 31,140 55,360 86,500 124,560 159,540 221,440

A CHLORINATION
Y A CHLORINATION 28,838 28,838 28,838 28,838 28,838 28,838 28,838
TCOSTS
I cPOWER FACILITY 11,535 11,535 11,535 11,535 11,535 11,535 11,535
COSTS

SUBTOTAL SPRAY 144,225 175,373 212,287 257,275 308,029 366,857 432,605
N COSTS (A)

S W GATED PIPE AND 10,100 15,165 20,200 25,275 30,330 35,385 40,400
E E FIXTURES
E T
P L SITE GRADING 16,000 36,000 64,000 100,000 144,000 196,000 256,000
A A COSTS
G N SUBTOTAL WETLANDB) 26,100 51,165 84,200 125,275 174,300 231,385 296,400
E 0 COSTS (B)

C ~ A - B 118,125 124,208 128,087 132,000 133,729 135,472 136,205
0 F ASMN OE
S F ..ASSUMING LOWER 73,119 72,278 69,810 66,799 62,181 57,000 50,809
R LAND COST:$577/ac
T E
;...ALSO ASSUMING 79,119 85,778 93,810 104,299 116,181 130,500 146,809
E LOWER GRADING
S COST=$2,500/ac
COST DIFFERENCE RANGE 70,000- 70,000- 70,000- 65,000- 60,000- 55,000- 50,000-
($) 120,000 125,000 130,000 135,000 135,000 140,000 150,000

Table 2 gives a detailed tabulation of unique costs for spray irrigation and
seepage wetlands, subtotals for each method, and overall cost differences for
daily wastewater flows in the range 0.031 to 0.5 MGD and the corresponding
application areas of up to 64 acres.

With the assumptions of Table 1, the costs of spray irrigation exceed the seep-
age wetland system costs by nearly constant amounts within the given range of
flows, averaging $129,689 with a standard deviation of $6,632 for the entire
range of flows. With a different assumption that land might be bought for

156

one-half the earlier assumed cost, or $577 per acre, spray irrigation systems
would cost $73,119 more at 0.031 MGD, and $50,809 more at 0.5 MGD. Add to this
assumption the further assumption of site grading costs at $2,500 per acre
instead of $4,000 per acre, and the spray method costs exceed those for the
wetland method by $79,119 at 0.031 MGD and $146,809 at 0.5 MGD. Combining
the several assumptions, the approximate range of cost differences under different
assumed conditions would be $70,000 to $120,000 at 0.031 MGD and $50,000 to
$150,000 at 0.5 MGD.

Overall Capital Costs

Capital costs for spray irrigation systems were calculated in great detail for
ten Michigan communities in 1977 (10). All spray irrigation sites were located
within three pipeline miles of secondary facilities. The range of wastewater
flows among the ten communities is 0.07 to 0.24 MGD. The assumed rate of
application of wastewater in the earlier study was 2 in./wk. Adjustment of
these earlier calculations with allowance for the new assumed rate of application
of 4 in./wk and for increases in costs over the two intervening years yields an
expression, C = 2,600 F + 145, where C is the capital-plus-land cost in 1,000's
of dollars and F is wastewater influent flow in MGD. This expression must be
further adjusted upward by 15.4% to reflect changes in construction costs (11)
and assumes similar changes in land costs between January, 1977 and January, 1979.
The new cost versus flow expression for spray irrigation systems is C = 3,000 F
+ 167.3. In Figure 6, a spray irrigation cost curve based on this equation,
and the seepage wetland costs and cost savings listed as A-B costs in Table 2,
are plotted. Seepage wetland capital cost savings are greater than 26% where
flows are less than 0.1 MGD, 14% at 0.25 MGD flows and 8% at 0.5 MGD flows.

DISCLAIMER

The Vermontville studies are supported through a grant from the National Science
Foundation to Williams & Works. Any opinions, findings, and conclusions or
recommendations expressed in this paper are those of the authors and do not
necessarily reflect the views of the National Science Foundation.

157

BASIS : 41N/WK, 26 WK/YR
LAND $1153/AC

1.5- / /

z A/1'SEEPAGE
� 1 /- WETLAND

. y //SEEPAGE
WETLAND
.Cj// SAVINGS
0 226% 14% 8%

O .1 .2 .3 4 .5
FLOWS (MGD)

FIGURE 6. CAPITAL COST COMPARISON

158

PART II: HOUGHTON LAKE

BACKGROUND

Houghton Lake in Roscommon County (Figure 7) is Michigan's largest inland
lake, and is a vacation haven for city dwellers from Michigan and surrounding
states. The Houghton Lake area's Tni-Township treatment plant (Figure 8)
serves a seasonally variable population. The winter and off-season population
is approximately 5,300, and the peak summer season population is around 13,500.
These figures are expected to increase to 8,000 and 16,900 by 1988, and to
10,300 and 22,400 by 1998.

Construction of "conventional" treatment facilities for stabilization and land
treatment of wastewater to serve the H-oughton Lake community through 1978 was
completed in 1975. Two aeration ponds of 5.2 acres each and 10 ft working
depth are followed by three holding ponds of 29.5 acres total area and 8.5 ft
working depth. The holding ponds are designed to discharge into eight seepage
beds of 5 acres, and into five flood irrigation fields totaling 85 acres.
There is holding pond storage capacity for 140 million gallons over the six
winter months, and the seepage and flood irrigation areas can treat 208 million
gallons annually--the 1978 design flow on an average 81 gal./cap.-da basis.

The need for collection and treatment of wastewater from around Houghton Lake
was realized in the 1960's as residential and commercial septic system fail-
ures threatened the economic well-being of the area. Even with increasing
numbers of summer lake dwellers and year around cottage homes--major con-
tributors to the problem--the area's financial base continued to be modest.
How to treat wastewater affordably was a question very much on everyone's
mind in 1968. In this rural setting, stabilization ponds were the best choice
among secondary treatment alternatives, we thought. Then in 1968, the Lake
Michigan Enforcement Conference of the Federal Water Pollution Control Admin-
istration (an EPA precursor) established that 80% removal of phosphorus would
be required before discharging into streams tributary to Lake Michigan.

At the time, there were no thoroughly tested alternatives to expensive mechan-
ical-chemical-biological phosphorus removal systems. The Pennsylvania State
University studies of the living filter system (12), however, were attracting
much interest. The Michigan Department of Natural Resources (DNR) was cogni-
zant of the new burden that the phosphorus rule placed on rural communities.
Thus, in 1970 when we recommended flood irrigation facilities, we had the
needed support of the state even though very few municipal irrigation facilities
were yet in operation in Michigan.

By 1971, the Houghton Lake community had a conceived treatment system designed
for 600,000 gal. per day that would serve them until 1978. And it only remained

159

OSCOMMON,
/HCOUNTYHOUG
LAKE

ROSCOMMON
TOWNSHIP

FIGURE 7. LOCATION OF HOUGHTON LAKE, MICHIGAN

160

HOUGHTON13

LAKE

e-EXtI ING TREATM
TE

ROSCOMIr ON TWP.

FIGURE 8. LOCATION OF TRI-TOWNSHIP WASTEWATER
TREATMENT SITE, NOT INCLUDING WETLANDS

161

to locate land for expansion to 1998 design capacity. But the cost of upland
property was increasing, and although the option to purchase additional upland
remained open until the spring of 1977, efforts to develop a more attractive
alternative were initiated in 1971 and continued for seven years.

Houghton Lake is in the very poorly drained headwaters of the Muskegon River,
and there are thousands of acres of swamps within a few miles of the service
area population. It occurred to us that swamp lands south or west of the
treatment area might be able to take the pond effluent and give it tertiary
treatment. The lands were largely owned by the state and we thought they might
be usable at little cost. Early in 1971 we met with the division chiefs of
the Michigan DNR to discuss the idea. There was some discussion of the swamps
being infertile and unproductive, and perhaps wastewater nutrients would be
just the thing to bring them to productive life. The DNR was interested but
there were many questions and few reliable answers about the idea. There was,
of course, little published information or experience at the time to support
any far reaching decisions. But the DNR was interested enough to request that
researchers at the University of Michigan, John and Bob Kadlec, develop an
environmental feasibility study and report. Through the efforts of these
researchers, the National Science Foundation came in to assist with virtually
complete funding of the wetland studies beginning in mid-1972.

Between 1972 and 1977, the researchers identified the baseline characteristics
of a wetland tract known as the Porter Ranch peatland, and tested the peatland
with up to 100,000 gal./da quantities of pond stabilized wastewater. The peat
soil substrate, which is up to 4 ft and greater in thickness, is fragile. Dur-
ing the experimental period, the research project team took special care to
minimize marking the wetland with evidence of their ingress and study activi-
ties. This care was rewarded in there being only one or two faint path marks
which persist today. The evident sensitivity of the peatland pointed to the
need for design which would allow environmentally compatible irrigation pipe-
line construction and operation.

TREATMENT EXPANSION ALTERNATIVES

The facilities plan (13) compares capital and O&M costs for the wetland treat-
ment system (A), physical-chemical-biological treatment (B) and expansion of
the existing upland irrigation treatment system (C). Table 3 below is a tabu-
lation of the January, 1976 costs estimated for the three alternatives, A, B,
and C.

Table 3. Capital Cost Comparison for Alternative Treatment Methods

A B C
Capital ($1,000's)

Construction 591 1,730 1,108
Miscellaneous 158 370 262
Land 0 0 184
I. Total Capital 749 2,100 1,554
II. O&M (20 years) 320.5 901.3 316.5
III. Salvage Value (20 years) 32.5 54.3 127.5
Net Present Worth (1+11-III) 1,037 2,947 1,743

162

Savings of $805,000 in capital costs were projected for the wetland alterna-
tive compared to expanding the existing upland irrigation system. Updating
to January, 1978, when construction contracts were awarded, involved an in-
crease in capital costs of approximately 16% (11), or projected capital
savings of approximately $934,000.

DESIGN

The Wetland Irrigation System

The wetland irrigation pipeline (Figures 9 and 10) is located approximately
one-half mile out into the wetland, in the downgradient direction (southwest)
of surface water movement. It was anticipated that backflow or backup of the
slowly-moving wetland surface water would occur during irrigation, and the
resulting flow, water level and treatment effects could best be documented
by allowing abundant upgradient distance and area between the pipeline and
the northeast edge of the wetland.

Beneath the peat floor lie several tens of feet of glacial lake bed clay.
Although the peat would be of no use as a bed for a conventional pipeline
arrangement, the underlying clay would present no foundation problems. Several
experiments, including flotation and pilings as support mechanisms, resulted
in the adopted design.

Wastewater is carried into the wetland through a 2500 ft-long 12-in. aluminum
header pipeline. This pipeline makes a tee connection at the center of a
3,200 ft-long gated aluminum irrigation pipeline. Each arm of the irrigation
pipeline is stepped down in size (Figures 10 and 11) from the tee connection to
outer end with 400 ft each of 12-in., 10-in., 8-in., and 6-in. piping. Waste-
water flow into each irrigation arm can be controlled separately by 12-in.
aluminum butterfly valves (Figure 11). Irrigation gates are positioned at
15-ft intervals.

The transmission and irrigation pipelines are supported above the wetland
surface on a wooden walkway. The walkway in turn is supported above the wet-
land surface on a frame which is anchored in the clay substrate.

The walkway consists of 2-in. x 6-in. x 32-in. hardwood planks nailed on 8-in.
centers to 2-in. x 8-in. rails. The support frame for the walkway is made up
of separate units, each consisting of a pair of 2-in. ID pipe poles anchored
in the clay, and joined together by 2-in. x 6-in. x 48-in. hardwood planks.
The planks are fastened to the pipe poles "edge-up," with two U-bolts per pole.
The frame units are spaced 10 ft apart (Figure 12).

The pipelines are supported on one edge of the walkway directly over a 2-in.
x 8-in. rail. The pipelines are strapped to the rail with aluminum straps on
8 ft centers, and are supported laterally by contact with the 2-in. pile pipes
(Figure 12).

163

NELLSVILLE

I//

SEC. 5 SEC.4

WETLAND- r , _
/ UPLAND o
MARGIN J
J 0

PROPOSED 12" FORCE
~\ 9~t,. -$7 LINE

l' ! EXISTING
PROPOSED GATED REATE

SEC.8 -- X S

~~ -PROPOSED
/ -v at'DECHLORINATION
POND

4S~~ ~SEC. 9 /

FIGURE 9. LOCATION OF OLD ("EXISTING") AND NEW
("PROPOSED") TREATMENT FACILITIES

164

S�b. 3O+00 Aproxnat.e
Of A.-s-

165
P~''0
,+\Z �iP~ ~~ ~~ PO~~~P/
\C o~~~~~~~~~~~~~ SjO~~~~~~~~~~~~~CI~~~~~~~~I1~~~~~~~
V~~d rfG qqg'
FIGU~~~~~~~RE t0. SCEAICLYU O ELNDHAE

AN IRIATONEPELNS OGTNLK

165c'\"iJc~

I, IlJ

r-1-Rt~~~-----I-I -___r _________
S-B L3ZI~~ ~ ~~~~~~IZ 8-*

-__- ~~~~11 y H1D/ 7<' ii _
tI Ill I

liii II

~~~~~~~~~~~Jill
iiHIT

,' Ic I I /I
In IJII
II I ii
.......... -----_::.--*.......

n I III I
-I -IT' . .... . I

II~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I
---l I

.. I I I1 _ j -
--z :~~~~~~~~---:-:----4:' ...._-.......
IS .. .. I'II

5-9, _ It.

FIGURE 11. TEE AREA OF WETLAND IRRIGATION SYSTEM: HOUGHTON LAKE
JI ll

~, ~~ ~ ~ ~ ~ ~ ~ ~~~~~illi-: _'

Ilil 1

FIGURE 11. TEE AREA OF WETLAND IRRGATION SYSTEM: HOUGHTON LAKE

-t ~--2" 4 /k/I~S I~, 2wg'

~~~~~~~~HIIV-

VI L )i 4- yeS/ 11) VSU

~~~~~SECTeA'nmnw .p.IO lr- S 8
FI GR 12. TIL O
STTHT

$~~~~~ndc6x or"

S~ECT/ON/ "C-c"

FIGURE 12. DETAIL OF WOODEN WALKWAY AND PIPELINE SUPPORT
STRUCTURES IN THE WETLAND: HOUGHTON LAKE.

The header and irrigation pipelines, fittings, and valves are welded aluminum
alloy with lock-ring couplers and gaskets. The irrigation slide gates are of
high strength nylon and delrin. The gates slide over rectangular orifices cut
in the pipe, in side-to-side fashion, from fully open to fully closed.

Other

Construction related to the wetland treatment scheme included modifications
and additional structures at the upland treatment site. Also, the regulatory
authority wanted assurance that neither pathogens nor residual chlorine would
reach the wetland. Hence, the most significant new structure is a dechlor-
ination pond (DP) of 2.6 acres area and 12 ft depth (location shown in Figure
9). In fact, the concern over pathogens which might survive the stabilization
ponds has diminished because fecal coliform standards (200/100 ml) are being
met without chlorination. Chlorination has not been done, and the dechlori-
nation pond has been used as an intermediate holding pond with two days capa-
city at 2 MGD.

CAPITAL COSTS

The capital costs include materials and labor for modifying the final holding
pond, construction of the dechlorination pond, forceline to the wetland,
irrigation header, irrigation lateral, wetland support structures, and moni-
toring and analytical equipment. The capital costs itemized below are com-
plete except for engineering*, and except for research funds extended by the
National Science Foundation for the initial proof-of-concept period.

Holding Pond Modification

Auxiliary pump structure = $ 6,500
New and modified control structures : 4,400
Leveling 900
Transfer pipe (to DP),
20-in., 1,605 ft @ $16.69 = 26,787

Subtotal $38,587 $38,587

Dechlorination Pond

Site preparation and excavation $84,103
Transfer pump structure : 57,907
Metering and control structures : 11,200

Subtotal $153,210 $153,210

*Design, construction inspection, hydrogeological studies, soils studies,
O&M manual, startup assistance, etc.

168

Pond-Wetland Transmission

Forceline, 12-in., 5,589 ft
@ $14.00, plus bends $80,646
Air-release and cleanout manholes = 3,000

Subtotal $83,646 $83,646

Irrigation Header System

Header pipe, 12-in., 2,500 ft
@ $7.50 $18,750
Support Structure, 2,500 ft
@ $12.97 32,425

Subtotal $51,175 $51,175

Irrigation Lateral System

Gated pipe (12-in., 10-in......
6-in.) $18,864
Support structure
3,200 ft @ $12.97 41,504
Valves, bends, reducers,
end caps, tee 1,224

Subtotal $61,592 $61,592

Monitoring

Wells = $ 1,830
Analytical equipment : 7,890

Subtotal $ 9,720 $ 9,720
Total Capital Cost = $397,930
$400,000

Capital costs were offset by an 80% construction grant from the USEPA through
the 201 facilities planning program. The design and award of Step 3 funds
occurred ahead of the Clean Water Act of 1977 (14). At present the Houghton
Lake Sewer Authority is applying to the state and federal construction granting
agencies to secure retroactive alternative and innovative status for the wet-
land irrigation facility.

169

OPERATION AND MAINTENANCE COSTS

Wastewater Composition

Raw wastewater contains approximately 80-100 mg/l BOD, 60-80 mg/i suspended
solids, and chloride of 100-110 mg/l. The wastewater is comparatively weak,
probably because of long sewer lines. Phosphorus and the nitrogens are
typical of normal domestic wastewaters. Wastewater applied to the wetland
has COD of 12 to 27 mg/i, total phosphorus of 4 to 5 mg/l, total dissolved
phosphorus of around 2 mg/l, nitrate-N of 1.2 mg/i, ammonia-N of 0-3.5 mg/i,
fecal coliform of 150/100 ml and fecal streptococcus of 10/100 ml.

Electrical Energy for Wetland Irrigation Pumping

Energy consumption for irrigating the wetland includes that consumed in
pumping from the dechlorination pond (DP) to the wetland.

In 1979, 101 MG were applied to the wetland between June 18 and August 20,
with one week of shutdown for forcemain repairs. The average rate of
irrigation in this period was 2 MGD, with water being applied at rates up
to 3 MGD. Irrigation was often done round the clock.

Layne-single stage vertical turbine pumps (Model 14THC) operate between the
DP and the wetland, with roughly 82% efficiency at 1600 rpm and 40 ft TDH.

The 1979 cost of pumping to the wetlands from the DP is, therefore, approximately:

101x106 gal. x 1 Ift x62.4 lb 1 hp-sec 1 hr 0.746 KW
7.49 gal. ft3 550 ft-lb 3,600 sec hp

x4OftTD~$0O04 1 1
x 40 ft TDH x ~X$72.75
KWHx p.e.(82%) x m.e. $727.75

The calculated cost per million gallons is $7.21/MG.

Other O&M for Wetland Irrigation

Other O&M costs include repair, inspection, environmental monitoring and
equipment. For the first seven months of 1979 the itemized costs are:

Irrigation pump (DP to wetland) and valve repair $ 191.00
Semi-weekly inspection of the wetland system 400.00
Ecological monitoring (graduate student) and 5,800.00
lab analyses of environmental waters
Laboratory equipment purchased 1,200.00

170

For the remaining months of 1979, assume repair and inspection costs to
continue as shown, ecological monitoring to continue as shown through October
and no new lab equipment. The total anticipated O&M for wetland irrigation
in 1979, including irrigation energy, is therefore,

$728 + 1 (191 + 400) + 1](5,800) + $1,200 = $11,227 or 111/MG.

Environmental monitoring by the University of Michigan wetlands ecosystem
research group continues with National Science Foundation support. This
support is in addition to the $11,227 figure given above.

Overall Operating Costs

The wetland system O&M is approximately 20% of the total treatment O&M
budget for the Tri-Township system. Total 1978 O&M costs for the complete
Tri-Township treatment facility include maintenance and clerical salaries
($28,500 including benefits), electrical energy to pump wastewater ($13,409
including the final collection system lift station), insurance ($8,362),
HVAC ($3,724), repair and replacement parts ($1,500), gasoline ($1,000),
laboratory equipment ($654), postage and telephone ($500), custodial sup-
plies ($370), and treatment personnel education ($150). The total 1978
figure is $58,169. Upward adjustment by 7.2% to the 1979 timeframe (11)
yields $62,357 for current annual O&M costs.

The wastewater treated and disposed in 1979 was 101 MG (wetland) and 29 MG
(seepage beds), for a total of 130 MG. The unit O&M costs for the entire
Tri-Township treatment system arearound $300/MG, because the flow to the
treatment site is 198.5 MG/year with 68.5 MG being pond leakage or meter
disagreement.

Because so many of this system's costs are fixed costs unrelated to flow,
we calculate (without inflation) that, at design flow, the total O&M cost
(including both collection and AWT) will fall to around $200/MG.

The design flows for the year 1998 are:

Annual average of 1.1 MGD
Eight-day peak flow of 1.85 MGD

The residential sewage service charge is $75/year, regardless of days of
occupancy. Front foot assessments for local sewer construction ranged from
$10 to $13/front foot.

Williams & Works' operation and management staff screened, hired and trained
all permanent operating personnel, because the operating authority (Houghton
Lake Sewer Authority) was a newly created public agency.

171

REFERENCES

1. Williams & Works, Inc. (1979). Reuse of Municipal Wastewater by
Volunteer Fresh-Water Wetlands. Interim report to the National
Science Foundation: ENV-20273 (April).

2. Bevis, Frederick B. (1979) "Ecological Consideration in the Manage-
ment of Wastewater - Engendered Volunteer Wetlands," in Conference
Abstracts: Wetland Utilization for Management of Community Waste-
water, Higgins Lake, Michigan, July 10-12, 1979. (Tables available
from the author).

3. Sutherland, J. (1979) "The Vermontville, Michigan, Wastewater-Grown
Volunteer Seepage Wetlands: Water Quality and Engineering Implica-
tions," in Conference Abstracts: Wetland Utilization for Management
of Community Wastewater, Higgins Lake, Michigan, July 10-12, 1979.

4. Jones, R. C. (1979) "Design and Construction Aspects of the Houghton
Lake Wetland Irrigation Project," in Conference Abstracts: Wetland
Utilization for Management of Community Wastewater, Higgins Lake,
Michigan, July 10-12, 1979.

5. Williams, T.C. (1979) "The History and Development of the Houghton
Lake Wetland-Wastewater Treatment Project,"in Conference Abstracts:
Wetland Utilization for Management of Community Wastewater, Higgins
Lake, Michigan, July 10-12, 1979.

6. Sloey, W. F., Spangler, F.L. and Fetter, C.W.,Jr. (1978) "Management
of Freshwater Wetlands for Nutrient Assimilation," in Freshwater
Wetlands (Ecological Processes and Management Potential) (R.E. Good,
D. F. Whigham and R. L. Simpson, editors). Academic Press, pp 321-340.

7. Lee, G.F., E. Bentley, and R. Amundson (1969) "Effect of Marshes on
Water Quality (mimeo)." Water Chemistry Laboratory. Madison, Wisconsin.

8. Bender, M.E. and D.L. Correll (1974) The Use of Wetlands as Tertiary
Treatment Systems. NSF-RA-E-74-033. NTIS PB-241002 (June).

9. Fritz, W.R. and S.C. Helle (1977) Tertiary Treatment of Wastewater
Using Cypress Wetlands. Preliminary Report: NSF-ENV-76-23276
(November).

10. Sutherland, J. (1977) Investigation of the Feasibility of Tertiary
Treatment of Municipal Wastewater Stabilization Pond Effluent Using
River Wetlands in Michigan. Final Report to the National Science
Foundation (NSF ENV 76-20812 and NTIS PB 275-283).

172

REFERENCES (Cont.)

11. Engineering News Record Construction cost indexes.

12. Parizek, R.R. et al, (1967), "Waste Water Renovation and Conservation,"
The Pennsylvania State University Studies No. 23. 71 pp.

13. Williams & Works (1976), Houghton Lake Area Facilities Plan, Step I,
Federal Project C-262768 (April).

14. Federal Register, Vol. 43, No. 188 (43FR 44022), September 27, 1978:
EPA Municipal Wastewater Treatment Works Construction Grants Program.
Rules and Regulations.

15. Williams, T.C. and Jeffrey C. Sutherland (1979) "Houghton Lake, Michigan,
Peat Wetland Tertiary Treatment System," Water Pollution Control Federa-
tion Conference (Session 44), Houston (October).

173

Aquatic Plant Processes
Session

J-.

Photo of a large pond in San Juan, Texas covered by water
hyacinths to help improve water quality. Inserts depict water
hyacinths being harvested from the Disneyworld water hyacinths
testing facility at Lake Buena Vista, Florida and a duckweed
covered treatment pond near North Biloxi, Mississippi.

AQUATIC PLANT PROCESSES: SESSION SUMMARY

Presentations in this session covered wastewater treatment utilizing vas-
cular aquatic plants with water hyacinth (Eichhornia crassipes) being the
predominate plant discussed. The potential of more cold tolerant plants
such as duckweed for treating domestic wastewater was briefly discussed.

Results of these studies clearly demonstrate the potential of higher plants
in both domestic and industrial wastewater treatment. Wastewater lagoons
are the most popular and inexpensive method of treating domestic wastewater
in small communities. Data on upgrading sewage lagoons in Mississippi and
Texas presented during the seminar demonstrated the potential for using
this technology for improving the performance of lagoons located in warmer
regions of the United States. Potential problems associated with using
water hyacinth to upgrade sewage lagoons were identified along with sug-
gested solutions.

When plant coverage is complete, single cell lagoons with BODS loading
rates in excess of 40 kg/ha/day without aeration are subject to producing
odors,, especially at night when the plants are not photosynthesizing. Multi-
celled lagoons with surface aerators in the raw sewage cell and single cell
lagoons with maximum BOD5 loading rates of 30 kg/ha/day are the best candi-
dates for upgrading these lagoons using water hyacinth or duckweed.

Data on the use of water hyacinth for tertiary treatment in Florida was
preseifted. The data suggest that all parameters for tertiary treatment
with the possible exception of phosphorus can be met in south Florida
using approximately one acre of water hyacinth per 379 m3/day of wastewater
effluent from an activated sludge plant. Because the ratio of NrP in water
hyacinth plant tissue is approximately 6:1 and the ratio in wastewater
approximately 3:1, nitrogen is depleted first and becomes a limiting factor
before the phosphorus is reduced below 1 mg/I.

Engineering data was also given for designing optimal water hyacinth and
duckweed sewage treatment systems to achieve secondary and possibly tertiary
treatment quality in small communities.

B. C. Wolv'erton, Ph.D.
4/28180

177.

ENGINEERING DESIgN DATA FOR SMALL VASCULAR AQUATIC
PLANT WASTEWATER TREATMENT SYSTEMS

B. C. Wolverton, National Space Technology Laboratories, ERL, NASA,
NSTL Station, Mississippi 39529

A general background of the research findings of the National Aero-
nautics and Space Administration's Vascular Aquatic Plant Program us.Lg
higher plants such as the water hyacinth (Eichhornia crassipes) and duck-
weed (Lemna sp. and SpirodeZa sp.) to treat domestic wastewater is pre-
sented. New data on a small two cell lagoon system using only duckweed
is included. Further laboratory experiments were conducted to correlate
BOD5 removal with known wet masses of water hyacinths. The data from
these experiments with domestic wastewater indicates that an average
total BOD5 removal rate of 4.0 mg BOD5/gram WW (wet weight) could be
achieved with a seven day retention time. When a phenol solution is sub-
stituted for the wastewater, the average total BOD5 removal is 3.5 mg
BOD5/gram WW (wet weight) in seven days. This data along with the re-
sults of the previous field experiments is used to develop design crite-
ria for small domestic wastewater treatment systems servicing a maximum
of 3,000 people. The criteria for these systems addresses the problems
of BOD5 reduction, total suspended solids reduction, odor control, and
sludge accumulation.

INTRODUCTION

In the United States, wastewater lagoons are the most popular and
inexpensive method of treating domestic wastewater in small communities.
Thousands of these lagoons exist throughout the United States for treat-
ing domestic sewage and various type animal and industrial wastewaters.
Wastewater treatment lagoons vary from single to multiple celled systems.
Some of the earlier sewage lagoons were improperly designed and construc-
ted causing short circuiting, reducing the effective detention time and
contributing to high BOD and suspended solids in the lagoon effluent.
Today sufficient information is available to provide a basis for rational
design and construction of wastewater treatment lagoons. For in depth
information on wastewater treatment lagoons see Gloyna,1 Middlebrooks2
and Oswald. 3,4 Lagoon systems constructed in recent years are usually
effective in BOD reduction; however, excess algae can still cause high
suspended solids in the lagoon effluent during warm, summer months.

179

NASA at the National Space Technology Laboratories (NSTL) has been
using higher plants for five years to upgrade wastewater treatment la-
goons and treat chemical wastewaters.5'6'7 NSTL has also been conducting
studies directed toward using higher plants to recycle waste in future
space stations. The controlled use of higher plants such as water hya-
cinths (Eichhornia crassipes) and duckweeds (SpirodeZa sp., Lemna sp. and
WoZffia sp.) in conjunction with waste stabilization ponds not only in-
creased the BOD removal capacity of these systems, but also reduced the
high total suspended solids normally associated with sewage lagoons.
Higher plants reduce suspended solids in lagoon effluents by reducing al-
gae which make up a large portion of the suspended solids. Nitrogen,
phosphorus, potassium, sulfur, calcium and other minerals can be removed
from domestic sewage by harvesting the plant biomass. This harvested
plant material is also a potential source of energy, fertilizer, feed,
food and other products.
One important question about the design of vascular aquatic plant
waste treatment systems that has not fully been determined or fully
understood yet is the BOD removal rate that can be expected for this type
system. The experiments in this report were designed to address this
unknown and achieve reproducible and quantitative answers to this ques-
tion. Results of these experiments and previous field studies were com-
bined to develop design parameters for energy-efficient waste treatment
systems for small communities using vascular aquatic plants.

BACKGROUND

In addition to upgrading all wastewater treatment systems at NSTL
using water hyacinths and duckweeds, NASA has conducted several field
studies with local communities in South Mississippi directed toward im-
proving their lagoon systems using higher plants. Systems described here
will include two single cell lagoons, one at NSTL and one at Lucedale,
Mississippi, and two multi-cell lagoons at Orange Grove and Cedar Lake
developments at Gulfport and Biloxi, Mississippi, respectively.
The single cell lagoon at NSTL has a surface area of 2 hectares and
an average depth of 1.22 meters. The average flow rate of 475 m3/day
resulted in a detention time of approximately 54 days. The BOD5 loading
rate in this lagoon averages 26 kg/ha/day, which constitutes a relatively
light load. Before water hyacinths were added to this lagoon, the raw
sewage entering at the center of the system averaged 91 mg/i BOD5 and
70 mg/i total suspended solids (TSS) with effluent averages of 17 mg/i
BOD5 and 49 mg/l TSS. Concentrations of BOD5 and TSS during a 14 month
water hyacinth covered study period were: influent BOD5 110 mg/i and TSS
97 mg/I, and effluent BOD5 7.4 mg/i and TSS 10 mg/1.6 Plants harvested
from this lagoon contained 2.73% kjeldahl nitrogen and 0.45% total phos-
phorus (dry plant weight).
A single cell facultative lagoon located at Lucedale, Mississippi
was studied extensively with and without water hyacinth coverage.8 This
lagoon has a surface area of 3.6 hectares (9 acres) and an average depth
of 1.73 meters. Lagoon effluent flow rates during 100% water hyacinth
coverage averaged 935 m3/day. The BOD5 loading rate was 44 kg/hectare/
day. Before water hyacinths were added to this lagoon, the raw sewage
entering averaged 127 mg/l BOD5 and 140 mg/i TSS with effluent averages
of 57 mg/i BOD5 and 77 mg/l TSS. Concentrations of BOD5 and TSS during

180

the study period with complete plant coverage were: influent, 161 mg/i
BOD5 and 125 mg/i TSS; effluent, 23 mg/l BOD5 and 6 mg/i TSS. With com-
plete water hyacinth coverage this lagoon was almost entirely anaerobic
with only traces of dissolved oxygen near the surface in the plant root
zone. This condition produced odors at night when the plants were not
photosynthesizing. The BOD5 loading rate of 44 kg/hectare/day produced
odors at night from this lagoon; whereas, a loading rate of 26 kg/hectare/
day in the NSTL lagoon produced a relatively odor free system when cov-
ered with water hyacinths. Plants harvested from this system contained
3.56% kjeldahl nitrogen and 0.89% total phosphorus (dry plant weight).
A complex lagoon system at Orange Grove, Mississippi was used for
conducting a 12 month study with water hyacinths in effluent from aerated
lagoons.9 This system consisted of two large aerated lagoons followed by
three parallel unaerated lagoons. The flow rate into the water hyacinth
covered lagoon averaged 1000 m3/day. This lagoon had a surface area of
0.28 hectare and an average depth of 1.83 m. The flow rate resulted in
an average detention time of 6.8 days. The BOD5 of the influent enter-
ing this lagoon averaged 50 mg/i with an annual effluent average of 14
mg/I. The total suspended solids entering averaged 49 mg/i with an ef-
fluent average of 15 mg/I. A parallel, control lagoon without water hya-
cinth demonstrated effluent concentrations of 37 mg/l BOD5 and 53 mg/1
TSS. Freezing temperatures occurred during this 12 month study period
killing the tops of the plants, and the decay of this large amount of
biomass elevated the BOD5 and TSS levels in the effluent during the
months of January, February, and March. However, the water hyacinth cov-
ered lagoon still maintained the low effluent BOD5 and TSS averages well
below the permit levels of 30 mg/i each. Because of the 1.83 m (6 ft)
depth, the dissolved oxygen averaged 2.0 mg/i in the effluent but was
increased to 5 mg/i following a 0.91 m (3 ft) drop to a drainage ditch.
Plants harvested from this system contained a 3.74% kjeldahl nitrogen and
0.85% total phosphorus (dry plant weight). Evapotransporation rates can
be expected to reach as high as 40% of the total influent volumes per day
during hot summer months. This characteristic was not considered in the
interpretation of these field studies; therefore, the effluent BOD5 and
TSS concentrations should be up to 40% less during the summer months.
A fourth system which is still being studied is a two cell lagoon
system located at Cedar Lake development in North Biloxi, Mississippi.
This system shown in Figure 1 has been in operation for 9 years. It has
been receiving its present load of approximately 49.2 m3/day (13,000 gal/
day) from 51 homes for 7 years. This system was designed as a conven-
tional, two cell lagoon with aeration in the first cell. The first cell
has a surface area of approximately 0.08 hectare (0.20 acre) and an
average depth of 2.4 m (8 ft). The average flow rate of 49.2 m3/day
results in a detention time of approximately 36 days. The BOD5 loading
in this lagoon is approximately 128 kg/ha/day (114 lb/ac/day). The
second cell has a surface area of 0.07 hectare (0.18 acre) and an aver-
age depth of 1.5 m (5 ft) with a detention time of approximately 22 days.
Four years ago duckweed coverage of the second, unaerated cell occurred
through natural means, and NSTL started monitoring this system in April
1979. Prior to this date monitoring had not been conducted; therefore,
background data without duckweeds is not available at this time. In May
approximately 50% of the duckweed coverage was removed for the first
time in four years. The 5 hp surface aerator in the first cell was re-
duced to operating only at night. From May to December 1979 (see Table 1)

181

*5 HP/FLOATING AERATOR
USED ONLY AT NIGHT

ALGAE- .08 ha surface (.20 acre),
2.4 m deep (8 ft)

COVER .07 ha surface (0.18 acre),
1.5 m deep (5 ft)

ANAEROBIC EFFLUENT
.91 m drop (3 ft)

AEROBIC

Figure 1. Sewage Lagoons Serving Approximately 200 People--Cedar Lake
Development Biloxi, Miss.

182

Table 1. Monthly Average Data of TSS and BOD5 for Duckweed Lagoon System Located
at Cedar Grove Development in Biloxl, Mississippi.

TSS, mg/1 BOD5, mg/'
..
Month, 1979 Aerated Lagoon Duckweed Lagoon Aerated Lagoon Duckweek Lagoon
Influent Effluent* Effluent Influent Effluent* Effluent

May 178 397 10 200 64 20

June 194 176 9 203 67 28

July 420 108 16 138 34 13

August 271 113 8 160 13 10

September 233 132 22 173 20 17

October 173 96 19 171 15 8

November 142 61 11 290 29 10

*Also Influent to Duckweed Lagoon

the raw sewage entering the aerated cell averaged 191 mg/i BOD5 and 230
mg/1 TSS. Average influent and effluent concentrations of BOD5 and TSS
of the second duckweed-covered cell were: influent, 35 mg/1 BOD5; efflu-
ent 15 mg/1 BOD5; influent, 155 mg/i TSS; effluent, 14 mg/1 TSS. The
duckweed coverage on the second cell averaged 2 cm in depth producing an
odor free anaerobic system 24 hours a day. The effluent dissolved oxygen
concentration was 0.5 mg/1 leaving the lagoon, but increased to 5 mg/i
after dropping 0.91 m (3 ft) to a drainage ditch.

REMOVAL OF BIOCHEMICAL OXYGEN DEMANDING (BOD)
SUBSTANCES BY HIGHER PLANTS

From field studies' data where water hyacinths were grown in domes-
tic sewage lagoons, one can readily see that an additional reduction in
BOD is taking place that can be attributed to the plants.6'8 Because of
the nature of most sewage lagoons with their long detention times and
complex microbial make-up, controlled laboratory studies are desirable on
BOD removal rate to obtain more exact quantitative data. Laboratory
studies were conducted at NSTL under wide spectrum growth lights with 14
hour photoperiods in an effort to obtain more exact BOD data. Phenol, an
organic chemical, was also used in these studies to further demonstrate
the ability of water hyacinths to absorb, metabolize and remove BOD in a
similar manner to microorganisms. Domestic wastewater consists of a com-
plex mixture of chemicals including phenol and related organics. The ini-
tial volumes of raw sewage or phenol solutions were varied in order to
vary the depth and surface to volume ratio. Some containers were left
free of water hyacinths as controls to determine the bacterial contribu-
tion to BOD removal. In order to assure the same type of bacteria would
be present in the controls that were associated with the water hyacinth
roots, the plant roots were first dipped in all control solutions for
bacterial seeding. Total bacterial counts and 5-day biochemical oxygen
demands (BOD5) were analyzed according to Standard Methods.10
Results of these experiments are shown in Tables 2-4. This data in-
dicates that the water hyacinth alone can be expected to reduce BOD5 of
domestic sewage by an average of 1.5 mg BOD5 per gram of plant mass (wet
weight) with liquid detention times of 6 to 7 days. Water hyacinths and
microorganisms together can be expected to remove an average of 4.0 mg
BOD5/gram plant mass (WW) with the same detention times.
The ability of water hyacinths to remove BOD5 produced by other sub-
stances such as phenol is demonstrated in Table 4. This data indicates
that water hyacinths and microorganisms can remove 3.5 mg BOD5/gram plant
mass (WW) from aqueous solutions in 7 days containing 100 mg/1 phenol.
The BOD5 removal due entirely to the water hyacinth was 1.4 mg BOD5/gram
plant mass (WW). These values are consistent with those found with do-
mestic sewage.
These BOD removal rates were achieved with daily growth rates of 3-
4%; whereas, field studies have shown average daily growth rates as high
as 6% when water hyacinths were grown in sewage lagoons in South Missis-
Spi12
sippi.12 The BOD and suspended solids removal rates are not entirely de-
pendent on growth and harvesting rates; whereas the removal of nutrients
such as nitrogen and phosphorus is dependent on these variables. The BOD
removal rate is dependent on root absorption and metabolic functions; the
suspended solids reduction appears to be associated with algae elimina-

184

Table 2. 5-day Biochemical Oxygen Demand (BOD5) and Bacteria Concentrations
in Raw Sewage With and Without (Control) Water Hyacinths.

Fresh mg BOD removed/
ExpeFre sh Total BOD5 mg/l mg BOD5 removed/ g removed/ Bacteria, count/100 ml
Experiment Mass 5 5 g IHS
WHS, g Initial 3rd Day 6th Day 6 days (6 day exposure) Initial 3rd Day 6th Day

1. w/WHs 1,860 60 --- 5 4,070 2. 2 8.0 x 105 --- 3.0 x 104

2. Control 0 60 --- 24 2, 664 --- 8.0 x 105 --- 3.1 x 104
5 4
3. Control 0 60 --- 35 1,850 --- 8.0 x 10 --- 2.3 x 10
4. w/WHs 2,140 180 48 9 12,664 5.9 7.7 x 105 1.0 x 104 1. 0x10

5. w/WHs 2,000 180 36 7 12,802 6. 4 7.7 x 105 6. 5 x 104 5. 0 x 103
cp 5 3. 6x104 1 04
6. Control 0 180 100 65 8,510 --- 7.7 x 10 3.6 x 10 1.4 x 10

Conditions: Mean Atmospheric Temperature: 22�C

Volume of Raw Sewage: 74 1

Depth: 61 cm

Table 3. 5-day Biochemical Oxygen Demand (BOD5) And Bacteria Concentrations
in Raw Sewage With and Without (Control) Water Hyacinths.

Fresh Total BOD_ mg/l mg BOD removed/ mg BOD- removed/ Bacteria, Count/ 100 ml
Experiment Mass O 5 g's
WHS,g Initial 4th Day 7th Day 7 days (7 day exposure) Initial 4th Day 7th Day

1. w/WHs 506 190 36 20 2040 4.0 TNTC 1.0 x 10 38 x 10

2. w/WHs 429 190 40 20 2040 4.7 TNTC 3.0 x 105 231 x 10
3. w/WHs 413 190 38 21 2030 4.8 TNTC 1.0 x 105 208 x 105
4. Control 0 190 170 85 1260 --- TNTC 1.0 x 105 44 x 10

5. w/WHs 376 112 *50 **21 **1090 **2.9 7.0 x 10 *3.3 x 10 **2. 5 x 10
6. w/WHs 412 112 46 18 1130 2.7 7.0 x 106 4.3 x 106 2.7 x 104

7. w/WHs 386 112 42 22 1080 2. 8 7.0 x 106 2.7 x 106 1.2x 105
8. Control 0 112 76 48 768 --- 7.0 x 10 *** TNTC 4.5 x 10

9. Control 0 112 69 60 624 --- 7.0 x 106 3.1 x 106 3.1 x 106
10. Control 0 112 60 48 768 --- 7.0 x 10 2.2 x 10 3.6 x 10

* 3rd day for experiments 5-10
** 6th day for experiments 5-10

*** TNTC - Too numerous to count

Conditions: Mean Atmospheric Temperature: 290C

Volume of Raw Sewage: 12 1
Depth: 15 cm

Table 4. 5-day Biochemical Oxygen Demand (BOD5) and Bacteria Concentrations in
100 mg/l Phenol Solutions With and Without (Control) Water Hyacinths

Fresh Total BOD mg/l mg BOD mg BOD removed/ Bacteria, Count/100 ml
Experiment Mass 5 5 gCount/100 ms
WHs, g Initial 7th Day removed/7 days (7 day exposure) Initial 7th Day

1. Control 0 160 114 184 --- 106 x 105 250 x 104

2. Control 0 160 120 160 --- 148 x 10 51 x 10
5 4
3. Control 0 160 115 180 --- 115 x 10 174 x 10

4. w/WHs 155 160 35 500 3.2 110 x 10 61 x 10

5. w/WHs 200 160 37 492 2.5 37 x 10 82 x 10
5 4
6. w/WHs 298 160 35 500 1.8 143 x 10 24 x 10

7. Control 0 235 136 396 --- 3 x 10 34 x 10
4.
8. Control 0 235 115 480 --- 1 x 10 TNTC

9. Control 0 235 116 476 --- 2 x 10 ---

10. w/WHs 120 235 26 836 7.0 1 x 104 60 x 106

11. w/WHs 242 235 15 880 3.6 1 x 10 3 x 10

12. w/WHs 293 235 29 824 2. 8 1 x 104 TNTC

Conditions: Mean Atmospheric Temperature: 29�C

Volume of Phenol Solution: 4 1

Depth: 13 cm

tion prior to discharge.

DESIGN PROPOSAL FOR DOMESTIC WASTEWATER TREATMENT
SYSTEMS USING HIGHER PLANTS

Field and laboratory data collected during the past five years at
NSTL indicate that a combination of conventional sewage technology and
the controlled growth of higher plants such as the water hyacinth and
duckweed can produce cost effective, advanced wastewater treatment Sys-
tems in warm to moderate climate zones. Proposed designs for sewage la-
goons using water hyacinths and duckweeds to treat domestic wastewater
for small communities of 500 people or less is shown in Figure 2. The
same type system for treating wastewater for communities of 1000 to 3000
people is shown in Figure 3. In arriving at the following proposed de-
sign characteristics, four problems had to be addressed: (1) sludge ac-
cumulation, (2) odor control, (3) BOD reduction, and (4) total suspended
solids removal. Nitrogen and phosphorus removal must also be considered
if tertiary treatment is required.
In order to minimize sludge handling problems, deep lagoons approxi-
mately 3 m (10 ft) in depth, with small surface areas appear to be the
most practical method for initial treatment and sludge collection. Deep
lagoons receiving raw sewage have advantages and disadvantages. These
lagoons act as anaerobic digesters, producing foul odors due to the lib-
eration of hydrogen sulfide gas during the sewage digestion process.
Approximately 114g (0.25 lb) of elude per person is generated daily in
domestic sewage. The total settled solids in sewage can be reduced by
40-50% and given off as gases if the sludge is anaerobically digested.1
Yearly sludge accumulation per person after anaerobic digestion is ap-
proximately 23 kg (51 lbs). The proposed design in Figure 2 should allow
approximately 100 years of operation with 500 people before presenting a
sludge removal problem. The design in Figure 3 should operate for ap-
proximately 30 years with 3,000 people before sludge removal is needed.
Anaerobic digestion for the initial treatment of raw sewage not only
reduces the sludge solids, but also reduces the complexity of BOD sub-
stances and the concentration of toxic heavy metals when present. Sul-
fides produced during anaerobic digestion will react with soluble heavy
metal ions to form a metallic sulfide precipitate that is relatively in-
soluble at pH near 7.0. Approximately 1.8 to 2.0 mg of heavy metals can
be precipitated as metal sulfides by 1.0 mg of sulfide (5~).'
In order to eliminate odor emission when anaerobic treatment is
used in the first step, it is essential for the first lagoon to contain
a photosynthetic aerobic zone, mechanically aerated surface zone, sur-
face sealer, or a combination of these features. The most reliable
means of assuring an aerobic surface zone for odor control appears to be
the limited use of surface aerators. Studies in Mississippi with the
system depicted in Figure I have shown that the use of surface aerators
during dark hours and photosynthetic algae during daylight hours effec-
tively controls odors with minimum aeration cost. A limited amount of
research has been conducted by NASA on the use of duckweed as a photo-
synthetic surface sealer for small anaerobic lagoons. The use of duck-
weeds would eliminate the energy requirements of supplemental mechanical
aeration. BOD5 reductions in excess of 70% at hydraulic detention
times of 1.2 days in anaerobic ponds was noted by Oswald et al. 3Deten-
tion periods of up to 5 days were recommended to compensate for

188

*5 HP FLOATING AERATORS

SURFACE
~~~* $1.24 ha surface (0.5 acre),
3.05 m deep (10 ft)

182.9 m (600 ft) -!
T

CDo WATER HYACINTHS
Ln

,91 m deep (3 ft)

WATER HYACINTHS

WATER HYACINTHS - EFFLUENT

Figure 3. Water Hyacinth Sewage Treatment System Which Will Achieve Secondary
to Tertiary Treatment Levels for Wastewater from 1000 - 3000 People.

.189

*5 HP/FLOATING
AERATOR
NIGHT USE ONLY

DUCKWEED LA-AGE
COVERED SURFACE SURFACE
1-2 CM * *

Anearobic Ponds
are .09 ha (0.25 acre)
and 3.05 m deep (10 ft)

WATER WATER DUCKWEEDS
DUCKWEEDS
HYACINTHS ~ HYACINTHS

tr~
Lf

CIS

Clarification
Ponds are
.91 m deep
(3 ft)

f9.14 m (30 ft"' I
I I IJ
EFFLUENT EFFLUENT REQUIRE RIP-RAP
FOR REAERATION
OF EFFLUENT.

Figure 2. Water Hyacinth, Duckweed and a Combination Water Hyacinth-Duckweed
Sewage Treatment Systems Which Achieves Secondary to Tertiary Treat-
ment for Wastewater from 250-500 People.

190

decreased bacterial activity during cold weather. Detention times of 15
and 5 days are proposed for the anaerobic lagoons in Figure 2 and 3 re-
spectively. When surface aerators are used, additional BOD removal at
the rate of 24 kg/ha/day can be achieved.
The designs shown in Figures 2 and 3 are based on influent waste-
water containing 150 mg/i BOD5. These designs assume a 50% BOD5 removal
in the first anaerobid lagoon. Water hyacinth covered lagoons can be
expected to remove approximately 1045 kg BOD5/hectare every seven days or
148 kg BOD5/hectare/day based on the results of the experiments and field
data presented in this paper and an average standing crop of 220 mt/hec-
tare (100 ton/ac).
If tertiary standards must be met, the total nitrogen and phosphorus
must be reduced to 3 and 1 mg/I, respectively. Assuming a sewage influ-
ent containing 35 mg/i kjeldahl nitrogen and 7 mg/i total phosphorus with
a daily increase and harvest rate of 5% plant mass, then the design in
Figure 2 should achieve tertiary treatment levels for the waste of 250
people and Figure 3 for 1500 people. This is assuming a standing crop of
220 mt/hectares and a 0.91m (3 ft) depth in the elongated water hyacinth
lagoons shown in Figures 2 and 3. Total suspended solid concentrations
are reduced by water hyacinth coverage due to shading effects and pos-
sibly nutrient reduction.
Plant material harvested from this type system can be processed into
usable products. Studies at NASA have shown that the simplest product
produced from water hyacinths is compost, a complete plant growth media
produced by aerobic decomposition. Plants such as cucumbers, squash,
corn, tomatoes, peas, sorghum, etc., have been grown successfully using
decomposing water hyacinths as the sole source of soil and food.
Another potential product from the harvested biomass is methane.
Methane is produced by anaerobically digesting the fresh plant material.
Current experiments at NSTL demonstrate that 0.18 m3 (6.3 ft3) of methane
can be produced per dry kilogram of plant material in 24 days or less
digestion time at 370C.
An engineering handbook on the construction of vascular aquatic
plant wastewater treatment systems will be available by January 1980.

191

REFERENCES

1. Gloyna, E.F., J. F. Malina, Jr. and E. M. Davis. Ponds as a Waste-
water Treatment Alternative. Water Resources Symposium Number Nine.
Center for Research in Water Resources, College of Eng., Univ. of
Texas at Austin (1976).

2. Middlebrooks, E. J., N. B. Jones, J. H. Reynolds, M. F. Torpy and
R. P. Bishop. Lagoon Information Source Book, Ann Arbor Science
Publishers, Inc., Ann Arbor, Michigan (1979).

3. Oswald, W. J., C. G. Golueke and R. W. Tyler. "Integrated Pond Sys-
tems for Subdivisions," Journal Water Pollution Control Federation,
39 (8), 1289 (1967).

4. Oswald, W. J. "Waste Stabilization Lagoons," Proceedings of a Sym-
posium at Kansas City, MO. 33-40 (1960).

5. Wolverton, B. C. and Rebecca McDonald. The Water Hyacinth: From
Prolific Pest to Potential Provider, AMBIO, 8 (1), 1-9 (1979).

6. Wolverton, B. C. and Rebecca McDonald. Upgrading Facultative Waste-
Water lagoons with Vascular Aquatic Plants. Journal Water Pollution
Control Federation, 51 (2), 305-313 (1979).

7. Wolverton, B. C. and Rebecca McDonald. Wastewater Treatment Utiliz-
ing Water Hyacinths. Proceedings of the 1977 Natl. Conf. on Treat-
ment and Disposal of Ind. Wastewater and Residue. Univ. Houston,
Texas, 205-208 (1977).

8. Rebecca C. McDonald. A Comparative Study of a Domestic Wastewater
Lagoon With and Without Water Hyacinths. NASA Tech. Memorandum.
TM-X-72735 (1979).

9. Wolverton, B. C. and Rebecca McDonald. Water Hyacinths for Upgrad-
ing Sewage Lagoons to Meet Advanced Wastewater Treatment Standards:
Part II. NASA Tech. Memorandum TM-X-72730 (1976).

10. Standard Methods for the Examination of Water and Wastewater. 14th
Ed. American Public Health Association, Washington, D.C. (1975).

11. Metcalf & Eddy, Inc. Wastewater Engineering: Collection, Treat-
ment, Disposal. McGraw-Hill Book Co. (1972).

12. Wolverton, B. C. and Rebecca McDonald. Water Hyacinth Productivity
and Harvesting Studies. NASA/ERL Report No. 171, NSTL Station,
MS 39529 (1978).

192

DEVELOPMENT OF HYACINTH WASTEWATER TREATMENT
SYSTEMS IN TEXAS

Ray Dinges, Texas Department of Health, 110 West 49th Street,
Austin, TX 78756

INTRODUCTION

Field observations revealed that turbid, enriched waters (municipal
wastes, cannery wastes, and sugar refinery wastes) were clarified and
stabilized after passage through natural water areas covered by water
hyacinth (Eichhornia crassipes (Mart.) Solms). Staff of the Wastewater
Technology and Surveillance Division began to speculate on the possi-
bility of utilizing controlled hyacinth culture for improving stabili-
zation pond effluent. Other possible uses of hyacinth culture envi-
sioned included the clarification of turbid river waters used as do-
mestic water supply sources and the demineralization of brackish ground
waters.

Simple, solar-powered stabilization ponds have a number of positive
advantages, including the reduction of adverse chemical and biological
agents (Dinges, 1979). A decided disadvantage is that their effluents
are filled with single-celled algae, nutrients, and excessive levels of
fecal organisms (Dinges and Rust, 1970). Several hundred stabilization
pond systems are used in Texas for treating municipal, industrial and
agricultural wastewaters. Many pond systems discharge to small streams
and to watercourses with intermittent flow. Some of these waterways
enter reservoirs utilized as sources for domestic water supply and for
recreation. Sludge banks and foul, stagnant pools of water are not at
all uncommon below the discharges of stabilization ponds. Smallhorst
(1963) expressed the need for research to improve stabilization pond
effluent quality by biological means.

Preliminary observations on hyacinths grown in wastewaters were
commenced in 1970. A basin was constructed at a private residence in
Dale, Texas for that purpose. The basin was about 2-m in width, 9-m in
length, and operated at a a depth of 1-m. Septic tank effluent was
diverted into the basin and the desired water level maintained by
periodic addition of well water. Plants grew well in the diluted
septic tank effluent and waters at the lower end of the basin remained
clear.

193.

Field Study

An opportunity was afforded to evaluate the effect of hyacinths on
water quality in 1972. The City of Gregory, Texas is served by an
overloaded wastewater treatment facility. Plant effluent discharges
into a drainage ditch which empties into a 1.2-ha impoundment (Butterfly
Lake). Overflow from Butterfly Lake goes into Corpus Christi Bay. The
ditch and the lake have been covered by hyacinths for years.

Hyacinths were sprayed with broadleaf herbicide on two occasions in
November, 1972. A field study was conducted from July through October,
1973 to determine water quality changes during regrowth of the plants
(Dinges, 1973-1976). Water overflow from Butterfly Lake at that time
was of good quality and contained 2 mg/l BOD5 and 10 mg/l of total
suspended solids. The unplanned hyacinth wastewater treatment system at
Gregory is still functioning. Primary study emphasis was not directed
towards organic quality improvement, but upon the capability of hyacinths
to demineralize water. Water samples for chemical anaylsis were collected
weekly from a 650-m section of the ditch having an estimated detention
time of about 8 days. Results indicated a mean reduction in total
dissolved solids of 59.3%. A portion of the observed decrease may
possibly be attributed to ion exchange mechanisms associated with the
peaty organic deposits present in the ditch.

Pilot Studies

Facilities. The City of Austin was approached and agreed to
provide a pilot scale experimental hyacinth culture basin at the Williamson
Creek wastewater treatment facility in November, 1974. The pilot unit
was completed in April, 1975. See Figures 1 and 2.

Two wastewater treatment plants are located at the Williamson Creek
facility. Plant A consists of an aerated basin equipped with a surface
aerator, a clarifier and three stabilizaiton ponds. Sludge is returned
to the aerated basin with excess sludge and clarified effluent being
discharged to the ponds. The three ponds, which are about 1.2-ha in
size, are operated in series and at a depth of about 2.44-m. There is
no discharge from the system and excess water is pumped to a large pond
of Plant B by an electric driven pump rated at 31.54-1/sec that is
activated by a float switch. Design capacity of Plant A is 757-m3-d and
it receives controlled flows of 1,325 to 1,438-m3-d.

Plant B receives the remainder of daily flow, which averages 12,500-
m .d. This plant consists of two aerated basins operated in parallel
and three stabilization ponds. The three ponds are 18.2-ha, 15.4-ha and
13.0-ha in size and are 2.7-m deep.

An excavation 9.1-m wide and 64-m long (585-m2) was constructed
between Pond 3 of Plant A and Pond 1 of Plant B and divided into four
sections by barriers of crushed stone 10 to 15-cm in diameter. Section 1
was 30.5-m in length and 0.6-m in depth. One half of the second
section, which was 18.3-m long, was 0.6-m deep, and the other half was
3-m deep. Both of the remaining sections were 7.6-m long and 0.8-m
deep.

194

Fig. I Austin, Texas-Williamson Creek Experimental
Hyacinth Treatment P'ilot System, 1975.

