&EPA
United States
Environmental Protection
Agency
Risk Reduction Engineering
Laboratory
Cincinnati, OH 45268
EPA/600/2-88/062
Apr. 1989
Research and Development
Toxicity Reduction
Evaluation Protocol for
Municipal Wastewater
Treatment Plants
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EPA/600/2-88/062
April 1989
Toxtcity Reduction Evaluation Protocol
for Municipal
Wastewater Treatment Plants
by
John A. Botts
Jonathan W. Braswell
Jaya Zyman
Engineering-Science, Inc.
Fairfax, Virginia 22030
William L. Goodfellow
EA Engineering, Science and Technology
Sparks, Maryland 21152
Samuel B. Moore
Burlington Research, Inc.
Burlington, North Carolina 27215
Contract No. 68-03-3431
Project Officer
Dolloff F. Bishop
Treatment Assessment Branch
Risk Reduction Engineering Laboratory
Cincinnati, Ohio 45268
•
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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Disclaimer
This material has been funded wholly or in part by the United States Environmental
Protection Agency under contract 68-03-3431 to Engineering-Science, Inc. It has
been subject to the Agency's review and it has been approved for publication as an
EPA document. Mention of trade names or commercial products does not constitute
endorsement or recommendation.
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Foreword
Today's rapidly developing and changing technologies and industrial products and
practices frequently carry with them the increased generation of materials that, if
improperly dealt with, can threaten both public health and the environment. The U.S.
Environmental Protection Agency is charged by Congress with protecting the nation's
land, air, and water resources. Under a mandate of national environmental laws, the
agency strives to formulate and implement actions leading to a compatible balance
between human activities and the ability of natural systems to support and nurture life.
These laws direct the EPA to perform research to define our environmental problems,
measure the impacts, and search for solutions.
The Risk Reduction Engineering Laboratory is responsible for planning, implementing,
and managing research, development, and demonstration programs to provide an
authoritative, defensible engineering basis in support of the policies, programs, and
regulations of the EPA with respect to drinking water, wastewater, pesticides, toxic
substances, solid and hazardous wastes, and Superfund-related activities. This
publication is one of the products of that research and provides a vital communication
link between the researcher and the user community.
This guidance document on municipal toxicity reduction evaluations (TRE) was
prepared to provide technical support for water quality-based toxicity control in the
National Pollution Discharge Elimination System (NPDES). It was designed to provide
guidance for conducting TRE assessments at municipal wastewater treatment plants.
This guidance document describes the state-of-the-art procedures and the general
decision-making process for conducting municipal TREs.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
in
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Abstract
This document presents a generalized protocol for conducting Toxicity Reduction
Evaluations (TREs) at municipal wastewater treatment plants (WWTPs). This protocol
is designed to provide guidance to municipalities in preparing TRE plans, evaluating the
information generated during TREs, and developing a technical basis for the selection
and implementation of toxicity control methods. A TRE involves an evaluation of the
municipal WWTP performance; an identification of the specific toxicants causing
effluent toxicity; a review of the pretreatment and local limits programs; a
characterization of the nature, variability and sources of toxicity; and the evaluation,
selection and implementation of the toxicity control options.
Because of the broad scope of this protocol, it is to be expected that site specific
considerations may to some extent warrant modifications and tailoring of the protocol
approach for a given facility. The protocol has been developed based on current
research and experience. TRE methods and procedures will be updated and refined
based on the results of ongoing research and case studies.
IV
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Contents
Page
Foreword , iii
Abstract iv.
Figures . jx
Tables ; . x
Abbreviations and Symbols xi
Acknowledgements , xiii
1. Introduction 1-1
Background 1-1
TRE Definition and Objectives . . . M-1-
Components of the Municipal TRE Protocol 1-2.
Information and Data Acquisition 1-2
POTW Performance Evaluation : 1-2
Toxicity Identification Evaluations 1-2
Toxicity Source Evaluation (Tier I) 1-2
Toxicity Source Evaluation (Tier II) 1-2
POTW In-Plant Control Evaluation 1-2
Toxicity Control Selection 1-4
Toxicity Control Implementation 1-4
Limitations of the Protocol 1-4
Organization of the Document 1-4
2. Information and Data Acquisition 2-1
Introduction 2-1
POTW Design and Operations Data 2-1
Pretreatment Program Data 2-1
3. POTW Performance Evaluation 3-1
Introduction 3-1
Operations and Performance Review 3-1
Primary Sedimentation 3-1
Aerobic Biological Treatment 3-1
Organic Loading 3-3
Oxygen Requirements 3-3
Mean Cell Residence Time 3-3
Secondary Clarification 3-3
Process Sidestreams and Wastewater Bypasses 3-4
Disinfection 3-4
Optional TIE Phase I Tests 3-4
Conventional Wastewater Treatability Testing 3-5
Coagulation and Precipitation 3-6
Sedimentation 3-6
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Contents (continued)
Page
Activated Sludge 3-6
Granular Media Filtration . . 3-6
Activated Carbon Adsorption 3-6
4. Toxicity Identification Evaluation 4-1
Introduction 4-1
Toxicity Test Procedures 4-1
Toxicity Characterization and Toxicant
Identification Procedures 4-2
Phase I - Toxicity Characterization 4-3
Phase II - Causative Toxicant Identification ...... I........ 4-3
Phase III - Causative Toxicant Confirmation . . 4-3
5. Toxicity Source Evaluation - Tier I 5-1
Introduction . 5-1
Sampling Location 5-1
Chemical-Specific Investigation . . 5-2
Pretreatment Program Review 5-3
Refractory Toxicity Assessment 5-3
Biomass Toxicity Measurement 5-4
Sample Collection 5-6
Sample Characterization and Preparation 5-6
Preparation of Batch Test Mixtures . 5-7
Performance of Batch Tests 5-7
Toxicity Measurement 5-8
Data Evaluation 5-8
RTA Conclusions 5-9
6. Toxicity Source Evaluation - Tier II 6-1
Introduction 6-1
Refractory Toxicity Assessment 6-1
Biomass Toxicity Measurement 6-1
Sample Collection, Characterization, and Preparation 6-1
Preparation of Batch Test Mixtures 6-1
Performance of Batch Tests 6-2
Inhibition Testing (Optional) 6-4
Toxicity Analysis 6-5
Phase I - Toxicity Characterization 6-5
Data Evaluation 6-5
Pretreatment Control Evaluation 6-7
7. POTW In-Plant Control Evaluation 7-1
Introduction 7-1
Selection of Treatment Options for Testing . 7-1
VI
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Contents (continued)
Page
Process Enhancement 7-2
Biological Process Control 7-2
Chemical Addition .:.............. 7-2
Additional Treatment 7.3
Equalization 7-3
Instrumentation/Control . . . 7-4
Advance Wastewater Treatment . 7-4
Treatability Testing 7.4
Activated Sludge 7-4
Coagulation/Flocculation 7.4
Sedimentation 7-4
Granular Media Filtration 7-4
Granular Activated Carbon 7.4
8. Toxicity Control Selection g - 1
Introduction 8-1
Evaluation of Control Options 8-1
9. Toxicity Control Implementation 9-1
Implementation : . . . 9-1
Follow Up Monitoring 9-1
10. Quality Assurance/Quality Control 10-1
Introduction 10-1
Sampling Collection and Preservation 10-1
Chain-of-Custody . 10-1
Analytical QA/QC 10-2
Toxicity Identification Evaluation 10-2
, Refractory Toxicity Assessment and Treatability
Tests 10-3
Chemical Analyses 10-3
Equipment Maintenance 10-3
Documentation and Reporting of Data 10-4
Corrective Action . 10-4
11. Healtb and Safety 1 1 -1
Ove|//ew 11-1
Sample Collection and Handling . 11-1
Analytical Methods 11-1
Toxicity Identification Procedures (TIE) .......: 11-1
Refractory Toxicity Assessment and Treatability
Tests ; 11-2
Chemical Analyses 1 1 - 2
GerieraX Precautions . 1 1 - 2
VII
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Contents (continued)
12.
13.
Facilities and Equipment
Introduction
Toxicity Identification Evaluations
Refractory Toxicity Assessment and Treatability
Tests
General Analytical Laboratory Equipment
Sample Collection and Handling
Introduction
Sampling Location
POTW Sampling
Sewer Discharge Sampling ,
Page
1 2-1
1 2-1
12-1
1 2-1
1 2-2
13-1
1 3-1
1 3-1
1 3-1
1 3-2
References 14-1
Bibliography 15-1
Appendices
A. Case Histories A - 1
B. Pretreatment Program Review B - 1
VIII
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Figures
Number
1-1
3-1
4-1
5-1
6-1
7-1
Page
TRE Flow Diagram for Municipal Wastewater Treatment
Plant 1-3
Plant Performance Evaluation 3-2
Toxicity Identification Evaluation 4-2
Tier I: Toxicity Source Evaluation 5-2
Tier II: Toxicity Source Evaluation (Source Ranking/
Pretreatment Evaluation) 6-2
POTW In-Plant Control Evaluation 7-1
IX
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Tables
Number Page
2-1 POTW Design and Operations Data 2-2
2-2 Pretreatment Program Data 2-3
5-1 Tier I - Refractory Toxicity Assessment 5-5
5-2 Synthetic Wastewater Composition 5-7
6-1 Tier II - Refractory Toxicity Assessment 6-3
7-1 POTW In-Plant Control Technologies for Categories
of Toxic Compounds '. . 7-3
8-1 Comparison of Selection Criteria for Toxicity
Control Operations 8-2
B-1 PPR Data Sheet B-2
B-2 Data Sheet for Regression Analysis B-3
B-3 Summary of the PPR Chemical Optimization Procedure B-4
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Abbreviations and Symbols
AA
ASTM
ATP
BOD
BOD5
C. dubia
CERCLA
CFR
COG
COD
Cr
CSO
Cu
DMR
DO
EC50
EDTA
EP
EPA
F/M
g/i
GAG
GC
H&S
HNO3
HPLC
ICP
IU
IWS
LC50
MCRT
mg/l
MLSS
• Atomic absorption
• American Society for Testing and Materials
• Adenosine triphosphate
• Biochemical oxygen demand
5-day biochemical oxygen demand
Ceriodaphnia dubia
Comprehensive Environmental Response, Compensation
and Liability Act
Code of Federal Register
Chain-of-Custody
Chemical oxygen demand
Chromium
Combined sewer overflow
Copper
Discharge monitoring report
Dissolved oxygen
Effective concentration causing a 50% effect in the test species
Chelating agent
Extraction procedure
Environmental Protection Agency
Food to microorganism ratio ;
Grams per liter
Granular activated carbon
Gas chromatography
Health and Safety
Nitric acid
High pressure liquid chromatography
Inductively coupled plasma spectrometry
Industrial user
Industrial waste survey
Lethal concentration causing a 50% mortality in exposed test
organisms
Mean cell residence time
Milligrams per liter
Mixed liquor suspended solids
XI
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Abbreviations and Symbols (continued)
MLVSS
MS
MSDS
NPDES
02
OSHA
OUR
PAC
PACT
pH
POTW
PPE
PPR
QA/QC
RAS
RBC
RCRA
RTA
SARA
SBOD5
SCOD
SIC
SOR
SOUR
SPE
SRT
SS
SSUR
TBTO
TCIP
TCLP
IDS
TIE
TKN
TP
TRC
TRE
TSDF
TSS
TTO
WWTP
xg
Zn
ZSV
- Mixed liquor volatile suspended solids
- Mass spectrometry
- Material safety data sheet
- National Pollutant Discharge Elimination System
- Oxygen
- Occupational Safety and Health Administration
- Oxygen uptake rate
- Powdered activated carbon
- Powdered activated carbon treatment
- Negative logarithm of hydrogen ion concentration or hydrogen
potential
- Publicly owned treatment works
- Plant performance evaluation
- Pretreatment program review
- Quality assurance/quality control
- Return activated sludge
- Rotating biological contactor
- Resource Conservation and Recovery Act
- Refractory toxicity assessment
- Superfund Amendments and Reauthorization Act
- Five-day soluble biochemical oxygen demand
- Soluble chemical oxygen demand
- Standard industrial code
- Surface overflow rate
- Specific oxygen uptake rate
- Solid phase extraction
- Sludge retention time or sludge age
- Suspended Solids
- Specific substrate utilization rate
- Total brominated toxic organics
- Toxics control implementation plan
- Toxicity characteristic leaching procedure
- Total dissolved solids
- Toxicity identification evaluation
- Total kjeldahl nitrogen
- Total phosphorus
- Total residual chlorine
- Toxicity reduction evaluation
- Treatment, storage, and disposal facility
- Total suspended solids
- Total toxic organics
- Wastewater treatment plant
- Times gravity
- Zinc
- Zone settling velocity
XII
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p
Acknowledgements
The TRE protocol was a cooperative effort by the EPA and three consulting firms:
Engineering-Science, EA Engineering Science and Technology, and Burlington
Research. Individuals listed below are gratefully acknowledged for their technical
assistance.
Environmental Protection Agency ;
Dolloff Bishop - Risk Reduction Engineering Laboratory, Cincinnati
(formerly Water Engineering Research Laboratory)
John Cannell - Permits Division, Washington, D.C.
Linda Anderson-Carnahan - Region IV, Water Management Division, Atlanta
Kenneth Dostal - Risk Reduction Engineering Laboratory, Cincinnati
P
Additional Acknowledgements
Elizabeth C. Sullivan - CH2M Hill, Reston, Virginia
Mick Degraeve and James Fava - Battelle, Columbus Division
XIII
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Section 1
Introduction
Background
The Toxicity Reduction Evaluation Protocol for
Municipal Wastewater Treatment Plants provides a
systematic framework for conducting a toxicity
reduction evaluation (TRE) and a description of the
available methods and procedures, which experience
to date have shown to be most useful. This protocol
is designed for use by municipal facilities [Publicly
Owned Treatment Works (POTW)] which are
conducting a TRE to meet NPDES whole effluent
toxicity permit limits. It presents methods and
procedures that will be useful for: 1) the design of a
TRE, 2) the development and review of a TRE plan,
3) the evaluation of the results and data generated
during the TRE, and 4) the development of a sound
scientific and engineering basis for the selection and
implementation of a toxicity control method.
This document supports the integrated toxics control
strategy using whole effluent toxicity and pollutant
specific limits described in previous EPA guidance,
notably, the Technical Support Document for Water
Quality-based Toxics Control (1985a) and The
Permit Writer's Guide to Water Quality-based
Permitting for Toxic Pollutants (1987b). It has become
well recognized that while POTWs may achieve
effluent limits for conventional pollutants, pass-
through of effluent toxicity, volatilization, and
contamination of sewage sludges can still occur. The
focus of this protocol is on the reduction of toxicity in
municipal wastewater treatment plant effluents. It is
the responsibility of the POTW to conduct a toxicity
reduction evaluation in order to achieve the TRE
objectives and meet the applicable NPDES permit
limits. The regulatory authority will review the TRE
plan and carefully monitor the progress of the TRE,
providing direction as needed.
This municipal TRE protocol provides guidance for
municipalities and their consultants on how to
conduct a TRE at a POTW. The methods and
decision points which comprise a TRE are described
in the context of an overall generalized approach.
Because the regulatory issues and treatment
operations are unique for each POTW, not all
elements of this protocol will apply to every case, and
each municipality will need to develop its own site-
specific TRE plan. The protocol has been developed
based on the research and experience to date. The
methods and procedures described will be updated
and refined based on the results of on-going
research and case studies.
TRE Definitions and Objectives
EPA's Permit Writer's Guide to Water Quality-Based
Permitting for Toxic Pollutants (1987) defines a TRE
as "a step-wise process which combines toxicity
testing and analysis of the physical and chemical
characteristics of causative toxicants to zero in on the
toxicants causing effluent toxicity and/or on treatment
methods which will reduce the effluent toxicity."
Because a TRE is conducted in a tiered approach,
judgement is required in selecting the appropriate
steps for characterizing the causative toxicants and
for evaluating options for controlling effluent toxicity.
To support TRE studies, EPA has developed a
guidance manual entitled "Methods for Aquatic
Toxicity Identification Evaluations (Mount and
Anderson-Carnahan, (1988a) which describes
procedures for identifying the toxicants causing
effluent toxicity. The TIE procedures are a basic
component of the municipal TRE protocol and should
be carefully studied prior to their application in
municipal TREs. In addition EPA has developed a
general protocol for conducting industrial TREs (Fava,
etal., 1988).
The overall objectives to be achieved in a municipal
TRE are to:
• Evaluate the operation and performance of the
POTW to identify and correct treatment
deficiencies causing effluent toxicity;
• Identify the toxic compounds causing effluent
toxicity;
1-1
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• Trace the effluent toxicants and/or toxicity to
their sources; and
• Evaluate, select and implement toxicity reduction
methods and technologies to control effluent
toxicity.
Components of the Municipal TRE
Protocol
The overall flowchart for a TRE program is illustrated
in Rgure 1-1. A brief description of each major TRE
component is presented as follows.
Information and Data Acquisition
The first step in a TRE is the collection of all
information and analytical data pertaining to effluent
toxicity. This information includes data on the
operation and performance of the POTW such as
plant design criteria and discharge monitoring reports,
and data from the POTW's pretreatment program
such as industrial waste survey applications and local
limits compliance reports. The POTW performance
data are evaluated in the second stage of the TRE as
described below. The pretreatment program data are
used in the latter stages of the TRE to assist in
tracing the influent sources of toxicity and/or toxics
which are contributing to the POTW effluent toxicity.
POTW Performance Evaluation
POTW operating and performance data can be
evaluated to indicate possible in-plant sources of
toxicity or operational deficiencies that may be
allowing toxicity pass-through. In parallel with this
evaluation an optional toxicity characterization test
(TIE Phase I) can be performed to indicate the
presence of in-plant toxicants caused by incomplete
treatment (e.g., ammonia) or routine operating
practices (e.g., chlorine). If a treatment deficiency or
operating practice is causing effluent toxicity,
treatability studies should be conducted to evaluate
treatment modifications for reducing the toxicity. If
plant performance is not a principal cause of the
toxicity problem or treatment options do not reduce
the toxicity, the TRE proceeds to TIE testing.
Toxicity Identification Evaluations
TIE procedures utilize aquatic toxicity tests of the
effluent following bench top treatment steps to
characterize the classes of toxicants causing effluent
toxicity. Subsequent effluent manipulations in
conjunction with chemical analyses are used to
identify and confirm the specific toxicity-causing
compounds.
The TIE protocol is performed in three phases:
toxicity characterization (Phase I), toxicant
identification (Phase II) and toxicant confirmation
(Phase III). In some situations POTW pretreatment
program data may help in identifying the effluent
toxicants. If the specific effluent toxicants are
identified, a control method such as local
pretreatment limits may be implemented. If additional
data are required to determine the nature and
sources of the toxicants, a toxicity source evaluation
is conducted.
Toxicity Source Evaluation (Tier I)
The initial stage of a toxicity source evaluation
involves sampling the effluent of sewer dischargers or
sewer lines and analyzing the wastewaters for toxics
and/or toxicity. Because the toxicity of the POTW
influent wastewater is not necessarily the same
toxicity that is observed in the POTW effluent, sewer
samples are treated in a simulation of the POTW's
biological treatment process prior to toxicity analysis
to account for the toxicity removal provided by the
POTW.
The choice of chemical-specific analyses or toxicity
tests for source tracking will depend on the quality of
the TIE results. Chemical-specific tracking is
recommended where the specific toxicants have been
identified and can be readily traced to the responsible
sewer dischargers. Toxicity tracking is required where
TIE data on specific toxicants are not definitive.
If Tier I testing is successful in locating the sources
that are contributing the POTW effluent toxicants, a
toxicity control method such as local limits can be
developed and implemented. If additional information
on toxic indirect discharges is needed, further toxicity
source testing is conducted.
Toxicity Source Evaluation (Tier II)
A Tier II evaluation is performed to confirm the
suspected sources of toxicity identified in Tier I. Tier
II testing involves testing the toxicity of selected
sewer dischargers following simulated POTW
treatment as in Tier I. Additional characterization
steps are used in Tier II to determine the relative
amount and the types of toxicity contributed by each
discharger. Tier II information is used to rank the
indirect dischargers with respect to their toxicity/toxics
loading and to evaluate local limits as a toxicity
control option.
POTW In-Plant Control Evaluation
A POTW control evaluation is conducted in parallel
with the Tier II assessment to evaluate in-plant
options for reducing effluent toxicity. If in-plant
control appears to be a feasible approach, treatability
testing is used to evaluate methods for optimizing
existing treatment processes and to assess options
for additional treatment.
1-2
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P
NPDESTRE Permit Conditions
Requirements/Recommendations
_L
Information and Data Acquisition
Pretreatment Program Review, POTW Design
and Operating Review
POTW Performance I
Evaluation (Figure 3-1 )^~"
Toxicity Identification
Evaluation (Figure 4-1)
Additional
Information
Required
Yes
P
Toxicity Source Evaluation-
Tier I: (Figure 5-1)
Additional
Information
Required
Yes
Toxicity Source Evaluation— Tier I
Source Ranking/Pretreatment
Evaluation (Figure 6-1)
Initial Phase I
Toxicity Characterization
Yes
Conventional Pollutant
Treatability Tests
Yes
Toxicity
Pass-Through
or Treatment
Inhibition
No
No
POTWIn-Plant
Control Evaluation
(Figure 7-1 )
Toxicity Control
Selection
No
Toxicity Control
Implementation and
Follow-Up Monitoring
Figure 1-1. THE flow diagram for municipal wastewater treatment plant.
1-3
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Toxicity Control Selection
Using the results of the TIE testing, the Tier I and Tier
II toxicity source evaluation and the POTW treatability
testing, alternatives for effluent toxicity reduction are
evaluated and the most feasible option(s) is selected
for implementation. The choice of a control option(s)
is based on several technical and cost criteria.
Toxicity Control Implementation
The toxicity control method or technology is
implemented and follow-up monitoring is conducted to
ensure that the control method achieves the TRE
objectives and meets permit limits.
Limitations of the Protocol
This document addresses the protocol for evaluating
and implementing methods for reduction of whole
effluent toxicity. Because regulations concerning the
transfer of toxics to sludge and air in POTWs are still
under development, specific procedures for sludge
and air toxics reduction are not discussed. The reader
may consult EPA's Guidance Document for Writing
Permit Requirements for Municipal Sewage Sludge
(1988a) regarding permit conditions for sludge.
The municipal TRE protocol was developed based on
the results and findings of several TRE and TIE
studies. Some of the procedures used in these
studies, especially tools for toxicity source
evaluations, have not been widely used and will
therefore require further refinement as more
experience is gained. Additionally, the feasibility and
effectiveness of in-plant and pretreatment toxicity
control options have not been well documented and
additional experience in this area is needed.
Organization of the Document
This document is organized according to the
components of the TRE protocol flowchart (Figure 1-
1). The section headings are as follows:
Section 2 Information and Data Acquisition
Section 3 POTW Performance Evaluation
Section 4 Toxicity Identification Evaluation
Section 5 Toxicity Source Evaluation (Tier I)
Section 6 Toxicity Source Evaluation (Tier II)
Section 7 POTW In-Plant Control Evaluation
Section 8 Toxicity Control Selection
Section 9 Toxicity Control Implementation
Sections 10 through 13 describe the TRE
requirements for quality assurance/quality control,
health and safety, facilities and equipment, and
sample collection and handling. In Appendix A case
examples of municipal TREs are discussed with
respect to the study approach, important findings and
problems encountered. Appendix B provides a
detailed description of selected TRE procedures.
1-4
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Section 2
Information and Data Acquisition
Introduction
The first step in a TRE is the collection of all
information and data that may relate to effluent
toxicity and that might prove useful in conducting the
TRE. This information is generally divided into two
main categories: POTW treatment system data and
pretreatment program data. In addition to historical
effluent toxicity data, the pertinent POTW information
includes data on the treatment plant's design
capabilities, treatment performance, and operation
and maintenance practices. The appropriate
pretreatment program information consists of
industrial waste survey data, and pretreatment
monitoring and compliance reports.
A summary of existing information required for a TRE
is provided in the following subsections. It is important
to emphasize that drawing preliminary conclusions
based on this initial information can' be misleading.
Thus, the compiled data should be reserved for use
as indicated in subsequent steps of the TRE protocol.
