[Federal Register Volume 69, Number 125 (Wednesday, June 30, 2004)]
[Proposed Rules]
[Pages 39383-39392]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-14826]



[[Page 39383]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[OAR-2003-0191; FRL-7780-7]
RIN 2060-AE-94


Appendix C to 40 CFR Part 63--Determination of the Fraction 
Biodegraded (Fbio) in a Biological Treatment Unit

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule; amendments.

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SUMMARY: This action proposes amendments to appendix C to 40 CFR part 
63. Appendix C defines the procedures for an owner or operator of a 
facility that generates wastewater to calculate the site-specific 
fraction of organic compounds biodegraded (Fbio) in a 
biological treatment unit. The proposed amendments to Appendix C would 
add a non-speciated test procedure to the batch test procedures for use 
in demonstrating compliance with wastewater rules that regulate 
volatile organic compounds (VOC), such as the synthetic organic 
chemical manufacturing industry (SOCMI) Wastewater new source 
performance standards (NSPS). The proposed amendments would also make 
minor editorial changes throughout appendix C.

DATES: Comments. Comments must be received on or before August 30, 
2004.
    Public Hearing. If anyone contacts EPA requesting to speak at a 
public hearing by July 20, 2004, a public hearing will be held on July 
30, 2004. Persons interested in presenting oral testimony or inquiring 
as to whether a hearing is to be held should contact JoLynn Collins, 
Waste and Chemical Processes Group, Emissions Standards Division (C439-
03), U.S. EPA, Research Triangle Park, NC 27711, telephone (919) 541-
5671 at least 2 days in advance of the public hearing.

ADDRESSES: Comments. Submit your comments, identified by Docket ID No. 
OAR-2003-0191, by one of the following methods to the docket. If 
possible, also send a copy of your comments to Mary Tom Kissell by 
either mail or e-mail as identified in the FOR FURTHER INFORMATION 
CONTACT section.
    1. Federal eRulemaking Portal: http://www.regulations.gov. Follow 
the on-line instructions for submitting comments.
    2. Agency Web site: http://www.epa.gov/edocket. EDOCKET, EPA's 
electronic public docket and comment system, is EPA's preferred method 
for receiving comments. Follow the on-line instructions for submitting 
comments.
    3. Mail: Air Docket, Environmental Protection Agency, Mailcode: 
6102T, 1200 Pennsylvania Ave., NW., Washington, DC 20460. In addition, 
please mail a copy of your comments on the information collection 
provisions to the Office of Information and Regulatory Affairs, Office 
of Management and Budget (OMB), Attn: Desk Officer for EPA, 725 17th 
St. NW., Washington, DC 20503.
    4. Hand Delivery: Air Docket, Room B-102, Environmental Protection 
Agency, 1301 Constitution Avenue, NW, Washington, DC 20460. Such 
deliveries are only accepted during the Docket's normal hours of 
operation, and special arrangements should be made for deliveries of 
boxed information.
    Instructions. Direct your comments to Docket ID No. OAR-2003-0191. 
The EPA's policy is that all comments received will be included in the 
public docket without change and may be made available online at http://www.epa.gov/edocket, including any personal information provided, 
unless the comment includes information claimed to be Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. Do not submit information that you consider to 
be CBI or otherwise protected through EDOCKET, regulations.gov, or e-
mail. The EPA EDOCKET and the Federal regulations.gov Web sites are 
``anonymous access'' systems, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an e-mail comment directly to EPA without 
going through EDOCKET or regulations.gov, your e-mail address will be 
automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
may not be able to consider your comment. Electronic files should avoid 
the use of special characters, any form of encryption, and be free of 
any defects or viruses.
    Docket. All documents in the docket are listed in the EDOCKET index 
at http://www.epa.gov/edocket. Although listed in the index, some 
information is not publicly available, i.e., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the Internet and will be 
publicly available only in hard copy form. Publicly available docket 
materials are available either electronically in EDOCKET or in hard 
copy at the Air and Radiation Docket, EPA/DC, EPA West, Room B102, 1301 
Constitution Ave., NW, Washington, DC. This docket facility is open 
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal 
holidays. The Air and Radiation Docket telephone number is (202) 566-
1742. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., 
Monday through Friday, excluding legal holidays. The telephone number 
for the Public Reading Room is (202) 566-1744.
    Public Hearing. If timely requests to speak at a public hearing are 
received, a public hearing will be held at the EPA Office of 
Administration Auditorium, Research Triangle Park, North Carolina.
    Persons interested in attending the public hearing must call JoLynn 
Collins to verify the time, date, and location of the hearing. The 
public hearing will provide interested parties the opportunity to 
present data, views, or arguments concerning these proposed amendments.

FOR FURTHER INFORMATION CONTACT: Mary Tom Kissell, Office of Air and 
Radiation, Emission Standards Division (C439-03), U.S. EPA, Research 
Triangle Park, North Carolina 27711, telephone number (919) 541-4516, 
fax number (919) 685-3219, e-mail: [email protected].

SUPPLEMENTARY INFORMATION: Regulated Entities. The proposed amendments 
could possibly apply to a large number of industries that could be 
using the provisions of 40 CFR part 63, appendix C, to demonstrate 
compliance with an air standard. Therefore, we have not listed specific 
affected industries or their North American Industrial Classification 
System (NAICS) codes here. If you have any questions regarding the 
applicability of this action to a particular entity, consult the person 
listed in the preceding FOR FURTHER INFORMATION CONTACT section.
    Outline. The information presented in the preamble is organized as 
follows:

I. Background
II. Summary of the Proposed Amendments
III. Statutory and Executive Order Reviews
    A. Executive Order 12866, Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132, Federalism

[[Page 39384]]

    F. Executive Order 13175, Consultation and Coordination with 
Indian Tribal Governments
    G. Executive Order 13045, Protection of Children from 
Environmental Health & Safety Risks
    H. Executive Order 13211, Actions Concerning Regulations that 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer Advancement Act

I. Background

    Appendix C to 40 CFR part 63 provides procedures for calculating 
Fbio in a biological treatment system. The appendix 
currently contains five procedures for determining Fbio: 
bench-top reactors, site-specific system performance data, inlet and 
outlet concentration data, batch tests, and multiple zone concentration 
measurements. Each of the procedures in appendix C are compound-
specific (i.e., the individual compound fraction biodegraded 
(Fbio) is determined for each identified compound and then 
summed to obtain an overall Fbio). However, in developing 
the new source performance standards for wastewater sources in the 
synthetic organic chemical manufacturing industry, we realized that 
Fbio determinations on an individual compound basis may be 
problematic for sources demonstrating compliance for large numbers of 
undefined VOC.
    Wastewater streams from SOCMI processes can contain hundreds of 
organic wastewater compounds (OWWC). For these wastewater streams, 
identifying all (or the predominant constituents) of the OWWC would 
require costly analytical testing. To provide for a more cost-effective 
evaluation of wastewater streams with multiple OWWC, the proposed 
amendments to appendix C to 40 CFR part 63 add a procedure for 
determining an overall Fbio that does not require 
identification of specific OWWC.