(Courtesy of S. Hart)

195

FIG, 2 CITY OF AUSTIN, TEXAS
WILLIAMSON CREEK EXPERIMENTAL
HYACINTH WASTEWATER TREATMENT FACILITIES

.U CLARtERATED
UMP aim BASIN
PLANT B-
STAB, POND 1
1 - , I NFLUENT
18.2-HA PLANT A

PILOT HY'ACINTH STAB. STAB
/ SCALE, ULTURE POND 2 POND 1
H IW, ,EU. BASIN
(ABANDONED!1,2-HA 1,2-HA 1,2-HA

CLo CONTACT BARRIECK
(TURE SE) BARRIER

During the first study phase (June 1975 to February 1976), the
experimental system was furnished with water obtained from Pond 3 of
Plant A using an electrically-driven centrifugal pump rated at 3.15-
1/sec. A 5-cm diameter steel pipe was used for water delivery. A waste
line with a gate valve was provided to regulate inflow by discharging
excess water back to the stabilization pond.

A more enriched water was acquired from Pond 1 (18.2-ha) of Plant B
in the second study phase, which extended from May through August, 1976.
Water was provided to the experimental facility by gravity flow through
a 6.4-cm diameter steel pipe equipped with a gate valve for flow control.

A rectangular plastic (polyethylene) container 35.5-cm x 12.7-cm
was placed in each section to serve as a sedimentation pan.

Mean water depth in the experimental system during the first study
phase was 1-m. At a flow rate of 1.26-1/sec, theoretical system deten-
tion time was 5.3 days. Operational mean water depth was maintained at
85-cm in the second study phase and the detention period was 4.5 days at
a flow rate of 1.26-1/sec. A 1.26-1/sec rate of flow was found to be
about the maximum hydraulic loading that could be accpeted without
causing breakthrough of solids. Flow introduced into the system amounted
to 109-m3.d, or the wastewater contribution of a community of about 300
people.

Surface organic loading on the experimental system was 4.34 g/m2.d
BOD in the first study phase and 8.93 g/m2.d in the second study phase.
Infduent-effluent samples were collected weekly and analyzed by accepted
procedures.

Results. Extensive testing of system influent-effluent revealed
that significant quality improvement in stabilization pond effluent was
obtained by hyacinth treatment. Detailed results of the pilot studies
have been reported upon previously (Dinges, 1976). A brief summary
of selected water quality parameters evaluated are presented in Table 1.

Approximately 50 percent of influent phosphorus (P) and 80 percent
of potassium (K) were removed in summer months. Leaching of P and K
from the system occured during the winter. The standing crop of
hyacinths at the end of a growin8 season represented a dry weight
biomass production of 3,184 gm/v . This compares favorably to the
similar measurement (2,970 gm/m ) made by Wooten and Dood (1976). Mean
moisture content of the plants was 94 percent and they had a mean ash
content of 19.6 percent. Hyacinths accumulated heavy metals, other
minerals, and trace organics from the water during the growing season.

197

Table 1

Pilot Studies-Indicated Mean Reductions in
Selected Wastewater Quality Parameters
Affected by Hyacinth Treatment

First Study Phase Second Study Phase
June 1975-February 1976 May 1976-August 1976

Influent Effluent % Reduction Influent Effluent % Reduction

Chlorophyll a,
mg/l 0.351 0.028 93 0.35 0.017 95
BOD5, mg/l 22.6 5.2 77 46.5 5.7 87
TSS, mg/l 43.3 7 84 117 7.5 93
COD, mg/l 84 40 52 184 51 72
MBAS, mg/l 0.17 0.03 82 0.13 0.04 66
TN, mg/l 8.16 2.47 69 9.94 3.59 63
TON, mg/1 4.33 1.25 71 7.59 1.63 78
Fecal Coliform
Bacteria/100ml 2895 31 98 27423 363 98

198

Pollutant Removal. Waters of a basin completely covered by a
hyacinth mat are quite still, have a pH near neutral, and are almost
totally shaded. Temperature fluctuations are moderated and stratifi-
cation prevails during the summer. Phytoplanktonic algae growth is
precluded due to light restriction and sedimentation is enhanced in the
stilled waters. Coagulation of incoming algae cells and heavy sludge
deposition occurs in the influent vicinity of the basin. Surface basin
waters contain low levels of dissolved oxygen and bottom waters are
anoxic. Free carbon dioxide levels are high. Hyacinth roots serve as a
barrier to the horizontal movement of suspended solids.

The hyacinth overstory; surface water; root area; free water beneath
the mat; and the basin bottom may be viewed as being biotic zones. Most
biota reside in the surface and root zones. Extensive biological activity
occurs in the influent region of a basin, resulting in a veritable
"train" of organic debris, much of which is not readily biodegradable.
Bacteria, fungi, predators, filter feeders, and detritovores are present
in large numbers. The biological reduction, oxidation, and consumption
processes performed by the complex community of organisms in a hyacinth
culture basin serve to stabilize water by releasing stored potential
energy. Organic residues accumulate in the basin due to the physical
* ~~processes of filtration and sedimentation.

Hyacinths obtain carbon dioxide from the air. Otherwise, hyacinth
biomass is derived from soluble substances from the wastewaters in which
they are growing. Plant uptake of materials from the water is restricted
to the period of active growth. The overall improvement of waters
passing through a culture basin may be attributed to the removal of
suspended particulates fostered by the physio-chemical and biological
factors related to the habitat provided. This fact becomes quite clear
when waters exiting a basin are of high quality even in the winter when
the hyacinths are frozen down to the water surface.

Plant Scale Study

Following the successful conclusion of the pilot studies, a full-
scale facility treating an amount of wastewater which might be expected
from a population of about 3,500 people was provided and placed into
operation. See Figures 2 and 3. The experimental hyacinth culture
basin is being operated as if it were an integral unit of the Williamson
Creek wastewater treatment plant in order to learn more about operational-
management procedures. Routine effluent quality evaluation is restricted
to those parameters commonly included in discharge permit requirements.

Facility. The last 1.2-ha stabilization pond of Plant A was drained,
cleaned, and converted into a hyacinth culture basin in October, 1977.
A crushed stone barrier approximately 2.4-in in height and 21-in x 21-in in
size was constructed at the lower end of the basin to prevent escape of
the plants and to create a clear outlet zone. Influent is admitted to
the basin from the second stabilization pond by an adjustable gate.
Water depths have been varied from 0.7-in to 1.3-in in the hyacinth
culture basin. System effluent is transferred to one of the nearby
stabilization ponds of Plant B by an electrically driven pump rated at
31.5-1/sec. 3Flow to the wastewater treatment plant varies between 1,325
and 1,703 m3.d. A somewhat lesser amount of water passes through the
hyacinth basin due to seepage and evaporation losses. Test results from
October, 1977 until August, 1979 are presented in Table 2.

199

Fig. 3 Austin, Texas-Outlet Area of the Williamson
Creek Experimental Hyacinth Treatment System, 1979.

200

Table 2

Influent-Effluent Quality - Williamson Creek
Full-Scale Hyacinth Treatment System.

October 1977 - August 1979

Influent n Effluent** n % Reduction

BOD5, mg/1 41.9 (40) 12 (41) 71
TSS, mg/l 40 (41) 8.8 (42) 78
Fecal Coliform/ 5388* (28) 302 (31) 94

*One test result of 10 x 106 organisms not used in calculation of mean
** Includes data collected during two winter periods when plants had
been frozen and were in a state of decay.

201

The culture basin was drained, cleaned and planted with hyacinths
in May, 1979. Basin debris removed was buried in trenches at the plant
site.

Other Municipal Hyacinth Treatment Systems

All municipal hyacinth treatment systems in Texas are considered to
be experimental at the present stage of process development. Hyacinth
treatment facilities are being monitored to learn more about system
design, operation, and management procedure.

Austin-Hornsby Bend Sludge Treatment Ponds. Excess activated
sludge from the Govalle and the Walnut Creek wastewater treatment plants
is transferred to the Hornsby Bend pond system by force main. The
facility consists of a 34.4-ha pond followed by two other ponds 26.3-ha
and 16-ha in size. See figures 4 and 5. The system receives about
7,570 m3'd of excess activated sludge. A 1.4-ha hyacinth culture basin
has been provided to treat the sludge pond system overflow. The upper
end of the rectangular culture basin is quite shallow and deepens
gradually towards the outlet. Maximum water depth is about 2.46-m and
the mean basin depth is estimated to be 1.23-m. A section near the
outlet has been fenced to provide a clear area and to serve as a chlorine
contact zone. Chlorine is introduced at the fence line through perforated
plastic tubing. A 900 V-notch weir has been installed in the outlet
drop box for flow measurement. Hyacinths were planted in the basin in
late May, 1979. About 6,050 m3.d passes through the culture basin.
Very little change between influent and effluent quality is evident at
this hydraulic loading rate.

San Juan-Rio Grande Valley Pollution Control Authority. San Juan
has a population of about 6,800 persons. Mean daily inflow to the
wastewater treatment plant is 1,514 m , with peak flows being around
3,785 m3.d. Influent to the plant is usually septic. The facility
consists of a 0.97-ha raw sewage pond provided with a surface aerator; a
0.97-ha stabilization pond; two hyacinth culture basins 1-ha each in
size; and a chlorine contact chamber. See Figures 6 and 7. Mean
organic loading on the stabilization ponds is about 15.6 g/m2'd of BOD5,
or four times greater than suggested in the Texas "Design Criteria for
Sewerage Systems." For short periods during canning operations, plant
ponds may receive more than 30 times that amount of organic loading
which would be appropriate. The surface aerator is to be enclosed
within a small diked area within the raw sewage pond in the near future
in order to increase oxygen transfer efficiency and treatment capability.
System effluent quality from April, 1978 to March, 1979 is presented in
Table 3.

The two hyacinth basins, which have been designated as A and B may
be operated at depths from 15-cm to 1.4-m. Water from the second
stabilization pond is delivered to the basins through pipes equipped
with gate valves. Culture basins receive variable flow rates as there
is little excess storage capacity in the feeder stabilization pond.

202

FIG. 4 CITY OF AUSTIN, TEXAS
HORNSBY BEND SLUDGE TREATMENT FACILITY

\,, SLUDGE
POND
X16-HA 1 1-

EFFLUE

, INFLENT
POND 3 /a

L-I NLET

~HYAC INTH
BASIN
,,[ 1,4-HA
OUTF.L
EFFLUENT~ i~
DROP Box_ ARRIER

CL2

203

Fig. 5 Austin, Texas-Ifornsby Bend Hyacinth Treatment
System, 1979.

204

FIG, 6 RIO GRANDE VALLEY POLLUTION
CONTROL AUTHORITY
SAN JUAN, TEXAS

TAB, POND J
097-HA
AERATOR
'~ RAW
WASTEWATER

' _~ o0,97-HA

DISTRIBUTOR
DI STRI UTOR / 24,6-M

HYACINTH BASIN A
BtARRIE

CLON _-HA 1,0-HA
CONTACT
EFFL EN' 'B '-
ARRIER " +
BARRIER

EFFLUENT

205

Fig. 7 San Juan, Texas-Hyacinth Basin A, 1979.

(Courtesy of E. Nordmeyer)

206

Table 3

San Juan Effluent Quality Data*

April, 1978 - March, 1979

Annual Mean Maximum Recorded

BOD5, mg/l 23 40
TSS, mg/l 24 54

* One hyacinth unit in operation--Basin A.

207

Water is distributed to Basin A through a 24.6-m length of plastic
pipe having 5-cm diameter openings at 3-m intervals. The basin outlet
is located opposite the distribution pipe at a distance of 115-m. In
designing a culture basin, it should be assumed that water will flow
directly from the inlet to the outlet. Therefore, the "minimum effec-
tive zone" of Basin A is only 0.13-ha. It is planned to extend the
distribution pipe along the entire inlet side of the basin (95.3-m) at
the time the unit is drained for removal of hyacinths and basin debris.
This will increase the effective zone to 0.52-ha, or one-half of the
total basin area.

A wire screen is located a short distance in front of the outlet
structure. An additional wire fence creating a clear zone of about 185
m will be installed in the future to allow for reaeration of the water
prior to discharge and prevent the discharge of debris drawn from
beneath the mat by outflow velocity. An open water area around the
outlet is especially important in the Rio Grande Valley where the
natural waters contain elevated sulphate levels.

The San Juan hyacinth wastewater treatment system is being tested
in cooperation with the Rio Grande Pollution Control Authority. Basin A
has been operated at various depths and flow rates since July, 1978.
Water samples are collected by personnel of the Rio Grande Valley
Pollution Control Authority, refrigerated, and forwarded to the Depart-
ment central laboratories for analysis. Test results are presented in
Table 4.

Alamo-Rio Grande Valley Water Pollution Control Authority. Alamo
has a population of about 5,500 persons. Mean daily inflow to the3
wastewater treatment plant is 1,514 m , with peak flows of 3,785 m .
The plant facility consists of an Imhoff tank; a trickling filter; an
aerated basin equipped with a surface aerator (2,838 m capacity); two
4.04-ha stabilization ponds operated in parallel; two hyacinth culture
basins (1.35-ha and 1.05-ha); and a chlorine contact tank. See figures
8 and 9.

Domestic wastewater flow is estimated to be 1,060 m3.d and is
treated in the Imhoff tank and trickling filter. Cannery wastes and
domestic effluent are introduced to the aerated basin. One-half of the
discharge from the aerated basin is diverted to each of the stabilization
ponds, thence into the hyacinth culture basins. Organic loading on the
stabilization ponds is estimated to be about 4.6/m2-d of BOD5. Hyacinth
culture basins were recently completed and planted with hyacinths.
Effluent quality of the system from April, 1978 through March, 1979
prior to the introduction of hyacinths averaged 33 mg/l BOD5 and 86 mg/l
TSS. Monthly means of effluent BOD and TSS were 38 and 68 mg/l in May,
1979 and 50 and 82 mg/l in June. The basins were partially covered by
hyacinths during this period (<25%).

San Benito. San Benito has a population of about 17,500 pirsons.
Mean daily flow to the wastewater treatment facility is 2,460 m , with
peak flows up to 6,737 m3-d. Plant influent is septic. The treatment
facility consists of a 7.86-ha raw sewage stabilization pond, followed
by four more stabilization ponds having a total surface area of 13-ha.
The last pond has been divided into three sections by earthen dikes to
serve as an experimental hyacinth treatment facility. Basins 1 and 2
are 0.8-ha each and Basin 3 is 2-ha in size. The three basins are
designed to operate in series. About one-half of Basin 2 was covered by
hyacinths and Basin 3 was completely covered with plants when the
facility was inspected in June_ 1979. See figures 10 and 11.

208

Table 4

San Juan-Rio Grande Valley Pollution Control Authority
Effluent Quality of Hyacinth Basin A at Various Loadings
and Operating Depths

July, 1978 - May, 1979

3
n Raw Sewage Basin A Effluent Depth, cm. Flow, m Total % Removed

D5'/ TSS, BOD5, mg/l TSS, mg/1 BOD5 TSSmg/
BOD5 ~ ~ ~ ~ ~ ~ ~~S, mg/l BOD5 T S S l

1 90 111 20 30 61 870 77.7 72.9
4 86.2 113.2 9.2 <11.2 91 852 89.3 90.1
7 265.7 221.5 35 30.4 91 1552 86.8 86.2
10 319.4 282 31 32.3 137 1855 90.3 88.5

FIG. 8 RIO GRANDE VALLEY
POLLUTION CONTROL AUTHORITY
ALAMO, TEXAS
IMHOFF TRICKLING
ILTER
DOMESTICt--
WASTEWATER A
AC___ --. CANNING
AERATOR. '"- WASTEWATER

STAB. STAB,
POND 1 POND 2

4,04-HA 4,04-HA

ISTRIBUTOR DISTRIBUTOR
24.6-M
EFFLUENT-1 I( ++

CL2 CONTACT \UYAC NTH HYACINTH BASIN A
s 5J, 05-HA 1,35-HA4+

EFFLUENT BARRIER EFFLUENT BARRIER

210

Fig. 9 Alamo, Texas-Distribution Pipe of Hyacinth Basin B.
Basin A in Background, 1979.

(Courtesy of H. Nordmeyer)

211.

FIG, 10 CITY OF SAN BENITO, TEXAS

RAW WASTEWATER

INLET
3-HA
7,86-HA

STAB. STAB,
POND 2 POND 1

9 1 PO ND 3
SIN,

S2D 3

FLUENVT

212

Fig. 11 San Benito, Texas-Two of Three Hyacinth
Basins, 1979.

(Courtesy of H. Nordmeyer)

213

A wire fence barrier is located a short distance in front of the
outlet. Changes in the design and operation of the system are being
considered. Mean effluent quality from April, 1978 through March, 1979
averaged 17 mg/i BOD5 and 35 mg/i TSS. The means of effluent BOD5 and
TSS were 17 and 20 mg/I for June, 1979.

Rio Hondo. Rio Hondo has a population of about 1,300 persons.
A 0.8-ha raw sewage stabilization pond was constructed in 1950 to serve
the city. The pond became filled with sludge over the years. Effluent
quality from the pond had deteriorated to the extent that it was compar-
able to that of the raw wastewater. Hyacinths were planted in the pond
a few years ago. Pond effluent quality improved somewhat. Sludge
deposition was enhanced by the hyacinths and increased in depth until
only a few centimeters of water remained in the pond.

Three 0.41-ha hyacinth culture basins have been constructed.
Basins 1 and 2 are rectangular and Basin 3 is square. The raw sewage
stabilization pond was bypassed and raw wastewater now discharges to
Hyacinth Basin 1. Basin 1 and 2 are connected by piping. Water from
Basin 2 is pumped to Basin 3, with a pump controlled by a float switch.
Most of the surface areas of the three basins are now covered by plants.
See figure 12.

Raw sewage flow to the system is about 454 m3.d. Hyacinth Basin 1
has an organic loading estimated to be 19.7 g/m2-d of BOD . Total
system surface area has an organic loading of 6.6 g/m2.d of BOD
Effluent quality from July, 1978 through May, 1979 was 16 mg/i BOD5 and
24 mg/i TSS. Monthly means of effluent BOD and TSS were 10.5 and 6 mg/i
in May and 14.5 and 12 mg/i in June, 1979.

The city plans to remove the sludge and restore the dikes of the
raw sewage stabilization pond and place it back into operation. Modifi-
cations are also to be made to improve distribution of water through the
hyacinth culture basins.

Design Considerations

Hydraulic Loading. Neuse (1976) conducted a study to define the
hydraulic capability of a pilot hyacinth basin designed to remove
suspended solids from stabilization pond effluent. A pilo unit having
a channel configuration and with a surface area of 18.58 m was constructed
at the Williamson Creek wastewater treatment plant in Austin, Texas.
The plastic lined channel had a width to length ratio of 12.5:1.
Hydraulic loading rate on the system varied from 0.44 1/sec to 0.63 I/sec.
Neuse concluded from his study that a second identical unit operated in
series would be as efficient in solids removal as the first unit, but
the amount of solids removed would be less. He postulated that a
culture basin could be sized properly for any given hydraulic loading
rate and proposed a broad rectangular configuration (channel replication)
with even distribution of influent on one side and the discharge of
effluent over an extended weir along the opposite side.

214.

FIG, 12 CITY OF RIO HONDO, TEXAS

RAW WASTEWATER

X �
HYACINTH HYACINTH : RAW
BASIN A I BASIN B WASTEWATER
0.41-HA O,41-HA � STABILIZATION
: POND
(FUTURE USE)
: 0,8-iHA

PUMP
TRANS FER

HYACINTH
BASIN C
0,41-HA
UTLET

4EFFLUENT

215

operation of the Williamson Creek pilot hyacinth treatment system
had revealed that hydraulic loading is a foremost design consideration.
The basin produced low TSS levels at a sustained flow rate of 1.26 I/sec.
Increasing the flow to 1.89 1/sec resulted in solids breakthrough. A
culture basin which is not hydraulically overloaded should consistently
produce <10 mg/l BOD5 and TSS. Organic loading on a basin should normally
be <10 g/m2.d of BOD5 when input is stabilization pond waters.

When the pilot scale system was abandoned and allowed to dry out
after two years operation, it was noted that most sludge accumulation
had occurred in a semi-circle near the influent. The dried sludge layer
was about 10-cm thick. Drainage of the full-scale hyacinth system at
Williamson Creek for cleaning after two years of continuous operation
revealed a fan-shaped area in the influent vicinity with a sludge (wet)
depth of about 0.6-in.

An elongated rectangle may be satisfactory in some instances, but
it is certainly not an efficient configuration for a hyacinth culture
basin. The broad rectangular shape would be efficient, but the extended
discharge weir and the barrier required would be costly. It is also
difficult to maintain the integrity of an extended weir. It was sug-
gested by S.W. Hart, Chief, Engineer, Wastewater Technology and Surveil-
lance Division, that a triangular basin might be appropriate. Influent
could be distributed over a broad front and an even flow throughout the
entire basin area would be assured. However, triangular basins do not
represent efficient land use. This objection was met by joining the two
triangles to form a rectangular shaped unit as depicted in Figure 13.
It is believed that this suggested basic design would maximize efficiency
and be economical for open basins. Determination of optimum depth and
detention is contingent upon the provision of a basin with hydraulic
efficiency.

The Texas Department of Health recommendations for the construction
and operation of hyacinth basins for upgrading stabilization pond
effluent is in the Appendix. Adequate information is available for the
design of hyacinth culture basins which are to be employed in tropical
or sub-tropical regions. Optimum design parameters will be required in
temperate climates using greenhoused hyacinth culture basins.

Discussion

Objectives. Residues (organic debris, animals, fish, plants, etc.)
resulting from advanced biological wastewater treatment (ABWT) are
viewed as being valuable products to be used for food, fuel, and fertil-
izer (National Academy of Sciences Report, 1979). There is an increasing
universal interest in using wastewaters for the production of useful
products (Dinges, 1980). Future development of ABWT is not restricted
to technical consideration alone, but will be determined by social
(philosophical) political and economic factors.

216

FIG, 13 SUGGESTED
BASIC HYACINTH CULTURE
BASIN DESIGN

DISTRIBUTOR +EFFLUENT

INFLUENT .aI _ s .** *s.'� �*

4.4.4. I X . BARRIER

It * :
l t/ � t*
/ ALTERNATE
1-M DEPTH
1-$1 � : CULTURE
BASIN
BERM
111 :
Attt �
to .

Ittt t.
BARRIER---

DROP BDISTRIBUTOR

0,5% SLOPE RAIN

DRAIN
PIPE

217

Hyacinths may be used for livestock feed, fuel generation, and to
improve micro-nutrient levels and moisture retention capability of soils
in arid areas. Wastewaters have been considered as a liability in the
past. Hyacinth culture is a means to reduce the negative economic
impact of wastewater renovation.

A dichotomy exists, however, between the two desirable goals of
optimum, efficient wastewater treatment and maximum hyacinth production.
Efficient nutrient elimination is an objective of wastewater treatment.
Conservation and optimum utilization of fertilizer is a goal of hyacinth
production. Hyacinth production would require large land area and
entail costs for harvest machinery, labor, and energy. These expenditures
would need to be balanced against the value of the product obtained.
The potential quantity of product would be limited by the volume of
wastewater available. It follows that cities having large wastewater
flows would be the most likely candidates for mass hyacinth production.

Nutrient Management. Conserving and circulating nitrogen would be
a paramount consideration to maximize production. Use of plant material
for methane generation would contribute to nitrogen conservation as it
is not lost during anaerobic fermentation. Supernatant return to culture
units would restore nitrogen and permit the fixation of additional
carbon via plant growth.

Hyacinths accumulate large amounts of potassium, but it is unlikely
that this macro-nutrient would be limiting in most instances. Adequate
micro-nutrients would be available in incoming wastewaters. Phosphorus
is present in wastewaters at levels which far exceed plant growth require-
ments. One possible economical means of excess phosphorus removal might
be the addition of aluminium sulphate (alum) to the return digestor
supernatant. Resulting sludge would be removed from the system.

Much more efficient nitrogen removal may be obtained in properly
designed stabilization ponds than by hyacinth culture if the goal being
sought is effective wastewater treatment. Nitrogen reduction could best
be accomplished by utilizing a combination stabilization pond--hyacinth
culture system.

Temperature. The hyacinth is a tropical plant. This does not
preclude their seasonal culture in northern areas. Corn is also a
tropical species. Water temperature is a controlling factor in hyacinth
growth. Water temperature near the freezing point will result in death
of the plants. Francois (1977) determined hyacinth growth characteristics
at varying water temperatures in a phytotron. It was found that active
growth was restricted to the range of 10 to 35 C. Optimum growth was
obtained in the range from 25 to 27.5� C. Two days of exposure to a
water temperature of 450 C killed the plants.

Villamil, et al. (1979) obtained sustained production of near
108.2 kg/ha'd, or 39.5 MT/yr (dry weight) of hyacinth biomass in the
ideal climate of Puerto Rico. It should be pointed out that these
productivity measurements were based upon the vegative multiplication
of plants. It is believed that an even higher rate of production
might result if only plant stems and leaves were removed (mown) on a
periodic basis.

218

Continuous culture in open basins in Texas is feasible only in the
sub-tropical climate of the Lower Rio Grande Valley. Greenhouse protec-
tion will be required elsewhere. A single layer greenhouse cover will
probably suffice in most areas of Texas. Insulated, double layered
greenhouse covering may be needed in the Panhandle region. Raw sewage
temperatures are usually above 100 C even in cold regions in the abscence
of excessive infiltration into sewers. There is also the possibility of
installing solar collecting panels on properly oriented earthen berms
inside the greenhouse to enhance temperature conditions. Deep culture
basins (3-in) supplied with diffused aeration as proposed by Stewart, et
al. (1979) might be advantageous. A 0.4-ha aerated hyacinth treatment
system (open basin) receiving up to 1890 m3-d of raw and partially
treated wastewaters is to be placed into operation in the near future at
Port Arthur, Texas.

Residue Management. With one exception, continuous hyacinth
harvest is not being practiced in Texas. A single, annual harvest is
being suggested to remove dried plants and basin debris from culture
basins.

Sludge constitutes a greater proportion of basin debris than that
of plant biomass. Continuous harvest in small hyacinth treatment systems
serves to disrupt treatment. Open areas in the mat allows algal growth
and desirable biota are removed with the plants.

Application. Hyacinth culture may be used in almost any instance
where there is a need to improve organic, or mineral water quality.
Hyacinth culture can be used as a complete treatment process with
unscreened raw sewage being introduced directly into the culture unit.
Effluent quality from such a properly designed system may be expected to
equal, or exceed that obtainable by conventional secondary processes.

Seasonal hyacinth cultivation could be employed to remove excess
nutrients from small lakes. Water from the subject lake would be pumped
to a hyacinth culture unit and return by gravity flow. The culture
basin would be taken out of operation, drained, and the accumulated
debris removed at the end of each growing season.

Upgrading secondary wastewater treatment plant effluent quality,
biomonitoring, pre-treatment of raw water supplies, removal of specific
chemical compounds, and the demineralization of brackish waters are
other possible uses for hyacinth culture.

Concepts

Biological Dlemineralization. Many arid areas of the World are
underlain by aquifers whose waters are saline. Biological deminerali-
zation of brackish waters by hyacinth culture is an exciting possibility.

219

About 20 percent of dry hyacinth biomass is ash (minerals). Plants
grown in the Williamson Greek pilot system contained a mean chloride
content of 6.35 percent on a dry weight basis. Boyd (1970) reported a
chloride level of 5.95 percent (dry weight) in hyacinths. Parra and
Hortenstine (1974) determined the chemical composition of wild hyacinth
populations in Florida. Maximum dry weight percentages of elements
found were: Potassium - 6.5; calcium - 2.41; magnesium - 1.86; and
sodium - 1.54. Wolverton and McDonald (1976) recorded a 14 percent
decrease in total dissolved solids content of wastewaters treated in an
open hyacinth basin at Orange Grove, Mississippi.

Several million dollars would be required to construct and fully
evaluate an experimental prototype biological demineralization facility.
Should the concept prove feasible, subsequent systems would be quite
economical as most energy requirements would be met through the genera-
tion of methane from harvested hyacinths. A possible design of such a
facility would involve the provision of lined basins covered with greenhouses
having triple layers of clear plastic. Nutrient input could be livestock
wastes. Appropriate recirculation of effluent to dilute incoming flow
to a salinity level permitting hyacinth growth would be necessary.
Refrigerated air would pass through the inner layer of the cover to
enhance condensation of water vapor produced from evapotranspiration and
to reduce interior air temperature. Collected condensate would be
returned to the influent. Continuous hyacinth harvest would be practiced
and ammonia extracted from digestor supernatant would return to the
culture basins.

Crop Production. Hyacinths normally float upon a water surface.
They will grow equally well in moist, enriched soil as shown in Figure
14. The possibility exists to grow hyacinths as a field crop utilizing
flood irrigation. Conceptual design of a field crop production system
is presented in Figure 15. Production paddies would be drained and
allowed to dry somewhat prior to harvest. Plants could be mown period-
ically with light weight machines equipped with ballon tires. (This
would depend upon a favorable response of plants to cropping.)

Transport. Vehicular transport of fresh hyacinths is energy inten-
sive as 95 percent of the cargo consists of water. Transport of hyacinths
for short distances to methane generation digestors, or to livestock
feed processing facilities may possibly be accomplished via pipeline.
Sufficient water would be added to fine chopped plant material to form a
slurry which could be pumped through piping.

Aquatic Harvest. One approach to continual harvest of plant material
for nutrient removal without interfering with treatment efficiency
might be such a scheme as depicted in Figure 16. Land based harvest
equipment could be employed for mowing the plants. Leaves and stems
would represent a more desirable product for livestock feed than the
entire plants.

220

Fig. 14 Rooted Plants Growing in Moist
Soil Adjacent to a Hyacinth
Culture Basin, 1979.

(Courtesy of H. Nordmeyer)