POTW Design and Operations Data
The primary objective in retrieving POTW design and
operations information is to establish a data base to
be used in the POTW Performance Evaluation
(Section 3). This information can indicate possible
in-plant sources of toxicity or operational problems
that might be contributing to treatment interferences
or toxicity pass-through. In addition, the POTW data
will be useful in evaluating and selecting ih-plaht-
toxicity control options (Section 7).
The pertinent POTW design and operations data to
be gathered include treatment system design
information and the data routinely collected for
NPDES discharge monitoring reports (DMRs) and for
process control. A list of useful POTW data is,
provided in Table 2-1.
Pretreatment Program Data
The POTW pretreatment program data are used
throughout the TRE. These data are reviewed in the
Toxicity Identification Evaluation (Section 4) to assist
in characterizing and identifying the effluent toxicants,
and they are evaluated in the Toxicity Source
Evaluation (Section 5) to aid in locating the influent
sources of toxicity.
The appropriate pretreatment program information
includes the data on the industrial users (lUs) of the
POTW (i.e., industrial manufacturers, RCRA waste
disposers, and CERCLA dischargers) and the toxic
pollutant data on the POTW wastestreams. A list of
suggested pretreatment data is shown in Table 2-2.
2-1
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Table 2-1. POTW Design and Operations Data
1, NPDES permit requirements
a. Effluent limitations
b. Special conditions
c. Monitoring data and compliance history
2. POTW design criteria
a. Hydraulic loading capacities
b. Pollutant loading capacities
c. Biodegradation kinetics calculations/assumptions
3, Influent and effluent conventional pollutant data
a. Biochemical oxygen demand
b. Chemical oxygen demand (COD)
c. Suspended solids (SS)
d. Ammonia
e. Residual chlorine
f. pH
4, Process control data
a. Primary sedimentation - hydraulic loading capacity and BOD and SS removal
b. Activated sludge - Food-to-microorganism (F/M) ratio, mean cell residence time (MCRT), mixed liquor suspended
solids (MLSS), sludge yield, and BOD and COD removal
c. Secondary clarification - hydraulic and solids loading capacity, sludge volume index and sludge blanket depth
5. Operations information
a. Operating logs
b. Standard operating procedures
c. Operations and maintenance practices
6. Process sidestream characterization data
a. Sludge processing sidestreams
b. Tertiary filter backwash
c. Cooling water
7. Combined sewer overflow (CSO) bypass data
a. Frequency
b. Volume
8. Chemical coagulant usage for wastewater treatment and sludge processing
a. Polymer
b. Ferric chloride
c. Alum
9. RCRA reports [if POTW is considered a hazardous waste treatment, storage and disposal facility (TSDF)]
2-2
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Table 2-2. Pretreatment Program Data
1.
P
POTW influent and effluent characterization data
a. Toxicity
b. Priority pollutants
c. Hazardous pollutants
d. SARA 313 pollutants
e. Other chemical-specific monitoring results
Sewage residuals (i.e., raw, digested, thickened and dewatered sludge and incinerator ash) characterization data
a. EP toxicity
b. Toxicity Characteristic Leaching Procedure (TCLP)
c. Chemical analysis
Industrial waste survey (IWS)
a. Information on IDs with categorical standards or local limits and other significant non-categorical IDs
(i) number of lUs
(ii) discharge flow
b. Standard Industrial Classification (SIC) code
c. Wastewater flow
d. Types and concentrations of pollutants in the discharge
e. Products manufactured
f. Description of pretreatment facilities and operating practices
Annual pretreatment program report
a. Schematic of sewer collection system
b. POTW monitoring data
(i) discharge characterization data
(ii) spill prevention and control procedures
(iii) hazardous waste generation
c. ID self-monitoring data
(i) description of operations
(ii) flow measurements
(iii) discharge characterization data
(iv) notice of slug loading
(v) compliance schedule (if out of compliance)
Technically based local limits compliance reports
Waste hauler monitoring data and manifests
RCRA reports [if the POTW is considered a hazardous waste treatment, storage and disposal facility (TSDF)]
a. Hazardous waste manifests
b. Operating record
c. Biennial report
d. Unmanifested waste report
CERCLA reports (if the POTW accepts wastes from a superfund site)
a. Preliminary assessment
b. Site investigations
c. Remedial investigations
d. Feasibility studies
e. CERCLA decision documents
Evidence of POTW treatment interferences (i.e., biological process inhibition)
2-3
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Section 3
POTW Performance Evaluation
introduction
POTW treatment deficiencies such as poor
conventional pollutant removal can have the effect of
increasing effluent toxicity. Prior to conducting
effluent toxicity characterization, an evaluation of the
POTW operations and performance should be made
to identify and correct treatment deficiencies that may
be responsible for all or part of the effluent toxicity. A
POTW performance evaluation (PPE) can be
conducted to indicate conventional pollutant treatment
deficiencies that may be causing toxicity and to
evaluate improvements in operations and treatment
that may eliminate in-plant sources of toxicity. The
flowchart for conducting a PPE is presented in Figure
3-1 .
The PPE involves a review of the major treatment unit
processes (e.g., primary sedimentation, activated
sludge and secondary clarification) using wastewater
characterization data and process operations
information. Additionally, an optional TIE Phase I
analysis (see Section 4) can be performed to indicate
the presence of effluent toxicants caused by
incomplete treatment (e.g., ammonia) or routine
operating practices (e.g., chlorine). Based on the
process review results and the Phase I data, options
for improving operations and performance are
selected and evaluated in treatability studies. If
treatability tests are successful in identifying the
necessary options for improving conventional
pollutant treatment and for reducing effluent toxicity,
the THE proceeds to the selection and
implementation of those options (Sections 8 and 9).
If, however, the treatment alternatives do not reduce
effluent toxicity to acceptable levels, further effluent
toxicity characterization is required using the TIE
procedures discussed in Section 4.
Operations and Performance Review
The operations and performance review involves the
evaluation of the major POTW unit processes using
the information described in Table 2-1. This review
focuses on the secondary treatment system, because
secondary treatment is responsible for removing the
majority of the conventional and toxic pollutants from
municipal wastewater. Deficiencies in this system are
more likely to result in incomplete treatment of
wastewater toxicity. Other unit processes to be
evaluated include primary sedimentation and
disinfection. Particular attention is paid to chlorine
disinfection because residual chlorine is highly toxic
to aquatic life.
Procedures for evaluating and improving POTW
operations and performance are described in EPA's
"Handbook on Improving POTW Performance Using
the Composite Correction Approach" (1984). The
composite correction approach utilizes a point system
to quantify process performance and to indicate
which treatment units need improvement.
Primary Sedimentation
Primary treatment processes are designed to reduce
the loading of suspended solids (SS), 5-day
biochemical oxygen demand (BODs) and chemical
oxygen demand (COD) on the secondary treatment
system. Toxics removal can also occur during primary
sedimentation from the settling of insoluble or
particulate toxic wastewater constituents. Optimal
removal of both toxic and conventional pollutants in
primary sedimentation will ultimately reduce the
amount of material passing through the biological
treatment process.
Primary clarifier performance can be evaluated by
comparing surface overflow rate (SOR), which is the
average daily flow divided by the clarifier surface
area, to the expected BOD5 removal. A clarifier
operating at an SOR of less than 25 m3/m2/day (600
gpd/sq ft) should remove 35 to 45 percent of the
influent BODs. A clarifier operating at an SOR of 25
to 40 m3/m2/day (600-1,000 gpd/sq ft) should
remove 25 to 35 percent of the influent BODs
(USEPA, 1984). In most cases COD removal
performance will be comparable to the BOD removal
performance.
Aerobic Biological Treatment
Aerobic biological treatment is a critical process in a
POTW, because it is the process that converts
organic matter to settleable microorganisms. Toxics
3-1
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Information and Data Acquisition
Initial Phase I
Toxicity Characterization
Data Base on POTW Operation
and Performance
Background-Historical Information
Discharge Permits
Process Control Data
Biological Treatment Inhibition
Chlorination Problems
Treatment Bypasses
Process Sidestream Discharges
Sludge Toxicity
Toxicity or Toxics Pass-Through
No
Yes
1
r
Bench Scale
Conventional
Treatability
Tests
1
1
r
Pilot Scale
Conventional
Treatability
Tests
i
r
Toxicity
Identification
Evaluation
(Figure 4-1)
Toxicity/Toxics
Pass Through
Toxicity Control
Selection
Figure 3-1. Plant performance evaluation.
removal during aerobic biological treatment can occur
by biodegradation, adsorption onto the biological floe,
and by volatilization of volatile constituents. Key
factors affecting toxics removal are the tendency for
toxics to biodegrade, volatilize, or sorb onto solids
and the degree to which toxics will inhibit the
biological process.
Aerobic biological treatment systems that are typically
used in POTWs are activated sludge, trickling filter
and rotating biological contactor (RB3) processes. To
simplify the discussion of aerobic biological treatment
systems, the following subsections will focus on the
performance evaluation of the activated sludge
process, which is the process most widely used in
POTWs.
The parameters that are used to evaluate the
operational capability of an activated sludge system
include organic loading, oxygen requirement and
mean cell retention time (MCRT). Operating values
for these parameters can be compared to design
specifications or recommended criteria to determine
3-2
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how well the activated sludge process is being
operated.
Organic Loading -
Organic loading on an activated sludge system affects
the organic removal. efficiency, oxygen requirement
and sludge production of the process. The most
common measure Of organic loading in suspended
growth processes is the food-to-microorganism
(F/M) ratio, which is the organic load removed per
unit of mixed liquor volatile suspended solids
(MLVSS) in the aeration basin per unit time. High F/M
ratios (i.e., high organic loading) will result in low
organic removal efficiency, low oxygen requirement
and high sludge production. Low F/M ratios (i.e., low
organic loading) will cause high organic removal
efficiencies and low sludge production, but high
oxygen requirements. For optimal biological
treatment, the F/M ratio in an activated sludge system
is typically maintained in the range of 0.2 to 0.4 Ib
BODs/lb MLVSS-day for conventional activated
sludge, 0.05 to 0.15 Ib BOD5/lb MLVSS-day for
extended aeration, and 0.2 to 0.6 Ib BODs/lb
MLVSS-day for contact stabilization (Metcalf and
Eddy, 1979).
An activated sludge process operating at an F/M ratio
that is substantially lower than the design F/M ratio
may indicate biological treatment performance
problems. For example, the Patapsco Wastewater
Treatment Plant in Baltimore, Maryland was operated
at an F/M ratio of 0.40 Ib BODs/lb MLVSS-day
instead of the design F/M ratio of 0.55 Ib BODs/lb
MLVSS-day, because the POTW could not achieve
consistent wastewater treatment at the higher organic
loading. The decreased treatment capacity at the
POTW was thought to be due to the toxic effect that
industrial wastewaters had on the activated sludge
biomass (Slattery, 1987).
Oxygen Requirement ~
Microorganisms in the activated sludge system
require oxygen to metabolize the organic material in
the wastewater. Oxygen deficient conditions can
result in lower treatment capacity, and hence a
greater potential for toxics pass-through. To ensure
an adequate supply of oxygen, the dissolved oxygen
(DO) level should be maintained above 2 mg/l.
Typical air requirements are 1,500 cu ft/lb BODs load
for conventional activated sludge and contact
stabilization, and 2,000 cu ft/lb BODs load for
extended aeration (USEPA, 1984).
The transfer of oxygen from the gas phase to the
liquid phase is a function of the aeration equipment
and the basin mixing conditions. EPA's Composite
Correction Program Manual (1984) describes a
procedure for estimating oxygen transfer capacity in
aerators based on equipment specifications. Another
estimate of oxygen transfer capacity involves
comparing the measured oxygen uptake rate (OUR)
of the biomass to the calculated theoretical oxygen
demand (USEPA, 1984) for the aeration system. If
the OUR results indicate an oxygen demand that is
greater than the calculated oxygen demand, the
oxygen supply may be inadequate. The opposite case
(i.e., higher theoretical oxygen demand than actual
oxygen demand) is preferred; however, a substantial
difference may indicate inhibition of biomass activity.
OUR measurements were used to document the
start-up performance of the activated sludge
treatment process at the Patapsco Wastewater
Treatment Plant. During the start-up of the biological
process, the OUR in the biomass averaged 20
mg/l/hr/g MLSS, and the POTW frequently exceeded
its conventional pollutant permit limits (Botts et al.,
1987). As the biological system became acclimated to
the wastewater, the effluent quality improved and the
biomass OUR increased to an average of 50 mq/l/hr/q
MLSS.
Mean Cell Residence Time -
In the course of biological treatment, the activated
sludge microorganisms convert some of the organic
matter in the wastewater to new cell mass. To
achieve optimal treatment, the biomass concentration
in the aeration tank is held at a constant level by
routinely wasting the excess sludge. Sludge mass
control can be practiced by maintaining a consistent
average age of activated sludge (i.e., mean cell
residence time) in the system. Mean cell residence
time (MCRT) is calculated by dividing the total sludge
mass in the system by the amount of sludge that is
wasted each day.
Typical MCRTs for aeration processes are: 6 to 12
days for conventional activated sludge, 10 to 30 days
for contact stabilization and 20 to 40 days for
extended aeration (USEPA, 1984). During the
Patapsco TRE, the MCRT of the pure oxygen
activated sludge process increased from an average
13.8 days to 16.9 days over a 9 month period (Botts
et.al., 1987). This increase in MCRT appeared to
cause a corresponding decrease in OUR in the
biomass from 46.7 mg O2/hr/g MLSS to 25.2 mg
O2/hr/g MLSS over the same period. The increase in
MCRT appeared to be limiting biomass activity,
however, effluent quality as measured by toxicity and
conventional pollutant removal was not affected.
Secondary Clarification
In order for the activated sludge process to operate
efficiently, the secondary clarifier must effectively
separate solids from the liquid phase and concentrate
the solids for subsequent return to the aeration basin.
Solids-liquid separation is influenced to a large
degree by the aeration basin operating conditions
such as DO levels, F/M ratio and MCRT. Secondary
3-3
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clarifier factors also have an important effect on solids
clarification.
Sludge settling characteristics are affected by how
the aeration basin is operated. Low DO levels in the
aeration basin promote the growth of filamentous
bacteria which can hinder solids settling, whereas
high DO levels lead to the growth of fast settling
zoogleal-type bacteria. At very high organic loadings
(high F/M) the activated sludge can be dispersed and
will not settle well. An example of this condition was
observed at the East Side Sewage Treatment Plant in
Oswego, New York, which experienced sludge
bulking due to high influent organic loadings (USEPA,
1984). Sludge settleability was improved by
increasing the MCRT and the sludge return rate.
The performance of secondary, clarifiers in solids-
liquid separation is dependent on a variety of factors
including clarifier configuration, SOR, clarifier depth at
the wiers, the type of sludge removal mechanism,
and the return sludge flow rate. The Composite
Correction Program Manual (1984) describes a
system for scoring secondary clarifier performance
based on these factors.
Process Sidestreams and Wastewater Bypasses
Some wastewater and sludge treatment processes
can produce sidestream wastes that may have a
deleterious effect on the wastewater treatment
system or might contribute to the effluent toxicity. In
addition raw or partially treated wastewater that
bypasses part or all of the wastewater treatment
system can add substantial toxicity to POTW
discharge^).
Examples of POTW sidestreams include sludge
processing wastewaters from thickening, digestion,
and dewatering of sludges, cooling water blowdown,
and backwash from tertiary filters. Of these
wastewaters, anaerobic digestion and sludge
dewatering sidestreams can contain high
concentrations of organic material (BODs) and
nutrients (nitrogen and phosphorus) which can
represent a significant loading to the aeration basin. In
addition, these and other sidestreams may contain
toxic material such as metals from sludge dewatering
treatment that may pass through the POTW.
In some municipalities, stormwaters and sewage are
still collected in the same sewer system. When a
large storm event occurs, the combined sewer
wastewater is often diverted away from all or part of
the POTW to prevent hydraulic over loading, and the
bypass is discharged directly to the receiving water.
Combined sewer overflows (CSOs) can cause short-
term exceedances in discharge permit limits for both
toxic and conventional pollutants.
The PPE should include a listing of all process
sidestreams and wastewater bypasses in the POTW,
and a review of the data on each of these waste-
streams. Additional analytical and. toxicity data may be
needed to characterize the possible toxic constituents
and toxicity of the wastestreams. This information can
be used to determine if process sidestreams are a
significant source of pollutants or toxicity, and
whether or not current treatment practices are
sufficient to remove the toxicity. Information on the
frequency and volume of CSOs, relative to the
receiving wasteflow, can indicate if CSOs are a
problem.
Disinfection
Disinfection is generally achieved by treating the
secondary effluent with chlorine and allowing a
sufficient contact period prior to discharge. The
chlorine dosage is usually based on the required level
of residual chlorine to be maintained in the final
effluent which is specified in the NPDES permit.
The chlorine disinfection process should be carefully
evaluated because residual chlorine and other by-
products of chlorination (i.e., mono- and dichloro-
amines) are toxic to aquatic life (Brungs, 1973). The
PPE focuses on the minimum amount of chlorine that
must be applied to achieve the desired residual
chlorine concentration. Observations should be made
to determine how close the actual residual chlorine
level is to the required minimum level. For example,
an average residual chlorine level of 3.0 mg/l for a
POTW with a minimum permit level of 1.0 mg/l
chlorine would indicate excessive chlorination.
If dechlorination is practiced following chlorination,
information on the type and amount of oxidant-
reducing material used should be obtained; Some
dechlorinating agents such as sulfur dioxide may be
toxic to aquatic life at high concentrations.
Optional TIE Phase I Tests
Optional TIE Phase I analyses (Mount and
Anderson-Carnahan, 1988a) can be conducted in
parallel with the above operations and performance
review to obtain information on the types of
compounds causing the effluent toxicity. An overview
of the Phase I procedure is described in Section 4 of
this document.
The TIE Phase I testing in the PPE focuses on
characterizing toxicants that may be present in the
effluent because of inadequate treatment
performance or routine operating practices. Although
the Phase I results provide only an initial indication of
the effluent toxicants, when taken together with the
PPE data and a knowledge of the POTW treatment
operations, possible in-plant toxicants can be
suggested based on the "weight of evidence". .Using
this information, treatability tests can be devised to
3-4
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evaluate procedures for removing the suspected
toxicants from the effluent.
The TIE Phase I testing includes several
characterization steps that can be used to indicate
the presence of "in-plant toxicants" such as
suspended solids, ammonia and chlorine. One step
involves filtration to remove effluent particles, which
include residual suspended solids resulting from
biological treatment. By testing the toxicity of
unfiltered and filtered samples, it is possible to
determine whether or not the effluent toxicity is
associated with these particles. Another Phase I step
involves pH adjustment of the effluent sample to shift
the equilibrium concentration of ammonia between its
toxic form (NHs) and its essentially nontoxic form
(NH4 + ). As pH increases, the percentage of total
ammonia (NH3 -+ NH4 + ) present as NHs increases.
If adjusting the effluent sample pH to 8 increases the
toxicity or if lowering the effluent sample pH to 6
decreases the toxicity, the identity of the effluent
toxicant would be consistent with ammonia. Caution
should be used in drawing preliminary conclusions
about these data, because the toxicant could actually
be something that behaves in the same manner as
ammonia. A third Phase I step is designed to indicate
whether or not wastewater oxidants such as total
residual chlorine (i.e., free chlorine and mono- and
dichloroamines) are causing the toxicity. Thiosulfate,
a reducing agent, is added to aliquots of the effluent
sample to eliminate total residual chlorine (TRC).
Toxicity tests prior to and following thiosulfate
treatment are used to indicate if TRC is present in
toxic amounts in the effluent.
It is important to .note that each of the TIE Phase I
characterization steps described above addresses a
broad class of toxicants rather than specific effluent
constituents such as ammonia and TRC (Mount and
Anderson-Carnahan, 1988a). For example, the
oxidants that are • neutralized in the thiosulfate
treatment step include bromine, iodine and
manganous ions in addition to TRC. Thus, to
substantiate the initial indication that specific toxicants
are causing effluent toxicity, the Phase I results
should be compared with information from the POTW
operations and performance review. Using the
previous example, the assumption that TRC is
causing oxidant toxicity would be corroborated if
operations data show that the POTW maintains toxic
concentrations of chlorine in the final effluent.
Conventional Wastewater Treatability
Testing
The operations and performance review information
may identify areas in the POTW where improvements
in conventional pollutant treatment may reduce
toxicity pass-through. This information and the
optional TIE Phase I data may also indicate in-plant
sources of toxicants such as process sidestream by-
passes or over chlorination that are causing effluent
toxicity. IJsing these data, a wastewater treatability
program can be devised and implemented to assess
in-plant options for improving conventional treatment
and eliminating in-plant sources of toxicity.
Treatability studies are recommended prior to
comprehensive TIE testing (Section 4) only in
situations where improvements in treatment
operations and performance are needed to attain
acceptable conventional pollutant treatment. These
studies should focus on conventional pollutant
treatment deficiencies which are suspected of
contributing to effluent toxicity. The scope of the
treatability studies program should be based on clear
evidence of a consistent treatment deficiency causing
toxicity over time. If sufficient information is not
available to develop a straightforward treatability
program, additional data must be gathered in the
subsequent stages of the TRE before in-plant
toxicity control (Section 7) can be evaluated.
Treatability studies can range from a simple
evaluation such as testing TRC removal by
dechlorination to an extensive effort involving long-
term bench- and pilot-scale work. Prior to
beginning these studies, the POTW operations and
performance data and the optional TIE Phase I results
should be carefully reviewed and an appropriate
treatability test program should be developed using
best professional judgement. It may be necessary to
more completely assess the nature and variability of
the effluent toxicity (Section 4) prior to implementing
an extensive treatability effort.
A treatability program can be devised to evaluate
modifications in existing treatment processes. The
evaluation of additional treatment units should be
attempted only after further effluent characterization
studies (i.e., TIE) have been performed. PPE
treatability testing may involve physical/chemical
treatment approaches such as coagulation and
precipitation, solids sedimentation, granular media
filtration, and powdered activated carbon adsorption,
or biological treatment approaches such as activated
sludge or sludge digestion. Because toxicity control is
the ultimate goal of the TRE, toxicity tests should be
performed in addition to the conventional pollutant
analyses normally conducted in treatability studies,
Toxicity tests are used to assess the capability of the
treatment modifications for toxicity reduction.
The following subsections briefly describe some of
the treatability tests that can be used to determine if
improvements in conventional pollutant treatment will
reduce effluent toxicity. As shown in Figure 3-1; if
this testing is successful in identifying improvements
in conventional pollutant treatment that will achieve
acceptable levels of effluent toxicity, the TRE
proceeds to the selection and implementation' of
3-5
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those options (Sections 8 and 9). If, however, the
treatability data indicate that improved in-plant
treatment will not reduce effluent toxicity to
acceptable levels, further effluent toxicity
characterization is required using the TIE procedures
(Section 4).
Coagulation and Precipitation
Coagulation is the addition of a chemical such as
polymer or ferric chloride to wastewater that causes
the formation of flocculant suspensions or insoluble
precipitates. Coagulation can be applied in POTWs to
improve suspended solids settling or remove
phosphorus, heavy metals, and paniculate toxicity.
The optimum conditions for coagulation can be
determined by conducting a series of jar tests. These
tests are used to establish the optimum type and
dose of coagulant, the proper mixing conditions, and
the flocculant settling rates (Adams et al., 1981).
Sedimentation
Sedimentation is the process employed to remove
suspended solids or flocculant suspensions from the
wastewater. In general sedimentation in POTWs is
characterized by flocculant settling for wastewater
(i.e., primary clarification) and zone settling for mixed
liquors (i.e., secondary clarification) and sewage
sludges (i.e., sludge thickening).
Flocculant settling rates can be converted to a
clarifier SOR by measuring the flocculant percent
removal with time in a settling column test (Adams
et.al., 1981). Using the optimum range of flocculant
conditions determined in jar tests, a series of settling
column tests can be performed to compare particle
settling profiles for various coagulant doses and
mixing conditions.
Zone settling can also be evaluated in settling column
tests. The settling velocity of mixed liquor or sludge is
determined by measuring the subsidence of the
liquid-solids interface over time (Adams et.al., 1981).
The test is repeated using the anticipated range of
suspended solids loading to the clarifier. Test results
are used to calculate a solids flux curve that can be
used for clarifier design.
