EPA/600/2-88/070
April 1989
Generalized Methodoloav for Conducting
Industrial
Toxicity Reduction Evaluations
(TREs)
J.A. Fava
D. Lindsay
W. H. Clement
R. Clark
G.M. DeGraeve
J.D. Cooney
Battelle Columbus Division
Stephen Hansen
S.R. Hansen and Associates
William Rue
E.A. Engineering Science and Technology, Inc.
Sam Moore
Burlington Research Inc.
Perry Lankford
Aware, Inc.
Contract Number
68-03-3248
Project Officer
Kenneth Dostal
The Chemicals and Chemical Product Branch
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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Disclaimer
The information in this document has been funded wholly or in part by the United
States Environmental Protection Agency under Contract 68-03-3248 to Battelle
Columbus Division. It has been subjected to the Agency's peer and administrative
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 for use.
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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.
The purpose of this document is to present guidance for the performance of Toxicity
Reduction Evaluations (TREs) at industrial facilities. This is accomplished by
presenting a generalized methodology for designing and conducting a TRE and 10
supporting case studies which illustrate various approaches that have been used in the
performance of TREs to date.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
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Abstract
The U.S. Environmental Protection Agency or state regulatory agencies, under the
Clean Water Act, can require industries which cannot achieve water quality based
effluent limitations specified in their NPDES permit to conduct a Toxicity Reduction
Evaluation (TRE). The objective of the TRE is to determine those actions necessary to
reduce the effluent's toxicity to acceptable levels. This approach was written to
describe a generalized methodology for the design and performance of a TRE at an
industrial facility. The generalized methodology was developed based on the insights
learned in completing 10 TRE case studies.
A six-tier approach was directed toward the reduction of toxicity of the whole effluent
rather than specific components within the effluent. A flow chart was designed as a
dichotomous key linking the phases in a systematic progression to achieve the final
result, which is an effluent that consistently meets the toxicity limitation assigned to
it. The six tiers include: 1) information and data acquisition; 2) an evaluation of
remedial actions to optimize the operation so as to reduce final effluent toxicity;
3) characterization/identification of the cause(s) of the final effluent toxicity;
4) identification of the source(s) of the toxicity in the facility; 5) identification and
evaluation of methods for reducing toxicity in the final effluent; and 6) follow-up of the
toxicity reduction to confirm that the toxicity limitation is met and maintained. The
10 completed TREs that provided the basis for the structure of the protocol are
appended as case studies and follow the same generalized format presented in the
protocol.
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Contents
Page
Disclaimer ii
Foreword iii
Abstract iv
Figures x
Tables xi
Glossary xii
Acknowledgments xiii
Section 1. Introduction 1-1
Purpose 1-1
Regulatory Framework 1-1
Objectives of a TRE 1-1
Available Approaches 1-1
Content of this Document 1-2
Flow-Chart Overview 1-3
Section 2. Information and Data Acquisition 2-1
Regulatory Information 2-1
Facility Monitoring Data 2-2
NPDES Monitoring Data 2-2
In-House Monitoring Data 2-2
State Agency Monitoring Data 2-2
Plant and Process Description 2-2
Process and Treatment Plant Descriptive Data 2-2
Physical/Chemical Monitoring Data 2-3
Analysis of Data 2-3
Section 3. Good Housekeeping 3-1
Initiation of the Housekeeping Study 3-1
Evaluation of Housekeeping Practices 3-3
Identification of Potential Problem Areas 3-4
Identification of Corrective Measures 3-4
Selection of Corrective Measures 3-5
Implementation of Corrective Measures 3-5
Follow-Up and Confirmation 3-5
Section 4. Treatment Plant Optimization 4-1
Identification of Available Information 4-1
Identification and Evaluation of Influent Wastestreams 4-2
Description of Treatment System 4-3
Analysis of Treatment System Operation 4-3
Implementation of Corrective Action 4-4