221

FIG.1 5 CONCEPT - HYACINTH CROP PRODUCTION IN
IRRIGATED SHALLOW PADDIES

~~~~~~~~~~~~~~~~~~~MO

FINERv~u

FIG, 16 CONCEPT - HYDRAULIC ELEVATION OF
CHANNEL GROWN HYACINTH
TO FACILITATE MACHINE
HARVEST BY MOWING

ROAD BED

23E-HVEST

F~~~~~-~0,3-m DEPTH

[(~ ~ ( ROAD ED

~" ~l *''-- 1,2-M DEPTH

ROAD BED

*---- ,3-M DEPTH

223

CONCLUSITONS

1. Sufficient information is available for designing hyacinth
treatment facilities to be employed in warm climates.

2. Optimal design of culture basins is necessary to minimize
areal requirements and greenhouse costs in temperate climates.

3. Hydraulic loading is the most critical consideration in
culture basin design.

4. The primary pollutant removal mechanism of hyacinth treatment
is the reduction of suspended particulate content.

5. Harvest of hyacinths disrupts treatment. Provision of
multiple culture basins to allow alternate operation is
desirable. Each culture basin should be drained and the
accumulated sludge and plant debris removed on an annual
basis.

6. Hyacinth culture may be employed as a complete treatment
process.

7. Nitrogen management is a key factor in utilizing hyacinths
for wastewater treatment, or for biomass production. Stabilization
ponds can be designed for effective nitrogen reduction.
Hyacinth culture will remove most remaining nitrogen in pond
effluent, especially that which is in the organic form (algae).

8. Stabilization ponds followed by hyacinth culture constitutes
a highly effective wastewater treatment system.

9. A hyacinth treatment system is capable of producing effluent
having a mean content of <10 mg/l BOD 5 and TSS.

ACKNOWLEDGEMENTS

Our gratitude is extended to the City of Austin for facilities
provided for the pilot studies and the full-scale study underway at the
Williamson Creek wastewater treatment plant. Special thanks are given
to Mr. Herbert Nordmeyer, Enforcement Division, Texas Department of
Water Resources, for assembling data on hyacinth wastewater treatment
systems in the Rio Grande Valley and for photos provided. We also wish
to acknowledge the cooperation of officials of the Rio Grande Valley
Pollution Control Authority, the City of Rio Hondo, and the City of San
Benito.

.224

1. Boyd, C., 1970. Vascular Aquatic Plants for Mineral Nutrient Removal
from Polluted Waters. Economic Botany 24:95-103.

2. Dinges, R. 1979. Stabilization Ponds. Chapter in Manual of
Wastewater Operations, 5th edition, Texas Water Utilities
Association, Lancaster Press, Lancaster Pennsylvania (In Press).

3. Dinges, R. and Rust, A. 1970. The Ennis Study Experimental
Chlorination of Stabilization Pond Effluent. Report - Texas
Department of Health, Austin, Texas. pp. 117.

4. Dinges, R. 1973. Biological Demineralization of Water.
Report-(Unpublished) Texas Department of Health, Austin,
Texas. pp. 21.

5. Dinges, R. 1976. A Proposed Integrated Biological Wastewater
Treatment System. Chapter in Biological Control of Pollution.
Univ. of Pa. Press, Philadelphia, Pa. pp. 225-235.

6. Dinges R. 1976. Water Hyacinth Culture for Wastewater Treatment.
Report - Texas Department of Health, Austin, Texas. pp. 143.

7. Dinges, R. 1980. Natural Systems for Water Pollution Control.
Van Nostrand Reinhold, New York, N. Y. (In Manuscript).

8. Francois, J. 1977. Quelques Reactions Thermiques De La
Croissance Chez Eichhornia Crassipes (Mart.) Solms-Et Leur
Formulation. Analytique. Report - Univ. Catholique de Louvain,
Belgium. pp. 33.

9. Nuese, D. 1976. The Removal of Algae From an Oxidation Pond
Effluent Through the Use of a Tertiary Water Hyacinth Pond System.
MS Thesis, Texas Univ., Austin. pp. 62.

10. Parra, J. and Hortenstine, C. 1974. Plant Nutritional Content
of Some Florida Water Hyacinths and Response by Pearl Millet
to Incorporation of Water Hyacinth in Three Soil Types. Hyacinth
Control Jour. 8:42-44.

11. Smallhorst, D.F. 1963. The History of Oxidation Ponds in the
Southwest. Environ. Health (India). 5:70-75.

12. Stewart, W., Alsten, C., Serfling, S. and Mendola, D. 1979.
Pilot Studies of the Solar Aquacell Controlled Aquaculture
Process for Wastewater Reclamation, Paper presented at the
A.W.W.A. Conference on Wastewater Reuse. Washington. D.C.

225

13. Villamil, J., Clements, R., Block, McB., Weil, P., Garcia, G.,
Lao, W., Rosa, L. and Santos, F. 1979. Water Hyacinths for
the Clarification of Wastewaters and the Production of Energy.
Report - Center For Energy and Environment Research, Univ. of
Puerto Rico., San Juan, P.R. pp. 30.

14. Wolverton, B. and McDonald, R. 1976. Water Hyacinths for
Upgrading Sewage Lagoons to Meet Advanced Wastewater Treatment
Standards: Part II. NASA Tech. Memo. TMOX-72730. Bay St.
Louis, Miss. pp. 13.

15. Wooten, J. and Dodd, J. 1976. Growth of Water Hyacinth
in Treated Sewage Effluent. Economic Botany, 30:29-37.

226

*APPENDIX*

227

TEXAS DEPARTM4ENT OF HEALTH

RECOMMENDATIONS FOR THE CONSTRUCTION AND
OPERATION OF HYACINTH BASINS FOR
UPGRADING STABILIZATION POND EFFLUENT

May 4, 1979

These recommendations are subject to modification as
more information on operating systems becomes available

DES IGN

1. Basin Sizing - Hyacinth basins should be sized for a maximum
surface loading rate of 0.2 mgd/acre with a mean water depth
of three feet. A maximum basin size of one acre is recommended.

2. Basin Configuration - Rectangular basins having a length to
width ratio of at least 3:1 would be preferable. Basins should
be designed to approach plug-flow conditions. Influent should
be introduced at intervals along the upper margin of the basin.
This may be accomplished via a perforated pipe having a minimum
diameter of 10 inches. Perforations should be spaced at a maximum
distance of 10 feet apart and be at least two inches in diameter.
Increased efficiency may be attained by dividing a rectangular
basin into equal parts by a diagonal, low earthen dike. Influent
would be distributed along the base of one right triangle,
collected at the apex, and reintroduced along the base of the
other triangle.

3. Basin Construction - Basins should be constructed by excavating
and diking the required area. Exterior dikes should have a
top width of ten feet and sides with a vertical to horizontal
slope of 1:3. Minimum freeboard should be two feet. An access
ramp must be provided with a width of at least 10 feet. Basins
should be designed for rapid arainage. The bottom of a culture
unit would be smooth and slope at least 0.5 percent from the upper
to lower end of the basin. A sump should be excavated at the
lower end of a culture unit to facilitate removal of residual
waters by draining or pumping back to the stabilization pond.

4. Dual Systems - Duplicate systems, each having a capacity to treat
the permitted average daily flow of the facility, must be provided.
Constant inflow, controlled by a valved pipe, should be maintained
to a culture basin. The feeder stabilization pond should serve
for flow equalization with the water level being allowed to
fluctuate. An appropriate transfer structure should be provided
to permit only surface stabilization pond waters to enter a
hyacinth culture basin.

229

5. Basin Piping - Piping should be installed in such a manner as to
allow parallel, or series operation of the culture basins. Basins
should be interconnected at the lower ends by a valved pipe having
a minimum diameter of 10 inches. A valved drain pipe must be
provided in each basin and laid on a level with the bottom of the
excavated sump near the basin outlet.

6. Barrier - A fixed barrier creating a clear zone of approximately
1.0% of the basin surface area must be installed around the outlet
to retain the hyacinth plants, allow for reaeration, and prevent
the discharge of plant debris. While screen may be used as a
barrier material, a permeable crushed rock or gravel dike is
preferred. If screens are used at least two must be provided with
the outer screen having a mesh size of not more than one inch and
the inner screen having a mesh size of not more than 1/4 inch. An
outlet box with an adjustable flow measuring weir must be provided
and located in the clear zone.

7. Mosquito Control - Galvanized wire mesh exclosures eight to ten
feet in diameter and at least four feet in height should be placed
at intervals throughout a basin to furnish clear areas to enhance
fish production for mosquito control.

8. Fencing - The hyacinth basins must be enclosed by a man-proof
fence with a locked gate.

9. Depth Control - A gauge should be provided to indicate water
depth in a hyacinth basin.

OPERATION

1. Continuous Operation - In areas where hyacinths may be grown
year-round, the basins may be operated on a continuous basis with
each basin receiving one-half the average daily wastewater flow.
Once each year the basins should be cleaned by diverting all the
was tewater through one basin while dewatering and removing hyacinth
plants and sludge from the other basin. The cleaned basin should
then be refilled via the interconnected piping with effluent from
the full basin and restocked with hyacinth plants.

2. Seasonal Operation - In colder regions only seasonal operation
will be permitted since the hyacinth plants freeze at a temperature
less than 32F with a resulting decrease in treatment efficiency.
At the time when plants are frozen or a decrease in effluent water
quality is noted the culture basin should be drained immediately,
allowed to dry and cleaned. Wastewater must be stored or treated
in some other approved manner during this period if it is not of
sufficient quality to meet Texas Department of Water Resources
permit requirements. The standby alternate basin may be filled and
planted when the danger of frost is over.

230

3. Cleaning - Draining of a hyacinth basin is initiated by closing
the influent valve and opening the drain valve. Rainwaters collecting
in the drain sump during the drying period should be removed quickly
by pumping into the stabilization pond. The basin should be cleaned
thoroughly using appropriate equipment. Dried plants and sludge
removed from a basin may be landfilled, converted into compost for
use in parks or nurseries, or used for soil amendment of agricultural
land used for grazing, or the production of grain and fiber crops.
Care should be excercised in handling materials removed from culture
basins to assure that it does not gain access to public waters.

4. Records - Sampling - Careful records should be maintained on the
water depth, flow rate and other operating parameters of the
system. It would be desirable to sample the raw wastewaters and
influent-effluent of the hyacinth basin on a weekly basis.

5. Mosquito Control - Hyacinth basins should be stocked with Gambusia
(mosquite fish-pot bellied minnows-top water minnows) to assure
that mosquito production is supressed. Other species which may be
stocked to supplement mosquito fish are Poecilia (green sailfin
mollies) and Astyanax (Texas tetra-Rio Grande jumping minnow-mud
minnow).

231

A WATER HYACINTH ADVANCED WAS TEWATER TREATMENT SYSTEM

Dan Swett, Development Research Manager, Coral
Ridge Properties, Coral Springs, Florida

A one year field experiment at the 378,530 lpd (100,000 gpd)
level has demonstrated that a system of 5,035 in2 5420ft)o
water hyacinth (Eichornia crassipes) lagoons can provide advanced
treatment to effluent from an activated sludge plant by achieving
removal rates of 67% for total suspended solids, 98% for biochemical
oxygen demand, 97% for total nitrogen and 79% for total phosphorus.
Biomass produced by the system offers a potential for energy,
fertilizer or fodder production.

PROJECT DEVELOPMENT

Coral Springs, Florida, is a "New Town" developed by Coral
Ridge Properties, a wholly owned subsidiary of Westinghouse Electric
Corporation, located in the northwestern portion of Broward County.
With a current population of 30,000, Coral Springs is adding
population and dwelling units at a rate of 7.5% per year making it
the fastest growing municipality in the Fort Lauderdale urban complex.
Almost all of the current growth and development is occurring
in the southern portion of the city where water, sewer and waste-
water treatment services are provided by the Coral Springs Improve-
ment District, a special taxing body created by act of the state
legislature. The District's wastewater treatment plant has a design
capacity of 7.6 mid, that will ultimately be expanded to 20.6 mild.
Method of treatment is by activated sludge, with effluent disposal
into a closed seepage lagoon.
Although the treatment plant produces a secondary effluent that
meets current state and county standards, the Broward County
Commission has adopted an ordinance requiring that, as of January 1,
1980, all non-ocean effluent discharges meet the advanced wastewater
treatment standards of 5 mg/l total suspended solids, 5 mg/l BOD5,
3 mg/i total nitrogen and I mg/l total phosporus.
This situation is further complicated by the fact that Broward
County is committed to the regional treatment system concept and has
received an EPA grant for installation of such a system. The Coral
Springs Improvement District has been asked by the county to join

233

the regional system as soon as sufficient capacity becomes available,
which is expected to occur sometime between 1983 and 1985. Some
portions of this system are in place, others under construction, and
others still in the planning stage.
The District is thus faced with the necessity of upgrading its
existing secondary treatment system to meet AWT standards by 1980.
Under normal circumstances, installation of conventional AWT facili-
ties with twenty year amortization would impose a large financial
burden on the District. This burden would be rendered totally in-
tolerable should the new facilities have to be abandoned within three
to five years upon integration of the District into the Broward
County regional wastewater treatment system. Project Hyacinth
represents an effort by Coral Ridge Properties to find a low-cost
way out of this dilemma for the Coral Springs Improvement District.
Funded entirely by Coral Ridge Properties, Project Hyacinth
was designed by Gee and Jenson, the District's consulting engineers,
to bring 378,530 lpd (100,000 gpd) of the treatment plant effluent
to AWT standards. Constructed on 0.93 hectares (2.31 acres) of
District-owned land, the system consists of a series of five ponds
with a total water surface area of 0.5 hectares (1.25 acres) (Fig. 1).
Design treatment time at the 378,530 lpd capacity is two days in
Pond A and one day in each of Ponds B through C, for a total of six
days. Water depth throughout the system is 38.1 cm (1.25 feet). An
impermeable asphalt seal on sides and bottoms of the ponds prevents
seepage loss (Table 1). Total construction cost of the system was
less than $65,000. On completion of construction, ponds were filled
with effluent and "seeded" with approximately 7.64 m3 (10 yds.3) of
water hyacinth plants (Eichornia crassipes) per pond. This was
accomplished on January 27, 1978.
Increase in the plant biomass was slower than anticipated, due
primarily to excessive chlorination of the effluent at the treatment
plant. When this condition was corrected and chlorine residual of
influent into the system reduced to approximately 1 mg/I, plant bio-
mass increased rapidly. Some harvesting was accomplished during the
biomass increase period to remove dead and malnourished plants.

SPLIT FLOW OPERATION

Data collection began May 15, 1978, with 90% coverage in all ponds.
The project sampling plan called for simultaneous 24-hour composite
sampling at the Pond A influent point and the Pond E effluent point
to establish levels of analytical variables achieved by treatment in
the full system at the design time of six days, and thereafter move-
ment of sampling forward to outflow points of Ponds D, C and B to
establish levels achieved by curtailing treatment time to five, four
and three days. This plan was adhered to through November, 1978,
except that effective June 13, composite sampling time was increased
to 48 hours, halving the number of samples to be analyzed each month.
Metering of influent and effluent flows established a high evapo-
transpiration loss, amounting to 16.24 x 10 lpd (42,900 gpd) or
32.35 lpd/m (0.7915 gpd/ft2) of water surface. This loss appears

234

constant due to the high liquid uptake of the plants and therefore
is unaffected by flow into the system.
In December, 1978, because surge overloads at the treatment
plant were causing high solids inflows into the system, the sampling
plan was amended to include grab sampling every other day at the
outflow point of each pond to trace progress of solids and nutrients
through the system. This grab sampling revealed a consistent drop
in levels of analytical variables between the influent point and the
Pond A outflow point, then an increase in these variables at the
Pond B outflow point, followed by decreases at the outflow points
of Ponds C, D and E. To insure that the increase in analytical
variable levels from Pond A to Pond B was not related to the time
of grab sampling, four additional composite samplers were placed in
operation on February 1, 1979, and 48 hour composite samples drawn
from the Pond A influent point and the effluent point in each pond.
This composite sampling verified that concentrations Of an-
alytical variables increased in Pond B and decreased thereafter.
Removal of hyacinth plants from the inflow end of Pond B revealed
that influent was entering the pond from two points -- from Pond A
and also directly from the treatment plant influent line. On
investigation, valves installed to permit shunting of influent flow
into either Pond A or Pond B we-re both found to be open, resulting
in simultaneous flow into both Ponds. Closure of the valve to
Pond B restored the system to its original operational plan on
February 28, 1979.
Simultaneous 48 hour composite sampling at the Pond A influent
point and at the outflow point of each pond was continued. Engineer-
ing calculations established that during the period May 15, 1978 -
February 28, 1979, the divided influent flow resulted in 45% going
into Pond A and 55% into Pond B. An equation was formulated to
enable calculation of total flow into Pond B, consisting of outflow
from Pond A (inflow into Pond A less evapo-transpiration loss plus
flow into Pond B directly from the treatment plant). A second
equation was formulated to calculate the combined concentration of
analytical variables entering Pond B as a result of the combined
inflow from Pond A and from the treatment plant (appendix).
Adjusted influent loadings into Pond B during the split flow
period for liters per day, total nitrogen and total phosphorus are
shown in Table 2. Because effect of the split flow on total suspended
solids and BOD5 was neglibible, no adjustment of these variables was
made.
Results of the hyacinth treatment, based on the system of Ponds
B through E, are shown in Table 3. Treatment times shown in this
table are based on total loadings into Pond B and are adjusted for
evapo-transpiration loss in each pond. All grab samples from Ponds
C and D during January were taken at the peak flow time of 9:30
to 10:00 a.m.

UNITARY FLOW OPERATION

Flow into Pond A only was restored on February 28, 1979, and

235

data collection during the period March I - May 31, 1979, was
accomplished by 48 hour composite sampling at the Pond A influent
point and at the outflow point of each pond. Influent flow was
maintained at 435,102 lpd (115,000 gpd) throughout, except for 48
hours in April and 12 hours in May when flows were reduced to zero.
Knowledge gained from the previous nine months of experimental
operation was used to operate the system for maximum efficiency.
During the period, nitrogen removal rates ranged from 62% to
96%, and phosphorus removal rates ranged from 18% to 60%. Reduc-
tions in mass loadings for these two variables, adjusted for evapo-
transpiration loss, and removal rates achieved according to treat-
ment time are contained in Tables 4 and 5.
Treatment plant operations during the months of April and May
were erratic due to construction activities and were reflected in
abnormal variability of pollutant concentrations in influent into
the hyacinth system. On April 17, construction was completed on
3,785,300 lpd (I mgd) of new treatment plant capacity and inflow
into the hyacinth system was completely shut off for 48 hours to
enable rapid filling of the new tanks. Problems with the new plant
operation necessitated its shutdown on April 19 for debugging, with
restoration of flow into the hyacinth system, as which time transfer
back to the old plant resulted in a heavy inflow of untreated solids
into the hyacinth system.
On April 25, unusual weather conditions dumped 36.8 cm (14.5
inches) of rain on the area in less than 24 hours. This rainstorm,
calculated as having a probability of occurrence of less than once
in 200 years, created temporary flood conditions that again caused
plant operational problems and heavy inflows of untreated solids
into the hyacinth system for 48 hours. Despite these two treatment
upsets, the only effect on the hyacinth system was the onset of
chlorosis in plants in Pond E, caused by undernourishment resulting
from the two day shutdown of flow into the system.
During May, efforts to restore normal treatment in the plant
caused pollutant concentrations in the influent into the hyacinth
system to rise steadily from the first of the month, culminating in
highs of 22 mg/l total suspended solids, 110 mg/l BOD, 132.29 mg/l
total nitrogen and 44.52 mg/l total phosphorus on the 21st. In
addition, influent flow into the system was shut down from 10:00 p.m.
on the 22nd to 10:00 a.m. on the 23rd.
It is noteworthy that during the period of the heaviest pollutant
concentration inflow, the hyacinth system demonstrated the highest
degree of efficiency in nutrient removal, apparently as a result of
increase in the N:P ratio. When the N:P ratio was at its highest,
2.97:1, on May 21, total nitrogen and total phosphorus concentrations
at the Pond C outflow point were 0.86 and 0.87 mgJI, respectively,
on May 26th and 0.74 and 0.71 mg/l on May 28th. This indicates
that the most effective nutrient removal occurs when the influent
N:P ratio is approximately 3:1.
Influent loadings into the system and analytical variable con-
centrations at the outflow point of each pond for the March I
May 31 period are contained in Table 6. Extremely high variability
in loading concentrations of each variable during May are shown by
the standard deviations. These concentrations were reduced to almost

236

negligible amounts as they flowed through the system. Because
the overall effect of any effluent discharge is more a function
of the total amount of each pollutant contained in the effluent
than the concentration thereof, it is worthwhile to consider total
contents of each variable on a mass loading basis at the hyacinth
system influent point and at the outflow point of each pond. Table
7 presents these data for the period March I - May 31, 1979, based
on daily flow into the system and adjusted for evapo-transpiration
loss in each pond.

CONCLUSIONS

Because achievement of nitrogen removal is the most difficult
and expensive aspect of conventional advanced wastewater treatment
processes, treatment time required by a hyacinth system to achieve
any desired concentration of total nitrogen in final effluent is a
crucial planning factor. The scattergram (Figure 2) portrays the
actual relationships between treatment times and total nitrogen
concentrations achieved by Proj ect Hyacinth (grab sampling data not
included). Analysis of the total nitrogen-treatment time relation-
ship by linear regression enables use of the least squares equation
to predict the treatment time required to achieve any desired con-
centration of total nitrogen.

Data contained in Table 6 yields the least squares prediction
equation:

Y = 3.91 + (-0.65)X,

in which Y = mg/l total nitrogen and X = days' treatment time.
Correlation coefficient for the equation is -0.60. By this predic-
tion equation, for a Y value of 3.00 mg/l nitrogen, 1.4 days treat-
ment is required over a system with I m2 of water surface per 86 lpd
effluent. Standard deviation of the predicted Y at this level of
X is 1.34, thus to achieve the indicated confidence levels, treat-
ment times as follows would be required:

Confidence Level Days' Treatment
99% 4.95
97.5% 4.3
95% 3.77
90% 3.21

Experience gained during the year of Project Hyacinth operation
indicates that, while the system can successfully cope with a
variety of stresses, health of the plants must be maintained for
most effective treatment. While the water hyacinth is a hardy,
disease-resistant plant that thrives at all above freezing tempera-
tures, its growth rate and nutrient uptake efficiency can be com-
promised.
Presence of a high chlorine residual definitely inhibits plant
growth. If possible, effluent chlorination should be accomplished

237

subsequent to hyacinth treatment. If local conditions dictate pre-
hyacinth chlorination, care should be taken that chlorine residual
in the influent does not exceed I mg/I. Plant health is also
adversely affected by chlorides. Early in the project's operation
189 liters (50 gallons) of a 40,000 mg/I NaCl solution were injected
at the influent point in an effort to trace progress of the solution
through the system by continuous conductivity readings. Three days
of readings along the length of Pond A showed no chloride presence,
indicating total uptake of the solution by the plants. Three days
later, plants in a fifteen foot wide strip down the middle of Pond A
exhibited severe chlorosis (leaf yellowing).
Maintenance of nourishment is essential to plant health.
Hyacinth has a voracious appetite, which if not satisfied also results
in chlorosis and decreased uptake efficiency. Least efficient per-
formance of the system was obtained during periods of significantly
reduced influent flow and during periods when influent nitrogen con-
centration dropped below 10 mg/I. Plant health is also adversely
affected by overcrowding. During July and August, 1978, no plants
were harvested for a period of more than six weeks to determine
effect of overcrowding. Chlorosis began to appear after four weeks
and increased in severity rapidly, accompanied by a decrease in up-
take efficiency.
The best indication of plant health is an abundant growth of
dark green leaves. Any appearance of stunted leaf growth with
yellowish green leaves in immature plants or of leaf yellowing in
mature plants should be investigated immediately.
Intense sun with temperatures in the mid-nineties may cause some
leaf browning and wilting. This is not a serious condition if new
growth is present, beneath the brown wilted leaves. Wilted-leaved
plants may be removed during the normal harvest cycle by selective
harvesting.
Healthiest plant condition and best system performance was ob-
tained when ponds were maintained in a loosely packed condition by
a four week harvest cycle. From 15 to 20% of the plants should be
removed at each harvest. Uncovering more than 20% of pond surface
area will result in an algae problem. Harvest biomass on the four
week cycle averaged 137.6 m2 (180 yds3), or I m3/36.6 m2 of pond
surface.
During the year of Project Hyacinth operation, the biomass
growth rate appeared totally unaffected by seasonal temperature
variations. Fahrenheit temperatures ranged from the mid-thirties
to low seventies during January and February, from the forties to
low eighties in the spring and fall, and from the upper seventies
to upper nineties during the summer months.
When Project Hyacinth was designed, it had been planned to
harvest with a weed bucket-equipped front-end loader. This proved
impractical because the 38.1 cm water depth affected the front-end
loader's hydraulic system. A Gradall was used for two harvests but
was discontinued because hydraulic fluid from the boom dripped into
the ponds, and also because of its high cost. The best performing
harvesting equipment was a weed-bucket equipped, truck-mounted drag-
line. This equipment, with a dump truck, was able to accomplish a

238

normal harvest in six to seven hours. Had the ponds been fifteen
feet narrower, dragline harvesting efficiency would have been imn-
proved considerably.
Throughout Project Hyacinth, persistent clogging of the
influent flow meter made accurate determination of influent flow
rates difficult. Occasional shut-off, both intended and non-intend-
ed, of influent flow also caused serious problems. In a full-
scale system, reliable influent and effluent f low metering and an
influent flow system not subject to shut-off or clogging would be
essential.
In Project Hyacinth, harvested plants were placed on a con-
crete drying pad between Ponds A and E, draining into Pond A. Two
to three weeks' drying resulted in a 75% volumetric reduction in
the biomass. The dried biomass was removed to a tree nursery and
composted. It proved to be a superior fertilizer.
Project Hyacinth has proven that a 0.4 hectare/378,530 lpd
(one acre/100,000 gpd) water hyacinth treatment system is capable
of bringing secondary wastewater effluent to AWT standards for total
suspended solids, BOD5 and total nitrogen in three to five days,
depending on confidence level required. Further investigation is
underway to determine if the influent N:P ratio can be increased
sufficiently by ammonia addition to achieve sufficient phosphorus
uptake to meet the AWT standard for this element. If so, it must
also be determined if such ammonia addition is cost-effective
compared to chemical precipitation for phosphorus removal.
At any rate, there appears to be no doubt that even with
addition of chemical phosphorus removal, a water hyacinth AWT system
can be much more cost-effective in both capital and operations and
maintenance costs than a conventional AWT system.
Given the present state of the art, for small sun-belt
communities, in which freezing temperatures are of very short
duration and land is available,, water hyacinth treatment now pro-
vides an excellent low cost means of bringing small activated sludge
plant effluent flows (400,000 lpd or less) to AWT standards. For
larger communities with effluent flows in excess of 400,000 1pd,
disposition of the harvested hyacinth biomass may require a by-
production process. Depending on local geographic and economic
considerations, the harvested biomass may be used for energy,
fertilizer or fodder production. Additional field research is
required in these areas.

239

Appendix

1. Adjustment equation for influent flow split between Ponds A
and B:

QB = Q - EA

where Q = total flow into system, lpd,
QB = flow into Pond B, lpd, and
EA = evapo-transpiration loss in Pond A, lpd.

2. Adjustment equation for concentration of any variable entering
Pond B as result of split influent flow:

CBi = 0.55QCi + (0.45Q-EA) CAe
QB
where Q, QB and EA are as in Equation 1, and
Ci = concentration in influent into system, mgll,
CBi = concentration entering Pond B, mg/l, and
CAe = concentration leaving Pond A, mg/l.

3. Adjustment equations for treatment time:
a. Pond A, Split influent Flow:

TA= 2 VA
Q(0.45) + (Q(O.45)-EA)

where Q and EA are as in Equation 1,
TA = Time in Pond A, days, and
VA = Volume of Pond A, liters.

b. Pond A, Unitary Flow:

TA 2 VA
Q + (Q-EA)

c. Ponds B through E:

2VB.....E
TB ..E = QiB..... E + QoB.....E

where B .....E = Time in designated pond, days,
VB .....E = Volume of designated pond, liters,
QiB .... E = Inflow into designated pond from preceding
pond, lpd,
QOB ....E = Outflow from designated pond; i.e., inflow from
preceding pond minus evapo-transpiration loss
in designated pond.

240

d. Adjusted system treatment time:

Ts = TA + TB ...... TE

where Ts = Time in system, days.

4. Table of volumes and evapo-transpiration losses:

Volume Evapo-Transpiration Cumulative Loss
Pond (liters) Loss (lpd) (lpd)
A 645,772 58,369 58,369
B 282,761 26,005 84,374
C 282,761 26,005 110,379
D 282,761 26,005 136,384
E 282,761 26,005 162,389

241

Table 1
Project Hyacinth Design Data

Pond A Ponds B-E ea. Total System
Dimensions
(Inside) 26.82 m x 83.82 m 26.82 m x 39.62 m 61.87 m x 131.67 m
Water
Surface
Area 1,810 m 806 m2 5,035 m
Water
Capacity 645,772 1 282,762 1 1,776,820 1
Treatment
Time at
378,530
lpd 2 days 1 day 6 days

Influent to Pond A; through 7.62 cm (3 inch) i.d. pipe

Pond connecting pipes: 30.5 cm (12 inch) i.d.

Berms: 4.57 m (15 feet) between ponds, 1.83 m (6 feet) outside
of ponds.

Effluent from Pond E: Outflow over 90� V-notch wier, 15.2 cm
(6 inch) deep. Maximum capacity, 730.6 lpm (193 gpm).

Meters:

Influent - Badger model MLFT-SGH 7.6 cm (3 inch) propeller meter.

Effluent - Leupoldt Stevens model 61R flow recorder.

242

Table 2
Pond B
Adjusted Influent Loadings

TSS* BOD5* Total N Total P
Dates LPD Mean Std. Dev. Mean Std. Dev. Mean Std. Dev. Mean Std. Dev.
mg/l mg/l mg/l mg/l mg/l mg/1 mg/l mg/l

5/15-6/5/78 3.2 x 105 6.40 4.18 5.81 1.29 7.78 1.90 5.55 1.57

6/13-7/31/78 2.33 x 105 5.80 5.60 8.33 8.81 7.47 1.45 5.18 1.36

8/1-31/78 2.32 x 105 2.80 0.99 3.25 0.43 8.08 2.46 5.51 1.18

9/1-30/78 3.45 x 105 2.87 0.62 2.67 0.47 6.58 1.33 5.93 1.47

10/1-31/78 3.0 x 105 2.43 0.49 3.00 0.70 7.68 1.03 6.29 1.10

11/1-30/78 3.28 x 105 -- -- -- -- 8.96 1.24 4.74 1.28

12/1-31/78 3.54 x 105 16.33 21.07 7.75 2.69 9.84 1.47 6.72 1.29

1/1-31/79 3.77 x 105 7.20 3.71 4.25 0.43 9.39 1.82 5.88 0.49

2/1-28/79 3.77 x 105 3.93 1.10 4.25 0.43 7.81 1.17 4.99 1.48

* Unadjusted Loading

Table 3
Pond C Effluent
TSS BOD5 Total N Total P
Adj. Treatment Mean Std. Dev. Mean Std. Dev. Mean Std. Dev. Mean Std. Dev.
Dates Time (Days) mg/l mg/l mg/ mgl mg/ l mg/g mg/ mg/l

9/1-30-78 2.27 3.80 0.65 3.22 1.15 5.31 0.53

10/1-31/78 2.33 3.75 0.43 3.90 0.91 6.00 0.34

11/1-30/78 2.10 -- -- 5.10 2.34 4.39 0.85

12/1-31/78 2.10 -- -- 6.13 1.47 4.12 0.63

1/1-31/79* 1.93 4.33 0.87 4.71 1.21 5.53 0.36

2/1-28/79 1.93 3.71 0.79 3.43 1.19 4.75 0.11

Pond D Effluent

8/1-31/78 6.43 4.07 1.29 3.67 0.94 1.00 0.37 4.95 0.96

10/1-31/78 4.21 -- -- -- -- 1.85 0.54 -- --

11/1-30/78 3.71 3.60 1.36 -- -- 2.53 1.09 4.03 0.74

12/1-31/78 3.33 5.16 0.90 -- -- 4.00 1.15 4.33 0.43

1/1-31/79* 3.04 4.13 1.36 -- -- 3.39 1.52 5.19 0.50

2/1-28/79 3.04 3.21 0.56 -- -- 2.20 0.90 4.61 0.39

Pond E Effluent

TSS BOD5 Total N Total P
Adj. Treatment Mean Std. Dev. Mean Std. Dev. Mean Std. Dev. Mean Std. Dev.
Dates Time (Days) mg/l mg/i mg/l mg/l mg/l mg/1 mg/l mg/i

5/15-6/5/78 5.51 3.77 1.42 3.90 0.88 0.66 0.18 3.65 0.89

6/13-7/31/78 9.83 3.28 1.30 3.83 0.69 0.53 0.14 3.74 0.56

10/1-31/78 6.09 3.17 0.69 3.33 1.50 1.57 0.54 5.37 0.82

11/1-30/78 5.30 3.71 0.88 -- -- 1.66 0.76 4.43 0.43

12/1-31/78 4.70 2.67 0.94 3.33 0.47 1.64 0.63 5.49 0.10

1/1-31/79 4.30 3.20 0.70 3.25 0.43 2.56 0.72 5.26 0.47

2/1-28/79 4.30 3.07 0.59 3.00 0.71 1.52 0.68 4.32 0.58

* Grab sampling

Table 4
Nitrogen Concentrations, Mass Loadings & Removal Rates*
5/15/78 - 2/28/79

Influent Treatment Effluent
Time
Concentration Mass Load days Concentration Mass Load Removal
mg/l kg/day mg/l kg/day Rate (%)

7.78 2.49 5.51 0.66 0.14 94

7.47 1.74 9.83 0.53 0.07 96

8.08 1.87 6.43 1.00 0.15 92

6.58 2.27 2.27 3.22 0.94 58

7.68 2.31 6.09 1.57 0.31 87

8.96 2.94 5.30 1.66 0.37 87

9.84 3.48 4.70 1.64 0.41 88

9.39 3.54 4.30 2.56 0.70 80

7.81 2.94 1.93 3.43 1.11 62

7.81 2.94 3.04 2.20 0.66 77

7.81 2.94 4.30 1.52 0.41 86

* Adjusted for Evapo-transpiration Loss

Table 5
Phosphorus Concentrations, Mass Loadings & Removal Rates*
5/15/78 - 2/28/79

Influent Treatment Effluent
Time
Concentration Mass Load days Concentration Mass Load Removal
mg/l kg/day mg/l kg/day Rate (%)

5.55 1.78 5.51 3.65 0.79 56

5.18 1.20 9.83 3.74 0.48 60

5.51 1.28 6.43 4.95 0.76 41

5.93 2.05 2.27 5.31 1.56 24

6.29 1.89 6.09 5.37 1.05 44

4.74 1.55 5.30 4.43 0.99 36

6.72 2.38 4.70 5.49 1.37 42

5.88 2.22 4.30 5.26 1.44 35

4.99 1.88 1.93 4.75 1.54 18

4.99 1.88 3.04 4.61 1.38 27

4.99 1.88 4.30 4.32 1.18 37

* Adjusted for Evapo-transpiration Loss

Table 6
Pond A Influent
Loading Rate: 435,102 lpd

TSS BOD5 Total N Total P
Month Mean Std. Dev. Mean Std. Dev. Mean Std. Dev. Mean Std. Dev.
1979 mg/l mg/1 mg/l mg/l mg/l mg/1 mg/1 mg/1

March 3.33 0.79 3.50 0.50 10.12 1.34 6.12 1.46

April 4.27 3.21 3.00 0.71 5.75 2.14 5.03 1.38

May 9.33 4.75 8.73 44.60 42.74 35.16 20.08 12.26

March-May 5.64 4.22 13.08 29.27 22.41 25.27 10.95 9.35

Pond A Effluent
Adjusted Treatment Time: 1.59 Days

March 3.20 0.92 -- -- 3.71 1.35 5.11 1.06

April 3.33 1.19 -- -- 5.75 2.14 5.03 1.38

May 4.00 0.63 -- -- 0.89 0.23 3.50 0.99

March-May 3.51 0.81 -- -- 3.51 2.47 4.55 1.17

Pond B Effluent
Adjusted Treatment Time: 2.37 Days

TSS BOD5 Total N Total P
Month Mean Std. Dev. Mean Std. Dev. Mean Std. Dev. Mean Std. Dev.
1979 mg/l mg/l mg/i mg/i mg/i mg/l mg/l mg/l

March 3.20 0.83 -- -- 2.18 1.14 4.57 0.77

April 3.20 0.65 -- -- 3.08 1.98 4.61 1.13

May 4.13 0.62 -- 0.89 0.22 2.28 0.70

March-May 3.51 0.83 -- -- 2.05 1.60 3.82 1.23

Pond C Effluent
Adjusted Treatment Time: 3.21 Days

March 3.13 0.80 -- -- 1.49 0.76 4.24 0.74

April 3.87 0.80 -- -- 1.71 0.95 4.28 0.84

May 4.47 0.52 -- -- 0.74 0.14 2.01 0.88

March-May 3.82 0.92 -- -- 1.31 0.82 3.49 1.35

Pond D Effluent
Adjusted Treatment Time: 4.12 Days

TSS BOD Total N Total P
Month Mean Std. Dev. Mean Std. Dev. Mean Std. Dev. Mean Std. Dev.
1979 mg/1 mg/l mg/i mg/l mg/l mg/l mg/l mg/l

March 2.71 0.80 1.13 0.47 3.92 0.71

April 4.00 0.89 -- -- 1.30 0.54 4.28 0.78

May 3.47 0.50 -- -- 0.76 0.12 2.09 0.80

March-May 3.41 0.99 -- -- 1.01 0.48 3.41 1.40

Pond E Effluent
Adjusted Treatment Time: 5.11 Days

March 2.90 0.54 2.50 0.50 0.94 0.26 3.77 0.65

April 2.87 0.50 2.50 0.50 1.24 0.55 4.49 0.75

May 3.20 0.54 3.75 0.43 0.82 0.25 2.56 0.45

March-May 2.95 0.81 2.92 0.76 1.00 0.42 3.60 1.01

Table 7
Total Loadings and Total Effluent Content & Removal Rates
March 1 - May 31, 1979

TSS BOD5 Total N Total P
Removal Removal Removal Removal
Sampling Rate Rate Rate Rate Adj. Treatment
Point kg/day % kg/day % kg/day % kg/day % Time (Days)

Influent 2.45 -- 56.62 -- 9.75 -- 4.77 -- --

Pond A
Outflow 1.32 46 -- -- 1.32 43 1.71 64 1.59

Pond B
Outflow 1.23 50 -- -- 0.72 93 1.34 72 2.37

Pond C
Outflow 1.24 43 -- -- 0.42 96 1.13 76 3.21

Pond D
Outflow 1.02 58 -- -- 0.30 97 1.02 79 4.12

Pond E
Outflow 0.80 67 0.85 98 0.27 97 0.98 79 5.11

Figure 1
Hyacinth System Schematic

Pond Pond
'E' 'D'

Pond
'C'

Pond

Pond
Is'

252

Water hyacinth covered ponds
operated by the Coral Springs
Improvement District.

6/14/78

Harvesting water hyacinths with
a weed-bucket equipped, truck
mounted drag line.

Water hyacinths being placed on
a concrete solar drying pad.

Figur e 2

SCATTERGRAM
V
Total N
(Mg/I)

0*I ~~~~~4

0~~~~~59 1
3~~~~~~~~~~~~~~ ~Tm C Dys

Acknowledgments

Dr. B. C. Wolverton, National Space Technology Center, Bay
St. Louis, Miss., whose pioneering work in water hyacinth waste-
water treatment led to the inception of Project Hyacinth, for
his guidance and suggestions.

Dr. William Duff er, Robert Kerr Environmental Research
Laboratory, Ada, Oklahoma, for his interest, guidance and
suggestions.

Dr. Ronald F. Lewis, Municipal Environmental Research Laboratory,
E.P.A., Cincinnati, Ohio for his interest and suggestions.

Dr. Thomas deS. Furman, et al.., Department of Engineering
Science, University of Florida, Gainesville, Florida, whose studies
of nutrient removal by water hyacinth provided data for engineering
design of Project Hyacinth.

255

WATER HYACINTH WASTEWATER TREATMENT SYSTEM
AT WALT DISNEY WORLD

Andrew P. Kruzic, Reedy Creek Utilities Company,
P.O. Box 40, Lake Buena Vista, Florida 32830

INTRODUCT ION

Pioneering scientific studies sponsored by the National Aero-
nautics and Space Administration and performed by the National Space
Technology Laboratories at Bay St. Louis, Mississippi, have shown that
vascular aquatic plants, such as the water hyacinth (Eichhornia
crassipes), can be remarkably effective in the removal of nutrients
and toxic materials from municipal and industrial sewage. The potential
for utilization in both secondary and tertiary wastewater treatment
systems has been demonstrated (ref s. 1 and 2). In addition, the
prospects for developing useful products from the harvested plant are
promising (ref. 3). Although these studies have demonstrated feasibi-
lity, the ultimate commercialization of a water hyacinth wastewater
treatment system requires its comparative evaluation with alternative
wastewater treatment systems, both economically and with regard to
typical water quality standards and requirements.

'A study performed by the Battelle Columbus Laboratories (ref. 4),
addressed the potential market for such wastewater treatment systems.
They found that the lack of existing systems and verified design data
was a major obstacle to accomplishment of their study. However, they
concluded the following:

o Under ideal conditions, water hyacinth based systems can be
designed which are highly effective in tertiary treatment of
municipal was tewater.

o Operationally verified design parameters are needed for
hyacinth systems.

257

o For municipal systems designed to meet stringent effluent
standards, hyacinth-based systems offer a possibility for
appreciable cost savings over competitive processes in
construction of completely new facilities.

o The cost advantage will be greater in many types of upgrading
activities.

o Considering only the southern Florida municipal application,
it appears that a reasonable estimate of the savings offered
by hyacinth systems is $165 million over the next 25 years,
with the largest share of this within the next decade.

o Hyacinth treatment systems are in a comparatively early
stage of development. It is quite possible that further
engineering will improve the competitive position of
hyacinth systems.

o Present information on the characteristics of hyacinth
systems is not adequate to bring about implementation on a
significant scale. If, however, the potential advantage
suggested by this analysis can be demonstrated and verified
in actual use, market penetration should be rapid, at least
in southern Florida.

As a result of the Battelle and NASA work, WED Enterprises, a
subsidiary of WALT DISNEY PRODUCTIONS, was sufficiently interested in
the potential for such a system to further investigate its feasibility
by hcsting a meeting of technical experts in July 1976 to review a
plan for a pilot project (ref. 5). The consensus opinion was that the
project had sufficient merit that WED should proceed with a pilot
plant system. This pilot plant, sized for 50,000 GPD, would be the
necessary precursor to the design and economic assessment of a proto-
type I MGD system.

WED acted on this recommendation by forming a team of participants
interested in the further development of this technology and by struc-
turing a program that addresses the complete system; i.e., ultimate
disposal of the hyacinths as well as wastewater treatment. The program
was submitted to EPA for grant funding and was approved August 1,
1978. The original participants included:

o Aquamarine Corporation, the ntins largest producer of
aquatic plant harvesting equipment. They designed and built
the harvesting system for the project.

o Boyle Engineering, a consulting engineering firm that designs
advanced wastewater treatment systems. Headquarterd in
California, the company has branch offices in the Gulf Coast
area, as well as in Florida, the market areas for the hyacinth
system. Boyle in Orlando participated in the preliminary
design phase and produced the final plans and specifications.

258

o Environmental Protection Agency through the Robert S. Kerr
Environmental Research Laboratory in Ada, Oklahoma is
acting as the lead federal organization in this project
and is supervising the spending of grant funds.

o National Aeronautics and Space Administration through the
National Space Technology Laboratories is providing both
expert advice and grant funding for the project.

o Reedy Greek Improvement District is a special legislative
district in Florida which includes all of WALT DISNEY WORLD.
Its legislative charter calls for the district "to promote
and create favorable conditions for the development and
practical application of new and advanced concepts." The
grant request to EPA was made through RCID which provides
budget management and water quality analysis for the project.

o United Gas Pipe Line Company, the major subsidiary of United
Energy Resources, Inc. United is expanding into areas
intended to complement its natural gas transmission business,
particularly the search for alternate sources of supply.
U.G.P.L. has funded extensive research by the Institute of
Gas Technology and has also provided funds for this project.

o Walt Disney Productions through its subsidiaries WED
Enterprises and Reedy Creek Utilities Company developed the
project from conception and is providing program management,
engineering and operations personnel.

Recently additional participants have joined the project:

o University of Arizona's Environmental Research Laboratory
has done considerable research in hyacinth production and
will perform supporting studies for the project in the areas
of growth optimization and nutrient requirements. They are
also involved in the design of a cover over one channel.

o Department of Energy through an interagency agreement with
the EPA will also support the project financially which will
allow for a broadening of the project objectives.

o Gas Research Institute will fund extensive studies in methane
generation with various feedstocks and sewage sludge from
WALT DISNEY WORLD.

Objectives & Schedule

The objectives as stated in the grant proposal were broad but
simple: (1) demonstrate a hyacinth system capable of meeting tertiary
and secondary wastewater treatment standards, (2) demonstrate an energy

259

conservative wastewater treatment system, (3) determine the optimum
system performance characteristics and (4) determine the economics of
a hyacinth based system. None of these objectives have changed but
there has been a shift in emphasis from tertiary to secondary treatment.
A new objective has also been added with the recent addition of DOE
and GRI as participants in the project. It is to experiment with
means of increasing biomass production and converting biomass into
energy.

August 1, 1978 marked the beginning of a four year project. The
final plans and specification were completed by mid November and
construction began February 1, 1979. The end of construction on
May 11, also marked the beginning of operation. Two months were
allowed for seeding and establishing a hyacinth crop. On July 16,
1979 the project started into the Preliminary Operation Phase which
will last three or four months (see figure 1). The objectives of
the Preliminary Operation Phase are to quickly learn if there is an
advantage to operating the system at a low water depth of 15" or a
relatively high depth of 36" and if a rapid harvesting rate of twice
per week is preferred over a slower rate of twice per month.

After the Preliminary Operation Phase two, one year periods, will
follow of relative steady state operation. By the start of the first
winter season a cover will be added over one of the channels. The
influent to the hyacinth ponds shall be primary effluent the first year
and secondary effluent the second. During the steady state periods
the three channels will be used to determine the differences between
covered and uncovered channels and between end and side harvesting.
The optimum water depth and harvesting rate determined during the
Preliminary Operation Phase will be used during the steady state period
and will not be changed unless supporting studies dictate a change.

After two years of steady state operation, the remaining eight to
nine months of the project will be devoted to experimentation with
growth optimization.

Project Components

The project can be broken down into several systems or components:
(1) Production System, (2) Harvesting System, (3) Composting System,
(4) Monitoring Systems and (5) Supporting Studies. Components of the
production system include the three 1/4 acre production channels, the
system piping, utility tie-ins hydraulic control devices, and pumping
stations.

Two submersible pumps, one in the primary clarifier effluent
channel and the other in a filter pump wetwell of the existing RCID
Wastewater Treatment Plant provide the system with primary and/or
secondary effluent. An industrial water supply line has also been
constructed to the project. The three pond influents are metered into
the channels through a flow splitter system. Industrial water and

260.

Figure 1
PRELIMINARY OPERATION PLAN

Channel *Preliminary Steady Steady Other
Operation State State Operation
3-4 Mo. 1st Yr. 2nd Yr. 9 Mo.

1' Depth 2' Depth 2' Depth Possible Operations
2/Week Harvest 1/Week Harvest Control
Primary Effluent Primary Effluent Second. Effluent Series Flow
Parallel Flow Parallel Flow Parallel Flow
No Cover No Cover No cover Maximum Growth
with High
Nutrients and
2 3' Depth 2' Depth 2' Depth Rapid Harvest
2/Week Harvest 1/Week Harvest 1/Week Harvest
Primary Effluent Primary Effluent Second Effluent More Experience
Parallel Flow Parallel Flow Parallel Flow with Harvesting
No Cover No Cover No Cover
Nutrient
Addition
3 3' Depth 2' Depth 2' Depth
2/Month Harvest 1/Week Harvest 1/Week Harvest
Primary Effluent Primary Effluent Second. Effluent
Parallel Flow Parallel Flow Parallel Flow
No Cover Cover Cover

secondary effluent are controlled by turbine meters and control valves.
Control of the primary effluent is by weirs and control valves. The
flow splitter system allows one, two, or three influents in the three
channels. The channels are also interconnected hydraulically to provide
for a variety of experimental modes of operation. (See Figure 2).

The walls of the channels were constructed of reinforced concrete
block on a cast-in-place, reinforced concrete foundation. The channels
(29' x 360') were lined with 20 mil PVC and tacked to the top of the
walls with lumber. PVC booms are tied off to cleats along the top of
the channel walls w~Lth lumber. PVC booms are tied off to cleats along
the top of the channel walls and act as a corral preventing the hyacinths
from packing together at one end of the channel. The water level in the
channels is adjustable by use of effluent weirs. The water depth can be
maintained at 15, 24, or 36 inches. Each of three channels incorporates
the capability to be operated independently and at varied depth if
desired.

The production system is designed hydraulically to handle flows up
to 200,000 gpd but will probably operate at 50,000 gpd. The flow rate
will be set during the fall or spring seasons at the maximum flow rate
which will meet the given effluent standards. The system has been
designed and built to provide the needed flexibility and experimental
control and not as the least expensive way to grow hyacinths.

A cover over one channel will be constructed by December of 1979.
It is currently in the design phase and may include the capacity for
co2 enrichment studies.

There are three pieces of equipment used for harvesting: (1) a
front end loader, (2) a double belt conveyor-chopper and (3) a forage
wagon. All mechanisms in the system are powered by hydraulic motors
connected to the hydraulic pump in the front end loader. The harvesting
system is designed with a capacity of 50 tons per hour, far in excess
of the system requirements.

Harvesting is accomplished by pushing the hyacinths onto the
primary conveyor with a long handled hook. At the end of the primary
conveyor a flail chopper cuts the plants into smaller pieces. The
secondary conveyor loads the chopped plants into the forage wagon which
has a live bed for ease of loading and unloading. With this method a
thick 900 sq. ft. interwoven meat of mature water hyacinths can be
harvested in approximately one hour. Set up and take down time is also
approximately one hour. These times should drop as experience is gained
with the system.

The three channels will be divided in cells 60' long x 29' wide
by floating booms. The harvesting system is completely mobile and can
accomodate harvesting both from the sides and ends of the channels.

262

EFFLUENT EFFLUENT

I _ I
Li

4, 4 I
INFLUENT SERIES (PLUG) FLOW INFLUENT TWO INFLUENTS, PARALLEL FLOW

EFFLUENT EFFLUENT
,~~~~~~~~~~~~~~~
I~~~~~~~~~~~~~~~~~F ]
4 4
I I T � I~~~~- I I

INFLUENT PARALLEL FLOW INFLUENT TWO INFLUENTS
FLOW_____ TWO) INFLUENTS
ONE IN PARALLEL AND ONE IN SERIES

EFFLUENT EFFLUENT

4' I , I

INFLUENT INLUET
INFLUENT ONE IN PARALLEL AND TWO IN SERIES INREE INFLUENTS

Figure 2
SYSTEM MODES

One channel will be covered during the winter and may require end
harvesting only. During the steady state operation, a second uncovered
channel would then be end harvested for comparison with the covered
channel and third channel could be side harvested for comparison with
the second. In all three channels the same harvesting rate, total
hyacinth coverage and individual cell coverage would be maintained.
The floating booms will be used to push the hyacinths in each cell into
a uniform density, thereby allowing measurement of the hyacinth covered
area before and after harvesting. Once a week a 5 square foot area of
plants in each cell would be weighed to get the hyacinth density.

The composting system is a windrow system utilizing a composting
pad and a front end loader. Once the forage wagon is full, it is
moved to the composting pad and unloaded by means of the live bed.
All hyacinth harvested that day are put into a pile. A new pile will
be turned three times during the first week, and once per week for the
remaining five weeks. Temperature and free moisture will be monitored
in the piles for composting control. The desired values are 50-60
percent moisture and 140-150� F. The compost product will be analyzed
quarterly and will be given to the W.D.W. Grounds Maintenance Department
for use on their ornamental tree farm.

The monitoring role can be divided into two functions: (1) baseline
date acquisition and (2) intensive studies. The baseline monitoring
program will provide the long term data on how well the hyacinth system
operates and what can be expected from it, while the intensive studies
will provide the answers to specific questions.

Table 1 is a summary of the baseline monitoring program. The
operators are responsible for recording the daily environmental condi-
tions such as water and air temperature while chemical analysis of the
pond influent and effluent is performed twice per week by the RCID
laboratory. Bi-weekly chemical analysis is considered sufficient in
light of the long hydraulic detention times in the channels (7 to 15
days).

The monitoring system includes equipment, such as four automatic
samplers and an automatic analyser, as well as a record keeping system.
The record keeping system is set up on a daily, weekly, monthly and
quarterly basis depending on the parameter being analysed or recorded.
The daily date summaries kept by the project operator includes flows,
water temperatures, dissovled oxygen concentrations and other environ-
mental information. The weekly data summaries include laboratory
analysis, a summary of the daily records and the composting and har-
vesting data. Similarly the montly records are a summary of the weekly
data summaries.

In order to keep a record of hyacinth production for harvesting
and data analysis purposes it was necessary to devise a method for
determining hyacinth density. The method involves using the floating
booms to get a uniform density and the percentage of water surface
area covered with hyacinths. A five square foot area is segregated

264

I'alJ.e 1
BASELINE MONITORING

MEASUREMENT PERFORMED BY LOCATION FREQUENCY REPORTED

Flow WWTP Operator i&E 3/day i&E, Daily Average

H20 temperature " 1M&E 3/day 1M&E; Daily Average

pH " 1M&E 3/day 1M&E; Daily Average

DO 1M&E 3/day 1M&E; Daily Average

Humidity Pond Vicinity Continuous Low/High; Daily Average

Air temperature " " " " Continuous Low/High; Daily Average

Rainfall " " Continuous Daily

Solar Insolation CEP CEP Continuous Btu/day - m2
pH Lab i&E 2/week

TSS 2" /week

TDS 2" /week

BOD " 2/week

TOD " 2/week

TOC " 2/week

NH3 - N " 2/week

Org - N " " 2/week

Nitrite - N " " 2/week

Nitrate - N " 2/week

ortho - P 2/week

Total P " /week

Total Alkalinity " " 2/week

Total Coliform " 2/week

from the rest of the uniformly bunched hyacinths by using a tool
similar to a cookie cuttler. The segregated hyacinths are then moved
into a basket attached to a hanging scale and are weighed. The weight
divided by 5 square feet gives the density of the hyacinths in that
area and using the densities of the other areas, the weight of the
whole crop can be established.

The major pieces of monitoring equipment are (1) an automatic
analyzer, (2) four refrigerated automatic samplers, (3) moisture and
temperature probes for the composting operation, (4) flow meters and
(5) meteorological instruments.

The RCID laboratory has purchased an automatic sampler in connec-
tion with the project to perform daily water quality analysis and the
intensive studies. This piece of equipment augments a very well
equipped lab which includes an atomic absorption spectrophotometer
and gas chromatograph.

Three composite and one discrete automatic samplers are used at
one influent and three effluent sampling points. The samples are
collected over a 24 hour period but are not proportional to flow. A
flow meter has been purchased which when hooked up to one of the
composite samplers will give a proportional to flow sample.

The monitoring of the composting operation is done with two
pieces of equipment, an insitu moisture meter and a temperature probe.
The control of the operation and the determination of the end of the
composting process will be based on free moisture and temperature.

Flow in and out of the ponds will be recorded from turbine meters
and with rainfall data will be used to determine evapotranspiration
which may be very large in hyacinth systems.

The meteorological instruments include a pyranometer for solar
insolation measurement and an air temperature and humidity meter and
recorder.

The intensive studies will include any monitoring requirements
beyond the baseline monitoring program. Some studies will answer very
specific questions while others provide essential information to the
data base of the project. The intensive studies will include:

(1) Comparison of proportional to flow samples with regular
composite samples.

(2) Determination of day to day variations and hour to hour
variations in effluent BOD, SS, N, P valves.

(3) Determination of BOD, SS, N, P channel profiles.

(4) Performing laboratory water quality analysis quarterly
for metals, pesticides, etc.

266

(5) Performing plant characterization quarterly; relate to
size to plant and location in pond.

(6) Performing compost characterization quarterly.

It may be necessary in the future to incorporate some of the quarterly
analysis into the baseline monitoring program.

The supporting studies are a very important part of the overall
project. The objective of the supporting studies is to provide informa-
tion through laboratory scale research which could influence the
operation of the project. Specific areas of needed research include
growth optimization through micro and/or macronutrient addition, optimum
harvesting schedule, duckweed performance during hyacinth dormant
periods and energy conversion.

The University of Arizona has had for some time an extensive
research program with water hyacinths. They have joined the project as a
participant and will perform many of the supporting studies. Mr. John
Groh of the Environmental Research Laboratory at the University of
Arizona is also involved in the design of the cover.

The energy conversion supporting studies will be performed through
the Gas Research Institute. Anaerobic digestion performed in the lab
of hyacinths, sewage sludge and mixtures of the two will be the subject
of the first studies.

Data Analysis

Water quality analysis was started halfway through the two month
crop establishment period. Secondary effluent was used during this
period because of its high nutrient content and low-potential for causing
anaerobic conditions in the ponds. On May 14, each of the three channels
was seeded with 30 feet of water hyacinth, roughly 10 percent of the
total surface area. In two months the coverage was 100 percent which
gives a doubling time of approximately two weeks. With full coverage,
the pond was meeting the tertiary effluent standard of 5 mg/l BOD,
5 mg/l SS, 3 mg/l T.N., but was not meeting the phosphorus standard
of I mg/l T.P. (see Table 2). However, this data is not sufficient to
make any conclusions about the systems effectiveness in the tertiary
treatment mode.

On July 16, 1979, the pond influent was switched to primary effluent
and the Preliminary Operation Phase was started. The summary of data
collected during the month of August is presented in Table 3. The raw
influent to the Reedy Creek Improvement District (RCID) treatment plant
averaged 200 mg/l SS and 300 mg/l BOD during August. The pond
effluent averaged 22.9 mg/l SS and 27.9 mg/l BOD. Taking into account
a reduced effluent flow rate due to evapotranspiration the combination
of primary clarification and hyacinth treatment does meet the secondary
treatment standard of 90 percent removal of BOD and SS. However, the
data is not sufficient to make any further conclusion at this time due
to the limited time of operation.

267

Table 2

HYACINTH PROJECT DATA SUMMARY

WEEK ENDING 7/15/79

SECONDARY POND
PARAMETER EFFLUENT EFFLUENT

1. FLOW (gpd) 50000

2. pH 6.4 6.4

3. TSS (mg/l) 10.0 2.0

4. BOD (mg/l) 16.0 3.0

5. NH3-N (mg/1) 11.1 0.08

6. ORG.-N (mg/l) 6.87 1.27

7. N03-N (mg/1) 0.20 <0.01

8. TOTAL-N (mg/1) 18.17 1.35

9. ORTHO-P (mg/1) 3.76 2.15

10. TOTAL-P (mg/1) 4.50 2.18

11. H20 TEMP. (�C) 27

12. H20 D.0 (mg/1) 1.6

13. AIR TEMP. (�F) 83

14. HUMIDITY (%) 76

15. INSOLATION (BTU/ft -day) 1170

Summary based on one set of data points.

268

TABLE 3
HYACINTH PROJECT DATA SUMMARY

AUGUST 1979

PRIMARY POND
PARAMETER EFFLUENT EFFLUENT

1. FLOW (gpd) 50000 42000*

2. pH 6.9 6.9

3. TSS (mg/1) 83.2 22.9

4. TDS (mg/l) 285 237

5. BOD (mg/l) 160 27.9

6. NH3 - N (mg/l) 18.38 14.76

7. ORG. - N (mg/l) 9.10 7.18

8. NO3 - N (mg/1) 0.01 0.01

9. TOTAL - N (mg/1) 27.49 21.95

10. ORTHO - P (mg/l) 4.61 4.13

11. TOTAL - P (mg/l) 6.20 4.80

12. ALK. (mg/l) 122 147
8 6
13. TOTAL COLI. (mpn/100ml) 1.05.10 1.43.10

14. H20 TEMP. (�C) 27

15. H20 D.0 (mg/l) 0.6

16. AIR TEMP (�F) 81

17. HUMIDITY (%) 83

18. INSOLATION (BTU/ft -day) 1300

Summary based on 8 sets of data points.
*Flow based on one week's data.

269

The first compost piles were started August B. The data on the
composting operation indicates that water does need to be periodically
added to keep the free moisture content up to 50 percent. No odors
are detectable at the site which also indicates that more water can be
added. The temperature of the piles has not reached the desired level
but it is not clear whether this is due to improper temperature measure-
ment or lack of sufficient free moisture. A new temperature probe is
being acquired for the composting operation.

Data analysis is considered a very important part of the project
and in the future loading rates, detention times, hyacinth growth,
nutrient mass balances, removal rates and removal efficiency will be
calculated as part of the data analysis. The most important factors
are the appropriate removal rates which will be correlated with loading
rates, hyacinth growth and environmental conditions.

SUMMNARY

In general all of the components of the project are operating as
planned but there have been problems. For example, when the ponds were
first seeded the hyacinths were hand picked and placed into the channels.
This was too slow, so a backhoe was used to finish the seeding. This was
a mistake because a great deal of dollarweed and grass was brought in
with the hyacinths. Some of the unwanted species were removed but total
segregation was not possible. The unwanted plant species were harvested
out of the system only after much effort.

The only major concern at this time is whether or not the system
can effectively handle primary effluent. The dissolved oxygen concen-
trations are very low, floating sludge in the open areas has appeared
and there are many fly larvae where the ponds once flourished with
thousands of mosquito fish. Fortunately mosquitoes have not been a
problem so far.

In summary, the hyacinth project at WALT DISNEY WORLD is still in
the process of start up. The scope of the project is quite large and
there are many details to be worked out. The system is unique in its
attempt to provide all the data needed by engineers to design a water
hyacinth wastewater treatment system.

270

REFERENCES

1. B. C. Wolverton, R. C. McDonald, J. Gordon, Water Hyacinths
and Alligator Weeds For Final Filtration of Sewage.
TM-X-72724.

2. B. C. Wolverton, R. C. McDonald, Water Hyacinths For Upgrading
Sewage Lagoons To Meet Advanced Wastewater Treatment Standards:
Part 1. RM-X-72729, October, 1975.

3. B. C. Wolverton, R. C. McDonald, Application of Vascular Aquatic
Plants For Pollution Removal, Energy and Food Production In a
Biological System. TM-X-72726, May, 1975.

4. A. C. Robinson, H. D. Gorman, M. Hillman, W. T. Lawhon, D. L.
Masse and T. A. McClure, An Analysis of The Market Potential
of Water Hyacinth - Based Systems for Municipal Wastewater
Treatment. January 31, 1976.

5. WED Enterprises, EPCOT Technology Meeting - Sewage Filtration
and Energy Production Using Water Hyacinths. July 1, 1976.

271

'UTILIZATION OF WATER HYACINTHS FOR CONTROL OF
NUTRIENTS IN DOMESTIC WASTEWATER -- LAKELANID, FLORIDA

E. Allen Stewart III, P.H ., Dawkins & Associates, Inc.
Environmental Specialist/Engineer Orlando, Florida

The use of water hyacinths (Eichhornia crtassipes) for removal of
nutrients and solids during a demonstration project in Lakeland,
Florida indicates that removals are as a result of more than hyacinth
uptake. Therefore, if design of a hyacinth system is based upon the
uptake and growth kinetics of the plants during cool weather periods,
it appears that an ample safety margin can be maintained. The hyacinth
growth rates were found to be similar to those found in other studies.
A first order design equation based upon the Monod concept using total
nitrogen as the limiting nutrient is presented. Other aspects of the
hyacinth system such as harvesting, crop processing, and -marketing have
been investigated, but are still in need of additional field work before
maximum effectiveness is realized.

INTRODUCTION

Utilizing local funds, the City of Lakeland and Polk County,
Florida have implemented a demonstration project intended to investi-
gate the possibility of utilizing water hyacinths for removal and
recovery of nutrients from secondary effluent prior to discharge into
the nearby Peace River System. This demonstration project presently is
over half completed. It has resulted in the development of a better
understanding of the potential of hyacinths in nutrient removal. It
has also revealed that these systems can be successful only if directed
by an intensive and effective management program designed for efficient
crop handling, selective harvesting, and rapid processing and movement
into the selected market.

SYSTEM DESIGN

While there are presently a few water hyacinth systems in operation
throughout the Southern U.S., there are several factors related to the
Lakeland situation wh*ich make its design considerations somewhat

273

unique. First of all, the nutrient removal requirements are extremely
stringent--1.5 tng/l-TNS and 0.4 ingfl-TP. Secondly, the concept is
being groomed to become part of a regional 201 plan, meaning the size
of the system could be as large as 49,200 cubic meters/day (13 mgd).
This means that unlike smaller systems, there will be a most urgent
need to handle the harvest quickly and efficiently. In essence, the
Lakeland Demonstration Project was intended to investigate the poten-
tial of water hyacinth treatment as a large scale treatment methodology.
The physical design of the demonstration ponds as shown in Figure I
is intended to allow the operator some flexibility in manipulating such
critical parameters as depth, pollutant and hydraulic loading, and
retention time. The three-ponds-in-series concept allows easier
assessment of productivity responses to changes in water quality.
Three harvesting channels intended to accommodate a Hidrostal E5KJL
solids pump or a aqua-guard self-cleaning bar screen were included as
part of the design. Both of these two harvesting possibilities showed
potential for removing large quantities of material at a low energy
and labor input. An efficient harvesting system is one necessary
requirement for a large scale hyacinth system.

PROJECT GOALS

The Lakeland demonstration project, as noted, was intended to
review all aspects of water hyacinth treatment, and to provide some
guidance in developing a design for a large scale system. Basically,
there are three major design questions which must be confronted.
At what rate a-ad by what mechanism~s) do hyacinths remove
nutrients, and what parameters control these rates?
Can the hyacinths be effectively harvested', processed and
dried without over-escalating operating costs?
Are there any marketing potentials for water hyacinths, and
to what degree can the sale counter operating costs?

DESIGN CONSIDERATIONS FOR NUTRIENT REMOVAL

Construction of the three, 0.405 hectare (one-acre) lagoons as
shown in Figure I was sufficiently completed by 12/6/78 to permit
filling. This was done through a 6-inch siphon line from the eastern-
most secondary clarifier at a rate of 0.719 cubic meters/see. (190
gpm). By 12120/78, the ponds were completely'full. At this time about
0.91 metric tons (I ton) of hyacinths were introduced into each pond.
This represented an approximate surface area of 23 square meters/pond
(250 square feet) or a 0.5 percent coverage of the total surface.
Productivity was monitored by setting a 0.093 square meter (I sq.
ft.) chamber within each pond, seeding it with a small plant and
measuring weekly growth changes on a wet weight basis. Later in the
program dry weight density estimates from random samples will be used
to project productivity.
As is shown in Figure 2, there is a good exponential relationship
between change in wet weight and time. Also, there is a notable change
in the rate cf growth between the different ponds. It was also noted

274

' I " GLENDALE STREET

ct LAKELAND

3iCQWASTE TREATMENT
PLANT

~ EXISTING I1
g / SECONDARY
A, l \ (--- "CLARIFIER
0 <. Vi~6 PVC INFLUENT LINE HYACINTH
=~ ' -~'" --'--' -- 0 PONDS
~_. , Z Z Z ,)
Q )) Q< EXI T. z z
X~. %.NCINERATOF ' � �
6" P.V.C.
tJ \ >t t . iEFFLUENT

~~~~~~.275
(}0 EXISTING POLISHING
I/ / / PONDS

Figure 1: Site Plan for Water Hyacinth
Treatment Demonstration
Project-- Lakeland, Florida

275

POND 1

y 14.51 e0,40

rr 0.98
n~

100

TIME~~~~ I 3EK

V ~ ~ ~ ~ ~ ~~~ ~Fgr 2: Grwh ietc qatos o
z ~ ~ ~ ~ ~ ~ ~ ~ ~~~~Lkln 16acint Stud

276 ~ ~ ~ ~ ~ ~ r09

that the chlorophyll content and general health of the plants declined
from Pond 1 to Pond 3. This change was interpreted as a nutrient or
vitamin deficiency. Nitrogen, carbon, and phosphorus levels were
observed to be adequate in all three ponds. Further investigations
showed no changes in potassium or magnesium. Iron, however, was noted
to decline from 0.125 mg/1 to 0.05 mg/1 throughout the system. This
latter concentration is low even for many natural waters in Florida.
Because of this, and because water hyacinths are known to effectively
take up iron, it was decided that iron might be the present limiting
nutrient. To compensate for this deficiency, ferrous sulfate was
added to the ponds at such a rate that the concentration of iron was
maintained near 0.30 mg/I. This replenishment resulted in a general
cessation of this chlorosis.
The equation, as shown in Figure 2, for Pond 1, can be modified
if it is realized that the constant 14.51 represents the initial
standing crop. If this is converted to a variable (Z), this new equa-
tion can be utilized as a design equation for winter conditions as
follows:

y = Ze0.44301x

where y = wet weight produced (metric tons)
x = time in weeks

Based upon the literature it may be legitimately assumed that dry weight
is 0.05 y, total P by dry weight is 0.5 percent, and total N by dry
weight is 4.0 percent. Average winter air temperature is 14.40C
(580F) as indicated in Figure 3.
The desired winter standing crop can now be determined by equalibra-
ting with the incoming load of nutrients. For 378.5 cubic
meters/day (100,000 gpd), using 25 mg/1-TN and 6 mg/1-TP, the load is
equal to 9.53 kg/day (21 lbs./day) nitrogen and 2.27 kg/day (5.0 lbs./day)
phosphorus. This is equivalent of 756 kg/day (16,667 lbs./day) of wet
hyacinths or 52,967 kg/week (116,667 lbs./week) of wet hyacinths. This
value can be seen to be equal to Y-Z or A Z. This allows the design
equation to be expressed as follows:

Y - Z = /Z = 443X-Z = 52,967 kg

Setting x as one week, it is found that the desired standing crop
(Z) is 95,027 kg (209,310 pounds wet weight. Using a desired plant
length of 64-76 cm (25-30 inches) and a density of 225 metric tons/ha
(100 tons/acre) (see Figure 4), the indication is that 0.43 ha (1.06
acres) of hyacinths at a wet density of 225 metric tons/ha would handle,
in the winter, 378.5 cubic meters/day (100,000 gpd) of secondary
effluent, using a weekly growth rate coefficient of 0.44301. This
amounts to about 11.8 hectares/million cubic meters daily (11 acres/
mgd). Considering only 75 percent coverage and anticipating a decline
in growth rates in the latter stages, it appears that 21.5 hectares/
million cubic meters daily (20 acres/mgd) would be more realistic.
(This corresponds to a growth rate coefficient of about 0.33).
With this density and acreage the incoming nutrient load would
theoretically be reduced to negligible levels. Unfortunately, the

277

TEMP.oF TEMP. (0C)
90 (32.2)

80IGHS (26.7)

10 I 25.6

50.