II. Summary of the Proposed Amendments

    The proposed amendments to appendix C to 40 CFR part 63 add a non-
speciated, aerated draft tube reactor test to the existing batch test 
procedures described in section III.D of appendix C. The proposed non-
speciated test procedure uses the same approach as the aerated reactor 
test, but also includes procedures that are related to evaluating 
individual components in a wastewater stream without having to identify 
these components or make separate measurements of the characteristics 
of the components.
    The proposed test procedure relies on establishing correlations 
between peak areas of unidentified compounds resulting from gas 
chromatography (GC) analysis with the measured concentrations of the 
unidentified compounds in the draft tube headspace. Automated gas 
sampling or solid phase microextraction (SPME) fibers are used to 
collect samples of the gas in the headspace of the draft tube over the 
time period of the test. Compounds in the gas samples are measured 
using a gas chromatography/flame ionization detector (GC/FID).
    The change in each VOC concentration in the headspace of the draft 
tube is related to the decrease in aqueous phase concentration of each 
VOC over time. This correlation is used to calculate biodegradation 
rates for each VOC. Also, an overall Fbio for the biological 
treatment system is calculated from the sum of the individual organic 
compound concentrations and individual Fbio values. Appendix 
C to 40 CFR part 63 allows the use of manual or computer-assisted 
methods to analyze the GC concentration data.
    Today's proposed non-speciated aerated draft tube reactor test 
method is an appropriate addition to appendix C to 40 CFR part 63 to 
provide a more cost-effective option for compliance demonstrations for 
activated sludge biological treatment units affected by wastewater 
rules regulating VOC. While we consider this to be a cost-effective 
option, the non-speciated method also provides an accurate procedure 
for demonstrating biodegradation as opposed to volatilization for an 
activated sludge biological unit. Although appropriate for rules such 
as the proposed SOCMI Wastewater NSPS that would regulate OWWC, the 
non-speciated aerated method may not be appropriate for other rules. In 
the case of the proposed SOCMI Wastewater NSPS, the regulated 
pollutants would be OWWC which comprise all of the organic compounds in 
the wastewater streams that may volatilize, i.e., compounds with a 
Henry's law constant greater than 0.1 atmosphere per mole fraction. For 
rules requiring destruction of hazardous air pollutants (HAP), other 
appendix C procedures are preferred because they require identification 
and quantification of HAP, ensuring the overall Fbio 
reflects the actual destruction of the HAP and not the average of all 
the organic compounds present in the wastewater. Therefore, today's 
proposed non-speciated aerated draft tube reactor test method may only 
be used to comply with rules that regulate VOC, such as the SOCMI 
Wastewater NSPS.
    In addition to the non-speciated aerated draft tube reactor test, 
the proposed amendments also make minor revisions to clarify the 
existing batch test procedures in section III.D of appendix C to 40 CFR 
part 63. We are clarifying that the batch test procedures are headspace 
characterization methods. Also, we are clarifying that the equilibrium 
verification required by the aerated reactor test must be demonstrated 
for one or more of the most volatile compounds to be tested for 
biodegradation.

III. Statutory and Executive Order Reviews

A. Executive Order 12866, Regulatory Planning and Review

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), EPA 
must determine whether the regulatory action is ``significant'' and, 
therefore, subject to review by the OMB and the requirements of the 
Executive Order. The Executive Order defines ``significant regulatory 
action'' as one that is likely to result in a rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or tribal governments or 
communities;
    (2) create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs, or the rights and obligations of 
recipients thereof; or
    (4) raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    We have determined that the proposed amendments are not a 
``significant regulatory action'' under the terms of Executive Order 
12866 and do not impose any additional control requirements. The 
proposed amendments add an additional, potentially less-costly option 
for compliance demonstration for certain biological treatment units. 
Therefore, the proposed amendments are not subject to review by OMB.

B. Paperwork Reduction Act

    The proposed amendments to appendix C to 40 CFR part 63 do not 
impose or change any information collection requirements. Therefore, 
the requirements of the Paperwork Reduction Act do not apply to the 
proposed amendments.

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C. Regulatory Flexibility Act

    The Regulatory Flexibility Act generally requires an agency to 
prepare a regulatory flexibility analysis of any rule subject to notice 
and comment rulemaking requirements under the Administrative Procedure 
Act or any other statute unless the agency certifies that the rule will 
not have a significant impact on a substantial number of small 
entities. Small entities include small businesses, small government 
organizations, and small government jurisdictions.
    For purposes of assessing the impacts of today's rule on small 
entities, small entity is defined as: (1) A small business with up to 
1,000 employees; (2) a small governmental jurisdiction that is a 
government of a city, county, town, school district or special district 
with a population of less than 50,000; and (3) a small organization 
that is any not-for-profit enterprise which is independently owned and 
operated and is not dominant in its field.
    After considering the economic impacts of today's proposed rule on 
small entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. Today's 
proposed amendments do not increase the cost of compliance because: (1) 
The proposed amendments do not impose requirements independent of the 
proposed SOCMI Wastewater NSPS; (2) we proposed using appendix C to 40 
CFR part 63 to demonstrate compliance with the proposed SOCMI 
Wastewater NSPS in the supplement to the proposed rule; (3) the cost of 
compliance demonstrations is accounted for in the proposed SOCMI 
Wastewater NSPS; and (4) the procedure we are proposing to add to 
appendix C provides another, less expensive, alternative to the 
procedures currently available in appendix C. We continue to be 
interested in the potential impacts of the proposed rule on small 
entities and welcome comments on issues related to such impacts.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (URMA), Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and tribal 
governments and the private sector. Under section 202 of the UMRA, the 
EPA generally must prepare a written statement, including a cost-
benefit analysis, for proposed and final rules with ``Federal 
mandates'' that may result in expenditures by State, local, and tribal 
governments, in the aggregate, or by the private sector, of $100 
million or more in any 1 year. Before promulgating an EPA rule for 
which a written statement is needed, section 205 of the UMRA generally 
requires EPA to identify and consider a reasonable number of regulatory 
alternatives and adopt the least costly, most cost-effective, or least 
burdensome alternative that achieves the objectives of the rule. The 
provisions of section 205 do not apply when they are inconsistent with 
applicable law. Moreover, section 205 allows EPA to adopt an 
alternative other than the least costly, most cost-effective, or least 
burdensome alternative if the Administrator publishes with the final 
rule an explanation why that alternative was not adopted. Before EPA 
establishes any regulatory requirements that may significantly or 
uniquely affect small governments, including tribal governments, it 
must have developed, under section 203 of the UMRA, a small government 
agency plan. The plan must provide for notifying potentially affected 
small governments, enabling officials of affected small governments to 
have meaningful and timely input in the development of EPA's regulatory 
proposals with significant Federal intergovernmental mandates, and 
informing, educating, and advising small governments on compliance with 
the regulatory requirements.
    The EPA has determined that the proposed amendments do not contain 
a Federal mandate that may result in expenditures of $100 million or 
more for State, local, and tribal governments, in the aggregate, or the 
private sector in any 1 year. Thus, the proposed amendments are not 
subject to the requirements of section 202 and 205 of the UMRA. In 
addition, EPA has determined that the proposed amendments do not 
contain regulatory requirements that might significantly or uniquely 
affect small governments because the proposed amendments do not impose 
any additional regulatory requirements. Therefore, the proposed 
amendments are not subject to the requirements of section 203 of the 
UMRA.