Follow-Up and Confirmation 4-5
Section 5. Chemical Optimization 5-1
Information Gathering 5-1
Process Chemical Review 5-2
Review MSDS Information 5-3
Chemical Composition Screen of Incoming Raw Materials 5-3
Outcome of the Chemical Optimization Phase 5-3
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Contents (continued)
Page
Data Analysis 5-4
Follow-Up and Confirmation 5-4
Section 6. Toxicity Identification Evaluation (TIE) 6-1
Phase I - Toxicity Characterization Procedures 6-1
Components of Variability 6-3
Determining the Number and Timing of Samples 6-3
Toxicity Testing Procedures 6-3
Description of Characterization Methods 6-4
Quality Assurance/Quality Control 6-5
Phase II - Identification of Specific Toxicants 6-5
Phase III -Confirmation of Identifications 6-6
Section 7. Source Identification Evaluation 7-1
Setting the Initial Search Image 7-2
Sample Collection from the Influent Streams or Selected Process Streams 7-2
Chemical Specific Analyses for Tracking to Toxicant Sources 7-2
Evaluate Treatment Effects on Identified Toxicants. 7-4
Use Bench Scale Model to SimulateTreatment Plant Degradation and Track
Toxicity to Source Streams 7-4
Characterize the Toxicity of Suspect Source Streams 7-5
Further Upstream Investigations 7-6
Section 8. Toxicity Reduction Methodologies 8-1
Source Reduction 8-1
Waste Treatment Operations Improvements 8-2
Evaluation of Alternative Reduction Methodologies 8-3
Selection of Reduction Methodology 8-5
Implementation of the Solution 8-5
Follow-Up and Confirmation 8-5
Section 9. Follow-Up and Confirmation 9-1
Section 10. References 10-1
Appendix A: TRE Case Summaries A-l
Introduction A-l
Section A-l Case History: A Multipurpose Specialty Chemical Plant (MSCP) in Virginia .... A-3
Introduction A-3
Initial Data and Information Acquisition A-3
Toxicity Identification Evaluation (TIE) A-4
Effluent Toxicity A-4
Characterization and Fractionation - Causative Agent Identification A-4
Source Investigation A-5
Confirmation of Source or Agent A-5
Toxicity Reduction Approaches A-6
Treatability Evaluations A-7
Other Methods Examined A-7
Basis for Selection of Method A-7
Follow-Up and Confirmation A-7
Effectiveness of Solution A-7
Final Comments, Recomm.e.B.datiaiM., arvd Conchis-i/Mxa A-7
Problems Encountered A-7
References A-7
Section A-2 Case History: Tosco Corporation's Avon Refinery, Martinez, California A-9
Initial Data and Information Acquisition A-9
Toxicity Identification Evaluation (TIE) A-9
vi
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Contents (continued)
Page
Selection of a Monitoring Tool A-9
Chemical Fractionation A-11
Single Chemical Analyses A-11
Source Investigation Study for Toxicity A-12
Toxicity Reduction Through the Existing Treatment System A-12
Process Stream Evaluation A-12
Biodegradability of Process Stream Toxicity A-13
Toxicity Reduction Approaches A-13
Follow-Up and Confirmation A-14
Problems Encountered A-14
References A-J.T1
Section A-3 Case History: Martinez Manufacturing Complex, Shell Oil Company A-15
Introduction A-15
Initial Data and Information Acquisition A-15
Plant Description A-15
Toxicity Identification Evaluation (TIE) A-15
Characterization and Fractionation A-15
Confirmation of Toxic Agents A-17
Toxicity Reduction Approaches A-17
Oil and Grease A-17
Ammonia A-17
Amines (Organic Nitrogen) A-17
Flocculation Polymers (PEI and DMAEM/AM) A-18
Suspended Solids A-18
Follow-Up and Confirmation A-18
Problems Encountered A-18
Water Quality-Based Toxicity Limit A-18
References A-lo
Section A-4 Case History: A North Carolina Textile Mill A-21
Introduction A-21
Initial Data and Information Acquisition A-21
Process Description A-21
Wastewater Treatment Plant Description A-21
Characteristics of Influent and Effluent A-21
Toxicity Reduction Evaluation (TRE) A-21
Effluent Toxicity A-21
Characterization and Fractionation A-22
Toxicity Reduction Approaches A-23
Metals Reduction Experiment A-23
Extended Biological Treatment Experiment A-23
Conclusions: Toxicity Reduction Experiments A-24
Implementation of Toxicity Reduction Recommendations A-24
Follow-Up and Confirmation A-25
Problems Encountered A-25
References A-AO
Section A-5 Case History: A North Carolina Metal Product Manufacturer A-27
Introduction A-27
Initial Data and Information Acquisition A-27
Process Description A-27
Wastewater Treatment Plant Description A-27
Housekeeping A-27
Characteristics of Influent and Effluent A-27