Activated Sludge
Activated sludge is an aerobic treatment process that
converts organic matter to settleable microorganisms.
Continuous flow and batch biological reactor tests are
used to assess pollutant or toxicity treatability, and
predict the process kinetics of an activated sludge
system. A series of bioreactors are generally operated
under a range of F/M values to determine optimum
operating conditions (Adams et al., 1981).
Bioreactor performance is evaluated by measuring
pollutant removals, OUR, MLVSS and the zone
settling velocity (ZSV) of the sludge. These
measurements are used to determine the
biodegradation kinetics of the wastewater and the
preferred sludge settling conditions.
Granular Media Filtration
Some POTWs utilize filtration processes following
secondary clarification to enhance suspended solids
removal. Filtration performance is influenced by the
physical/chemical properties of the granular media
and the wastewater.
The main parameters to be varied in filtration testing
include hydraulic loading rate, type and configuration
of the media, and, if necessary, type and dose of
chemical coagulant (Adams et al., 1981). Results of
filtration testing are used to correlate suspended
solids removal with flow rate, headless through the
filter with time, and differential headloss with solids
accumulation on the filter media.
Activated Carbon Adsorption
Activated carbon may be applied in powdered form to
the activated sludge process. The capability of carbon
adsorption for treatment of organic wastewater
constituents or toxicity is determined by conducting
batch isotherm tests and continuous-flow tests
(Adams et al., 1981).
The effectiveness of carbon in removing BODs,
selected organic contaminants (e.g., phenols) or
toxicity is predicted by adding known amounts of
powdered activated carbon to a series of batch
wastewater samples and measuring removal of the
organic constituents or toxicity. The equilibrium
relationship between a wastewater and carbon can
usually be described either by a Langmier or
Freundlich isotherm. A plot of equilibrium
concentration versus carbon capacity is used to
select the required carbon concentration for
powdered activated carbon (PAC)-activated sludge
processes.
Continuous-flow tests are required to confirm the
batch isotherm results. PAC tests involve adding PAC
to bench- or pilot-scale biological reactors and
monitoring the removal of the organic wastewater
constituents or toxicity.
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Section 4
Toxicity Identification Evaluation
Introduction
Once the presence of toxicity has been established,
the primary components of toxicity can be
characterized and possibly identified through the use
of toxicity identification evaluation procedures. These
procedures relate the wastewater components',
physical/chemical characteristics to their toxicological
characteristics in a attempt to identify the
compound(s) causing effluent toxicity.
The TIE procedures as described by Mount and
Anderson-Carnahan (1988a, 1988b) and Mount
(1988) consist of three phases: Phase I involves
characterization of the toxic wastewater components;
Phase II is designed to specifically identify the
toxicants of concern; and Phase III is conducted to
confirm the suspected toxicants. Figure 4-1 presents
the= logical progression of these three phases within
the framework of a municipal TRE.
The TIE procedures are applied to POTW effluent
wastewater samples. A sufficient number of effluent
samples should be collected to characterize the
magnitude and variability of the effluent toxicants over
time. To ensure that the samples are representative
of the effluent wastewater, a large number of sam-
ples may need to be collected. Sampling re-
quirements for TIE testing are described in Section
13. In addition to POTW effluent TIE testing, the
Phase I protocol may be applied to batch treated
sewer wastewaters, as described in Section 6, to
characterize the components of the POTW influent
toxicity.
Toxicity Tests
Toxicity identification evaluations rely on the use of
aquatic toxicity tests to detect the compounds
causing wastewater toxicity. Acute toxicity tests are
generally used to indicate the presence of toxicants
as the effluent is manipulated in TIE testing.
Presently, the TIE procedures do not address chronic
toxicity directly; however, TIE testing can be
performed on effluents violating chronic toxicity limits,
provided that the effluent causes significant lethality
(e.g., >20% mortality in 100% effluent) in an acute
exposure period (i.e., 48 to 96 hr.). In this case the
compound(s) causing acute toxicity are assumed to
be the same compound(s) causing chronic toxicity.
This hypothesis is tested in the Phase III tests
(Mount, 1988). ' ' .
The sensitivities of the test organisms used in toxicity
tests can vary from species to species, therefore it is
recommended that multiple species testing be
performed in the initial stages of the TIE to select an
appropriately sensitive species for the TIE program.
Another criterion in test species selection is that the
species be cost-effective to use, because of the
large number of samples that may need to be tested.
Test species commonly used for TIE toxicity tests are
Ceriodaphnia or Daphnia magna; however, other
species such as fathead minnows (Pimephates
prometas) can also be used.
Saltwater species are not recommended, because the
tolerances of marine organisms to the TIE effluent
manipulations have not been measured (Mount and
Anderson-Carnahan, 1988a). In situations where the
POTW effluent is discharged to saline receiving
waters, a freshwater species that is responsive to the
same toxicants as the marine species should be
chosen. Phase III involves minimal effluent
manipulation and a marine species should be used to
confirm the Phase I and II freshwater species results.
Toxicity test procedures for TIEs are described in the
Phase I manual (Mount and Anderson-Carnahan,
1988a). The test organisms are placed into six test
vessels: one containing the highest test sample
concentration; four containing the appropriate range
of sample dilutions; and one containing only dilution
water which serves as the control. Following an
appropriate exposure period, the test organism
mortality is determined and an LCso value ,(i-e.
percent sample concentration causing 50% mortality)
is calculated. These tests are usually performed with
minimal quality assurance (e.g. duplicates may not be
required) in. an effort to collect as much data on the
sample toxicity, as quickly and inexpensively as
possible.
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Evidence of Toxicity Pass-Through or
Treatment Inhibition
Phase I Toxicity Characterization
Initial Toxicity
Baseline Toxicity
pH Adjustment
Aeration
Filtration
Cia Solid Phase
Extraction/El ution
Oxidant Reduction
EDTA Chelation
Graduated pH
Information and
Data Acquisition
Pretreatment Program
Data
Additional
Information
Required
Phase II Toxicant Identification
Specific Chemical Analytical Method
Phase III Toxicant Confirmation Procedures
Additional
Information
Required
Toxicity Control
Selection
Toxicity Source
Evaluation Tier I
(Figure 5-1)
,
r
POTWIn-Plant Control
Evaluation
(Figure 7-1 )
Figure 4-1. Toxicity identification evaluation.
When Phase III is reached, definitive toxicity tests
using standard EPA procedures (Horning and Weber,
1985, Peltier and Weber, 1985, Weber et al., 1988)
are recommended to confirm the suspected toxicants.
These tests should utilize the same test species that
is required for NPDES biomonitoring.
Toxicity Characterization and Toxicant
Identification Procedures
The effluents of some municipal treatment facilities
can be extremely complex, particularly facilities which
receive a significant amount of industrial wastewater.
4-2
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These effluents have posed a problem in attempting
to determine the compound(s) causing toxicity.
Furthermore, effluents from POTWs with little or no
industrial inputs have proven to be difficult to
characterize. Nonetheless, the TIE procedures are
useful in the identification of the toxic compound(s) in
POTW effluents. These procedures allow the toxicity
to be traced to a particular class of compounds and
sometimes to a particular compound(s).
Phase I - Toxicity Characterization
The first step in the TIE is to characterize the effluent
toxicity using the Phase I approach (Mount and
Anderson-Carnahan, 1988a). This procedure
involves the use of several bench-top treatment
steps to determine the types of toxic components in
the effluent. Initially, the whole wastewater sample is
evaluated for "baseline" toxicity. If it is toxic, aliquots
of the sample are treated to remove certain types of
compounds and the resulting acute toxicity of these
treated aliquots is measured.
The Phase I characterization steps consist of toxicity
degradation, aeration, filtration, Cia solid phase
extraction (all of these procedures with and without
pH adjustment), pH adjustment, oxidant-reduction,
EDTA chelation, and graduated pH treatments. The
toxicity tests on aerated wastewater samples are
used to indicate if toxicity is associated with volatile or
oxidizable compounds. The filtration step is designed
to determine whether toxicity is in the suspended
particulate phase or in the soluble fraction. Aeration,
in conjunction with pH adjustment is used to evaluate
toxicants with volatility, such as ammonia or hydrogen
sulfide. The toxicity associated with the presence of
oxidants is evaluated through sodium thiosulfate
addition. Cationic metal toxicity is evaluated through
graduated EDTA addition. An aliquot of the effluent
sample is also passed through a C-\Q solid phase
extraction (SPE) column that selectively removes
non-polar organic compounds. If the effluent toxicity
is removed or reduced by this treatment, the column
is then eluted with.methanol and the eluant is tested
for toxicity. If these Phase I tests are inadequate to
characterize the toxicants, other techniques can be
used such as ion exchange resins for anions and
cations; activated carbon for various inorganic and
organic compounds; zeolite resins for ammonia; and
molecular sieves such as Sephadex resins which
separate compounds by molecular weight.
Pretreatment program data (Table 2-2) may provide
useful information to assist in the Phase I
characterization. By reviewing available information on
the pretreatment program, compounds that are known
to be toxic or problematic in the POTW can be
compared to the Phase I results to assist in indicating
the effluent toxicants. This data comparison should
not, however, replace the Phase II and III analyses.
After successful completion of Phase I, it may not be
necessary to proceed to Phases II and III. If the
effluent toxicity can be isolated to a class of
compounds (i.e., non-polar organics, suspended
particulates, volatile organics), treatability studies can
be designed to evaluate removal of the compounds
causing toxicity. These studies may involved bench-
scale or pilot-scale testing procedures described in
Section 7.
Phase II - Causative Toxicant Identification
The Phase II procedure manual (Mount and
Anderson-Carnahan, 1988b) describes specific test
methods that can be used to further identify specific
causative agents such as non-polar organic
compounds, ammonia, cationic metals, or chlorine.
These methods are not intended as final proof that
the compounds are causing toxicity. Phase III tests
are required to confirm that the toxicants are the
compounds consistently causing toxicity. Depending
on the characteristics of the causative chemicals,
Phase II methods may entail the use of reverse phase
HPLC columns to further separate non-polar organic
toxicants into more narrow fractions. This separation
technique allows the identification of specific toxicants
using gas chromatography/mass spectrometry
(GC/MS) procedures.
Additional methods for identification of toxic effluent
components include: the equitoxic solution test which
evaluates the effect of pH adjustment and dilution on
ammonia toxicity; the zeolite resin test which also can
be used to identify ammonia toxicity; and atomic
absorption or Inductively Coupled Plasma
Spectrometry (ICP) to determine which cationic
metals are the toxicants. Toxicant identification
procedures for other groups of causative toxicants will
be published by EPA as they become available.
Phase HI - Causative Toxicant Confirmation
The next step in the TIE is Phase III which is the
toxicant confirmation procedure (Mount, 1988). The
toxicants identified in Phase II are confirmed by a
series of test steps including observation of test
organisms symptoms; additional species toxicity
testing; and correlation of toxicity and toxicant
concentration from multiple samples.
4-3
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Section 5
Toxicity Source Evaluation - Tier I
Introduction
A toxicity source evaluation is conducted to locate the
sources of influent toxicity or toxics that are
contributing to the POTW effluent toxicity. This
evaluation is performed in two tiers. Tier I, which is
discussed in this section, involves sampling
wastewater of indirect dischargers or sewer lines and
analyzing the wastewaters for toxics and/or toxicity.
Tier II, which is described in Section 6, is performed
to confirm the suspected sources of toxicity identified
in Tier I testing.
The flow diagram for the Tier I source evaluation is
presented in Figure 5-1. Selection of sampling
locations is based on evidence that a source
contributes toxicants causing POTW effluent toxicity
or discharges substantial levels of potentially toxic
pollutants. Sampling of wastewaters from indirect
dischargers is recommended where existing
pretreatment program data or TIE results are
adequate to indicate that the dischargers may
contribute toxic pollutants that cause POTW effluent
toxicity. Sewer line sampling can be used to locate
toxic sources by process of elimination, if
pretreatment program information and TIE data are
lacking, or sampling of indirect dischargers is not
feasible (e.g., large number of IDs).
The choice of chemical-specific analyses or toxicity
tests for source tracking will depend on the quality of
the TIE data on the POTW effluent. Chemical-
specific investigation is recommended in cases where
the effluent toxicants have been identified and
presumably can be traced to the responsible sewer
dischargers. In situations where TIE data indicate that
specific industrial chemicals such as copper or phenol
are the effluent toxicants, the TRE should proceed to
the evaluation of local pretreatment limits as
described in Section 8.
Toxicity tracking is required in situations where TIE
data on specific toxicants are not definitive. Prior to
toxicity analysis, sewer samples are afforded the
same:level of biological treatment as provided by the
POTW for its influent wastewaters. If toxicity tracking
is successful in locating sources that are contributing
toxicity, the TRE proceeds to the Tier II source
evaluation to confirm the toxic indirect dischargers. At
this point, the POTW may require the Ills to conduct
a TRE to reduce ID wastewater toxicity. It may also
be possible in a few instances to correlate the
pretreatment program data gathered at the beginning
of the TRE (Section 2) with the effluent toxicity
results to identify the influent sources of toxicity.
Sampling Location
Sampling locations for Tier I testing are established
by reviewing the pretreatment program data (Table
2-2) and the TIE results, and selecting the sources
that contribute relatively high loadings of potentially
toxic pollutants or toxicants identified in TIE tests.
Where possible, the selection of sampling locations
should be based on TIE results, because the
toxicants causing the effluent toxicity are the
pollutants that must be controlled. Sampling may be
conducted at the point where the IU discharges its
wastewater to the sewer or in the sewer lines of the
sewer collection system, if no IU appears to be the
source of the toxicants. A plan for sewer line
sampling can be devised to track toxic sources
through a process of elimination of segments of the
collection system (USEPA, 1983a).
The choice of IU discharge sampling or sewer line
sampling will depend on the number of lUs
contributing to the POTW, the quality of the
pretreatment program data, and the TIE results. IU
discharge sampling is recommended where the:
« Number of lUs is small enough so that sufficient
test data can be collected with the allocated
resources;
« Pretreatment program data are sufficient to
characterize each of the lUs; and
• TIE data indicate POTW effluent toxicants that
can be attributed to selected lUs.
In the Patapsco TRE indirect dischargers were
selected for sampling based on evidence that the lUs
contributed substantial loadings of toxicity (as
5-1
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Results of
Toxicity Identification
Evaluation
(Figure 4-1)
r
Sample Collection
Sewers/Point Discharges
Chemical-Specific
Investigation of
Selected Point Discharges or
Collection System
Refractory Toxicity
Assessment of Selected
Point Discharges or
Collection System
Information and
Data Acquisition
Pretreatment Program
Review (PPR)
Tier II: Toxicitv Source
Evaluation (Figure 6-1)
POTW In-PIant Control
Evaluation (Figure 7-1)
Yes
No
Additional
Information
Required
Toxicity Control
Selection
Figure 5-1. Tier I: toxicity source evaluation.
measured by MicrotoxTM) and toxicants (non-polar
organic material) identified by TIE tests of POTW
effluent (Botts etal., 1987). A description of the
Patapsco study is given in Appendix A.
Sewer line sampling is recommended where:
• A sewer line sampling plan can be developed
that will allow a more efficient method of toxicity
tracking than sampling ID discharges;
• Pretreatment program data are limited or
unavailable; and
• Sources of toxicants identified during the TIE are
not obvious.
The Town of Billerica, Massachusetts, utilized a
sewer line sampling approach to identify areas within
the sewer collection system that contribute toxicity to
Ihe Town's wastewater treatment plant (Durkin et.al.,
1987). A description of the Billerica study is provided
in Appendix A.
Whether sampling of IU discharges or sewer lines is
conducted, 24-hour flow proportional samples are
recommended to characterize daily variations in toxics
or toxicity while accounting for variations in flow. Flow
data must be gathered in order to determine the
relative contributions of toxicants or toxicity from the
IDs. Other considerations for Tier I sampling are
described in Section 13. QA/QC sampling
requirements are discussed in Section 10.
Chemical-Specific Investigation
A chemical-specific approach can be used to trace
the influent sources of toxics, if definitive TIE data on
the specific toxicants causing POTW effluent toxicity
are available. This approach is not recommended in
cases where the TIE data only indicate a broad class
of compounds (e.g., polar organic compounds),
because the toxicants may be contributed by a large
5-2
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number and variety of sources which will be difficult
to pinpoint by chemical tracking.
The chemical-specific approach involves testing IU
discharges or sewer line samples for specific
toxicants using chemical analysis techniques. In some
cases existing pretreatment program data may be
adequate to determine the Ills that are contributing
the toxicants. It is likely, however, that further
sampling and analysis will be necessary, because
many toxicants other than those typically monitored
(i.e., priority pollutants) are present in ID discharges.
Existing pretreatment program data can be used to
reduce the amount of sampling and analysis by
indicating which sources contribute toxics that are
similar to the effluent toxicants.
Chemical analysis methods for priority pollutants are
described in several EPA documents (USEPA 1979a,
1979b, 1980, 1985b) and Standard Methods for the
Examination of Water and Wastewater (APHA, 1985).
Analytical techniques for non-priority pollutants can
be found in American Society for Testing and
Materials (ASTM) manuals and analytical chemistry
journals such as the Analytical Chemistry Journal.
The selected analytical method should be verified in
the laboratory prior to sampling and analysis. Prior to
analysis, a literature search should be made to
determine if the toxicant could be a biodegradation
product resulting from POTW treatment. Where clear
evidence is available to show that the toxicant is a
treatment by-product, the sewer sample should be
analyzed for the precursor form(s) of the toxicant as
well as the toxicant.
In cases where Tier I chemical tracking is successful
in locating the IDs that are responsible for the POTW
effluent toxicants, the TRE process can move to the
selection and development of local pretreatment
regulations (Section 6). If the responsible ILJs can not
be located, the TIE results should be reviewed to
confirm previous conclusions. The chemical analysis
results should also be carefully reviewed to determine
if errors or wastewater matrix effects may have
caused inaccurate results. In cases where the
chemical-specific approach is ultimately not
successful, the Tier I testing should be repeated
using toxicity tests in lieu of chemical analysis as
described later in this section.
Pretreatment Program Review
It may be possible in a few cases to identify the toxic
influent sources by comparing pretreatment program
information on suspected influent toxics to chemical-
specific data on POTW effluent toxics. This
pretreatment program review (PPR) approach is
recommended only in situations where the POTW has
only a few IDs which have relatively non-complex
discharges.
The PPR approach was applied at the Mt. Airey
POTW in North Carolina (Diehl and Moore, 1987)
which receives industrial wastewater from only a few
sources, predominately textile industries. In the Mt.
Airey TRE, detailed information on the manufacturing
processes and wastewater discharges of the
industries was gathered (see Table 2-2), including
data on the toxicity and biodegradability of raw and
manufactured chemicals as provided in material
safety data sheets (MSDS). This information was
used to identify industrial chemicals with relatively
high potential toxicity that may be present in the
POTW effluent. Subsequent chemical analysis of the
POTW effluent was performed using methods
specifically designed to measure for the suspected
industrial toxics. The chemical analysis results were
compared with water quality criteria and toxicity
values for individual compounds. Using this approach,
alkyl phenol ethoxylate surfactants, phthalate esters
and chlorinated solvents, largely attributed to textile
industries, were identified as the primary toxics
causing the POTW effluent toxicity.
A description of PPR methods is provided in
Appendix A. The methods described involve a direct
comparison of IU chemical data to POTW effluent
toxicity. It is important to emphasize that drawing
preliminary conclusions based on PPR results can be
misleading, because IU monitoring information could
be incomplete, chemical analysis techniques may not
be sensitive to low levels of effluent toxics, and the
estimated toxicity of individual compounds may not
reflect the whole effluent toxicity. Due to these
factors, comparisons of suspected toxicants to
effluent toxicity may yield false correlations.
Whenever possible, results of TIE testing should be
used in lieu of PPR results, because the TIE. test
directly measures the relative toxicity of the effluent
constituents.
Refractory Toxicity Assessment
Influent toxicity tracking is necessary when TIE
testing is only able to identify a broad class of
toxicants, rather than specific compounds, that are
causing the POTW effluent toxicity. Toxicity tracking
may also be required in situations where there are a
large number of effluent toxicants and the occurrence
of these toxicants in the POTW effluent is highly
variable. In this case toxicity testing may be more
cost-effective than chemical analysis.
The toxicity of influent wastewaters is not necessarily
the same toxicity that is observed in the POTW
effluent, because the POTW is capable of removing
or degrading toxic wastewater constituents. The level
5-3
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of toxicity in a sewer discharge which could
potentially pass through the POTW must be estimated
by treating sewer samples in a simulation of the
POTW process prior to toxicity analysis. Based on the
experience to date, a simulation of activated sludge
treatment has been developed for predicting the
potential for a sewer discharge to contribute to the
POTW effluent toxicity. This treatment step accounts
for the toxicity removal provided by the POTW. A
toxicity tracking approach can be applied to ID
discharges and sewer line wastewaters to locate the
sources contributing either acute or chronic toxicity
that is refractory to POTW treatment.
The refractory toxicity assessment (RTA) approach
involves treating sewer samples in aerobic batch
bioreactors and testing the resulting effluents for
toxicity. Batch bioreactors have been used by several
researchers to screen wastewaters for activated
sludge inhibition (Grady, 1985, Adams et al., 1981,
Philbrook and Grady, 1987, and Kang et al., 1983)
and non-biodegradable aquatic toxicity (Dague and
Hagelstein, 1984, Lankford et al., 1987, and Sullivan
et al., 1987). Dague and Hagelstein (1984) and
Lankford et al. (1987) have found that toxicity
measurements coupled with bioreactor tests can be a
pragmatic way to evaluate refractory wastewater
toxicity.
The RTA protocol was developed in the Patapsco
TRE (Botts et ai., 1987) to evaluate the potential for
indirect dischargers to contribute toxicity that was
refractory to treatment provided by the POTW. This
protocol involves treating sewer samples in a bench-
scale batch reactor that is designed to simulate, as
close as possible, the operating characteristics of the
POTW's activated sludge process (e.g., MLSS
concentration, DO level and F/M). Acute and/or
chronic toxicity measurements of the batch effluent
indicate the amount of refractory toxicity in the sewer
sample. In the protocol, coarse filtration of the decant
from the batch reactor is used to produce the batch
effluent. Decant-filtration more closely simulates
sedimentation in the full scale plant because batch
settling alone is not as efficient as the POTW settling
process.
A general description of the RTA procedure is
presented as follows. A step by step protocol for
applying the RTA test to sewer wastewaters is
provided in Table 5-1. It is important to note that the
RTA procedure was developed based upon the
experience to date and additional research is in
progress to further refine the protocol. Public works
managers should recognize that variations of the RTA
protocol can be used to address site-specific
circumstances. Best professional judgment will be
important in applying the procedures and in
interpreting the results.
Biomass Toxicity Measurement
During the Patapsco TRE, filtrate from coarse
filtration of the POTW return activated sludge (RAS)
was found to be acutely toxic to Ceriodaphnia (Botts
et al., 1987). The high level of toxicity from residual
biomass in the filtrate masked the measurement of
batch effluent toxicity, and thereby reduced the
effectiveness of the RTA test for monitoring ID
refractory toxicity. The existing data on the toxicity of
sewage sludges is not sufficient to determine how
widespread is the occurrence of biomass filtrate
toxicity. The following discussion provides information
on how to proceed, if the POTW biomass filtrate
toxicity presents an interference in the RTA test.
Additional testing was conducted during the Patapsco
TRE to determine if the biomass toxicity interference
could be removed. TIE results found that the effluent
toxicity was caused mainly by non-polar organic
compounds which preferentially adsorb onto sewage
solids. Thus, tests were performed to determine if
solids removal would reduce the Patapsco RAS
toxicity. These tests demonstrated that toxicity in the
RAS coarse filtrate could be removed by filtering the
coarse filtrate through a 0.2 pm pore size filter to
remove colloidal material from the liquid (Botts et.al.,
1987). Alternatively, centrifugation of the coarse
filtrate at 15,000 xg for 10 minutes also substantially
reduced the biomass toxicity. Although biomass
toxicity can be removed by applying these treatment
steps to RTA test effluents, the resulting effluent
toxicity will only indicate the soluble refractory toxicity
of the IU wastewater, instead of the total refractory
toxicity (i.e., soluble and particulate).