40.
DAILY LOWS

30.

~~~~~~~~~~~~~~~~~~~~~20..~~~~~~~ ~~~~~(-6.7)

10. (-12.2)

JANUARY 1979 FEBRUARY 1979 MARCH, 1979

1 ib 1 1 '5 2' 25 3'01 1'0 5 2'0 25 I 1'0 1'5 2b 25

Figure 3: Temperature Profiles at Lakeland
WWTP During Phase 1 of the
Hyacinth Demonstration Project

. 200
(448)

150
(336)

z -

- I-_ 100
> o (224)

_ 50 /
(112)
, I

O 15 30 45
(38.1) (76.2) (114.3)
TOTAL LENGTH IN INCHES
(CM)

Figure 4: Estimated Hyacinth Density
Based Upon Plant Length
[Wolverton, 1977]

279

nitrogen to phosphorus ratio of the plant material is lower in the
wastewater than in the plant material. This means that at some point
nitrogen may become a limiting factor and productivity will decline
much in the way when iron was noted to be deficient in Pond 3. The
question is, at which concentrations will this occur?
Musil and Breen (1977), two South African researchers, evaluated
the growth kinetics of water hyacinths through the Monod limiting
nutrient enzyme equation --

u=U (S )
K +S

where U = specific growth rate
U = maximum specific growth rate
S = limiting nutrient concentration
Ks = half saturation constant; i.e. when U = 0.5U.

This equation is similar to that used in determining bacterial
growth kinetics in activated sludge. In their investigations, Musil
and Breen (1977) determined that nitrate (NO3) was the limiting growth
factor. In fact, they implied that other nitrogen forms are not
utilized by the hyacinths.
"NH4-N. supplied in culture, however, had no effect on growth. This
is in agreement with Sculthorpe (1967) who suggested that the NH+4 ion
does not act as a nitrogen source for hyacinth plants."
Unfortunately, the concept of nitrate as being the most important,
and perhaps the only nitrogen source for hyacinths, does not agree with
data collected so far in the Lakeland study. For example, Musil and
Breen (1977) projected that Ks for NO- is 21.74 mg/l as NO- or 4.91
mg/l NO- as N. The concentration in Pond 1 during this period of
testing3averaged 0.25 mg/l NO as N, while in Pond 3 it averaged 4.0
mg/l NO-_N. Applying this information to the Monod equation, the
projected growth rates would be 0.06 U for Pond 1 and 0.48 U for
Pond 3. Obviously such a difference did not occur. They further
determined that the maximum growth rate (U) for hyacinths is 0.1145
g-wet weight/g-day. This implies that in Pond 1 the growth should be
0.00687/day and Pond 3 should be 0.05496/day. In reality, using the
best fit equations for Pond 1 and Pond 3, it can be determined that the
growth rates averaged 0.065/day for Pond 1 and 0.043/day for Pond 3.
If total nitrogen, instead of just nitrate (NO3) is used with the
Musil and Breen (1977) findings, then with Pond 1, at an average TN
concentration of 19.8 mg/1-TN and with Pond 3 at an average concentra-
tion of 10.5 mg/1-TN, the projected growth rates are 0.091/day for Pond
1 and 0.081/day for Pond 3 at 250C. Using the Van'tHoff rate for
adjustment to temperature, it is projected that at 150C (590F) the
maximum growth rate would be 0.057/day and the subsequent rates in
each pond would be 0.046/day for Pond 1 and 0.041/day for Pond 3. This
is a fairly close projection for Pond 3 but somewhat low for Pond 1.
The projected trend, however, is comparable to actual field data.
The work of Misil and Breen (1977) is most helpful in developing
and understanding the growth kinetics of hyacinths in the Lakeland

280

situation. Some caution must be taken, however, when trying to express
growth rate kinetics in terms of one nutrient.
There was noticeable change in water quality as the percent in
hyacinth coverage changed as is shown in Table 1, and Figures 5 and 6.
The most relevant observations were as follows:
Oxygen levels were maintained at adequate levels, even below
the hyacinth mats. In Pond 1, where the lowest levels would be
expected, the DO rarely fell below 2.0 mg/l anywhere in the system.
Oxygen levels were often above saturation in Pond 3 because of the
dominance of phytoplankton.
Changes in pH were from neutral or near neutral to slightly
alkaline. Again, this was due to algae production in Pond 3.
BOD and SS were reduced somewhat, particularly later in the
program. Cgnstant algae blooms in Pond 3, however, keep these levels
higher than what will be expected when coverage is complete.
Nitrogen and phosphorus uptake exceeded that expected for the
measured crop density of 99 metric tons/ha (44 wet tons/acre) as is
shown in Figures 5 and 6. This additional uptake apparently is
related to uptake within other compartments of the ecosystem.
Water color and turbidity were reduced noticeably throughout
the system except during extremely active algae blooms.
Dissolved solids were noted to decrease somewhat despite the
high evapotranspiration. This is probably due to selective uptake
of certain ions such as ferrous ion, calcium, and chlorides.
Coliform reduction was quite dramatic. This correlates well
with the literature.
Nitrogen transormation appeared at first to be towards
nitrification. As coverage increased, however, nitrate was noted to
decrease throughout the system. The exact nature of nitrogen trans-
formation throughout the ponds is undoubtedly quite complex. The
fact is, however, that whether the hyacinths are directly using organic
and ammonia nitrogen, or whether they are using only nitrate which is
being supplied by nitrifying bacteria, a limiting growth factor related
to the nitrogen species present is not demonstrated by thi~s study. If
hyacinths are in fact dependent upon nitrate, as suggested by Musil
and Breen (1977), then they are quite effective in supporting an active
nitrifying population within their root systems.
Perhaps the most dramatic change noted throughout the system was
the change in biological composition and diversity. Pond I was
characterized by large hyacinths with a root to total plant length
ratio of about 1:3 to 1:4. The roots often supported an extensively
developed bacterial slime. In areas exposed to light, epiphytic
algae was also noted. Macroinvertebrates were restricted to chironomid
larvae, larvae of the mosquito Culex quincifaciatus and a small unidenti-
fied snail. Populations of two fish species, Gambusia affinis and
Poecilia latipinna were noted to be surviving quite well. At one point
the fish population appeared to approach about 11 fish per square meter.
Young fish were noted in late February, indicating successful breeding.
Mosquito larvae population at its peak approached about 2.6 million/
cubic meters or an estimated 2642 grams wet or 264 grams dry weight per
cubic meter. Assuming that these larvae are about 1.5 percent phos-
phorus on a dry weight basis, it can be estimated that about 15 kg (33
pounds) of phosphorus are tied up in their biomass. If 5 percent hatch

281

TABLE 1

BIWEEKLY WATER QUALITY DATA SHEET (COMPOSITE SAMPLES)
WATER HYACINTH DEMONSTRATION PROJECT

y Air Fecal*
T Air ~~~~~~~~~~~~~~~~~Coliforms
Flow Water T DO' NO-3-N TKN TN Ortho P TP BOD5> SS TS No./100 Remarks and
Date cfs mgd T AVG pH* mg/l mg/I mg/l mg/I mg/I mg/I mg/l mg/I mg/I ml Observations
Influent 0.190 66 2.9 0.56 19.06 19.62 6.94 - % coverage - 0%
12/15 Effluent - - 6.7 0.30 21.6 21.90 7.39
Influent 0.190 - 67 3.2 0.37 19.20 19.57 4.72 6.67 - % coverage - 1%
12/29 Effluent - - 8.0 0.41 14.30 14.71 4.99 5.61
Influent 0.190 - 52 4.0 0.34 20.14 20.48 - 6.59 %coverage -3%
1/22. Effluent - - 7.5 1.70 12.24 13.94 - 6.14
Influent 0.190 - 65 4.5 0.24 23.20 23.44 6.93 - - % coverage - 4%
1/25 Effluent - 8.5 1.52 12.80 14.32 - 6.93
Influent 0.085 61 55 7.23 2.2 0.1 20.7 20.8 6.1 7.7 24 12 411 TNTC % coverage - 12%
2/12 Effluent 60 - 7.67 8.2 6.0 7.4 13.4 5.3 6.5 15 7 403 840
Influent 0.084 60 57 7.38 3.4 0.3 22.1 12.4 6.0 6.9 13 5 409 TNTC % coverage - 12%
2/14. Effluent 0.065 68 8.67 15.0 5.0 7.1 12.1 5.0 4.9 10 2 395 870
Influent 0.086 66 57 7.40 5.8 0.4 24.0 24.4 5.5 12.5 50 17 411 TNTC %coverage- 16%
2/19. Effluent 0.049 68 9.10 11.0 3.6 6.8 10.4 2.5 9.0 36 30 376 500
Influent 0.084 72 66 7.22 3.9 0.45 19.5 20.0 4.8 6.0 18 39 423 TNTC % coverage - 16%
2/21. Effluent 70 - 9.42 14.8 2.9 5.5 8.4 2.0 2.6 11 39 423 130
Influent 0.086 62 53 7.40 4.4 0.06 21.4 21.46 5.5 5.5 20 5 394 TNTC % coverage 23%
2/26. Effluent 58 8.95 9.6 2.5 5.5 8.0 2.0 2.5 18 28 386 780
Influent - - - - 8.0 0.2 20.3 20.5 5.5 8.0 24 14 - % coverage - 23%
2/28. Effluent - - 18.6 2.0 5.8 7.8 0.5 18 28
Influent 0.072 68 70 7.15 2.9 0.36 16.5 16.9 4.5 12 10 379 TNTC % coverage - 32%
3/5 Effluent 66 9.0 6.7 0.2 4.5 4.7 1.8 2.2 7 20 374 700

* Grab samples instead of composite at influent and effluent stations.

TABLE 1
(Continued)
BIWEEKLY WATER QUALITY DATA SHEET (COMPOSITE SAMPLES)
WATER HYACINTH DEMONSTRATION PROJECT

Fecal*
Water Coliforms
Date Flow T Air DO* NO-3-N TKN TN Ortho P TP BOD * SS TS No./100 Remarks and
cfs mgd AVG T ph* mg/I mg/I mg/I mg/I mg/I mg/I mg/ mg/I mg/I ml Observations

Influent 0.071 68 58 7.12 3.5 0.36 17.3 17.7 4.5 4.5 18 22 380 TNTC % coveraae - 38%
3/7 Effluent 67 9.13 1.2 0.42 4.2 4.6 2.0 2.7 14 20 342 680
Influent 0.065 68 68 7.0 3.6 0.71 12.9 13.6 2.5 15 1 5 326 TNTC % coverage - 42%
3/14 Effluent 72 7.95 5.4 0.01 4.3 4.3 0.7 17 16 321 650
Influent 0.064 75 68 7.05 6.2 0.54 15.1 15.6 4.0 5.0 24 45 420 % coverage - 45%
3/21 Effluent 73 8.80 4.2 0.20 5.7 5.9 0.8 1.2 21 18 376
Influent 70 59 6.85 3.2 0.64 18.6 19.2 4.25 5.0 92 447 Spraying for
3/27 Effluent 67 7.53 4.1 0.006 3.7 3.7 5.5 7.0 8 378 Mosquito Larvae
Influent 0.258 84 83 7.10 4.2 0.2 11.8 12.0 4.3 19 13 366
6/20 Effluent 82 83 6.80 1.6 0.1 2.0 2.1 5.6 10 1 339
Influent 0.240 82 79 7.10 4.2 0.3 8.5 8.8 4.8 8 4 345
6/27 Effluent 81 79 6.65 1.6 0.0 1.6 1.6 3.5 4 0 321
Influent 0.154 84 83 7.09 2.2 0.13 6.6 6.7 3.3 20 8 294
7/12. Effluent 83 83 6.54 1.0 0.06 0.9 1.0 0.6 3 1 323
Influent 0.120 85 85 7.10 6.4 0.20 13.4 13.6 3.0 24 13 355
7/19 Effluent 83 85 6.80 3.2 0.012 1.1 1.1 1.8 1 10 294
Influent 0.177 87 87 7.00 3.4 0.17 13.7 13.9 3.8 28 23 357
7/26 Effluent 87 87 6.90 5.1 0 0.8 0.8 2.3 1 0 263
Influent 0.225 85 83 6.76 1.6 0 13.4 13.4 5.0 32 36 377
8/9 Effluent 84 83 6.62 2.6 0 1.4 1.4 3.1 3 7 258
Influent 0.235 84 83 6.63 0.70 0.0 27.2 27.3 5.0 24 14 328
8/23 Effluent 83 83 6.90 4.8 0 4.2 4.2 3.8 7 12 231

'Grab samples instead of composite at influent and effluent stations.

100-

90-

80-- DESIRED
REMOVAL LEVEL (92%)

70- PROJECTED REMOVALS AT
PRESENT DENSITY OF 99 METRIC /
TONS/ha (44 TONS/ACRE)

60-

PERCENT
pCOVERAGE 50-/ / OVSERVED REMOVALS
COVERAGE 50- y= o.699x-17.11
r = 0.87
n� 12
40- /

30-

PROJECTED
20- REMOVALSAT
DENSITY OF
224 METRIC TONS/ha
10-0 T/ /S/ACRE) Figure 5: Observed and Projected Trends
/ / |10-~~~~~~~~~ on Nitrogen Removal Within the
Lakeland Hyacinth System

1' 2'0 3'0 4' 50 6 7'0 80 90 Ibo

PERCENT REMOVAL (NITROGEN)

100-
DESIRED REMOVAL
LEVEL (92%)

90- I

80- I
PROJECTED
REMOVALS OF
E EXISTING
70- DENSITY OF
99 METRIC TONS/ha
(44 TONS/ACRE)

60- I
PERCENT
COVERAGE
50-COVERAGE OBSERVED REMOVAL
5�-, \"y = 0.425 X + 13
r=0.83
n=12

40-

PROJECTED REMOVALS
30- / AT DENSITY OF
224 METRIC TONS/ha
(100 TONS/ACRE)

20-

10- IFigure 6: Observed and Projected Trends
in Phosphorus Removal Within the
Lakeland Hyacinth System

10 0io d 4'0 5'0 6'0 7 80o 9'0 10
PERCENT REMOVAL (PHOSPHORUS)

each day, it can be determined that about .75 kg (1.65 pounds) of
phosphorus is removed daily by mosquitoes alone. This accounts for a
33 percent removal of the daily load. Looking at Figure 6 it now
becomes evident why the observed nutrient removals can be greater than
the projected removal from productivity alone. Unfortunately, mosquito
larvae are not a desirable larval form. Other insects, however, might
well provide some assistance in nutrient control within the ponds.
The impact of the food web upon nutrient removal, particularly
phosphorus, was demonstrated following an intensive spraying of diesel
fuel for mosquito control. Upon dying, the larvae apparently released
their phosphorus into the pond systems, causing the effluent concentra-
tion to increase from 0.7 mg/l to over 6.0 mg/l. It is important then
to adopt a mosquito control program that does minimal harm to other
invertebrates and plants and assures that a large mosquito larvae
population does not develop.
In Pond 2 the ecosystem appeared to be much more diverse. The fish
population grew extremely fast, as the fish appeared to favor this
particular lagoon. The invertebrate population consisted of a dragonfly
larvae, amphipods, damselfly larvae, various water beetles and their
larvae, several types of freshwater mollusks, cray fish, snapping
shrimp, and oligochaete and annelid worms. In addition to Gambusia and
Poecilia populations, several Fundulus species (topwater minnows) were
noted as well as a killifish species. Tadpole populations were also
noted to be developing. Tadpoles, which are a vertebrate larval form,
may also serve in nutrient control, much in the same manner as mosquito
larvae.
The hyacinths in Pond 2 suffered slightly from chlorosis (a noted
iron deficiency). The root to total plant length was about 1:2 to
1:3. The roots were clean as compared to Pond 1, and often supported
many invertebrate species. The larvae of the Culux mosquito were
noticeably scarce, often showing population of less than 270 per square
meter.
Pond 3 showed an even greater diversity of invertebrate and fish
life. Mosquito larvae were virtually absent except in small isolated
areas. The hyacinths were very chiorotic prior to iron treatment, with
a root total plant ratio of 1:1.5 to 1:2.
A detailed population and species diversity study was not made
during this first phase of the project. Once a stable ecosystem has
been established, however, an attempt will be made to identify the
more critical species involved in the nutrient dynamics.
Based upon the water quality and flow data and the productivity
rates, a nutrient and water budget for the ponds was projected. This
information is graphically illustrated in Figures 7 and S. Shown in
Figure 7 is a projection of the fate of nutrients and water during the
104 days of Phase 1. Presented in Figure 8 is a projection of nutrient
flows for a stable system based upon the data collected during Phase 1.
Figure B is based upon weekly harvesting with an average growth rate
coefficient of 0.33 and the assumption that at 1.5 mg/l total nitrogen,
the growth rate will have decreased by 75 percent. The interesting
point here is that nitrogen may have to be added to the system, perhaps
as much as is contributed initially by the wastewater. This may
accommodate complete phosphorus control. The need and cost for this
"Tfertilizer" nitrogen will be determined during Phase 2.

286

H20 (3.5 MG) 13,248 CUBIC METERS
LARVAL RELEASE
EVAPOTRANSPIRATION P - (104 LB.) 47 Kg.
N - (520 LB.) 236 Kg.

DENITRIFICATION (63 LB.) -N 29 Kg- N

HYACI NTHS
INPUT / = (360 LB.) 164 K
P = (54 LB.) 25 Kg.
OUTPUT

NITROGEN (2330L.B.) 1059 Kg.-

PHOSPHORUS (753 LB.) 342 Kg. I H20 = (11.1 MG) 42,014 CUBIC METERS

WATER N = (1,187 LB.) 539 Kg.
EFFLUENT =(13.4 MG).50,719 CUBIC METERS
INVERTEBRATES ' SEDIMENTS
N P =(485 LB.) 220 Kg.
RAIN = (1.2 MG) 4600 CUBIC METERS
RAIN N (1.2 MG) 4600 CUBIC METERS \ N = (200 LB.) 91 Kg. P = (70 LB.) 32 Kg.
TOTAL =(14.6 MG) 55,319CUBICMETERS P= (40 LB.) 18 Kg.

POND SYSTEM

Figure 7: Nutrient and Water Budget
Projected During 104 Days of
Phase I of the Hyacinth
Demonstration Project

H20 = (4.2 MG) 15,897 CUBIC METERS
DENITRIFICATION (63 LB.) - N 29 Kg. -N

INPUTS _ / HARVEST NITROGEN = (4647 LB.) 2108 Kg.
PHOSPHORUS = (697 LB.) 316 Kg.
NITROGEN (2330 LB.) 1059 Kg. / WATER = (0.26 MG) 984 CUBIC METERS
PHOSPHORUS (753 LB.) 342 Kg. LARVAL
-"'WATER /RELEASE NITROGEN = (250 LB.) 113 Kg.
WATER
EFFLUENT = (13.4 MG) 50,719 CUBIC METERS PHOSPHORUS = (34 LB.) 15 Kg.
RAIN = (1.2MG) 4600 CUBIC METERS STANDING
CROP OUTPUTS
TOTAL = (14.6MG) 55,319 CUBIC METERS 200 TONS
NITROGEN= (127 LB.) 58 Kg

wco \ PHOSPHORUS = (34 LB.) 15 Kg
CO
WATER = (10.14 MG) 38,380 CUBIC METERS

SEDIMENTS
IN EQUILIBRIUM
FERTILIZER
NITROGEN (2,920 LB.) 1325 Kg. ESTABLISHED
ANIMAL
POPULATION
(ASSUMPTION THAT HARVESTING IS DONE WEEKLY)

POND SYSTEM

Figure 8: Projected Nutrient and Water
Budget During Typical 104 Days
During Stabilized Conditions
of Hyacinth Treatment System

HARVESTING, PROCESSING AND DRYING

Most of the work dealing with harvesting, processing and drying was
modeled after the work by Bagnall (1976). Using a 30.4 cm (12-inch)
screw press designed by Dr. Bagnall, it was found that from 1.8-3.6
metric tons (2-4 tons) of wet hyacinths could be processed per hour.
The press was driven by a 50 HP tractor with power take-off. If a
properly designed feed system were used, it would be quite possible for
the press to require only one operator. Estimated energy consumption
for pressing whole hyacinths is approximately 6.2 kwh/ton or a cost
of approximately 28�/metric ton (25C/ton). The press results in
a reduction of moisture content from 95 percent to approximately 85
percent. The resultant water loss is about 666 kg/metric ton (1,330
lbs./ton) or a volume loss of 666 liters/ton (160 gallons/ton). The
juice is extremely high in solids -- over 2 percent -- and in
nutrients. It is estimated that about 47,850 liter/day (10,000
gallons/day) of this juice will be produced for each 3.785 cubic meters/
day (one million gallons/day) of plant capacity. Handling of this
material represents an additional design problem. Its similarity to
sewage sludge makes it somewhat compatible with several existing
technologies. Bagnall (1979) presently is investigating the use of
this material for methane production. Other possibilities are to
settle and recover the suspended solids and incorporate these with the
remaining pressed harvest. The supernatent could be returned to the
influent side of the treatment facility.
If the hyacinths are chopped prior to pressing, it is possible to
increase the rate of pressing to about 6.4-9.0 metric tons/hour (7-10
tons/hour). It was found that by placing a cutting element on the
Hidrostal pump used for harvesting that the plants could be effectively
chopped during the harvesting phase. Early tests on a 5"-5 HP/1150
RPM pump reveal a potential harvest rate of about 1.8 metric tons/hour
(2 tons/hour). Considerable difficulty, however, was encountered with
intake blockage. This made the pumping operation inefficient and labor
intensive. It is felt that with a larger intake and higher drive unit
(17 HP) that the pump could be successfully modified to harvest about
20 tons/hour. The energy consumption for the pump in this case would
amount to about 0.64 kwh/ton or 2.8�/metric ton (2.5�/ton). Labor
costs, considering one operator at $10/hour, amount to 55C/metric ton
(50�/ton). Compared to the conventional approach of using a dragline
which harvests at about the same rate the total cost of 57.8C/metric
ton (53C/ton) is quite inexpensive. The dragline operating cost is
approximately $1.87/metric ton ($1.70/ton).
The other harvesting consideration is to use a conveyor type
system such as a self-cleaning bar screen. Bagnall (1979) has designed
a harvester with a 1/2-1 HP drive unit that can remove up to 18 metric
tons/hour (20 tons/hour). Again, considering a one man operation, it
appears that this method of harvesting may cost only slightly more than
55C/metric ton (50�/ton), with the energy demand about 0.004 kwh/metric
ton (0.04 kwh/ton). However, with the conveyor, a separate chopping
system will be required.
Once pressed the hyacinths are dried upon a direct insolation solar
dryer. At a loading rate of about 12.2 kg/square meter (2.5 lbs./sq.
ft.) these dryers, when protected from the rain, have shown the

289

capability to consistently reduce the moisture content to about 20
percent in five days. The present dryers cost approximately $10.78/
sq. meter ($1/sq. ft.). If they were to be built in such a way that
they were logistically efficient and physically strong enough to last
at least five years, however, it is estimated that the cost would be
about $32.28/sq. meter ($3/sq. ft.). This would elevate the capital
cost estimate for drying to about $66,050/million liters-day ($250,000/
mgd), not including land purchase. Properly designed, however, the
solar dryer system will have virtually no energy demand, and labor
costs should be no more than two persons per 4,650 sq. meters (50,000
square feet) of dryer. This amounts to approximately 93�/wet metric
ton (85�/wet ton) of harvested hyacinths for drying. It is felt
that certain design features could be added to the dryers to decrease
the drying time, and subsequently reduce the overall labor costs. The
most notable of these improvements would be to make it possible to
easily turn and spread the material on the dryer on a daily basis.
Another idea is to augment the drying process with a continuous,
heated air type dryer. This would relieve the demands upon the direct
insolation dryers from 15-20 percent to 40-55 percent moisture. The
continuous flow dryer would be an integral part of a feed pelletizing
system.

MARKETING POTENTIAL

While there may be several marketing pathways for water hyacinths,
the Lakeland study has placed more emphasis on their feed potential.
It is felt that a feed produced from water hyacinth~ ,fiber concen-
trate, and taste and vitamin additives will make up the major portion
of a complete dairy or beef feed rationing. Working with a local feed
producer, hyacinths at 20 percent moisture have already successfully
been included as a pelletized feed on a small scale. These hyacinths,
which contain around 20 percent crude protein on a dry weight basis ,
theoretically represent an inexpensive X high quality source of
digestible nutrients and minerals when fed at about 20 percent of the
total ration. Their estimated value, at 20 percent moisture is about
$22-$33/metric ton ($20-$30/ton). This amounts to an estimated cost
recovery of about $30,383/million liters-day ($115,000/mgd).
As of yet, this feed has not been fed to actual test animals. More
detailed work will be needed to check levels of toxic materials which
may interfere with the concept's viability. Preliminary laboratory
tests, however, indicate that the material is suitable. Presently, the
City of Lakeland is awaiting reply on a request for EPA funding to
further investigate this feed option.
The market potential in Florida alone for dairy cattle is about
4,085 metric tons/day (4,500 tons/day) of feed. The hyacinth demand
would be twenty percent of this, or 817 metric tons/day (900 tons/day)
(at 20 percent moisture). This correlates to what would be produced
daily by about 0.22 million cubic meters/day (58 mgd) of domestic
wastewater. There is evidence, therefore, that water hyacinth treat-
ment would have to be utilized by approximately 20 percent of all
wastewater systems within Florida before the State's dairy market
would become saturated. Considering the possibility of an expanded

290

national and international market, and the possibility of use with
other livestock, it can be deduced that there is a rather expansive
potential market.

PROBLEM AREAS

Frost

During the winter months the temperature fell below freezing twice.
During the most intensive exposure, temperatures were at -30C (270F)
for three hours. This resulted in some damage to the outer leaves,
but did not destroy the plants, nor did it noticeably retard their
productivity. According to Penfound and Earle (1948), the hyacinth
will not be injured to a point where recovery will not occur until the
temperatures fall below -50C (230F for 12 continuous hours, or below
-3oC (270F) for 48 continuous hours. Such occurrences are extremely
rare in Florida. To counter the impacts of such rare instances, a
spray system could be utilized to protect 30 percent of the crop.
The remaining 70 percent could be harvested. Replacement of this
standing crop would occur in approximately 15 days, during which time
the nutrient allocation may be exceeded. This, however, would be a
brief violation,, which would not result in an actual violation based
upon annual or monthly allowances. The assessment at this point is
that the winters in Lakeland will pose no major threat to the
systems viability, nor will any measures taken to prevent frost
damage be cost prohibitive. The actual projected costs for frost
prevention will be presented in the final project evaluation.

Mosquitoes

The major problem encountered during the early phase of the project
was the development of huge populations of the mosquito Culex
quincifaciatus. Once a large fish population was established, however,
and the system stabilized, the mosquito population virtually was
eliminated. As of yet, they 'have not reappeared. Control measures
considered along with fish populations are parasitic nematodes
(Peterson; 1975) and monomolecular alcohols (Levy; 1979). From review
of other hyacinth projects, it appears that biological control is
adequate for elimination of significant mosquito populations.

Phosphorus Removal

During the summer months, once the ponds filled with hyacinths, it
was found that an effluent could be consistently produced at concentra-
tion of 2.0 mg/1-TN, 4 mg/1-BOD, and 4 mg/1-SS. Phosphorus levels,
however, have fluctuated between 0.2 mg/l and 4 mg/I. As noted, the
nutrient ratios in the wastewater are not conducive to phosphorus
removal. Furthermore, it is felt that sloughing of tissue from older
plants may be contributing to this problem. Regardless, it appears
that additional management practices or perhaps additional treatment
regimes may be required to control phosphorus. One concept is to
apread the recovered effluent on a rapid infiltration system prior to

291

final disposal. 1Kore consistent and selective harvesting, more inten-
sive ecological management, and increased detention times may also be
utilized for enhancement of phosphorus removal capabilities. Consider-
able work is needed in evaluating the phosphorus removal mechanisms
within these hyacinth systems.

Politics and Funding

Since its first consideration as a feasible treatment method to be
included in 201 planning in Lakeland, the use of water hyacin ths have
met almost constant opposition from state and federal environmental
agencies. The basic reasoning has been that it was not a proven
technology. The fact is that almost all advanced waste treatment
methods are not really proven technologies. This has been the major
force which instigated the innovative and alternative technology
support written into PL95-217. Fortunately, water hyacinths are now
included as an innovative land application method, although the quoted
nutrient removal reliabilities may be somewhat conservative. No
201 in the country at this time, however, is receiving Federal dollars
for design and construction of a water hyacinth system.
As noted, this demonstration project was totally funded by local
dollars -- despite a formal request to EPA for $80,000 R&D funds. The
rejection of these funds came shortly after a nearby private group
received almost ten times that amount to construct and implement a
hyacinth project. This gesture was understandably interpreted as an
inequity. As might be expected, it encouraged a feeling of distrust
towards the Federal government. This continual refusal of participa-
tion by EPA has created a generally cautious attitude in some of the
local officials. Dealing with some of these political problems, which,
in all truthfulness, have been largely created by EPA's reluctance to
properly interpret and implement the directives of PL95-217, will
undoubtedly be the major obstacle confronting completion of this
project and the Lakeland 201.

292

REFERENCES

1. Bagnall, L. O. (1976). Intermediate-Technology Screw Presses for
Dewatering Aquatic Plants, Institute of Food and Agricultural
Sciences. University of Florida, Gainesville.

2. Bagnall, L. O. (1979). Associate Professor Agricultural Engineer-
ing, University of Florida, Gainesville, Personal Communications.

3. Levy, R. (1979). Research Entomologist. Lee County Mosquito
Control District, Fort Myers, Florida, Personal Communication.

4. Musil, C. F. and C. M. Breen (1977). The Application of Growth
Kinetics to the Control of Eichhornia Crassipes (Mort) Solms.
through nutrient removal by mechanical harvesting. Hydrobiologia
53,2/165-171.

5. Penfound, W. T. and I. T. Earle (1948). The Biology of the Water
Hyacinth. Ecol. Mono 18:447-478.

6. Peterson, J. J. (1975). Penetration and Development of the
Mermithid Nematode Reesimetis Nielseni in Eighteen Species of
Mosquitos. Journal of Nematology 7:3;297-210.

7. Sculthrope, C. 0. (1967). The Biology of Aquatic Vascular Plants.
London: Arnold.

8. Wolverton, B. C. and P. C. McDonald (1978). Upgrading Facultative
Waste Stabilization Ponds with Bascular Aquatic Plants. NASA NSTL
Station, Mississippi. ERL Report 172.

293

Other Aquatic Processes
Session

Photo of the recently completed Solar AquaCell system built
at Hercules, California. Comminuted wastewater passes through
the two stage anaerobic AquaCells on the right side of the
picture, designed to provide 12-20 days detention. The waste
water then passes through an aerated facultative AquaCell to
maximize oxygen transfer and additional AquaCells covered
with water hyacinths and duckweeds. The insert depicts plastic
BIOWEB structures that provide increased surface area for
microbial growth in the anaerobic and aerated AquaCell units.

OTHER AQUATIC PROCESSES: SESSION SUMMARY

The session on "Other Aquatic Systems for Wastewater Treatment," as the
title implies, included diverse papers. It is revealing to consider the reasons
for the many different approaches to wastewater treatment that have been repre-
sented at this seminar. If there is one thing common to all of these practices,
it is that each has a unique set of man-made and natural ecological constraints.

Among the man-made constraints are: (1) the volume and make-up of the waste
to be treated,, characteristics of which vary from community to community,
seasonally and diurnally, and with the degree of pretreatment provided; (2) the
standards for wastewater effluent discharge that must be met by the treatment
system; and, (3) the economic basis and the resources available for the project.

Ecological laws, of course, form the basis for our efforts to utilize
natural aquatic processes to treat and recycle waste, and lead to much of the
diversity seen in aquaculture treatment systems. Although many aquatic plants
are cosmopolitan, some will perform better than others under particular climatic
conditions. Similarly, the choice of organisms for use in wastewater treatment
will vary with the type of waste to be treated; an organism's tolerances of the
chemical and physical extremes of the wastewater environment will in part deter-
mine its suitability for use in a given aquaculture treatment system. Finally,
impounded wastewater forms no less complex an ecosystem than natural surface
waters. Many of the same natural processes that produce fluctuations in dissolved
oxygen and carbon dioxide content, light intensity, reproduction rates, and
a host of other chemical, physical and biological parameters in natural waters,
also operate in wastewater treatment projects involving aquaculture systems.

The possible combinations of these man-made and natural variables alone
guarantee that a wide range of conditions will occur in aquaculture treatment
systems. To this point, the speaker's responses have been almost as varied and
can be best summarized by the following quote from the speaker Darrell L. King:

"A great variety of biological, chemical, and physical factors interact and
feedback to set limits on the ability of natural ecosystems to process
wastewater. An understanding of these ecological limits allows better
design of alternative wastewater management systems which can be tailored
to fit local environmental and wastewater conditions relative to local
wastewater effluent standards."

Session Moderators:

A. W. Knight, Professor
Department of Land, Air and Water Resources
University of California
Davis, California 95616

Frank T. Carlson
Office of Water Research and Technology
Department of the Interior
Washington, DC 20240

297

SOME ECOLOGICAL LIMITS TO THE USE OF
ALTERNATIVE SYSTEMS FOR WASTEWATER
MANAGEMENT

Darrell L. King, Institute of Water Research, Michigan State
University, East Lansing, Michigan 48824

A great variety of biological, chemical, and physical factors
interact and feedback to set limits on the ability of natural ecosystems
to process wastewater. An understanding of these ecological limits
allows better design of alternative wastewater management systems which
can be tailored to fit local environmental and wastewater conditions
relative to local wastewater effluent standards. Ecological interac-
tions responsible for oxygen supply for BOD satisfaction, plant pro-
duction, and nutrient removal and recycle by alternative wastewater
systems are considered for aquatic ecosystems and combinations of
aquatic and terrestrial ecosystems.

INTRODUCTION

When considering the use of natural ecosystems as means of waste-
water treatment, it is tempting to picture a series of ponds, perhaps
coupled with a terrestrial irrigation system, which will satisfy many
different desires. Often such conjecture includes a natural solar
powered wastewater recycling system which produces large amounts of food
stocks, serves as a recreational site; produces minimal sludge and
recharges groundwater or surface water with water from which all nitro-
gen, phosphorus, deleterious organics, metals, bacteria, and viruses
have been removed. Zero surface discharge and optimal fish cultures are
other attributes often desired from such systems. But, accumulating
information from various operating aquatic, terrestrial, and combination
aquatic-terrestrial wastewater recycle systems casts serious doubt on
the ability to meet these various goals with any one system with current
management practices.
This suggests certain limits to the use of such systems, but it
does not indicate that these natural systems have no place in waste-
water treatment. The standard of comparison should not be whether or
not these natural systems meet all of these utopian goals, but rather
how they compare with modern mechanical systems in meeting wastewater
standards. In the long term, the most meaningful comparison may well be
that of wastewater treatment efficiency per fossil fuel energy input.

299

But, to trtly judge their effectiveness, such alternative systems must
be designed and operated to take full advantage of the various natural
processes within the constraints imposed by the complex physical, chemi-
cal, and biological interactions which characterize, control, and limit
natural ecosystem function. Without careful attention to such ecologi-
cal limits, these alternative wastewater management systems may fail to
yield desired results in any of several different areas.
The purpose of this paper is to consider some of the ecological
limits to various suggested uses of alternative wastewater management
systems which rely on natural ecological processes.

THE AQUATIC ECOSYSTEM

The usual comparison between conventional mechanical wastewater
treatment systems and those which use natural ecological processes
stress the differences and minimize the similarities. And yet, even the
modern activated sludge process relies on biological concentration of
organics by a portion of the aquatic ecosystem supported by mechanical
intervention. Oxygen required for bacterial respiration is supplied by
mechanical means and excess respiratory biomass is mechanically removed
as sludge; but, even in this ecologically simple, largely controlled
system, shifts in species of biota at times cause an undesirable change
in performance.
Ponds of some sort are an integral feature of most alternative
wastewater treatment systems where their use may range from BOD reduc-
tion to storage of wastewater prior to application to some type of
terrestrial system. Regardless of the use of the pond, impoundment of
wastewater markedly increases the complexity of the aquatic system used
as a wastewater treatment process. The decreased reliance on energy
demanding mechanical processes is accompanied by a loss of control of
the system. The efficiency of wastewater renovation is then dependent
upon the limits imposed by the natural pond ecosystem.
The first use of the pond ecosystem for wastewater treatment in
this country was the sewage lagoon. Initiated in Texas and North Dakota
the use of lagoons expanded greatly after the study at Fayette, Missouri,
(1) indicated their significant removal of BOD5 and coliform bacteria.
The most widely used lagoon is the faculative lagoon usually
operated from three to six feet deep with an anaerobic bottom covered by
an aerobic surface layer maintained by planktonic algae. The aquatic
process responsible for wastewater renovation in lagoons is often viewed
(2) (3) as a symbiotic arrangement in which bacterial release of
nutrients from waste organics supports algal photosynthesis which in
turn supplies oxygen to the bacteria. The aquatic ecosystem of the
lagoon is far more complex than this and relies heavily on the alka-
linity system for the carbon dioxide required for algal photosynthesis
(4). in fact, the carbonate-~bicarbonate alkalinity system serves as a
bank from which carbon dioxide can be withdrawn during the daylight
hours for sufficient photosynthetic oxygen production to meet the night
respiratory demands. Night respiratory release of carbon dioxide
recharges the alkalinity system prior to the next sunrise if the lagoon
is in some degree of balance, This process which allows capture of
respiratory carbon dioxide and allows diurnal variation of dissolved

300

oxygen from near I mg 02/29 to levels in excess of 30 mg 02/k and diurnal
pH variation of up to 3 pH units is depicted in equations 1, 2, and 3 as
the sum of the first and second dissociations of carbonic acid.

HC0+ H+ co + HOH (1)
3 2

HCO3~ co3 + H~(2)

2 HCO3 co 2+co3�+H+ (3)

The significantly greater departure of the dissolved oxygen concen-
tration of the lagoon from atmospheric saturation during daylight super-
saturation than during the undersaturation of the night yields a -net
loss of photosynthetic oxygen to the air when light intensity and tem-
perature allow active algal photosynthesis. This leads to a net extrac-
tion of carbon dioxide from the alkalinity, an increase in pH, and a
decrease in the free carbon dioxide concentration of the water as a
function of increased time of detention of the wastewater within the
lagoon (5). The resulting decreased carbon dioxide level causes changes
in algal species culminating in dominance by the blue-green algae (4).
The probability of establishment of blue-green algal dominance thus
increases as a function of increased detention time of the wastewater
within the lagoon. The blue-green algae, buoyed up by their gas
vacuoles, do not readily sink in the lagoon and thus increase the algal
content of the effluent from the pond, thereby yielding elevated ef flu-
ent suspended solids concentrations.
Regardless of the algal type, production of oxygen by the lagoon
algae is accompanied by the production of considerable organic matter
in the form of algal protoplasm. Use of photosynthetic oxygen to meet
the oxygen demand imposed by bacterial respiration of waste organics
leaves an oxygen demand in the water in the form of algal protoplasm
which must be satisfied at a future time. Exportation of algal laden
lagoon effluent to receiving streams places the burden of meeting oxygen
demand imposed by the lagoon algae on the stream ecosystem (6)(7).
The expansion of the use of lagoons was based largely on the
results of studies which showed lagoons to yield excellent removals of
both coliform bacteria and BOD5. Subsequently, it was shown that for
algal laden lagoon effluents the conventional measurement of BOD5
included only about 20 percent of the ultimate BOD (6)(7) because the
algae do not lyse and release their contents for bacterial attack in
the five day incubation period within the BOD bottle. However, as long
as the standard applied was B0D5, lagoons generally met standards.
Addition of a suspended solids standard forced consideration of the
algae in the effluent, not adequately measured by BOD5, and most lagoons
no longer met standards. This called for an energy dependent mechanical
intervention for removal of algae and some of the apparent advantage of
the lagoon was lost.

NUTRIENT REMOVAL BY PONDS

Continued upgrading of wastewater standards has in many areas

301,

included imposition of nutrient limits on wastewater effluents, with the
nutrients most commonly considered for elimination being phosphorus and
nitrogen. Harvest of aquatic vegetation and animal products, sorption
on the pond bottom and chemical precipitation under the high pH condi-
tions generated in such ponds are all viewed as good methods of nutrient
removal within wastewater ponds.
The potential for natural aquatic systems to remove nutrients is
under study at the Water Quality Management Facility (WQMF) at Michigan
State University. This facility, charged with 0.5 MGD of good quality
secondary effluent, allows evaluation of the potential of both aquatic
and terrestrial systems for the management of nutrient rich wastewater
(8). Within the WQMF, the wastewater flows by gravity through a series
of four ponds to a pumphouse from which it is applied as spray irriga-
tion to a 130 ha site containing oldfields, forest, and crop land. The
ponds range from 3.23 to 4.98 ha with a total pond surface area of 16 ha.
Maximum pond depth is 2.4 m at the outlet and mean operating depth is
1.8 m to place the entire pond bottom within the photic zone to encour-
age growth of aquatic macrophytes. The secondary domestic effluent
conveyed to the WQMF contains 16-20 mg N/i and about 5 mg P/i with a
BOD5 usually less than 10 mg/k. The secondary effluent coming into the
pond can be routed directly to the pumphouse or water from any of the
four ponds can be routed to the pumphouse for spray irrigation on the
terrestrial site.
In response to the nutrient enriched wastewater which enters the
WQMF ponds, aquatic photosynthesis occurs at a rapid rate markedly
accelerating the biogeochemical cycle of carbon, nitrogen, and phospho-
rus. Carbon dioxide uptake from the alkalinity by the algae and
macrophytes within the ponds is accompanied by significant oxygen pro-
duction and pH values often well in excess of 10 during the spring,
summer, and fall months.

PHOSPHORUS REMOVAL

The three mechanisms for phosphorus removal within the pond systems
are sorption on the pond bottom, precipitation as a variety of phos-
phates under high pH, and uptake by plants. Sorption on the bottom
sediments is finite and after slightly over a year of operation, the
phosphorus content in the outlet of the fourth WQMF pond exceeded the
Michigan effluent standard of 1 mg P/i. Phosphorus is precipitated
during periods of high pH, but these precipitates are dissolved during
low pH characteristic of respiratory periods. Macrophyte harvest, even
if 100 percent efficient, would allow only about 10 percent removal of
annual phosphorus load (9). In effect, then, there is no natural
mechanism at work in pond ecosystems which will allow sufficient phos-
phorus removal in ponds to meet the Michigan phosphorus discharge
standard at any reasonable loading rate. For a short period immediately
after construction, ponds may show excellent phosphorus removal. But,
this will cease once the pond bottom becomes saturated with phosphorus
at equilibrium with the wastewater phosphorus concentration. Thus, it
appears that pond systems will remove phosphorus just long enough for
the designer and contractor to collect their fee and leave town.

302

NITROGEN REMOVAL

Incoming nitrate nitrogen is rapidly taken up by both the algae and
macrophytes, but particularly by the algae in the WQMF. The resulting
plant mass is in turn rapidly cycled through the remainder of the aqua-
tic community, particularly the bacteria, with the nitrogen being
released as the ammonium ion. Under the high pH maintained within the
pond by continued photosynthetic extraction of carbon dioxide from the
alkalinity, the ammonium ion is rapidly dissociated to free ammonia gas
according to equation 4 for which the pK is about 9.3 at summer tempera-
tures.

The free ammonia thus generated is rapidly lost to the air. During
occasional periods of respiration following collapse of an algal bloom,
the lowered pH and decreased oxygen concentration may allow some deni-
trification with the consequent release of nitrogen gas. However, the
generally very low nitrate concentrations, high pH, and high oxygen
concentrations suggest that the overwhelming bulk of the nitrogen loss
from the WQMF occurs as direct ammonia loss to the atmosphere. Harvest
of macrophytes yields some nitrogen removal but even with near maximal
harvest only 9 percent of the observed nitrogen loss was accounted for
in plants harvested from the WQMF ponds (9).
The extreme dynamic nature of the ponds and the associated loss of
nitrogen to the atmosphere as ammonia yields an efficient means of
removing nitrogen from wastewater. During 1976, when 0.5 MOD of secon-
dary effluent was passed through the four pond system, total nitrogen
concentration decreased as function of detention time as shown in
equation 5.

N ~~-. 03t
N =N 0e (5)

Where: Nt = total nitrogen concentration mg N/Z at time t
N0= initial total nitrogen concentration in mg N/t
t =time in days

Fifteen to twenty mg/i total nitrogen entering the WQMF ponds was
reduced to about 0.5 mg total nitrogen/liter with a detention time of
120 days, while inorganic nitrogen concentration was at times as low as
0.05 mg N/t in the fourth pond after about a 120 day detention period.

MEETING EFFLUENT STANDARDS

The rapid cycling of nitrogen to ammonia and the elevated pH, both
maintained in wastewater ponds by the abundance of phosphorus available
to support aquatic photosynthesis, yields an extremely efficient system
for the removal of nitrogen from wastewater. However, phosphorus
removal by the pond ecosystem is not sufficient to allow effluent from
the ponds to meet the effluent phosphorus standards currently in force

303

in the state of Michigan. To meet this effluent phosphorus standard,
the WQMF pond effluent is spray irrigated on an adjacent terrestrial
system. This integral step required for phosphorus removal allows some
recycle of nutrients to terrestrial biomass. To gain such recycle, the
WQMF must be operated as a combination aquatic and terrestrial system.
In Michigan, during the period from April to October, the active
growth of terrestrial vegetation incorporates nutrients from the waste-
water applied to the land. To allow nitrogen addition to the la-ad to
meet plant needs during this period, it is necessary to minimize deten-
tion time in the ponds where nitrogen in the wastewater is rapidly lost
to the air. This is accomplished on the WQMF by irrigating a mixture
of secondary effluent and water from the first pond during the spring
and summer months. With the absence of terrestrial vegetative growth
during the remainder of the year, nitrogen in the wastewater applied to
the land is not removed and infiltrates to the groundwater. Water
irrigated on the land during the winter infiltrates well (10). But, to
protect the groundwater from nitrate nitrogen, the wastewater applied to
the land during the winter must have an extremely low nitrogen content.
Nitrogen is efficiently removed from the wastewater impounded in the
ponds during the spring and summer months. By October the ponds are
full of was tewater with a sufficiently low nitrogen content to allow
was tewater irrigation during the fall and winter months without eleva-
tion of groundwater nitrogen levels.
The ability of terrestrial vegetation to remove nitrogen from
wastewater during the spring and summer is dependent on the type of
terrestrial vegetation. Oldfield grasses are quite efficient, agricul-
tural crops show variable efficiency, depending on the crop type, and
forests are not efficient at removing nitrogen before it infiltrates to
the groundwater (11). Overall, the combination of ponds and land which
comprise the WQMF can be operated in a fashion which meets the stringent
effluent water standards of Michigan. Nitrogen is lost to the air as
ammonia and nitrogen gas and phosphorus is either sorbed on the terres-
trial soils or harvested as terrestrial biomass. Operated in this
manner, the WQMF approaches zero wastewater discharge.

AQUACULTURE IN WASTEWATER PONDS

The long history of pond culture of a variety of fish in the Orient
in ponds charged with was tewater suggests an intriguing potential for
converting water-borne wastes to foodstocks within the United States.
However, it should be recognized that the wastewater aquacultural
successes of the Orient are allowed because they do not have to meet
either the environmental standards on the effluent from their ponds or
the public health standards on the product, both of which must be met
within the United States. Our wastewater effluent standards include BOD
and suspended solids removal and in some locations nutrient limitations
as well. Before aquacultural products from such systems can be marketed
as foodstocks in this country, they must be shown to be free from patho-
genic bacteria and viruses as well as having an extremely low burden of
the great variety of toxic and carcinogenic materials characteristic of
wastewater from a highly technical society.
Even if such public health considerations can be overcome, there is
great difficulty in operating a pond system to meet modern effluent

304

standards while simultaneously maximizing aquacultural yield. It is
obvious that any attempt at aquaculture in wastewater ponds must not
impair the ability of the pond ecosystem to renovate wastewater.
The nutrient content of wastewater is not in balance with the needs
of pond biota. Phosphorus availability far exceeds nitrogen availability
which in turn far exceeds carbon availability relative to plant needs.
Carbon dioxide can be gained from the air while nitrogen is lost as
ammonia or nitrogen gas to the air. Phosphorus is removed only by plant
uptake or by some portion of the phosphorus sedimentary cycle.
When wastewater is impounded, photosynthesis by phytoplankton algae,
attached periphytic algae, and submerged macrophytes extracts carbon
dioxide from the alkalinity system at a rate greater than it can be
resupplied from respiration and from the air, thereby raising the pH of
the water. The amount of pH elevation is directly related to the deten-
tion time in that the longer the water is held the greater is the carbon
extraction from the alkalinity. A continually lowered carbon dioxide
content associated with continued detention yields a change in algal
species culminating in the buoyant blue-green algae (12).
Such rapid photosynthesis supplies the energy necessary for rapid
cycling of the various nitrogen forms to ammonia, which, at the existing
high pH, is lost to the atmosphere as a gas. Thus, with increased deten-
tion time, the ammonia nitrogen concentration will be reduced to the
point where it is no longer toxic to fish. However, at this point the
nitrogen concentration often is no longer sufficient for any algae
except those blue-green algae which can fix atmospheric nitrogen. These
blue-green algae cannot be harvested readily and since they are readily
utilized only by bacteria, they represent an oxygen demand which will be
exerted in the pond. Within the WQMF, bacterial use of such nitrogen
fixing blue-green algae has caused sufficient oxygen depletion to yield
both summer and winter fish kills.
If sufficient zooplankton are present in the pond to control the
mass of green algae and diatoms, the carbon extraction from the alka-
linity may not proceed to the point where blue-green algae dominate.
The addition of zooplanktivorous fish to such systems can reduce the
zooplankton control of the algae to the point where sufficient algal
mass accumulates to force a carbon dioxide level low enough for blue-
green algal dominance (13). Phytoplanktivorous fish, such as some of
the oriental carp, would be able to maintain a green algal dominance if
the fish stocking rate was matched with the wastewater detention time
and the algal growth rate in such a manner that the algal content of the
effluent did not exceed effluent suspended solids standards. This is an
extremely difficult balance to maintain and it is illegal to import such
fish into most states.
Attempts to raise and harvest submerged macrophytes can be thwarted
by adding fish which crop the zooplankton, thereby allowing rapid expan-
sion of algal populations to the point where they limit the light avail-
able to the macrophytes. In this instance, macrophytes are replaced by
phytoplankton, often blue-green algae.
Cage culture of fish in wastewater ponds is limited by the char-
acteristic high pH of the ponds. The waste products of the fish in the
cage represent a point source of ammonia which, at the high pH, rapidly
dissociates to ammonia gas which is toxic to fish. While such ammonia

305

production may not kill the fish, the growth rate of the fish is
retarded (14).
The necessity of balancing this complex set of interacting variables
to produce a product of value without impairing wastewater treatment
efficiency, coupled with the improbability of marketing the product, does
not indicate a great potential for wastewater aquaculture of foodstocks
in the United States at this time.

REFERENCES

1. Neel, J.K., J.H. McDermott, and C.A. Monday, Jr. 1961. Experimental
lagooning of raw sewage at Fayette, Missouri. J. Water Pollut.
Contr. Fed., Vol. 33, pp. 603-641.

2. Cooper, R.C., W.J. Oswald, and J.C. Bronson. 1965. Treatment of
organic industrial wastes by lagooning. Proc. 20th Industrial Waste
Conf., Eng. Ext. Series 118, Purdue Univ., Lafayette, Ind., pp. 351-
364.

3. Rich, L.G. 1963. Unit Processes of Sanitary Engineering. Wiley,
190 p.

4. King, D.L. 1972. Carbon limitation of sewage lagoons. In G.E.
Likens, Ed., Nutrients and Eutrophication, Special Symposium, Am.
Soc. Limnol. and Oceanogr., Vol. 1, pp. 98-110.

5. King, D.L. 1976. Changes in water chemistry induced by algae. In
E.F. Gloyne, J.F. Malina, Jr., and E.M. Davis, Eds., Ponds as a
Wastewater Treatment Alternative, Water Resources Symposium 9, The
Center for Research in Water Resources, Univ. Texas at Austin.

6. Bain, R.C., P.L. McCarty, J.A. Robertson, and W.H. Pierce. 1970.
Effects of an oxidation pond effluent on receiving water in the San
Joaquin river estuary. 2nd International Symposium for Waste Treat-
ment Lagoons, R.E. McKinney, Ed., Lawrence, Kansas, pp. 168-180.

7. King, D.L., A.J. Tolmsoff, and M.J. Atherton. 1970. Effect of
lagoon effluent on a recieving stream. 2nd International Symposium
for Waste Treatment Lagoons, R.E. McKinney, Ed., Lawrence, Kansas,
pp. 159-167.

8. King, D.L. and T.M. Burton. 1979. A combination of aquatic and
terrestrial ecosystems for maximal reuse of domestic wastewater.
Water Reuse Symposium, Water Reuse from Research to Application,
AWWA Research Foundation, Denver, Colorado, Proceedings, Vol. 1,
pp. 714-726.

9. King, D.L. 1978. The role of ponds in land treatment of wastewater.
International Symposium, State of Knowledge in Land Treatment of
Wastewater, U.S. Army Corps of Engineers, Cold Regions Research and
Engineering Laboratory, Hanover, New Hampshire, Vol. 2, pp. 191-198.

306

10. Leland, D.E., D.C. Wiggert, and T.M. Burton. 1979. Winter spray
irrigation of secondary municipal effluent. J. Water Pollut.
Contr. Fed., Vol. 51, pp. 1850-1858.

11. Burton, T.M. 1979. Land application studies on the Water Quality
Management Facility at Michigan State University. 2nd Annual Con-
ference of Applied Research and Practice on Municipal and Industrial
Wastes, Madison, Wisconsin, Sept. 18-21, 1979.

12. King, D.L. 1970. The role of carbon in eutrophication. J. Water
Pollut. Contr. Fed., Vol. 42, pp. 2035-2051.

13. Helfrich, L.A. 1976. Effects of predation by fathead minnows,
Pimphales promelas, on planktonic communities in small eutrophic
ponds. Unpub. Ph.D. Thesis, Michigan State University, 59 p.

14. Duffield, D.J. 1979. Case culture of channel catfish, Ictalurus
punctatus (Rafinesque), in a tertiary wastewater pond and a private
pond in southern Michigan. Unpub. M.S. Thesis, Michigan State
University, 45 p.

307

UTILIZATION OF SILVER AND BIGHEAD CARP
FOR WATER QUALITY IMPROVEMENT

Scott Henderson, Arkansas Game and Fish Commission,
P.O. Box 178, Lonoke, Arkansas 72086

ABSTRACT

Filter feeding fishes, the silver and bighead carp, were
stocked in an existing lagoon treatment system in 1975-76 for
a preliminary evaluation of the effect of the fish on water
quality and the potential of this nutrient source for fish pro-
duction. Positive results have led to an ongoing Environmental
Protection Agency funded study of the efficacy of finfish as a
treatment method in a full scale, six cell (24 acre) treatment
facility at Benton, Arkansas.

Information concerning water quality improvement, fish
production, product utilization and some design considerations
are presented. The promising results, design adaptability,
and pay back possibilities make this an attractive, innovative
alternative.

INTRODUCTION

Fertilization of fish ponds has long been recognized by
the fish culturist as a method of increasing production. The
production of finfishes as a method of reducing fertility is a
relatively new approach that has been stimulated by the in-
creasing need for effective, low cost treatment of wastewater
by small municipalities. The initial emphasis on this and other
"alternative" strategies as opposed to conventional methods was
largely a result of more stringent effluent guidelines and the
high cost of construction and operation of conventional plants.
It seems, however, that the even more recent realization of
the need to conserve energy sources and to recycle what has
previously been discarded as a troublesome waste product has pro-
vided the impetus for exploring new technologies. Also, even
the remote possibility of producing a useful and/or valuable
product from wastewater treatment demands attention.

The Arkansas Game and Fish Commission's interest in this
project evolved from the importation into the state of two
species of Chinese carps by a private fish farmer. The silver
carp, Hypopthalmichthyes molitrix, and bighead carp, Aristichthyes
nobilis, were brought into Arkansas in 1973 with initial interest
resulting from the fact that they were unknown, exotic species
and the possibility of these low trophic level filter feeders
being a beneficial addition to fish production ponds. Conversa-
tions with Dr. S. Y. Lin who did pioneering work with the Chinese

309

carp species in Taiwan and a visit to the Quail Creek Sewage
Treatment Project in Oklahoma during 1973-74 led to the current
interest in wastewater aquaculture.

The fact that many finfish species ranging from the lowly
esteemed common carp, Cyprinis carpio, to the prize sport fish
the muskellunge, Esox masquinongy, have been produced in waste-
water ponds attests to the variety of species amenable to pro-
duction in nutrient rich wastewaters under specific conditions.
The fact that X pounds of fish are produced without supplemental
feeding obviously shows that in one fashion or another, energy
and nutrients are transformed into the very stable form of fish
flesh. This is the reasoning behind one of the basic tenets of
fish culture and management i.e., that within certain limits the
natural productive capacity of a given body of water is increased
by increasing available nutrients. The fish culturist may draw
on a rather large body of available literature resulting from
research and practical experience in determining the proper type
and amounts of fertilizer to add to the culture pond.

If, on the other hand, the objective is to utilize available
nutrients, little is known about the effectiveness of finfish in
general or of any particular species. Common sense dictates
that those fishes that have adapted to feeding at the lower
trophic levels would be most efficient at converting nutrients.
Therefore, those that are able to feed on the primary productiv-
ity, the herbivores, should be considered the most likely can-
didates-for achieving the objective of nutrient utilization. A
group of fishes known as the Chinese carps, in particular the
silver carp, meets this criterion and is the key species in
this study.

Silver and Bighead Carp

The silver and bighead carp are native to the Amur River
basin along the Sino-Soviet border. Stocks of these fish have
been propagated by the Arkansas Game and Fish Commission since
1973 for use in this and other research projects. Both are
filter feeding fishes that feed on free-floating or free-swimming
planktonic organisms throughout their life. These fishes are
capable of reaching a size of 18-23 kg (40-50 lbs.) in four to
five years.

The silver carp exhibits certain characteristics that make
it more desirable for this type of program than native filter
feeding species. The specially adapted gill rakers that have
evolved as the filter for this species are somewhat unique and
are very efficient at filtering extremely small particles from
the water that passes through them. The gill rakers of the
silver carp are similar to a sponge-like plate and are capable
of removing particles as small as four microns in size. The
diet of the silver carp is composed primarily of phytoplankton.

310

The gill rakers of the bighead are filaments that widen at the
distal end and overlap to form a more or less solid filtering
surface. The filter of the bighead is comparable to many native
filter feeders and is not as efficient at removing the smaller
particles as is the silver carp. The majority of the bigheads
diet consists of zooplankton and the larger phytoplankton species.
Both the silver and the bighead are capable of rapid growth, are
not particularly susceptible to common fish diseases, and are
capable of withstanding relatively low dissolved oxygen levels.
For these reasons mentioned above it is believed by the author
that the silver carp should be the central species in a finfish
treatment system. The bighead has certain desirable attributes
but could be replaced by other native fishes.

Description of Project Site

The wastewater treatment plant of the Benton Services Center
was chosen as the site for the study. The primary reasons for
its selection were the multiple ponds available, the capability
of controlling the pattern of flow through the system, and state
ownership which provides greater cooperation and control in
operation of the plant.

The Benton Services Center is under the direction of the
Arkansas Department of Human Services. The center provides both
mental and alcohol rehabilitation programs, a nursing home facil-
ity, and serves as a work release center for the Arkansas Depart-
ment of Corrections. While numbers vary, there are approximately
1,000 persons residing at the center full time. Other than day-
time and around-the-clock patient care personnel, the center
maintains its own water treatment plant, fire station, laundry,
food services department and a rather large maintenance and
grounds staff. There are also several residences for staff
members located on the grounds. There are in all, approximately
1,000 full time employees at the center with some contributing
to the wastewater load during working hours six days per week
and others around-the-clock.

Other than the collective individual needs, the biggest
contributors of wastewater to the system are the laundry and
food services. The laundry is in operation six days per week
supplying the needs of the entire Benton facility and food ser-
vices prepares three meals per day for all residents and at
least one for every employee. The character of the raw waste-
water is fairly typical of that produced by small municipalities
with no major industrial users.

The physical facilities of the wastewater treatment plant
include (1) a bar screen and grinder for reducing the size of
larger debris entering the system, (2) a clarifier, (3) an
aerobic digester (this is a converted anaerobic system providing

311

mechanical aeration to the solids from the clarifier, majority
of the water enters the lagoons from the clarifier), and six
oxidation ponds with a total surface area of 10.2 ha (24 acresk.
The average daily flow of wastewater into the system is 1,711m*/
day (0.45MGD), the average organic load is 444 kg (977 lbs.) of
BOD5 per day, and 208.6 kg (459 lbs.) of suspended solids per day.

Preliminary Study (1975-76)

Methods

In 1975, a preliminary study using only the silver and big-
head carp was begun at the Benton site. At the outset of the
study, the flow pattern through the ponds was arranged so there
would be two completely independent three pond series. The total
influent load was passed through a division weir with one-half of
the total volume going into the initial pond in each of the series.
The ponds in each series were numbered in the order the water
passed through them i.e., Ponds 1A and lB received the sewage
influent and the water was discharged from 3A and 3B. The ponds
designated the "A" series were stocked with fish and the "B"
series received no fish and was used as the control. (See
Appendix IA)

The "A" ponds were stocked with fish as follows:

Pond IA (1.76 ha) - 450 grass carp (5-7 cm each)
1,275 silver carp (10-13 cm each)
280 bighead carp (10-13 cm each)
Pond 2A (1.55 ha) - 400 grass carp (5-7 cm each)
5,250 silver carp (5-7 cm each)
380 bighead carp (10-13 cm each)
Pond 3A (1.56 ha) -20,000 silver carp (5-7 cm each)
400 bighead carp (10-13 cm each)

Water samples were taken twice weekly from each of the six ponds.
One sample was taken at sunrise and the other at midday. One
liter grab samples were taken at the effluent from each pond.
Water quality characteristics measured for each sample were:

Dissolved Oxygen Carbon Dioxide Suspended Solids
Air/Water temperature Color Phosphate, Total
Turbidity Fecal Coliform NH3 - N
Conductivity Plankton Count N02 - N
pH BOD5 N03 - N

HACH pre-measured reagents and spectrophotometric methods were
used in making most determinations. Many testing procedures did
not comply with accepted Standard Methods.

Results

There being no other apparent differences in the two sets
of ponds, it is assumed that any differences in effluent quality
can be attributed to the presence of the fish.

312

The most notable differences in effluent quality were found
to be in BOD5 and the types of phytoplankton organisms present.
Both are felt to be interrelated. For the annual average, the
BOD5 of the effluent from the ponds without fish was 37.6% higher
than the series containing the fish. The phytoplankton popula-
tion in Pond 3A (fish present) was never dominated by blue-green
species and no plankton die-offs were observed or recorded. In
Pond 3B (no fish present), dense blue-green blooms, floating mats,
periodic die-offs and associated odors were frequent occurrences
throughout the warmer months. The continued healthy green
phytoplankton population with continuous 02 production in Pond
3A with no die-offs causing additional oxygen demands is attri-
buted to the constant "grazing" of the fish which resulted in
decreased BOD5 levels. For the most part, the remaining param-
eters measured were lower for the ponds containing the fish as
compared to those without. With the exception of an overall
reduction of NH3-N of 27% in the fish ponds, the differences were
small. While the accuracy of the methods used are questionable,
it is believed that they lend themselves to direct comparison.
Graphic representation of parameters measured during this
preliminary study are presented in Appendix IB.

Fish Production:

Based on preliminary water quality data, it was considered
very doubtful that fish could tolerate the low DO levels in Pond
IA and none survived longer than the fourth week after introduc-
tion. DO levels in Pond 2A appeared marginal for the support
of fish life, however, it seemed the feeding activity of the
fishes themselves provided a stabilizing influence on the usually
wide diurnal fluctuations of oxygen concentration. Oxygen re-
lated fish kills occurred in winter and early spring in this
pond as a result of abrupt seasonal changes as is typical of
fertile surface waters. In both cases, fish were restocked re-
placing those lost. No problems occurred throughout the year
in Pond 3A as oxygen levels remained well within limits necessary
for propagation of these fish.

The fish were harvested at the end of this study and weighed
for total production figures. A total of 6,546 kg/ha (6,003.8 lbs.
per acre) were produced during the period from August, 1975 to
December, 1976. This encompassed one full growing season in
Arkansas. Total weight gain can be attributed to utilization of
natural food produced within the ponds as no supplemental feeds
were added to the ponds at any time.

Present Investigations (1977-1980)

The promising results of the preliminary study described
above have led to continuing efforts at further evaluating this
method of wastewater treatment. A research grant from EPA pro-
vided funds for minor site alterations and upgrading water quality

313

monitoring techniques to acceptable Standard Methods for waste-
water. An additional federal grant from the National Marine
Fisheries Service is supporting further investigations in the
possibility of fish production and product utilization.

Site Alterations and Present Pond Operation

The Benton Services Center treatment plant is again being
used. Minor alterations in the existing facility were made
prior to stocking the fish and instituting routine water quality
monitoring. The existing six ponds were dewatered, sludge build-
up was removed and the ponds regraded to their original contour
with some minor changes to facilitate the harvest of the fish.
All ponds average 1.2-1.3 m in depth with the bottoms being
graded to the deepest point of approximately 2 m. The flow
pattern was arranged so the wastewater flows through each of the
six ponds in series with the ponds numbered one-six in the order
they receive the wastewater. All wastewater entering the plant
is lifted by pumping into Pond 1 where it travels by gravity
flow - drop in elevation of approximately 0.76 m (2.5 ft.) - to
the surface discharge from Pond 6.

By utilizing the existing piping system, the water flows
into each of the ponds at the midpoint of one levee and out an
adjacent side. To prevent short circuiting and provide maximum
retention time, baffles were constructed diagonally, three-
quartes of the distance across each of the ponds. (See Appendix
IIA) The influent flow rate of 1,711 m3/day (0.45 MGD) allows
for a residence time for the water in the entire six pond system
of 72 days. The individual ponds are approximately equal in
size (range from 1.55-1.8 ha) with a retention time of about 12
days per pond. Four recording flow meters have been installed
across the six ponds. One is placed in a six inch Parshall
Flume measuring influent, two are placed at the outfall of ponds
two and four and the last at the end of the system recording
effluent flow.

All wastewater flows directly into Pond 1 and then serially
through the remaining ponds. Ponds 1 and 2 serve as stabili-
zation and plankton culture ponds and were not stocked with
fish. The remaining four ponds were stocked with fish as follows:

Pond 3 (1.55 ha) - 20,270 silver carp (41 g each)
4,103 bighead carp (32 g each)
Pond 4 (1.8 ha) - 12,198 silver carp (41 g each)
2,052 bighead carp (32 g each)
Pond 5 (1.67 ha) - 12,070 silver carp (41 g each)
2,052 bighead carp (32 g each)
Pond 6 (1.56 ha) - 8,100 silver carp (41 g each)
600 bighead carp (32 g each)
600 channel catfish (300 g each)
100 buffalofish (1.6 kg each)
40 grass carp (0.5 kg each)

314

Water Quality Monitoring

For the present study, one liter grab samples are taken
once weekly (between 7-10 am) from the effluent of each of the
six ponds. All sampling and testing is performed according to
APHA Standard Methods for the Examination of Water and Waste-
water, 14th Edition. Samples are taken and preserved at the
site as prescribed and delivered to the lab facilities of the
Arkansas State Department of Pollution Control and Ecology in
Little Rock, Arkansas where all testing of water quality is
conducted. Water quality parameters measured weekly from each
of the six ponds are:

Air/Water Temperature N03-N
Dissolved Oxygen Conductivity
BOD5 Suspended Solids
Turbidity Total P
NH13-N Fecal Coliform
N02-N Plankton Count & Enumeration

The wastewater entering the plant has an average BOD5 of 260 mg/l
with suspended solids concentration averaging 140 mg/l.

The loading rate for the initial pond is 242.5 kg/ha/day
(244 lbs./acre/day) of BOD5 and 113 kg/ha/day (114.7 lbs./acre/
day) of suspended solids. When this loading rate is applied to
the total available area within all six ponds it amounts to
43.5 kg/ha/day of BOD5 and 20.4 kg/ha/day of suspended solids.

During the first eight months of operation, the system has
reduced BOD5 by 96.4% and suspended solids by 86%.

The present monitoring program has been in effect for nine
months and is scheduled to continue for one full year. Because
of the time factor involved, all water quality data presented
in this report is taken from the first eight months of the study -
December, 1978 through July, 1979.

During this period, the effluent has been within criteria
established for secondary treatment and in many instances
approached levels for advanced secondary treatment. A complete
listing of effluent quality by month is presented in Appendix IIB
and the overall effect on the water quality in each of the ponds
is listed in Appendix IIC.

Fish Production

To monitor the growth rate of the fish within this system,
monthly samples have been taken throughout the growing season
and individual fish weighed, measured, and returned to the pond.
It has been difficult to obtain adequate samples of species
other than the silver and bighead carps due to relatively low

315

stocking densities and the inefficiency of sampling techniques.
Based on sampling information as of August 1 and assuming a
realistic survival rate of 85% of the fish initially stocked,
there is an estimated standing crop of fishes in excess of
22,777 kg (50,000 lbs.) in the four ponds containing fish.
This amounts to a total average production of 3,344 kg/ha
(3,125 lbs./acre) with approximately three months remaining in
Arkansas' growing season.

Product Utilization

Among the many organisms that have been proposed at one
time or another as biological filters for use in wastewater
lagoons, finfish are one of the most easily controlled and
harvested for use utilizing existing state-of-the-art methods.
Present technology exists for processing fisheries products
for an existing market. There is, however, a bureaucratic
"catch 22" preventing any product directly derived from waste-
water being sold for human consumption. While public health
concerns should not be minimized, a low cost source of high
quality protein should not be overlooked with such a flippant
attitude.

Realizing the problems of consumer acceptance and legal
constraints associated with the utilization of fishery products
from wastewater lagoons, a testing program was established at
the beginning of this project. While it is certainly beyond
the scope and budget of this project to consider all possible
contaminants, a private testing lab was contracted to determine
le-els of what was considered to be the most likely pesticides,
heavy metals and pathogenic bacteria present in the system.
Samples -f fish flesh (edible portion) and water from the in-
fluent a - he ponds themselves is being used for the testing.
All proceou. 3s follow accepted standard methods. Quality
control measures practiced by the private lab have been approved
by the Arkansas Department of Pollution Control and Ecology.

Prior to beginning the project, baseline data was estab-
lished by testing influent wastewater and samples of flesh from
hatchery reared fish to be stocked in the lagoons. Subsequent
quarterly sampling has been done on influent wastewater and
both water and fish flesh from two of the four ponds stocked.
The ponds sampled are alternated each quarter. In all sampling,
those contaminants considered were:

Pesticide Scan Metal Scan Path. Bacteria Screen
Aldrin Lead Salmonella/shigella
Dieldrin Copper Staphylococcus
Endrin Cadmium Edwardsiella
Mirex Mercury Clostridium
DDT (and derivitives) Arsenic
Toxaphene
Kepone
PCB

316

With the exception of the metals, copper and mercury, and
staphylococcus bacteria, all samples have shown less than the
standard detection limits or have been negative. In no instance
has any sample been above action guidelines established by FDA
or the Arkansas Department of Health.

Cost Effectiveness

According to EPA report 600/2-76-293 entitled Economic
Assessment of Wastewater Aquaculture Treatment Systems by Upton
Henderson and Frank Wert, 1976, only when finfish aquaculture
was not capable of meeting water quality objectives was it
deemed not to be cost effective when compared to conventional
systems. The report went further to state that aquaculture
wastewater alternatives appear to be economically attractive
regardless of the market for products if water quality goals are
met.

Although there are several possibilities and likely many
useful fishery products yet to be developed, it appears that
the long and the short of the present market lies with the sale
of the product as a food item and by processing it into fish
meal for use as an animal feed supplement. It should be under-
stood that in present day fresh water pond aquaculture the
greatest overhead costs are land, feed, fertilizer and water.
By utilizing this system of wastewater aquaculture, these costs
would be borne by the primary function of water treatment. By
accepting this and other rather basic assumptions within the
framework of present markets, some rather cursory economic pro-
jections can be made.

Silver and bighead carp from the preliminary study were
rendered into fish meal which assayed at a crude protein
content of minimum 55-57%. This is compared to 62% crude
protein for Menhaden meal considered the best product now
available. Oil and fat content were not considered. There
was an estimated 18% return of meal from fresh fish by weight.
Current market prices for pure fish meal, F.O.B. Little Rock,
vary from $4-500 per ton in bulk quantities depending on
season and harvest source. Based on a price of seven-nine cents
per kg (three-four cents per pound) for live fish and an annual
production rate of 6,546 kg/ha as seen in the preliminary study,
a gross return of $430-$575/ha/year ($180-$240/acre/year) could
be realized by processing the fish in this way.

If, on the other hand, the fish were marketed for direct
human consumption at a conservative in the round price of
55-65 cents per kg (25-30 cents/lb.) the gross annual return
would be $3,600-$4,525/ha ($1,500-$1,800/acre). Whatever the
market, any profit realized would certainly be welcomed by
small municipalities to offset treatment costs.

317

APPENDIX IA

Flow pattern anid method of operation of the lagoons
used during the preliminary study, 1975-76.

319

Influent Di v i sion Weir

4- /

POND 1B POND 1A

1.83 ha 1.76 ha

POND 28 POND 2A

1.80 ha 1.55 ha

- I

POND 38 POND 3A

1.56 ha

1.67 ha

L______ J__ __ ___> Effluent
Benton State Hospital Sewage Lagoons. "A" series of ponds stocked
with fish. "B" series of ponds not stocked with fish and used as
control.
321

APPENDIX IB

Comparison of average monthly water quality data of
effluent from the series of ponds with and without fish
during the preliminary study, 1975-76.

323

10~~~~~~~~~~~1 IitI
100 -- I
I'
90-
9o -- I
'9"
10 ~ ~ ~ ~ ~ / $~ 80- / 1

50 tiR i S ~~~~~~~ 0 -" I \
~~~~~~~~~~~10 80-

//~ ~~~~~~~~~~~~60 -

105 -' 0
- .,\5/,,

C., ~ ._ , j-

PER 3IER Pon -Arpeetdb oi ersne ysldln, Pon 3Bb
40-3
3-4

10 I
105

AUG OCT DEC FEB APR JUN AUG AUG OCT DEC FEB APR JUN AUG
SEPT NOV JAN MAR MAY JUL SEPT NOV JAN MAR MAY JULY

TOTAL NUMBER OF PLANKTON ORGANISMS TOTAL SUSPENDED SOLIDS. Pond 3A
PER LITER. Pond 3A 'represented by solid represented by solid line, Pond 3B by
line, Pond 3B by broken line, broken line.