Chemical Usage Review A-27
VII
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Contents (continued)
Page
On-site Visit A-28
Toxicity Identification Evaluation (TIE) A-28
Effluent Toxicity A-28
Characterization and Fractionation A-28
Metal and Toxicity Reduction Experiments A-29
Field Application of Laboratory Procedures A-30
Toxicity Characterization Procedures A-30
Receiving Stream Effluent Concentrations A-31
Conclusions and Recommendations for Toxicity Reduction A-31
Follow-Up and Confirmation A-31
References A-31
Section A-6 Case History: Texas Instruments Facility in Attleboro, Massachusetts A-33
Introduction A-33
Initial Data and Information Acquisition A-33
Toxicity Identification Evaluation (TIE) A-33
Effluent Toxicity A-33
Characterization of the Effluent A-33
Toxicity Reduction Approaches A-35
Pilot Testing A-36
Conclusions, Comments, and Recommendations A-36
References A-36
Section A-7 Case History: Chemical Plant I A-37
Introduction A-37
Initial Data and Information Acquisition A-37
Toxicity Identification Evaluation (TIE) A-37
Toxicity Screening A-37
Toxicity Reduction Approaches A-39
Source Reduction A-39
Powdered Activated Carbon Treatment (PACT) A-40
Granular Activated Carbon (GAG) Adsorption A-40
Ozonation A-40
Basis for Selection of Method A-40
Follow-Up and Confirmation A-41
Problems Encountered A-41
Recommendations, Comments and Conclusions A-41
Reference A-41
Section A-8 Case History: Chemical Plant II A-43
Introduction A-43
Initial Data and Information Acquisition A-43
Plant or Process Description A-43
Effluent Toxicity A-43
Evaluation of Treatment Process Optimization A-43
Toxicity Identification Evaluation (TIE) A-43
Causative Agent Identification A-43
Confirmation of Source or Agent A-45
Treatability Evaluations A-45
Source Treatment A-45
End-of-Pipe Treatment A-45
Final Comments, Recommendations and Conclusions A-45
Section A-9 Case History: TRE of I.T.T. Effluent A-47
Introduction A-47
Initial Data and Information Acquisition A-47
Plant Description A-47
VIM
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Contents (continued)
Page
Characteristics of Effluent A-47
Toxicity Identification Evaluation (TIE) A-47
Data Collection and Methods A-47
Other toxicity tests A-48
Effluent Toxicity A-48
Characterization and Fractionation A-49
Confirmation of Causative Agent A-49
Toxicity Reduction Approaches A-51
Treatability Evaluation A-51
Air Stripping A-51
Nitrification - Denitrification A-51
Problems Encountered A-51
References A-oz
Section A-10 Case History: Monsanto Chemical Manufacturing Facility A-53
Introduction A-53
Initial Data and Information Acquisition A-53
Sitel A-53
Site2 A-53
Site 3 A-53
Toxicity Identification Evaluation (TIE) A-53
Sitel A-54
Site2 A-54
Site 3 A-55
Toxicity Reduction Approaches A-56
Sitel A-56
Site2 A-56
Site3 A-56
Follow-Up and Confirmation A-56
Site 2 A-56
Problems Encountered A-56
Site 1 A-56
References A-56
IX
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Figures
Page
Figure 1.1. Overview of the water quality-based toxics control process 1-2
Figure 1.2. Toxicity Reduction Evaluation (TRE) flow chart 1-4
Figure 3.1. Good housekeeping logic flow diagram 3-2
Figure 4.1. Treatment plant optimization logic flow diagram 4-2
Figure 5.1. Chemical optimization flow chart 5-2
Figure 6.1. Toxicity Identification Evaluation (TIE) strategy flow chart 6-2
Figure 7.1. Source identification evaluation flow chart 7-3
Figure Al-1. Multi-purpose specialty chemical waste flow diagram A-4
Figure A2-1. Conceptual diagram of Tosco's wastewater treatment system with
designation of sites sampled during various elements of this study A-10
Figure A4-1. Early TRE 48-hour D. pulex acute static bioassay history, Glen Raven Mills. . A-22
Figure A4-2a. Pre- and post- TRE 48-hour D. pulex acute static bioassay history,
Glen Raven MiUs A-25
Figure A4-2b. Pre- and post-TRE monthly average effluent flow (MOD),
Glen Raven Mills A-25
Figure A5-la. 48-hour daphnid acute static bioassay history, Halstead Metal Products A-30
Figure A5-lb. Total recoverable copper concentrations, corresponding composite effluents .. A-30
Figure A6-1. Texas Instruments Attleboro outfall locations A-34
Figure A7-1. Waste treatment plant process flow diagram A-38
Figure A8-1. Wastewater flow and treatment schematic A-44
Figure A9-1. A schematic diagram of the processes in the I.T.T.