Prior to conducting the RTA, aquatic toxicity tests of
the POTW activated sludge should be performed to
determine if the sludge is toxic. This testing involves
filtering the activated sludge through a coarse glass
fiber filter, which is the same type of filter used for SS
analysis, and testing the filtrate toxicity (Mount and
Anderson-Carnahan, 1988a). If the biomass coarse
filtrate is observed to have toxicity that is equal to or
less than that of the POTW effluent, the POTW
biomass can be used in RTA testing. Small particle
filtration or centrifugation of the resulting RTA batch
effluents will not be required.
If the biomass coarse filtrate is observed to be more
toxic than the POTW effluent, the authors suggest the
use of a non-toxic biomass such as another POTW
biomass or a commercially available freeze-dried
preparation. The non-toxic biomass will not be
acclimated to the influent wastewaters of the POTW,
but its use may allow an estimate of the non-
biodegradable toxicity of the sewer discharge. The
authors also recommend that the POTW activated
sludge be used in a parallel series of RTA tests to
determine the amount of soluble refractory toxicity in
the sewer wastewater. The use of toxic POTW
biomass is suggested because it is acclimated to the
5-4
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Table 5-1. Tier I - Refractory Toxicity Assessment
Biomass Toxicity Measurement: • • •_" • -» , .
* Collects liters of fresh return activated sludge (HAS) and aerate vigorously for 15 minutes.
• Prepare glass fiber filter [same type used for SS analysis (APHA, 1985)] by rinsing two 50 ml volumes of high purity water through
the filter. . . ^r-j M
• Filter RAS to.yield 200 ml of filtrate."
• Test RAS filtrate for acute toxicity using the procedure described by Mount and Anderson-Carnahan (1988a) or for chronic toxicity
using the methods provided by Horning and Weber (1985).
• Repeat above steps on several RAS samples.
• If RAS filtrate is more toxic than the POTW effluent, obtain non-toxic biomass (e.g., another POTW biomass or a freeze-dried
preparation)
Sample Collection (volumes based on single sewer sample):
• Obtain 24-hour composite samples of sewer discharge (i.e., IU effluent or sewer line wastewater) and POTW primary effluent Lag
collection of primary effluent sample by the estimated travel time of sewer wastewater to POTW. .
• Refrigerate 6 liters of sewer sample at 4°C until use. Determine the maximum holding time by measuring sample toxicity over time
using methods described by Mount and Anderson-Carnahan (1988a). . . . ,
• Refrigerate 5 liters of primary effluent sample at 4°C'until use. Determine the maximum holding time as described above.
• Hold 3 liters of tap water for 2 days to dissipate chlorine. • ;" •
• Collect 10 liters of RAS (and non-toxic biomass) on day of test and aerate vigorously for 15 minutes before use.
Sample Characterization (performed on day of sample collection):
• Analyze sewer wastewater for TKN, TP, TDS, COD, SCOD, pH.
• Use historical ratio of COD/BOD5 of sewer wastewater, if available, to estimate BOD5.
• Prepare glass fiber filter as stated above. Filter RAS to yield 200 ml of filtrate." Test filtrate for acute toxicity (Mount and Anderson-
Carnahan, 1988a) or chronic toxicity (Horning and Weber, 1985). :.'
• Determine percent volume of sewer wastewater in POTW influent based on flow data.
Sample Preparation: . ,
• Add nutrients to sewer sample to adjust BOD5/TKN/TP ratio to 100:5:1.
• Adjust pH of sewer sample to average pH value of POTW influent.
• Test sample toxicity (Mount and Anderson-Carnahan, I988a) after nutrient addition and pH adjustment to determine if'these steos
affect the sample toxicity. H
Preparation of Batch Test Mixtures (three to six batch tests):
• Warm all refrigerated samples to room temperature using 30°C water bath. Do not overwarm. .-•• .
« Select volume of RAS (VB) to yield a MLSS concentration in 1.5 liters of batch mixture that is equal to the average POTW MLSS
If RAS is toxic (i.e., more toxic than POTW effluent), also select appropriate volume of nontoxic biomass (VNB). , .' •
• Add RAS volume (VB) to three 2-liter beakers, add diffused air (use air stone), and gently aerate. If RAS is toxic (i e more toxic
than POTW effluent), add nontoxic biomass (VNB) to three additional beakers and aerate.
e Prepare 2 liters of synthetic wastewater solution using stock synthetic wastewater (Table 5-2) and the tap water Add volume of
stock that will yield a solution COD equal to the primary effluent COD. Measure acute toxicity of the synthetic solution using the
procedure described by Mount and Anderson-Carnahan (1988a). Chronic toxicity can be measured using the methods described by
Horning and Weber (1985). ,
• Measure sewer sample volume (VW) that will yield a percent volume in 1.5 liters equal to 10 times the nominal percent volume of
:-.. sewer wastewater in the POTW influent. .
" (continued)"'
5-5
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Table 5-1. Continued
Performance of Batch Tests (total batch volume equals 1.5 liters):
• Add Vw and primary effluent to one beaker containing VB. If RAS is toxic (i.e., more toxic than POTW effluent), also add Vw and
primary effluent to one beaker containing VNB.
• Add Vw and synthetic wastewater to one beaker containing VB. if RAS is toxic (i.e., more toxic than POTW effluent), also add Vw
and synthetic wastewater to one beaker containing VNB.
• Add primary effluent to one beaker containing VB. If RAS is toxic (i.e., more toxic than POTW effluent), also add primary effluent to
the remaining beaker containing VNB.
• Adjust aeration rate to allow complete mixing in all batch reactors. Periodically check DO level and maintain DO above 2 mg/l.
• Calculate the required reaction period necessary to achieve a batch F/M ratio (F/MB) equal to the nominal F/M ratio (based on
SCOD) in the POTW.
• Periodically check the batch reactor pH. Adjust pH to 6-9 range, if necessary.
• Note: batch tests should be performed at room temperature.
Effluent Toxicity Analysis:
• Slop aeration after the required reaction period and allow the VB (and VNB) to settle for 15 minutes.
• Decant 200 ml of clarified batch supernatant from each beaker. Rinse glass fiber filters as stated above. Filter each batch
supernatant using separate filters.* Wash filter apparatus between each sample filtration using 10% HNO3, acetone and high purity
water.
• Batch filtrates that were treated with toxic biomass (VB) must be either filtered through prewashed 0.2 pm glass filters or
contnfuged at 10,000 xg for 10 to 15 min to remove colloidal size particles. Viscous mixtures may require faster or longer
contnfugation (ASM, 1981).
• Prepare filter blanks for each filter type using dilution water from toxicity test procedure.
• Analyze the batch filtrates, centrates, and filter blanks for acute toxicity using the procedure described by Mount and Anderson-
Carnahan (1988a). Chronic toxicity can also be measured (Horning and Weber, 1985)
'Note: Positive pressure filtering is required. Also, note that chronic toxicity measurement will require larger filtrate volumes as described by
Horning and Weber (1985).
POTW influent wastewaters and will therefore provide
a level of batch treatment that is more similar to the
treatment efficiency of the POTW than that of the
unacclimated alternate biomass. In this case, small
particle filtration or centrifugation is required to
remove the interfering biomass particles. By
performing RTA tests with POTW biomass in parallel
with RTA tests with alternate biomass, both the
soluble and total refractory toxicity of the ID
wastewater may be estimated.
Sample Collection
Wastewater and activated sludge samples should be
collected according to the procedures described in
Section 13. Return activated sludge (RAS) is
recommended for use in batch testing, because it is
in a concentrated form that can be easily diluted to
the correct MUSS concentration. Mixed liquor from
the POTW's aeration basins can be used in lieu of
RAS; however, the activated sludge will need to be
thickened to the same SS concentration as that of the
RAS before use.
Sample Characterization and Preparation
The sewer sample should be analyzed for total and
soluble COD, total kjeldahl nitrogen (TKN), total
phosphorus (TP), total dissolved solids (TDS) and pH
on the day of sample collection. An estimate of the
sample BOD5 can be calculated using historical data
on the COD/BOD5 ratio of the wastewater. Based on
these results, the BOD5/TKN/TP concentration ratio
of the sewer sample should be adjusted, if necessary,
to 100:5:1 which is the typical ratio for municipal
sewage. This BODs/TKN/TP ratio will ensure that
sufficient nutrients are available for consistent batch
treatment of the IU wastewaters. Phosphorus should
be added in the form of three parts KH2PO4 to four
parts «2HPO4. Nitrogen should be added as urea
nitrogen.
Following nutrient addition, the pH of the sewer
sample should be adjusted to the average pH value of
the POTW influent. Sulfuric acid and sodium
hydroxide can be used for pH adjustment.
Following nutrient addition and pH adjustment, the
sewer sample toxicity should be measured to
determine if the nutrients or pH adjustment cause a
change in sample toxicity. Substantial differences
between the initial toxicity and the adjusted sample
toxicity may indicate the presence of specific types of
toxicants. A discussion of the use of pH adjustment
5-6
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for toxicity characterization is given by Mount and
Anderson-Carnahan (1988a).
Preparation of Batch Test Mixtures
The volume of RAS biomass (Ve), to be used in
batch testing, should yield a batch MLSS
concentration that is equal to the average MLSS
concentration in the POTW aeration basins. The
amount of RAS to be added to the total batch volume
of 1.5 liters is calculated as follows:
_ POTW MLSS
B ~ RAS SS
xl.5 liters.
The same equation is used to determine the alternate
(non-toxic) biomass volume
A total of three batch influent solutions are prepared
for each sewer sample: sewer sample spiked into
synthetic sewage, sewer sample spiked into POTW
influent (primary effluent) and primary effluent alone.
The synthetic wastewater provides a standard non-
toxic substrate that will allow consistent batch
treatment of the ID wastewaters and will permit a
determination of the refractory toxicity of the IU
wastewaters. The composition of this synthetic
wastewater reflects the soluble COD (SCOD) and
nutrient content of typical domestic sewage (Table
5-2). Similar synthetic preparations have been used
as supplements in biodegradation studies (Kirsh et.al.,
1 985) in lieu of domestic sewage.
Table 5-2. Synthetic Wastewater Composition*
Constituent
Concentration (g/l)
Bacto Peptone
Beef Extract
Urea
NaCI
CaCI2»2 H2O
MgSO4.7 H2O
KH2PO4
K2HPO4
32.0
22.0
6.0
1.4
0.8
0.4
3.5
4.5
'SCOD of the stock solution is 64,000 mg/l.
Prior to use in RTA testing, the synthetic wastewater,
which has an SCOD of 64,000 mg/l, is diluted in
dechlorinated tap water. The synthetic wastewater
should be diluted to an SCOD concentration that is
equal to the average SCOD concentration of the
POTW primary effluent. The required stock synthetic
wastewater volume can be calculated as follows:
Stock Synthetic Wastewater Volume =
Primary Effluent SCOD
64,000 mg/l SCOD
xl.5 liters
The amount of sewer sample to be used in batch
testing should reflect the percent volume of sewer
wastewater in the POTW influent. In some cases, the
toxicity in sewer wastewater from small contributors
may not be readily observed when the wastewater is
mixed by percent volume with synthetic wastewater
or POTW influent. Thus, the authors recommend
using a volume of sewer wastewater (Vw) equal to
ten times the percent volume of sewer wastewater
typically found in the POTW influent. For example, if
the sewer wastewater flow is 0.5 mgd and the POTW
influent flow is 50 mgd, Vw would equal 10% of the
batch influent solution. In cases where the sewer
wastewater flow is > 10% of the POTW influent flow,
the sewer sample would comprise 100% of the batch
influent.
Performance of Batch Tests
In the batch tests, the sample/synthetic solution is
used to measure the refractory toxicity of the sewer
sample. The sample/primary effluent solution provides
an indication of the interactive effects (e.g., additive
or antagonistic) that can occur when the sewer
wastewater and POTW influent are combined. The
third batch solution, primary effluent, serves as a
control for the sample/primary effluent test by
providing a measure of refractory toxicity in the
primary effluent.
The batch influent solutions are mixed with RAS (VB)
to yield a total batch volume of 1.5 liters and diffused
air is applied to the mixture. The diffused aeration
must be performed in appropriate laboratory fume
hoods to prevent exposure of laboratory staff to any
toxic vapors stripped from the wastewater samples
(Section 11 ).The aeration rate is adjusted to ensure
complete mixing in the batch reactor and to maintain
a DO concentration above 2 mg/l.
The organic loading to the batch reactors can vary
substantially depending on the type of sewer
wastewater being tested. To allow comparable
treatment of the various sewer wastewaters, the
food-to-microorganism ratio of the batch reactor
(F/MB) can be standardized by varying the time of
aeration. F/MB should be made equal to the F/M
(based on SCOD) of the POTW bioreactors. The
required batch test period can be calculated as
follows:
^ *D • JfJ •, Batch InfluentSCOD(mg/Q
Test Period (days) = :
MLVSS(mg/l)xF/M
.B
5-7
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A typical test period for a sewer sample with COD
< 1000 will be appropriately 2 to 4 hours.
Toxlcity Measurement
Either acute or chronic refractory toxicity can be
measured in RTA testing. Procedures for acute
toxicity measurement should follow the methods
described by Mount and Anderson-Carnahan
(1988a). In order to obtain comparable acute toxicity
results, RTA testing should utilize the same species
that was used for TIE tests. Other acute toxicity
analyses such as bacterial bioluminescence tests
(e.g., MicrotoxTM) can be used in conjunction with
the preferred test species to provide additional
information. Chronic toxicity testing should utilize the
same species that was used for TIE testing. Chronic
toxicity test methods are described by Horning and
Weber (1985).
The batch test mixtures are prepared for toxicity
analysis by allowing the mixed liquors to settle,
decanting the clarified supernatant, and filtering the
supernatant through a coarse glass fiber filter. The
coarse filtration step is used to more closely simulate
the POTW clarification process because the batch
settling alone is not as efficient as the POTW settling
process. If toxic biomass is used in the RTA tests,
further particulate removal is required to measure the
soluble refractory toxicity in the sewer wastewater. In
this case, the coarse filtrate can be filtered through a
0.2 um pore size glass filter to remove colloidal size
particles from the wastewater. Membrane filters such
as cellulose nitrate filters are not recommended
because some soluble organic constituents may
adsorb onto the filter. Prior to sample filtration, all
filters should be washed and filter blanks should be
prepared using the steps described in Section 10.
Alternatively, the coarse filtrate can be centrifuged at
10,000 xg for 10 to 15 min to separate colloidal
material from the wastewater (ASM, 1981).
Data Evaluation
Results of RTA testing are used to locate the sources
that are contributing refractory toxicity to the POTW.
A discussion of the evaluation of RTA results is
provided as follows.
Results of RTA Tests if POTW Biomass is Non-
Toxic -
In cases where the POTW biomass filtrate is
determined to have toxicity that is equal to or less
than that of the POTW effluent, RTA tests will utilize
POTW biomass and wastewater samples. Results for
each IU sample analysis will consist of data on three
batch tests: one test of sample/synthetic sewage
solution, one test of sample/primary effluent solution,
and one test of primary effluent. The batch test of the
sewer sample/synthetic wastewater solution reveals
the amount of refractory toxicity in the sewer
wastewater excluding the effects of other influent
wastewaters. Perhaps the most important batch test
is the analysis of the sewer sample/primary effluent
solution, because test data will indicate the toxicity
that would realistically occur upon mixture of the
sewer wastewater with POTW influent. Results of this
combined wastewater test are compared to results of
the primary effluent batch test to determine if
combining the wastewaters decreases the refractory
toxicity (i.e., antagonistic effect) or increases the
refractory toxicity (additive effect) of the primary
effluent.
If the effluent toxicity of the sewer sample/primary
effluent test is greater than the effluent toxicity of the
primary effluent test, the sewer wastewater source
can be presumed to be a contributor of refractory
toxicity. A list of toxic sewer sources should be
prepared for further evaluation. In situations where
sewer line tracking is being conducted, this list can
be compared to a sewer collection system map to
identify possible toxic ID dischargers on the sewer
lines.
Results of RTA Tests if POTW Biomass is
Toxic -
In situations where the POTW biomass filtrate is
found to be more toxic than the POTW effluent, RTA
tests will utilize alternate (nontoxic) biomass and
wastewater in addition to tests with POTW biomass
and wastewater. The data on each IU sample analysis
will consist of results of three batch tests using
alternate biomass (i.e., one test of sample/synthetic
sewage, one test of sample/primary effluent, and one
test of primary effluent); and results of three batch
tests using POTW (toxic) biomass (i.e., using same
wastewaters as above). The results of tests that use
alternate biomass may provide an estimate of non-
biodegradable toxicity of the sewer wastewater. The
disadvantage of these tests is that the biomass is not
acclimated to the POTW influent wastewaters,
therefore the level of toxicity reduction may not reflect
the treatment efficiency of batch tests using the
POTW acclimated biomass. Nonetheless, the non-
toxic biomass tests can give an indication of the
relative level of refractory toxicity being contributed by
the sewer wastewater sources.
Batch tests using toxic POTW biomass better reflect
the treatment efficiency of the activated sludge
process; however, manipulation of the batch effluent
(i.e., centrifugation or small particle filtering) removes
particles that normally are present in the POTW
effluent. Batch effluent treatment is necessary to
remove the interfering toxic biomass, but this
treatment causes artificial changes in the batch
effluent toxicity. The advantage of toxic biomass tests
is that the soluble refractory toxicity of source
5-8
-------
wastewaters can be determined. The nontoxic
biomass tests cannot provide as good an estimate of
soluble toxicity, because this biomass is not
acclimated to the POTW influent wastewaters.
RTA tests which utilize POTW toxic biomass and
alternate biomass can provide information on both the
soluble and total refractory toxicity of the ID
wastewater. Further studies are in progress to
improve the utility of the RTA test for toxicity source
evaluation. These studies will focus on the
development of procedures to account for the toxicity
interferences caused by toxic activated sludge.
RTA Conclusions
If the RTA testing is successful in locating the
sources of refractory toxicity, further testing is
required in Tier II (Section 6) to confirm the
suspected toxic sources. Tier II testing is necessary
because Tier I information is not sufficient to proceed
to the evaluation and selection of pretreatment control
options (Section 8).
In situations where RTA testing proves to be ,a
prodigious task, the permittee may elect to evaluate
alternatives for in-plant toxicity control (Section 7).
This choice may be determined by assessing the best
use of the resources that are available for the TRE. In
this regard the POTW has the option to recover costs
associated with toxicity source evaluation through the
process of local limits development.
•
5-9
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-------
Section 6
Toxicity Source Evaluation - Tier II
Introduction
A Tier II evaluation is conducted to gather additional
information on the indirect dischargers to the POTW
to confirm the suspected sources of toxicity identified
in the Tier I evaluation. Based on the Tier I data,
potentially toxic indirect dischargers are identified and
their wastewaters are sampled and analyzed using
the Tier II Refractory Toxicity Assessment procedure.
Like the RTA step used in the Tier I evaluation, the
Tier II RTA estimates the toxicity that is refractory to
POTW treatment and would therefore be expected to
pass through the POTW. The Tier. II RTA, however,
includes several additional procedures for toxicity
assessment including:
• a series of wastewater dilutions to determine the
concentration of wastewater at which toxicity
pass-through would be expected to occur at
the POTW;
• an optional series of control tests to allow a
comparison of the relative levels of refractory
toxicity and inhibition effects for the various
sewer wastewaters; and
• TIE Phase I tests of toxic batch effluents to
indicate the components of the refractory
toxicity.
A diagram of the Tier II RTA is presented in Figure
6-1. The step by step procedures for implementing
RTA tests are shown in Table 6-1.
The results of the Tier II testing are used to rank
indirect dischargers in terms of their potential to
contribute inhibitory material or refractory toxicity to
the POTW. Results of the optional TIE Phase I
analysis may also provide important information on
the toxic components of the sewer wastewater. The
Tier II data are used to identify the major toxic
dischargers and to evaluate pretreatment options for
controlling the discharge of toxics or toxicity by these
dischargers. In situations where existing pretreatment
regulations (i.e., general, specific or categorical) are
insufficient for the POTW to achieve an acceptable
level of effluent toxicity, the municipality is
encouraged to develop local limits for its sewer users
(USEPA, 19873).
Refractory Toxicity Assessment
The procedures for biomass toxicity measurement,
collection, characterization and preparation of
samples, preparation of batch test mixtures,
performance of the batch test, and batch test toxicity
measurement are similar to those described for Tier I
RTA testing (Section 5). A description of the unique
elements and optional steps in the Tier II RTA
procedures is provided as follows.
Biomass Toxicity Measurement
Results of the biomass toxicity measurement
conducted in Tier I (Section 5) will dictate whether or
not an alternative (nontoxic) biomass will be required
for Tier II testing. If the POTW biomass filtrate was
found to be less toxic than the POTW effluent in Tier
I, only POTW biomass will be used in Tier II tests. If
the POTW biomass filtrate was observed to be more
toxic than the POTW effluent in Tier I, both the POTW
biomass and a non-toxic alternative biomass will be
needed for RTA testing in Tier II.
Sample Collection, Characterization, and
Preparation
The procedures for collection, characterization, and
preparation of samples are the same as those
described in Section 5. Sewer sampling locations for
Tier II testing are the points of discharge of the ID
effluent to the sewer collection system. If sewer line
sampling was conducted in Tier I, sufficient data
should have been collected to identify the lUs to be
sampled for Tier II.
Preparation of Batch Test Mixtures
The steps for determining the volume of biomass
(VB) and the synthetic wastewater concentration to
be used in batch tests are the same as those
described for Tier I RTA testing (Section 5). Because
additional dilutions are performed in Tier II RTA
testing, sufficient biomass and synthetic wastewater
should be prepared for seven batch tests (if the
POTW biomass is non-toxic) or fourteen batch tests
6-1
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Sludge Toxicity
TCLP/EP
Test Wastewater Selected from
Tier I: Toxicity Source Evaluation
Refractory Toxicity Assessment
• Industrial Wastewater
Dilution Series
• Industrial Wastewater Spiked
into Primary Effluent
• Primary Effluent Control
• Synthetic Sewage Control
• Use POTW Acclimated Biomass
(if toxic also use nontoxic
biomass)
• Use Same F/M as POTW
Test Batch Effluents
Toxicity Pass-Through
• Toxicity Test
Inhibition Testing
0 Oxygen Uptake
• COD Uptake
Apply Phase I Toxicity
Characterization on Lowest
IU Wastewater Dilution
Confirm Specific Sources and
Nature of Toxicity/
Interference
Toxicity Control Selection
Figure 6-1. Tier II: toxicity source evaluation (source ranking/pretreatment evaluation).
(if both toxic POTW biomass and non-toxic biomass
must be used).
Additional IU sample dilutions are performed to
determine the wastewater concentration that causes
refractory toxicity to become apparent in the batch
test effluent. Three IU sample volumes are used in
RTA tests: one equivalent to two times the percent
volume of IU wastewater (Vw2) typically found in the
POTW influent; another equal to five times the
percent volume of IU wastewater (Vws) in POTW
influent; and a third equal to ten times the proportion
of IU wastewater (Vwio) in POTW influent. In cases
where the IU discharge flow is >20% of the POTW
influent flow, the Vws and VWIQ wi!l be 100% of tne
batch influent. If this occurs, the sample volumes can
be reduced to allow an appropriate range of sample
dilutions to be tested.
Performance of Batch Tests
Tier II testing utilizes the same three types of influent
solutions applied in Tier I RTA tests: IU sample
spiked into synthetic sewage, IU sample spiked into
POTW primary effluent, and primary effluent alone.
The difference between Tier II and Tier I RTA testing
is that additional dilutions of IU sample are prepared
in Tier II using the synthetic sewage and primary
effluent wastewaters. Also, extra volumes of the batch
influent solutions are prepared and held for
subsequent toxicity measurement.
The batch tests of the three types of influent solutions
provide data on the level of refractory toxicity in the
IU wastewater. The sample/synthetic solution test
indicates the refractory toxicity of the IU wastewater
by itself. The sample/primary effluent solution
6-2
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Table 6-1. Tier II - Refractory Toxicity Assessment
Sample Collection (volumes based on single sewer sample):
• Obtain 24-hour composite samples of IU discharge arid POTW primary effluent. Lag collection of primary effluent sample by the
estimated travel time of ID wastewater to POTW.
• Refrigerate 18 liters of sewer sample at 4°C until use. Determine the maximum holding time by measuring sample toxicity over time
using methods described by Mount and Anderson-Carnahan (1988a).