15 --
A
14 --
34-I 70 --
13-- I

12 -- rI l 60 -- 1-/
II--~~~~~ I.

60 --

H 9--
II

p40

H 6-

5-
4--

~1~~~20 -- ,,
I ~~ -

I I I I I I I I I I I I I , I I I I LI .
AUG OCT DEC FEB APR JUN AUG AUG OCT DEC FEB APR JUN AUG
SEPT NOV JAN MAR MAY JUL SEPT NOV JAN MAR MAY JUL

AMMONIA-NITROGEN. Pond 3A repre- TOTALPHOSPHATE. Pond 3A represented
sented by solid line, Pond 3B by broken by solid line, Pond 3B by broken line.
line.,

A ~~~~50-*!
580 -- /1
-I
56o0-- I ~4-
/~~~~
54o0-- / -~
/ ~~~~~~I

~~~~~~~~~~~~~~~~~~~~~~~~/
52 40 -- /
46 ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~ 0--/

~~~~~~~~~~~~~~~~~~~~~~~~~I//j
400~ ~~~~~~~, /
/ N . I /
AUG OCT DE FEB A20--AGAG C E B AR U U
SEP NO\A A U EP O A A A U

460~CNUTIIY --n 'A rersnetyBO'\od3 ereetdb oi
soid ie odJ yboe ie ie od~ yboe ie

10.0 --

10.5 -- \i
tI 'II
I ~~~~~~~~/

.1 ~~~~~~~~/

9.0-

8.5--

,~~~~ ,
oo ~ ~ ~ ~ ~ ~ I I I j I I 5 5

AUG OCT DEC FEB APR JUN AUG
SEPT NOV JAN MAR MAY JUL

pH. Pond 3A represented by solid
line, Pond 3B by broken line.

o 00,000 6

800,000 I20,000
0~ ~ ~~~~~~~~~~~~~~~~~5

700,000 .,.

~~~~~~~~~IFO 400,0 . 000 ~ 2 R

6 00,000 -

200,000 4: 500

100,000 1t~~*.

.4 0 - I-0,

Fecal Coliform. Average number of fecal coliform bacteria found in each
pond during study period,

APPENDIX 11A

Flow pattern and method of operations of the lagoons
used during present investigations.

331

Influent

r I i ~~~~~~~1.76 ha

POND I
1. 83 ha

POND 4
1. 8 h a
I

POND 3
1. 55 ha

I 1 I POND 6
1.56 ha

P~J 1.67 ha II

333

APPENDIX IIB

Average monthly water quality data from samples taken
of final effluent (Pond 6).

335

Pond #6 Pond 1/6
Effluent NH3 (mg/i) Effluent Turbidity (NTU)

* ,-~~~ N) (~~~3 .i~~~ U~~ C' . D 00

4 4~~~~~~~~~~~~~-
01~~~~~~~~~~~~-
VI nli LTI~~~~~~~~~~~~~~~

/ a-H~~~~~~~~~~~~~:

Pond #6 Pond #6
Effluent pH Effluent Total P (mg/i)

0 CD f- C) 00

-'4~~~~~~~~~~~~~~~~~~L

j-71~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~I

CD~~U
b~~~~~~~~~~~~~~~~-

Pond #6 Pond #6
Effluent TSS (mg/1) Effluent BOD (mng/1)

$- $- ~~~N) to I. " I- -
Ln 0 Ln U1 r ) J.- 0' 00 0 N) 4- CN

0 L

L4~~~~~~~~~~~~~~~~~~~~~~~~~~-

L4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.

r%3~~~~~~~~~~~~L

Pond #6 Pond 16
Effluent Conductivity (micromhos/cm) Effluent DO (mg/l)

0 0 0 0 0 .h- OI co 0

~~~~~~~~~~~~~~~~~~~~~co

LI~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~c
tlutlV

b~~~~~~~C
u, 3~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

0 /

7-' U1 U1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~'

N~~~~~~~~~~

C Cf

re J~~~

cl ~~~~~~~~~cA
~~~~~~~� Os~~~~~~~~~~~~~~~~~~~~~0

Pond #6 Pond #6
Effluent - NO3 -N (mg/i) Effluent NO2 - N (mg/i)

o o 0 0 0

~~io pnV1

~~~iO~~~~ 0
ii 3 b~~~~~~
n co~~
0
L: O~~~~~~
U~ n ~

w~~~~~~~~~~~~~~~~'J a) i

:10 9
:'Ji N Q)~~~~~~~~
O~~~~~~~~~~~~~~~~~~~~~~~~0

t j

L~~~O Cc i O~~~~~

APPENDIX IIC

Change in water quality as flow progresses through
each pond in the series. Values listed represent the
average of weekly samples taken during the first eight
months of the study. December, 1978 - July, 1979

343

9.5

9.0

8.5

8.19
8.0 807.92 7.99
7.88

7.5 1 7.49

7.0
Pond #1 Pond #2 Pond #3 Pond #4 Pond #5 Pond #6

7.36
7.06
6.67

6
5.39

4
2.96

2 1.73

Pond #1 Pond #2 Pond #3 Pond #4 Pond #5 Pond #6

345

66.7

28.12

22.18
20 l C o 1 10.89 9.36

Pond #1 Pond #2 Pond #3 Pond #4 Pond #5 Pond #6

100

65.08

=-' 60

40 38.03

29.99

20 18.66 17.05
16.72

Pond #1 Pond #2 Pond #3 Pond #4 Pond #5 Pond #6

346

10.0

8.0

6.42
6.0
5.06 47
rA ~~~~~~~4.78
4Q 4.02
4. o

2.03
2.0 2.0 1.99

Pond #1 Pond d2 Pond #3 Pond #4 Pond #5 Pond #6

0.26
0.25

0.20

r-4

, 0.15

0.11
0.1 0.09

0.05 0,02 0.04

00 F] /
Pond #1 Pond #2 Pond #3 Pond #4 Pond #5 Pond #6

347

0.61
0.6

0,5

,-I
0.4

0.2 0.15
0.04

Pond #1 Pond #2 Pond #3 Pond #4 Pond #5 Pond #6

5.0

4.0
3.61

3.0 3.02
bo 2.87
a,3.3? 2.87 2.68
2.51 2.50

X 2.0

1.0

Pond #1 Pond #2 Pond #3 Pond #4 Pond #5 Pond #6

348

4j
.,4
20
H ~~~~~~~~15.12
12.22

10 8.29 6.19 7.28

Pond #1 Pod) ond #13 Pona ir'- -Ac-d #5 Pond #6

300

250

217.05

185.4 1 72.7

0 150

r-4

H 100 60.7 ~~~~~~~~~~~~59.42

50 ~~~~~~~~~43.16

Pond #1 Pond #2 P on d #3 Pond #4 Pod 5 ond #6

349

500

437.9
4047.-' 3
400
Ii 86.41
'J86.41 370.97 345.25
337.5

300

200
-4i

100

Pond #1 Pond i#2 Pond #3 Pond #4 Pond #5 Pond #6

350

TREATED SEWAGE EFFLUENT AS A NUTRIENT
SOURCE FOR MARINE POLYCULTURE

John H. Ryther, Woods Hole Oceanographic Institution,
Woods Hole, Massachusetts 02543

INTRODUCTION

A biological tertiary sewage treatment-marine aquaculture system
was developed, tested, and evaluated for two years on a "pilot-plant"
scale at the Woods Hole Oceanographic Institution's Environment
Systems Laboratory (ESL - Fig. 1). The effluent from secondary sewage
treatment, mixed with seawater, was used as a source of nutrients to
grow single-celled marine algae (phytoplankton) in mass (35,000 gallon),
continuous flow-through cultures. Harvest from the algal cultures
(experimentally varied from 25% to 75% of the culture volume/day),
diluted with seawater, was fed into 40' x 4' x 5' (deep) cement raceways
containing stacked trays of shellfish. The latter, stocked at densities
ranging from 75,000 to 150,000 animals/raceway (1,500 - 3,000 per tray)
have consisted of different species of oysters and clams, and smaller
numbers of other shellfish.

The phytoplankton removed the nutrients from the sewage effluent,
which varied experimentally from 10 percent to 50 percent in the
effluent-seawater mixture. The shellfish removed the phytoplankton
from the water. Effluent from the shellfish cultures (i.e., the pond
harvest and diluting seawater) prior to its discharge was passed
through a culture of seaweeds, grown in suspended culture in raceways
adjacent to the shellfish cultures, which serve as a final polishing
step, removing nutrients not initially assimilated by the phytoplankton
and those regenerated by excretion of the shellfish and decomposition
of their solid wastes. After initial experimentation with several
seaweed species, research was concentrated on two red algae of potential
commercial value, Gracilaria tikvahiae and Neoagardhiella baileyi (which
contain the polysaccharides, agar and carrageenan respectively).

351

Solid wastes produced by the shellfish and uneaten phytoplankton
supported dense populations of small invertebrates (amphipods,
polychaete worms, etc.). These served as food for secondary commercial
crops of marine animals, the American lobster (Homarus americanus)
and the winter or blackback flounder (Pseudopleuronectes americanus)
which were stocked in respective raceways with the shellfish.

The primary objective of the research was to develop a biological
tertiary sewage treatment process capable of removal of all inorganic
nitrogen from secondary sewage effluent prior to its discharge into
the environment. Earlier studies (1, 2) had established the fact that
nitrogen is the nutrient limiting and controlling algal growth in and
eutrophication of the coastal marine environment. Thus nitrogen
removal may be considered as synonomous with tertiary sewage treatment
of effluents to be discharged to the sea.

The second objective of the process was to develop a marine
aquaculture system consisting of a primary crop of shellfish and
secondary crops of other commercially-valuable marine organisms (sea-
weeds, lobsters, finfish), the value of which would pay for or help
defray the cost of the tertiary sewage treatment process.

Procedures and Results

A. Algae culture and nutrient removal.

Phytoplankton cultures were maintained continuously in five of
the six 35,000 gallon, 2,500 ft2 algae ponds (the sixth pond was held
out of production). The culture ponds, which were approximately
50' x 50' x 3' deep, were constructed from shaped sand and fine
gravel lined with 20 mm black PVC. The exposed edges of the PVC
liners were further covered with a 10 mm PVC "sacrificial" sheet that
could be replaced when and if sun damage occurs. When filled to a
depth of three feet, the pond volume was 35,000 gallons.

The cultures were kept in gentle circulation with two one-third
HP (40 gal/min) cast iron pumps on opposite corners of the ponds.
These recirculated the culture, the return jets entering above the
surface to provide both momentum and aeration. This action was
normally sufficient to keep the algal cells in suspension.

Eight thousand gallons/day of effluent from the Town of Wareham,
Massachusetts, activated sludge secondary sewage treatment plant was
trucked to ESL and discharged into one of three buried 8,000 gallon
fiberglass nutrient storage tanks. From there, the effluent was
pumped to a headbox in the ESL mechanical room and then distributed
by gravity to the ponds.

352

Two to four of the pond cultures were grown on various mixtures
of sewage effluent and seawater and the remainder on an inorganic
nutrient medium which was adjusted to the nitrogen and phosphorus
levels of sewage effluent (typically 20-25 mg/l N and 10-15 mg/i P).
The number of ponds operated on sewage effluent depended upon the
sewage concentration and flow rate (percent pond exchange/day) employed.
For example, at 50 percent pond turnover with 25 percent sewage effluent
and 75 percent seawater, over 4,000 gallons/day of effluent is required
for each pond, over half the daily supply. Since it was desired to
obtain maximum performance data of the algal cultures without any
chance of their being nutrient limited, the usual procedure was to
operate only two ponds with sewage effluent, at concentrations and
turnover rates comparable to the above example, particularly during
the high productivity period in summer, even although all nutrients
were not removed.

Three times a week (14, W, F) the inorganic -nitrogen and phos-
phorus input (sewage and seawater) and discharge (pond harvest) and
the particulate (i.e., algal) carbon and nitrogen in the discharge
were monitored. From these data, daily nutrient uptake and algal
production could be calculated and expressed on a per volume and per
area basis. This information is summarized in Table I on a seasonal
basis,, extrapolated to show areal requirements in acres per MGD of
effluent (10,000 capita) for complete tertiary treatment (nitrogen
removal). This ranged from 26 acres in summer to 77 acres in winter,
with 19 acres for the best short-term performance in midsummer.

In contrast to earlier experience with effluent from other
treatment plants, in which the nitrogen is predominantly in the form
of ammonia, the Wareham effluent is highly oxidized with 0 - 30 percent
ammonia (depending upon time of year, performance of the plant, and
perhaps other factors), the remaining nitrogen fraction being nitrate.
This apparently does not affect algal production, though there is
evidence that the ammonia is preferentially used first by the plants
if a mixture of the two forms is present. To more nearly simulate
sewage effluent in the cultures that were fed inorganic chamical
nutrient medium, the ammonium chloride was replaced by an equivalent
amount of sodium nitrate. However, the latter proved unsuccessful,
possibly due to toxic contaminants in the industrial-grade chemicals
used, so practice reverted to the use of ammonium chloride. Generally
speaking, the performance of the cultures with respect to algal growth
and nutrient removal were the same whether sewage effluent or the
chemical nutrient medium, adjusted to the same nitrogen concentration,
were used.

During a period of approximately two months, due to malfunction
or poor operation of the treatment plant, the effluent was of poor
quality, containing large quantities of undigested suspended solids.
The resulting turbidity inhibited algal production and the dissolved
and particulate organic matter made monitoring of nutrient utilization
and algal production impossible during that period. That experience
points out the necessity for high quality, completely oxidized, and
clear secondary effluent for the successful operation and monitoring
of the algal growth system.

353

Table 1. Mean phytoplankton production and nitrogen removal in effluent-enriched

cultures, on a seasonal basis. (Figures rounded)

Winter Spring-Fall Summer Maximum

Mean algal production

g dry weight/m2/day (ash-free) 3 6 9 12

Nitrogen removal

g/m 3/day 0.3 0.6 0.9 1.2

lbs/acre/day (cultures 1 m deep) 2.7 5.4 7.1 10.8

Equivalent volume effluent treated1

MGD/acre .013 .026 .039 .052

Area requirement

acres/MGD effluent treated 77 37 26 19

Assuming 24 mg N/1 effluent or 200 lbs N/million gallons effluent.

254

Despite considerable effort and experimentation, including filling
the algae ponds with lI-filtered seawater and inoculation with large
(several hundred liter) cultures of several different species of uni-
cellular algae, no success was obtained in controlling the species of
algae that developed and persisted in the ponds. Cultures were always
virtually unispecific, the species varying with the season. In winter,
at temperatures between 0� and 9�C, the diatom Skeletonema costatum
occurred. During most of the remaining part of the year, at water
temperatures of 100 - 250C, the diatom Phaeodactylum tricornutum, was
the persistent alga. During a brief period of about one month in
midsummer, when pond temperatures exceeded 250C, unidentified green
flagellates replaced the Phaeodactylum cultures. It is unlikely that
the species of algae present affect rate of algal production or nutrient
utilization, so this in not an important factor with respect to the
tertiary treatment role of the system. However, some species are well
recognized and documented as better food organisms than are others for
bivalve molluscs (3). Although Skeletonema is generally regarded as one
of the better shellfish foods, Phaeodactylum is variously reported as
poor to indifferent. The implications of that problem will be discussed
further below, but phytoplankton species control remained a chronic and
unresolved problem.

Two of the algae ponds could be heated by circulating their contents
through heat exchangers in the laboratory. These were operated at 150 -
200C throughout the winter when temperatures in the unheated ponds
ranged from 0� to 50 C. Surprisingly, there was no difference in algal
production between the heated and unheated ponds. Seasonal variations
in algal production of three- fourfold and even species succession and
dominance are apparently due to changes in incident solar radiation,
with temperature a second order factor, at least in winter. This is an
important finding, as it eliminates the need to consider heating an
extensive area of shallow algal ponds in winter in any commercial
application of the process in temperate latitudes. Unfortunately,
however, the algal culture must still be heated to at least 10�C and
preferentially 15 - 20�C before it can be utilized by the shellfish.

The continuous-flow cultures could be maintained for months at a
time with little or no maintenance. Gradually, the accumulation of
organic matter on the bottom and the development of a fringe of epiphytic
green algae (usually Enteromorpha) at the water's edge around the
periphery of the pond causes a reduction in algal production. This was
exacerbated if the sewage effluent contained significant amounts of
suspended solids. When that occurred, normally at intervals of 3-6
months, the ponds were drained, cleaned, sprayed with dilute sodium
hypochlorite, sundried, refilled, and reinoculated with an adjacent
culture. This required one or two days of effort per pond, and the new
culture could be brought on line into production in about four days.

355

At pond temperatures exceeding 15'C when Phaeodactylum was the
dominant alga in the cultures, one or more species of colorless
protozoan flagellates, roughly the same size as the Phaeodactylum
cells (i.e., 20-30~t in diameter) appeared in the cultures and fed
upon the diatoms. Unpredictably and very quickly the flagellate at
times proliferated throughout the culture and eliminated the algae.
Such cultures could be discarded and restarted, as described above,
but if left alone, the flagellate population quickly subsided,
presumably through lack of food, and the Phaeodactylum population
reestablished itself in about the same time (3-5 days) that it took
to start a new culture. Such predation did not occur often enough
to be a serious problem, but caused an undesirable interruption in
algal production when it did happen. No means of controlling the
predator~s) were found.

B. Bivalve mollusc culture,

Harvest from the phytoplankton pond cultures (equivalent in
volume to the daily turnover rate of the ponds) flowed by gravity
into respective cement raceways 40' long x 4' wide x 5' deep. At its
point of entry to the raceway, the algae culture was diluted with
coarse-filtered seawater at ratios ranging from I to 5 parts seawater
to I part culture, depending upon the season and other related factors.
Reasons for the dilution were: 1) to dilute the algal suspension to
the degree necessary for the shellfish to filter and assimilate the
food organisms most efficiently, a concentration of the order of l05
cells/ml; 2) to provide a more rapid flow of water through the raceway
to enhance shellfish feeding; 3) to prevent the accumulation of
metabolites of the animals, particularly ammonia, to toxic levels; and
4) through use of heated seawater when and as needed, to bring the
combined flow of algae and seawater to a temperature at which the
shellfish would feed and grow throughout the year. Phytoplankton will
grow equally well on heated and unheated pond cultures in winter, as
discussed above, but the unheated cultures must be heated to 100 - 200C
before they are presented to the animals.

The facility did not have the capacity to raise temperatures of
the combined algal culture-seawater mixture, at the desired flow rates,,
to levels above approximately i5'C in winter. Nor did it have the
capability of providing a range of different temperatures to the
raceway system while holding other factors (i.e., flow rates) constant.
Finally, there was no capacity to cool water, and solar heating of the
algal pond cultures together with the diluting seawater could result
in peak summer raceway temperatures of 25'C. It was therefore not
possible to control temperatures in the animal culture system beyond a
seasonal range of 150 - 250C. This led to some problems in attempting
to assess shellfish growth over long periods of time as a function of
other variables, such as food species, food concentration, flow rates,
etc.

356~

The algae culture-seawater mixture entered one end of the 40-foot
raceway and passed in a linear flow to the opposite end, where it entered
the adjacent seaweed-stocked raceway, for final "polishing" of the
effluent. Shellfish were stocked in wooden-frame, vexar-lined trays (mesh
size depending upon size of the shellfish) at an initial density, for the
1/2 - 1" seed, of 1,500 to 3,000 animals per tray, which was later to be
thinned appropriately as the bivalves grow (Fig. 2). The trays were
stacked vertically, 7-8 trays per stack, the raceways accommodating 8 such
stacks of trays, holding a total of some 150,000 seed shellfish. An
airline extended along the side of the raceway on the bottom to provide
aeration and vertical mixing of the water throughout its length. This was
found essential for mixing thoroughly the algae culture and diluting
seawater and preventing a stratified flow down the length of the raceway,
particularly in cold weather when heated seawater was used. In addition,
aeration was important in maintaining high levels of oxygen and low levels
of metabolites, particularly ammonia, everywhere in the raceway and
especially near the bottom.

The initial attempt at shellfish culture involving the stocking of
three raceways with 300,000 seed oysters (Crassostrea virginica) from
Flower Brothers Hatchery, Bayville, Long Island (NY) and 150,000 seed hard
clams (Mercenaria mercenaria) from Long Island Oyster Farms, Northport,
Long Island (NY) was largely unsuccessful. Neither species grew signifi-
cantly during the following 18 months and most of the oysters died. Two
possible explanations for this lack of success were suggested: 1) The
seed shellfish in question were stunted or otherwise inferior stocks or
they had suffered stress or injury during transport from their sources.
2) The phytoplankton grown in the mass algal cultures, predominantly
Phaeodactylum tricornutum during most of the year, was inferior and
unsuitable as food for the shellfish.

The first of those explanations was subsequently ruled out. New
stocks of American oysters were obtained from the same Long Island
hatchery that were newly-set, healthy, actively-growing seed obtained in
two separate lots during the spring. In addition, small lots of both
oysters and clams of the same species were obtained from other sources.
In no case did either species grow or even survive in the culture system.

Since Phaeodactylum and various green algae were already known to be
poor to indifferent foods for larval and very young juvenile clams and
oysters, the second explanation therefore appeared to be the correct one,
and success of the system appeared dependent upon the ability to control
the species and to grow other, more desirable food organisms in the mass
algal cultures.

At the same time these tentative conclusions were reached, however,
small numbers of juvenile Manila clams (Tapes japonica) and European
oysters (Ostrea edulis) were obtained. Both species survived well and
grew within the culture system and on the same food that failed to support
C. virginica and M. mercenaria. Tapes grew slowly, though apparently not
unusually so for the species (Fig. 3). Ostrea grew very rapidly, from 3.5
cm seed to 9.5 cm marketable adults in about five months (Fig. 4).

357

As a result of this experience new, larger lots of 0. edulis
were obtained from several sources and stocks of Japanese oysters
(Crassostrea gigas) were also obtained and introduced to the raceway
system. The results with 0. edulis were somewhat equivocal, some
growing well and others dying, but the reason for this is believed
to be damage or injury of some of the seed during shipment (i.e.,
from as far as the U.K.). The C. gigas stocks all grew well.

Thus, the earlier problem of the inability to control species
in the algal ponds and to produce phytoplankton suitable as food for
the indigenous species of oysters and clams, if not solved, appeared
to have been circumvented by use of exotic shellfish species capable
of utilizing the kinds of algae that could be mass produced. Very
preliminary results also indicated that the local bay scallop
(Argopecten irradians) may be included among the latter group, but
evaluation of that species was hindered by scarcity of seed stock.
The interesting question of why some bivalve species but not others
can subsist on the phytoplankton "weeds" remains to be answered.

Lack of research support for the project after the second year
prevented any quantitative evaluation of the system as a whole for
shellfish production. Smaller scale studies during an additional
year, with a different but reduced level of support, did permit a
study of the comparative growth of six species of bivalves using
phytoplankton produced in the wastewater-enriched cultures (4).

C. Seaweed culture.

Seaweeds were used in the polyculture system as a "polishing
step" to remove nutrients not initially assimilated by the phyto-
plankton and those put back into the culture system by excretion of
the shellfish and other animals and the decomposition of their solid
wastes. The objective was to achieve a nutrient-free final effluent
than would meet standards of tertiary sewage treatment at the same
time producing a crop of commercially valuable plants.

Seaweed research was restricted to red algae of several species
that are of existing or potential commercial value for their content
of agar or carrageenan. These included Chondrus crispus, Gracilaria
tikvahiae, Neoagardhiella baileyi, and Hypnea musciformis. Of these,
Gracilaria and Neoagardhiella proved most successful. The following
discussion concerns primarily the results obtained with Gracilaria
(Fig. 5).

As explained in the preceding section, water leaving the shell-
fish raceways passed through the adjacent raceway in the opposite
direction where it was exposed to suspended cultures of seaweed before
being discharged back to the ocean. The latter had the same dimen-
sions as the shellfish raceway (40' x 4' x 5' deep) but were modified
with a sloping plywood bottom with a depth ranging from two feet, on
the high side to the bottom (five feet) on the low side. An air line

358

Table 2. Mean seaweed production and nitrogen removal in effluent-enriched cultures, on

a seasonal basis. (Figures rounded).

Winter Spring-Fall Summer Maximum

Mean production

g dry weight/m2/day (ash-free) 3 5 13 16

Nitrogen removal

g/m-/day 0.1 0.2 .5 .6

lbs/acre/day (cultures 1 m deep) 0.9 1.8 4.5 5.4

Ecuivalent volume effluent treatedl

MGD/acre .004 .008 .022 .027

Area requirement

acres/MGD effluent treated 223 112 45 37

IAssuming 24 mg N/1 effluent or 200 lbs N/million gallons effluent.

359

on the bottom at the five-foot depth provided the vigorous
circulation needed to keep the seaweed in suspension and to bring it
continuously to the surface and to exposure to sunlight. The sloping
bottom eliminated a dead area in the circulation cell in the corner
opposite the air line, in which the seaweed would otherwise settle
and collect (Fig. 6).

Once a week, the seaweed population was harvested from the
raceways with dip nets, drained, and weighed.. Net production over
the previous week was removed, returning a constant starting biomass
of 50 kg/raceway. The routine was varied experimentally during the
year, but that figure was found empirically to be optimum for maximum
daily production, which ranged from a mean of 3 grams dry weight
(organic matter) m2/day in winter to 10 grams/m2/day in summer (dry
weight is 10 percent of wet weight and contains an average of
40 percent ash in Gracilaria tikvahiae).

Occasionally fouling organisms, in particular the green alga
Enteromorpha, invaded the seaweed cultures and grew epiphtically upon
the cultured species. Under extreme conditions, the cultures had to
be discarded. Epiphytic growth is probably the single greatest
problem in and constraint to commercial seaweed culture particularly
in the tropics and subtropics where conditions are otherwise ideal
for such practices. However, for reasons not fully understood, this
problem was never a critical one in the Woods Hole experiments.

During the second year, new experiments were initiated in which
seaweeds were grown alone, in a single-step waste recycling system,
using mixtures of seawater and secondary sewage effluent in a con-
tinuous flow-through mode of operation. A series of plywood tanks
8' x 6' x 3' painted with white epoxy were used in these experiments
(Fig. 7).

Maximum yields of Gracilaria of 16 grams ash-free dry weight/
m2/day were achieved for short periods of time in summer, while
average yields of 3 g/m2/day in winter and 12 g/m2/day in summer
were sustained over long periods of time. Table 2 shows yields and
nitrogen removal capacity for the seaweeds grown on sewage effluent
and seawater mixtures in the experimental tanks described above. As
in Table 1, the data have been extrapolated to show the potential
and areal requirement of such a system in nutrient removal per MGD
effluent. It may be seen that seaweed production is comparable to
and, in summer, slightly better than unicellular algae production.
However, because the seaweeds contain on the average less nitrogen
per unit of ash-free dry weight (4 percent for seaweeds and about
10 percent for unicellular algae), the equal or higher rate of growth
of seaweed is more than offset by its lower capacity for nitrogen
removal per unit growth.

360

In one experiment, three of the above seaweed tanks were operated
in series, with an input of 25 percent sewage effluent - 75 percent
seawater mixture introduced into the first tank and then passing through
the second and third tanks at flow rates equivalent to 50 percent of the
individual tank volume turnover per day. The three tanks were initially
stocked with 5,000, 3,000, and 1,000 grams respectively of Gracilaria,
and the growth increment allowed to accumulate during the one-month
period of the experiment. Inorganic nitrogen and phosphorus were moni-
tored in the water entering and leaving each of the tanks. The data
from this experiment is summarized in Table 3, where it may be seen that
the three tank cultures progressively removed 99 percent of the incoming
nitrogen. Nitrogen deficiency of the Gracilaria in the third tank was
evident both in its pale yellow coloration, in contrast to the deep
reddish-brown color of the plants in the first tank, and in its carbon:
nitrogen ratio, which was 28 in contrast to 10 in the first tank. This
has some practical significance, as the commercial product of the seaweeds
(agar in Gracilaria) is elaborated more rapidly and to a greater degree
in nitrogen-deficient plants. In a commercial seaweed culture application,
using a raceway or channel-type culture configuration with a linear flow
of water and nutrients, the seaweed should presumably be moved downstream
in the system, away from the source of nutrients, and harvested from the
far end following a period of exposure to nitrogen-free conditions.
Further evaluation of the production of the seaweeds and their hydro-
colloids in the wastewater recycling system is presented in a separate
report (5).

D. Nutrient removal efficiency of the system as a whole.

As pointed out earlier, algal pond cultures were operated during
the first year deliberately at nutrient (sewage effluent) concentrations
higher than could be completely utilized by the phytoplankton. This was
done to develop information on the maximum potential growth and nutrient
assimilative capacity of the algae under non-nutrient limited conditions.
The amount of nitrogen taken up by the algae from solution or the amount
contained in the algal harvest, by direct measurement, could then be
used to calculate the daily assimilative capacity of the system and
this, in turn, to calculate the daily input of sewage effluent per unit
area of algal pond for complete nitrogen removal. That information,
based on a year's observation, is presented in Table 1, also including
the comparable data for a seaweed-based tertiary treatment system.

The above data, interpreted in terms of the ESL pond culture
system, means that complete nitrogen removal could be expected in
winter operating at a 25 percent pond volume turnover per day with an
input of 10 percent sewage effluent and 90 percent seawater. In spring
and fall, the effluent strength can be increased to 20 percent or the
turnover rate doubled (50 percent), resulting in either case in doubling
the nutrient input rate. In summer, the system should be able to
assimilate completely the nitrogen from 30 percent effluent - 70 per-
cent seawater mix at 25 percent turnover, or a 10 percent effluent -
90 percent seawater at 75 percent turnover rate per day.

361

Table 3. Nitrogen removal in experimental seaweed (Gracilaria tikvahiae) tanks operated

in series under steady-state, continuous flow-conditions.

Tank No. Effluent N concentration % N removal Seaweed production C:N in seaweed
(cumulative) g/m2/day (ash-free)

1 0.96 60 3.4 10

2 0.07 77 2.5 12

3 0.02 99 1.2 28

Initial N concentration (input to Tank 1) = 2.41 ppm.

362

Since it is costly to pump seawater, the higher effluent concen-
tration at the lower exchange rate is the more economical mode of
operation. There is some evidence, however, that stability of the
cultures may be enhanced by low nutrient levels at high turnover rates,
so the costs of labor (for cleaning and restarting cultures) and of
building and operating stand-by cultures to provide for down-time may
exceed the cost of pumping additional seawater.

Table 4, shows typical steady-state mass flow of nitrogen through
the three-step system under late spring operating conditions as defined
above. Of the nitrogen (nitrate, nitrite, and ammonia) daily entering
the pond as sewage effluent (84 grams) and seawater (lg), over 98 per-
cent (83.4 g) was removed by the phytoplankton. The remaining 1.5g,
together with the algae, was fed to the shellfish raceway, where it was
mixed with twice its volume of seawater. Since the latter contained the
same concentration of inorganic nitrogen as the pond effluent (0.04 ppm),
the seawater contributed twice as much nitrogen as the effluent (total
4.5 g). To this, the shellfish raceway added 22.5 g of dissolved
inorganic nitrogen through excretion, decomposition, or other sources,
roughly 25 percent of the amount that entered the raceway as phytoplank-
ton. Of the total output of 27 g nitrogen from the shellfish raceway,
18 g were removed by the seaweeds, leaving a final residual of 9 grams,
10 percent of the initial input of the sewage effluent and seawater, for
a total removal efficiency of the system as a whole of 90 percent.
Since the seaweed removed two-thirds of the regenerated nitrogen, it
could be assumed that expansion of the seaweed culture by one-third
(from 160 ft2 to 240 ft2 in the pilot facility) would result in complete
nitrogen removal of the final effluent.

E. Culture of secondary animal crops.

Solid wastes (feces and pseudofeces) produced by the shellfish
and/or uneaten phytoplankton cells which settle out from suspension in
the shellfish raceways provided sources of food for large quantities of
several species of small, invertebrate detritovores that presumably
entered the system as larvae in the coarse-filtered seawater use to
dilute the phytoplankton pond harvest. Prominent among such inverte-
brates were amphipods (Corophium, Jassa, and Gammarus), polychaetes
(Capitella capitata), bryozoans, tunicates, and mussels. This small
invertebrate fauna served the dual purpose of preventing the accumula-
tion of solid organic wastes in the raceways and providing a source of
food for secondary crops of carnivores or omnivores of potential
commercial value. The latter included the American lobster (Homarus
americanus) and the winter or blackback flounder (Pseudopleuronectes
americanus) (Table 5).

In July, 474 juvenile (0 to 1 year class) flounder were collected
locally and stocked in one of the oyster raceways. Their size distri-
bution was, of course, bimodal for the two-year classes, but averaged
7.0 cm. In October, the raceway was drained and 124 fish recovered,
averaging 11.0 cm in length. The following April, 69 fish were recovered,

363

Table 4. Mass flow of inorganic nitrogen (ammonia, nitrite, and nitrate)

through the phytoplankton-oyster-seaweed system.

grams N/day

1. Phytoplankton pond input

sewage effluent 84

seawater 1 85

2. Phytoplankton pond output 1.5

3. Shellfish raceway input

phytoplankton pond harvest 1.5

seawater 3.0 4.5

4. Shellfish raceway output 27

(= seaweed raceway input)

5. Seaweed raceway output

(final effluent from system) 9.4

Total N removal efficiency (including seawater) 89.3%

Effluent N removal efficiency 93.6%

364

Table 5. Growth and survival of winter flounder and American lobsters in

oyster raceways.

Winter flounder (Pseudopleuronectes americanus)
Days Number % survival Size (mm)

0 474 ---- 70

120 99 21 110

300 69 14.5 167

American lobster (Homarus americanus)
Days Number % survival Size (mm)

0 390 ---- 9.0

90 256 66 13.4

240 124 32 25.0

Carapace length.

365

averaging 16.75 cm in length. The surviving fish thus more than
doubled in size in 9 months. If the observed linear growth rate were
to continue, the fish would reach a marketable size of 25 cm (1/2 -I
I lb) in another 9 months, or 18 months from the time of stocking as
juveniles.

Egg-bearing lobsters were obtained from commercial fisherman, by
special permit, and were held in the laboratory until the eggs hatched
(i.e., in spring, when water temperatures reach 150 - 20'C). The
larvae were transferred to specially-constructed larval rearing tanks
where they were fed live or frozen brine shrimp (Artemia salina).
After metamorphosis to juvenile lobsters (10 - 14 days), they were
segregated into small containers, to prevent cannibalism, and fed the
same food until they had molted an additional 3 - 4 times and attained
a mean size of 9 mm carapace length and 0.18 grams. A total of 390 of
these lobsters were then stocked in September in segregated (screened-
off) portions of two oyster raceways, each group together with two
stacks (16 trays) of oysters. The following April, a total of 124
lobsters were recovered which had a mean size of 25 mm carapace length
and a mean weight of 18 grams. These ranged widely, however, in their
size distribution, from 10 to 52 mm carapace length. The larger
individuals, some 150 mm total length, attained a size in eight months
that is not reached by wild lobsters in New England in less than three
years, and is comparable to the best growth obtained with segregated
lobsters held in captivity at elevated temperatures and fed artificially.

366

References

1. Ryther, J. H. and W. M. Dunstan. 1971. Nitrogen, phosphorus and
eutrophication of the coastal marine environment. Science 171:
1008-1013.

2. Goldman, J. C., K. R. Tenore and H. I. Stanley. 1974. Inorganic
nitrogen removal in a combined tertiary treatment-marine aquaculture
system. Part II. Algal bioassays. Water Research 8: 55-59.

3. Ryther, J. H. and J. C. Goldman. 1975. Microorganisms as food in
mariculture. Annual Reviews of Microbiology 29: 429-443.

4. Mann, R. and J. H. Ryther. 1977. Growth of six species of bivalve
molluscs in a waste recycling-aquaculture system. Aquaculture 11:
231-245.

5. DeBoer, J. A. and J. H. Ryther. 1978. Potential yields from a
waste-recycling algal mariculture system. In R. Krauss, Ed. The
Marine Plant Biomass of the Pacific Northwest Coast. Oregon State
Univ. Press. 397 pp.

367

Figure Legends

Figure 1. Environmental Systems Laboratory, Woods Hole Oceanographic
Institution.

Figure 2. Wooden frame, vexar-mesh trays with seed oysters in shell-
fish raceway.

Figure 3, Growth of Tapes japonica after five months.

Figure 4. Growth of Ostrea edulis after five months.

Figure 5. The red seaweed Gracilaria tikvahiae grown in ESL raceway
system.

Figure 6. The ESL raceway system with shellfish raceways covered and
seaweed raceways exposed.

Figure 7. Plywood tanks used for growing seaweeds directly on sewage
effluent.

368

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THE SOLAR AQUACELL SYSTEM FOR PRIMARY, SECONDARY
OR ADVANCED TREATMENT OF WASTEWATERS

William C. Stewart, Director of Research and Development, Solar
AquaSystems, Inc.*

Steven A. Serfling, President, Solar AquaSystems, Inc.*

The Solar AquaCell process is an aquaculturally derived wastewater
treatment system which integrates proven wastewater treatment elements
to allow greater process control, higher quality effluent, and reduced
land area as compared to conventional wastewater lagoons. Three AquaCell
pond systems, anaerobic, facultative, and aerobic, all containing high
surface area bio-film devices, can be used in series to achieve primary,
secondary and/or advanced treatment, respectively. Three years of
pilot scale demonstrations have shown that conservative design practices
can be used while also achieving reduced construction, operation and
maintenance costs, minimal solids handling, low energy demand, and low
operator skill requirements. The use of a multiple series of controlled
cells allows a high degree of design and operational flexibility for
meeting various effluent quality objectives. The City of Hercules'
Solar AquaCell Treatment System is also described.

* P.O. Box 88, Encinitas, California 92024

377

INTRODUCTION

Reliability and stability in meeting discharge standards must be
the primary criterium for every wastewater treatment process. In cases
where the effluent is to be discharged, maintenance of these standards
is critical in preventing degradation of receiving waters and ground-
water supplies.
It has been estimated by the U.S. Environmental Protection Agency
that conventional secondary quality treatment plants in the United
States are failing to meet discharge criteria 30-50% of the time (1-2).
Designers of these processes blame municipalities and correlate the
lack of reliability and stability primarily on inadequate operation and
maintenance budgets and poor operator training (3). Correction is said
to require an increased financial commitment from the municipality
managing the treatment plant. However,, we must face the fact that be-
cause of the changing economic conditions, additional 0 & 14 support
from an already hard-pressed local government will be difficult to find.
Also, the increasing cost of energy, coupled with the high energy de-
mand of most wastewater treatment processes is adding a serious burden
to operating costs. Thus, design criteria for new wastewater treatment
processes must also include low 0 & 14, simplicity of operation, and low
net energy requirements.
In many areas of the world, including parts of the United States,
water supplies are not adequate to meet projected, and in some cases,
even present demand. As recycling and/or reuse of treated wastewater
becomes economically advantageous, the reliability and stability of
treatment processes becomes even more critical to prevent release of
disease or toxic materials (4). Attempts to provide cost effective
advanced treatment of wastewater for reuse by modification of conven-
tional systems have not been successful, primarily due to excessively
high capital and operation and maintenance costs and the complexity
of the process trains to achieve the necessary reliability (5-6). As
a result of these failures, the U.S. Environmental Protection Agency
is now requiring special scrutiny of all AWT projects (6). Thus,
despite the potential and need for reuse of wastewaters, recycling has
suffered a severe setback due to the application of an inappropriate
technology.
In addition to recycling of water, the recycling of the nutrients
from wastewater appears necessary in the very near future if food prices
and agricultural productivity are to meet population needs. The pro-
duction of expensive, petroleum derived fertilizers while discharging
valuable nitrogen and phosphorous laden wastewater cannot make sense
for long. For these and additional reasons, there is a growing interest
in alternative technologies for wastewater treatment. Among those which
have demonstrated excellent potential for meeting the new criteria are
aquaculture and aquaculture-derived wastewater treatment systems.
The major advantages of most aquaculture treatment processes are
low operation and maintenance costs, simplicity of operation, and poten-,
tially greater reliability and stability. Henderson and Wert (7) have
calculated that aquaculture wastewater treatment systems can save up to
90% of the total life cycle treatment costs when compared to conven-
tional technologies. Duffer and Moyer (8) provide an excellent review
of the status and potential of aquaculture processes for municipal

379

wastewater treatment. For wastewater reuse and/or recycling purposes,
managed aquaculture systems offer the advantages of high dilution of
toxic wastes and longer retention times to reduce upset potential.
Potentially toxic wastes can also be removed without the addition of
chemicals (9-10), thus reducing operation costs. However, the chief
limitation of most aquaculture type processes has been high land
area requirements and/or the lack of process control for achieving
advanced treatment objectives.
In order to provide an alternative between the extremes of existing
high energy conventional technology and simple, low cost, algal lagoon
methods, Solar AquaSystems, Inc. has developed and extensively tested
over the past 4-year period, a high rate, controlled environment aqua-
culture wastewater treatment process called the Solar AquaCell System.

THE SOLAR AQUACELL SYSTEM

The basic design parameters of the Solar AquaCell System have been
described previously (11). The design principles of the AquaCell
system are based on an integration of the best features of lagoon or
aquaculture systems (i.e. low operation and maintenance costs, low
energy requirements, high dilution factors, toxin removal capabilities,
nutrient recovery), with the reduced land area requirements, increased
process control, and advanced treatment capability of conventional,
higher technology systems.
The AquaCell process consists of an integration of the following
basic elements: (Fig. 1)
1. a series of multicell lagoons.
2. a diffused aeration system for maintaining proper dissolved
oxygen concentrations, and to provide for gentle stirring and partial
mixing of the wastewater past the aquatic plant surface area and BioWeb
substrates.
3. high surface area fixed-film substrates (activated BioWeb
substrates) to provide habitat for the biofilm and associated detriti-
yore community.
4. the use of floating aquatic macrophytes, particularly water
hyacinths and duckweeds, for achieving advanced treatment and recovery
of nutrients.
5. tensile structure greenhouse pond cover to provide cost
effective insulation for capture of solar heat in cooler climates and
to reduce evaporative water losses.
6. a simple solar heat exchange system for transferring solar
energy from the air phase to the water phase in order to increase pond
temperature, metabolic rates, and thus treatment efficiency.
The function of each component is described in further detail in
the following section.

AquaCell Component Description

1. The Multicell Lagoon Process
The use of lagoons for wastewater treatment processes is a proven
and well documented technology (12). In these applications, lagoons
offer the following advantages:

380.

FIGURE 1

SECTION VIEW - SOLAR AQUACELL SYSTEM

SOLAR ENERGY DOUBLE POLYETHYLENE
AIR INFLATED ROOF

WATER HYACINTHS
OUCKWEEDS ,

N/1"

zLA _Y7 -

$~5_Itt"774," Al- / i,

//';-'X DIFFUSED BIO-WEB SUBSTRATES AERATION .k.'[
"/ " - AERATION FOR ATTACHED PROVIDES
CONCRETE POST MICROORGANISMS GENTLE MIXING SLUDGE
& FOOTING DIGESTS
ANAEROB CALLY

381

A. Lagoons are relatively inexpensive to construct and maintain
and have a potentially greater life cycle than concrete tanks. Properly
designed and sealed, leakage and consequent groundwater contamination
problems from lagoons can be avoided.
B. Lagoons offer major safety factors for wastewater treatment.
Conventional biological wastewater treatment designs have retention
times of only a few hours. Consequently, toxic shock loads receive
little initial dilution, and can cause poisoning and cessation of
biological activity with subsequent discharge of high amounts of un-
treated or poorly treated wastewater. Lagoon systems, with their
longer retention times and greater volumes, provide rapid and adequate
dilution of toxic materials with consequent protection of the biolog-
ical treatment components of the system. In addition, the extended
retention times provide more complete removal of toxic materials and
pathogens.
Disadvantages of conventional lagoon systems include high land
area requirements and, because of the high water surface area, re-
duced control over the treatment process, In addition, problems with
algal growth within lagoons create difficulties in meeting effluent
requirements for suspended solids and reduces seasonal reliability.
The Solar AquaCell system uses a series of lagoons modified for
smaller size and improved hydraulic design. This approach is made
possible by the use of high surface area BioWeb substrates and aeration
within the lagoon as discussed below.

2. Diffused Aeration
The shallow AquaCell lagoon process is designed to use a low
energy, low pressure, high volume diffused aeration system for the
purpose of maintaining proper dissolved oxygen concentrations through-
out the system, and, providing gentle stirring and partial mixing of
the wastewater past the BioWeb substrates and aquatic plant root sur-
face area. Air consumption of the Solar AquaCell system is signifi-
cantly reduced in comparison to conventional processes through imple-
mentation of the following strategies:
A. Use of the anaerobic AquaCell for initial treatment of raw
wastewater. The BOD loading on the subsequent aerated ponds can be
reduced 50-70%.
B. Use of a facultative AquaCell following anaerobic pretreat-
ment. Since the facultative cell is not subject to shock loadings of
raw wastewater, and is handling a reduced BOD and suspended solids
load, aeration requirements in this cell are reduced as compared to
conventional practice. In addition, the maintenance of an anaerobic
bottom layer in the facultative pond bottom provides for stabilization
of settled organics without the consumption of additional energy.

3. BioWeb Substrates
The use of biologically active substrates or bio-films, to provide
increased surface area for microbial growth is standard practice in
conventional biological treatment processes. For example, activated
sludge plants and oxidation ditches use suspended particles of sludge
to provide this increased surface area; trickling filters use rock,
redwood, or plastic media; rotating biological contractors use plastic
disks rotated through the wastewater stream, all for the purpose of

382

growing bacteria and associated microorganisms.
Solar AquaSystems, Inc. has pioneered the use of vertically
oriented bio-films for use in lagoon type processes. Four types of
substrates have been developed to optimize treatment throughout the
process train. For example, flat sheet bio-film appears to optimize
conditions for BOD reduction in high loading conditions, while mesh
type bio-films in various configurations optimize conditions f~r
nitrification and denitrification. Design factors are 2-3 ft. of
surface area per gallon treated for secondary treatment while 4-6 sq.
ft./gpd is required for various levels of tertiary treatment (11).
Because of the relatively low cost of BioWeb substrates, it is econom-
ical to design lagoon processes with much higher bio-film surface area
to loading rate ratios and with longer retention times than found in
conventional bio-film processes, thus resulting in a more conservative
design than conventional technologies. Additional advantages of the
Solar AquaSystems" BioWeb include:
A. No structures are required to support the BioWeb, since it is a
low density floating material and only needs to be anchored at the
bottom. It can be easily added to lagoon systems without the cost of
additional components.
B. Reduction of BOD and suspended solids is achieved also by
physical means, with the BioWeb substrates acting as a barrier to in-
crease coagulation and sedimentation of the suspended organics, which
are then digested anaerobically on the pond bottom.
C. The vertically suspended, buoyant BioWeb substrates maintain
the bacterial film in suspension without the need for energy for
aeration as is required for the activated sludge process and oxidation
ditches,or for movement through the water phase as is required for
rotating biological contactors. Similarly, the trickling filter re-
quires high pumping costs to lift and recycle sewage through the filter
media.
D. The BioWeb substrates also provide extensive habitats for
grazing organisms which consume, concentrate, and metabolize the
organic and inorganic detritus material adhering on the BioWeb sub-
strates. Because of their flexible nature and vertical orientation,
BioWeb substrates are self-cleaning, thus eliminating blockage problems.
For this reason, BioWeb equipped systems are capable of treating higher
loading rates than conventional biofilm processes.
E. The BioDeb substrates act as channeling devices to minimize
short circuiting in lagoons and improve plug flow conditions for
optimal treatment efficiency.

4. Floating Aquatic Macrophytes
To date, the most promising aquaculture wastewater treatment
systems have used floating aquatic macrophytes, primarily water hya-
cinths and duckweeds. These plants offer the following advantages
for treating wastewaters,
A. Stability and hardiness - extensive studies by Wolverton (9)
with water hyacinths and Hillman and Culley (13), and Harvey and Fox
(14) with duckweeds have demonstrated that both plants are very stable
and hardy organisms that can survive and rapidly multiply under varying
environmental conditions. In fact, both plants have been shown to

383

greatly increase both average and total productivity when cultured in
wastewater treatment ponds. They can tolerate widely fluctuating
nutrient loading rates, solar input, fluctuations in water chemistry
such as pH, carbon dioxide, alkalinity, and are not affected by toxic
compounds (heavy metals, chlorinated hydrocarbons, phenols, etc.) at
concentrations typical of municipal wastewaters. Studies by Wolverton
(9) have shown that water hyacinths can be used for concentration, re-
moval, and potential recycling of a variety of heavymetals occurring
in many industrial effluents.
B. Provide shade to prevent algal growth - floating aquatic macro-
phytes eliminate high effluent levels of suspended solids and BOD
caused by algal cells because the sunlight penetrating through the
plant fronds is insufficient to allow significant phytoplankton growth.
C. Ease of harvest - the aquatic macrophytes are relatively easy
to harvest compared to unicellular algae. Duckweeds can be removed
by a surface skimming device as part of the pond overflow mechanism.
Hyacinths, when harvested on a regular basis, can be removed by an in-
pond harvesting boat, chopped, and pumped as a slurry to the reuse
area.
D. High reuse potential - water hyacinths and duckweeds offer
numerous reuse possibilities, including high protein animal feeds,
conversion to rich organic compost or fertilizer, or conversion to
methane gas or methanol. Water hyacinths grown in sewage lagoons
typically average 20% protein (9), while duckweeds have been shown to
average over 40% protein (13). Studies by Wolverton (9) and Lecuyer
and Martin (15) have demonstrated that one acre of water hyacinths can
produce an average of 200-300,000 cubic feet of methane gas per year.
E. Advanced tertiary quality effluent can be economically
achieved - due to the stability, high productivity, shading, and
relative ease of harvest, floating aquatic macrophytes can contribute to
advanced tertiary quality water with relatively little capital or
operating costs. The plants convert dissolved nutrients into a fixed
biomass which is stable until harvested, and does not recycle or return
to the effluent or lagoon bottom to create problems at a later time.
This controlled aquaculture process does not require the expensive
energy, chemicals, or maintenance costs which are typical of conven-
tional advanced wastewater treatment systems. In addition, capital
costs can be significantly lower.

5. Tensile Structure Greenhouse Covered Ponds
The organisms involved in all biological wastewater treatment
processes (i.e. bacteria, protozoans, fungi, rotifers, amphipods,
macrophytes, algae, etc.) are poikiothermal, that is, their metabolic
rate follows the ambient temperature of their environment. Generally,
changes in their metabolic rate, and consequently, the rate of waste-
water treatment at varying temperatures, can be estimated by the
van't Hoff-Arrhenius equation. This states that for every 100 C change
in temperature, the reaction changes by a factor of 2. Thus, a biolog-
ical treatment process operating at 20�C will function at twice the
effectiveness of one operated at 10'C, or conversely, require one-half
the treatment area.
In order to take advantage of the normally high temperatures of

384

incoming wastewater, which vary from 10 to 21.19C (1,6), the Solar
AquaCell system is designed to utilize relatively low cost, tensile
structure type greenhouses specifically designed for covering waste-
water ponds. Advantages of using these structures include:
A. Reduced land area due to increased operating temperatures,
especially in areas with moderate to severe winters. Combined with
solar heat transfer (see following section 6), which can be consider-
able even on cloudy days, it is possible for a greenhouse covered pond
system in northern climates to have average operating temperatures of
12-17'C during a four-day retention period, thus maintaining system
reliability and stability while reducing land area costs.
B. Year-round process stability, since most aquatic plants,
particularly water hyacinths, cannot survive or grow if exposed during
winter seasons in most temperate climates. Use of the greenhouse pond
cover permits maintenance of water temperatures necessary for continual
growth of most macrophytes in areas of moderate winter temperatures.
Duckweeds, in particular, survive naturally in cold climates and, by
using greenhouse covers, are capable of growth throughout the year in
a cold climate treatment system.
C. Increases in total dissolved solids due to evaporation is a
problem in arid regions. 'Use of macrophytes for wastewater treatment
increases the rate of evapotranspiration still further. Use of green-
house covers over the treatment ponds controls evapotranspiration and
prevents the increase in TDS in the treated wastewater. Thus, the
greenhouse pond cover can be particularly cost effective where water
is a valuable commodity.
In cold-climate situations, snow loads are not a serious con-
cern because the warm temperatures within the greenhouse (including
between the two plastic roof membranes), and in the pond, which acts
as a giant heat reservoir, quickly melt any snow accumulating on the
roof membrane. Greenhouses are commonly used in the hydroponic veg-
etable and decorative plant industry in northern climates without
experiencing serious snow load problems. Greenhouse systems utilizing
double layer, air inflated membrane roofs have particular advantages
in retaining pond heat. It has been demonstrated that such roofs can
reduce heat loss to 50% of greenhouses with single layer roof glazings
consisting of glass, fiberglass, or polyethelene (17).

6. Solar Heat Exchange and Sprayer System
The solar heat exchange system, used in conjunction with the green-
house covers, transfers solar energy from the air phase inside the
greenhouse into the water phase in the treatment ponds. This system
utilizes low volume misting nozzles and a thermostatically controlled
pump to recycle treated, disinfected water from the final effluent.
It has proven its effectiveness in increasing water temperatures as-
well as aquatic plant vigor in both wastewater and aquacultural appli-
cations at the Solar AquaSystems laboratories.