Rayonier wastewater treatment system A-48
Figure A9-2. Number of cystocarps for Champiaparvula (as % of control) plotted against
% effluent A-51
Figure A10-1 ESC effluent fractionation and testing scheme A-54
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Tables
Page
Table 2.1. Checklist of Useful Facility Specific Data 2-1
Table 8-1. Effluent Levels Achievable in Heavy Metal Removals 8-3
Table 8.2. Relative Biodegradability of Certain Organic Compounds 8-4
Table 8.3. Activated Carbon Treatment of Selected Compounds 8-4
Table 8.4. Air Stripping of Selected Compounds 8-4
Table Al-1. Summary of Toxicity Data on Final Effluent Samples Collected at Site No. 1 .. A-6
Table A4- 1. Effluent Characterization, Glen Raven Mills TRE,
Prechlorination Composite of December 17-18,1985 A-23
Table A5-1. Influent and Effluent Data Summary, Halstead
Metal Products, August 1985 - November 1986 A-27
Table A6-1. Range of Daphnia pulex LCSO's and NOAEL A-34
Table A6-2. Summary of Results From Representative Acute and Chronic
Effluent Toxicity Tests, Texas Instruments Toxicity Reduction
Evaluation August 1985 A-35
Table AY- 1. Typical Classification Results of Wastewater Sources A-39
Table A7-2. Treatability and Toxicity Factors from Identified Wastestreams A-39
Table A8- 1. Comparison of Reactor Performance A-44
Table A9-1. Additional Wastewater Characteristics During May 14-21, 1986 A-48
Table A9-2. Description of I.T.T. Rayonier On-Site Samples A-48
Table A9-3. Toxicity and Ammonia for I.T.T. Rayonier Effluent Samples A-50
XI
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Glossary
The following terms and abbreviations are used in this document:
BMP Best Management Practices
BOD Biological oxygen demand
COD Chemical oxygen demand
CWA Clean Water Act
DOT U.S. Department of Transportation
EDTA Ethylenediaminetetraacetic acid
MSDS Material safety data sheet
NOEL No observable effect levels
NPDES National Pollutant Discharge Elimination System
OSHA Occupational Safety and Health Administration
RCRA Resource Conservation and Recovery Act
SIC Standard industrial classification
SIE Source identification evaluation
TIE Toxicity identification evaluation
TOG Total organic carbon
TRE Toxicity reduction evaluation
TSD Technical support document for water quality-based
toxics control (U.S. EPA 1985)
TSS Total suspended solids
TU Toxicity unit
WWTP Wastewater treatment plant
XII
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Acknowledgments
Battelle Columbus Division (BCD) prepared this document for the Risk Reduction
Engineering Laboratory (RREL), U.S. Environmental Protection Agency, Cincinnati,
Ohio. Mr. Kenneth Dostal of RREL was the Project Officer. Principal contributors
include Dr. James A. Fava, Dr. William H. Clement and Daniel Lindsay, P.E. Other
contributors include Srinivas Krishnan, Dennis Mclntyre, Ron Clark, Dr. John D.
Cooney, and Dr. G. Michael DeGraeve, technical reviewer.
Battelle Columbus Division used the expertise of four subcontractors to prepare this
document. Principal contributors include Dr. Stephen R. Hansen of S. R. Hansen and
Associates and William Rue of EA Engineering, Science and Technology, Inc. Other
contributors include Samuel B. Moore of Burlington Research, Inc., and Perry
Lankford, P.E., of Aware, Inc. Ms. Linda Anderson-Carnahan, Region V, U.S.
Environmental Protection Agency, Dr. Philip Dorn of Shell Development Corporation,
and Dr. Donald Grothe of Monsanto Corporation are acknowledged for their valuable
contributions and as technical reviewers.
Mr. John Cannell of the Permits Division, U.S. Environmental Protection Agency
served as the Agency's principal technical reviewer and contributed significantly to
the development of this document.
The efforts and encouragement of William F. Brandes with the Permits Division are
acknowledged.
Xlll
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Section I
Introduction
Purpose
The purpose of this document is to present guidance
for the performance of Toxicity Reduction
Evaluations (TREs) at industrial facilities. This is
accomplished by presenting a generalized
methodology for designing and conducting a TRE and
is supported with case studies which illustrate
various approaches that have been used in the
performance of TREs to date. A synthesis of the
methods and approaches employed in these case
studies provided the basis for the generalized
methodology.
This document is intended for use by industrial
facilities that are required to perform a TRE.
Permitting agencies may also use this document for
reviewing plans submitted by regulated industries.
In addition, supporting organizations that are
preparing a site-specific TRE plan or conducting a
TRE may use this document as a guide.
Regulatory Framework
On March 9, 1984, the U.S. Environmental
Protection Agency (EPA) published a national policy
statement entitled "Policy for the Development of
Water Quality-Based Permit Limitation for Toxic
Pollutants (U.S. EPA 1984). To implement the policy,
EPA issued the Technical Support Document (TSD)
for Water Quality-Based Toxics Control (U.S. EPA
1985a). The TSD presented procedural
recommendations for identifying, analyzing, and
controlling adverse water quality impacts caused by
the discharge of toxic pollutants.
The overall process that one might go through to
evaluate the potential impacts of an effluent
discharge to an aquatic environment and the need to
establish additional water quality based toxic
controls is shown in Figure 1.1. This schematic
illustrates the steps to be taken, from definition of
water quality objectives, criteria, and standards, to
the setting of the final permit conditions with
monitoring requirements. When National Pollutant
Discharge Elimination System (NPDES) permittees
cannot achieve effluent limitations for toxicity, EPA
or a state regulatory authority may require the
discharger to conduct a Toxicity Reduction
Evaluation. The legal basis for requiring TREs is
discussed in the Permit Writer's Guide to Water-
Quality-Based Permitting for Toxic Pollutants (U.S.