« Refrigerate 12 liters of primary effluent sample at 4°C until use. Determine the maximum holding time as described above.
• Hold 9 liters of tap water for 2 days to dissipate chlorine.
• Collect 10 liter grab sample of fresh return activated sludge (RAS) (and non-toxic biomass) on day of test and aerate vigorously for
15 minutes before use.
Sample Characterization (performed on day of sample collection):
Analyze sewer wastewater for TKN, TP, TDS, COD, SCOD, and pH.
Use historical ratio of COD/BOD5 of sewer wastewater, if available, to estimate BOD5.
Determine percent volume of sewer wastewater in POTW influent based on flow data.
Prepare glass fiber filters [same type used for SS analysis (APHA, 1985)] by rinsing two 50 ml volumes of high purity water through
each filter. Filter 200 ml aliquots of samples of IU wastewater, primary effluent and RAS." Wash filter apparatus between each
sample filtration using 10% HNO3, acetone, and high purity water.
Test the filtrates of the IU wastewater, primary effluent and RAS for acute toxicity (Mount and Anderson-Carnahan, I988a) or
chronic toxicity (Horning and Weber, 1985).
P
Sample Preparation:
• Add nutrients to IU sample to adjust BOD5/TKN/TP ratio to 100:5:1.
• Adjust pH of IU sample to average pH value of POTW influent.
• Test sample toxicity (Mount and Anderson-Carnahan, 1988a) after nutrient addition and pH adjustment to determine if these steps
affect the sample toxicity.
Preparation of Batch Test Mixtures (seven to fourteen batch tests):
• Warm all refrigerated samples to room temperature using 35°C water bath. Do not overwarm.
• Select volume of RAS (VB) to yield a MLSS concentration in 1.5 liters of batch mixture that is equal to the average POTW MLSS.
If RAS is toxic (i.e., more toxic than POTW effluent), also select appropriate volume of non-toxic biomass (VNB).
• Add RAS volume (VB) to seven 2-liter beakers, add diffused air (use air stone), and gently aerate. If RAS is toxic (i.e., more toxic
than POTW effluent), add non-toxic biomass (VNB) to seven additional beakers and aerate.
• Prepare 2 liters of synthetic wastewater (Table 5-2) using the tap water. Add volume of stock that will yield a solution COD equal to
the average primary effluent COD. Measure acute toxicity of synthetic solution (Mount and Anderson-Carnahan 1988a). Chronic
toxicity (Horning and Weber, 1985) can also be measured.
• Measure IU sample volumes that will yield a percent volume in 1.5 liters equal to 2, 5, and 10 times the nominal percent volume of
IU wastewater in the POTW influent (VW2, VW5, VW10, respectively)
Performance of Batch Tests (total batch volume equals 1.5 liters):
•••- Mix VW2 and primary effluent (allow for excess of 200 ml). Add this mixture to one beaker containing VB. Keep the remaining 200
, ml. If RAS is toxic (i.e., more toxic than POTW effluent), also add additional VW2 and primary effluent mixture to one beaker
containing VNB. Repeat these steps for VW5 and VW10.
•: Mix VW2 and synthetic wastewater (allow for excess of 200 ml). Add this mixture to one beaker containing VB. Keep the remaining
200 ml. If RAS is toxic (i.e., more toxic than POTW effluent), also add additional VW2 and synthetic wastewater mixture to one
beaker containing VNB. Repeat these steps for VW5 and VW10.
• Add primary effluent to one beaker containing VB. If RAS is toxic (i.e., more toxic than POTW effluent), also add primary effluent to
remaining beaker containing VMB.
Adjust aeration rate to allow complete mixing in all batch reactors. Periodically check DO level and maintain DO above 2 mg/l.
Calculate the required reaction period necessary to achieve a batch F/M ratio (FMB) equal to the nominal F/M ratio (based on
SCOD) in the POTW.
•Periodically check batch reactor pH. Adjust pH to 6-9 range, if necessary.
Note: batch tests should be performed at room temperature.
*-'- ' ' (continued)
6-3
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Table 6-1. Continued
Inhibition Testing (optional - two additional batch tests).
• Prepare two synthetic wastewater solutions using stock synthetic wastewater (Table 5-2) and tap water: one with an SCOD
concentration equal to the average primary effluent SCOD and another with an SCOD level equal to that of the lowest sample
dilution (i.e., VWio spiked into primary effluent).
• Add synthetic wastewater solutions to beakers containing VB- If RAS is toxic (i.e., more toxic than POTW effluent), also add
synthetic solutions to beakers containing VNB-
• Perform batch tests in parallel with above batch tests.
• Subsample 300 ml from all batch reactors at 30 min. and every 2 hours following test initiation, and at the completion of the test.
Upon subsample collection, immediately measure OUR using the BOD bottle method (APHA, 1985). Return the subsamples to
the reactors immediately following use.
• Subsample 50 ml from all batch reactors at 5 minutes and ever 2 hours following test initiation, and at the completion of the test.
Subsample SO ml of the original undiluted biomass stock. Filter the subsamples through a 0.45 u,m pore size filter. Measure the
SCOD of the filtrates.
Toxicity Analysis:
• stop aeration after the required reaction period and allow the VB (and VNB) to settle for 1 5 minutes.
• Decant 200 ml of clarified batch supernatant from each beaker. Prepare filters as described above. Filter the batch supernatants.*
Rinse filtration equipment between sample filtrations as stated above.
• Batch filtrates that were treated with toxic biomass (VB) must be either filtered through prewashed 0.2 pm glass filters or
centrifuged at 10,000 xg for 10 to 15 min to remove colloidal size particles. Viscous mixtures may require faster or longer
centrifugation (ASM, 1981).
• Prepare filter blanks for each filter type using dilution water from toxicity test procedure.
• Analyze the untreated solutions (batch influent), batch effluent and filter blanks for acute toxicity (Mount and Anderson-
Carnahan, 1988a) or chronic toxicity (Horning and Weber, 1985).
Phase I Toxicity Characterization (Optional)
• The batch effluent of the Vwio/synthetic wastewater test should be used for Phase I analysis. Phase I testing requires 3.5 liters
for analysis, therefore the volume used in batch testing should be increased to a minimum of 7 liters.
• Following batch treatment, allow the VB (and VNB) to settle for 1 hour. Decant 3.5 liters of supernatant.
• Prepare coarse glass filters (SS type only) as described above. Filter the batch supernatant.*
• Analyze the batch effluent using the Phase I protocol (Mount and Anderson-Carnahan, I988a).
"Note: Positive pressure filtering is required. Also note that chronic toxicity measurement will require larger sample volumes as described
by Horning and Weber (1985).
provides information on the possible interactive
effects (e.g., antagonism, additivity) that may occur
upon mixture of the ID wastewater and the POTW
influent. The third batch influent, primary effluent,
serves as a control for the sample/primary effluent
test by providing data on the refractory toxicity of the
primary effluent alone.
Following mixture of the batch influents with the
biomass, the mixed liquors are aerated for a period of
time that will allow comparable treatment of the
sample dilutions. Because the organic loading to the
batch reactors can vary depending on the sample
concentration, the F/MB should be standardized by
varying the time of aeration for each sample dilution.
The procedure for calculating the required reaction
period based on F/MB is described in Section 5.
Inhibition Testing (Optional)
Biological treatment inhibition can be assessed by
monitoring substrate (COD) removal and oxygen
uptake rates in the batch tests and comparing the
results of the IU sample batch tests to the results of
the synthetic wastewater batch tests. If COD or
oxygen removal rates in ID sample tests are lower
than those in synthetic wastewater tests, biological
inhibition is indicated.
Inhibition testing requires two additional batch
reactors consisting of synthetic sewage and biomass:
one with a synthetic sewage SCOD concentration
equal to the average primary effluent SCOD and
another with a synthetic sewage SCOD concentration
equal to the SCOD level of the lowest IU sample
6-4
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dilution (i.e., Vwio spiked into primary effluent). The
two synthetic wastewater concentrations effectively
bracket the highest and lowest expected SCOD
loadings to the batch reactors. This range of synthetic
sewage concentrations is necessary to compare COD
and oxygen removal rates for the wastewater
dilutions, because COD and oxygen utilization usually
increase with increasing wastewater strength. At high
soluble substrate concentrations (i.e., 1 mg/l SCOD to
4 mg/l MLVSS) the biomass activity generally reaches
a maximum rate. At soluble substrate concentrations
below this "plateau," biomass activity rates vary with
substrate concentration. Thus, the soluble substrate
concentrations of the ID sample tests and the
synthetic sewage tests must be similar to allow an
accurate comparison of COD and oxygen utilization
rates for inhibition measurement.
Soluble COD removal can be used as an indicator of
specific substrate removal rate (SSUR). SSUR is
reported in units of mg/l SCOD/g MLVSS/min, and is
calculated as shown in an equation at the end of this
page.
The POTW biomass used in batch testing contains
nonbiodegradable SCOD remaining from biological
treatment which must be accounted for when
calculating the SCOD of the batch effluent. This
correction for biomass SCOD is calculated as shown
in an equation at the top of the next page.
Specific oxygen uptake rate (SOUR) is reported in
units of mg 02/l/g MLVSS/min and is calculated as
follows:
SOUR =
Oxygen Consumed
MLVSS xD.O. Measurement Period (min)
The SSUR and SOUR data for the IU sample dilution
series and the two synthetic sewage tests are plotted
against the SCOD of the batch influent solutions. A
reduction in the SSUR and SOUR rates of the IU
sample tests relative to the SSUR and SOUR rates of
the synthetic control tests (for samples with
equivalent batch influent COD concentrations)
indicates the presence of inhibitory material in the IU
wastewater. The degree of inhibition can be inferred
by the amount of deviation in the biomass activity
rates for IU sample tests compared to the biomass
activity rates for the control rates.
Toxicity Analysis
The procedures for acute and chronic toxicity
measurement of the RTA samples are the same as
those described for Tier I (Section 5). In addition to
the batch effluent samples, the batch influent
solutions are measured for toxicity.
Phase I Toxicity Characterization
Phase I tests can be applied to the batch effluent of
the lowest dilution of the sewer wastewater in
synthetic sewage (i.e., highest wastewater strength).
. The purpose of this analysis is to determine the types
of toxicants causing refractory toxicity in the IU
wastewater. Results of Phasp I testing can be
compared to TIE results on the POTW effluent to
indicate whether or not the IU wastewater contains
refractory toxicants that were also observed in the
POTW effluent. A description of the Phase I
procedure is given in Section 4.
Data Evaluation
Results of the Tier II evaluation are used to confirm
the sources of the refractory toxicity identified in Tier
I. Tests of the series of dilutions of the IU wastewater
samples can indicate the wastewater concentration at
which toxicity passthrough would be expected to
occur at the POTW. This information can be used to
identify the major contributors of refractory toxicity to
the POTW.
Results of RTA Tests if POTW Biomass is Non-
Toxic --
In cases where the POTW biomass filtrate is
determined to be less toxic than the POTW effluent,
RTA tests will utilize POTW biomass and wastewater
samples. Results for each IU sample analysis will
consist of data on seven batch tests: three tests of
sample/synthetic sewage dilutions, three tests of
sample/primary effluent dilutions, and one test of
primary effluent.
Sample/synthetic sewage tesf--The batch tests of
the series of IU sample/synthetic sewage dilutions;will
reveal the IU wastewater concentration that causes
toxicity to occur in the batch effluent. For example,
batch effluent toxicity may become apparent in tests
of IU wastewater at sample concentrations five times
the wastewater concentration (Vws) typically
observed in the POTW influent, but not at sample
concentrations two times the typical wastewater
concentration (Vw2)- In this case toxicity pass-
through occurred somewhere between two and five
times the IU wastewater concentration typically "found
in the POTW influent.
Batch Influent SCOD (mg/l) - Batch Effluent SCOD (mg/l)
oo UK = — ——•
MLVSS (mglt) x Test Period (min)
6-5
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SCOD =
[ (VJx (SCOD Batch Reactor Effluent)] - [ (VJ x SCOD biomass)]
K o
where VR is the total volume in the batch reactor,
and VB is the volume of RAS added to the reactor.
The relative amounts of refractory toxicity contributed
by the IDs can be determined by accounting for the
discharge flow of each of the tested IDs. The first
step is to convert the 48-hour LCso values for each
sample dilution to toxic units (TU) by multiplying the
reciprocal of each LCso value by 100 (i.e., 100/LCso).
The toxic units for each sample dilution series are
then summed and the total toxic units are multiplied
by the flow rate of the IU discharge. An example
calculation is described below.
Sample Dilution
(Times Percent Flow in
POTW Influent)
Batch effluent LCSO
(as percent effluent):
Batch effluent toxic units
2X
50
5X
30
3.3
10X
10
10
Relative Score s Sum of TUs x IU Discharge Flow Rate,
where sum TU ** 15.3, and
IU Discharge Flow Rate = 1 mgd.
Thus, the ID relative score is:
15.3 TU x 1 mgd = 15.3 TU - million gal/day.
The relative scores of the IU wastewaters are ranked
to determine the major contributors of refractory
toxicity. Although the relative score is in units of TU-
million gal/day, it does not represent the actual
toxicity loading of the IU wastewater. Instead, the
relative score is an estimate for comparing the
relative levels of refractory toxicity contributed by the
lUs.
Samplefprimary effluent fesfs—Resuits of the batch
tests of the series of IU sample/primary effluent
dilutions will indicate the IU wastewater concentration
that causes refractory toxicity to occur upon mixture
of the wastewater with POTW influent. These tests
are an attempt to measure the effects of mixing the
IU wastewater with the POTW influent wastewater, as
would realistically take place in the POTW influent.
Combining the wastewaters may decrease the
refractory toxicity (i.e., antagonistic effect) or increase
the refractory toxicity (i.e., additive effect) of the IU
wastewater.
The relative level of refractory toxicity contributed by
the lUs can be determined by calculating a relative
score using the batch effluent LCso f°r each IU
sample as described above. This relative score will
account for the antagonistic or additive toxic effects
VR
that may occur upon mixture of the IU wastewater
with the POTW influent. Relative scores for the lUs
can be ranked to identify the major contributors of
refractory toxicity.
The ranking of lUs based on the IU sample/primary
effluent tests is preferred over the IU ranking based
on the IU sample/synthetic sewage tests, because the
IU wastewater/primary effluent mixture better reflects
the composition of the POTW influent. The IU ranking
can be used to determine which major toxic
dischargers should be targeted for pretreatment
control.
Results of RTA Tests if POTW Biomass is
Toxic —
In situations where the POTW biomass filtrate is
found to be more toxic than the POTW effluent, RTA
tests will utilize alternate (non-toxic) biomass and
wastewater in addition to tests with POTW biomass
and wastewater. The data on each IU sample analysis
will consist of results of seven batch tests using
alternate biomass (i.e., three tests of sample/synthetic
sewage dilutions, three tests of sample/primary
effluent dilutions, and one test of primary effluent) and
results of seven batch tests using POTW biomass
(i.e., using same wastewaters as above). The batch
effluent results of tests using POTW biomass will
indicate soluble refractory toxicity, because the toxic
biomass particles are removed (via filtration or
centrifugation) prior to toxicity analysis. Batch
effluents of tests using alternate biomass do not
require treatment for toxic particle removal, therefore,
the batch effluent results will reveal the total
refractory toxicity of the IU wastewater.
Batch tests using POTW to/omass--Batch tests
which utilize POTW (toxic) biomass will provide an
indication of the soluble refractory toxicity of the IU
wastewater. The relative contribution of soluble
refractory toxicity from the lUs can be determined by
calculating relative scores for the IU sample/synthetic
sewage dilution tests and the IU sample/primary
effluent dilution tests.
Batch tests using alternate b/omass--Batch tests
that utilize an alternate (non-toxic) biomass provide
data on the total refractory toxicity (i.e., soluble and
particulate) of the IU wastewater. These tests are an
indirect measure of refractory toxicity because an
alternate biomass is not acclimated to the POTW
influent wastewaters and the level of toxicity reduction
that can be achieved by an unacclimated biomass will
not be the same as that achieved by POTW
acclimated biomass. In some cases, the batch
6-6
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influent may partially or completely inhibit toxicity
degradation when unacclirhated biomass is used.
Nonetheless, batch tests utilizing alternate biomass
may give a relative estimate of, the level of total
refractory toxicity contributed by Ills. The relative
contribution of refractory toxicity from the ILJs can be
determined by calculating relative scores for the IU
sample/synthetic sewage dilution tests and the ID
sample/ primary effluent dilution tests.
Toxicity measurement of batch influent
so/uf/ons--The batch influent solutions are also
measured for toxicity to provide information on the
toxicity of the raw (untreated) IU wastewater. This
information can be used together with the batch
effluent data on soluble and total refractory toxicity to
identify the major toxic IDs.
Results of Optional Inhibition Testing -
The optional analyses for wastewater inhibition can
also provide useful data. RTA information on the
potential for a wastewater to inhibit biomass activity
can be used ,to identify III wastewaters that may
interfere with the POTW biological treatment process.
This information is important in situations where
inhibitory wastewater may interfere with the normal
operation of the biological treatment process to the
degree that it causes toxicity passthrough.
Results of Optional TIE Phase I Testing -
Phase I analysis of the batch treated wastewater can
indicate the types of toxicants responsible for the
refractory toxicity in the IU wastewater. A comparison
of these Phase I results with the results of the TIE
analysis of the POTW effluent will indicate whether or
not the IU wastewater toxicants are the same types of
toxicants observed in the POTW effluent. lUs which
discharge the same types of toxicants as those found
in the POTW effluent should, be candidates for
pretreatment control evaluation.
Pretreatment Control Evaluation
Pretreatment control options can be developed by the
POTW to prevent the pass-through of toxics and
toxicity, and treatment interferences, which have been
traced to indirect dischargers. In cases where current
pretreatment regulations are insufficient for the POTW
to achieve an acceptable level of effluent toxicity, the
municipality should develop local limits for its sewer
users (USEPA, 1987a).
The EPA Local Limits Guidance Manual (USEPA,
1987a) describes several technical approaches to the
development of local limits. These approaches are
outlined as follows:
• Allowable Headworks Loading Method:
Numeric limits are defined based on the
maximum loadings of pollutants that will allow
compliance with receiving water quality
criteria or sludge quality criteria, or protection
against treatment interferences.
• Industrial User Management Method: .Based
on an in-depth review of IU practices the
municipality can set narrative limits for
chemical management practices (e.g.,
chemical substitution, spill prevention and
slug loading control).
• Case by Case Permitting: Technology-based
limits are established based on levels that can
be feasibly and economically achieved by
comparable industries.
Some of the local limits approaches address specific
issues of concern related to toxics or toxicity. For
example, the allowable headworks loading method is
well-suited for developing limits to prevent the
pass-through of toxic compounds identified by Tier I
chemical-specific analysis or by POTW effluent TIE
tests. This method can be used to establish the
maximum level of the toxic pollutant that can be
safely received by the POTW without exceeding the
effluent toxicity limit.
The industrial user management method provides a
framework for implementing chemical management
practices including slug discharge control. In cases
where IU slug loadings contribute to POTW effluent
toxicity, spill prevention or load equilization can be
implemented at the IU facility to moderate the slug
loadings. EPA's Slug Loading Control Manual (1988b)
describes methods for the development of slug
loading control programs.
The case by case permitting method can be used
when the POTW effluent toxicity cannot be traced to
specific IU chemicals, but information on the general
classes of toxicants is available based on TIE results.
In this case an engineering decision can be made in
selecting a pretreatment technology for removing
general types of toxicants (i.e., non-polar organic
compounds). In situations where the sources of
toxicity have been identified, the POTW has the
authority to require the IU to take steps to limit ,the
discharge of refractory or inhibitory toxicity.
Although EPA and the states have overview authority,
the choice of which technical approach to use for
local limits development is the POTW's decision. The
information to be used in the development of local
limits will include the data gathered in the TIE and
toxicity source evaluations (Tier I and II). Methods for
calculating numerical limitations and preparing
narrative limitations are described in the EPA Local
Limits Guidance Manual (USEPA, 1987a). The goal in
developing local limits is to implement pretreatment
regulations that are technically and legally defensible.
The local limits can include provisions for equitable
recovery of costs associated with the toxicity source
evaluations and local limits development.
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Section 7
POTW In-Plant Control Evaluation
Introduction
The objective of the in-plant control evaluation is to
select and evaluate feasible treatment options for the
reduction of refractory toxicity and/or toxic
interferences at the POTW. Treatment options are
selected using the data gathered in the PPE (Section
3) and TIE (Section 4) investigations and best
professional judgement. Following this selection
process, treatability testing is conducted to determine
the toxicity removal effectiveness and operating
characteristics of the treatment options. The resulting
test data provide a basis for the final selection and
conceptual design of feasible POTW process
modifications or additions.
A schematic of the POTW in-plant control evaluation
is presented in Figure 7-1. Toxicity control options
are selected based on evidence that the options are
technically feasible and can be integrated into the
overall design of the treatment facilities. Following
selection, the options are evaluated in bench-scale
tests which utilize acute or chronic toxicity tests or
toxic chemical analyses to evaluate the feasibility of
the option for toxicity and/or toxics reduction. In some
cases, pilot-scale testing may be conducted to
provide information for the design of the treatment
option. An optional TIE Phase I analysis may be
performed to evaluate the removal of selected
toxicants by the treatment option.
It is important to consider that major changes in
treatment plant facilities or operations may not be
feasible due to the cost of new facilities or the
complexity of additional process operations. In these
situations, pretreatment control of toxicity may be
preferred to in-plant control.
Selection of Treatment Options for
Testing
The information collected in the PPE and TIE stages
of the TRE is reviewed and evaluated to select
possible feasible in-plant options to be tested in
treatability studies. The first step in the selection
process is to review the PPE data on the POTW
design to establish the physical space available for
Select
Treatment
Options for
Testing
Sludge
Bench Scale or Pilot Scale
Treatability Test
Test Modification of Existing
Process or Evaluate
Additional Process
Effluent
Toxicity Pass-
Through and/or
.Interference
(Optional)
Phase I Toxicity
Characterization
Toxicity Control Selection
Figure 7-1. POTW in-plant control evaluation.
new process additions and to determine the idle
facilities and equipment that could be used for toxicity
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control. In addition, information on POTW operations
and maintenance should be reviewed to determine if
the POTW is capable of meeting the increased
operational control that may be required with process
modifications or additions. This PPE information can
be compared to the TIE data to identify potential
control options, and to determine how the control
options can be integrated into the overall treatment
system design.
Secondly, TIE Phase I data on the classes of effluent
toxicants can be used to select options to be
examined. For example, if non-polar organic
compounds are frequently observed to be the
principal effluent toxicants, possible options would
include granular media filtration, activated carbon
adsorption, or coagulation and precipitation. TIE
results on specific effluent toxicants, which have been
identified and confirmed in Phases II and III, can also
be used to determine possible in-plant control
options. Although results on specific toxicants are well
suited for the application of pretreatment control
limitations, the municipality may choose to evaluate
in-plant control of these toxicants. An example of
this case is the treatment of ammonia by optimizing
the POTW activated sludge process (e.g., increase
MCRT) to achieve nitrification. Wherever possible, the
in-plant control evaluation should be performed in
conjunction with the pretreatment control evaluation
to identify the most technically feasible and cost-
effective control option.
In-plant toxicity control may be achieved by
enhancement of the existing treatment system or by
the implementation of additional treatment processes.
Possible in-plant control alternatives for different
categories of toxic compounds are summarized in
Table 7-1. A description of these control alternatives
is provided as follows.
Process Enhancement
Biological Process Control
Biological process control is generally limited to
activated sludge systems, although some
modifications to fixed film processes (e.g., trickling
filters and rotating biological contactors) may be
feasible. The performance of activated sludge
systems is generally controlled by adjusting one or
more of three process parameters: mean cell
residence time, mixed liquor suspended solids and
food-to-microorganism ratio. The treatment
efficiency of the activated sludge system, and the
activated sludge characteristics, are controlled by
varying these interrelated process parameters. A
description of the use of these parameters for toxics
control is provided as follows.
Mean Cell Residence Time -
Removal of biodegradable toxic compounds in
activated sludge treatment may be improved by
increasing the MCRT (Adams et.al., 1981). MCRT
can be increased by lowering the excess sludge
wasting rate. Longer MCRTs result in an increased
sludge age which can be beneficial for the
biodegradation of some types of organic compounds.