E. Executive Order 13132, Federalism

    Executive Order 13132 (64 FR 43255, August 10, 1999) requires EPA 
to develop an accountable process to ensure ``meaningful and timely 
input by State and local officials in the development of regulatory 
policies that have federalism implications.'' ``Policies that have 
federalism implications'' is defined in the Executive Order to include 
regulations that have ``substantial direct effects on the States, on 
the relationship between the national government and the States, or on 
the distribution of power and responsibilities among the various levels 
of government.''
    The proposed amendments do not have federalism implications. The 
proposed amendments will not have substantial direct effects on the 
States, on the relationship between the national government and the 
States, or on the distribution of power and responsibilities among the 
various levels of government, as specified in Executive Order 13132. 
The proposed amendments will not impose substantial direct compliance 
costs on State or local governments, and they will not preempt State 
law. Thus, Executive Order 13132 does not apply to the proposed 
amendments.

F. Executive Order 13175, Consultation and Coordination With Indian 
Tribal Governments

    Executive Order 13175 (65 FR 67249, November 9, 2000) requires EPA 
to develop an accountable process to ensure ``meaningful and timely 
input by tribal officials in the development of regulatory policies 
that have tribal implications.''
    The proposed amendments do not have tribal implications and will 
not have substantial direct effects on tribal governments, on the 
relationship between the Federal government and Indian tribes, or on 
the distribution of power and responsibilities between the Federal 
government and Indian tribes. Thus, Executive Order 13175 does not 
apply to the proposed amendments.

G. Executive Order 13045, Protection of Children From Environmental 
Health & Safety Risks

    Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any 
rule that (1) is determined to be ``economically significant'' as 
defined under Executive Order 12866, and (2) concerns an environmental 
health or safety risk that EPA has reason to believe may have a 
disproportionate effect on children. If the regulatory action meets 
both criteria, the EPA must evaluate the environmental health or safety 
effects of the planned rule on children, and explain why the planned 
regulation is preferable to other potentially effective and reasonably 
feasible alternatives considered by EPA.
    The EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that are based on health or safety risks, such that 
the analysis required under section 5-501 of the Executive Order has 
the potential to influence the rule. The proposed amendments are not 
subject to

[[Page 39386]]

Executive Order 13045 because they are based on technology performance 
and not on health and safety risks. Also, the proposed amendments are 
not ``economically significant.''

H. Executive Order 13211, Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    The proposed amendments are not subject to Executive Order 13211 
(66 FR 28355, May 22, 2001) because they are not a significant 
regulatory action under Executive Order 12866 and because they will not 
have an adverse effect on the supply, distribution, or use of energy.

I. National Technology Transfer Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act (NTTAA) of 1995, (Public Law 104-113; 15 U.S.C. 272 note) directs 
EPA to use voluntary consensus standards in their regulatory and 
procurement activities unless to do so would be inconsistent with 
applicable law or otherwise impractical. Voluntary consensus standards 
are technical standards (e.g., material specifications, test methods, 
sampling procedures, business practices) developed or adopted by one or 
more voluntary consensus bodies. The NTTAA directs EPA to provide 
Congress, through annual reports to OMB, with explanations when an 
agency does not use available and applicable voluntary consensus 
standards.
    The proposed amendments include technical standards and 
requirements for taking measurements. Consistent with the NTTAA, we 
conducted searches for applicable voluntary consensus standards that 
could be used in addition to the method proposed in this action by 
searching the National Standards System Institute (NSSN) database. We 
searched for methods and tests required by the proposed amendments, all 
of which are methods or tests previously promulgated. No potentially 
equivalent methods for the methods and tests in the proposal were found 
in the NSSN database search. Therefore, we do not propose to use any 
voluntary consensus standards. The search and review results are 
documented in Dockets No. OAR-2003-0191 and A-94-32.

List of Subjects in 40 CFR Part 63

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Hazardous substances, Intergovernmental 
relations, Reporting and recordkeeping requirements.

    Dated: June 24, 2004.
Michael O. Leavitt,
Administrator.

    For reasons cited in the preamble, title 40, chapter I, part 63 of 
the Code of Federal Regulations is proposed to be amended as follows:

PART 63--[AMENDED]

    1. The authority citation for part 63 continues to read as follows:

    Authority: 42 U.S.C. 7401 et seq.

    2. Appendix C is amended by revising Section III Procedures for 
Determination of Fbio introductory text to read as follows:

Appendix C to Part 63--Determination of the Fraction Biodegraded 
(Fbio) in a Biological Treatment Unit

* * * * *

III. Procedures for Determination of Fbio

* * * * *
    Procedure 4 explains three types of batch tests which may be 
used to estimate the first order biodegradation rate constant. * * *
* * * * *
    3. Appendix C is amended by revising section III.D to read as 
follows:

D. Batch Tests (Procedure 4)

    Three types of batch tests which may be used to determine 
kinetic parameters are: (1) The aerated reactor test, (2) the sealed 
reactor test, and (3) the non-speciated aerated draft tube reactor 
test. The non-speciated aerated draft reactor test is appropriate 
for compliance demonstrations with rules that regulate volatile 
organic compounds (VOC). Where there is a limited specific list of 
HAP compounds of concern one of the other batch tests or procedures 
is preferable. The aerated reactor test is also known as the BOX 
test (batch test with oxygen addition). The sealed reactor test is 
also known as the serum bottle test. These batch tests should be 
conducted only by persons familiar with procedures for determining 
biodegradation kinetics. Detailed discussions of batch procedures 
for determining biodegradation kinetic parameters can be found in 
references 1-4. A detailed discussion of the non-speciated aerated 
draft tube reactor test can be found in reference 9.
    For the batch test approaches, a biomass sample from the 
activated sludge unit of interest is collected, aerated, and stored 
for no more than 4 hours prior to testing. To collect sufficient 
data when biodegradation is rapid, it may be necessary to dilute the 
biomass sample. If the sample is to be diluted, the biomass sample 
shall be diluted using treated effluent from the activated sludge 
unit of interest to a concentration such that the biodegradation 
test will last long enough to make at least six concentration 
measurements. It is recommended that the tests not be terminated 
until the compound concentration falls below the limit of 
quantitation (LOQ). Measurements that are below the LOQ should not 
be used in the data analysis. Biomass concentrations shall be 
determined using standard methods for measurement of mixed liquor 
volatile suspended solids (MLVSS) (reference 5).
    The change in concentration of a test compound may be monitored 
by either measuring the concentration in the liquid or in the 
reactor headspace. The analytical technique chosen for the test 
should be as sensitive as possible. For the batch test procedures 
using headspace characterization described in this section, 
equilibrium conditions must exist between the liquid and gas phases 
of the experiments because the data analysis procedures are based on 
this premise. To use the headspace sampling approach, the reactor 
headspace must be in equilibrium with the liquid so that the 
headspace concentrations can be correlated with the liquid 
concentrations. Before the biodegradation testing is conducted using 
headspace analysis, the equilibrium assumption must be verified. A 
discussion of the equilibrium assumption verification is given below 
in sections D.1 and D.2 since different approaches are required for 
the two types of batch tests.
    To determine biodegradation kinetic parameters in a batch test, 
it is important to choose an appropriate initial substrate 
(compound(s) of interest) concentration for the test. The outcome of 
the batch experiment may be influenced by the initial substrate 
(So) to biomass (Xo) ratio (see references 3, 
4, and 6). This ratio is typically measured in chemical oxygen 
demand (COD) units. When the So/Xo ratio is 
low, cell multiplication and growth in the batch test is negligible 
and the kinetics measured by the test are representative of the 
kinetics in the activated sludge unit of interest. The 
So/Xo ratio for a batch test is determined 
with the following equation:
[GRAPHIC] [TIFF OMITTED] TP30JN04.016