EPA 1987a)
Objectives of a IRE
A TRE is an evaluation intended to determine those
actions necessary to achieve compliance with water
quality-based effluent limits (i.e., reducing an
effluent's toxicity or chemical concentration(s) to
acceptable levels). Water quality-based limits (i.e.
the regulatory target) could include limits on whole
effluent acute or chronic toxicity, and/or limits on
individual chemical constituents. These limits are
intended to protect beneficial uses of waterbodies,
and consider factors such as dilution, environmental
fate, and the sensitivity of the resident aquatic
community. The TRE may identify a remedial action
as simple as improved "housekeeping" procedures or
the need to modify the operation of a component of
the wastewater treatment system. On the other hand,
for complex facilities with numerous and variable
wastestreams, a TRE may involve a more extensive
investigation to identify toxicant(s) of concern and/or
cost-effective treatment or source reduction options.
Available Approaches
This document describes how to design and perform a
TRE at an industrial facility. Other documents which
provide guidance for performing specific components
of this overall process are:
EPAs Technical Support Document for Water
Quality-Based Toxics Control. Office of Water,
Washington, D.C., pages 57-58 (1985a).
EPAs Permit Writer's Guide to Water Quality-
Based Permitting for Toxic Pollutants. Office of
Water, Washington, D.C., pages 43-54 (1987).
EPAs Toxicity Reduction Evaluation Protocol for
Municipal Wastewater Treatment Plants.
November 1989.
1-1
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Define water quality objectives, criteria, and standards
Set permit limits directly
Establish priority water bodies
Generate data
Screen for individual chemicals
including potential
bioaccuniulative, carcinogenic, or
inutagenic chemicals
Collect definitive data for specific
chemicals
Screen for effluent toxicity
Collect definitive data
for effluent toxicity
Evaluate exposure (Critical flow, fate
modeling, and mixing) and calculate
wasteload allocation
Define required discharge characteristics
by the wasteload allocation
Derive permit requirements
Evaluate toxicity reduction
Final permit with monitoring requirements
Figure 1.1. Overview of the water quality-based toxics control process. Source: U.S. EPA (1985a)
EPA's Methods for Aquatic Toxicity
Identification Evaluations: Phase I - Toxicity
Characterization Procedures. September 1988.
EPA's Methods for Aquatic Toxicity
Identification Evaluations: Phase II - Toxicity
Identification Procedures. November 1989.
EPA's Methods for Aquatic Toxicity
Identification Evaluations: Phase III - Toxicity
Confirmation Procedures. November 1989.
In addition to these documents, other references
which describe specific methods for conducting
aquatic bioassays, chemical analyses, engineering
evaluations, and other components relevant to
conducting a TRE are identified in subsequent
sections of this document.
Content of this Document
This document presents a generalized methodology
for designing and performing a TRE at an industrial
facility. This methodology is primarily directed
towards compliance with whole effluent toxicity
limits rather than limits for individual chemicals.
This approach is taken because in some cases control
of whole effluent toxicity may be quite complicated
and would greatly benefit from generalized
methodological guidance. On the other hand, more
information is available on the control of single
chemicals with the main effort geared towards either
application of available treatment methodologies and
1-2
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development of new methodologies to control a
discrete constituent or process chemical substitution.
Because of the numerous differences in operations
and complexity of industrial facilities, in the
characteristics and variability of their effluents (both
chemical and lexicological), and in existing
wastewater treatment systems, flexibility in the
design and performance of a TRE is essential, and the
approaches utilized must be facility-specific. As a
result, the industrial TRE methodology presented in
the following sections is intended to describe
generalized approaches, which are represented by
those procedures that have been used successfully to
date.
It should be emphasized that the overall objective of
this generalized methodology is to provide the
framework and guidance on how to conduct a TRE. It
is not intended to be a "cookbook". There are
elements of this methodology which will not apply in
all industrial TREs, Users of this document are
encouraged to apply these approaches as analytical
tools where appropriate, and to tailor the
methodology according to site-specific deter-
minations and circumstances. Experience to date has
also demonstrated that clear communication between
the industrial facility, the permitting authority, and
contractors involved in conducting the TRE. This is
important in understanding the objectives and goals
for the TRE, establishing a reasonable schedule, and
in reporting the progress and results during the time
the TRE is being conducted.
(both chemical and biological) which may provide
information on the toxicity of the effluent. Third,
there is facility and process information which
describes the configuration and operation of the
facility. A synthesis of these three categories of
information is used to define study objectives,
identify what is already known, and possibly to
provide clues as to the causes and sources of toxicity.
This information may also suggest immediate actions
which may be useful in reducing final effluent
toxicity. The effectiveness of these actions can be
evaluated in subsequent tiers of the TRE.