Mixed Liquor Suspended Solids -
High MLSS concentrations have been shown to
minimize the effects of inhibitory pollutants on
activated sludge treatment systems (WPCF, 1976).
High MLSS concentrations increase the potential for
biodegradation and sorption of toxic wastewater
constituents, and can aid in protecting the treatment
process from shock loadings.
Food-to-Microorganism Ratio —
A decrease in F/M (based on BODs) effectively
decreases the organic waste loading per unit of
biomass which may improve the biodegradation of
toxic compounds (Adams et.al., 1981). The F/M ratio
is inversely related to MCRT and is an alternative
parameter for controlling activated sludge treatment.
Biological process control is not as easily
accomplished for fixed film processes, such as
trickling filters or RBCs. Some adjustments can be
made, however, such as varying the amount and
point of wastewater recirculation in a trickling filter, to
increase the removal of toxic pollutants. In addition,
secondary clarifier effluent can be recirculated to
dilute high-strength wastes prior to treatment in a
trickling filter or RBC. In some cases inhibitory
pollutants may cause excessive sloughing of the fixed
film biomass. This problem may be rectified by
returning thickened secondary clarifier solids to the
fixed film process to help maintain a proper biomass
population.
Chemical Addition
The addition of chemicals or additives to
wastestreams in existing POTW treatment processes
can be used to improve pollutant removal. Nutrients
can be added to influent wastewaters, which have low
nutrient levels relative to their carbonaceous content,
to improve biological treatment. Lime or caustic can
be used to adjust wastewater pH for optimal biological
treatment or for coagulation and precipitation
treatment. Other chemical coagulants are used to aid
in removal of insoluble toxic pollutants and to improve
sludge settling. Powdered activated carbon may be
applied in activated sludge systems to remove toxic
organic compounds. A description of each of these
wastewater treatment additives is provided as follows.
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Table 7-1. POTW In-Plant Control Technologies for Categories of Toxic
Compounds
Biodegradable
Organic
Compounds and
Ammonia
Non-Biodegradable
Organic
Compounds
Volative Organic
Compounds
Heavy Metals and
Cationic Compounds
Biological Process Filtration
Control
Biological Process
Control
Filtration
Nutrient Addition
Activated Carbon Aeration
Coagulation/
Precipitation
Coagulation/
Precipitation
pH Adjustment
Nutrient Addition -
Addition of phosphorus, nitrogen or sulfur may in
some cases improve biological treatment of industrial
wastewaters with low nutrient concentrations.
Improved treatment is attributed to correcting a
nutrient deficient condition resulting from a high
industrial to domestic wastewater ratio. The optimal
BOD5/N/P ratio for municipal activated sludge
treatment is 100:5:1.
pH Adjustment —
Lime and caustic addition can be used to increase
influent wastewater pH prior to primary sedimentation
to enhance the precipitation of heavy metals. Some
metals, however, such as iron and chromium will go
into solution rather than precipitate at alkaline pH. The
optimum pH range for metals precipitation varies for
each type of metal and the solubility/precipitation
equilibrium can be affected by other factors such as
dissolved solids concentrations in the wastewater.
Lime and caustic can also be used to provide the
alkalinity necessary for efficient biological treatment.
Coagulant Addition —
Polymers and inorganic coagulants such as alum and
ferric chloride can be introduced to POTW
wastestreams to help remove insoluble pollutants.
Coagulants can be added to POTW influent
wastewater to increase the sedimentation of toxic
constituents in primary treatment and thereby
minimize the loading of toxic pollutants on the
biological treatment process. Coagulants can also be
added after the activated sludge aeration basins to
control sludge bulking or reduce effluent suspended
solids. The optimum conditions for coagulation can be
determined by conducting jar tests. These tests are
used to establish the optimum coagulant type and
dose, the proper mixing requirements, and the
flocculant settling rates for treatment (Adams et al.,
1981).
Coagulants can adversely affect the characteristics of
sewage sludges and could thereby alter ultimate
disposal methods. Coagulants may increase the
toxicity of the sludge (as measured by TCLP) as a
result of the removal of toxic wastewater constitutents
or as a result of the toxicity of the coagulant itself.
Thus, coagulants should be carefully evaluated prior
to use.
Activated Carbon --
The addition of powdered activated carbon (PAC) to
an activated sludge unit can increase the removal of
toxic organic chemicals. Organic pollutants that are
not biodegraded can be removed by adsorption onto
the surfaces of activated carbon particles. Activated
carbon also improves sludge settleability by providing
dense nuclei onto which sludge floes can
agglomerate. The PAC process has been used in
municipal wastewater treatment; however, recent
studies have shown (Deeny et.al., 1988) that PAC
regeneration by wet-air oxidation breaks down the
activated carbon particles to carbon fines, which carry
over the secondary clarifier weirs. In some cases
periodic additions of PAC to an aeration basin can be
used to minimize the effects of toxic slug loadings
and thereby improve the stability of the activated
sludge system.
Additional Treatment
Where process enhancement is not. feasible or will
not provide adequate toxics removal, physical addition
to or modification of the POTW can be undertaken.
Additional treatment processes could include
equalization prior to treatment, instrumentation
control, and advanced wastewater treatment
processes such as coagulation/flocculation, granular
media filtration, and granular activated carbon
treatment.
Equalization
Equalization can be used prior to biological treatment
units to dampen the effect of slug or diurnal loadings
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of high-strength industrial wastes. Equalization
facilities can be provided to either equalize
wastewater flows or wastewater concentrations. Flow
equalization is partially provided by existing primary
sedimentation tanks and can be enhanced by
increasing the size of the primary tankage.
Concentration equalization requires mixing of the
wastewater to moderate intermittent pollutant
loadings, and thus separate facilities must be
provided.
Instrumentation Control
Instrumentation/monitoring can be used to help
control slug loadings of toxic constituents in the
POTW influent wastewater. For example, transient
metals loadings may be controlled by continuously
monitoring the pH and conductivity of the influent
wastewater. A significant decrease in pH or an
increase in conductivity may indicate a slug loading of
toxic material (e.g., heavy metals). If this situation
occurs, the influent flow can be manually or
automatically diverted to a holding basin until the pH
and conductivity in the influent return to normal. At
that time, the diverted wastewater can be slowly
added to the influent wastestream in such a manner
that the pollutant concentrations are diluted prior to
treatment.
Advanced Wastewater Treatment
POTWs that only utilize primary and secondary
wastewater treatment may achieve toxicity or toxics
reduction by the addition of advanced wastewater
treatment process such as coagulation/flocculation,
sedimentation, granular media filtration, and granular
activated carbon. Each of these processes can
provide enhanced removal of constituents which may
be causing effluent toxicity.
Treatability Testing
Bench-scale and pilot-scale treatability tests are
commonly used to simulate treatment options
selected for wastewater testing. Bench-scale or
pilot-scale tests offer several advantages compared
with full-scale monitoring, including a more
manageable size and the ability to vary the operating
conditions to evaluate toxicity reduction. Treatability
methods can range from simple jar tests for testing
coagulation/flocculation options to flow-through
bioreactors for investigating biodegradation kinetics of
wastewater treatment.
During treatability testing, influent, effluent and
sidestream wastewaters of the treatment process are
tested for acute or chronic toxicity using methods
described by Mount and Anderson-Carnahan
(1988a) and Horning and Weber (1985),
respectively. Toxicity testing is used to assess the
effectiveness of the treatment process in reducing the
wastewater toxicity and to determine the fate of
toxicity in the treatment process. Definitive acute or
chronic toxicity tests (Peltier and Weber, 1985 and
Horning and Weber, 1985, respectively) should be
used at the completion of the treatability testing to
verify the option's capability to meet the NPDES
permit limit.
Activated Sludge
The basic parameters of interest in the design of
activated sludge systems include organic loading,
oxygen requirements, nutrient requirements; sludge
production, and sludge settleability and return rate.
Continuous flow systems are most useful for
evaluation of activated sludge systems; however, in
some cases batch systems may provide sufficient
treatability information (Adams et al., 1981).
Coagulation/Flocculation
The evaluation of coagulation and flocculation
treatment involves the use of bench-scale jar tests
or zeta potential tests to provide information on the
optimum coagulant type and dosage, mixing rates,
and flocculant settling rates for removal of solids and
flocculant suspensions (Adams et al., 1981). Results
of these tests are used to devise sedimentation
treatability tests for evaluating full-scale
coagulation/flocculation processes.
Sedimentation
Sedimentation involves removal of suspended solids
or flocculant suspensions by gravity settling.
Sedimentation is evaluated by conducting a series of
settling column tests which measure the settling rates
of solids or flocculant suspensions (Adams et al.,
1981). Test results are used to calculate a settling
profile which can be used for clarifier design.
Granular Media Filtration
Filtration testing involves scaled-down models
(usually pilot-scale) of full-sized filters. The choice
of filter media and test flow rates should correspond
to the intended design and operation criteria.
Although the process scale is reduced, the bed
gradation and thickness should be equivalent to full-
scale to predict actual treatment performance (Adams
et al., 1981).
Granular Activated Carbon
The carbon adsorption isotherm test is used to
determine the optimum type and dosage of activated
carbon for wastewater treatment (Adams et.al., 1981).
Results of this test are used to prepare bench-scale
or pilot-scale carbon columns which are used to
evaluate carbon exhaustion rates and the effect of
carbon regeneration on toxicity removal performance.
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Section 8
Toxicity Control Selection
Introduction
The goal of the TRE is to select and implement
toxicity control methods and technologies that will
achieve the TRE objective of meeting the permit
limits for effluent toxicity. The process of toxicity
control selection involves an assessment of the
potential control options and the selection of the best
option(s) for toxicity reduction based on technical and
cost considerations. In the first step of the selection
process, information from each stage of the TRE is
collected and reviewed to ensure that sufficient data
are available. These data should include information
on the magnitude and variability of the effluent toxicity
and toxicants over time. Following the information
review, the data are evaluated to identify feasible
toxicity control options. Finally, the feasible options
are compared to determine the preferred control
option(s).
The choice of in-plant toxicity control or
pretreatment toxicity control will depend largely on the
technical and economical feasibility of POTW
treatment modifications, and the quality of the
pretreatment data on IDs that contribute refractory
toxicity or toxicants to the POTW. Pretreatment
control will be feasible in situations where the TIE
data and the toxicity source evaluation data are
sufficient to definitively identify the sources of toxicity.
These data should provide an indication of the
variability of toxicity and toxics in the ID discharge. If
these conditions are satisfied, the municipality can set
local limits using the methods outlined in Section 6.
In-plant control will be preferred in cases where the
implementation of feasible treatment modifications or
additions is more cost-effective than pretreatment
control. In-plant options provide the POTW a direct
method of controlling effluent toxicity; however, in-
plant modifications or additions may result in
substantial increases in process operation
requirements and operating costs.
Evaluation of Control Options
The, TRE protocol is designed to identify possible
methods for toxicity reduction at the earliest possible
stage in the TRE. As shown in Figure 1-1, sufficient
information may be available for toxicity control
evaluation at several stages in the TRE: at the
completion of the PPE conventional pollutant
treatability tests, following the TIE, after Tier I
chemical-specific testing, at the end of the Tier I!
pretreatment evaluation, and at the completion of the
POTW in-plant control evaluation. The identified
control options must be based on ample data that
clearly demonstrates the technical feasibility of each
option. Toxicity control options that are appropriate for
each of these stages are described as follows.
PPE Treatability Tests
Treatability testing in the PPE may identify options for
conventional pollutant treatment which also reduce
effluent toxicity to acceptable levels. In addition the
optional TIE Phase I tests may provide information on
the presence of in-plant toxicants such as
suspended solids or chlorine which is corroborated in
the operations and performance review. The Phase I
information can be used to identify options for control
of the in-plant toxicants.
Potential control options may involve treatment
modifications or additions that are necessary to
improve conventional pollutant treatment and to
reduce or eliminate in-plant sources of identified
toxicants. Examples of these control options include
dechlorination treatment to eliminate toxic levels of
TRC and biological treatment optimization (e.g.,
increased MCRT) to improve conventional pollutant
removal which also reduces effluent toxicity.
TIE Tests
Results of Phase I testing may indicate the classes of
compounds causing effluent toxicity (e.g., non-polar
organic compounds) which may be amenable to
certain types of treatment (e.g., granular media
filtration). The feasibility of options for removal of
broad classes of toxicants can be evaluated in the
POTW in-plant control evaluation .(Section 7).
Feasible options developed from this evaluation are
described in a following subsection.
Alternatively, results of Phases II and III may identify
and confirm the specific toxic compounds in the
effluent. If the pretreatment program data are
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adequate to determine the sources of the toxicants,
local limits can be developed and evaluated as noted
in Section 6. In this case, pretreatment control would
be preferred over in-plant control because of the lower
costs of implementation. If sufficient pretreatment
program data on the toxicants is not available,
chemical-specific testing will be necessary to track the
sources of the toxicants.
Tier I Chemical-Specific Testing
Chemical-specific tracking in the Tier I evaluation may
locate the sources of the POTW effluent toxicants.
Once the sources have been identified, local limits
options can be developed and evaluated as discussed
in Section 6.
Tier II RTA Testing
Results of the Tier II testing are used to identify the
lUs contributing refractory toxicity to the POTW. A
ranking system indicates the major toxic contributors.
Based on these results, the POTW can require the IU
to limit the discharge of IU wastewater toxicity even
though the toxic constituents of the wastewater have
not been identified. In some cases, the municipality
may elect to perform optional TIE Phase I analyses in
the RTA to provide information on the toxic ID
wastewater constituents. This additional testing may
be conducted so that the municipality can set
numerical limits on a case by case basis.
POTW Treatability Testing
POTW treatability testing may indicate the in-plant
treatment options that can be applied to achieve
efficient toxicity reduction. These options may include
process enhancements such as biological process
control and nutrient addition, or additional treatment
processes such as equalization, coagula-
tion/flocculation, granular media filtration and
granular activated carbon. The treatability data should
include information on the variability of toxicity
treatment performance and the design criteria for
implementing the treatment option.
Selection of Toxicity Control Options
To aid in the final selection of toxicity control
alternatives, a list of pertinent selection criteria should
be prepared as shown in Table 8-1. Appropriate
selection criteria include the ability of each option to
reduce effluent toxicity to acceptable levels; the ability
to comply with other NPDES permit limits; capital,
operational, and maintenance costs; ease of
implementation; reliability; and the environmental
consequence of the remedy. Each alternative should
be rated in terms of these selection criteria and the
alternative with the least points based on
environmental, technical, and economic criteria should
be selected.
Table 8-1. Comparison of Selection Criteria for Toxicity
Control Operations*
Alternative
Selection Criteria
A B C D
Ability to achieve effluent toxicity limits
Ability to comply with other permits
Capital Cost
Operational Cost
Maintenance Cost
Ease of Implementation
Reliability
Environmental Impact
Rating criteria is 1 to 10, with 10 being the least favorable
situation.
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Section 9
Tox/c/ty Control Implementation
Once the evaluation and selection of toxicity control
options has been completed, the final steps in the
TRE are the implementation of the selected source
and in-plant control options, and follow up
monitoring to ensure permit compliance. The extent
of the implementation step will depend on the severity
of the effluent toxicity and on the complexity of the
selected control approaches. Depending on the
findings of the TRE, implementation may be as simple
as modification of POTW operating procedures or as
complex as expansion of the POTW's Pretreatment
Program or the design and construction of new
treatment facilities.
Implementation
Using the results of the previous steps in the TRE, a
Toxics Control Implementation Plan (TCIP) should be
developed. The TCIP should detail the results of the
TRE and should specify the control options for
reducing toxicity to allowable levels. For in-plant
control options, the TCIP should provide the basis of
design for the selected control options, provide capital
and operating costs, and define the time required for
design and construction. For source control options,
the selected pretreatment approach should be
detailed in the TCIP, and should specify the basis of
selection and technical justification of the local limits
and IU monitoring methods. In addition, the procedure
for implementing the revised pretreatment regulations
should be defined.
Follow Up Monitoring
Once a control technology has been implemented, a
follow up monitoring program should be prepared and
implemented to ensure the effectiveness of the
selected control options. In most cases, the
conditions and frequencies of this program will be set
by the regulatory agency. Additional monitoring
requirements set by the POTW for monitoring or
reporting by the IDs may also be required. This
program may include verification of statements from
industries that the required reduction of toxicity has
been made. Intensive effluent toxicity monitoring
should be performed on the POTW effluent to ensure
that toxicity has been reduced to acceptable levels
and that the TRE objectives have been met. Any
specific toxicants that were determined to be present
prior to implementation of control technology should
be monitored to ensure that there is no excursion
from the effluent limitations.
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Section 10
Quality Assurance/Quality Control
Introduction
A Quality Assurance/Quality Control (QA/QC) program
for the TRE should be developed and implemented to
insure the reliability of the collected data. The QA/QC
program should address the monitoring of = field
sampling and measurement activities, the review of
laboratory analysis procedures, and the
documentation and reporting of the analytical data. A
QA/QC program should be designed so that
corrective action can be quickly implemented to
detect and eliminate erroneous or questionable data
without undue expense to the project or major delays
in the schedule.
The POTW laboratory manager should ensure that
the specific QA/QC requirements for TRE activities
are addressed by the facility's QA/QC plan. If a
private consultant is to be used for all or part of the
TRE testing, the POTW laboratory manager should
request a QA/QC plan from the consultant and review
the consultant's proposed QA/QC activities. Whether
the TRE is to be performed by the POTW laboratory
or by a consultant, it is essential that the project
organization include competent chemists,
toxicologists and engineers who have adequate
knowledge of TRE methods.
The QA/QC document should be prepared prior to the
initiation of the TRE, and should contain the following
elements:
• QA/QC objectives;
® Sample collection and preservation techniques;
• Chain of custody procedures;
e Analytical QA/QC;
« Laboratory equipment maintenance;
• QA/QC training requirements;
9 Documentation and reporting procedures; and
• Corrective action protocols.
Sampling Collection and Preservation
To ensure quality control in sample collection
activities, the TRE Sampling Plan (Section 13) should
be strictly followed. In addition the QA/QC plan should
state the minimum sample volumes, maximum
sampling holding times and sample preservation
techniques for each analytical method. The sampling
requirements for conventional and priority pollutant
analyses are described in EPA's Methods for
Chemical Analysis of Water and Waste (USEPA,
1979) and Standard Methods for the Examination of
Water and Wastewater (APHA, 1985). Sampling
requirements for acute toxicity tests are provided by
Peltier and Weber (1985).
It is important to routinely assess the effects of
sampling holding times on wastewater toxicity to
predict how long samples can be kept before
changes in toxicity occur. The TIE Phase I manual
(Mount and Anderson-Carnahan, 1988a) describes
how testing the sample toxicity on the day of
collection and comparing this initial toxicity to its
baseline toxicity (tested one day later) can provide
information on appropriate sampling holding times for
toxicity analysis.
Other QA/QC considerations for TRE sample
collection include routine cleaning and inspection of
automatic sampling equipment, cleaning sample
containers according to the requirements for each
analytical method, and the collection of duplicate
samples and field blanks. Samples that are to be
used for toxicity and chemical analyses require
sample containers that are both toxicologically and
analytically clean. Toxicity tests are sensitive to even
slight sample contamination, thus equipment and
containers used for toxicity test samples require
special cleaning according to procedures outlined in
Peltier and Weber (1985).
Chain-of-Custody
A chain-of-custody (COG) form should accompany
all samples to document the collection, preservation,
and handling of samples. The COC form should
indicate the sample identification number, sample
type (i.e., composite or grab), date and time of
collection, a brief description of the sample, number
of samples taken, and name of the person taking the
sample. A field book should also be used to record
any field observations or conditions noted during
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sampling along with other pertinent information. Each
laboratory should identify a sample custodian to log in
and store samples collected during the TRE. This
sample custodian should acknowledge receipt of the
sample by signing the COG form and noting the date
and time of sample receipt, the sample identification
number, and the laboratory assession code. An
additional notation should be made each time aliquots
of the sample are tested for toxicity by noting the
analysis date and time, the analyst, and any changes
in the nature of the sample toxicity over time. All COG
forms should be maintained in a permanent file so
that information on specific samples can be easily
traced.
Analytical QA/QC
Analytical tests should provide data of an acceptable
quality for characterizing wastewater toxicity and for
evaluating methods and technologies for toxicity
reduction. Several of the test methods described in
this document are new and require careful attention
to unique QA/QC procedures. The special QA/QC
procedures for each TRE analytical test are
discussed below. Whenever possible, these
procedures should be followed to ensure precise and
accurate results.
Toxicity Identification Evaluation
Special precautions for TIE tests are discussed in the
Phase I, II and III manuals (Mount and Anderson-
Carnahan, 1988a, 1988b and Mount, 1988). In
general strict adherence to standard quality control
practices is not required in conducting Phase I
analyses due to the large number of toxicity tests to
be performed and the tentative nature of the toxicant
characterization. Nonetheless, system blanks and
controls should be used whenever possible to
indicate toxicity artifacts caused by the
characterization procedures. In Phase II more
attention should be paid to quality control in order to
identify interferences in toxicant characterization and
identification. Still greater attention to quality control
should be provided in Phase III. Sample manipulation
should be minimized in Phase III to prevent analytical
interferences and toxicity artifacts, and field
replicates, system blanks, controls and calibration
standards should be used extensively to allow a
precise and accurate determination of the sample
toxicants and toxicity.
Specific precautions for characterization (Phase I) and
toxicity testing in TIE analyses are provided below.
Aeration —
For sample air stripping or aeration tests, only a high
quality compressed air source should be used, oil,
water and dirt are undesirable contaminants in
compressed air; therefore, it is important to use
equipment which generates dry, oil free air. oil sealed
air compressors should not be used. Simple aeration
devices, such as those sold for use with aquariums
are acceptable provided that the ambient laboratory
air is uncontaminated (Mount and Anderson-
Carnahan, 1988a).
Filtration -
High purity water, which has been adjusted to a
specified pH, should be used to rinse filters between
filtration steps (Mount and Anderson-Carnahan,
1988a). Filtration equipment should be rinsed with
10% HNO3, acetone and high purity water between
sample aliquots. Filter toxicity can be checked by
testing filtered dilution water.
pH Adjustments -
Two concerns in the pH adjustment step involve
artificial toxicity caused by excessive ion
concentrations from the addition of acid and base and
silver contamination from some pH probes. The
baseline toxicity test acts as a control for indicating
whether addition of acid and base increase the
wastewater toxicity. Because toxic concentrations of
silver can leach from refillable calomel electrodes,
only solid state pH probes should be used.
Methanol/Cfs Column -
HPLC-grade methanol is required for SPE column
preparation and extraction steps. A blank toxicity test
should be conducted for each methanol reagent lot.
In addition a toxicity blank should be performed on
each SPE column to check for resin-related toxicity.
Oxidant Reduction -
Thiosulfate used in oxidant reduction tests may be
toxic at high concentrations. This potential
interference can be checked by adding increasing
quantities of thiosulfate to aliquots of the wastewater
sample, testing the resulting toxicity, and comparing
this toxicity to the sample's baseline toxicity.
EDTA Chelation -
Toxicity caused by the addition of EDTA can be
identified by observing increases in toxicity, relative to
the baseline toxicity, when increasing amounts of
EDTA are added to the wastewater sample.
Toxicity Tests —
The organisms used to test the sample toxicity prior
to and following each characterization step should not
be subject to undue stresses such as contamination
(Mount and Anderson-Carnahan, 1988a). The test
organisms should have had no prior exposure to
pollutants and their sensitivity should be constant
over time. To assess changes in the sensitivity of the
test organisms, a standard reference toxicant test
should be performed on a regular basis and
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accompanying quality control charts should be
developed (Peltier and Weber, 1985). These tests
should be performed monthly and should coincide
with the implementation of TIE tests. If test organism
cultures are not maintained in the laboratory, standard
reference toxicant tests should be performed with
each group of test organisms received. Information on
obtaining and culturing species for toxicity testing is
provided by Peltier and Weber (1985).