RESULTS OF PILOT STUDIES TO DATE

Description of Demonstration Facility

385,

In order to develop, test and fine tune the AquaCell process,
Solar AquaSystems, Inc. has constructed and operated two facilities
in the San Diego area, The first, located in Solana Beach, was oper-
able on an intermittant basis from September, 1976 to March, 1978.
At this first facility, the Solar AquaCell proved capable of treating
sewage to a tertiary quality within 4-6 days retention time under
varying nutrient loading conditions. Performance results from testing
at the Solana Beach facility are provided in a previous publication (11).
In June, 1978, a new demonstration and testing facility was constructed
at the San Elijo treatment plant in Cardiff, California. The San Elijo
treatment plant is operated by the County of San3Diego and provides
primary treatment and ocean discharge of 7,600 m /day (2 mgd) of
domestic sewage. The Solar AquaCell facility at Cardiff, which is
currently in operation, consists of a 3-stage AquaCell system containing
a series of five cells operated by gravity flow (Fig. 2 ). It was de-
signed to approximate full scale AquaCell design parameters in terms
of surface to volume ratios, waste loading rates, aeration rates,
aquatic plant cover, etc., and to incorporate various design improve-
ments based on experience at the Solana Beach facility. The Cardiff
demonstration system has been treating an average of 11,350 liters
(3,000 gpd) per day since July, 1978.
The first or primary treatment stage (Cells 1 & 2) is operated
anaerobically and designed for advanced primary treatment of raw
sewage. The first cell acts as a sedimentation basin, with upflow
percolation of incoming raw wastewater through an actively respiring
sludge layer. The volume of this cell is approximately 4,500 liters.
The second cell contains high density, vertically suspended BioWeb
substrates which function as fixed bio-films to further reduce BOD,
TSS, and to optimize methane production. Both anaerobic primary cells
have floating rubber covers for methane gas collection, odor control
and heat retention. Total retention time for the two-stage anaerobic
AquaCell averages 14 hours (6 hrs. - Stage 1; 8 hrs. - Stage 2).
The following secondary and tertiary treatment AquaCells consist
of three equally sized cells, each 2.4 meters wide, 4 meters long and
1.7 meters deep of approximately 16,000 liter capacity each. These
three tanks are plumbed with header pipes at each end to evenly dis-
tribute flows and minimize short circuiting. The influent and effluent
piping to each tank is plumbed to also allow either parallel or series
flow operations but to date has only been operated as series flow.
Diffused aeration is provided by a small air compressor, (0.5 hp), and
submerged air diffuser pipes extending the length of each aerated cell.
The first aerated cell (Cell #3) also contains a 0.06 hp surface
aerator.
The secondary treatment cell (Cell #3) is operated under faculta-
tive conditions to allow further sedimentation and anaerobic digestion
in the benthic layer to reduce overall energy requirements. No plant
cover is used in this facultative AquaCell1 Treatment is achieved
through sedimentation and microbial activity provided by the BioWeb
substrates, and maintenance of dissolved oxygen at 1 to 3 ppm.
Cells 4 and 5 of this series are operated to achieve various levels
of advanced tertiary treatment. In addition to the submerged BioWeb
substrates, Cells 4 and 5 also contain floating aquatic plants, either

.386

FIGURE 2

PROCESS FLOW DIAGRAM-SOLAR AQUACELL DEMONSTRATION UNIT

Cardiff, California

2-STAGE ANAEROBIC CELL
3 Sedimentation, Methane generation & AEROBIC AQUACELL 1 AEROBIC AQUACELL 2 AEROBIC AQUACELL 3
digestion & BOD. COD reduction A (Facultative Stage)
acid formation stage Gas vent
stage /Floating cover Floating Aquatic Plants
IckAWd Or (Duckweeds, hyacinths, water ferns),
SCWAGE ~l~B B ~substrates for methanoge Slo
INFLUERNT ;� - : - - : : ' -' -::TbSand Filter

Polished
Upflow percolation XActlvated Bio-Web Substrates / Aeration pipe effluent
through sludge. Self-cleaning blo-film and diffusers
substrates for methanogenic
bacteria

water hyacinths (Eichornia crassipes2 and/or duckweeds (Lemna sp.,
Spirodela sp., Wolffia spp.) and are maintained under aerobic condi-
tions with 3-6 ppm of dissolved oxygen. The plants function to shade
out growth of planktonic algae, remove nutrients, trap suspended solids,
and collect and remove a portion of the invertebrate food chain when
harvested. The floating plants provide the additional advantage of
resource recovery, since they are a convenient method for converting
dissolved and particulate wastes into either methane gas, organic
compost for soil application, or animal feeds. However, previous
studies (18) have shown that the BioWeb substrates are responsible for
80% or more of the treatment that takes &lace in these cells. The slow
sand filter (4-8 liters per minute per m ) at the effluent end of Cell
#5 functions to trap any invertebrate organisms, aquatic plant debris,
or resuspended detritus exiting through the effluent pipe. Total re-
tention time for the five cell sXstem averages 4.8 days at the 11,350
liter/day flow rate. Secondary treatment levels are achieved with a
2-day retention time (anaerobic cells 1 and 2 and facultative cell 3).
The entire five cell series is enclosed within a greenhouse which
insulates against heat loss while collecting solar heat in order to
maintain higher winter operating temperatues. Water misting nozzles
(solar heat exchange system) above cells 4 and 5 spray treated effluent
water to transfer solar heat into the AquaCells, increase aquatic plant
vigor, and protect plants from overheating during summer periods.
The facility at Cardiff has been utilized as both a demonstration
and research laboratory, testing the effect of various levels of aera-
tion, harvesting and management schedules, sludge deposition and di-
gestion rates, BioWeb material and form, etc. Due to its small size,
the facility can be looked upon as a worst case condition, since aqua-
culture processes in general attain greater stability through greater
size.

Results

Data collection and analysis were performed by the University of
San Diego Environmental Studies Laboratory, funded in part by a con-
tract from the U.S, Department of Interior, Office of Water Research
and Technology (19). In the period from July 14, 1978 to August 31,
1979, a total of 440 suspended solids, 339 BOD, 497 ammonia, 388
nitrite, 481 nitrate, and 271 turbidity measurements were taken on a
regular basis. Additional measurements of dissolved oxygen, pH, COD,
TOC, coliform, heavy metal, chlorinated hydrocarbon, and other tests
were also performed.
Data showing performance analysis of the Cardiff AquaCell Demon-
stration Laboratory has been presented previously by Serfling and
Alsten (11), and Stewart, et al. (20) and will not be covered in its
entirety in this paper. However, additional, more current data,
especially that concerning the anaerobic AquaCell and the attainment
of secondary treatment by use of the anaerobic and facultative AquaCells
in series without aquatic plants will be discussed.

388

Primary Treatment

The anaerobic AquaCell at Cardiff, with a six-hour retention time
in the first stage and an eight-hour retention time in the second or
bio-film stage, has been achieving an average BOD removal of 50%
(standard deviation - 27.7) and a suspended solids removal of 88.7%
(standard deviation - 12.6) over the ten month period for which data
is presented (Table 1). Raw influent BOD levels during this time have
ranged between 480 and 130 ppm with a median value of 218.4 ppm.
Suspended solids in the raw influent have ranged between 628 and 140 ppm
with a median value of 247.9 ppm. In addition, COD reduction has aver-
aged 72.6%, turbidity - 49.6%, TOC - 81.4% and fat and oil reduction -
58%. The pH of the influent raw wastewater has varied between 6.8 and
7.9 with a mean of 7.3. Effluent pH has ranged between 6.6 and 7.2
with a mean of 6.9. These treatment levels have been achieved through
use of a completely passive system requiring no energy input or moving
parts, and have been remarkably stable.

Secondary Treatment Using the Anaerobic - Facultative AquaCell
Combination

Effluent from the Anaerobic AquaCell flows next into the facul-
tative AquaCell for secondary level treatment (see Figure 2 for
process train). This aerated cell has a 1.4 day retention time and
contains no aquatic plant cover, treatment being entirely by micro-
organisms on the BioWeb surface. Tests showed that floating aquatic
plants in this AquaCell could improve treatment slightly, but surface
oxygen exchange was also impaired, requiring increased energy costs
for aeration. Suspended algae blooms are not a problem in this cell
without the floating macrophyte cover for shade due to the short re-
tention time. Results showing the performance of the combined primary
and secondary AquaCells is presented in Table 1 and Figures 3-5.
Figure 3 is a graphical representation of Table 1 data for BOD, sus-
pended solids and turbidity and removal for the anaerobic-facultative
AquaCell combination. Figures 4 and 5 show average monthly values for
influent raw wastewater, anaerobic AquaCell effluent and facultative
AquaCell effluent for BOD and suspended solids respectively. As can
be seen, secondary discharge standards have been achieved on a reliable
basis for the ten-month period represented.
BOD loading rates for the anaerobic AquaCell were equivalent to a
high range of 5230 kg/ha/day (4,667 lbs/acre/day), and a low of 1,200
kg/ha/day (1,072 lbs/acre/day) with a mean value of 2,380 kg/ha/day
(2,128 lbs/acre/day). As expected, the higher the BOD loading applied
to the anaerobic AquaCell, the greater the percentage of overall removal,
a phenomenon characteristic of anaerobic processes in general.
BOD loading rates for the facultative AquaCell have been recorded
as high as 2068 kg/ha/day (1,843 lbs/acre/day) with secondary treat-
ment levels still being attained. This performance is due to the high
bio-film surface area which accelerates both sedimentation of particu-
late BOD and aerobic metabolism of dissolved BOD material.

389

Table 1

Treatment Performance of Primary (anaerobic) and
Secondary (facultative) AquaCells,
Without Use of Aquatic Plants
(Nov., 1978 - August, 1979)

PRIMARY SECONDARY
TOTAL %
RAW ANAEROBIC % REMOVAL FACULTATIVE REMOVAL
SEWAGE AQUACELL ANAEROBIC AQUACELL ANAEROBIC AND
PARAMETER INFLUENT EFFLUENT() AQUACELL E FFLUEN T AU LATIVE
(a) EFFLUENT AQUACELLS (b)

BOD (mg/L) 218.4 109.0 50.0% 15.7 92.8%

S.S. (mg/L) 247.9 27.9 88.7% 11.9 95.2%

COD (mg/L) 518.0 142.0 72.6% 61.0 88.2%

Turbidity 205.0 103.4 49.6% 34.2 83.3%
(NTU)

TOC (mg/L) 271.6 67.5 75.1% 32.7 88.0%

pH (average 7.4 6.9 7.3
means)

Ammonia * 40.9 34.0 16.9% 28.9 29.3%
(mg/L)

* The secondary or facultative AquaCell, in this case, is not intended to achieve
complete nitrification. In situations where an advanced secondary level of
treatment with complete nitrification is required, increased aeration rates
and slightly increased retention time will provide this level of treatment.

(a) 14 hr. retention time (6 hr. Stage 1; 8 hr. Stage 2).

(b) 2 day retention time (combined).

390

FIG, 3
COMBINED TREATMENT PERFORMANCE OF PRIMARY (ANAEROBIC)
AND SECONDARY (FACULTATIVE) AQUACELLS
250

200-

Anaerobic AquaCell - Anaerobic-Facultative
Iz I \ \Effluent AquaCell Effluent

u 100-

EPA Secondary
Oischarge Standards
(BOD & S.S. only)

50-

40- Turbidity

30.

20- BOD

S.S.
10-

0
0 14 HR. i DAY 2 Days
Raw Sewage RETENTION TIME
:nfluent

391

FIG, 4

BIOCHEMICAL OXYGEN DEMAND REMOVAL BY PRIMARY & SECONDARY AQUACELLS

u-u Raw Influent

H-0 Anaerobic Effluent (14 hr. retention)

300 - Anaerobic-Facultative Effluent
~300 (2 day retention)

Ez
z 200
CD w

60 EPA Secondary
Discharge Standards
I 40

, ...............................................................................................................................................

1978 1979
1978 1979

FIG, 5

SUSPENDED SOLIDS REMOVAL BY PRIMARY 8 SECONDARY AQUACELLS

a-.-__ Raw Influent

H ---- Anaerobic Effluent (14 hr. retention)
300-
*-* Anaerobic-Facultative Effluent (2 day retention)

t-
0

-J

> 200-
z

100 -
U-
z

o 80

60- EPA Secondary
Discharge Standards
40-

20 D J

Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug.
1978 1979

Sludge Stabilization and Reduction

The first stage of the anaerobic AquaCell achieved a sludge re-
duction rate of 85-90% for the ten-month period during which the
sludge was retained in the system. These high reduction rates are
due to (1) mixing, high substrate contact, and constant reinnoculation
by the incoming wastewater as it flows upward through the sludge layer,
and (2) the long solids retention times made possible in a cost-
effective manner by this type of construction and design, in contrast
to conventional primary sedimentation and sludge digestion technology.
These high solids reduction rates are within the range of 84% reduction
reported by Coulter, et al. (21) for their pilot scale upflow digester.
No occurrance of scum buildup has been experienced during the ten-month
period. Samples of sludge removed by a diaphragm pump from Stage 1
showed easy pumping and flow characteristics and excellent dewatering
capabilities. Samples placed on single media sand drying beds were
completely dewatered within one week. The pumped sludge also had
little odor. Simpson (22) and Pretorius (23) also reported very good
dewatering properties for sludge removal from their upflow anaerobic
digesters. Analysis of four aliquots of sludge taken at different
times showed an average moisture content of 91%. Ash content was 53%.
Nutrient content was low, representative values being 0.90% nitrogen,
0.39% phosphorus, and 0.04% potassium, due to the long retention periods.
Very little solids accumulation was evident in Stage 2 of the anaerobic
AquaCell, with less than 0.02cu. meter after ten months.

Advanced Treatment

The final two cells of the Cardiff facility (Cells 4 and 5 -
Figure 2) are designed to achieve various levels of advanced tertiary
treatment. Both cells contain floating water hyacinths and duckweeds
for removal and recapture of nutrients for recycling purposes, and for
shading out of suspended algae. Several forms of BioWeb substrate are
used to greatly increase bacterial activity, particularly with regard
to nitrogen removal. BOD, suspended solids and nitrogen levels de-
cline in direct relation to the retention time of the water. With
water hyacinths as the major plant component, BOD and suspended solids
levels below 5 ppm can be achieved within 5 days retention time. Use
of duckweeds in place of hyacinths resulted in slightly decreased
treatment efficiencies, indicating an additional 20 to 30% increase in
retention time might be required to achieve the same treatment objec-
tive.
The percentage of total nitrogen removed by the aquatic plants is
relatively small in comparison to that by other elements of the AquaCell
system. Results indicate that a year-round average total of 182 grams
of nitrogen was removed per day by Cells 4 and 5. Yet, of this total,
only 18 g/day of nitrogen (10%) could be attributed to the biomass of
the aquatic plants, with 90% being removed by the BioWeb food chain
organisms and benthic denitrification processes (see also ref. 18).
Phosphate removal rates have been relatively low, ranging from 1
to 2 ppm during the 4.5 day retention period. This is as expected
since the phosphorous demand of aquatic plants, bacteria and inverte-
brates is only one-fourteenth to one-twentieth that of nitrogen.

394

Table 2

Coliform Removal By Primary, Secondary
and Tertiary AquaCells

MPN/100 ml %l
Removal
Treatment Stage (Effluent) Mean Values (Cumulative)

Raw Wastewater 50,200,000

Primary (Anaerobic) AquaCell 1,946,667 96.1%

Secondary (Facultative) AquaCell 623,000 98.6 %

Tertiary (Aerobic) AquaCells 17,666 99.96%

Sand Filter 5,633 99.99%

395

For situations where higher phosphorus removal is required, other
methods such as land application or chemical precipitation can be
integrated with the AquaCell system (11).
Reduction of total coliforms occurred rapidly (Table 2), with an
average 96% reduction occurring in the anaerobic AquaCell alone.
Initial data on viruses indicates removal rates as high as 100%. Re-
sults of these studies and studies now being completed on heavy metal
and chlorinated hydrocarbon removal rates will be published in a later
paper. Further information on results from the Cardiff AquaCell facility
can be obtained from references 11 and 20.

SOLAR AQUACELL SYSTEM DESCRIPTION AND DESIGN RATIONAL

The Solar AquaCell system is made up of a series of aquaculture
derived unit processes modified for greater process control and for
advanced treatment capability. The specific combination of AquaCell
types to achieve an overall treatment process is adaptable to site-
specific requirements, effluent quality requirements, and water or
by-product reuse desires. All AquaCells are based on modified lagoon
construction techniques as described in the preceeding section, and
incorporate high surface area BioWeb substrates of various configurations
to optimize conditions for the biotic components of the system and
reduce land area requirements. The following sections will discuss
further the design rational and physical characteristics of the unit
AquaCell systems, their application to various climatic and effluent
requirements and engineering criteria necessary for preliminary evalua-
tion.

Anaerobic AquaCell System (Primary Treatment)

The Anaerobic AquaCell (ANA) was recently developed by Solar Aqua-
Systems specifically for low operation and energy costs while still
achieving reliable primary or secondary treatment of wastewater. Pre-
treatment of raw sewage using a relatively simple, low cost technique
is useful in aquaculture processes as a means of buffering shock loads
and reducing solids to the following lagoons. Anaerobic processes are
routinely used for the reduction and stabilization of sludge, to a
lesser extent for the treatment of high BOD, industrial, and agricultural
wastes, and in a lagoon configuration, for preliminary treatment of
domestic wastes. The potential advantages of anaerobic treatment are
many and include (24,25):
I. Low Energy Requirements
Anaerobic processes do not require aeration and thus have signifi-
cantly reduced energy requirements compared to aerobic processes.
2. Capability of Producing Energy
One of the end products of anaerobic fermentation is methane gas.
Under proper conditions this gas can be utilized for heating and/or
production of electricity. McCarty (26) has estimated that anaerobic
digestion of municipal sludge and solid wastes and agricultural wastes
could yield about 20% of the current natural gas consumption in the
United States.
3. Excellent Solids Reduction and Stabilization
The potential of anaerobic processes for solids reduction and

.396

stabilization is well recognized as evidenced by the common use of
this methodology for sludge management. In addition, anaerobic
digestion of sludge induces an alteration of the water binding charac-
teristics which permits rapid and economic sludge dewatering.
4. High Loading Rates and Low Microbial Growth
High loading rate capabilities of anaerobic processes and conse-
quent ability to handle shock loads make them ideal for preliminary
treatment of wastewaters. The low microbial growth rates eliminate
the need for supplemental nutrients with nutritionally unbalanced wastes.
Despite these potential advantages, anaerobic treatment processes,
as currently used, have been troublesome, which has tended to limit
wider application. Two main problems have existed with conventional
methods, odors and process instability.
In the case of open anaerobic lagoons, lack of capability for pro-
cess control, and the lack of covers to seal in odors has limited their
use. High rate anaerobic sludge digesters also emit odors when they
malfunction or leak gas. The problem is with the basic design.
High rate biological systems are inherently unstable and require
close operator attention and control in order to obtain and maintain
proper performance. This is primarily due to the slow growth rates,
fastidious anaerobic requirements and sensitivity to environmental
change of the methanogenic portion of the anaerobic microbial popula-
tion. In anaerobic processes, two principle populations of microor-
ganisms are recognized, the acidic and the methanogenic bacteria. The
acidic bacteria are responsible for initial breakdown of the raw influent
organics into smaller molecules, mainly volatile acids. These acidic
bacteria are hardier and more resistant to environmental fluctuations
and influent toxins than the methanogenic bacteria. In addition, since
they have growth rates approximately 20 times that of the methanogenic
forms, the acidic bacteria are also capable of more rapid recovery after
upset and/or increased activity in response to variable influent loading
rates. The methanogenic bacteria convert the breakdown products of the
acidophiles into CO2 and methane gas. They are the more vulnerable of
the two populations to influent fluctuations and the slowest to recover
from upset. Conventional anaerobic systems are generally designed as
mixed processes in which these two populations of bacteria are cultured
simultaneously in the same volume. This strategy attempts to maintain
the proper balance and ratio between the two, with emphasis primarily
on the metahnogenic bacteria. However, close monitoring and control
of pH, temperature, and loading rates are necessary to prevent upset
(usually defined as cessation of methane production) and emission of
odors.
The Solar AquaSystems Anaerobic AquaCell is a slow rate anaerobic
process designed to take advantage of the volume dilution and relatively
inexpensive construction and operation costs of lagoon processes. The
use of high surface area fixed films provides the important advantage of
maintaining a stable environment for the anaerobic microorganisms. The
ANA is designed for preliminary treatment of incoming raw wastewaters
in order to reduce the loading rates and load fluctuations on the facul-
tative and aerobic AquaCell lagoons, reduce energy requirements for
preliminary treatment and for the following aerated treatment stages,
provide long-term digestion and storage of accumulating sludge, and re-
duce overall operator attention and maintenance requirements for the

397

entire wastewater treatment system. It is designed as a two-cell
system to separate the acidic and methanogenic microbial po1ati n�
and optimize conditions for each of these phases pif gl4p8big treatment.
t a aa!1gQuus iq concept to the dual cell systems of Coulter, et. al.
(21), Pretorious o3), pohlan and ~hosh (27), and Massey and Pohlgr4
(28).
The first cell of the anaerobic AquaCall is aT upfloYw ~1dge pon=
tact chamber similar to those designed and tested by Black (29),
Stander, et. al. (30), Simpson (22) and Lattinga (31) �d sameties
referred to as the anaerobic activated s u$d, pr-e,. ( es . Thits
cell contains primarily the hardy acidic bacteria which use the sludge
as a attce~ sttre. Hydr aulic retention times e alcuated to
permit this portion of the microbial population sufficient time to
perform initial breakdown of the incoming waste organics. In addition,
this first stage acts as a sedimentation basin and the sludge layer acts
as a physical filter for suspended solids, grease, and heavy metal
entrapment. Due to the mixing and heat (in winter) provided by the
incoming wastewater, sludge stabilization and reduction rates are
extremely high, while at the same time the use of low cost lagoon
construction allows sufficient volume to obtain long solids retention
times.
Reaction with sulfides in the sludge layer encourages the formation
of insoluable and non-toxic metal-sulfide complexes, thus de-toxifying
and removing a high proportion of incoming heavy metals from the efflu-
ent of the cell (33-34). This process is significant in that: 1)
removal of the heavy metals increases the safety for water reuse options
such as irrigation, groundwater recharge, etc., and 2) the methanogenic
pqcppri4 in cell 2 are protected from heavy metal toxicity, improving
process stability.
The operation of the 2nd cell of the anaerobic AquaCell is similar
in principle to the anaerobic filters of Young and McCarty (35), McKim,
et. al. (36), and Genung, et. al. (37). However, unlike the above
authors single cell digesters, the 2nd cell of the SAS Anaerobic 4qpuaaell
is a horizontal flow reactor designed primarily to culture methanogenic
bacteria. It is the main site of BOD reduction and methane production.
The methanogenic bacteria are provided with a high surface area of
fixed biofiln in the form of vertically oriented BioWeb substrates. In
addition to providing a stable attachment site for minimizing washout
of the methanogenic bacteria, the BioWeb substrates also accelerate
suspended solids removal from the process stream. The vertical orienta-
tion of the webbing allows "self-cleaning" and deposition of the coagu-
lated suspended solids to the cell bottom where solids red ctipn qnd
stabilization occurs. Because of the vertical orientation and the high void
volume of the BioWeb substrates, the system cannot be subject to blockage
as is the case with vertical flow packed-bed reactors. In addition, the
use of lagoon construction techniques with horizontal flow in this cell
permits retention volume increases economically to compensate for reduced
winter operating temperatures, exceptionally high loading rates, or
variable nutrient inputs. Retention times for the anaerobic Aqua6e4l
can vary between 12 hours to 4 days or more, depending on effluent
desired. Our experience with the anaerobic process and results from the
literature (37), indicate that use of extended retention times (i.e.
3-4 days) could achieve secondary quality effluent, although this has not

398

yet been tested. The anaerobic cell currently at the SAS Cardiff labora-
tory has a total retention time of only 14 hours.
Control of odors from the Anaerobic AquaCell is athie4eA by Use
bf a floating hypalon cover, tightly sealed along the edges of tht
lagoon. No odor problems have been encountered during the ten months
peratiehn df the anaerobic AquaCell.
Methahe production has not consistently been monitored at the
Cardiff facility. Howeverj based on kinetic rates of methane production
versus COD removal, reliable estimates can be provided for cost analysis
for use in heating and/or electrical pr-dudtlft. FSr 6kdtiP1 ad�uitfin
an average influent COD of 500 mg/L, a 70% teduetidn if dO0b by the AthAer
obic AquaCell and 65% CH4 composition of the released gas, Methane pro-
duction will average approximately 84.5 m3/day at a 3785 ml/day (1 tigd)
flow rate.
A criticism of anaerobic systems is the necessity of maintaining
elevated temperatures for maximum process efficiency. However, this
criticism stems mainly from experience with high rate anaerobic sludge
digestion systems which function in the mesophilic range of 30� to 37�C.
As Loehr (24) points out, "It does not follow that anaerobic treatment
must occur at optimum mesophilic temperatures. Satisfactory anaerobic
treatment can occur if an adequate mass of active microorganisms and a
sufficiently long solids retention time are provided for the system".
Furthermore, studies by Pfeffer (38) show that the relative drop in
Metabolic rate is less for anaerobic systems than for aerobic systems.
Additional information on the effect of tedtuced te1peratures on anaer-
obic wastewater treatment processes comes frtO successful experience for
many years with anaerobic lagoons in Alaska (39) and in Canada (40).
In addition, Genung, et. al. (37), working with an anaerobic fixed film
bioreactor similar in operational principle to Stage 2 of the SAS
Anaerobic AquaCell, states that tepetatte dhaigeb in the range of
10� to 25� C did not significantly effett removal rates. Coulter et.al.
(21) found only a 15% reduction in BOD temoval between winter (4�C)
and summer (220C) conditions in their pilot investigations of an anaer-
obic contact process. The SAS Anaerobic AquaCell has been operated with
influent temperatures ranging from 180C to 31�C with no apparent change
in removal efficiency. For cold climate locations, an increase in reten-
tion time fron 0.5 up to 1-2 days should prove adequate to maintain
"advanced" primary treatment. Snow, ice or ice loads on the floating
cover ptresent no problem, and in fact add to insulation to reduce heat
loss.
Sludge handling with conventional primary sedimentation and secondary
treatffent processes is a critical and costly problem (41), since there
is little in situ solids reduction and/or stabilization in most of these
systems. In addition to increased capital, energy and maintenance costs,
conventional digestion systems require close operator attention and con-
trol for proper functioning, and thus are not cost effectivefor
aquaculture systems.
The design of the SAS Anaerobic AquaCell provides simplified and
superior solids reduction due to long, in situ, sludge retention times
which eliminate daily handling problems and reduce final volumes.
Representative daily dry solids accumulation rates for six conventional
wastewater treatment processes (42) and the SAS Anaerobic AquaCell are
given in Table 3. An 85% reduction rate for a six month sludge retention

399

TABLE 3

COMPARISON OF SOLIDS PRODUCTION BY THE ANAEROBIC AQUACELL WITH CONVENTIONAL METHODS

PROCESS TYPE TREATMENT LEVEL SEPARATE FREQUENCY DRY SOLIDS
NUMBER OF PROCESS RE- OF PER DAY
PROCESS Primary Secondary QUIREDFOR SOLIDS @ FLOW KATE OF
SLUDGE REMOVAL 3785 m /DAY
DIGESTION? (1 MGD),OR(4)
10,000 PEOPLE'

I SAS Anaerobic AquaCell Yes (5) No Once per 6-12 Months 170 kg (375 lb)
2 Septic Tank(2) Yes No :No Once per 1-2 Years 367.4 kg (810 lb)

3 Imhoff Tank(2) Yes No No Once per20-60 Days 313 kg (690 lb)

4 Primary Sedimentatioj2) Yes No Yes Daily 340.2 kg (750 lb)

5 Primary Sedimentation Yes Yes Yes Daily 558 kg (1230 lb)
& Trickling Filter
With Secondary Sedi-
mentation (2)

6 Primary Sedimentation Yes Yes Yes Daily 635 kg(1400 lb)
& Activated Sludge 2)

7 Activated.Slud e(2'3) Yes Yes No Daily 1020.6 k
(Package Plant) (2250 lb)

(1) Assuming water usage of 378.5:1/person/day (100 gpd) and 300 mg/l or 0.25 lbs/person/day of S.S.
in wastewater.
(2) Data from: Water Pollution Control Federation. 1977. MOP/8 - Wastewater Treatment Plant:Design
Washington, D.C. 560 pp.
(3) Raw wastewater discharged directly to aeration tanks.
(4) To determine dry solids production for other treatment capacities, multiply or divide by proportional
factor based either on flow rate or number of people served.
(5) Our results to date indicate that longer retention times in the anaerobic AquaCell should produce
secondary effluent levels. We are now beginning tests to determine this.

time was used to calculate dry solids production for the SAS Anaerobic
AquaCell, which, according to our data, is somewhat conservative. As
can be seen from Table 6, there is 50% less sludge to handle with the
AquaCell system as compared to conventional primary sedimentation
(primary treatment with separate sludge digestion facilities) 69% less
than a trickling filter plant (secondary treatment) and 73% less than
an activated sludge plant (secondary treatment). At influent suspended
solids concentrations averaging 300mg/L sludge pumping & disposal will be
required only once per year from the anaerobic AquaCell. In aquaculture
treatment systems using macrophyte plants such as water hyacinths, the
digested sludge can be mixed with harvested plants to make a more at-
tractive compost.

Facultative AquaCell (Secondary and Advanced Secondary Advanced Treatment)

Facultative lagoons are in world-wide use for wastewater
stabilization due to their relative simplicity and ability to handle
wide variations in organic loading. The SAS Facultative AquaCell
operates at a higher rate than conventional facultative lagoons in
order to reduce land area requirements anywhere from one tenth to
one fiftieth of conventional lagoons. This size reductionand higher
loading rate capability are made possible by the high surface area
BioWeb substrates and efficient diffused aeration systemwhich also
contribute to increase process stability. The facultative AquaCell
design maintains anaerobic conditions in the lower portions of the cell
to reduce energy requirements and provide for anaerobic digestion and
stabilization of precipitated suspended solids.
Retention times of the Facultative AquaCell can vary between 0.5
to 1.5 days, depending on effluent quality requirements and local
climactic conditions. It is normally recommended that an anaerobic
AquaCell be placed in series before the facultative AquaCell to reduce
and stabilize organic loading and consequent aeration requirements.
In this two-stage configuration, a total retention time of only
2-3 days are required to reliably achieve advanced secondary quality
effluent (BOD, T.S.S. less than 10 mg/L). One to two days are required
to achieve standard secondary quality effluent levels (BOD, T.S.S.
less than 30 mg/L). Complete nitrification, if required, can also
be accomplished in the facultative AquaCell with an increase in applied
aeration and/or retention time.
The Facultative AquaCell, as described above, does not require
aquatic plants to achieve a secondary or advanced secondary treatment
level. Increased suspended solids from growth of planktonic algae
have not been a problem with the SAS Facultative AquaCell due to the
relatively short retention periods (0.5 - 1.5 days). In addition,
no greenhouse cover is required, even in areas with severe winters,
provided retention time is sufficient to compensate for reduced meta-
bolic rates at reduced temperatures. In cases where removal and reuse
of nutrients is desired, floating aquatic plants can be grown and
harvested from the facultative AquaCell. In tropical areas, hyacinths
and/or duckweeds can be grown year-round without greenhouse covers. In
the United States, a greenhouse covering would be required for most
areas if hyacinths are to be used on a year-round basis. Alternatively
hyacinths can be grown during warm periods and duckweeds during the

401

winter, since certain species of duckweeds are very cold tolerant.
In areas with severe winters, the use of a greenhouse cover will improve
winter performance, permit a decrease in required retention times, and
allow growth of aquatic plants on a year-round basis. These design
options must be considered on a case by case basis.
With primary treatment, sludge buildup in the facultative AquaCell
has averaged approximately 8 to 10 mm per year. Thus, there should be
no requirement for sludge removal from the cell for fifty to sixty.
years of operation. There is also no need for a final clarifer and/or
recirculation requirements.

Aerobic AquaCells- Advanced (Tertiary) Treatment

Advanced or tertiary wastewater treatment using the Solar AquaCell
System is achieved by passing the secondarily treated effluent of the
anaerobic- facultative AquaCells through an additional aerobic AquaCell
or Cells. The aerobic AquaCell contains floating aquatic macrophytes
(water hyacinths and/or duckweeds) to further reduce BOD, suspended
solids, and nitrogen to meet advanced treatment effluent levels.
Treatment rate in the aerobic AquaCell is a linear function of
retention time and temperature. As previously stated, the biological
film of microorganisms on the BioWeb substrates are responsible for the
major portion of treatment, with the aquatic plant components account-
ing for only 10-20% of the total nutrient removal (11,18). Packing
densities for the BioWeb can vary from 46,500 m3 (500,000 ft2) to
186,000 m3 (2,000,000 ft2) of active surface area per 0.4 ha (1 acre)
(equivalent to 0.19 m2 (2 ft2) to 0.56 m2 (6 ft2) per 3.785 L (1 gal)
per day , depending on treatment objectives and cost benefit analysis.
Since this represents two to six times greater active surface area than
conventional bio-film processes (trickling filter or bio-disc), it
allows use of conservative design practices and increases the shock
loading capacity of the AquaCell system.
The use of a greenhouse for covering the tertiary cells is dependent
on local climatic conditions and the type of macrophyte plant cover
selected. In tropical areas, no greenhouse cover is required for heat
retention or to allow growth of hyacinths and duckweeds on a year-round
basis. In areas with an abundance of water fowl, e.g. near migratory
routes or winter feeding grounds, the duckweed will have to be protected
with a light, low cost bird netting over the ponds. In areas with arid
climates and consequent high evaporation rates, increases in total dis-
solved solids could become a problem and require use of a single layer
tensile greenhouse covering. In cooler zones, the use of a greenhouse
cover is dependent on the type of aquatic plant cover used. Duckweed,
being more cold tolerant than hyacinths, can be cultured on a year-
round basis in the southern and southwestern portions of the U.S. without
greenhouse cover. However, hyacinths will require a greenhouse cover
almost anywhere in the U.S. if reliable winter treatment objectives are
to be met. An option, as described for the facultative AquaCell, is to
utilize hyacinths during spring, summer and fall and duckweeds during
the winter periods, though use of duckweeds year-round allows simpler
harvesting procedures and equipment. In northern areas of the U.S. 'i.e.
generally above 38"N subject to regional differences especially in the
central and eastern states), a greenhouse cover is a requirement for

402

year-round tertiary treatment operation with any species of plants.
As previously mentioned, phosphorus removal in the AquaCell system
is relatively slow, estimated at 0.5 - 1 ppm per day retention time.
Where complete phosphorus removal is required, either an increase in
retention time or lime precipitation can be utilized. With lime precipi-
tation, only about 30% of normal liming quantities is required due to
the tertiary AquaCell removal of interferring organic substances (BOD,
S.S., and ammonia) from the effluent.
Duckweeds are harvested from the AquaCell system by means of a
continuous in line effluent skimming device adjustable to draw off either
surface or subsurface effluent. Separation of duckweeds from the efflu-
ent works effectively by use of static screening, after which the duck-
weed can be conveyed or pumped as a slurry to the reuse area. Duckweeds
make an excellent food supplement for fish, chickens, pigs, or cattle,
due to their high protein content. Alternatively, they can be composted
with sludge removed from Stage I of the Anaerobic AquaCell for soil
application, or digested for methane production. Hyacinths can be re-
moved periodically from the aerobic AquaCell by means of an in-pond
pusher boat and a bank mounted chopper/conveyor. The hyacinth slurry
is then pumped to the reuse area. A unit developed by Solar AquaSystems
requires use of only one man for operation. The hyacinths can be com-
posted to produce a high quality soil amendment, which, in addition to
increasing nutrient content of the soil also increases moisture retention,
due to its fiberous nature. Alternatively, the chopped hyacinths can
be used for methane production or as an animal food supplement.
Retention times for an Anaerobic-Facultative-Aerobic AquaCell system
designed to provide advanced tertiary treatment will vary with climate
and effluent options. For example, to achieve an advanced tertiary
treatment effluent suitable for many industrial or recreational needs,
approximately 5-6 days total retention are required. To produce water
of drinking water quality, retention times of 8-12 days are required to
ensure complete safety. In colder climates, retention times will in-
crease dependent on ambient operating temperatures experienced at the
particular site. Use of the double layer tensile structure greenhouse
allows year-round operation with reduced retention times in these
situations.

Land Area Requirements

For primary treatment, in regions where water supplies are not a
problem, and which lie next to deep oceanic areas suitable for discharge
of primary treated wastewater, advanced primary treated effluent with
ocean discharge may be the most cost effective treatment alternative.
In these cases, use of the Anaerobic AquaCell can provide an advanced
primary treated effluent with minimum operation and maintenance costs.
Land requirements would be 0.1 ha (0.25 acres) to 0.2 ha (0.5 acres) of
water surface area per 3785 m3/day (1 mgd) for this level of treatment,
depending on climatic zone and treatment level desired. There are no
land requirements for separate sludge digestion facilities or processes
associated with sludge digestors. Since solids reduction in the Anaero-
bic AquaCell is approximately 50% greater than for conventional primary
treatment facilities (table 3), land area requirements for drying beds
are also reduced.

403

Secondary treatment by means of the Anaerobic-Facultative AquaCell
combination would require 0.4 ha (1 acre) to 0.7 ha (1.5 acres) of
lagoon surface per 3785 m3/day (1 mgd) depending on climatic conditions
and effluent qualities (secondary or advanced secondary) required. Since
there is no requirement for separate sludge digestion facilities, final
clarifiers and a 69 to 73% reduction in sludge drying bed requirements
as compared to conventional activated sludge and trickling filter
processes (Table 3), the total land area requirements for an AquaCell
secondary or advanced secondary effluent process are actually smaller
than that required for conventional processes. In addition to reduced
land area requirements, the AquaCell process provides a greater biologi-
cally active surface area for treatment, higher dilution factors, a
simplified process train and significantly lower energy requirements
than conventional alternatives.
For advanced treatment, a Solar AquaCell system consisting of the
Anaerobic-Facultative-Aerobic AquaCells in series will require 1.6 ha
(4 acres) to 2.4 ha (6 acres) of lagoon surface per 3785 m3/day (1 mgd)
depending on effluent quality requirements and local climate. Additional
land for composting of harvested macrophytes, sludge drying and control
building represents the only other land area requirements.

Energy Requirements

Operation of the Anaerobic AquaCell for primary treatment of waste-
waters can be viewed as an energy producing process if the methane gas
produced by the process is utilized, either for heating purposes or to
drive an electrical generator. The process itself requires no energy
input. The only other energy costs (aside from influent and effluent
pumping if required) are for comminutation, intermittant sludge pumping
and disinfection.
For secondary treatment levels (Anaerobic-Facultative AquaCell),
energy requirements for aeration of the facultative AquaCell would vary
from 6 kW/h to 7.5 kW/h per 3785 m3/day (1 mgd) for secondary to advanced
secondary treatment, with an increase to 15 kW/h per 3785 m3/day (1 mgd)
for complete nitrification. Comminutation, intermittant sludge pumping
from the first stage of the anaerobic AquaCell and disinfection represent
the only other energy requirements of the system. If the methane gas from
the anaerobic AquaCell is utilized, a large proportion of the energy
requirements could be met from this source.
Energy requirements for advanced (tertiary) treatment (Anaerobic-
Facultative-Aerobic AquaCells) range from 18.6 kW/h to 22.4 kW/h per
3785 m3/day ( 1 mgd). Other process energy requirements which include
harvesting of the aquatic plants, solar heat transfer spraying, inter-
mittant sludge removal from the first stage anaerobic AquaCell and dis-
infection are all minor when compared to the continuous energy require-
ments for aeration. Again, a proportion of this total energy require-
ment could be met by utilization of methane gas produced by the naaerobic
AquaCell.

Other Operation and Maintenance Costs

Operation and maintenance of the AquaCell process is exremely low
compared to conventional processes. These savings are a result of the

404

following characteristics of the AquaCell system:
1. In situ sludge digestion - There are no requirements for
external sludge digestion facilities or chemical costs. Intermittant
sludge pumping direct to the drying beds or liquid tank transport are
the only 0 & M requirements for sludge management.
2. No recirculation process, clarifiers, or other process units
required. The main mechanical components of the AquaCell system are the
blowers, comminutor, disinfection and harvesting equipment, if aquatic
macrophytes are used, all of which are low maintenance items. There
are also few process pipes subject to potential clogging and/or breaking.
3. Reduced disinfection costs - Due to the high removal rate of
coliforms, disinfection requirements are significantly reduced, saving
on both capital costs, costs of chemicals and operator attention
requirements.
Operator skill and attention requirements for the primary and
secondary treatment processes (Anaerobic and Facultative AquaCells) are
minimal. The process can go for long periods with only periodic checks.
Approximately 0.5 operators per 3785 m3/day (1 mgd) is estimated for
secondary treatment. The main operator requirements for tertiary treatment
are harvesting and composting, which are performed on a weekly to monthly
basis depending on the season. Operator requirements for tertiary treat-
ment is approximately 1-1.5 operators per 3785 m3/day (1 mgd). Because
of the relative simplicity of the process, operator training requirements
are also minimal.

Capital Costs

Capital costs for a complete secondary treatment AquaCell process
(Anaerobic and Facultative AquaCells) should range between $1.00 to 2.00
per 3.785 L (1 gal) of treatment capacity, depending on local codes,
labor and equipment costs, use of a greenhouse cover and effluent quality
requirements. Capital costs of an advanced (tertiary) treatment AquaCell
facility (Anaerobic-Facultative-Aerobic AquaCells) should range between
$2.50 to $4.00 per 3.8 L (1 gal) of treatment capacity, depending on
effluent quality desired, location and size of the process, labor costs,
etc. Since the AquaCell system is an innovative treatment process,
it qualifies for 85% federal assistance. Because of the low 0 & M of
the AquaCell process overall life cylce costs will be substantially below
conventional processes. A community can easily recover the 15% share
of capital costs on savings in operation and maintenance costs as com-
pared to conventional processes.

SOLAR AQUACELL AWT SYSTEM FOR THE CITY OF HERCULES

The City of Hercules is a small but rapidly growing planned commun-
ity 48 km (30 miles) northeast of San Francisco which is presently com-
pleting construction of an innovative Solar AquaCell wastewater treatment
system. Startup of the first phase, designed to treat 1,325 m3/day
(350,000 gpd) of raw wastewater to advanced tertiary quality is scheduled
for late January, 1980. The final phase will treat 7,570 m /day (2 mgd)
to advanced tertiary quality. This system can produce a range of
effluent quality for multiple reuse options, as well as recycling 100%

405

of the harvested aquatic plants, solids and digested sludge into reusable
by-products within the community. A detailed discription of this facility
has been previously published (44), so only a summary is presented below,

Facility Design

The Hercules facility is designed as a three-phase system cotiating
of an anaerobic AquaCell, followed by a facultative AquaCell and a latgef,
third phase aerobic AquaCell containing water hyacinths and duckweeds
(Figure 6). In the ultimate facility (7570 m3/d or 2 mgd), three inde-
pendent facultative/aerobic AquaCell units will be operated in parallel
to permit the City flexibility to select andmore efficiently meet 9hdiA=
ing water discharge or reuse needs. For the first phase, scheduld f6t
startup in January, 1980, only about one-half of Solar AquaCell iA" i�
being constructed.
Pretreatment will consist only of grinding (commifiutatr) The tb
stage anaerobic AquaCells are designed to provide 21920 hetc total re-
tention time. The second AquaCell (facultative) and the third AquaCell
(aerobic with aquatic plants) in each series are combined in the same
earthen pond, with a rubber curtain wall hydraulically separating and
providing a channel for the facultative treatment area. The facultative
cell will not contain water hyacinths or duckweeds in order to maximize
oxygen exchange through the surface.
In the aerobic (tertiary) AquaCell stage, oxygen levels will range
from 2 ppm at the influent to 6 ppm or greater at the effluent end.
Water hyacinths and duckweeds will be cultured over the entire water
surface of this stage in order to prevent growth of algae, to assist
the BioWeb reduction of BOD, SS, total dissolved nitrogen and phosphates,
and to produce a valuable by-product. Multiple overflow screens will
reduce escape of detritivore invertebrates, fish or plants.
The only posttreatment process required for secondary quality efflu-
ent will be disinfection. Ozone was selected over chlorine, in spite of
its slightly increased costs, for several reasons. Dechlorination would
be necessary for bay discharge, thus increasing total costs of chlorine
usage. For reuse needs, chlorine is less desirable since it is known
to increase levels of potentially toxic chlorinated hydrocarbons, and
does not provide the additional oxidation and back-up treatment capability
of ozone. For tertiary effluent needs, sand filtration before ozone
treatment will assure removal of any remaining suspended solids.

Advantages of the Solar AquaCell System to the Community

With the ultimate 7570 m3/d (2 mgd) facility, the three separate
Solar AquaCell lagoons (Figure 6) will be operated in parallel to allow
the City flexibility to select for and more efficiently meet changing
water reuse and/or discharge criteria. By varying the wastewater flow
to each of the three AquaCells, retention times can be proportionally
increased to produce a secondary quality effluent for irrigation or bay
discharge. For example, if a market exists for 3785 m3/d (1 mga) of
high quality water (e.g. BOD, TSS less than 3.0 ppm; total nitrogen less
than 5.0 ppm; ammonia less than 0.1 ppm), than 50% of the 7570 --,;d ;2
mgd) flow can be diverted through 2 of the 3 lagoons at an average
retention of 10 days, while the remaining 3785 m3/d (1 mgd) is reated

406

PROPFIE.D 2,.0 MGD SOLAR :AOUEilJLL FACILIiT - LITYI F HERCULES

li 1 FA-tUTAiVTIE ZELL - -MIAMUTATIVE CELL

- -j 1 t

L ~ SOLAR iQUAQELL C : D.LMR ,AIUACELL B _
| ~~(AER1BTC, 2 ACRES) f (ERGIBJC., 2 - ACRES)

AINI1ROB9.'C POND ANAEROBIC POND I | 1
(floating cover) (f3oating cover)

SOLAR AQtUACELL A
h=P<~~~ ;X > _(AEROBIC: 2 ACRES)

sand fil'erq -- '- I t

- -- --FACULTAT'V Cll _
| I |sand filt IVE CELL
r r
aquatic plant ( ozone , pump
Irecycling area II station, & oper- I
(compost & Bio-gas)| I ations bldg. I Current Phase I lagoon under
areasI -_ _J - g~ area construction.

_ nfluent 1 _--
effluent

Plan View of the proposed 2.0 MGD Solar AquaCell Lagoon Treatment Facility for the City of Hercules,
California. Each AquaCell will be 2.0 acres (6 acres total). The 0.35 MGD treatment phase currently
under construction consists of a 1.5 acre AquaCell system with anaerobic, facultative and aerobic stages,
approximately � of AquaCell A.

to secondary quality in the third lagoon with a retention time of two
to three days.
Cost analysis indicated that a 7570 m3/d (2 mgd) AquaCell system
designed to produce an advancedtertiary quality water could be con-
structed for about the same cost (3.5 million - 1977 dollars) as a
7570 m3/d (2 mgd) expansion of the existing activated sludge facility
at neighboring Pinole. In addition to producing only secondary quality
effluent with limited reuse options and value, the Pinole alternative
would have required much greater pumping distances. The high construc-
tion, maintenance and operation costs of conventional, high technology
AWT facilities, compared to the Solar AquaCell process ruled the former
out of consideration by the City.
The low energy requirements of the Solar AquaCell process, and
greatly reduced maintenance, sludge handling and labor expenses should
reduce annual 0 & M costs to about 50% less than projected 20 year costs
for the alternative activated sludge system, even though a much higher
quality water will be produced. This cost savings differential is
expected to increase as energy costs continue to escalate. Personnel
needs will be limited primarily to harvesting and composting activities,
requiring only one to two full-time operators per 7570 m3/d (2 mgd).
The aquatic plants harvested on a regular basis can be reused by
conversion to either methane gas, high quality organic compost, or sold
as an animal feed supplement. Hercules preferred reuse of the plants
in the form of compost, needed in large quantities for landscaping
purposes during development of their community over the next 20 years.
An additional advantage with composting is derived by composting the
digested sludge removed periodically from the first stage anaerobic
AquaCell with the harvested plants. By composting both forms of waste-
water solids together for recycling, the sludge takes on a more attrac-
tive marketing form and in-turn further enriches the nutrient value of
the plant compost. In this manner, 100% of all solids can be recycled
directly within a community instead of paying for hauling to out-of-town
dump sites, as is currently done with most neighboring conventional
treatment plants. Total solids handling volumes will also be reduced
compared to alternative treatment methods. Further, the relative simpli-
city and stability of the composting and anaerobic AquaCell digestion
processes, in comparison to conventional primary treatment and high rate
anaerobic digestion methods, greatly reduces operator skill requirements,
odors and process failures common with conventional solids handling
methods.
The Solar AquaCell Treatment Facility has been designed by Solar
AquaSystems, Inc., Encinitas, California. KCA Engineers, Inc., San
Francisco, provided engineering on basic treatment facility components.
The City of Hercules was recently honored with the State of California's
Governor's award for the most appropriate technology project of the year.
The AquaCell system is a proprietary and patented system of Solar
AquaSystems, Inc. Further information on che process can be obtained
by writing Solar AquaSystems, Inc., P.O. 3ox 88, Encinitas, CA. 92024
or calling (7t4) 753-0649.

408

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12. Bunch, R.L. 1979. Introduction and Objectives of Symposium.
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409

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20. Stewart, W.C., C.R. Alsten, S.A. Serfling and D. Mendola. 1979.
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21. Coulter, J.B., S. Soneda, and M.B. Ettinger. 1957. Anaerobic
Contact Process for Sewage Disposal. Sewage and Industrial
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22. Simpson, D.E. 1971. Investigations on a Pilot-Plant Contact
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23. Pretorius, W.A. 1971. Anaerobic Digestion of Raw Sewage. Water
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24. Loehr, R.C. 1971. Anaerobic Treatments of Wastes. In Develop-
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25. McCarty, P.L. 1964. Anaerobic Waste Treatment Fundamentals.
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26. McCarty, P.L. 1973. Methane Fermentation - Future Promise or
Relic fo the Past? Proc. Bioconversion Energy Research Conference,
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410

27. Pohland, F.G. and S. Ghosh. 1971. Developments in Anaerobic
Stabilization of Organic Wastes - Two-Phase Concept. Environ.
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28. Massey, M.L. and F.G. Pohland. 1978. Phase Separation of
Anaerobic Stabilization by Kinetic Controls. Journal W.P.C.F.
50:2204-2222.

29. Black, M.G. 1974. Operational Experiences with an Abattoir
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30. Stander, G.J., G.C. Cillie, W.R. Ross and R.D. Baillie. 1967.
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31. Lettinga, G. 1979. Direct Anaerobic Treatment Handles Wastes
Effectively. Industrial Wastes. 25:18-41.

32. Kirsch, E.J. and R.M. Sykes. 1971. Progress in Industrial
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33. DeWalle, F.B., E.S.K. Chian and J. Brush. 1979. Heavy Metal
Removal with a Completely Mixed Anaerobic Filter. Journal W.P.C.F.
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34. Gould, M.S. and E.J. Genetelli. 1975. Heavy Metal Distribution
in Anaerobically Digested Sludges. Proceedings of the 30th
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35. Young, J.C. and P.L. McCarty. 1967. Anaerobic Filter for Waste
Treatment. Eng. Bull. Purdue University Eng. Ext. Ser. 129:559-
574.

36. McKim, M.P., A.A. Cocci, T. Virarghavan and R.C. Landine. 1979.
Combined Aerobic-Anaerobic Treatment Produces Low Cost, Quality
Effluent. Industrial Wastes. 25:53-55.

37. Genung, R.K., D.L. Million, C.W. Harcher and W.W. Pitt, Jr. 1978.
Pilot Plant Demonstration of an Anaerobic Fixed-Film Bioreactor
for Wastewater Treatment. Paper presented at the Symposium on
Biotechnology in Energy Production and Conservation, Gattinburg,
Tenn. May 10-12, 1978.

38. Pfeffer, J.T. 1970. Anaerobic Lagoons - Theoretical Considera-
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Treatment Lagoons, Kansas City, Missouri. June 23-25, 1970.

39. Clark, S.E., H.J. Coutts and R. Jackson. 1970. Alaska Sewage
Lagoons. pp 221-231. In 2nd International Symposium for Waste
Treatment Lagoons, Kansas City, Missouri. June 23-25, 1970.

411

40. Dornbush, J.N., 1970. State-of-the-Art - Anaerobic Lagoons,
pp. 382-387. In 2nd International Symposium for Waste Treatment
Lagoons, Kansas City, Missouri. June 23-25, 1970.

41. Vesilind, P.A., 1979. Treatment and Disposal of Wastewater
Sludges. Ann Arbor Science. Ann Arbor, Mich., 323 pp.

42. Water Pollution Control Federation& American Society of Civil
Engineers, 1977. MOP/8 - Wastewater Treatment Plant Design.
Water Pollution Control Federation, Washington, D.C. & American
Society of Civil Engineers, N.Y. 560 pp.

43. 2nd International Symposium for Wastewater Treatment Lagoons., 1970
Kansas City, Missouri, 404 pp.

44. Serfling, S.A. & D. Mendola, 1979. The Solar AquaCell AWT Lagoon
System for the City of Hercules, California. pp 671-680. In Pro-
ceedings - Vol. 1, Water Reuse - From Research to Application.
A.W.W.A. Research Foundation, Denver, Colorado. 781 pp.

412

Economics, Energy, and By-Product
Utilization Session

Session IV

ECONOMICS, ENERGY, AND BY-PRODUCT UTILIZATION

John Colt and Maurice Bender

Rising energy costs will have a significant impact on the selection of

treatment processes in the 1980's. Conventional advanced wastewater treatment

systems and some forms of secondary treatment may become prohibitively

expensive. Treatment systems using aquatic plants and animals represent a

low-cost, low-energy alternate method of treating wastewater, and at the same

time allow for the recovery of energy and nutrients.

The energy consumption for wastewater treatment in the United States

(1979) is about 0.15 quads (or 0.15 x 10 15BTU/year). This represents about

0.2 percent of the nation's energy usage. By 1990, it is projected that this

energy usage will double to about 0.26 quads.

While these numbers are small relative to the national energy consumption,

they are significant on a local level. The energy consumption by municipal

treatment plants may represent 113 to 1/4 of the energy purchased by many

local governments.

Aquatic treatment systems are land-intensive, using 5 to 40 acres per

Mgal/d (million gallons/day). These systems use much less energy and resources

than conventional systems (such as activated sludge), and therefore, increases

in energy costs will have less impact on the economics of aquatic treatment

systems. Also, the salvage value of the land may represent a significant monetary

return.

The cost of a I Mgal/d water hyacinth system for advanced secondary

treatment (BOD and Suspended Solids < 10 mg/L) ranged from 35 to 57 percent

of conventional treatment. The use of aquatic systems with land treatment and

oxidation ponds are cost-effective for advanced wastewater treatment.

415

Aquatic treatment systems may also allow significant resource recovery.

Aquatic plants may be used for soil conditioners, paper, or cattle feed. Harvesting

and processing costs as well as the value of the final product are not well

defined at this time. Public health aspects of pathogen transmission or heavy

metal and trace organic concentration may restrict the use of these items for

animal or human consumption.

The most economic energy recovery system for small communities may

be low-temperature gasification (pyrolysis) rather than anaerobic digestion. The

seasonality of aquatic plant production may require special management

techniques, greenhouse cover, or additional storage during the summer. By year

2000, wastewater aquaculture may supply a net energy contribution of between

0.01 and 0.05 x 1015 BTU/year or 0.01 to 0.05 percent of our energy consumption.

Even though the economics of aquatic systems appear highly favorable,

implementation of this technology may be delayed by legal and political factors.

Legal problem areas may be the National Environmental Policy Act (environmental

impact statement), the Food and Drug Administration (if any of the products

are consumed by humans or animals), and water rights law, especially in the

western United States. Legal and political conflicts can be dealt with by the

establishment of a lead agency to coordinate planning, public information, and

legal requirements. Citizen participation at all stages may help address many

of the social and political problems. Public acceptance of innovative technology

may be greater than that of the regulatory agencies.

416

ENERGY CONSUMPTION, CONSERVATION AND RECOVERY
IN MUNICIPAL WASTEWATER TREATMENT - AN OVERVIEW*

Maurice F. Bender
Argonne National Laboratory
Argonne, Illinois 60439

Abstract

The potentials for energy consumption, conservation and recovery
at municipal wastewater treatment plants are relatively small compared
to the national energy figures. Nevertheless they are significant,
particularly to local owners and operators. Estimates of energy con-
sumption, as well as opportunities for conservation and energy recovery
in municipal wastewater treatment operations, are reviewed. The relation-
ship between energy conservation and aquaculture based wastewater treat-
ment systems is also introduced. Finally, current Department of Energy
activities in this area are presented.

When we speak of energy consumption in wastewater treatment in relation to
the natural energy consumption fig~ures, we speak of relatively small numbers.
Although there is considerable variability in the figures currently available,
a commonly accepted range of values is that municipal wastewater treatment
accounts for about 0.1 to 0.3 percent of the nation's energy usage. This
amounted to about 0.15 quads or 0.15 x 1015 Btu's in 1978. We also anticipate
that, except for unforseen major breakthroughs in energy conservation and
recovery technology by 1990, we can expect this energy usage to roughly double
to about 0.26 quads. Again, there is some difference of opinion on this
estimate. The doubling can be attributed to an increased volume of wastewater
and to the higher degree of treatment required to meet more stringent Federal
and state limitations. The relationship comes about because it becomes increas-
ingly difficult to remove wastewater constituents as the degree of treatment
required increases. Traditionally, the more sophisticated the removal process,
the more energy required to extract a given mass of pollutant from the waste
stream. Advanced treatment processes, for example, often require large quan-
tities of chemicals that require energy intensive methods of production.