The second tier of the TRE process is the evaluation
of remedial actions to optimize the operation of the
facility so as to reduce final effluent toxicity. Three
general areas of facility operation are considered:
general housekeeping, treatment plant operation,
and the selection and use of process and treatment
chemicals. These evaluations are discussed in detail
in Sections 3 through 5 of this document. For each of
these areas of concern, an evaluation is made to
determine if performance is optimal with regard to
toxicity reduction. This evaluation should be made to
identify obvious problem areas, plan and perform
remedial actions, and determine if these actions
reduce the final effluent toxicity to an acceptable
level. If the problem appears solved, a monitoring
program must still be initiated to confirm the
solution, and to ensure that the problem does not
recur. However, if these remedial actions fail to solve
the toxicity problem, the study will proceed into a
Toxicant Identification Evaluation (TIE).
How-Chaff Overview
A generalized flowchart for performing a TRE at an
industrial facility is presented in Figure 1-2. This
flowchart presents a conceptual overview of the TRE
process, illustrating how they might be linked, and
indicating when decision points are reached. Each of
the major components of the process are described in
detail in subsequent sections of this document.
However, in order to provide a general understanding
of how the entire process might work, a brief
overview of the TRE process is presented here.
The first tier of the TRE process is the acquisition of
available data and facility-specific information. This
phase is described in detail in Section 2 of this
document. The available information can generally
be divided into three categories. First, there is
regulatory information which specifies the events
leading up to the TRE, defines the regulatory
objectives of the study, and clearly identifies the
target for successful completion. In addition, the
regulatory agency may set compliance deadlines for
TRE completion, and specify intermediate dates for
completion of and reporting on specific portions of the
TRE. Second, there are effluent monitoring data
The third tier of the TRE process is the TIE which is
described in detail in Section 6 of this document. The
objective of the TIE is to characterize and identify the
cause(s) of final effluent toxicity. The evaluation can
use both characterization procedures and chemical-
specific analyses and, consequently, the
characterizations/identifications may range from
generic classes of toxic agents (e.g. non-polar
organics) to specific chemical compounds. Because
multiple samples are required to perform this tier, a
major objective of the TIE is to determine if, and how,
the cause of final effluent toxicity varies over time.
Once the TIE has been completed, the TRE process
can go in either of two directions. One approach is to
evaluate options for treating the final effluent, and
methods for accomplishing this are described in
Section 8. The other approach is to identify the
source(s) of final effluent toxicity and then evaluate
upstream (within plant) treatment options or process
modifications. The source identification element of
this second approach is described in Section 7 and the
treatment methods element in Section 8. These two
approaches are not necessarily mutually exclusive.
In fact, a decision can be made to pursue both
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TRE Objective - Definition
Goals
Triggers
Effluent and Influent
Monitoring Data
Information and
Data Acquisition
Plant and
Process Description
Toxicity Treatability Approach
Causative Agent Approach
Source
Identification Evaluation
Evaluation of
Treating Final Effluent
Toxicity Reduction
Method Evaluation
Tier I
Evaluation of Chemical Use
Evaluation of
Treatment System
Evaluation of
Facility Housekeeping
Did
Treatment System
Corrections Reduce
Toxicity ?
Did
Housekee,uirj,a
Improvements Reduce
Toxicity ?
Uid Chemical
Replacements Reduce
Toxicity ?
Toxicity Identification Evaluation (TIE)
Tier II
Evaluation of Source Control/
Treating Process Streams
Selection and Method Implementation
Follow-up and Confirmation
Tier IE
Tier IV
TierV
1
Tier VI
Figure 1.2. Toxicity Reduction Evaulation (TRE) flow chart.
1-4
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approaches simultaneously, and then to select the
most technically and economically attractive option.
The source identification evaluation (SIE) is the
fourth tier in the TRE process. The objective of this
evaluation is to identify those process streams which
are significant sources of final effluent toxicity. A
first step in the SIE may be to review the information
and data collected on the causes of final effluent
toxicity. This synthesis forms a search image for
upstream sources. The subsequent approach would
depend upon the specificity of this search image. If a
specific toxic chemical has been identified as the
causative agent, the SIE would be straightforward
and have a high probability of success. It would
involve the chemical analysis of process streams for
the identified causative agent or its parent
compound(s). Those process streams which contain
the causative agent in sufficient concentrations
would clearly be designated as sources of final
effluent toxicity. On the other hand, if the search
image is more general (e.g., a class of toxic
compounds), the SIE may be more complicated. It
would include the determination of the
characteristics of the toxicity in the process streams
feeding into the wastewater treatment system. A
comparison of process stream characteristics against
the search image would then be used to identify those
process streams which are prime suspects as the
source(s) of final effluent toxicity. In either case, the
treatability or application of other control methods to
these process streams would then be evaluated and
the effectiveness confirmed according to methods
described in Tier V (Section 8).
The evaluation of toxicity reduction methods, the
fifth tier of the TRE process, is described in Section 8.
The objective of this tier is to identify methods for
reducing toxicity in the final effluent and/or source
streams. Each method would be evaluated for
technical and economic feasibility and the most
effective method would be selected and implemented.