The quality of the dilution water used in toxicity tests
will depend on the purpose of the TIE test and
whether the test is being performed as an initial
characterization (Phases I and II) or for toxicant
confirmation (Phase III). Because much of Phase I
and parts of Phase II rely on relative toxicity
measurement, water which is of consistent quality
and will support growth and reproduction of the test
species is suitable for these phases of the TIE (Mount
and Anderson-Carnahan, 1988a). The objective of
Phase 111, however, is to confirm the true cause of
toxicity, thus artifacts are to be excluded and the
choice of dilution water should follow standard
toxicological practices (Peltier and Weber, 1985). In
general the physical/chemical characteristics of the
dilution water should reflect those of the receiving
water. Synthetic freshwater can be used for TIE tests;
however, laboratory deionized water should not be
used, because it may lack essential minerals such as
calcium and magnesium and may introduce toxic
levels of other cations.
Most species used in standard acute toxicity testing
do not require feeding during the test. The Phase I
manual (Mount and Anderson-Carnahan, 1988a),
however, recommends feeding the organisms in the
TIE test solutions at the beginning of TIE toxicity
tests. Feeding requirements for selected species are
described by Peltier and Weber (1985).
Dissolved oxygen measurements are generally not
made during TIE toxicity tests because the exposure
chambers have a surface to volume ratio that is large
enough for adequate oxygen diffusion. In cases where
low DO is a problem, DO adjustment should be
performed at a rate that will not unintentionally
change the sample toxicity.
Refractory Toxicity Assessment and Treatability
Tests
RTA and treatability tests are subject to a variety of
potential interferences due to the large number of
variables that must be accounted for and controlled
during testing. In performing toxicity tests for RTA and
treatability analyses, it is important to hold all
parameters potentially affecting toxicity constant so
that sample toxicity is the sole variable. Important
parameters to be controlled in RTA testing include the
test solution temperature, DO level and pH.
The QA/QC concerns for toxicity analysis in RTA and
treatability tests are the same as those expressed
above for TIE tests. Selection and use of test species
and. dilution water should follow procedures
addressed by Mount and Anderson-Carnahan
(1988a).
Potential sources of toxicity contamination should be
identified through the use of system blanks. As with
TIE testing, the filters used in RTA testing can be
tested to determine if toxicity is added during filtration.
Each of the solutions used in RTA testing including
synthetic wastewater and activated sludge should be
checked for toxicity. In the Patapsco TRE, the return
activated sludge used in the RTA batch tests was
found to be acutely toxic to Ceriodaphnia. Similarly,
the reagents used in treatability testing such as
chemical coagulants should be screened for toxicity.
To ensure precise and accurate results, field
replicates, calibration standards, and analytical
replicates should be routinely performed during RTA
and treatability testing. Results of these quality control
analyses can be used to calculate the precision,
accuracy and the sensitivity of each method.
Chemical Analyses
Quality control for chemical analyses includes the use
of calibration standards, replicate analyses, spiked
sample analyses, synthetic unknown analyses,. and
performance standards. The detection limits and the
recommended reagents for method calibration and
spiking are discussed in EPA's Methods for Chemical
Analysis of Water and Wastes (1979) and Standard
Methods for Examination of Water and Wastewater
(1985). General information on laboratory quality
control for chemical analyses is provided in EPA's
Handbook for Analytical Quality Control in Water and
Wastewater Laboratories (1972).
Equipment Maintenance
All facilities and equipment such as pH, DO and
conductivity meters, spectrophotometers, GC/MS and
HPLC instruments should be inspected and
maintained according to manufacturers'
specifications. A maintenance log book should be
used for each major laboratory instrument.
The measurement of toxicity or trace compounds in
wastewater samples requires the use of carefully
cleaned instruments and glassware. Instruments
which involve flow-through analysis such as
automated spectrophotometers should be inspected
to ensure that flow-through parts (i.e., tubing) are
periodically replaced. New glassware may be
contaminated with trace amounts of metals, therefore
any glassware being used in TIE toxicity tests for the
first time should be soaked for three days in 10%
nitric acid (Mount and Anderson-Carnahan, 1988a).
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For subsequent use in TIE tests, the glassware
should be washed with detergent, and sequentially
rinsed with 10% HNOa, acetone and finally high
purity water.
Documentation and Reporting of Data
Basic steps in a successful QA/QC program are the
documentation of the analytical data in meaningful,
exact terms, and reporting the analytical data in a
proper form for future interpretation and use. To
ensure the reliability of the data, its handling must be
periodically monitored and reviewed. This review
generally consists of three elements: an assessment
of laboratory record keeping procedures, a review of
the data calculations, and a review of the final
reported data, on the basis of these review steps and
the QA/QC analyses for precision and accuracy, the
data are accepted or rejected. This review process is
essential because some or all records may have to
be submitted for review by State or Federal pollution
control agencies.
Corrective Action
Procedures should be established to ensure that
QA/QC problems such as improper sampling
techniques, inadequate chain-of-custody records
and poor precision and accuracy results are promptly
investigated, and corrected. When a QA/QC
deficiency is noted, the cause of the condition should
be determined and corrective action should be taken
to preclude repetition.
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Section 11
Health and Safety
Overview
A health and safety (H&S).plan may be necessary in
performing TREs in order to establish policies and
procedures to protect workers from hazards posed by
TRE sampling and analytical activities. The general
guidelines outlined in this section should be integrated
into existing health and safety programs even if a
specific H&S plan is not required. Whether a specific
H&S plan is necessary or not will depend on the
specific conditions under which the TRE is being
conducted. For example, if the POTW operates under
a RCRA permit by rule, then health and safety must
be addressed when collecting and analyzing
hazardous wastes.
Important considerations for health and safety for
TRE studies include:
• Identification of personnel responsible for health
and safety matters;
• Health and safety training activities;
• Protective equipment required for TRE activities;
• Materials cleanup and disposal procedures; and
• Emergency response contingencies.
Detailed information on the preparation and scope of
health and safety plans is provided in the
Occupational Safety and Health Administration's
(OSHA's) Safety and Health Standards for General
Industry (1976). The following subsections discuss
specific health and safety considerations for selected
TRE activities.
Sample Collection and Handling
Working with wastestreams of unknown composition
is inherent to TREs. Samples of industrial sewer
discharges, municipal wastewater and sewage sludge
can contain a variety of toxic and hazardous materials
(e.g., pathogens, carcinogens, mutagens and
teratogens) at concentrations that can be harmful to
human health.
It is the responsibility of the laboratory sample
custodian to ensure that TRE samples are properly
stored, handled and discarded after use. Upon
sample storage, the sample custodian should indicate
the health and safety considerations for handling and
disposal of the sample. •
Exposure to toxic and hazardous sample constituents
should be minimized during sampling handling. The
principal routes of human exposure to toxics is via
inhalation, dermal absorption and/or accidental
ingestion. Exposure can be minimized through the
use of proper laboratory safety equipment such as
gloves, laboratory aprons or coats, safety glasses,
pipetting aids, respirators, and laboratory hoods.
Laboratory hoods are especially important when
testing wastewaters containing toxic volatile
substances such as volatile priority pollutant
compounds, hydrogen sulfide, or hydrogen cyanide.
Proper dermal protection such as using neoprene
gloves for solvent-containing wastes is also
important. Laboratory managers should consult the
manufacturers' specifications in selecting appropriate
clothing materials for protection against specific
chemicals.
Residual wastewater samples and wastes generated
during TRE studies should be disposed of properly.
Residual municipal wastewater and other non-
hazardous wastes can be disposed directly into the
sink drain if the TRE is being conducted at the
POTW. Residual industrial samples and other wastes
that potentially contain hazardous materials should be
decontaminated and/or disposed of in accordance
with hazardous waste regulations (NIOSH, 1977).
Analytical Methods
Specific precautions that should be followed for
selected TRE analytical techniques are described
below.
Toxicity Identification Procedures (TIE)
EPA's Phase I manual (Mount and Anderson-
Carnahan, 1988a) addresses the general health and
safety concerns involved in performing the Phase I-
III analyses. Ventilation is a specific concern when
performing the Phase I air-stripping tests. These
tests should be performed in laboratory hoods to
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prevent the inhalation of toxic volatile compounds
resulting from air-stripping.
Health and safety considerations for aquatic toxicity
testing are addressed by Peltier and Weber (1985).
Special precautions need to be taken for on-site
mobile laboratories in the handling and transportation
of chemicals, supply of adequate ventilation and safe
electrical power, and disposal of waste materials.
Refractory Toxicity Assessment and Treatability
Tests
Proper ventilation is also important when conducting
refractory toxicity assessments and treatability tests in
the laboratory. Hoods should be used to capture and
vent potential volatile compounds that are stripped
from the wastewater during biological treatment tests.
Physico-chemical treatability testing may involve the
use of hazardous reagents such as acids or caustics.
Caution should be taken in the handling and disposal
of these chemicals.
Chemical Analyses
A number of reagents used for chemical-specific
analyses (e.g., priority pollutants, COD, etc.) are toxic
or hazardous substances. Analysts should be familiar
with safe handling procedures for all reagents used in
testing, including the practice of proper chemical
storage to avoid storing incompatible chemicals
together (Miller, 1985). After use, the waste
chemicals should be converted into a less hazardous
form in the laboratory before disposal (NRC, 1983) or
disposed of by a commercial disposal specialist.
General Precautions
Additional laboratory safety procedures (USEPA, 1977
and ACS, 1979) that should be followed in TRE
studies include: 1) the use of safety and protective
equipment such as eye protection (safety goggles,
eye wash), fire hazard protection (smoke and fire
detectors, fire extinguishers), and electrical shock
protection (ground-fault interrupters for wet
laboratories); 2) protocols for emergency response
and materials cleanup; and 3) personnel training in
health and safety procedures.
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Section 12
Facilities and Equipment
Introduction
Laboratories used for a TRE study should be
equipped with all the basic and specialized laboratory
equipment required to conduct the TRE, and
laboratory personnel should be skilled and
experienced in operating this equipment. The facilities
and equipment needed to perform a TRE will be
different for each POTW and will depend on the
site-specific factors involved in the TRE. In general,
the minimum facilities and equipment for initiating a
TRE will include the equipment used in the TIE Phase
I characterization tests. As additional information
becomes necessary, the facility and equipment needs
will be more site-specific and will depend both on
the physical/ chemical characteristics of the causative
toxicants and on the toxicity control approaches to be
evaluated. For example, the selection of bench-
scale equipment and/or pilot plant facilities for
treatability studies will be dictated by the control
options to be tested (i.e., physical/chemical
processes such as filtration or biological processes
such as increased SRT control).
The choice of whether to work on-site or off-site
will depend on the stage of the TRE, the methods
used for tracing toxicity to its sources, and the
requirements for treatability testing. In general, the
equipment and time required for conducting TIE tests
makes on-site testing less feasible. If the loss of
sample toxicity over time is minimal, TIE samples can
be shipped and tested off-site, usually at less cost
than on-site testing. If toxicity tracking using RTA
tests is required, on-site testing is mandatory,
because fresh samples of the POTW acclimated
biomass must be used. In addition, treatability tests
which require continuous supplies of POTW influent
or process wastewaters and/or activated sludge (i.e.,
flow-through bioreactor tests) can be more efficiently
conducted in on-site facilities. Some treatability
evaluations require unique or sophisticated equipment
(e.g., ultra-filtration apparatus) that is not readily
available for on-site work. In these situations, the
equipment vendor may be able to conduct the
required tests at the manufacturing facility.
The general equipment requirements for each of the
main TRE methods are summarized below.
Toxicity Identification Evaluations
Laboratories should be stocked with all of the
equipment necessary to conduct Phase I
characterization tests including filtration and air
stripping equipment, pH meter, Cta solid phase
extraction columns, fluid metering pumps, and the
required reagents. Because of the large number of
toxicity tests to be performed for Phase I testing, it
may be more cost-effective to culture the test
species than purchase them. Equipment needs for
culturing standard test species are described by
Peltier and Weber (1985).
More sophisticated analytical equipment is required
for the Phase II causative toxicant identification and
Phase III causative toxicant confirmation procedures.
The choice of analytical instruments for these
procedures will depend on the compound to be
measured. Equipment that may be required includes:
gas chromatograph-mass spectrometer (GS/MS),
high pressure liquid chromatograph (HPLC), atomic
absorption spectrometer (AA), inductively coupled
plasma spectrometer (ICP), UV-VIS
spectrophotometer, ion chromatograph, ion specific
electrodes, pH meter, conductivity meter and
salinometer. Use of inert materials such as
perfluorocarbon plastics for Phase II and III are
recommended to protect against toxicity artifacts
(Mount and Anderson-Carnahan, 1988a).
Refractory Toxicity Assessment and Treatability
Tests
Laboratories should be equipped with the basic
equipment for setting up and operating the RTA batch
reactors including an air supply, air diffusers, and a
laboratory hood. Instruments for measuring inhibition
include respirometer and/or oxygen meters, total
organic carbon (TOG) analyzer, spectrophotometers
for COD and nutrient analyses, drying oven, muffle
furnace, and analytical balance. The equipment for
toxicity testing will depend on the choice of toxicity
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screening tests. Depending on the species to be
used, it may be more economical to culture the test
organisms than purchase them. In some cases it may
be necessary to use a rapid screening test such as
a bacterial bioluminescence test (e.g., Microtox TM).
General Analytical Laboratory Equipment
General laboratory equipment such as refrigerators, a
water purification system and commonly-used
reagents are needed to support the TIE and RTA
analyses.
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Section 13
Sample Collection and Handling
Introduction
The most important criterion in sampling is to obtain a
sample that is representative of the discharge. To
ensure that a sample represents the typical
toxicological and chemical quality of the wastewater,
several samples will need to be collected. Guidelines
for determining the number and frequency of samples
required for characterization are presented in EPA's
Handbook for Sampling and Sample Preservation of
Water and Wastewater (Berg, 1982). This handbook
should only be used as a guide, however, because it
does not specifically address the requirements for
TRE sampling.
A sampling plan should be prepared to document the
procedures to be followed in TRE sampling. This plan
should contain the following elements:
• Description of sampling locations;
• Sampling equipment and methodology; and
• Sample delivery requirements.
These elements are discussed in the following
subsections. QA/QC procedures for sampling, which
include identifying the minimum volume requirements,
holding times and preservation techniques for
samples, preparing chain-of-custody forms, and
maintaining sampling equipment, are addressed in
Section 10.
Sampling Location
Sampling locations should be established where the
wastestream is readily accessible and well-mixed.
When sampling wastestreams within the POTW, care
should be taken in excluding unwanted wastestreams
and in selecting a sampling point that is most
representative of the discharge (e.g., the common
discharge channel for secondary clarifiers). The
sampling location for the POTW effluent should
correspond with the sampling point stated in the
NPDES permit for biomonitoring. If the permit does
not specify whether the effluent sample is to be
collected prior to or following the
chlorination/dechlorination treatment process, the
choice of a sampling location will depend on the
toxicants of concern. Sampling before and after
chlorination/dechlorination may be needed to
differentiate between toxicity caused by pass-
through and toxicity resulting from chlorination (i.e.,
TRC).
Wastewater sampling for toxicity source evaluations
requires knowledge of sewer discharge locations. In
some cases ILJs may have multiple sewer discharges
which need to be accounted for. Sampling may be
conducted at the point of sewer discharge or in areas
within the municipal sewer collection system. The
choice of sampling locations for sewer line tracking
will be based on existing pretreatment program data
indicating the probable toxic sewer lines within the
collection system. If these data are not available, a
sampling scheme can be devised to locate toxic
sources through the process of elimination of
segments of the collection system.
RTA testing requires samples of the POTW influent
(primary effluent) and activated sludge. Primary
effluent samples should be collected at the overflow
weirs of the primary sedimentation tanks. Activated
sludge samples can be collected from the aeration
basin effluent weirs or the return activated sludge
pipelines.
POTW Sampling
The choice of grab or composite samples of POTW
wastestreams (i.e., effluent and influent wastewater
and process wastestreams) will depend on the
physical/chemical characteristics and variability of the
toxicants. Initial effluent toxicity characterization
(Phase I) should utilize 24-hour composite samples
in order to ascertain the variability of the causative
agents over time. If acute effluent toxicity is not easily
observed in 24-hour time composites, flow
proportional composite or grab samples may be used
to observe possible flow-related peaks of toxicity. In
the latter phases of the TIE, grab samples are
recommended to determine the variability in the type
and concentration of effluent toxicants (Mount and
Anderson-Carnahan, 1988a). A discussion of the
use of grab versus composite sampling for toxicity
tests is provided by Peltier and Weber (1985). The
choice of a sampling technique for chemical-specific
analyses is dependent on the type of compounds to
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be measured (e.g., grab sampling for volatile organic
compounds).
When evaluating the treatment efficiency of the
POTW or its unit processes, collection of the influent
and effluent wastewaters should be lagged by the
hydraulic detention time of the treatment process in
order to get comparable samples. In addition,
samples should be collected during representative
discharge periods. An evaluation of the condition of
the facility's treatment system at the time of sampling
can be made by comparing the effluent sample
concentrations of BOD, TSS, and other pollutants to
long-term historical averages and/or permitted
values for those parameters. Such a comparison will
provide an indication of the operational status of the
treatment system on the day of sampling.
The sample volume requirements for Phase I tests
are provided in the Phase I manual (Mount and
Anderson-Carnahan, 1988a). Volume requirements
for POTW samples used in RTA tests are given in
Sections 5 and 6.
If TIE or physical/chemical treatability testing is being
conducted off-site, samples should be shipped on
ice to the testing facility. RTA and some biological
treatability tests require fresh or continuous samples
of POTW wastestreams, which requires testing to be
conducted on-site. Samples of activated sludge
should be delivered to the on-site laboratory and
used immediately in testing to prevent changes in the
biomass that can occur during long term storage.
Biomass samples should be vigorously aerated for a
minimum of 15 minutes before use in the RTA or
treatability tests. POTW influent and process
wastewater samples required for on-site RTA or
treatability studies should be used on the day of
sample collection.
Sewer Discharge Sampling
As with POTW sampling, the choice of grab or
composite samples of indirect discharges will depend
on the physical/chemical characteristics and variability
of the toxicants. The sample type will also be dictated
by the stage of the toxicity source evaluation. In Tier I
testing 24-hour flow proportional composite samples
are recommended to characterize daily variability
while accounting for variations in flow. Flow
proportional sampling should be scheduled to
coincide with production schedules for industrial
discharges, the frequency of intermittent inputs for
RCRA discharges, and the schedule of remedial
activities for CERCLA discharges. This information is
usually available in the POTW's pretreatment program
reports.
Sampling techniques for flow proportional composites
should account for the potential loss of volatile
compounds. For samples collected for chemical
analysis or refractory toxicity testing, zero headspace
sampling methods can be used to minimize volatile
losses. In some cases grab sampling may be used in
lieu of zero headspace methods to reduce sampling
costs; however, care should be exercised in
collecting samples that are representative of the
discharge.
In the Tier II evaluation grab sampling can be used in
addition to composite sampling to assess the
variability of the toxicants. This type of sampling
requires in-depth knowledge of the production
schedules and the pretreatment operations of the
discharger.
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Section 14
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Water Pollution Control Federation Conference,
Philadelphia, Pennsylvania.
Durkin, P.F., C.R. Ott, D.S. Pottle and G.M. Szal.
1987. The Use of the Beckman MicrotoxTM
Bioassay System to Trace Toxic Pollutants Back
to Their Source in Municipal Sewerage Systems,
In: Proceedings of the Water Pollution Control
Federation Association Annual Meeting, New
Hampshire.
Fava, J.A., D. Lindsay, W.H. Clement, R. Clark, S.R.
Hansen, S. Moore,and P. Lankford. 1988.
Generalized Methodology for Conducting
Industrial Toxicity Reduction Evaluations. Water
Engineering Research Laboratory, Cincinnati,
Ohio.
Grady, C.P.L. 1985. Biodegradation: Its Measurement
and Microbiological Basis. Biotechnology and
Bioengineering, Vol. 27 pp. 660-674.
Horning, W. and C.I. Weber. (Eds.) 1985. Short-
Term Methods for Estimating the Chronic Toxicity
of Effluents and Receiving Waters to Freshwater
Organisms. Environmental Monitoring and
Support Laboratory, Cincinnati, Ohio. EPA
600/4-85-014.
Jirka, A.M. and M.J. Carter. 1975. HACH COD
Procedure for the Bausch & Lomb Spec 20, Anal.
Chem. Vol. 47 No. 8.
Kang, S.J. et al. 1983. ATP as a Measure of Active
Biomass Concentration and Inhibition in Biological
Wastewater Treatment Processes. In:
Proceedings of Purdue Industrial Waste
Conference, Ann Arbor, Michigan.
14-1
-------
Kirsh, E.J., C.P.L. Grady and R.F. Wukasch. 1985.
Protocol Development for the Prediction of the
Fate of Organic Priority Pollutants in Biological
Wastewater Treatment Systems, Environmental
Protection Agency, Cincinnati, Ohio.
Lankford, P.W., W.W. Eckenfelder Jr., and K.D.
Torrens. 1987. Technological Approaches to
Toxicity Reduction in Municipal and Industrial
Wastewaters. Virginia Water Pollution Control
Association Meeting, Norfolk, Virginia.
Metcalf and Eddy, Inc. 1979. Wastewater Engineering
Treatment/Disposal/ Reuse. McGraw Hill.
Miller, R.J. 1985. Tips for the Safe Storage of
Laboratory Chemicals Overflow, Volume II.
Mount, D.I. 1988. Methods for Aquatic Toxicity
Identification Evaluations: Phase III. Toxicity
Identification Procedures. National Effluent
Toxicity Assessment Center. Quluth, Minnesota.
EPA 600/3-88-036.
National Institute of Occupational Safety and Health.
1977. Working With Carcinogens. Public Health
Service, Centers for Disease Control. Publication
No. 77-206.
National Research Council. 1983. Prudent Practices
. for the Disposal of Chemicals from Laboratories.
Neiheisel, T.W., W.B. Horning, B.M. Austern, D.F.
Bishop, T.L. Reed, and J.F. Estenik. 1988.
Toxicity Reduction at Municipal Wastewater
Treatment Plants. Journal Water Pollution Control
Federation. Vol. 60 No. 1 pp. 57-67.
Occupational Safety and Health Administration. 1976.
OSHA Safety and Health Standards, General
Industry. 29 CFR 1910. OSHA 2206 (Revised).
Peltier, W. and C.I. Weber. (Eds.) 1985. Methods for
Measuring the Acute Toxicity of Effluents to
Freshwater and Marine Organisms. 3rd Edition.
Environmental Monitoring and Support Laboratory,
Cincinnati, Ohio. EPA 600/4-85-013.
Philbrook, D.M. and C.P.L. Grady. 1985. Evaluation of
Biodegradation Kinetics for Priority Pollutants. In:
Proceedings of the Purdue Industrial Waste
Conference. Ann Arbor, Michigan.
Slattery, G.H. 1984. Effects of Toxic Influent on
Patapsco Wastewater Treatment Plant
Operations. Water Pollution Control Federation
Conference, New Orleans, Louisiana.
Sullivan, E.G., D.F. Bishop, J.A. Botts, J.W. Braswell,
G.H. Slattery and W.L Goodfellow. 1987. Effluent
Toxicity Monitoring Methodology Evaluated for
Five Industrial Dischargers. Proceedings of the
Purdue Industrial Waste Conference, Ann Arbor,
Michigan.
Techline Instruments, Inc, 1984. Techline Laboratory
Respirometer Operating Manual, Fond du Lac,
Wisconsin.
U.S. Environmental Protection Agency. 1972.
Handbook for Analytical Quality Control in Water
and Wastewater Laboratories. USEPA. Analytical
Quality Control Laboratory, Cincinnati Ohio.
U.S. Environmental Protection Agency. 1977.
Occupational Health and Safety Manual. Office of
Planning and Management, Washington, D.C.
U.S. Environmental Protection Agency. 1979a.
Methods for Chemical Analysis of Water and
Waste. Cincinnati, Ohio. EPA 600/4-79-020.
U.S. Environmental Protection Agency. 1979b.
Methods 624 and 625: GC/MS Methods for
Priority Pollutants. Federal Register
44(223):69532-69558.
U.S. Environmental Protection Agency. 1980.
Inductively Coupled Plasma/ Atomic Emissions
Spectrometric Methods for Trace Elements
Analysis of Water and Wastes.
U.S. Environmental Protection Agency. 1983a..
Guidance Manual for Pretreatment Program
Development. Office of Water Enforcement and
Permits, Washington, D.C.
U.S. Environmental Protection Agency. 1983b.
Treatability Manual. Office of Research and
Development. Washington, D.C. EPA 600/2-
82-001a.