Where:

So/Xo = initial substrate to biomass ratio on 
a COD basis
Si = initial substrate concentration in COD units(g COD/
liter)
X = biomass concentration in the batch test (g MLVSS/liter)
1.42 = Conversion factor to convert to COD units

    For the batch tests described in this section, the 
So/Xo ratio (on a COD basis) must be initially 
less than 0.5.
    1. Aerated Reactor Test. An aerated draft tube reactor may be 
used for the biokinetics testing (as an example see Figure 2 of 
appendix C). Other aerated reactor configurations may also be used. 
Air is bubbled through a porous frit at a rate sufficient to aerate 
and keep the reactor uniformly mixed. Aeration rates typically vary 
from 50 to 200 milliter per minute (ml/min) for a 1 liter system. A 
mass flow rate controller is used to carefully control the air flow 
rate because it is important to have an accurate measure of this 
rate. The dissolved oxygen (DO) concentration in the system must not 
fall below 2 milligram per liter (mg/liter) so that the 
biodegradation observed will

[[Page 39387]]

not be DO-limited. Once the air flow rate is established, the test 
mixture (or compound) of interest is then injected into the reactor 
and the concentration of the compound(s) is monitored over time. 
Concentrations may be monitored in the liquid or in the headspace. A 
minimum of six samples shall be taken over the period of the test. 
However, it is recommended to collect samples until the compound 
concentration falls below the LOQ. If liquid samples are collected, 
they must be small enough such that the liquid volume in the batch 
reactor does not change by more than 10 percent.
    Before conducting experiments with biomass, it is necessary to 
verify the equilibrium assumption using one or more of the more 
volatile components from the list of volatile components that will 
be tested. A demonstration of equilibrium with the most volatile 
components that will be tested is expected to assure that 
equilibrium is also achieved with the less volatile components. The 
number of volatile components needed to demonstrate equilibrium 
depends on experimental uncertainty, literature measurement 
uncertainty, and the availability of previous demonstrations of 
equilibrium using similar equipment. If the most volatile 
component(s) that will be tested have a Henry's constant of less 
than 0.1 (y/x), then a demonstration of equilibrium with those 
components is not required if a previous demonstration of 
equilibrium is available using similar equipment. The equilibrium 
assumption can be verified by conducting a stripping experiment 
using the effluent (no biomass) from the activated sludge unit of 
interest. Effluent is filtered with a 0.45 micrometer (um) or 
smaller filter and placed in the draft tube reactor. Air is sparged 
into the system and the compound concentration in the liquid or 
headspace is monitored over time. This test with no biomass will 
provide an estimate of the Henry's law constant. If the system is at 
equilibrium, the Henry's law constant may be estimated with the 
following equation:

-ln(C/Co)=(GKeq/V)t (Eqn. App. C-2)

Where:

C = concentration at time, t (min)
Co = concentration at t = 0
G = volumetric gas flow rate (ml/min)
V = liquid volume in the batch reactor (ml)
Keq = Henry's law constant (mg/L-gas)/(mg/L-liquid)
t = time (min)

    A plot of -ln(C/Co) as a function of t will have a 
slope equal to GKeq/V. The equilibrium assumption can be 
verified by comparing the experimentally determined Keq 
for the system to literature values of the Henry's Law constant 
(including those listed in this appendix). If Keq does 
not match the Henry's law constant, Keq shall be 
determined from analysis of the headspace and liquid concentration 
in a batch system.
    The concentration of a compound decreases in the bioreactor due 
to both biodegradation and stripping. Biodegradation processes are 
typically described with a Monod model. This model and a stripping 
expression are combined to give a mass balance for the aerated draft 
tube reactor:
[GRAPHIC] [TIFF OMITTED] TP30JN04.007

Where:

s = test compound concentration, mg/liter
G = volumetric gas flow rate, liters/hr
Keq = Henry's Law constant measured in the system, (mg/
liter gas)/(mg/liter liquid)
V = volume of liquid in the reactor, liters
X = biomass concentration (g MLVSS/liter)
Qm = maximum rate of substrate removal, mg/g MLVSS/hr
Ks = Monod biorate constant at half the maximum rate, mg/
liter

    Equation App. C-3 can be integrated to obtain the following 
equation:
[GRAPHIC] [TIFF OMITTED] TP30JN04.008

where:
A = GKeqKs + QmVX
B = GKeq
So = test compound concentration at t=0

    This equation is used along with the substrate concentration 
versus time data to determine the best fit parameters (Qm 
and Ks) to describe the biodegradation process in the 
aerated reactor. If the Aerated Reactor test is used, the following 
procedure is used to analyze the data. Evaluate Keq for 
the compound of interest with Form XI. The concentration in the 
vented headspace or liquid is measured as a function of time and the 
data is entered on Form XI. A plot is made from the data and 
attached to the Form XI. Keq is calculated on Form XI and 
the results are contrasted with the expected value of Henry's law 
obtained from Form IX. If the comparison is satisfactory, the 
stripping constant is calculated from Keq, completing 
Form XI. The values of Keq may differ because the 
theoretical value of Keq may not be applicable to the 
system of interest. If the comparison of the calculated 
Keq from the form and the expected value of Henry's law 
is unsatisfactory, Form X can alternatively be used to validate 
Keq. If the aerated reactor is demonstrated to not be at 
equilibrium, either modify the reactor design and/or operation, or 
use another type of batch test. This equilibrium testing must only 
be demonstrated for one or more of the most volatile compounds to be 
tested for biodegradation. Once it is demonstrated that the aerated 
reactor achieves equilibrium, then Form IX is used to adjust 
published or measured Henry's law constants for the other volatile 
compounds to be tested.
    The compound-specific biorate constants are then measured using 
Form XII. The stripping constant that was determined from Form XI 
and a headspace correction factor of 1 are entered on Form XII. The 
aerated reactor biotest may then be run, measuring concentrations of 
each compound of interest as a function of time. If headspace 
concentrations are measured instead of liquid concentrations, then 
the corresponding liquid concentrations are calculated from the 
headspace measurements using the Keq determined on Form 
XI and entered on Form XII.
    The concentration data on Form XII may contain scatter that can 
adversely influence the data interpretation. It is acceptable to 
curve fit the concentration data and enter the concentrations on the 
fitted curve instead of the actual data. If curve fitting is used, 
the curve-fitting procedure must be based upon the Equation App. C-
4. When curve fitting is used, it is necessary to attach a plot of 
the actual data and the fitted curve to Form XII.
    If the stripping rate constant is relatively large when compared 
to the biorate at low concentrations, it may be difficult to obtain 
accurate evaluations of the first-order biorate constant. In these 
cases, either reducing the stripping rate constant by lowering the 
aeration rate, or increasing the biomass concentrations should be 
considered. The final result of the batch testing is the measurement 
of a biorate that can be used to estimate the fraction biodegraded, 
fbio. The number transferred to Form III is obtained from 
Form XII, line 9.
    2. Sealed Reactor Test. This test uses a closed system to 
prevent losses of the test compound by volatilization. This test may 
be conducted using a serum bottle or a sealed draft tube reactor 
(for an example see Figure 3 of appendix C). Since no air is 
supplied, it is necessary to ensure that sufficient oxygen is 
present in the system. The DO concentration in the system must not 
fall below 2 mg/liter so that the biodegradation observed will not 
be DO-limited. As an