Follow-up and confirmation is the sixth and final tier
of the TRE process and is described in Section 9. This
tier becomes operative after the selected method for
toxicity reduction has been implemented. Once the
selected toxicity reduction alternative has been
implemented, continued effluent toxicity testing over
time is important to confirm that the toxicity target
has been achieved and is being maintained.
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Section 2
Information and Data Acquisition
The first step (Tier I) in performing a TRE should be
the collection and analysis of any available
information and data which might prove useful in
designing the best directed and most cost-effective
study for the facility under consideration. The
pertinent information that is generally available
falls into three categories:
the regulatory information which describes why
the TRE is being required and what objectives
are to be met (the NPDES permit requirement
and schedule, for example);
the effluent monitoring data which describe the
toxicity and physical/chemical nature of the final
effluent; and
plant and process information which describes
the physical layout of the plant, the processes in
operation, and the physical/chemical nature of
process wastewaters.
The amount of available information may be
surprisingly large and a careful review followed by
judicious use of selected analyses could provide
valuable insight into the possible cause(s) and
source(s) of toxicity, This information will help define
an appropriate TRE program and, in some cases, may
lead to a quick solution to the toxicity problem. An
example of a possible checklist of data and
information which might be obtained from a. facility
during this step is presented in Table 2.1.
The ten case summaries presented in Appendix A
reviewed available data and regulatory objectives
prior to designing an investigative approach. Refer to
these case summaries for further illustration of the
acquisition and use of existing information.
Regulatory Information
As in any study, the probability of successfully
completing a TRE will be greatly enhanced by a clear
understanding of the objectives and goals before
designing and implementing the evaluation. Since
most TREs will be regulatory requirements, the
responsible regulatory authority, either EPA or the
state delegated with NPDES permitting authority,
Table 2.1. Checklist of Useful Facility Specific Data
1. Industry name:
2. Address:
3. Industrial category
4. TRE and TIE objectives:
5. Products produced:
6. Chemicals used:
a. Amounts
b. Material Safety Data Sheets (MSDS)
c. Process in which chemical is used
d. Aquatic toxicity/biodegradability information on all
chemicals used and their breakdown products.
7. Engineering drawings of facility
a. All floor and process drains with schematics
b. Potable and wastewater line locations
c. Steam line, boiler locations, cooling tower locations
d. Wastewater Treatment Plant (WWTP) schematic
e. Production flowchart and line schematic
8. Facility records
a. Water usage, water bills
b. NPDES or monitoring reports for 24 months
c. WWTP QA data reports
d. WWTP operator interview
e. WWTP flow recorder records
f. Complete toxicity test history
g. NPDES (or equivalent) permit
will set the appropriate objective or target for a TRE.
A discharger will normally be required to conduct a
TRE as a result of a violation of a whole effluent
toxicity permit limit. In this case, the goal of the TRE
will be achieving a level of effluent toxicity which
meets the applicable permit limit. In other cases a
TRE may be required where no whole effluent
toxicity limit currently exists in the permit, but
available effluent toxicity monitoring data indicate
that water quality standards would be violated. In
these situations, the goal of the TRE would be
achieving the level of effluent toxicity which will
meet a limit, which would protect the state standard,
when it is placed in the permit. It is essential that the
discharger has a clear understanding of both the
whole effluent toxicity limit that they are required to
meet and the toxicity test endpoint which will be used
to demonstrate achievement of the TRE objective or
target.
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The determination of what discharger monitoring
results are sufficient for requiring a TRE will be
made by the regulatory authority on a site-specific
basis. Where it is appropriate, more extensive
effluent toxicity testing may be required prior to, or
as the initial step of, the TRE. It should be noted that
where the results of a TRE identify a specific
pollutant as the cause of effluent toxicity, a chemical
specific limit may be added to the permit to control
this toxicant.
While the regulatory authority can specify the
monitoring results that trigger a TRE, the objective
or permit limit which, is to be achieved, and the
schedule for conducting the TRE, the discharger is
solely responsible for designing and conducting the
TRE to meet the specified objective. The submission
of a TRE plan for review by the regulatory authority
prior to conducting the evaluation will facilitate the
successful completion of the TRE and ensure that the
objectives, endpoints and recommended approaches
are clearly understood.
Facility Monitoring Data
Numerous sources of information are available
concerning the quality and quantity of a facility's
effluent. Three commonly available sources are:
NPDES monitoring data (see Sections A7 and A9),
in-plant supplemental monitoring data, and state
agency monitoring data. Review and analysis of each
of these should prove useful in the design of a TRE
program and could provide information helpful in
understanding the magnitude of the toxicity, toxicity
variability over time, possible causative agents, and
an appropriate toxicity monitoring tool.
Another possible use of the available effluent
monitoring could be the identification of a cost-
effective monitoring test for use in the TRE study.
Effluent bio monitoring usually tests the effluent's
toxicity using several species. A review of these
results could allow for. the ranking of the tests
according to sensitivity, speed, and cost. If several
species are similarly sensitive, it may be possible to
select the quickest and cheapest test as the routine
monitoring tool for the TRE.