Although the numbers are relatively small on a national usage scale, they
are significant, particularly on a local level. The cost of supplying energy
to a typical wastewater treatment plant generally represents between 20 and 40%
of the overall operating budget. In general, the energy consumption by munic-
ipal treatment plants represents an estimated one quarter to one-third of the

417

energy purchased by many local governments. Depending upon the scenarios
employed we are speaking of an increased cost of approximately one-half to
one billion dollars to municipal governments through the year 1990. Conse-
quently, there is or should be strong motivation for support, *at the local
level, to meet the goals for energy conservation in wastewater treatment.
Professionals will have to become increasingly better informed of energy
considerations in the planning, design, construction, operation and mainte-
nance of wastewater treatment plants. The Department of Energy and the
Environmental Protection Agency have embarked on such efforts and I will speak
further on this subject a bit later.

Energy considerations are closely related to a number of design factors
employed in the planning and designing of an overall wastewater treatment
process. The actual energy consumption by a given plant is a function of such
variables as the location of the plant, the treatment processes employed, the
age of the plant and the effluent limitations that have to be met. The cost
of the energy, calculated over the lifetime of the plant, must be coupled with
these considerations.

One of the greatest opportunities for energy conservation in wastewater
treatment plants lies with the energy currently consumed by prime movers such
as pumps and blowers. Based upon reviews of detailed energy audits of specific
plants, such as the energy audit for the West Southwest Plant of the Metro-
politan Sanitary District of Greater Chicago, it becomes apparent that 90% or
more of the energy consumed at most plants can be attributed to prime movers.
At the West Southwest Plant the total energy consumption in 1976 was about
2.5 billion kilowatt hours (kWh) of which 2.2 kWh were attributed to prime
movers. A notable fact is that due to the large amounts of energy consumed
in pumping air into an activated sludge system, this type of treatment is one
of the most energy-intensive processes employed in wastewater treatment.

The optimization of the pumping operations to reduce energy consumption,
therefore, should be a focal point for energy reduction. There are three
general areas for optimizing the energy efficiency in pumping operations. They
are: 1) the selection of the approproate pumps for a given job, 2) optimizing
overall system performance, and 3) the proper operation and maintenance of the
pumps. It should be noted that this major consumptive use of energy in most
plants is also inherently a problem in aquaculture wastewater systems, and
optimization of pumps selection, operation and maintenance should be considered
in these systems as well.

There are a number of opportunities for increased energy conservation and
recovery which I want to touch upon. (John Beneman, one of the speakers in our
session, will speak further on the subject of energy recovery.) These oppor-
tunities include the following:
�improved dewatering methods in the context of an optimum sludge
management strategy,

� increased utilization of sludge digestion gas,

� use of chemicals or other materials which require less energy in
their production than are currently employed,

418

o more energy efficient design of treatment plant buildings,

� the use of small turbine-generators at the outfalls from waste-
water treatment plants,

� combined sludge and solid waste energy recovery systems.

These are just a few of the areas where we can develop more energy efficient
and generally more cost effective systems while meeting water quality requirements.

I will now spend a few minutes discussing DOE's activities and plans in
this area. In particular, I will talk about the Urban Waste and Municipal
Systems Branch in the Office of Conservation. Don Walter is the Branch Chief.

DOE has recently completed a draft program plan for energy conservation
and recovery in wastewater treatment plants. Although I believe it will require
considerable reworking, it is extremely gratifying to some of us who have nur-
tured such an effort. The plan is directed towards stimulating the development
and commercialization of technologies to reduce the energy requirements and to
increase the efficiency of wastewater and water treatment processes. For the
near term, it places a strong emphasis upon retrofitting existing plants. The
emphasis is upon working closely with the EPA, and Department of the Interior,
and other agencies, in complimenting their objectives, as well as working towards
DOE's objectives.

Although DOE's current state of activities with regard to energy in waste-
water treatment can be summarized as being in a planning stage, there are several
additional efforts which have some relevance here, three of which I would like
to mention: 1) along with EPA, DOE is funding the development of a manual for
energy conservation and recovery in municipal wastewater treatment plants. It
will be published as part of the EPA Technology Transfer series, 2) DOE is
participating in the Reedy-Creek Project, which was previously discussed in
this conference, 3) the DOE is sponsoring a conference on the subject of Energy
Optimization of Water and Wastewater Management to be held in New Orleans on
December 10-13. Announcements on the table in the back of the room describe
the conference further.

Finally, I would like to address the question: Where does wastewater aqua-
culture lie in DOE's current plans? Frankly, the answer is that it is not
currently a part of the plans. This does not imply that DOE is not interested
but I believe a stronger arguement has to be made concerning the energy conser-
vation and recovery opportunities which can arise from the use of wastewater
aquaculture systems. I am convinced that there are such opportunities. Some-
time back, while providing technical consulting support to DOE, I worked towards
achieving DOE participation in the Reedy Creek (Disney World, Florida) aqua-
culture effort. I felt that there was sufficient energy conservation potential
in such systems to warrant DOE getting its feet wet and yet not getting bogged
down. I also believe we now need to quantify the energy conservation and recov-
ery in wastewater aquaculture units as a basis for comparison with conventional
processing units. Implicitly, the use of aquaculture processing units should
result in the use of less energy than conventional treatment, assuming effluent
limitations can be met. We know that about 80% of the sewage districts in the

419

U.S. have treatment facilities with capacities of one million gallons per day
or less (this capacity serves about 10,000 municipal residents). Because of
economy-of-scale principles, aquaculture-based treatment systems may become
attractive for some of these smaller plants, particularly in light of the sched-
ule for treatment requirements. The potential energy conservation and by-product
utilization characteristics of aquaculture-based wastewater treatment may further
the acceptance of such systems as alternative technologies.

Thank you.

420.

RESOURCE RECOVERY FROM WASTEWATER AQUACULTURE

Larry 0. Bagnall, Associate Professor of Agricultural Engineering,
Institute of Food and Agricultural Sciences, University of
Florida, Gainesville, Florida 32611

ABSTRACT

Removal and recycling of the nutrients and other components in
the wastewater aquaculture system are completed by harvesting, pro-
cessing and utilizing the aquatic organisms in which the nutrients are
collected. Aquatic species grown in wastewater have been experimen-
tally used for food, feed, fiber, fertilizer and energy. Some of the
processes and products appear to be technologically and economically
feasible on an operational scale.

INTRODUCTION

Agriculture has traditionally taken the elements of soil, water,
air, nutrients, sunlight and selected organisms and used them to
produce food, feed, fiber and energy. Aquaculture, by extension,
takes the same elements, usually excepting soil, and produces similar
products. The technology of agriculture, developed over millenia in
diverse environments, has established preferred species, cultural
practices, harvesting and processing procedures, storage and marketing
structures. With the possible exception of fisheries, aquaculture has
established none of these.

In the context of this conference, the principal product of the
was tewater aquaculture is pure water. The disposition of what was
referred to in one of the preliminary program drafts as "by-products"
is an annoying, but secondary, problem. Properly managed, they could
conceivably be resources of as much economic importance as the water.

In agriculture and ordinary aquaculture, an important objective
is to maximize production of a usable or salable biological product,
given available resources. Species and varieties are selected and
bred on the basis of utility and productivity. The most productive
aquatic species are usually considered to be weeds because of their
great productivity and lack of apparent utility. "A weed," according

421

to Emerson, "is a plant whose virtues have not been discovered." The
virtue that has been discovered, and is the basis of this conference,
is the ability of these species to rapidly absorb and immobilize vast
quantities of pollutants. Another virtue is the concentration of
energy and nutrients, which only is realized by the application of the
developing techniques of management, harvesting and processing.

Aquatic Plant Aquaculture

Plants are the primary producers in all agricultural and aquacul-
tural systems. They combine the raw nutritional elements with the energy
of the sun into chemical and physical structures usable by "higher" spe-
cies. Subsequent use and passage of the elements and energy up the pro-
cessing and consumption chain always results in some loss of matter and
energy, though sometimes with some enhancement in the quality of the
residue.

The ideal plant for wastewater aquaculture with resource recovery
rapidly produces high areal dry matter density, is insusceptible to
chemical, disease, cold or insect damage, and is readily and cheaply
harvested and processed into a readily accepted product. And doesn't
exist. There are some species, however, that have enough of these
virtures to make the other characteristics worth tolerating or improving.

Some species of plants can be harvested by appropriately selected
herbivores, such as fish. If a marketable species of fish is used, it
can be harvested directly. If not, carnivorous species can prey on
the herbivores in a managed system and the carnivores can be harvested.
Each succeeding step in the food chain introduces some loss of nutrient
harvest, but the economic return of the higher quality of harvested
nutrients may offset this.

The cultural system must be designed to accomodate the harvesting
system if resource recovery is to be economically feasible. Though the
harvesting requirements for different species vary, such considerations
as channel width, water depth, run length, freedom from obstructions,
bearm width and bearm height may be important. Space and facilities
for onsite processing and utilization may have to be provided.

Systematic and efficient direct harvest of the plants and asso-
ciated organisms has the greatest potential for maximizing recovery of
resources. Direct harvest can be manual or mechanical, depending on
the size of the cultural system and the level of local technology.
Harvesting is simply removing the plant from the water and may include
cutting in the case of matted or rooted macrophytes, elevation of all
macrophytes, and concentration of all species. Though it is usual to
harvest small quantities of the crop at frequent intervals, complete
removal and re-seeding may be practiced in some cases. The harvesting
rate and frequency may be established before the harvesting system is
designed.

422

.PLANTSIC HARVEST PROCESS by PRODUCT - E UE
A. PLANTS
1113

Harvested aquatic plants are too wet, too large or too small, and
too biologically or chemically unstable to be conveniently and economi-
cally handled, stored, and utilized. Large plants may be chopped and
small plants aggregated to reduce their intractibility. Water, and hence
mass, may be reduced by drying, pressing or centrifuging. Additional
processing may be applied to convert the plants to a form acceptable to
the proposed utilization.

Water Hyacinth Harvesting - Processing - Utilization

Much of the wastewater plant aquaculture reported at this confer-
ence has involved water hyacinth (Eichhornia crassipes (Mart.) Solms).
Most of my research on harvesting, processing and utilization of
aquatic plants has involved water hyacinth grown on municipal or
animal wastewater or from natural sites. Consequently, most of this
paper will be the systems, components and products related to water
hyacinth.

Water hyacinth most effectively meets the proposed productivity
criterion of the ideal wastewater aquaculture species. It is also
relatively insect and disease resistant, outgrowing its parasites, but
is not very cold or chemical resistant. (A problem relative to its
use in wastewater aquaculture may arise from indiscriminate intro-
duction of more virulent biological control agents, which may require
eradication of all natural stands within some radius of a cultured
crop to prevent a destructive epidemic.) It is also large, very wet,
bulky, intractible and has virtually no direct utility.

A network of possible water hyacinth processes and products is
shown in Figure 1. Harvesting and chopping are precursors to all of
the other processes and all of the products. Chopping is helpful but
not required for the soil amendment products. The chopped plants may
be applied directly to land, composted to stabilize and reduce mass,
digested to produce methane, pulped to produce paper, or pressed to
reduce moisture content and produce a highly reactive protein-mineral-
sugar juice. The juice may be separated to recover a high quality
feed-food protein-mineral concentrate or digested to produce methane.
The pressed fibers may be ensiled with appropriate additives or dried
to produce a granular feed component.

Harvesting

Water hyacinth stands are typically 100 to 200 T/A of plants 18
to 42 inches tall. The plants may be relatively detached or tightly
matted. Containment or restraining devices are needed to force the
detached plants into a harvesting mechanism and vertical cutters may
be needed to separate manageable lots of matted plants for orderly
harvesting. Water hyacinth is most easily and effectively harvested
by a conveyor projecting into the water below the root level. Usually
flat wire steel conveying belt is used, but other types, including chain
and flight have been applied successfully. In stationary designs a

424,

PAPER METHANE FEED-FOOD

PULP DIGEST -TSEPARATE DRY GRAIN

CHEM ICALS I JUICE MEX

AQUBAT"Z
PLATC HARVEST -- CHOP PRESS j3FIBER DRY PELLET

CHO

COixdPOST FNSII

SOiL A:-'j V) HIND N\1 ZNT - S"LAGE DRY FEED

boat is used to push mats of plants to the conveyor and an overhead
reel is used to crowd the plants onto the plants onto the conveyor,
reducing slippage at the turbulent conveyor-water interface. In
mobile designs, the pusher boat is unnecessary and the reel not as
important, as the motion of the harvester, particularly into a packed
mat, provides the crowding and feeding actions. Conveyor speed is
typically 50 to 100 ft./min. and conveyor width is 4 to 40 feet.
Estimated energy cost for this type of harvester is 0.3 HP hr/T and
estimated economic cost is $0.12/T.

A new drag conveyor harvester design is being developed at the
University of Florida which should have a much higher capacity than
existing designs, reducing energy consumption slightly and economic
cost substantially but improving flow over the conveyor-water interface.

Efforts have been made to harvest water hyacinth by pumping and
have had various degrees of success. The advantage of this type of
harvester is its simplicity, low initial cost, ease of handling the
harvested product, and expected ease of feeding. The factors that
have prevented successful application so far have been high energy
requirement, disposition of the harvested plants and bridging of
plants in the entry flow. It may be necessary to pre-shred plants to
assure reliable feeding. It will be necessary to substantially reduce
surplus water required to carry the plant fragments (presently 10 lb.
of water/lb. of wet plant material) to reduce energy requirements and
disposal or recovery costs.

Chopping

Harvested water hyacinth bulk density is 5 lb/ft3 or less. The
plants are usually interconnected and en masse are exceedingly difficult
to handle manually or mechanically. The logical means of improving
density and handling characteristics are to bale or to chop. Energy
requirement for baling is low, densitites around 50 lb/ft3 can readily
be achieved, and bales can be readily handled mechanically. However,
wet water hyacinth bales are mechanically unstable and become less
stable with time, decay putrefactively (they stink), and must be
subsequently chopped in almost any resources recovery system for
supply to subsequent processes.

The plants can be readily chopped with crimpers or agricultural
flail or cylinder-shear bar choppers. Chopping usually increases bulk
density to 15-20 lb/ft3. Crimpers accept to full width of the harvested
mat, but must be designed with more clearance than typical agricultural
crimpers to accept the higher volume of plants. A current design being
developed at the University of Florida uses 12 inch diameter rolls with
six 3 inch high sharpened flights, a loading of 100 lb-in of roll width
and a peripheral speed of 200 ft/min, twice the conveyor speed or the
harvester to which it is attached. Crimpers used so far have increased
density to 15 lb/ft3, but have not broken the plants sufficiently to
provide a regular fluid stream.

A426

Fluid choppers have been used by several harvester builders.
One uses a full-width flail above the elevating conveyor, shredding
the plants before they are tumbled or turned in any direction. The
other drops the plants onto a narrow cross-conveyor which carries
them under a narrower flail. The advantages of the former system
are that the chopper is fed more uniformly, the plants are chopped
before they have a chance to tangle and entwine, and the benefits of
lower volume accrue throughout the system; the advantages of the
latter system are that a smaller chopper is required and less material
passes through the gap between the flail and the conveyor. The
material from either system is not very uniform, which may cause some
difficulty with some subsequent processes, but is much more fluid than
that from the crimper.

Cylinder-shear bar choppers use feed rolls or aprons to control
the speed and orientation of the material coming to the cutting
surface,, and consequently produce the finest and most uniform product
of the three types. However, because of the bulk of water hyacinth
and the flacidity of its roots, commercial agricultural choppers are
only marginally adequate. We were able to chop 28 T/hr in a 16 in
wide by 24 in diameter chopper, with energy requirement of 0.2 hp hr/T,
but only by careful alignment of the feed. A cylinder-shear bar
chopper specifically for water hyacinth is being developed at the
University of Florida. It features greater width, lower speed and
higher throat opening than typical agricultural choppers and uses
feed aprons instead of feed rolls. Energy requirement is expected to
be the same to slightly lower than found in earlier trials and
capacity and reliability higher.

Cost of chopping is about $0.06/T, based on costs and capacities
of cylinder-shear bar chopping. Differences between the costs
(energy and economic) of the three types of choppers are unknown, but
equipment is being assembled at the University of Florida to determine
these differences.

in almost all instances (all instances that I can think of), the
harvesting and chopping mechanisms should be incorporated into a
single maching. Capacity will be maximized, machine size minimized,
reliability improved, and subsequent system and component costs
reduced. Energy cost of combined harvesting-chopping should be about
0.5 hp hr/T and economic cost should be $0.16/T.

Soil Amendment - Compost

Intact or chopped water hyacinth, fresh or composted, may be
applied to soil as a source of fertilizer element as a means of
improving soil structure and water balance. The fresh plants contain
about 3 percent nitrogen, 0.7 percent phosphorous and 2 percent potassium
or a dry basis, but the dry matter constitutes only 5 percent of the
fresh mass. About 1/3 of the nutrients are leached out in the

427

composting process, but 80 percent of the water is lost as well and
the volume is reduced 90 percent, so the mass and volume concentration
of nutrients is higher. The water hyacinth fiber has excellent water
retention and will improve the water retention of sandy soils.
Incorporated properly, it will bulk clay soils, improving porosity
and drainage. The principal limitations to its use as a soil amend-
ment are its occasionally high salt content and its high water
retention, both of which are only serious problems when it is used
at very high rates, such as in potting mixtures.

Intact or chopped plants compost redily. Chopped plants decompose
more rapidly and produce a structureless humus within 30-60 days with no
additives or attention. Intact plants decompose more slowly, with
some parts drying and forming resistant structures which retain their
identity. Under conditions of great depth or high continuing rainfall,
chopped matter may become anaerobic and require turning or forced
aeration. Crimping or flail chopping, which produce coarse fragments,
appears to consistently compost better than fine-chopped or intact
plants.

Several aquatic plant harvesting investigators and operators have
reported that householders and farmers readily accept fresh or com-
posted aquatic plants for potting, flower beds and gardens. One
entrepenuer in Florida had a market developed for a water hyacinth
compost based potting soil.

Paper - Pulp

Paper and related products have been made from water hyacinth.
Properties have generally been good for packaging applications.
Potential is reportedly limited by low fiber yield and slow drainage
rate, both of which would render water hyacinth non-competitive with
traditional fiber sources. Many characteristics, including drainage,
are improved by blending with coarser pulp, such as pine. Nolan
feels that water hyacinth paper production would be uneconomical in
industrialized countries with high labor costs and capital inputs.

Fuel Production

Biogas containing 63 percent methane can be readily produced
from water hyacinth and its juice (press liquor). Wolverton reported
yields of 370 1 of biogas (63 percent methane) per kilogram of
volatile solids from chopped water hyacinth in a batch digester. A
200 1 continuous digester at the University of Florida is currently
producing 120 i/day of 63 percent methane biogas from 24 kg/day of
water hyacinth juice (2 percent total solids). Conversion is 500 1
biogas/kg volitile solids.

428

Pressing

Harvested or chopped water hyacinth are 95 percent water. By
pressing, 35 to 75 percent of the water can be removed in a few
seconds. The amount of solid removed with the water depends on
pre-aeration and press action and usually increases with increasing
water removal. Static pressing of intact plants can remove 35
percent of the water with almost no solids removal. Aggressive
screws pressing can remove 75 percent of the water and 30 percent of
the solids.

Most of our pressing research has involved continuous flow
screw-presses of moderate capability which remove 50 to 70 percent
of the water and 10 to 25 percent of the solids in a light weight
screw and cage. The juice passes out through the screen surrounding
the cage and is collected for additional processing. The fiber is
fine, friable, handles easily and can be readily dried or ensiled.
Intact plants can be pressed, but press capacity is usually 3 to 4
times as great when operating on chopped plants, due to their higher
density and greater fluidity.

Screen pressing requires about 2 hp hr/T of chopped plants and
costs $5.761T.

Juice Concentration

The juice from the screw-press contains about 20 percent of the
total solid of the fresh plants. By analysis it is primarily protein,
salt and sugars. Up to 80 percent of the total solids and 90 percent
of the crude protein in the juice can be recovered by centrifugation,
fine filtration or 24-hour sedimentation. The 24-hour sedimentation
is enhanced by the suppression of pH1, and consequent acid precipitation
of protein, due to natural fermentation. The juice sediment can be
quickly solar dried on a screen. The supernatant, containing the
sugars, can be digested to produce methane. As an alternative to
nutrient recovery for feed or food, the juice can be digested for
methane and the spent fluid used for fertilizer.

Ensiling

The pressed fiber can be ensiled by mixing with a fermentable
(sugar or starch) carbohydrate, such as corn or dried citrus pulp,
and packing into a nearly airtight container. As an alternative to
pressing, the average moisture content has been reduced by dilution
with dry material, such as straw, paper, or wood fiber, or by wilting.
In any case, an average moisture content between 50 to 85 percent,
wet basis, and adequate carbohydrate for rapid fermentation are
required.

Animal acceptance of properly ensiled water hyacinth has been
very good and performance has been satisfactory.

429

120

pH 6- -H 6. 1 t

Th ~~H =65.12 - .162 t 0
0 2 4 8 24
HOURS
FIGURE Z _FFECT OF TINME ON HYACINTH JUICE pH

Energy cost of producing silage, including harvesting, chopping,
pressing, and silo filling is 2.7 hp hr/T of fresh plants or 68 hp
hr/T of stored dry matter. Economic cost is $17/T of fed dry matter,
which is competitive with traditional feeds.

Drying

Pressed or pre-wilted water hyacinth may be dried in any type of
traditional forage dryer to produce a dried feed component. Energy
cost of drying in a traditional type of rotary dryer is 960 J/g of fresh
water hyacinth or 24,000 J/g of dry feed. Economic cost of producing
dry feed is $117/T, which is unreasonable.

As an alternative to traditional drying, solar drying can
eliminate to fuel cost and reduce the cost of production of dry feed
to $20/T, competitive with existing feed sources.

Dry feed was not as well accepted as silage, and animals did not
perform as well on it. Water hyacinth in any form should constitute
no more than about 20-30 percent of an animal diet, due to excess
mineral intake and mineral imbalance suppressing total feed intake.

Systems Costs & Returns

The cheapest method of disposal is land application, with or
without composting. As level of processing increases, the value of
product increases, but not always uniformly or at a rate which keeps
up with production costs. A feed market may be difficult to esta-
blish and maintain, partly due to cost and partly due to social-
psychological factors. Biogas may be an easy market to establish
and maintain. Energy of producing dry feed by traditional methods
exceeds the energy content of the feed.

431

RAFTER
R OOF
SUPPORT
COLUMN

TRUSS

WIND-ASSISTED SOLAR DRIER
SIDE VIEW
SCALE-. 1/16
LOB UF AGE 790529

432

15.

10-

TYPICAL SOLAR DRYING CURVF
PRESSED WATER HYACN-rH

N
E
"I
m~~~~

:3 5-

LAL

0 1 2 3
DAYS

433

15�1

SOLAR DRYING PRESSED WATER HYACINTH
10.~ FORCED vs PASSIVE

FORCED
PASSIVE-1

'li\ ~~~~~~~150

0
tL

3~~~~~~~~3
1- s.

DAYS.

434

SOLAR DRYING PRESSED WATER HYACINTH
EFFECTS TURNIING & HALF-LOADING
10-,
TURN
HALF LOAD

:a \N
' %
E

j~~~~~~~~~ 4
j)" \

'~\ \

0 2 3 4
DAYS

435

WA�ERAYACWTH SOLAR DRYING TIME., DAYS

2
CONTiROL (Scfmlft ,no cover 3
pressed, no shade.
2.5 lb/ft , no recirculation)

VnEOtIY, 0 cfm/tt2 8.

2.5 ctm~e~ ~lft a

COVER

TREATMENT INTACT ?"$ 2

CHOPPED 3

LHADING t25 j b/ I.4

5 lb/ft2 17 1

REC IRCULAlION

PARTIAL (Znd DAY) 2

VELOCITY(O n SH4ADING

COVER x LOADING (1-.25)

COVER x RECIRCUILATION

PARTIAL (2nd DAY) 4-8

436

MIINMUM AREAS TO SOLAR DRY WATERHYACINTH
PRODUCTION FROM ONE ACRE (4000 Ib/da)
5 cfm/ft 2

IN4TACT 2.5 lb/ft2140
1600 i -d

CHOPED.2.5lb/ft 21,0
1600 t"j

PRESSED, 2-S Mi/tt2BEE 4
BOO n 2da

t.25 lb/ft 2 ~ ~ 50

5 lb/ft ~wo
400 ft2-Ida

437

24000

PROCESSING ENERGY
J/g OF DRY FEED

16000

300-

200

100-� , I iL

200 'H EC EC H.' EC .a EC HY
A_4t"-> C>-:E ?Z-CSS PELLET
~50~~"~"-~- -

�0~J 26

$140- PROCESSING COST 138
$/Mg OF DRY FEED
122
$120- 117

$100-

$80- 178

$60-

40
$40-

$20- I7

7
411
EC_ l EC HC VV ECIF EC HV
H A RVE S' OC- PRESS IL AG DRY DRY PELLETS

ENERGY FROM WASTEWATER AQUACULTURE SYSTEMS

John R. Benemann, Ph.D. Ecoenergetics, Inc.
President 2038 Pleasants Valley Rd.
Vacaville, Calif. 95688

INTRODUCTION

The utilization of aquatic plants in wastewater treatment [1]
raises the issue of the most suitable uses for the plant biomass
produced during such processes. In this presentation the utilization
of wastewater-grown aquatic plants as a feedstock for conversion to
fuels is discussed.
Fuels from biomass is considered one of the most promising solar
energy options, with wastes and residues alone being able to generate
enough fuel, using near-term collection and conversion technologies,
to meet about 5% of current U.S. energy needs [2]. (Current U.S.
energy use is approximately 80 x 10's BTU/year.) The collection and
use of existing "non-commercial" forest resources could probably
double the biomass resource base [3]. The production of fuels from
biomass produced on "energy farms" has a large potential,but the
economic and environmental constraints of such systems may be severe,
such that these are generally considered long-term options of un-
certain impact. This is particularly true of aquatic biomass energy
systems. The author has recently reviewed the cultivation of aquatic
plants such as microalgae, water hyacinths, and marsh plants, and
their conversion to fuels [4] and concluded that the only near-term
options for energy from aquatic biomass would involve wastewater
aquaculture systems and, possibly, residues from the production of
higher-value chemicals, animal feeds, or foodstuffs.
In the specific case of municipal wastewater aquaculture, the
conversion to fuels of the aquatic biomass generated is likely to be
their highest economic use, as utilization as animal feeds will be
restricted in most cases by public health considerations. This is
probably also true for aquatic foodchains and for use of waste-grown
aquatic plants as feeds in conventional husbandry. This does not
imply that public health problems are necessarily inherent in waste-
water aquaculture. The traditional experience with sewage-fed fish
ponds in the Far East and even Europe has not revealed any major
public health hazards. However, in the context of the intensive

441

(rather than extensive) wastewater treatment processes necessary in
the U.S., the potential for contamination by heavy metals and toxic
organics, and more rigorous standards and cultural attitudes prevalent
in this country-, it may be expected that the recycling of municipal
wastewater-grown organisms directly into the human food chain will
require a very long period of testing before it finds acceptance.
Such restrictions do not apply to animal or food processing wastes.
Thus, this review will be limited to energy from municipal wastewater
aquacul ture.
Another factor in favor of the use of waste-grown aquatic biomass
as an energy source is the established practice of anaerobic digestion
of sludges in municipal wastewater treatment plants. The aquatic
biomass may be considered a new type of sludge that could be handled
in a similar way to other sludges. It should be noted that sludge
handling and disposal is often the single largest expense in a modern
municipal wastewater treatment plant. Thus, the aquatic biomass
may be a liability rather than an asset. However, this is not certain
as experience in the handling, digestion, or conversion of aquatic
biomass, and disposal of the residual sludge, is practically non-
existent. This review must draw on other types of experiences and
be speculative in tone. It starts with a brief review of aquatic
plants in wastewater treatment to allow a determination of the likely
supply and composition of the aquatic biomass available for energy
conversion processes.

AQUATIC PLANTS IN WASTEWATER TREATMENT

Three types of aquatic plant systems are most often considered
in wastewater treatment--microalgae, floating plants, and emergent
plants. The microalgae have the advantage of producing dissolved
oxygen that is readily utilized in meeting BOD5. Their cultivation
is, however, difficult to control, and they are even more difficult
to harvest. Floating plants--water hyacinths and duckweeds, prin-
cipally--are much more easily harvested, and their cultivation
presents few known problems. They can serve in wastewater treatment
in combination with mechanical aeration or microalgae. Their
principal functions in secondary treatment appear to be in providing
a cheap cover which prevents wind mixing and algal blooms, thus
allowing settling of suspended solids and clarification of effluents.
Water hyacinths may also exhibit significant removal of suspended
solids through absorption-filtration by their roots. Whether water
hyacinths could remove soluble BODs by direct uptake of organics is
uncertain. The stems of marsh plants provide a large, shaded surface
area below the waterline which may allow microbial colonization and
activity. Submerged plants are found in many oxidation ponds but
are of uncertain applicability to wastewater aquaculture.
These aquatic plants have relatively high productivities and
high nutrient content. The literature data (see Refs. 4 and 5) are
summarized in Tables I and 2. These data are based on a detailed
review of the literature, exemplified by Table 3 which presents
selected references for productivity of water hyacinths. By multi-
plying productivity with nutrient composition, it is possible to
calculate the removal of nutrients, e.g. tertiary treatment, affected

442

TABLE 1

RANGE OF PREDICTED BIOMASS PRODUCTIVITIES
FOR AQUATIC PLANTS
(from Ref. 4)

Aquatic Plant Range of Productivities
MT/HA/yr-

Microalgae Green algae 40-80
Microalgae Blue-green algae 25-50

Submerged Macrophytes (Hydrilla, etc.) 25-50

Water hyacinths 60-120
Floating Plants Duckweed 20-40
Azolla 20-50

Emergent Plants Phagmites 40-80
Sparti na 25-50

*Lower value represents currently expected productivities in
wastewater treatment ponds; higher value refers to future
possible yields under favorable conditions.

443

TABLE 2, COMPOSITION OF AQUATIC PLANTS*
% OF DRY WEIGHT

PLANT TYPE NITROGEN PHOSPHORlUS POTASSIUM ASH
MEAN (RANGE) MEAN (RANGE) MEAN MEAN

MICROALGAE 5.8 (1.2-1,4) 0.7 (O.0-3.0) 1.7 14.2

SUBMERGED 2.6 (1.7-4.6) 0.45 (0.03-0.9) 2.2 20.8

FLOATING 4.0 (1.5-7.0) 0.63 (0.1-1.8) 2.5 14.1

EMERGENT 1,7 (0,.9-2.3) 0.18 (0.09-0,32) 2.1 8.6

*from Reference (5)

TABLE 3,STANDING BIOMASS AND PRODUCTIVITY OF EICHORNIA CRASSIPES*

AUTHOR LOCATION SEASON BIOMASS PRODUCTIVITY COMMENTS
g/m2 g/m2/day

PENFOUND LOUISIANA SUMMER 1478 12.7-14.6 NATURAL POPULATION
11 II
ODUM FLORIDA MAY -- 10.3 (max. productivity)

RYTHER FLORIDA YEARLY VARIABLE 24.5 MANAGED CULTIVATION
(5.4-52)
YOUNT &
CROSSMAN FLORIDA YEARLY VARIABLE 5-54 FERTILIZED POND

BOYD ALABAMA AUGUST 2130 17.7 FERTILIZED POND

BOYD ALABAMA SEPTEMBER -- 27.6 FERTILIZED POND

WOLVERTON & MISSISSIPPI APRIL- 1090 87.5 20 SEWAGE POND
MCDONALD JUNE

*from References (6-10, 15)

by the growth of the aquatic plants. This can be quite considerable.
For example, if water hyacinths are assumed to produce 100 dry metric
tons/hectare/year (MT/HA/yr) and contain 3.6% N, then one hectare
would be able to remove all the nitrogen in a flow of 0.25 million
liters per day of a typical wastewater flow (assuming 40 mg/L total
N in sewage).
Unfortunately, such a calculation ignores the large, roughly
ten-fold seasonal variations in productivities for all aquatic plants.
Thus, maximal productivities for water hyacinths in Florida are almost
50 g/m2/day in summer but drop to 5 g/m2/day in winter (Table 3). One
reason for this seasonal variation, in the case of water hyacinths,
is their well-known sensitivity to cold. This may be overcome with
greenhouses. However, greenhouses would further cut down on the low
winter time insolation. Thus, greenhouses will help in the over-
wintering of the water hyacinths and in extension of their geographical
range, but they cannot completely overcome the large seasonality in
productivity. Other aquatic plants exhibit similar seasonal produc-
tivities.
Several alternatives are possible to overcome the limitations on
tertiary treatment due to plant seasonality--maximization of nutrient
removal processes not dependent on plant growth, storage of sewage
in winter, operation under yearly and seasonal discharge standards
(rather than the current monthly and weekly standards), or combinations
of the above. Processes for nutrient removal not involving plant
growth include volatilization of ammonia and nitrification-denitri-
fication, absorption by soil or on plants, and chemical precipitation.
All are known to occur to varying degrees in most wastewater aquaculture
systems and may be increased through various operational strategies.
Another approach is to build up an inventory of nutrient-deficient
plants in late summer or fall which would take up nutrients during
the winter. Obviously, this would require rather sophisticated control
of operations. Storage of partially treated effluent in the winter
is another possibly attractive and low-cost alternative.
The seasonality of plant growth also has a significant effect on
the design and operation of any biomass conversion technology and the
use of the fuel produced. It is obviously best to maintain as steady a
production rate as possible. One method is to "draw down" the standing
aquatic biomass crop in winter and build it up in summer. This also
fits with the strategy of building up a nutrient-starved biomass in
summer. This is not feasible with microalgae which have a very small
standing biomass and is probably limited in the case of marsh plants
which exhibit strong seasonality in their pattern of photosynthesis
and relative shoot and rhizome growth. For water hyacinths, greater
flexibility is possible with plant densities higher than optimal
being allowed to build up in fall to be used up in winter. The recent
quantitative work by Ryther et al. [8 ] may allow the estimation of the
optimal strategy.
The amount of biomass produced by a wastewater aquaculture system
depends not only on the season, the specific plant selected, or the
management strategy, but also on the size of the system per unit flow.
This is, at present, an uncertain quantity for most systems. Con-
ventional oxidation ponds loaded at 50 kg BOD5/HA/day require 5 HA
per million liters per day of sewage flow (assuming 250 mg/L BOD5)

446

(equivalent to about 45 acres per MGD). Such systems are, however,
very poor and erratic biomass producers and, at any rate, should
not be included in the definition of wastewater aquaculture [1].
High-rate oxidation ponds (shallow, mechanically mixed) may be loaded
at a yearly minimum of about 100 kg BOD5/HA/day in California, and
algal removal, accomplished by a two-day flocculation-sedimentation
process, appears very promising [11]. During 1978 and 1979 the pro-
duction and harvestability of microalgae grown in two 0.1 hectare
pilot-scale oxidation ponds were determined. The data indicated that
high productivities and harvestabilities, achieved by a low-cost
sedimentation process, are possible with such a system [11]. How-
ever, the reliability and effectiveness of such a process remains to
be demonstrated in field-scale tests.
Aerated water hyacinth ponds could, in principle, be quite
small, with size only restricted by the need to provide a settling
basin for suspended solids removal. Currently, design criteria are
not well established. However, Solar Aqua Systems, Inc. has designed
a 0.35 MGD (1.3 x 106 L/day) plant at Hercules, California, with a
total pond size of 1.5 acres (0.68 hectare), giving a size of about
1 hectare per 2 x 106 L/day. This is about five times the loading
achievable in high-rate microalgal ponds under similar climatic
conditions. Dinges suggests a one-acre water hyacinth pond to
remove algae from the effluent of a waste stabilization pond serving
3,000 people (0.3 MGD). This amounts to increasing the size of a
typical facultative oxidation pond by only 10%. The size of marsh
systems are not well established. In all cases the objective of the
treatment (e.g. 30/30 or 10/10 BOD5/SS standards, tertiary treatment,
polishing, etc.) will set the size of the system. (See other papers
in These Proceedings for detailed discussions.)
Table 4 summarizes the key points brought up in the development
of municipal wastewater/aquaculture systems. It is clear that a
number of uncertainties exist about the amount of aquatic plant
biomass that will be produced by municipal wastewater aquaculture
systems. The exact size of the systems is not yet determined,
neither is the yearly variation in biomass productivity, optimal
standing biomass, or nutrient contents. The harvesting of the
biomass will not be addressed here except in that it is the major
problem with microalgal production, but only a relatively minor one
with higher aquatic plants. In the next section the use of the
aquatic biomass as an energy Source is discussed.

CONVERSION OF AQUATIC PLANT BIOMASS TO FUELS

The high moisture, high nutrient, and low lignocellulose
content of most aquatic plants make them ideal substrates for anaerobic
digestion. As this is already a widely used technology in municipal
wastewater treatment, it will be emphasized in this discussion. How-
ever, marsh plants may be dried, either prior or after harvesting, and
can exhibit high lignin content. Thus, thermochemical conversions may
be most applicable but will not be discussed in this review.
Existing experience with anaerobic digestion of aquatic plants
is very limited. Microalgae harvested by sedimentation from a high-
rate oxidation pond have been recently subjected to anaerobic digestion

447

TABLE 4
GENERAL CONCLUS IONS ON WASTEWATER AQUACULTURE SYSTEMS

I. YEAR-ROUND PERFORMANCE WILL BE VARIABLE, BEING SEASONALLY
(TEMPERATURE AND LIGHT) DEPENDENT.
2. THE PHYSICAL PRESENCE OFTHE PLANTS MAY BE AS-- OR MORE--
IMPORTANTTHANTHEIR BIOLOGICALACTIVITY.
3. BACTERIAL ACTION IS A PRIMARY FACTOR IN SUCH SYSTEMS
(E.G., BOD5 REMOVAL, DENITRIFICATION, ETC.).
4. PHYSICOCHEMICAL PROCESSES (SOIL ABSORPTION, PRECIPITATION)
MAY OFTEN EFFECT MORE NUTRIENT REMOVALTHAN THE PLANTS.
5. PLANT BIOMASS PRODUCTION MEANS HARVESTING AND DISPOSAL
PROBLEMS.
6. EVAPORATION AND TRANSPIRATION CAN SIGNIFICANTLY INCREASE
TDS AND DIMINISH WATER REUSE.
7. LONG-TERM RELIABILITY CANNOT BE GAUGED FROM SHORT-TERM
EXPERIMENTS. SINKS MAY FILL UP.
8. ENGINEERING DESIGN CRITERIA IS LACKING. EVEN IF AVAILABLE,
ONE-TO TWO-YEAR PILOT PLANTS ARE REQUIRED.
9. LAND AREA REQUIRED IS CRITICAL FACTOR. POTENTIALLY, SUCH
SYSTEMS ARE OF LOWER COST AND NET ENERGY CONSUMPTION.
10. EFFLUENT STANDARDS AND PERMITS MUST REFLECT CAPABILITIES
OF TECHNOLOGY (YEARLY AND SEASONALY STANDARDS DES I RABLE).
11. ESTHETIC AND ECOLOGICAL IMPACTS FAVOR THESE TECHNOLOGIES.
12. MORE RESEARCH IS REQUIRED.

448

in a very lightly loaded reactor (due to the low solids concentra-
tions, 1 to 2%, of the settled material). The results indicated
that the microalgae could be readily digested, producing 400 L of
digester gas (65% methane) per kg of volatile solids added (minimum
detention time about 18 days) [12]. However, microalgae harvested
with alum at the City of Sunnyvale have not been successfully digested
due to inhibition by the alum [12]. Prior work by Golueke and
Oswald [13,14] indicated that alum-harvested algae could readily be
digested. The difference can probably be ascribed to flocculation.
The production of methane gas from water hyacinths has been
studied by a number of different groups; however, no detailed data are
available. Wolverton et al. [15] reported in 1975 on five laboratory
batch experiments in three-liter Erlenmeyer flasks fed with 300 to
878 g of wet weight greenhouse-grown, chopped water hyacinths plus
800 ml of water. The flasks were seeded with an extract of anaero-
bically decomposed plants and shaken once a day. Gas production was
followed for up to four months. Cumulative gas production was
highest--ll ml CH4 per 9 wet weight (g.w.w.)--at the lowest loading
(300 g wet weight). Surprisingly, absorption of 5.4 mg nickel and
6.87 mg of cadmium on 542.8 g w.w. water hyacinths gave high methane
yields (11.3 ml CH4/g w.w.) and 91.1% methane in the gas phase. This
is an unexplained phenomenon which warrants rechecking. A. Johnson
reported [16] on experiments in Taiwan during 1976 with anaerobic
digestion of vegetable matter using a two-phase digestion system.
Water hyacinths were digested in two smaller batch digesters; however,
gas production data were not taken. Lecuyer and Marten [17] presented
an "economic assessment" of a biogas production system based on water
hyacinths, assuming 130 MT/HA/yr of dry weight yield of plant matter
and a 220,000-acre pond system. Gas production yields were "expected"
to be six scf of methane per dry lb of water hyacinth; however, no
data were actually collected.
Chin and Goh report on experiments in Singapore [18] with 12-
liter digesters fed 290 g w.w./L of chopped water hyacinths, corres-
ponding to a 1.8% volatile solids loading. The digesters were
operated at 37�C and mixed and fed daily for over sixty days with
29 g/L (10-day retention time) and 14.5 g/L (20-day retention time)
of wet weight hyacinths. Gas compositions averaged 54% CH4 and CO2
with steady-state volatile acids at 440 mg/L and 320 mg/L volatile
solids destruction of 56% and 60% and gas yields of 644 ml/g and 673
ml/g for the 10-day and 20-day retention time digesters respectively.
This is the only published data on continuous anaerobic digestion
of these plants. Loading rates were rather low; however, the con-
clusion may be reached that water hyacinths are a good substrate for
anaerobic fermentations. This is also concluded from more detailed,
but still unpublished, studies on anaerobic digestion of water
hyacinths carried out by Klass and coworkers at the Institute of Gas
Technology [19]. They found that sewage-grown plants which have a
higher nutrient content digest better than natural populations.
Results are reportedly comparable to those obtained by anaerobic
digestion of giant kelp [19]. Ryther [10] has also carried out
experiments on anaerobic digestion of water hyacinths using 0.16 m3
digesters fed three times a week with finely shredded materials, with-
out mixing, at a loading rate of 0.8-1.0 g/L/day. Reportedly, the

449

Dynatech R & D Corp. and Solar Aqua Systems, Inc. also have carried
out anaerobic digestion experiments with this plant, but no informa-
tion is yet available.
This review of the literature reveals that much more informa-
tion should be available by next year, and that, for now, anaerobic
digestion of water hyacinths and microalgae can be assumed to proceed
without significant difficulties and at rates comparable to those
observed with sewage sludge. Data on anaerobic digestion of other
aquatic plants is very sparse. Of the submerged plants, Elodea was
reported by Koegel et al. [20] to be anaerobically degraded while
Hydrilla has been studied by Dynatech (no data available). No
references to anaerobic digestion of marsh plants have been found.
It may be expected that the higher lignocellulosic content of marsh
plants will reduce the biodegradability of the plants.

ANAEROBIC DIGESTION TECHNOLOGY

Anaerobic digestion of wastewater-grown biomass has two
purposes--helping to stabilize and dispose the biomass and to generate
fuel. These two objectives are, on the whole, compatible. However,
the seasonality and amount of plant biomass produced in some of the
wastewater aquaculture processes, the nature of the plant materials
to be digested, and the high cost of conventional sewage sludge
digesters suggest that alternative digestion processes would be
desirable. Conventional sewage sludge digesters have capital and
operating costs of about $0.015/lb of volatile solids [21]. Assuming
4.5 scf methane/lb of volatile solids, this corresponds to a methane
cost of $3.33/MBTU, or competitive with current or near-term natural
gas costs (currently $2.50/MBTU in California and expected to increase
to $3.50 by late 1980 or early 1981 [22]). This does not include a
cost for the disposal of the sludge or the heating of the digesters.
Large (100,000 ft3) high-rate, masophilic digestion is assumed, yield-
ing about 1 scf biogas/scf digester. The recovery of the biogas for
electricity generation would allow use of waste heat for heating the
digesters. This appears to be the best alternative in most cases.
Another calculation for costs of anaerobic digestion using a con-
ventional stirred tank reactor was recently prepared by SRI Intl.
[23]. For a biogas plant using fresh cattle manure, a cost of $8.50/
MBTU was calculated. However, a large part of the costs were for pre-
and post-processing (e.g. centrifugation of solids) and cost of manure.
The high costs for conventional digestion systems suggest the
need for alternative processes. The aquatic plants would need to be
further concentrated (for microalgae), shredded (for water hyacinths),
or possibly pretreated (marsh plants) to allow use of such digestion
processes. More important, the loadings of standard high-rate sewage
digesters (2-8 g VSS/L/day and up) may not be readily achievable with
aquatic plants, particularly microalgae.
Finally, the expected quantity and its seasonal variability
of the plant material would require a large digester capacity. For
example, for hypothetical design of a 5 MGD microalgal system capable
of secondary treatment and partial tertiary treatment (N removal),
2,500 tons of algal material would be harvested per year versus only

450

1,000 tons of primary sewage sludge [24]. In that design winter
algal production was about two-thirds of summer production, achieved
by assuming higher photosynthetic activities in winter and fewer
operating ponds in summer. This is, however, too optimistic, and it
is doubtful that biomass productivity in the winter months could be
more than 30% of the summer, even assuming cutting down significantly
on growth pond operations in summer. The process of algal flocculation-
sedimentation currently being investigated is likely to exhibit an
even greater variability in productivities [25].
As discussed before, harvesting of water hyacinths could be
spread out to allow a dampening of the strong seasonal variations in
productivity. However, any process depending on nutrient removal by
water hyacinths would produce prodigous amounts of plant material. A
5 MGD system, assuming complete nitrogen removal at 40 mg/L of sewage,
would produce per day about ten times as much digestible solids (about
25 tons/day, assuming 3.3% N of dry weight) than primary sewage sludge.
Thus, a large digester capacity will be required. The unavoidable
differences in summer versus winter harvest will, thus, require at
least a 20-fold increase in capacity, even assuming it is not necessary
to decrease in loading of the digesters. This type of calculation
demonstrates the need for alternative, lower-cost digestion processes
for this biomass. Only a brief descriptive summary of the status of
these alternatives is feasible here.
Two main approaches to lowering the cost of the anaerobic
digestion process have been followed over the past five years, since
the resurgence in interest in biomass energy resources. One approach
was to increase the rate of the reactors by more sophisticated process
control, pretreatment of the feeds, increased mixing or heating, or
improved gas transfer. This type of approach, which is based on the
assumption that process rates will increase faster than costs, is best
exemplified by the two Pfeffer-Dynatech processes which are undergoing
full-scale testing in Florida--the Pompano Beach plant which digests
solid wastes with sewage sludge and the Bartow plant which digests
environmental feedlot wastes [26]. It does not appear, at present,
that these systems provide a significant improvement over conventional
mixed tank reactors. However, economics can still be favorable with
waste treatment and by-product credits. A better approach is that
of two-phase reactors which separate the acid and methane bacteria]
cultures [27,28]. However, it is still uncertain whether such systems
represent a significant enough improvement over conventional two-stage
systems.
The other alternative is exemplified by the gas recovery from
landfills [29], a very slow, unheated, unmixed batch process.
Similarly, gas recovery from anaerobic ponds by use of floating gas
catchers appears to be very promising [30]. Digestion of animal
manures in small-scale plug-flow systems made of plastic material
are the method of choice for low-cost digestion of dairy wastes [31].
As lignocellulosics are not a significant problem with aquatic
plants (except, possibly, for marsh plants), temperature is the
most likely limiting factor in their anaerobic digestion.
Augenstein [32] reviewed the literature and found a reasonably
good fit for data on the rate constant for anaerobic digestion in a
typical Arrhenius plot. Each ten degree increase in temperature

.451

slightly more than doubles the rate of the reaction. However, it is
a common experience that anaerobic digestion below 15'C becomes
extremely slow; thus, that may be considered the lower limit for the
process. The same author also pointed out that mixing is not required
to overcome substrate diffusion limitations in an anaerobic digester.
Thus, simply mixing the influent solids with the microorganisms
(e.g. a part of the effluent stream) should be sufficient for achieving
a good rate of anaerobic digestion. The biggest problem is to avoid
the acid bacteria from overtaking the methane bacteria which results
in "pickeled" or "stuck" digesters. Both buffering with CaCO3 and high
inoculations are suggested. The particular characteristics of waste-
water treatment with aquatic plants--here we have emphasized micro-
algae and water hyacinths--suggest that unconventional digesters such
as designed landfills, covered anaerobic ponds, plug flow reactors,
and other similar alternatives are preferred over conventional sewage
digesters. These processes, however, need further testing and
verification prior to implementation.
Probably the most promising approach to a high-rate anaerobic
digestion process is the "anaerobic filter" process which has recently
been applied to municipal sewage [331. A variant of this process--
the "expanded bed" reactor [31], based on a fluidized bed of small
plastic spheres on which microorganisms attach--is another example
of such an approach. These concepts could have applications to the
digestion of aquatic plant biomass.
Another consideration in anaerobic digestion of aquatic plants
is the disposal of the residual digested sludge. The high-cost al-
ternatives of conventional dewatering or even incineration are not
applicable to wastewater aquaculture systems. Essentially, digested
sludge can be disposed of on land as a source of fertilizer for plant
growth, recycled to the ponds, put on sludge drying beds, or buried in
a landfill. The last option could be combined with the anaerobic
digestion option, particularly for the relatively low-mositure, high-
lignocellulosic marsh plants. Land disposal becomes expensive when
suitable land is not available nearby. The disposal of sludges on
drying beds is a reasonable alternative; marsh plants can play a
useful role in such a process [34].
Finally, digester effluents or the liquid supernatant fraction
could be recycled back to the treatment ponds. This, of course,
must not result in an overload of the system or a large expansion of
it. The relatively large volume of aquaculture wastewater treatment
systems allows the accumulation of considerable amounts of slowly
degradable solids. However, it does not appear that a large increase
in system scale could be justified solely on the basis of the fuel
that could be derived from any additional aquatic plant crop produced.
Thus, digester effluent recycle is only feasible when there is addi-
tional treatment capacity (in summer), nutrients are removed by non-
biological processes (e.g. ammonia volatilization), or no other al-
ternatives are feasible.

ENERGY RESOURCE BASES AND IMPACTS

The fuel that could be derived from wastewater aquaculture is a
very uncertain quantity. Some simplifying assumptions must be made.

452

It will be assumed that two different levels of treatment will be
achieved--secondary (30/30 standards) and tertiary (10/10 standards
plus 40 mg/L nitrogen and 10 mg/L phosphate removal). For secondary
treatment, we shall assume a biomass productivity of 60 MT/HA/yr
and an area of 1.3 hectare per 106 L per day (12 acres/MGD). For
tertiary treatment, we assume a 0.75% phosphorus in the biomass and
a productivity of 80 MT/HA/yr (volatile solids basis) corresponding
to an areal requirement of 6 HA/106 L/day (55 acres/MGD) of growth
ponds (storage ponds will need to be used in winter). It is also assumed
that the digestion process will require no significant amount of the
output fuel (due to waste heat utilization or use of alternative
low-cost energy processes), and that each kg of volatile solid produces
10 ft3 of methane gas. This corresponds to a net 55% conversion
efficiency, assuming 4.5 Kcal/g of biomass. We can then calculate
the fuel produced by the aquatic plant systems as 600 to 800 MBTU/
HA/yr or about 8.0 MBTU/MG treated for secondary standards and 50
MBTU/MG treated for tertiary standards.
It is interesting to compare this fuel output to total energy
inputs in conventional wastewater treatment. Hagan [35] estimates
for a 100 MGD plant 90,000 KW hrs for secondary treatment and 150,000
KW hrs for tertiary treatment stages (with about net 10,000 KW hrs
recoverable from primary treatment). Assuming 10,500 BTU/KW hr
(a 32.5% conversion efficiency to electricity), this corresponds to
9.5 MBTU/MG for secondary and 25 MBTU/MG for secondary plus tertiary
treatment (ignoring primary treatment, which can cover influent
pumping energy requirements). A different source [36] gives 12 MBTU/
MG for secondary treatment and 27.3 MBTU/MG for tertiary treatment
at a 15 MGD scale. For comparison, we must calculate the input energy
requirements in the wastewater aquaculture systems. This input energy
is, unfortunately, far from certain. In the case of high-rate
oxidation pond systems, the energy inputs (including influent pumping)
have been very roughly estimated as about 25% of outputs [37], al-
though they could be considerably lower. An aerated water hyacinth
system, assuming an efficiency of 1.1 kg 02 per KW hr (1.8 lbs 02
per hp hr) [36], with an efficient surface aerator and a 125 mg/L
BOD5 to be met, energy requirements would be 114 KW hrs/106 L or
4.5 MBTU per MG treated (assuming no nitrification). Harvesting and
shredding of the water hyacinths is likely a minor energy input.
Total energy requirements would be at least 60% of outputs. A combined
algal-water hyacinth system would have a much lower overall energy
requirement as would tertiary treatment systems and marsh plant systems.
For a working assumption, the figure of 25% of energy outputs required
for systems operations appears to be useful.
A final consideration is the energy conservation achievable with
wastewater aquaculture systems. It is not quite valid to compare
present conventional technology energy requirements with future
possible aquaculture technologies. Conventional technologies are
rapidly developing energy-efficient processes, and this must be con-
sidered in any comparisons. Also, as land application becomes more
important and "conventional", the relative advantage of wastewater
aquaculture would disappear. Thus, a 15 MGD advanced wastewater
treatment-land application system would consume only 15% of the energy
of conventional processes [37]. Indeed, it would be possible to

453

produce much more biomass fuels with a silviculture wastewater
treatment system than with aquatic plants (due to lower nutrient
and water requirements). It appears that the best combination would
be a combined wastewater aquaculture-land application system [38].
Thus, for calculating energy conservation potentials, only half of
current conventional usage will be assumed.
In the context of this discussion, it is, therefore, reasonable
to assume that a secondary wastewater aquaculture system of 15 MGD
could produce a net fuel output of 6.0 MBTU/MG and an energy con-
servation also of about 6.0 MBTU (50% of present-day activated sludge
requirements). A tertiary treatment system would produce about 37.5
MBTU/MG of net fuel output and have an energy conservation potential
of 13.5 MBTU/MG (again, half of present-day conventional tertiary
treatment).
As 1 MGD corresponds to 10,000 people, total energy production
(net fuel output plus conservation) amounts to 0.44 MBTU/person/yr
for secondary treatment and 1.8 MBTU/person/yr for tertiary treatment.
(This corresponds to roughly 0.1% and 0.4% of per capita energy re-
quirements, respectively). In practical terms, likely energy contri-
butions by wastewater aquaculture systems will fall between these values.
A final consideration is the total energy contribution by waste-
water aquaculture to U.S. energy supplies. A number of limiting factors
must be considered--the need for tertiary treatment, the geographical
and climatic limitations, the capital investments in current technology,
the alternative low-cost wastewater treatment processes, and the
problems of acquiring sufficient land near urban centers. Of a daily
U.S. municipal wastewater flow of about 25,000 MGD by the year 2,000,
it is doubtful that more than 10% could, in the foreseeable future, be
treated by wastewater aquaculture technologies. This estimated market
penetration potential for wastewater aquaculture plants is based on
the data in EPA's 1978 Needs Survey [39]. In 1978 8.2% of the total
U.S. population (219 million) was served by tertiary treatment
systems (701 treatment plants). This will increase to 35.1% of the
population (4,432 treatment plants) by the year 2,000 or 95 million
out of a 270 million population. If treatment more stringent than
secondary is considered, then 9,321 out of 22,768 treatment plants
will require such a level of treatment by the year 2000. However, of
the new plants to be constructed (3,026 plants) which provide treat-
ment more stringent than the secondary, 66% will be smaller than 0.1
MGD and 97% smaller than 5.0 MGD. However, the new advanced treatment
plants above 5 MGD have about 80% of total flows or approximately
2,500 MGD. New construction would be the prime target for new
technologies such as wastewater aquaculture. Enlargement and/or
upgrading of existing plants is of lesser potential for the application
of wastewater aquaculture processes. The total dollars (first quarter
1978) required for such stricter treatment plants is $20.5 billion.
Another view of the potential for wastewater aquaculture technologies
is the number and flows of new required, but not yet funded, treatment
plants which use land treatment, stabilization ponds, or aerated
lagoons which correspond to a total flow of almost 2,000 MGD [39].
Of course, no realistic market penetration analysis is feasible
at present in view of the lack of development of wastewater aquaculture
technology. However, sufficient data exist to indicate that such

454

technologies could be developed in the near term if sufficient R & D
resources are immediately committed, if full-scale demonstration
projects are planned for the early 1980's, and if planning for new
facilities takes into consideration the likely availability of these
novel technologies by the mid-1980's. Under such a scenario a 10%
market penetration for wastewater aquaculture by the year 2000 or
2,500 MGD capacity appears a realistic estimate. Depending on the
level of treatment, this flow would result in a net energy contri-
bution to U.S. supplies of between 0.01 and 0.05 x 1015 BTU, cor-
responding to 0.01 to 0.05% of future U.S. energy supplies (assuming
100 x 10' BTU as total future energy usage. More optimistic assump-
tions are defensible, but still would restrict energy from wastewater
aquaculture to 0.1 x 10's BTU [4]. Thus, it must be concluded that
energy from wastewater aquaculture will be a minor future U.S. energy
source. However, energy from aquatic plant biomass will be an im-
portant component and consideration in the development and imple-
mentation of wastewater aquaculture technology.