[[Page 39388]]

alternative, oxygen may be supplied by electrolysis as needed to 
maintain the DO concentration above 2 mg/liter. The reactor contents 
must be uniformly mixed, by stirring or agitation using a shaker or 
similar apparatus. The test mixture (or compound) of interest is 
injected into the reactor and the concentration is monitored over 
time. A minimum of six samples shall be taken over the period of the 
test. However, it is necessary to monitor the concentration until it 
falls below the LOQ.
    The equilibrium assumption must be verified for the batch 
reactor system that depends on headspace characterization. In this 
case, Keq may be determined by simultaneously measuring 
gas and liquid phase concentrations at different times within a 
given experiment. The equilibrium testing must only be demonstrated 
for one or more of the most volatile component(s) that will be 
tested. A constant ratio of gas/liquid concentrations indicates that 
equilibrium conditions are present and Keq is not a 
function of concentration. This ratio is then taken as the 
Keq for the specific component(s) in the test. It is not 
necessary to measure Keq for each experiment. If the 
ratio is not constant, the equilibrium assumption is not valid and 
it is necessary to (1) increase mixing energy for the system and 
retest for the equilibrium assumption, or (2) use a different type 
of test that does not depend on headspace characterization (for 
example, a collapsible volume reactor).
    The concentration of a compound decreases in the bioreactor due 
to biodegradation according to Equation App. C-5:
[GRAPHIC] [TIFF OMITTED] TP30JN04.009

where:

s = test compound concentration (mg/liters)
Vl = the average liquid volume in the reactor (liters)
Vg = the average gas volume in the reactor (liters)
Qm = maximum rate of substrate removal (mg/g MLVSS/hr)
Keq = Henry's Law constant determined for the test, (mg/
liter gas)/(mg/liter liquid)
Ks = Monod biorate constant at one-half the maximum rate 
(mg/liter)
t = time (hours)
X = biomass concentration (g MLVSS/liter)
So = test compound concentration at time t=0

    Equation App. C-5 can be solved analytically to give:
    [GRAPHIC] [TIFF OMITTED] TP30JN04.010
    
    This equation is used along with the substrate concentration 
versus time data to determine the best fit parameters (Qm 
and Ks) to describe the biodegradation process in the 
sealed reactor.
    If the sealed reactor test is used, Form X is used to determine 
the headspace correction factor. The disappearance of a compound in 
the sealed reactor test is slowed because a fraction of the compound 
is not available for biodegradation because it is present in the 
headspace. If the compound is almost entirely in the liquid phase, 
the headspace correction factor is approximately one. If the 
headspace correction factor is substantially less than one, improved 
mass transfer or reduced headspace may improve the accuracy of the 
sealed reactor test. A preliminary sealed reactor test must be 
conducted to test the equilibrium assumption. As the compound of 
interest is degraded, simultaneous headspace and liquid samples 
should be collected and Form X should be used to evaluate 
Keq. The ratio of headspace to liquid concentrations must 
be constant in order to confirm that equilibrium conditions exist. 
If equilibrium conditions are not present, additional mixing or an 
alternate reactor configuration may be required.
    The compound-specific biorate constants are then calculated 
using Form XII. For the sealed reactor test, a stripping rate 
constant of zero and the headspace correction factor that was 
determined from Form X are entered on Form XII. The sealed reactor 
test may then be run, measuring the concentrations of each compound 
of interest as a function of time. If headspace concentrations are 
measured instead of liquid concentrations, then the corresponding 
liquid concentrations are calculated from the headspace measurements 
using Keq from Form X and entered on Form XII.
    The concentration data on Form XII may contain scatter that can 
adversely influence the data interpretation. It is acceptable to 
curve fit the concentration data and enter the concentrations on the 
fitted curve instead of the actual data. If curve fitting is used, 
the curve-fitting procedure must be based upon Equation App. C-6. 
When curve fitting is used, it is necessary to attach a plot of the 
actual data and the fitted curve to Form XII.
    If a sealed collapsible reactor is used that has no headspace, 
the headspace correction factor will equal 1, but the stripping rate 
constant may not equal 0 due to diffusion losses through the reactor 
wall. The ratio of the rate of loss of compound to the concentration 
of the compound in the reactor (units of per hour) must be 
evaluated. This loss ratio has the same units as the stripping rate 
constant and may be entered as the stripping rate constant on line 1 
of Form XII.
    If the loss due to diffusion through the walls of the 
collapsible reactor is relatively large when compared to the biorate 
at low concentrations, it may be difficult to obtain accurate 
evaluations of the first-order biorate constant. In these cases, 
either replacing the materials used to construct the reactor with 
materials of low permeability or increasing the biomass 
concentration should be considered.
    The final result of the batch testing is the measurement of a 
biorate that can be used to estimate the fraction biodegraded, 
fbio. The number transferred to Form III is obtained from 
Form XII, line 9.
    The number on Form XII line 9 will equal the Monod first-order 
biorate constant if the full-scale system is operated in the first-
order range. If the full-scale system is operated at concentrations 
above that of the Monod first-order range, the value of the number 
on line 9 will be somewhat lower than the Monod first-order biorate 
constant. With supporting biorate data, the Monod model used in Form 
XII may be used to estimate the effective biorate constant K1 for 
use in Form III.
    If a reactor with headspace is used, analysis of the data using 
Equation App. C-6 is valid only if Vl and Vg 
do not change more than 10 percent (i.e., they can be approximated 
as constant for the duration of the test). Since biodegradation is 
occurring only in the liquid, as the liquid concentration decreases 
it is necessary for mass to transfer from the gas to the liquid 
phase. This may require vigorous mixing and/or reducing the volume 
in the headspace of the reactor.
    If there is no headspace (e.g., a collapsible reactor), Equation 
App. C-6 is independent of Vl and there are no 
restrictions on the liquid volume. If a membrane or bag is used as 
the collapsible-volume reactor, it may be important to monitor for 
diffusion losses in the system. To determine if there are losses, 
the bag should be used without biomass and spiked with the 
compound(s) of interest. The concentration of the compound(s) in the 
reactor should be monitored over time. The data are analyzed as 
described above for the sealed reactor test.
    3. Non-speciated aerated draft tube reactor test. This method is 
appropriate for compliance demonstrations with rules that regulate 
VOC. The aerated draft tube reactor test is used for assessing the 
Fbio for non-speciated VOC. The methods and procedures 
that are used with the Aerated reactor test (described in section 1 
above) are also used