U.S. Environmental Protection Agency. 1984.
Handbook on Improving POTW Performance
Using the Composite Correction Program
Approach.Center for Environmental Research
Information, Cincinnati, Ohio. EPA 625/6-84-
008
U.S. Environmental Protection Agency. 1985a.
Technical Support Document for Water Quality
Based Toxics Control. Office of Water
Enforcement and Permits, Washington, D.C.
U.S. Environmental Protection Agency. 1985b. Master
Analytical Scheme for Organic Compounds in
Water. Office of Research and Development.
Cincinnati, Ohio. EPA 600/4-85-008.
U.S. Environmental Protection Agency. 1987a.
Guidance Manual on the Development and
Implementation of Local Discharge Limitations
Under the Pretreatment Program. Office of Water
Enforcement and Permits. Washington, D.C.
U.S. Environmental Protection Agency. 1987b. Permit
Writer's Guide to Water Quality-Based
Permitting for Toxic Pollutants. Office of Water
Enforcement and Permits, Washington, D.C.
14-2
-------
U.S. Environmental Protection Agency. 1988a. Draft
Guidance Document for Writing Case by Case
Permit Requirements for Municipal Sewage
Sludge. Office of Water Enforcement and permits,
Washington, D.C.
U.S. Environmental Protection Agency. 1988b.
Development of Sludge Loading Control
Programs for Publicly Owned Treatment Works.
Office of Water Enforcement and Permits,
Washington, D.C.
Water Pollution Control Federation. 1976. Operation
of Wastewater Treatment Plants. A Manual of
Practice. Water Pollution Control Federation,
Washington, D.C.
Weber, C.I., W.B. Horning, D.J. Klemm, W.T.
Neiheisel, P.A. Lewis, E.L. Robinson, J.
Menkedick, and F. Kessler. 1988. Short-term
Methods for Estimating the Chronic Toxicity of
Effluents and Receiving Waters to Marine and
Estuarine Organisms. U.S. Environmental
Protection Agency, EPA/600/4-87-028.
Cincinnati, Ohio.
14-3
-------
-------
Sect/on f5
Bibliography
Abel, M., W. Giger, and M. Koch, 1985. Behavior of
Nonionic Surfactants in Biological Wastewater
Treatment. In: Organic Micropollutants in the
Aquatic Environment. Proceedings of the 4th
European Symposium, Vienna, Austria, October,
1985.
Abel, M. and W. Giger. 1985. Determination of
Alkylphenols and Alkylphenol Mono and
Diethoxylate in Environmental Samples by High-
Performance Liquid Chromatography. Analytical
Chemistry Journal (57).
Abel, M. and W. Giger. 1985. Determination of
Nonionic Surfactants of the Alkylphenol
Polyethoxylate Type by High-Performance Liquid
Chromatography. Analytical Chemistry Journal,
57(13).
Ayres, G.H. 1970. Quantitative Chemical Analysis.
Harper and Row, Inc., New York.
De Renzo, DJ. 1981. Pollution Control Technology
for Industrial Wastewater. Noyes Data
Corporation, New Jersey.
Eckenfelder, W.W. 1980. Principles of Water Quality
Management, CBI Publishing Company.
Federal Register. 1984. U.S. EPA. Development of
Water Quality Based Permit Limitations for Toxic
Pollutants; National Policy. Vol. 49 No. 48 March
9, 1984.
Giger, W., E. Stephanov, and C. Schaffner. 1981.
Persistent Organic Chemicals in Sewage
Effluents: Identification of Nonxylphenols and
Nonxylphenolethoxylates by Gas Capillary Gas
Chromatography. Journal of Chemosphere,
10(11).
Giger, W., H. Brunner, and C. Schaffner. 1984. 4-
Nonxylphenol in Sewage Sludge: Accumulation of
Toxic Metabolites from Nonionic Surfactants.
Science Journal, 225.
Goodfellow, W.L. and W.L. McCulloch. 1987. A
Technique for the Rapid Evaluation of Effluent
Acute Toxicity. In: Proceedings of the 8th Annual
SET AC Meeting, Pensacola, Florida.
Maromini, A. and W. Giger. 1987. Simultaneous
Determination of Linear Alkylbenzenesulfonates,
Alkylphenol Polyethoxylates and Nonxylphenol by
High-Performance Liquid Chromatography.
Analytical Chemistry Journal (59).
McEvoy, J. and W. Giger. 1986. Determination of
Linear Alkylbenzenesulfonates in Sewage Sludge
by High Resolution Gas Chromatography/Mass
Spectrometry. Environmental Science and
Technology Journal, 20(4).
Patterson, J.W. 1985. Industrial Wastewater
Treatment Technology 2nd Edition. Butterworths.
Peters, R.W. and Y. Ku, 1984. Removal of Heavy
Metals from Industrial Plating Wastewaters by
Sulfide Precipitation. Proceedings of the Industrial
Wastes Symposium, (57th Annual Conference).
Water Pollution Control Federation. 1982. Wastewater
Treatment Plant Design, Manual of Practice No.
8.
Water Pollution Control Federation. 1983. Nutrient
Control. Manual of Practice FD-7, Facilities
Design.
15-1
-------
-------
Appendix A
Case Histories
A. Baltimore, Maryland
In January 1986 the EPA, in cooperation with the City
of Baltimore, began a research study to develop a
pragmatic approach and methods for conducting
TREs at municipal wastewater treatment plants (Botts
et al., 1987). The City's Patapsco Wastewater
Treatment Plant (WWTP) was selected for this study
because of substantive influent toxicity and history of
intermittent pass-through of toxicity to receiving
waters. In addition, EPA was interested in conducting
a TRE at an urban wastewater treatment plant, like
the Patapsco WWTP, which receives its influent from
a wide range of industrial discharges. The objectives
of the TRE were to characterize the WWTP's
capability for treatment of conventional pollutants and
toxicity, evaluate techniques to identify the specific
components of the toxicity, and assess methods to
trace toxicity to its source(s).
The study results demonstrated that the WWTP
influent had significant acute and chronic toxicity and
substantial amounts of this toxicity remained following
secondary treatment even though the WWTP
achieved consistent conventional pollutant removal.
An evaluation of the WWTP operations indicated that
the treatment performance was not the major cause
of the effluent toxicity. Ceriodaphnia dubia was a
more sensitive indicator of acute effluent toxicity than
Mysidopsis bahia or MicrotoxTM.
A toxicity identification evaluation identified non-polar
organic compound(s) as the main cause(s) of effluent
toxicity; however, GC/MS analysis of the non-polar
organic fractions of the wastewater did not lead to
definitive determination of the specific non-polar
compounds. The TIE results did show, however, that
the non-polar organic compounds have high octanol
to water partition coefficients. The compounds sorbed
onto solids in the plant effluent. Further testing found
that solids (> 0.2 pm) were the major toxic fraction.
An evaluation of toxic industrial wastewater samples
from selected candidate industries was performed to
determine the major contributors of refractory toxicity
to the WWTP. The results of this evaluation were
used to rank contributors with respect to their
refractory toxicity loading.
B. Akron, Ohio
A survey of six Ohio municipal wastewater treatment
plants was conducted to determine the level of
wastewater toxicity reduction that occurs in municipal
treatment plants (Neiheisel et.al., 1988). Of the six
WWTPs, the City of Akron wastewater treatment plant
(Botzum WWTP) received the most toxic influent
wastewater. Although the Botzum WWTP achieved
significant toxicity reduction, the effluent discharge
comprised a large proportion of the Cuyahoga River
flow. A biological impact assessment study of the
Cuyahoga River in 1984 revealed a severe impact on
aquatic communities downstream of the plant
discharge. A preliminary review of the plant's
operating records also revealed intermittent bypassing
of raw wastewater during storm events.
On the basis of the preliminary survey results, the
Botzum WWTP was selected as a site for a toxicity
reduction evaluation. The TRE involved conducting
toxicity tests of the plant discharge, including the
bypass streams, to characterize the variability and
source(s) of toxicity that may have an effect on the
river water quality. In addition, an attempt was made
to identify the compounds causing the toxicity through
physico-chemical fractionation and toxicological
examination (TIE) of the effluent.
The TIE testing revealed that the toxicity was largely
in the eighty-five percent methanol eluate of the
SPE column, which indicates that the toxicant(s) is a
non-polar organic compound(s). Metals were also
identified as possible effluent toxicants. Results of
acute toxicity tests of the effluent and the CSO
indicated that although bypassed wastewater may
contribute intermittently to the poor river quality, the
continuous discharge of toxic materials in the effluent
was probably the major cause of the observed
impact.
Continued toxicity monitoring indicated that the acute
effluent toxicity ended abruptly in the summer of
1986. The cause of this abatement is not known, but
may have been related to one or more of the
following events: an increase in the concentration of
activated sludge solids in the plant bioreactors;
cessation of discharge by a large chemical
A-1
-------
manufacturing plant; reduction in the frequency of
wastewater bypassing; or the cumulative effects of
plant process and pretreatment program
improvements. Biosurveys of the Cuyahoga River in
1986, however, continued to show poor water quality
despite the decrease in effluent toxicity. It is possible
that either not all of the toxic wastewater sources
were identified, or the recovery rate of the river is
slower than anticipated.
C. Billerica, Massachusetts
A toxicity source evaluation study was conducted at
the Billerica WWTP to evaluate the usefulness of the
Microtox toxicity test in tracing the source(s) of
toxicity in the WWTP's collection system (Durkin
et.al., 1987). Billerica WWTP was selected for this
study because its influent was found to be toxic as
measured by MicrotoxTM.
The Billerica study was conducted in five stages: first,
an initial screening of the WWTP influent was
conducted; next, toxicity tests were performed on
samples from pumping stations in the sewer
collection area; the time of day when toxicity was
found in the most toxic pump station sewers was
determined; toxicity screening was performed on the
main sewer lines above the toxic pump stations; and
finally, testing of the tributaries to the main sewer
lines was initiated.
Of the eleven pump station sewers tested, two were
found to have very toxic wastewaters. In one of the
two toxic pump station sewers, high toxicity levels
occurred only during a daily 8:00 am to 2:00 pm time
period. Further investigation of this pump station
sewer isolated the principal source(s) of toxicity to
an industrial park.
This study was successful in screening for possible
sewer collection areas contributing toxicity to the
WWTP. This screening method appears to be a
useful initial technique for tracing WWTP influent
toxicity. However, a final determination of the sources
of toxicity that are refractory to treatment provided by
the municipal WWTP would require treating the sewer
samples in a simulation of the WWTP prior to toxicity
analysis.
References
Bolts, J.A., J.W. Braswell, E.G. Sullivan, W.C.
Goodfellow, B.D. Sklar and A.G. McDearmon.
1987. Toxicity Reduction Evaluation at the
Patapsco Wastewater Treatment Plant. Water
Engineering Research Laboratory, Cincinnati,
Ohio.
Durkin, P.P., C.R. Ott, D.S. Pottle and G.M. Szal.
1987. The Use of the Beckman MicrotoxTM
Bioassay System to Trace Toxic Pollutants Back
to Their Source in Municipal Sewerage Systems.
In: Proceedings of the Water Pollution Control
Federation Association Annual Meeting, New
Hampshire.
Microbics Corp. 1982. MicrotoxTM System Operating
Manual, Carlsbad, California.
Neiheisel, T.W., W.B. Horning, B.M. Austern, D.F.
Bishop, T.L. Reed, and J.F. Estenik. 1988.
Toxicity Reduction at Municipal Wastewater
Treatment Plants. Journal Water Pollution Control
Federation. Vol. 60 No. 1 pp. 57-67.
A-2
-------
Appendix B
Pretreatment Program Review
Introduction
The objective of the pretreatment program review
(PPR) is to gather manufacturing, pretreatment, and
discharge data on the industrial dischargers to the
municipal treatment plant (Table 2-2). These data
together with the results of POTW effluent toxicity
tests can be used to identify possible sources of
toxicity and provide insight as to probable control
technology options. The pretreatment program
information should include flow and chemical
monitoring data on the IDs, descriptions and
schedules of industrial production campaigns, and
inventories of chemicals used in production. The final
outcome of this, review should :be an improved
understanding of the industries' processes and
chemical usage, and the possible identification of
sources of toxicity.. Source identification through the
pretreatment program review has been successful in
reducing effluent toxicity at POTWs with a limited
number and type of industrial inputs (Diehl and Moore,
1987). , . '
General Procedure
The main steps in a PPR are to: 1) gather the
pertinent data; 2) compare the data to POTW effluent
toxicity results and/or TIE data; 3) identify potential
influent source(s) of toxicity; and 4) evaluate and
recommend a toxicity control option(s). A brief
description of each of these steps is as follows.
Collect Data on Individual Dischargers to PQTW
Data on all categorical, significant non-categorical and
other potential toxic dischargers (e.g., Ills with local
limits, and RCRA and CERCLA inputs) should be
collected. A list of pertinent information that should be
considered in a PPR is presented in Table 2-2. The
data collection effort should include a survey of each
IU, using the example checklist shown in Table B-1.
Information on chemicals that may be used in
manufacturing processes can be obtained from the
Encyclopedia of Chemical Technology (Kirk-Othmer).
Although OSHA regulations require that information on
hazardous chemicals is to be made available to the
public on Material Safety Data Sheets (MSDS),
information on various "specialty" chemicals
can be difficult to obtain. When data on a "specialty"
chemical are not disclosed, a literature review can be
performed to determine the chemical's acute toxicity
and biodegradability. This information allows
assumptions to be made concerning the
biodegradability of the chemical at the POTW and the
potential for the chemical to cause effluent toxicity. An
initial indication of the possible toxics causing effluent
toxicity can be made by comparing expected effluent
toxics concentrations to water quality criteria or
toxicity values provided in the literature.
Compare PPR Data to POTW Effluent Toxicity
Results
Information on the magnitude, variability, and nature of
the POTW effluent toxicity can be compared with the
PPR data to determine the sources(s) of possible
problem chemicals. This comparison can be made
using statistical analyses to determine if the variability
in the source characteristics can be related to the
variability in the POTW effluent toxicity. A description
of data analysis techniques for identification of
potential sources of toxicity follows.
Data Analysis Techniques for Comparing POTW
and Industry Pretreatment Data
Two types of statistical analyses can be used to
compare the pretreatment program and POTW
effluent toxicity data: linear regression (Draper and
Smith, 1966) and cluster analysis (Pielou, 1984 and
Romesburg, 1984). Linear regression analysis is used
to find correlations among the variables in the
database and to relate changes in POTW effluent
toxicity to the variables. A cluster analysis using
pattern recognition software can weigh and evaluate
the significance of toxics/toxicity correlations. The
determination of concentration/response relationships
through statistical analysis should not be considered
as a definitive answer to toxicity tracking because of
the complexity of the factors contributing to toxicity in
POTW effluents.
The following example illustrates how a stepwise
linear regression technique can be used in PPR
assessment. The technique is used to identify how
changes in several variables can impact the presence
and variability, of effluent toxicity. Table B-2 presents
B-1
-------
Table B-1. PPR Data Sheet
1. Industry Name
Notes:
2. Address
Notes:
3. Industrial Category (SIC Code)
Notes:
4. THE Objectives
Notes:
5. Manufactured Products
Notes:
6.
Chemicals Used
Notes:
a. Amounts (write on MSDS)
Notes:
b. MSDS
All Attached
Part. Avajjable
c. Process in which chemical is used
(write on each MSDS)
Notes:
d. Aquatic toxicity/bio
degradability information
on all chemical used. Review
MSDS, supplier information
and literature
Notes:
None
Some
7. Engineering drawings of facility
Notes:
a. Production flowchart
and line schematic
Notes:
'Available
No
b. All floor and process drains
with schematic
Notes:
Available
No
c. Wastewater pretreatment
system schematic
Notes:
Available
No
B-2
-------
Table B-1. Continued
8.
Facility Records
Notes:
a. Water usage, water bills
Notes:
Available
No
b. Discharge monitoring
reports for 24 months
Notes:
Available
No
c. Pretreatment system
operations data
Notes:
Available
No
d. Pretreatment system
operator interview
Notes:
Available
No
e. Spill prevention
control plan
Notes:
Available
No
f. RCRA reports, hazardous
waste manifests
Notes:
Available
No
Table B-2. Data Sheet for Regression Analysis
Month
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
1
LBS
0.80
1.01
1.20
1.25
1.16
0.90
0.90
1.20
1.30
1.27
1.10
0.90
2
INFLOW
1.2
1.5
1.7
1.7
1.6
1.2
1.2
1.6
1.8
1.7
1.6
1.2
3
OFLOW
1.0
1.2
1.4
1.5
1.4
1.0
0.9
1.4
1.6
1.4
1.4
1.0
4
COD
30
33
41
39
30
28
25
23
25
26
30
40
5
BOD5
10
11
15
14
12
11
10
9
15
18
17
21
6
CU
0.73
0.61
0.78
0.65
0.66
0.68
0.71
0.72
0.69
0.72
0.71
0.75
7
CR
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
8
ZN
1.6
1.9
2.0
1.6
1.5
1.4
1.8
1.9
2.0
2.1
1.9
2.0
9
LC50
20
20
18
18
22
30
40
38
40
33
28
22
B-3
-------
an example data sheet for a POTW serving one
manufacturing plant. In this example, only a few
POTW effluent industry variables were used in the
linear regression analysis; however, additional
variables could also be added in the regression
analysis.
The following variables are the "X" variables:
Industry variables:
IBS = Manufactured product per month
(millions of pounds)
INFLOW = Discharge flow based on water
usage (mgd)
POTW effluent variables:
OFLOW = Recorded effluent flow (mgd)
COD = Chemical Oxygen Demand (mg/l)
BODs = Biochemical Oxygen Demand (mg/l)
CU = Copper (mg/l)
OR = Chromium (mg/l)
ZN = Zinc (mg/l)
The following variable is the "Y" variable:
LCgo = Acute LC5Q as % effluent
By applying standard stepwise linear regression, the
variables OFLOW, BOD5, CR and CU were
eliminated because they were insignificant to toxicity.
Stepwise linear regression showed that the remaining
(X) variables were significant as regressed versus (Y)
LCsrj. This analysis indicated that ZN, COD, LBS,
and INFLOW were correlated with POTW effluent
toxicity.
Identify Source(s) of Toxicity
Based on the data analysis, a list can be developed
of the possible contributors to effluent toxicity at the
POTW. Of the potential toxicity control options, toxic
chemical substitution or elimination is usually the
most pragmatic approach. Thus, a followup interview
with the toxic discharger(s) should be conducted to
develop information concerning techniques for the
preferred use of problem chemicals. A list of useful
interview questions is shown in Table B-3. These
questions may enable the industry to identify problem
areas and possible corrective actions in the use of
toxic chemicals in manufacturing.
Recommend Toxicity Control Option(s)
Based on the results, it may be possible to
recommend several conceptual approaches to
controlling toxicity. Toxicity control may be practiced
at the industrial facility or at the POTW. Source
control may include substitution or elimination of
problem chemicals, flow reduction, equalization, spill
control, and manufacturing process changes. If
modifications in the POTW are recommended,
treatability studies will be required.
Table B-3. Summary of the PPR Chemical Optimization Procedure
Objectives
A. Optimize chemical usage amounts in production and water treatment processes.
B. Optimize chemical structures in process chemicals insuring biodegradability or detoxification is possible.
C Establish process controls over incoming raw materials, measuring possible toxic components. Example, corrosion-
resistant finish put on steel by manufacturer which must be removed prior to part fabrication.
Strategy
A. Determine what the role of each chemical is in the process. This is done by supplier interviews and review of data
gathered during the initial survey. Ask the questions:
Can less of this chemical be used?
Has the optimum amount been determined for each process?
Do other suppliers offer compounds that will perform as well at lesser concentrations?
Is the compound in reality a part of the manufacturer's water treatment system and independent of product production?
OBJECTIVE: Use less chemicals per pound of product produced.
(continued)
B-4
-------
Table B-3. Continued
B. Discover the biodegradability and toxicity of the process chemical. This is done by supplier interview, review of MSDS
information, and literature search. Suppliers may not want to supply exact chemical formulations. In this case, ask industry
to request supplier to perform tests to develop needed data. Questions to ask:
What are the components in the product?
What is its aquatic toxicity?
Is the product biodegradable?
Are there other component chemicals on the market that meet manufacturing requirements, but are low in toxicity and
highly biodegradable?
OBJECTIVE: Use chemicals that will not create toxicity problems.
C. Establish process controls over incoming raw materials. Many raw materials have chemicals used in their manufacturing
which are removed in the production of the final product Many raw materials may have trace contaminants which may
cause toxic problems. Questions to ask:
What chemicals are used in the manufacturing of the raw material?
What are the residual amounts of these raw material contaminants or by-products?
Are there quality control procedures that measure the amounts of these chemicals?
What are the statistical process measures used in the monitoring of these chemicals in the raw materials?
If these chemicals are required to be removed before the raw materials can be used in manufacturing the final product
what purpose do the chemicals serve in raw material manufacturing?
Can they be eliminated?
Can they be made less toxic or more biodegradable?
OBJECTIVE: Understand all raw materials being used and encourage development of QA procedures to monitor toxic
chemicals removed during processing. ;
111. Outcome of Investigations
A. A list of all chemicals used in processing and manufacturing of products. Included will be the amounts used, why the
chemicals are used, and if optimization has been taken.
B. MSDS sheets for all chemicals used will be on file
C. A list of chemicals applied or used in the manufacturing of all raw materials will be on file under that raw material with the
• residual amounts noted if possible.
D. A list of all chemicals and raw materials purchased on a monthly basis and the amount of product produced.
OBJECTIVE: Hard information to be used in data analysis.
IV. Use of opportunities available due to past experience
A.
B.
With experience in various industries, certain chemicals will become "known"
manufacturing.
as typically used in some process of
These known compounds can be categorized and toxicity determinations made. Once found toxic, the first information the
industry must supply to the municipality conducting the TRE is whether or not these chemicals are used in its
manufacturing process, in raw materials, or in water treatment processes. , ,
C. Letters also are sent to raw material suppliers asking if these compounds are used in raw material production. If they are,
the supplier is asked to submit prototype alternative raw materials that do not contain these compounds.
D. This can be done at the beginning of the TRE as past experience identifies the "typical" chemicals. Indeed control
regulations also usually involve establishing limits for selected known toxics in industrial operations.
E. What is accomplished by this process can be remarkable. First, the supplier is alerted that these compounds can cause his
customers problems. This makes him search for an alternative raw material source that is free of these objectionable
chemicals. A successful market search reduces the market demand for contaminated or objectionable raw material.
Example: Total brominated toxic organics (TBTO) limits in North Carolina have eliminated TBTO biocides from being
applied to hosiery.
(continued)
B-5
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Table B-3. Continued
V. Tests to help assess toxicity/biodegradability on specialty formulated chemicals and mixtures and to help evaluate competitive
products.
A. BODs, BOD2rj
B. BOD5, BOD20 performed at LCso concentration with ET50 or LC50 concentration with ET50 or LC50 performed on settled
effluent from test.
C. COD before and after BOD50 and BOD2o at LC50, ET50 concentrations.
D. Estimate biodegradability by using BOD5 and COD tests and the calculation (BOD5 - COD)/COD x 100 of a 10 or 20
mg/l solutions of chemical. This can be repeated at a 20-day BOD.
E. Bkxnass Inhibition tests (detailed procedures in Section 6).
F. LCgg on products. Screening dilutions 1-10,000 ppm.
OBJECTIVE: Help industry determine relative biodegradability and toxicity of various raw materials, products, and by-
products.
References
Diehl, R. and S. Moore, 1987. Case History: A North
Carolina Municipal TRE. Toxicity Iden-
tification/Reduction Evaluation Workshop, Water
Pollution Control Federation Conference,
Philadelphia, Pennsylvania.
Draper and Smith. 1966. Step-wise Multiple
Regression: Applied Regression Analysis. John
Wiley and Sons, p. 178.
Kirk-Othmer. 1982. Encyclopedia of Chemical
Technology, Wiley Interscience.
Pielou. 1984. Cluster Analysis Techniques: The
Interpretation of Ecological Data, Wiley
Interscience.
Romesburg, H.C. 1984. Cluster Analysis for
Researchers. Lifetime Learning Publications.
Gelmont, California.
ftU.S. GOVERNMENT PRINTING OFFICE: 1989-648-163/87092
B-6
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