455

REFERENCES

1. Duffer, W.R. and J.E. Moyer. Municipal Wastewater Aquaculture, EPA-
600/2-78-110 (June 1978).

2. Benemann, J.R. Biofuels: A Survey. Electric Power Research Institute,
Menlo Park, Calif. (June 1978). EPRI #ER-746-SR.

3. Bethel, J.S. et al. Energy from Wood. Office of Technology Assessment,
U.S. Congress (1979). in press.

4. Benemann, J.R. Energy from Aquaculture. Office of Technology Assess-
ment. U.S. Congress (1979). in press.

S. Murry, M. and J.R. Benemann. "Fresh and Brackish Water Aquatic Plant
Resources." in Handbook of Biosolar Resources II, C.R.C. Press. (1979).
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6. Penfound, W.T. and T.T. Earle. "The Biology of the Water Hyacinth."
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7. Odum, H.T. "Trophic Structure and Productivity of Silver Springs,"
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8. Ryther, J. et al. "Biomass Production by Marine and Freshwater Plants."
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9. Yount, J.L. and R.A. Crossman. "Eutrophication Control by Plant Harvesting."
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10. Boyd, C.E. and E. Scarsbrook. "Influence of Nutrient Additions and
Initial Density of Plants on Production of Water Hyacinths Eichornia
crassipes." Aquatic Bot. 1, 253 (1975).

Boyd, C.E. and E. Scarsbrook. "Accumulation of Dry Matter, Nitrogen, and
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11. Benemann, J.R., B.L. Koopman, J.C. Weissman, D.M. Eisenberg, and R.P.
Goebel. "Development of Microalgae Harvesting and High Rate Pond
Technologies in California." In G. Shelef and C.J. Soeder (editors)
The Production and Use of Micro-Alqae Biomass, Proc. of the Akko Intl.
Symp., Pub. by NCRD (Jerusalem) and GSF (Munchen) (1979).

12. Eisenberg, O.M., W.J. Oswald, J.R. Benemann, R.P. Goebel, and T.T. Tiburzi.
"Methane Fermentation of Microalgae." paper presented at First Intl.
Symposium on Anaerobic Digestion, University College Cardiff, U.K.
(Sept. 18, 1979).

13. Golueke, C.G. et al. "Anaerobic Digestion of Algae." Aool. Microbiol. 5,
47-55 (1957).

14. Golueke, C.G. and W.J. Oswald. "Biological Conversion of Light Energy
to the Chemical Energy of Methane." Appl. Microbiol. 7, 219-227 (1959).

15. Wolverton, B.C. and R.C. McDonald. Compiled Data on the Vascular Aquatic
Plant Proqram 1975-1977. National Aeronautics and Space Administration,
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16. Johnson, A. Final Report on Research in Methane Generation. Aerospace
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17. Lecuyer, R.P. and J.H. Marten. "An Economic Assessment of Fuel Gas from
Water Hyacinths." in Fuels from Biomass, Sewage Urqan Refuse, and
Agricultural Wastes. Instit. of Gas Technology (1976).

18. Chin, K.K. and T.N. Goh. "Bioconversion of Solar Energy Methane Production
through Water Hyacinths." Symp. Papers Energy from Biomass and Wastes,
Instit. of Gas Technology, Chicago, Ill. (1978).

19. Klass, D. Institute of Gas Technology, private communication.

20. Koegel, R. et al. Improvement and Evaluation of Techniques for the
Mechanical Removal and Utilization of Excess Aquatic Vegetation.
Water Resources Center, Univ. of Wisconsin (1978).

21. Environmental Protection Agency. A Guide to the Selection of Cost
Effective Wastewater Treatment Systems, Wash. D.C. (1975).

22. Pacific Gas and Electric, personal communication (June 1979).

23. Jones, J.L. et al. Mission Analysis for the Federal Fuels from Biomass
Program, Vol. V, NTIS TID-29093 (Dec. 1978).

24. Benemann, J.R. et al. Design of the Algal Pond System of the Photosyn-
thesis Energy Factory. Final Report. San. Engr. Res. Lab., Univ. of
Calif., Berkeley. NTIS # HCP/T3548-01 (June 1977).

25. Benemann, J.R. et al. Large-scale Freshwater Microalgal Biomass Production
for Fuel and Fertilizer. Final Report. San. Engr. Res. Lab., Univ. of
Calif., Berkeley. NTIS # SAN 0034-1 (April 1978).

26. Wise, D.L. and R.L. Wentworth (eds.) Fuel Gas Production from Animal and
Agricultural Residue and Biomass. NTIS C00-2991-34 (May 30, 1978).

27. Gosh, S. and D.L. Klass. "Two-Phase Anaerobic Digestion." in Symp. Papers
Clean Fuels from Biomass and Wastes, Instit. of Gas Technology, Chicago,
Ill (1977).

28. Massey, M.L. and F.G. Pohland. "Phase Separation of Anaerobic Stabilization
by Kinetic Controls." J. Water Poll. Cont. Fed. 50:2204 (1978).

29. James, S.J. and C.W. Rhyne. "Methane Production Recovery and Utilization
from Landfills." Symp. Papers Energy from Biomass and Wastes, Inst.
of Gas Tech., Chicago, Ill. (1978).

30. Chittenden, J.A. et al. "Control of Odors from an Anaerobic Lagoon
Treatment Meat Packing Wastes." in Proc. 8th Natl. Symp. Food Pro-
cessing Wastes, E.P.A. (Aug. 1977).

31. Jewell, J.W. et al. Anaerobic Fermentation of Agricultural Residue:
Potential for Imorovement and Implementation, Final Report. Dept. of
Energy (Feb. 1978).

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32. Augenstein, D.C. "Technical Principles of Anaerobic Digestion." un-
published (1978).

33. Pitt, W.W. and R.K. Genung. "Pilot Plant Demonstration of an Anaerobic
Fixed Film Bioreactor for Wastewater Treatment." in D.L. Wise and
R.L. Wentworth (eds.) Fuel Gas Production from Animal and Aqricultural
Residue and Biomass, NTIS C00-2991-34 (May 30, 1978).

34. Seidel, K. "Purification of Water by Means of Higher Plants." Article
translated from Naturwissen Schaften 12, 289-297 (1970).

35. Hagan, R.M. "Energy Requirements in Wastewater Treatment, Part. 2." Water
and Sewage Works 52 (Dec. 1976).

36. Environmental Protection Agency, Energy Conservation in Municioal Waste-
water Treatment. EPA 430/9-77-011 (March 1978).

37. Benemann, J.R. and B.L. Koopman, unpublished.

38. Benemann, J.R., B.L. Koopman, and W.J. Oswald. "A Combined Aquatic-
Terrestrial Wastewater-Biomass System." Proc. of the ASCE Environmental
Engineering Division Specialty Conf., Jack Tar Hotel, San Francisco
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39. Environmental Protection Agency. 1978 Needs Survey,EPA 430/9-79-002.

458

AN OVERVIEW OF THE LEGAL, POLITICAL, AND SOCIAL
IMPLICATIONS OF WASTEWATER TREATMENT THROUGH AQUACULTURE

Loretta C. Lohman
Research Associate
Denver Research Institute
University of Denver
Denver, Colorado 80210

INTRODUCTION

Although technical investigations into the use of aquaculture
for food production have been underway for a number of years, wastewater
treatment by aquaculture is a fairly recent subject of research in this
country even though it was an accepted method in Germany and Russia 40
years ago.1 A review of the literature reveals that only a few of the
ongoing or recently completed studies even briefly touch on legal or
social problems affecting wastewater aquaculture. Since the bulk of
research has been limited to test operations or laboratories, legal,
social, and political implications have been little considered except
in matters involving the human food chain or in addressing legally
defined standards for post-treatment water quality.

This paper, then, is an overview designed to highlight those
legal, political, and social elements which are likely to be common to
any full-scale aquaculture system for wastewater treatment. One such
common element would be that of adequately meeting any federal and state
health, safety, and operating standards, as well as any criteria applied
to the particular treatment process. Other legal, political and social
factors, which neither involve regulatory criteria nor have the benefit
of specific research, can be extrapolated from a review of observed
reaction to water resource management and policy innovation in other
areas, such as reuse. For example, the rigor of specific aquaculture
criteria applied because of its innovative or unfamiliar technology
could lead to diverse political reactions similar to those faced by
land application or groundwater recharge proposals. In turn political
reaction can affect social or public acceptance of innovative wastewater
treatment methods.

Specific examples of legal, political, or social implications
will be drawn from California's experiences for several reasons:

� California has several aquaculture projects in the proposal
or pilot-plant phase;

� Certain elements of the appropriation doctrine are appearing
in the permit systems under creation in riparian states;

* Climatic conditions in California are more suited to aquaculture
than those of many other states;

459

�California is an area of constant innovation in water resource
use and management.

Public attitude shifts, political controversies, and environmental
reactions to water resource proposals have all occurred and been studied
in California. Hence, data from which material applicable to wastewater
aquaculture can be derived are abundantly available and can be analyzed
based upon extensions of previous studies of public responses to water
innovations.

It is also important to note that, because this paper is 'a
judgmental overview of political and social implications, specific names
and incidents will be omitted unless their inclusion is necessary for the
presentation of an accurate picture. The author's intent is to provide a
legal and socio-political outline of areas which will or are likely to be
affected by wastewater aquaculture and which will thus need to be addressed
before any full-scale treatment plants are put into operation.

LEGAL FACTORS

It is the legal responsibilities and obligations of the various
levels and agencies of government--federal, state, local, water allocation,
water quality, and health--that provide the framework in which the politics
and social reactions of groups and individuals take place. Innovative
treatment of wastewater by aquaculture can be governed at each level.

Although the legal implications generally flow downward from
federal to state to region or town, water law, particularly concerning
water quality, displays complex interrelationships with each level
dependent on that above and below. Even so, this paper will attempt
to break the legal discussions into federal and state sections to simplify
the presentation.

Federal Legislation

Wastewater aquaculture will be subject to a veritable "alphabet
soup" of federal statutes, regulations and agencies, including NEPA
(National Environmental Policy Act), NWPCA (National Water Pollution
Control Act) and its 1972 Amendments, NPDES (National Pollution Discharge
Elimination System) permits, EPA (Environmental Protection Agency), the
Safe Drinking Water Act, and possibly FDA (Food and Drug Administration).
Although not exhaustive, this list and the regulations pertinent to it
contain most of the elements of concern to an aquaculture wastewater
treatment proposal.

National Water Pollution Control Act. This act and its 1972
Amendments (Pub. L. 92-500) constitute the most direct control over
wastewater discharges.2 Sections of the act establish stream standards (303),

460

effluent limitations tied to best practicable technology (301), toxic
effluent standards (307), and thermal discharge standards (318), all
of which can determine whether or not aquaculture treatment is the
best technology for a given discharge. The discharges themselves are
controlled by NPDES permits (402), issued either by EPA or its designated
state agency. Specifically aimed at wastewater treatment works, the
permits allow only those effluent discharges which meet federal and
state defined standards. Finally, provisions for areawide waste treat-
ment planning (208) have essentially required that each area of every
state devise a plan to control or reduce all current and future sources
of water pollution including projected uses of energy resources and
energy development. A wastewater aquaculture facility might not meet
the needs of the 208 plan for the area of installation..

The 1977 Amendments to NWPCA (Pub. L.95-217) may constitute
another hazard to wastewater aquaculture facilities. One of its
provisions establishes a priority listing of wastewater treatment
plant projects eligible for funding through the Clean Water Construction
Grant Pro-ram. In interpreting the provision that funding be given to
only those projects which result in compliance with the "enforceable
requirements of this Act," EPA has drawn regulations which will probably
preclude assistance for multipurpose wastewater reclamation projects
unless pollution control is the primary purpose.3 Since, by definition,
aquaculture treatment is multipurpose, federal funding assistance could
be jeopardized under these regulations when tied to the best practicable
technology requirements for wastewater treatment works defined in Pub.
L. 92-500 and in individual NPDES permits.

Safe Drinking Water Act. Since 1962 the U.S. Public Health
Service has maintained drinking water standards. In 1977 the most
recent primary drinking water regulations were given statutory
recognition with the passage of Public Law 93-523. Although the
standards apply to the first step in a water system, they can affect
the last--wastewater treatment--because most treatment plant discharges
enter a watercourse which in turn is a source of drinking water for a
downstream user. Safe drinking water regulations control maximum
allowable levels of contaminants as well as the underground injection
of wastewater. If an aquaculture treatment system does not adequately
remove controlled substances, downstream users or a public health agency
could seek cease and desist orders on any discharges. Such an action
could, in turn, bring a facility into violation of state water rights
laws. If the inadequately treated water is to be used to augment under-
ground supplies, a prohibition against spreading or injection could lead
to serious local water shortages as well as violation of various permits
for operation.

National Environmental Policy Act. This act requires that a
detailed environmental impact statement (EIS) be included in every
recommendation, report, proposal for legislation, or other major federal
action--such as funding a treatment plant--which significantly affects

461

the quality of the human environment. Many states require a similar
statement in areas where the federal requirement does not apply. An
aquaculture wastewater treatment facility will likely be subject to
state or federal EIS's for a number of reasons, including:

* land use is likely to be greater than with mechanical
treatment plants;

*insect production, especially significant mosquito breeding
problems, will be a health factor;

* area residents will be concerned about odor and physical
safety, particularly the attraction ponds present to children:

*water users along watercourses connected to the aquaculture
system will require guarantees that treatment mediums (hyacinth,
duckweed, etc.) will not escape and clog other water works.

Since the time, expense, and frequent legal controversies
surrounding approval of an environmental impact statement often delay
and increase the cost of a project, the Council on Environmental Quality
(CEQ) has promulgated regulations requiring an assessment procedure to
determine if an EIS is needed as well as streamlining and consolidating
the EIS process.4 However, the assessment procedure involves environmental
agencies, project applicant, and the public and thus becomes a political
and social tool in addition to a legal requirement. Any aspect of the
EIS process can then, singly or combined, provide impediments to installation
of a wastewater aquaculture facility.

Food and Drug Administration. The FDA, particularly through the
Delaney Amendment banning any additive found to induce cancer in man,
could play a role in determining the feasibility of wastewater aquaculture
even though the by-products are not intended for use in the human food
chain. For example, by-product application as fertilizer could be severely
controlled if the crop fertilized is used for animal feed for growing
animals to be consumed by humans. Any wastewater aquaculture system will
have to satisfy not only normal waste treatment standards but additional
health--related standards if by-product use in any way relates to, the food
chain. Interestingly enough, thermal was tewater aquaculture will probably
not encounter the same difficulties, as heat and salinity are often the
major pollutants found in such waste.

State Statutes and Regulations

Much of the state law regarding water quality is derived from
federal statutes and standards, particularly those standards relating
to drinking water standards and effluent discharges. However, the states
can and sometimes do set stream standards, discharge requirements, or
water use limitations which are stricter than federal rules. Furthermore,

462

they control the siting, operation and certification of wastewater
treatment plants and the certification of plant operators. States
also have, except in cases of interstate or international compacts,
control over rights to use water and obligations to protect all water
users. This last power can be of particular interest to proponents
of wastewater aquaculture.

Water rights law. In this country, water rights are obtained
under the riparian system or under the appropriation doctrine. The
riparian system gives rights to use of water to the owner of land
abutting a natural watercourse. This system, generally found in the
more humid Eastern states, has in recent years of water scarcity been
modified by most states to include principles of reasonable use, pol-
lution control and a variety of permit procedures limiting the uses
and duration of a water right. The appropriation doctrine is a priority
system, "first in time, first in right," which establishes rights to use
water on the basis of the date of appropriation, modified by beneficial
use and use preference standards. Under both systems, more state controls
are developing in the face of population growth, water scarcity, and the
strains of increasing pollution. In either system it is likely that
a state has or will obtain enough control over water to protect all
water users from diminishment of water quantity or quality. However,
because the author is more familiar with Western appropriation, specific
problems pertinent to wastewater aquaculture will be addressed under that
doctrine.

Specifically, wastewater aquaculture may damage the rights of
downstream water users to either a specific quantity or quality of
water. The situation is similar to that encountered in land application
wastewater treatments wherein downstream users have been deprived of an
amount of water--effluent--which has made up a portion of their water
right. There has even been at lea~st one case where downstream users have
sued for their right to dirty water because they had come to rely on the
nutrients it contained. Diminishment of quantity could occur when the
aquaculture process is wetlands treatment; or if the process doesn't meet
discharge standards; diminishment of the expected quality could occur
if the aquaculture works either too well or not well enough. In either
case, affected users could sue for damages covering a number of years
or obtain cease and desist orders. In California, and any other state
with anti-paralleling statutes, operating income from the sale of the
treated water could be in competition with fresh water purveyors and
thus be restrained even though ownership of such water is usually the
plant's until it enters a watercourse.

The questions of water ownership and historic patterns of water
flow are extremely complex and vary somewhat in every state. However,
any innovative use or treatment of water could impact on historic patterns
or on other users and therefore must be addressed when considering an
aquaculture treatment facility. The preservation of the watercourse from
the treatment medium will be among such concerns.

463

Public health. Although all states have water quality laws
and regulations, previously described federal requirements cover similar
concerns. It is the public health aspects of aquaculture, particularly
as exercised in discharge permits, that will most affect any facility.
Not only do states exercise direct control over wastewater treatment
facilities--plans, construction, operation, maintenance, and operator
certification--but most of them also exercise direct authority over
or have major influence on the issuance of NPDES permits. Items which
a permit will address are likely to include:

* identification of any diseases or parasites resulting from
the project which could affect aquatic life outside the project;

* identification of the plants or animals to be used in the
treatment;

* potential for escape of the treatment medium from the project
area;

* concentrations in treated water of pollutants to be controlled;

* uses of the process by-products;

* concentrations of carcinogens or mutagens in the by-product;

� reliability of the system;

*identification of emergency procedures to handle surges of
toxic materials;

* operator training requirements.

Naturally, the initial state concerns will focus on whether or not the
process will meet the defined standards for secondary or tertiary treatment.
That first must be proven.

Guarantees against the escape of treatment medium can fall under
health, water rights, or political concerns depending on the plafits or
animals and the geographic area in which such plants and animals are
used. This factor, combined with the need to protect public health,
could determine what types of plants and animals may be used in any
particular aquaculture facility.

Uses of by-products will likely be controlled in the permit
at the state level since the food chain is not likely to be involved
in the near term. This permit will involve regulation of any direct
use or application of the treated water as well. For instance, pasture
irrigation may only be permitted up to three days prior to its use to
allow solar and wind sterilization of the fodder.

464

System reliability, emergency procedures and operator training
will be determined through state waste treatment regulations. These
will have to be expanded to include the innovative techniques of aqua-
culture and may include requirements as to biological training, or
the like.

Each of these factors will probably be handled at a state level
or with a large degree of state input to the NPDES process.

Although it is not possible to present an inclusive listing
of potential legal problems, one other which is reflected at a state
and local level, and may be included in the permitting process, is
worthy of note. That is the possibility that the ponds or marsh
areas necessary to aquaculture could serve as an insect breeding
ground, particularly for mosquitoes, would demand attention. This
is not only a potential health hazard but could be classified as a
public nuisance and dealt with as such.

POLITICAL ELEMENTS

The legal framework not only defines the obligations and regulations
of water use, water quality, and public health and safety, but it also
creates the forum in which political activity takes place. Thus it
can be difficult to separate the legal from the political because of
the ubiquitous nature of politics. Indeed, any reviewer of water manage-
ment literature will have noted that most legal-institutional studies are
unable to separate the two, with a resulting presentation of the material
in essentially legal terms. In an effort to clarify the meaning of political
factors to be discussed, this paper first defines institution as the
actual operating activities, as shaped by administrative policy and
precedent, of a person or agency charged with application of the legally
defined processes germane to wastewater aquaculture. These institutions
are the political arena directly pertinent to establishment of a facility.
This definition directs the focus to the agencies and actors most concerned
with the activities involved in the planning, construction, funding,.
operation, maintenance, and permitting of wastewater treatment plants.
Public reaction, including political response, is addressed only as one
of the influences on the institutional players.

Patterns of influence. No agency or administrator works in a
vacuum. Each agency or administrator, in addition to specific legal
responsibility, is part of a larger governmental entity with broader
and even different purposes and goals. Such factors influence an
agency's or administrator'~s approach to the direct responsibilities
at hand. In proposing a wastewater aquaculture facility, an agency
or administrator might be subject to such influences as:

a national water policy emphasizing conservation and innovative
water treatments;

465

� EPA interpretations which could jeopardize funding of multi-
purpose projects;

* requirements to meet safety standards which are not fully
defined;4

* state agency desires to maximize water use;

* federal or state standards on effluei~t discharges;

� area land use or growth policies;

* compact commitments to deliver water to another entity;

� policies favoring one type of treatment over another;

* public concerns for environmental and safety factors;

* interagency disagreements on practicality or feasibility.

The pattern which emerges is interrelated, complex, and somewhat confused.
National executive policy, which should be carried out by EPA, is instead
susceptible to narrow interpretation, as in rules for funding multipurpose
projects. State policy, based an water law and historic uses of water,
may preclude some types of treatment (such as wetlands) and may conflict
with national policy. Within the statest, agencies with different legally
defined missions may hinder each other or local initiatives. Land use
and growth policies may conflict with water treatment proposals, and the
like, as policies and agencies bounce against each other and create demands
upon a project proposal.

Efforts to establish aquaculture facilities in California can
illustrate many of these elements. It is state policy to optimize water
use through conservation, treatment and recycling. However, reuses such
as groundwater replenishment and food chain irrigation have often been
hindered by the state health department, and aquaculture plants have yet
to receive discharge permits. In addition, federal funding under the
Clean Water Construction Grant Program is in question for the types of
multipurpose projects considered in California. Finally, some marshland
maintenance with reclaimed water is under attack by local mosquito
abatement districts.

Chemehuevi Wastewat~er Reclamation Facility. One of the most
graphic examples of the conflicts facing wastewater aquaculture can
be found in the efforts of the Chemehuevi Indian Tribe to build a facility
on their reservation near Lake Havasu, California. The plant was to be
funded by a grant from the Economic Development Administration (EDA), U.S.
Department of Commerce. It was to treat raw domestic sewage to better
than secondary standards by means of an aquaculture system using water
hyacinth plants and teleost fish. Effluent was to be used to irrigate

466

reservation crops or to be evaporated in the desert. By-products were
,to be harvested and used for an unspecified purpose, possibly for sale.5
The California State Office of Economic Opportunity strongly supported
the project, with endorsements from the Bureau of Indian Affairs and
the federal Office of Economic Opportunity.

Early reaction to the proposal was addressed to the California
Water Resources Control Board, the Colorado River Basin Regional Water
Quality Control Board, and Region 3 of the U.S. Bureau of Reclamation.
The Colorado River Basin Regional Water Quality Control Board acted as
the lead agency in discussing comments and negotiating with the parties.

Comments objecting to the use of water hyacinths were received
from the Imperial Dam Advisory Board, the Coachella Valley County Water
District, Imperial Irrigation District, Wellton-Mohawk Irrigation and
Drainage District, and the Metropolitan Water District of Southern
California. The Colorado River Board of California participated in
the discussion and kept informed on the negotiations.6 The major
fear was that water hyacinths could be accidentally introduced into
the Colorado River system, would then interfere with pumping operations
and clog watercourses.

Under such circumstances the National Environmental Policy Act
required an environmental assessment and possibly an Environmental
Imp-act Statement before the grant could be made. Because of the degree
of opposition generated by the proposed use of water hyacinths, the
Chemehuevi Tribe switched to use of indigenous duck-weed and obtained
a negative determination as to the need for an EIS.

This negotiated settlement carried four EDA conditions: (1) the
Tribe had to notify local entities of a-ay change from duckweed as the
treatment plant; (2) EPA, Bureau of Reclamation, and the Forest and
Wildlife Service would form an advisory group to evaluate the impact
of any change in treatment plants; (3) approval from appropriate health
agencies would have to be obtained before the sale of fish or other food
products; and (4) certain design standards would have to be met at the
pumping station.7 Unfortunately, those conditions could not be enforced
as neither a state agency nor EPA had jurisdiction over what could be
considered an "independent Indian nation." The only recourse would have
been a civil suit by a damaged party after damage had occurred.

Because of the concerns of local and federal agencies responsible
for water use and quality, the EDA grant funds were delayed and the Tribe
cancelled their aquaculture plans in favor of a conventional wastewater
treatment plant. In part, this occurred because the Tribe, although
dependent on government aid, was not subject to normal rules and could
not receive needed state aid for construction of collection facilities
without surrendering some autonomy and submitting to some state jurisdiction.
Furthermore, the questions of adequately meeting safety standards, ob-
taining discharge permits, and receiving permission to sell by-products
loomed as future problems which could have created more opposition to the
project.

.467

The Chemehuevi proposal illustrates the conflicting policies of
state and federal agencies as combined with vested interests of agricultural
groups, water districts, and Indian improvement proposals. While no one
wished to deny the Tribe's right to advance, the implications of the
method caused a number of serious political obstacles.

Role of agency/administrator. All of these previously discussed
factors come to bear on the actors who are on the line, the people who
make up the agencies related to wastewater treatment, public health and
water management, and who must take the daily actions necessary to
administer the varied elements of these programs. Depending on agency
mission these actors are subject to a variety of clientele seeking to
preserve or advance a particular interest. It is essentially these
agency personnel, and the way they perceive their roles, who shape
legal obligations into a particular administrative process. Their
role identification performs a dual function: it guides the develop-
ment of policy which guides administration of legally defined duties;
and it defines the type of relationships that are established between
the agencies.

For example, an administrator's distrust of aquaculture treatment
processes could extend to his agency procedures--making necessary permits
or regulations more difficult to obtain or follow. In another way,
traditional agency rivalry or interpersonal mistrust could hinder
acceptance of a proposal. Agencies are generally accustomed to responding
in a traditional manner to familiar request from an accustomed clientele.
Insertion of an innovative process requiring unusual types of administrative
action involving differing agencies can exacerbate underlying tensions or
introduce new ones.

Because of the myriad of agencies, administrators and vested
interests who might be involved in a specific aquaculture project it
is difficult to construct a "typical" political scenario. For instance,
in Hercules, California, the city government opted for a wastewater
aquaculture facility because the regional council of governments
blocked funding for a traditional facility. Hercules was not scheduled
for growth according to regional plans. Because the Hercules' govern-
ment has chosen to grow and must therefore have additional treatment
facilities, the aquaculture facility was chosen because it is less
expensive and is entirely city financed.8 This scenario places a
unified city government in opposition to regional, state and federal
agencies. At this point, state health officials have issued the necessary
discharge permits for complete operations with a requirement for four times
the frequency of normal testing. Even so, because it was a city decision--
"us against them"--little interagency rivalry had opportunity to emerge.

Such rivalry was beginning to emerge in the Chemehuevi project and,
as more wastewater aquaculture facilities are proposed (especially wetlands
processes), vested interests for traditional patterns of water use and
treatment could come more into conflict with those agencies charged to
seek out innovative procedures.

468

SOCIAL IMPLICATIONS

As the political elements spring from the legal factors, so
the social implications of wastewater aquaculture spill out from the
political. Interagency dispute over a project, professional distrust
of the procedure, or an attitude similar to Hercules' "us vs. them,"
can all contribute to public attitudes and responses. The presentation
of information and interpretation of scientific data, along with the
method of citizen participation in a proposal, also influence and
direct public response.

All in all, societal positions relating to wastewater aquaculture
treatment can be expected to encompass a broad range of individual and
group concerns about water supply and water quality. Such affected parties
include not only the average citizen and the downstream water user but
also organized interest groups--farmers, Chambers of Commerce, labor
unions seeking more jobs, homeowners, and municipalities. It is the
water or health administrator's perception of these societal positions
which is ultimately reflected in many of his actions.

General attitudes. It has been assumed, but never specifically
demonstrated that wastewater aquaculture would encounter problems of
public acceptance; many of the social impacts encountered in water reuse
projects can be expected to be associated with proposed aquaculture
projects. A discussion of reuse attitudes can be helpful in under-
standing public concerns about and responses to innovative water use
proposals. It should be noted, however, that an interviewee's failure
to express disgust at a proposal cannot be taken as implicit approval.
The one study which attempted to derive aquaculture attitudes from water
reuse surveys made this error.9 The fact that 56.4 percent of respondents
oppose drinking reclaimed water does not mean that 43.6 percent are in
favor of it or would, by the study's extension, serve as a market for
food grown in wastewater. To infer such is .a careless manipulation of
data.

A review of the literature does suggest that the general public
is more flexible in attitude toward water innovations than is the professional
water manager or health agent.10 This might be due in part to the public's
lack of complete information about specific factors such as toxic contami-
nants, but it is also the result of long-term acceptance of and belief in
water-system reliability and safety. Along with proper presentation of a
wastewater aquaculture proposal this attitude will probably aid acceptance.

Several droughts and water supply problems that have occurred
throughout the nation in recent years have created a broad public awareness
of water problems and a willingness to adapt expectations to meet them.
One public response to these problems has been a willingness to accept
innovative uses of water. Reuse as a general concept has had wide
public acceptance once health and safety factors, and the protection of

469

existing water users have been adequately addressed. Such a response
is likely for wastewater aquaculture which does not form part of the
human food chain.

In Denver, an 84.1 percent approval was given to potable reuse
of wastewater if the resulting water quality were the same as that
currently supplied to each home.11 Despite some difficulties in
transferring the results of this survey, a reasonable extrapolation
from these data could find as many as 70 percent willing to use aquaculture
products in the food chain if their quality was the same as that presently
obtainable elsewhere.

The only aquaculture project nearing operation is in Hercules,
California. Citizens in that city, in a series of public meetings, were
impressed by the energy conservation aspects and possible by-product
uses for mulch and commercial fertilizer.12 No organized opposition
surfaced, probably because disposal has been, and will temporarily be
deep-water outfall and not part of another's water supply. Such easy
acceptance will not continue if effluent fails to meet health standards,
or if odor or insect growth cause any area nuisances.

Nor will wastewater aquaculture meet so little opposition in
areas where effluent makes up part of downstream water supplies, where
other treatment alternatives are readily available, or where a less
rigid political situation exists. Like reuse, wastewater aquaculture
will be most acceptable where risk of body contact or ingestion is
remote and nuisance variables, such as excess mosquito production,
are kept under control.

Environmental concerns. Preservation of water quality and
the amenities of natural stream flow--vegetation, wildlife, recreation--
are at the root of environmental concerns with water management. In
essence, wastewater aquaculture by wetlands processes would be generally
acceptable environmental goals. However, aesthetically displeasing water,
in which the odor, taste or appearance is bad, could raise environmental
concerns. The uses of land in an urban area can also attract environmental
interest. Aquaculture is generally more land consumptive than conventional
treatment methods and could still create odor, appearance, or related growth
problems. Control of plant environs will be necessary to satisfy aesthetic
as well as health concerns.

Demographics. The expected public response to a wastewater
aquaculture project, as well as the kinds of environmental concerns
expressed, will depend in large measure on the makeup of the population
affected. In a populace with a tradition of citizen involvement, managerial
unease about aquaculture could be reflected in public reluctance to
innovate in an area as sensitive as wastewater treatment and food
production. An understanding of the involved population is of particular
importance. For example, some of the "sun-belt" locations most available
for wastewater aquaculture treatment might have a disproportionately older

470

or more politically conservative population (such as Palm Springs,
California, or Miami Beach, Florida) which could be less receptive to
innovation, particularly in water treatment or use.

Other factors which, in combination with age or political posi-
tion, will play a role in social acceptance or rejection of wastewater
aquaculture include education level, income, type of work, and citizen
involvement. An honest, but carefully designed, education and informa-
tion program will reflect these factors and address those issues which
most concern the affected population.

CONCLUSIONS

As in any area affecting the uses and quality of water,
wastewater aquaculture faces legal, political and social complexities
of great scope. The truism that sufficient funding can overcome just
about any water problem is only partially true in this instance.

Certainly sufficient monies will diminish any water rights
problems if damages could be paid or rights purchased. However,
water quality is dependent on the state-of-the-art technology. Money
alone is not sufficient to clean water if the technology used is
inadequate. If aquaculture technology cannot adequately meet health
and safety standards some other form of treatment w~ill have to ensue.

Lead agency. One of the ways to deal with the legal demands
and resulting political conflicts which could face a was tewater
aquaculture proposal would be the establishment of a lead agency to
coordinate planning, public information, and legal requirements. Such
an agency could address the specific concerns of involved federal and
state agencies from a single information source. Political issues,
such as those which might result from the EIS process, could be
handled in a consistent manner and, at the same time, be examined or
included in the proposal. In Hercules, the city council served as a
lead agency, while the Chemehuevi project suffered because response
and authority was apportioned between the Tribe, EDA, and the California
State Office of Economic Opportunity.

Incentives. Although the national water policy presents a call
for innovative methods of water use and treatment, EPA interpretations
of funding regulations cast doubt on the feasibility of funding innovative
multipurpose facilities. Thus the only real incentive, at present, is
the lower construction and operating costs of a wastewater aquaculture
facility. These savings could be offset by discharge restrictions, extra
testing requirements, or limitations on by-product use. Until the
incentive to innovate is clear, outweighing extra demands for
educational and environmental safeguards, was tewater aquaculture will
not receive wide consideration.

471

Citizen participation. The legal requirements upon wastewater
aquaculture have to be dealt with in a legally prescribed manner.
However, many of the social and political implications of such a
project can be addressed through a properly designed citizen participation
program. As was noted earlier, the public is sometimes ahead of the
professionals in willingness to innovate. A good program could allow
them to lead rather than react.

Hercules' program, because it is a small town, was simply a
series of public meetings for the exchange of views. Different circum-
stances might require more formal programs. The EUS procedure prescribes
a public participation formula which could be adapted; round-table
sessions could be scheduled; newspaper debates could be instituted;
attitude surveys could be conducted and discussed. In short, there
are myriad ways of developing public participation which could be
adapted to a particular community. Only one rule is unchangeable--
all official presentations must be completely honest.13

ACKNOWLEDGEMENTS

The author wishes to thank the many students of aquaculture
who took time to discuss various ideas with her. J. Gordon Milliken
and Professor Terence. J. Lohman contributed editorial review and stylistic
guidance.

472

FOOTNOTES

1. Steel, Ernest W., Water Supply and Sewerage, New York: McGraw-Hill
Book Company, Inc, 1947, pp. 490-491.

2. See: MacArthur, Gregory, Some Ecological Implications of the 1972
Amendments to the Federal Water Pollution Control Act, Denver:
Rocky Mountain Center on Environment, September 17, 1973; and,
A Legislative History of the Water Pollution Control Act Amendments
of 1972: Vol. I and II, Washington, D.C.: Congressional Research
Service, 1973.

3. California State Water Resources Control Board, Office of Water
Recycling, "Background Information Regarding Funding of Water
Reclamation by U.S. Environmental Protection Agency," April 17, 1979.

4. Council on Environmental Quality--National Environmental Policy
Act, "Implementation of Procedural Provisions; Final Regulations,"
43:230 Federal Register, part IV, Wednesday, November 29, 1978,
pp. 55977-56007.

5. Description, Attachment to WRCB Form 200 (2-72) Rev. 6, November
10, 1976; and Solar Aqua Systems, Inc. Process description.

6. Colorado River Board of California, memorandum, July 18, 1977.

7. Metropolitan Water District of Southern California, memorandum,
October 31, 1977.

8. Dorway-Worley, Pam, "Hercules City Council Was Faced with a Critical
Decision," Compost Science/Land Utilization, May/June 1979, p. 19.

9. Kildow, Judith and John E. Huguenin, Problems and Potentials of
Recycling Wastes for Aquaculture, Cambridge, Massachusetts:
Massachusetts Institute of Technology, December 30, 1974, pp. 96-97.

10. See: Nieman, Thomas J., "Water Reuse and the Professionals," in
Water Reuse and the Cities, Roger E. and Jeanne X. Kasperson,-eds.
Hanover, N.H.: The University Press of New England, 1977, pp. 143-165.

11. Carley, Robert Lane, Wastewater Reuse and Public Opinion, Master's
Thesis, University of Colorado, Department of Civil and Environmental
Engineering, 1972.

12. Personal conversations with Pam Dorway-Worley, August 1979.

13. See: Chatland, Harold, A Technique to Assist Citizen Groups in
Decision Making, National Science Foundation, n.d.,; and Institute
for Participatory Planning, Citizen Participation Handbook for
Public Officials and Other Professiocials Serving the Public,
Laramie, Wyoming: IPP, 1978.

473

The reader may also wish to consult:

In the study of public attitudes, William H. Bruvold, of the
School of Public Health, University of California at Berkeley, has
conducted a series of public attitude surveys on the reuse of water:
"Public Attitudes Toward Uses of Reclaimed Wastewater," Water and
Sewage Works, April 1970, pp. 120-122; Public Attitudes Toward Reuse
of Reclaimed Water [n.p.], University of California, Water Resources
Center (Contribution No. 137), August 1972; and "Using Reclaimed
Water: Public Attitudes and Governmental Policy," Public Affairs
Report, 17:3, June 1976, Bulletin of the Institute of Governmental
Studies, University of California, Berkeley. Other surveys include:
John Sims and Duane Baumann, "Renovated Waste Water: The Question of
Public Acceptance," and Duane Baumann, "Public Acceptance of.Renovated
Wastewater--Myth and Reality," Water Resources Research, 10:4, August
1974, pp. 659-665, and pp. 667-674 respectively; and Ralph Stone and
Company, Inc., Wastewater Reclamation: Socio-Economics, Technology,
and Public Acceptance, Los Angeles: 1974, Chapters II-V.

Some interesting political patterns are examined in:

Helen M. Ingram, Patterns of Politics in Water Resource Development:
A Case Study of New Mexico's Role in the Colorado River Basin Bill,
Albuquerque: University of New Mexico, Institute for Social Research
and Development, Decmeber 1969; and Dean E. Mann, Water Policy and
Decision-Making in the Colorado River Basin [n.p.], Lake Powell
Research Project Bulletin No. 24, July 1976.

474

ECONOMICS OF AQUATIC TREATMENT SYSTEMS

Ronald W. Crites, Project Manager, Metcalf & Eddy,
Sacramento, California 95814

Aquatic treatment systems use various aquatic plants and animals to
achieve wastewater treatment. System types include those using
artificial wetlands, macrophytes (principally water hyacinths),
invertebrates, fish, and integrated (polyculture) combinations of plants
and animals. These systems, like land treatment systems, are
alternatives to conventional mechanical facilities that use a great deal
more resources (chemicals) to treat wastewater. This paper explores the
economics of these aquatic systems and compares their costs with those
of land treatment and conventional treatment. Design conditions and
land costs will be varied to ascertain the importance of these
parameters in overall costs.

DESIGN CRITERIA

The criteria that principally affect capital costs in aquatic
systems are hydraul ic detention time and depth of water in the pond or
wetlands. Reported values of these parameters and resultant area
requirements are presented in Table 1. The reported range is very wide
because it includes some combinations of oxidation ponds with the
aquatic treatment systems. The values listed in Column 2 are typical of
the recent literature on artificial wetlands [1], water hyacinths �2],
and polyculture [3, 4], and will be used later in this paper for the
cost comparisons. There are too few experimental systems using fin fish
to allow specific design criteria to be set.

475

Table 1. DESIGN CRITERIA FOR AQUATIC TREATMENT SYSTEMS

Type of system Reported range Values used

Artificial wetlands
Detention time, days 2-25 10, 20
Depth, ft 0.5-3 1.5
Area, acres/mgd 10-130 20, 40
Water hyacinths
Detention time, days 4-60 5. 10
Depth, ft 1.5-5 3
Area, acres/mgd 2-40 5, 10
Fin fish ponds
Detention time, days 5-60 --
Depth, ft 2-10 --
Area, acres/mgd 3-40 --
Polyculture
Detention time, days 4-15 10
Depth, ft 4-10 6
Area, acres/mgd 1.5-7.5 5

Artificial Wetlands

Artificial wetlands are distinguished from natural wetlands because
of the capital cost of constructing a shallow pond or marsh. Small
reported on a constructed marsh-pond system for treatment of various
wastewaters and recommended 12 to 15 days of detention time for treating
raw wastewater [1]. De Jong reported 96% removal of BOD at detention
times of 10 to 16 days in wetlands containing rushes and reeds [5].
Kadlec indicated that the detention time for natural wetlands may
be considerably longer than for artificial wetlands and that the natural
systems may have area requirements of about 50 acres/mgd [6]. The
natural wetlands projects usually function year-round in areas as far
north as Wisconsin, Michigan, and Minnesota.

Water Hyacinths

Several researchers have reported on the use of water hyacinths for
wastewater treatment including Wolverton [2], Dinges [7, 8], and
Cornwell [9]. Systems designed for secondary treatment typically have
detention times of 5 to 10 days and depths of 3 to 4 feet.
The area requirements for hyacinth ponds can increase if winter
storage is required. Most projects to date have been located in
Florida, Mississippi, and Texas. Water hyacinths cease to grow when
water temperature is about 400C or below 100C, and hyacinths are killed
when the tip of the rhizome becomes frozen [10]. Consequently, winter
storage or alternative macrophytes are necessary where winter water
temperatures drop below 10�C.

476

Another factor affecting the cost of hyacinth systems is harvesting
and use or disposal. For systems designed for secondary treatment, it
is assumed that harvesting will be limited annually to 10 dry tons/acre.
This practice seems necessary to maintain some open water in the pond
and to keep the hyacinths growing. Higher harvesting rates in Florida
are designed to remove the nutrients contained in the hyacinths [11].
Another aspect of possible economic interest is the ability of
water hyacinths to transpire water at a rate higher than lake
evaporation. This phenomenon has been measured at between 1.5 and 3
times lake evaporation [12, 13]. Where the effluent level of TDS or
salinity is of concern, other plants such as duckweed could be
considered or the potential for covering the system could be
investigated.

Fin Fish

Stowell et al. listed blackfish, carp, tilapia, catfish, mosquito
fish, and white amur as fin fish that could be used in wastewater
aquaculture [14]. Coleman et al. reported on an experimental system at
Quail Creek in which channel catfish, golden shiners, and tilapia were
introduced [15]. Despite predation of the golden shiners by black
bullhead already present in the lagoon, the system reduced the suspended
solids effluent concentration to 12 mg/L. Detention time in the six-
cell pond system totalled 70 days with half of the ponds containing
fish.

Polycul ture

Although most aquatic treatment systems could be called
polyculture, this term is applied here to integrated, planned systems
involving plants, fish, bivalves, or crustaceans. Dinges tested a 5-
step polyculture system with a detention time of 5 days [3]. The ponds
varied in depth from 2 to 8 feet, but the treatment performance was
quite high, as shown in Table 2.

Table 2. PERFORMANCE OF A FIVE-STEP POLYCULTURE
SYSTEM OVER FIVE MONTHS [3]

Wastewater constituent Influent, mg/L Effluent, mg/L Reduction, %

BOD20, mg/L 90 18 76
TSS, mg/L 35 7 80
Organic nitrogen, mg/L 4.8 1.2 75
Ammonia, mg/L 2.1 0.1 95
Fecal coliforms, No.1100 mL 1,400 10 99

477

COST OF AQUATIC SYSTEMS

Very little information on costs is available in the literature.
In 1976, Henderson and Wert compared 15 strategies involving
conventional and aquatic treatment systems [16]. At a flow of 0.2 mgd,
the cost-effective strategy for secondary treatment was the addition of
an aquatic treatment system to an oxidation pond. No strategies were
found to reduce nitrogen below 3 mg/L. They also found that the
economic return from aquaculture products was not critical to their cost
effectiveness.

Basis of Costs

Costs of water hyacinth treatment, artificial wetlands, and
polyculture, in conjunction with oxidation ponds and land treatment, are
compared based on March 1978 costs. The basis of the conventional and
land treatment costs is presented in Crites et al. [17]. The major
elements are summarized in Table 3.

Table 3. BASIS OF COST COMPARISONS

EPA STP index 290.1
Date of comparison March 1978
ENR CC index 2693
Power cost, �/kWh 4.6
Labor, $/hr 8.35
EPA O&M index 1.67

Land Costs

Land costs were included at $4,000/acre and at $10,000/acre. Land
appreciates at 3% per year according to the EPA cost-effectiveness
guidelines. The area requirements for the treatment systems are
summarized in Table 4. The multiple listings of areas represent two
different conditions.

Table 4. LAND REQUIREMENTS

System Area, acres/mgd

Conventional, aerated lagoons, and AWT 1
Oxidation ponds 18, 30
Hyacinth ponds 5, 10
Artificial wetlands 20, 40
Polyculture 5
Rapid infiltration 20
Overland flow 60
Slow rate 160

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Advanced Secondary Treatment

Costs of 1-mgd advanced secondary treatment systems were estimated
using data from the EPA updated report on Costs of Wastewater Treatment
by Land Application [18] and from Crites et al. [17]. Advanced
secondary treatment is defined as BOD and suspended solids of 10 mg/L
and fecal coliforms of 200 MPN/lO0 mL.

Water Hyacinth Ponds. A treatment system consisting of preliminary
screening and grit removal, oxidation ponds, and water hyacinth ponds
was evaluated under two different conditions. These conditions are
described in Table 5. The climate must be moderate to allow water
hyacinths to survive in the winter. The harvested hyacinths are assumed
to be composted and sold or given away. The costs of advanced secondary
treatment using the conditions in Table 5 are presented in Table 6. As
indicated in the table, the less favorable conditions nearly double the
treatment costs and the principal effect is in the capital costs. The
cost of the land increases from 3% of the total cost to 7% under the
less favorable conditions. Harvesting costs at $10 to $20 per dry ton
have a negligible effect on overall costs.

Table 5. CONDITIONS FOR A 1-mgd ADVANCED
SECONDARY SYSTEM USING WATER HYACINTHS

Conditions
Factor Favorable Less favorable

Oxidation pond area, acresa 18 30
Hyacinth pond area, acres 5 10
Wastewater pumping head, ft 150 150
Piping to site, miles 1.5 5
Land cost, $/acre 4,000 10,000
Harvesting cost, $/acre 100 200
Return on compost, $/acre 50 0

a. Based on 5-ft deep ponds with detention times of
30 days for favorable conditions and 50 days for
less favorable conditions.

Table 6. COSTS OF A 1-mgd ADVANCED SECONDARY SYSTEM
USING WATER HYACINTHS

Conditions
Favorable Less favorable

Capital cost, $/gal of capacity 1.15 2.21
Capital cost (amortized), �/1,000 gal 26.6 46.4
o&M cost, �/1,000 gal 16.9 22.5
Land cost, �/1,000 gal 1.2 5.3
Total cost, �/1,000 gal 44.7 74.2

479

Artificial Wetlands. A flowsheet similar to the one for water
hyacinths was also evaluated. This flowsheet contained an artificial
wetlands following the oxidation ponds with favorable and less favorable
conditions described in Table 7. The climate is not restricted to
moderate and no return was assumed for the harvested plants. The costs
of a 1-mgd system are presented in Table 8.

Table 7. CONDITIONS FOR A 1-mgd ADVANCED SECONDARY
SYSTEM USING ARTIFICIAL WETLANDS

Conditions
Favorable Less favorable

Oxidation pond area, acres 18 30
Wetlands area, acres 20 40
Piping to site, miles 1.5 5
Land cost, $/acre 4,000 10,000
Harvesting cost, $/acre 50 200

Table 8. COSTS OF A 1-mgd ADVANCED SECONDARY SYSTEM
USING ARTIFICIAL WETLANDS

Conditions
Favorable Less favorable

Capital cost, $/gal of capacity 1.23 2.66
Capital cost (amortized), t/1,000 gal 28.6 50.3
O&M cost, �/1,000 gal 19.6 29.8
Land cost, �/1,000 gal 1.5 9.4
Total cost, $/1,000 gal 49.7 89.5

The costs for advanced secondary treatment using oxidation ponds
followed by artificial wetlands are slightly higher than for the
previous flowsheet using water hyacinths. At $10,000/acre, the cost of
the land needed for the wetlands and ponds, 70 acres/mgd, becomes 19% of
the capital cost and 11% of the overall cost.

Comparison with Land and Conventional Treatment. The two
flowsheets using aquatic treatment processes were then compared with
conventional treatment and land treatment using overland flow. The
conventional treatment consists of activated sludge followed by dual
media filtration. The costs for a 1-mgd system are compared in Table 9.
For favorable conditions, the hyacinth treatment is 35% of conventional

480

and for less favorable conditions it is 57% of conventional treatment.
Keeping all other conditions (in the less favorable column) constant,
the price of land could be $115,000/acre before the conventional system
would be equal in cost to the oxidation pond plus water hyacinth system.

Table 9. COST COMPARISON OF l-mgd ADVANCED SECONDARY SYSTEMS
0/1,000 gal

Conditions
Treatment system Favorable Less favorable

Oxidation pond plus hyacinths 130 74
Oxidation pond plus wetlands 50 90
Overland flow 96 115
Conventional 130 130

Advanced Wastewater Treatment

Two flowsheets were developed to meet advanced wastewater treatment
(AWT) standards using land and aquatic treatment processes. AWT is
defined in this case to be advanced secondary plus nutrient removal.
The effluent requirements are total nitrogen less than 3 mg/L and total
phosphorus less than 1 mg/L. These standards exist only in a few areas
of the United States and may not be applied-widely. It is important to
compare costs of achieving these standards by various means, however,
and to compare nutrient removal costs with those of advanced secondary
treatment.

Polyculture Plus Rapid Infiltration. A promising flowsheet for AWT
consists of preliminary screening and grit removal, oxidation ponds,
polyculture (without aeration), and rapid infiltration. The assumptions
for oxidation ponds, land, and piping to the site are the same as for
the favorable conditions under advanced secondary treatment. For
polyculture, a multiple-cell, 10-day detention time system patterned
after Dinges [3] was developed. The average depth is 6 feet and the
area needed is 5 acres. No aeration or pond covering is provided, which
is different than the polyculture system of Serfling [19].
The polyculture system should produce an effluent low in BOD,
suspended solids, and nitrogen. The rapid infiltration system will
provide additional removals of these constituents and will remove
phosphorus down to less than 1 mg/L.

Overland Flow Plus Hyacinths. This combination of treatment
processes could be very attractive for small- to medium-sized
communities particularly in the southeast. The system consists of
preliminary screening and grit removal, chemical addition, overland
flow, and water hyacinth ponds. As practiced by Peters and Lee, the
addition of alum (or ferric chloride) to the screened wastewater ahead

481

of overland flow will precipitate phosphorus on the overland flow slopes
[20]. Overland flow will remove BOD and nitrogen to the required
levels. The hyacinth ponds provide further removals of BOD, suspended
solids, and nitrogen.

Cost Comparison. The comparative costs for these two flowsheets
and for slow rate land treatment and AWT are presented in Table 10. The
capital costs are presented in units of $/gal of design capacity. The
slow rate system requires 160 acres of land compared to 43 acres for the
polyculture-rapid infiltration flowsheet and 70 acres for the overland
flow-hyacinth system. The AWT system consists of activated sludge,
chemical precipitation of phosphorus, and filtration plus nitrification
and denitrification for nitrogen removal.

Table 10. COST COMPARISON OF l-mgd
NUTRIENT REMOVAL SYSTEMS

Capital cost, Total cost,
Treatment system $/gal of capacity �/1,000 gal

Oxidation pond plus polyculture
plus rapid infiltration 1.32 51
Overland flow plus water hyacinths 1.81 79
Slow rate land treatment 3.44 110
AWT 6.28 240

In Table 10, the costs are representative of favorable conditions
for all flowsheets including land cost at $4,000/acre. For the l-mgd
system, the system with the lowest costs is the oxidation pond,
polyculture, rapid infiltration flowsheet, which is 21% of the AWT cost.
Many other flowsheets could be developed that would have lower capital
cost than the AWT system selected and it is doubtful that at 1 mgd the
AWT system, costing over $6 per gallon of capacity, would be affordable.

Land Cost Sensitivity. All four flowsheets were retained for
comparison of costs at 10 mgd. The total costs of the systems are
compared for land costs of $4,000 and $10,000/acre in Table 11. The
slow rate system with the most land increases in cost by 38%; however,
the costs of the two aquatic-land treatment systems only increase by 16%.

Table 11. COST COMPARISON OF 10-mgd
NUTRIENT REMOVAL SYSTEMS
l/1,000 gal

Treatment system Land = $4,000/acre Land = $10,000/acre

Oxidation pond plus polyculture
plus rapid infiltration 24 28
Overland flow plus water hyacinths 37 43
Slow rate land treatment 63 87
AWT 110 110

482

SUMMARY AND CONCLUSIONS

Aquatic treatment systems, although still in the development stage
in most areas, offer low-cost, low-energy solutions for wastewater
treatment. For advanced secondary treatment (BOD and suspended solids,
10 mg/L; no nutrient removal), combinations of oxidation ponds with
water hyacinths or wetlands are cost effective compared at 1 mgd with
land treatment or conventional treatment. For the lowest cost flowsheet
examined, the land cost can reach $115,000/acre before the conventional
activated sludge system becomes economically competitive.
For advanced wastewater treatment (nitrogen, 3 mg/L; phosphorus, 1
rag/L), aquatic systems alone have not been developed technically to
achieve the same standards. The aquatic processes can, however, be
integrated with land treatment and oxidation ponds to achieve this high
quality of effluent. In the cases studied, the combined aquatic-land
treatment systems were less expensive than land or conventional
treatment at 1 and 10 mgd. As aquatic systems become further developed
and demonstrated, the costs will become more firmly established. In
addition, the economic benefits (such as from compost, fertilizer, soil
conditioners, or biogas) may offset some of the costs of wastewater
treatment in the future.

REFERENCES

1. Small, M.M. Wetlands Wastewater Treatment Systems. Proceedings of
the International Symposium on Land Treatment of Wastewater, Vol.
2, pp 141-147. August 1979.

2. Wolverton, B.C. and R.C. McDonald. Upgrading Facultative Waste
Stabilization Ponds with Vascular Aquatic Plants. Journal WPCF.
Vol. 51, No. 2, pp 305-313. February 1979.

3. Dinges, R. A Proposed Integrated Biological Wastewater Treatment
System. In: Biological Control of Water Pollution. Tourbier, J.
and R.W. Pierson, Jr. (ed.). University of Pennsylvania Press, pp
225-230. 1976.

4. Golueke, C.G. Aquaculture in Resource Recovery. Compost
Science/Land Utilization. Vol. 20, No. 3, pp 16-23. 1979.

5. De Jong, J. The Purification of Wastewater with the Aid of Rush or
Reed Ponds. In: Biological Control of Water Pollution. Tourbier,
J. and R.W. Pierson, Jr. (ed.). University of Pennsylvania Press,
pp 133-139. 1976.

6. Kadlec, R.H. Research Results for Engineering Design of the
Wetlands Treatment System, Houghton, Lake Michigan. Presented at
the Seminar on Aquaculture Systems for Wastewater Treatment.
University of California, Davis. September 1979.

483

7. Dinges, R. Upgrading Stabilization Pond Effluent by Water Hyacinth
Culture. Journal WPCF. Vol. 50, No. 5, pp 833-845. 1978.

8. Dinges, R. Development of Hyacinth Wastewater Treatment Systems in
Texas. Presented at the Seminar on Aquaculture Systems for
Wastewater Treatment. University of California, Davis. September
1979.

9. Cornwell, D.A., et al. Nutrient Removal by Water Hyacinths.
Journal WPCF. Vol. 49, No. 1, pp 57-65. 1977.

10. Bagnall, L.O., et al. Feed and Fiber from Effluent-Grown Water
Hyacinth. In: Wastewater Use in the Production of Food and Fiber,
EPA-660/2-74-041. pp 115-141. June 1974.

11. Stewart, E.A. III. Water Hyacinths for Advanced Wastewater
Treatment - Trickling Filter Plants. Presented at the Seminar on
Aquaculture Systems for Wastewater Treatment. University of
California, Davis. September 1979.

12. Van Der Weert, R. and G.E. Kamerling. Evapotranspiration of Water
Hyacinth. Journal of Hydrology. Vol. 22, pp 201-212. 1974.

13. Benton, A.R., Jr., et al. Evapotranspiration from Water Hyacinth
in Texas Reservoirs. Water Resources Bulletin. Vol. 14, No. 4, pp
919-930. August 1978.

14. Stowell, R., et al. The Use of Aquatic Plants and Animals for the
Treatment of Wastewater. Department of Civil Engineering,
University of California, Davis. September 1979.

15. Coleman, M.S., et al. Aquaculture as a Means to Achieve Effluent
Standards. In: Wastewater Use in the Production of Food and
Fiber. EPA-600/2-74-041. pp 199-214. June 1974.

16. Henderson, U.B. and F.S. Wert. Economic Assessment of Wastewater
Aquaculture Treatment Systems. Environmental Protection Agency,
Office of Research and Development. EPA-600/2-76-293. December
1976.

17. Crites, R.W., M.J. Dean, and H.L. Selznick. Land Treatment vs. AWT -
How Do Costs Compare? Water and Wastes Engineering. Vol. 16, No.
8, pp 16-19, 42. August 1979.

18. Reed, S.C., et al. Costs of Land Treatment Systems. Environmental
Protection Agency, Office of Water Program Operations. EPA-430/9-
75-003. September 1979.

484

19. Serfling, S.A. and D. Mendola. The Solar Aquacell AWT Lagoon
System for the City of Hercules, California. Proceedings of the
Water Reuse Symposium, Vol. 1, pp 671-680, Washington, D.C. March
1979.

20. Peters, R.E. and C.R. Lee. Field Investigations of Advanced
Treatment of Municipal Wastewater by Overland Flow. Proceedings of
the International Symposium on Land Treatment of Wastewater, Vol.
2. Hanover, N.H. pp 45-60. August 1978.

485