[[Page 39389]]

with the non-speciated draft tube test, with the exception of 
special procedures that are related to the limited information 
available for identifying the waste components, the volatility of 
the components, and the amount of the components that are present in 
the waste. The non-speciated test method described here is based 
upon evaluating individual components in a waste without the need to 
identify the name of the component or make separate measurements of 
the characteristics of the components.
    3.1 Purpose of the method. The following sections identify 
specific purposes for which the non-speciated method is used. For 
each purpose identified in sections 3.1.1 through 3.1.6, a 
correlation between the peak area of the compound in the GC analysis 
and the concentration in the draft tube headspace must be available 
as discussed in section 3.10.
    3.1.1 Henry's law constant for each non-speciated organic 
compound. One run of the non-speciated method without biomass is 
used to obtain estimates of the Henry's law value for each 
individual organic compound identified in the waste. For each 
volatile organic component, correlations of the vapor phase 
concentration and the stripping times are developed. A Henry's law 
value is determined for each component. See section 3.6.
    3.1.2 Non-speciated organic compound concentration. One run of 
the non-speciated method without biomass is used to evaluate the 
individual organic compound concentrations in the waste. The amount 
of each component initially present in the waste is determined from 
the Henry's law value and the correlation between the peak area and 
the gas correlation. See section 3.9.
    3.1.3 Total concentration of non-speciated organic compounds. 
One run of the non-speciated method without biomass is used to 
obtain estimates of the individual organic compound concentrations 
in the waste. These individual concentrations are summed to obtain 
the total concentration of organic compounds. See section 3.11.
    3.1.4 Biodegradation rate for each non-speciated organic 
compound. Two runs of the non-speciated method, one with biomass and 
one without biomass are used to obtain estimates of the 
biodegradation rate for each individual organic compound identified 
in the waste. The stripping rates from the run without 
biodegradation is compared to the air stripping run with 
biodegradation. The difference in the rates of removal in the two 
runs is used to calculate the biodegradation rate. See section 3.7.
    3.1.5 Individual values of fe and fbio for 
each non-speciated organic compound. The use of Form III or an 
equivalent method is used to evaluate the fraction biodegraded 
(individual Fbio) using the Henry's law value for each 
component (3.6), the amount of each component (3.9), and the 
biodegradation rate for each component (3.7), together with the 
characteristics of the biotreatment unit. See section 3.12.
    3.1.6 Overall Fe and Fbio for the total 
concentration of non-speciated organic compounds. The use of Form 
III or an equivalent method is used to evaluate the fraction 
biodegraded (individual fbio) using the Henry's law value 
for each component (3.6), the amount of each component (3.9), and 
the biodegradation rate for each component (3.7), together with the 
characteristics of the biotreatment unit.
    These individual Fbio numbers for each of the 
components are used to obtain an overall Fbio value for 
the overall non-speciated waste. Non-speciated compounds with low 
Henry's law constants of less than 0.1 mol fraction gas per mol 
fraction in liquid at one atmosphere can be excluded from this 
summation.
    A weighted summation of these individual estimates of biological 
and air emission removal is used to obtain an overall 
Fbio and an overall Fe. See section 3.13.
    3.2 Reactor configuration. An aerated draft tube reactor is used 
for the biokinetics testing for the non-speciated reactor test (as 
an example see Figure 2 of appendix C). Other aerated reactor 
configurations may also be used if equivalent to the aerated draft 
tube reactor. Air is bubbled through a porous frit at a rate 
sufficient to aerate and keep the reactor uniformly mixed. A 
discussion of the setup and the operation of the aerated draft tube 
reactor is presented in Section D.1.
    3.3 Reactor sampling. Concentrations of volatile compounds are 
only monitored in the headspace in the non-speciated aerated draft 
tube reactor test. The headspace may be monitored with solid phase 
microextraction (SPME) fibers or with automated gas sampling. A 
minimum of six headspace samples shall be taken over the period of 
the test for each individual run and analyzed by gas chromatography. 
Sufficient gas samples will be taken to provide at least 3 data 
samples for each relevant component for each air stripping run. It 
is necessary to collect enough samples to quantify the 
characteristics of the individual volatile compound peaks in the 
system; therefore, in some cases it is possible to reduce the total 
number of headspace samples by sampling more frequently at the 
beginning of the run.
    3.4 Reactor equilibrium verification. It is necessary to verify 
the equilibrium assumption for the non-speciated aerated draft tube 
reactor test as discussed in section D.1, using Equation C-2.
    A plot of -ln(C/Co) as a function of t will have a 
slope equal to GKeq/V. Verification of equilibrium can be 
performed initially and periodically with a set of known volatile 
compounds with known Henry's law constants. The selection of 
compounds should represent the most volatile compounds in the waste 
stream (at least as great as the experimentally measured Henry's law 
constants for the top 5 percent of the non-speciated components, or 
alternatively with Henry's law constants of 300 y/x). Experimentally 
measured Henry's law values are available from the WATER7 (or any 
subsequent update to the model) data base for a number of compounds. 
In addition, the compounds that are selected for the verification of 
equilibrium should be included in the determination of the SPME 
fiber partition factor. Verification of equilibrium in the non-
speciated aerated draft tube reactor test under each set of 
operating conditions is important because accurate measurement of 
the Henry's law constant is necessary to permit accurate 
characterization of non-speciated peaks. Non-speciated compound 
peaks that demonstrate Henry's law constants less than 0.1 (y/x) in 
the test are excluded from the analysis. If the aerated draft tube 
reactor cannot be demonstrated to be at equilibrium, modify the 
reactor design and/or operation.
    3.5 Two reactor runs. The concentration of a compound in the 
bioreactor is measured in the headspace in two different runs, first 
with air stripping only and then second with both biodegradation and 
air stripping. A first order biodegradation rate model is used to 
model the biodegradation in the aerated draft tube reactor. Since 
the measurement of the first order biodegradation rate constant is a 
function of concentration, it is important to have concentrations of 
non-speciated compounds in this test that closely represent the 
conditions in the full-scale biodegradation unit that you are 
evaluating. Since the components and concentrations are generally 
unknown for this non-speciated method, samples of actual wastewater 
should be obtained from the applicable location in the full-scale 
facility, or as close to these conditions as practicable, such as a 
sample of wastewater from a pilot plant, a full-scale process from 
another site, etc. This model and a stripping expression are 
combined to give a mass balance for the aerated draft tube reactor:

[GRAPHIC] [TIFF OMITTED] TP30JN04.011


where:
s = test compound concentration, mg/liter
G = volumetric gas flow rate, liters/hr
Keq = Henry's Law constant measured in the system, (mg/
liter gas)/(mg/liter liquid)
V = volume of liquid in the reactor, liters
X = biomass concentration (g MLVSS/liter)
K1 = first order biodegradation rate constant, liter/g 
MLVSS/hr

    Equation App. C-7 can be integrated to obtain the following 
equation:

[[Page 39390]]

[GRAPHIC] [TIFF OMITTED] TP30JN04.012


where:

Peakareat = the area of the non-speciated compound peak 
at time t,
Peakareao = the area of the non-speciated compound peak 
at the beginning of the run,
GKeq/V = contribution to the slope from stripping only, 
and
K1X = contribution to the slope from biodegradation.

    If ln(Peakarea) is plotted on the y axis and t is plotted on the 
x axis, the data should form a straight line with a slope that 
equals the negative of the terms in parenthesis on the right of 
Equation App. C-8 and the intercept of this line on the y axis 
equals ln (Peakareao).
    A discussion of Equation App. C-8 is provided in reference 9. 
This equation is used to analyze the two stripping runs, with and 
without biodegradation. Evaluate the slope for each non-speciated 
peak for both the run without biodegradation and the run with 
biodegradation.

    3.6 Henry's law constants. To evaluate the Henry's law constant 
for each unspeciated VOC, you obtain the slope for the run without 
biodegradation and then equate this slope (with a negative value) to 
-GKeq. The value of Keq is then equal to the 
product of the negative of the slope and V, divided by G.
    3.7 Biodegradation rate constant. To evaluate the first order 
biorate constant, use the slope for each non-speciated peak for the 
run without biodegradation and subtract the corresponding slope of 
the non-speciated peak with biodegradation. This difference equals 
K1X. The value of K1 that is determined in 
this manner is used to characterize the biodegradation rate under 
the conditions in the full-scale biodegradation unit that you are 
evaluating.
    3.8 Accuracy concerns. The non-speciated compound peak data may 
contain scatter that can adversely influence the data 
interpretation. In the case of significant data scatter for a 
specific compound that will limit the ability to determine the 
difference in slopes from the two runs, it is possible to use 
conventional statistics to estimate the accuracy of the difference 
in slopes. When it is not possible to demonstrate a significant 
difference in the slopes of the two runs for a non-speciated 
compound, the value of K1 is set to zero. A negative 
value of K1 is never used. If the specific compound of 
concern has a statistically significant negative value of 
K1, this can be an indication of the formation of the 
compound as a byproduct and is reported as an anomalous result. It 
is necessary to provide documentation of data and calculations.
    If the stripping rate constant is relatively large when compared 
to the biorate, it may be difficult to obtain an accurate evaluation 
of the first-order biorate constant. In these cases, either reducing 
the stripping rate constant by lowering the aeration rate, or 
increasing the biomass concentrations should be considered. If the 
aeration rate is changed, the equilibrium assumption will have to be 
verified again. Equilibrium conditions are typically more difficult 
to obtain at greater aeration rates, but lower aeration rates could 
result in difficulty in achieving equilibrium conditions due to 
poorer mixing.
    3.9 The concentration of each compound. The amount of each 
individual non-speciated organic compound is calculated by measuring 
the initial area of the chromatographic peak of the individual 
compound, Peakareao, the ratio of the peak area to the 
gas phase concentration, F, the SPME fiber partition factor, 
Kfiber, and the partition coefficient, Keq. 
The Peakareao is the intercept of the line with the y 
axis (plot of ln Peakarea vs. time). If automatic gas sampling is 
used for the analysis, a representative calibration of the gas 
chromatographic peak area and the gas phase concentration is 
required, and a correlation for the fiber partition factor is not 
used because the SPME method is not used. For complex chemicals with 
relatively poor biodegradation rates, it may be necessary to modify 
the procedure using multiple columns or detectors.

    The equation used for the SPME method is as follows:
    [GRAPHIC] [TIFF OMITTED] TP30JN04.013
    

 where:

CL = the concentration of the component in the water, 
(mg/L),
PA = the integrated peak area of the component in the gas 
chromatograph, (area counts),
Keq = the ratio of the concentration of the component in 
the headspace to the concentration of the component in the water, 
(mg/L per mg/L),
Kfiber = the ratio of the mass on the extraction fiber to 
the concentration of the component in the headspace, (mg per mg/L), 
and
F = the ratio of the peak area to the mass on the extraction fiber, 
(area counts/mg).

    The equation used for the automatic headspace sampling 
alternative is as follows:
[GRAPHIC] [TIFF OMITTED] TP30JN04.014

where the symbols are defined above, and Fc is the ratio of the peak 
area count to the concentration in the gas phase, (mg/L). This 
number depends on the sampling and analysis setup.
    3.10 SPME fiber partition correlation. If automatic gas sampling 
is used, it is not necessary to account for SPME fiber partition 
effects, but it is necessary to use gas chromatographic calibration 
factors for the compounds of interest. Reference 9 presents 
additional details on the use of gas chromatographic calibration 
factors and SPME fiber partition factors.
    The SPME fiber partition factor is obtained by preparing an 
aqueous solution or solutions with known compounds of varying 
volatility and chemical characteristics that are representative of 
the waste stream of concern. The detector peak areas and retention 
times are then obtained with the SPME method for these known 
compounds. The mass of compound is calculated from the area counts 
of the GC compound peak, and the concentration in the headspace is 
calculated from the Henry's law factor and the known liquid 
concentration. The fiber partition factor Kfiber is the 
ratio of the mass of compound to the concentration in the headspace 
at equilibrium with the aqueous solution. A correlation is then 
obtained between the value of Kfiber and the retention 
time of the detector response.
    The SPME fiber partition factor correlation for a series of 
petrochemical compounds that is provided in Figure 4 of reference 9 
can be used with verification of the correlation with a few 
compounds if the chemicals in that correlation are representative of 
the waste stream of concern. The fiber recovery of the compound is 
correlated with the volatility (aqueous Henry's law constant) as a 
result of the experimental measurements of the headspace 
concentrations by the fiber extraction method.
    If some characterization is available for the waste stream of 
concern, such as a compound identification of more than 25 percent 
of the major compounds present in the waste, it is recommended that 
selected members of these identified compounds are included in the 
measurements for the determination of the site-specific SPME fiber 
partition factor correlation.
    In some cases, after concluding the non-speciated method runs 
for the waste with and without biomass, the SPME partition factor 
correlation may appear to be inappropriate for the waste stream. 
Some of the reasons for this could include incorrect compound 
concentration for a known compound, incorrect concentration ratios 
of known compounds, or test data outside the applicable range of the 
correlation. When there are problems with the SPME partition factor 
correlation, the correlation may be improved without the need to 
rerun the non-speciated method runs for the waste with and without 
biomass.
    If, unlike the petroleum compound set evaluated in reference 9, 
you are unable to obtain a single correlation for use in 
interpreting the data that you obtain from this method, you should 
consider the use of two or more correlations with multiple 
correlations and multiple detectors/fiber types. A discussion of the 
methods used in this multiple correlation technique alternative is 
outside the scope of this discussion. This alternative of more than 
one correlation should not be used without supporting experimental 
investigations to verify the technical approach that you are using. 
The EPA Method 25D describes the use of two different types of gas

[[Page 39391]]

chromatograph detectors to more completely characterize the 
compounds in the waste. You may wish to consider the use of 
automatic direct headspace sampling in the case of difficulty with 
identifying adequate SPME correlations.
    3.11 Calculation of the total non-speciated compound 
concentration. The measured individual organic compound 
concentrations are summed to obtain the total non-speciated compound 
concentration. Certain compounds may be excluded from this total. 
Examples of components that may be excluded from the total summation 
procedures are the following:
     Components that are present in the vapor phase in 
concentrations too low to measure.
     Components that are identified and have specific 
regulatory exclusion.
     Components that have gas chromatographic retention 
times that are substantially greater than can be considered 
characteristic of volatile components.
    3.12 Calculation of fe and fbio for each compound. The site 
specific biodegradation unit characteristics are used with the 
measured values of the compound Henry's law value and the 
biodegradation first order rate constant to estimate fe 
and fbio for each compound.
    3.13 Calculation of the overall fe and fbio for the total 
volatile waste components. The individual organic compound 
concentrations are used with individual values of fe and 
fbio to obtain the total biological removal and the total 
air emission removal from the treatment unit. In the case of an 
ideal stirred tank reactor, the amount of each component entering 
the reactor is calculated by multiplying the flow rate of the waste 
(m3/s) by the concentration (g/m3) to obtain 
the individual loading rate (g/s). For each compound that is not 
excluded, the individual loading is summed to obtain the total 
loading. The overall biological removal is the sum of the products 
of the individual loading rate (g/s) and the individual value of 
fbio. The overall air removal is the sum of the products 
of the individual loading rates (g/s) and the individual values of 
fe. The overall fbio value is the ratio of the 
overall biological removal to the total loading. The overall 
fe value is the ratio of the overall air emissions loss 
to the total loading.
    Reference 9 presents examples of the use of the above procedures 
to evaluate the fraction biodegraded for two types of biotreatment 
units.
    3.14 Computer assisted calculations. It is possible to use 
computer assisted data acquisition and data analysis in order to 
reduce the extensive labor requirements to perform the above 
procedures manually. You may use either manual methods, electronic 
spreadsheets, or compiled programs that can directly import the gas 
chromatographic computer files. Present the results for each non-
speciated component, the summary of the weighted average 
fbio using each relevant component, and supporting 
quality assurance information. The slope and intercept of the 
correlation curve, the correlation coefficient, and the number of 
data points used for the correlation are examples of supporting 
quality assurance information.
    4. Quality Control/Quality Assurance (QA/QC). A QA/QC plan 
outlining the procedures used to determine the biodegradation rate 
constants shall be prepared and a copy maintained at the source. The 
plan should include, but may not be limited to:
    1. A description of the apparatus used (e.g., size, volume, 
method of supplying air or oxygen, mixing, and sampling procedures) 
including a simplified schematic drawing.
    2. A description of how biomass was sampled from the activated 
sludge unit.
    3. A description of how biomass was held prior to testing (age, 
etc.).
    4. A description of what conditions (DO, gas-liquid equilibrium, 
temperature, etc.) are important, what the target values are, how 
the factors were controlled, and how well they were controlled.
    5. A description of how the experiment was conducted, including 
preparation of solutions, dilution procedures, sampling procedures, 
monitoring of conditions, etc.
    6. A description of the analytical instrumentation used, how the 
instruments were calibrated, and a summary of the precision for that 
equipment.
    7. A description of the analytical procedures used. If 
appropriate, reference to an ASTM, EPA or other procedure may be 
used. Otherwise, describe how the procedure is done, what is done to 
measure precision, accuracy, recovery, etc., as appropriate.
    8. A description of how data are captured, recorded, and stored.
    9. A description of the equations used and their solutions, 
including a reference to any software used for calculations and/or 
curve-fitting.
    3. Appendix C is amended by revising section III.E to read as 
follows:

E. Multiple Zone Concentration Measurements (Procedure 5)

    Procedure 5 is the concentration measurement method that can be 
used to determine the fbio for units that are not 
thoroughly mixed and thus have multiple zones of mixing. As with the 
other procedures, proper determination of fbio must be 
made on a system as it would exist under the rule. For purposes of 
this calculation, the biological unit must be divided \1\ into zones 
with uniform characteristics within each zone. The number of zones 
that is used depends on the complexity of the unit. Reference 8, ``A 
Technical Support Document for the Evaluation of Aerobic Biological 
Treatment Units with Multiple Mixing Zones,'' is a source for 
further information concerning how to determine the number of zones 
that should be used for evaluating your unit. The following 
information on the biological unit must be available to use this 
procedure: (1) Basic unit variables such as inlet and recycle 
wastewater flow rates, type of agitation, and operating conditions; 
(2) measured representative organic compound concentrations in each 
zone and the inlet and outlet; and (3) estimated mass transfer 
coefficients for each zone.
---------------------------------------------------------------------------

    \1\ This is a mathematical division of the actual unit; not 
addition of physical barriers.
---------------------------------------------------------------------------

    The estimated mass transfer coefficient for each compound in 
each zone is obtained from Form II using the characteristics of each 
zone. A computer model may be used. If the Water7 model or the most 
recent update to this model is used, then use Form II-A to calculate 
KL. The TOXCHEM or BASTE model may also be used to calculate KL for 
the biological treatment unit, with the stipulations listed in 
procedure 304B. Compound concentration measurements for each zone 
are used in Form XIII to calculate the fbio. A copy of 
Form XIII is completed for each of the compounds of concern treated 
in the biological unit.
    4. Appendix C is amended by revising equation C-7 in section IV 
to read as follows:
    IV. Calculation of fbio
* * * * *
[GRAPHIC] [TIFF OMITTED] TP30JN04.015

where:

M = compound specific average mass flow rate of the organic 
compounds in the wastewater (Mg/Yr)
n = number of organic compounds in the wastewater

* * * * *
    5. Appendix C is amended by revising the references to read as 
follows:

    1. Rajagopalan, S., R. van Compernolle, C.L. Meyer, M.L. Cano, 
and P.T. Sun. ``Comparison of methods for determining biodegradation 
kinetics of volatile organic compounds.'' Wat. Env. Res. 70: 291-
298.
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Federation 72nd Annual Conference and Exposition, New Orleans, LA, 
October 9-13.

[FR Doc. 04-14826 Filed 6-29-04; 8:45 am]
BILLING CODE 6560-50-P