NPDES Monitoring Data
One possible source of information is the NPDES
monitoring data which are routinely generated at the
facility. This database usually provides a long record
of the physical and chemical nature of the effluent.
Included in this record may be concentrations of a
number of single chemicals, BOD, COD, TOG, pH,
temperature, DO, and effluent toxicity data. Existing
chemical specific analyses and whole-effluent
toxicity test data could also prove useful in defining
how and why final effluent toxicity varies. Insights
as to the variability would aid in
designing the number and timing of samples to be
characterized in the toxicity identification evaluation
(TIE) tier of the TRE. If toxicity data are available, it
might be possible to perform multivariate analysis to
identify those parameters which are positively
correlated with toxicity. This is done in case
summaries A-3, A-8, and A-9. If a single chemical is
highly correlated, it could be considered a potential
suspect as the causative agent and the results of the
TIE would then be used to evaluate and confirm the
accuracy of that suspicion.
In-House Monitoring Data
Many industrial facilities perform more frequent and
more detailed chemical analyses on their final
effluent than are required in the NPDES permit.
These additional data may be used for in-house
evaluation of treatment plant operation, or perhaps
in an attempt to identify current or potential
problems. If toxicity test data are available,
performance of multivariate analysis may identify
chemical or physical parameters which are correlated
with toxicity. As with the NPDES data, this effort
may lead to a suspect causative agent or toxicity
source and to the selection of a more cost-effective
and rapid toxicity testing tool.
State Agency Monitoring Data
Frequently state agencies will have performed
toxicity tests and selected chemical analyses on the
effluent being evaluated. This information might
also be useful in the investigation.
P/ant and Process Description
One of the early steps of any TRE is to understand
how the facility is designed and operates. Relevant
information includes facility blueprints, process and
treatment plant descriptions, production timetables,
process and treatment stream monitoring data,
accident and upset reports, and turn-around
schedules. Review and evaluation of these data may
provide valuable insight as to the causes and sources
of final effluent toxicity and perhaps how to better
design the TRE study. Nearly all of the case
summaries reviewed in the Appendix contain this
step.
Process and Treatment Plant Descriptive Data
The configuration and general operating mode of
process units and the wastewater treatment system
can usually be determined based on a review of
facility blueprints and operational records.
Information on process streams which may prove
particularly useful in the early stages of a TRE are
the number and types of streams, their size, and
variability. Understanding the types of processes
which are performed at the facility may identify a
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suspect stream because of problems that have been
observed in the same or similar streams in other
facilities.
Knowledge of the scheduled changes or events in
process stream operation (i.e., batch, continuous, or
intermittent) when coupled with toxicity data may
provide strong evidence as to possible sources of final
effluent toxicity and the reasons for variability of
effluent toxicity. For example, assume that a
particular process is run as a three-day batch
operation once every two weeks; starting on Monday
and ending on Wednesday. A review of the toxicity
test results indicates that final effluent toxicity also
generally follows the same two week pattern. This
correlation would cause an investigator to further
evaluate this evidence. In addition, correlations
between turn-around schedules and toxicity could
prove very useful in determining suspect source
streams. If toxicity disappears while a process unit is
undergoing service and reappears when the unit is
back on line, a suspect stream has been identified and
this lead should be pursued. Similarly, it is often seen
that toxicity will increase when a unit starts up and
then decrease to background levels after a few hours
or days of operation. Good quality data from grab
samples may permit identification of this type of
phenomenon.
On the treatment system side, the information which
might prove the most useful in the early stages of a
TRE include the types and configuration of
equipment, flow equalization facilities, and records of
treatment plant upsets. Understanding the retention
time of the system should help in selecting the proper
frequency of testing required to detect effluent
variability in the toxicity identification evaluation
tier of the TRE. Correlations between plant upsets
and toxicity events would suggest that an
investigation of treatment plant operation should be
one of the first components of the TRE study.
Another potentially productive approach could be
correlations between season and toxicity. If such a
pattern has been observed, and operating data
indicate that the treatment system is less efficient
during the period when high toxicity is measured,
further evaluation of the treatment system may be
warranted.
exceed reported toxicological effect levels following
treatment. If these same compounds have been
identified in the final effluent, or if the scientific
literature indicates that they are not biodegradable,
it might be prudent to evaluate their role in final
effluent toxicity. If these compounds have not been
identified in the final effluent, it may be useful to
design a set of analyses into the toxicant
identification phase of the TRE which would be able
to detect these compounds or their toxic breakdown
products. It should be cautioned that TIE
experiments evaluating the fate of specific process
stream chemicals should only be initiated if there is
evidence supporting the suspected degradation
pathway, and the Phase I characterization results
support this suspicion. Otherwise, such an effort may
prove quite lengthy and hold little chance for success
since existing treatment may already reduce the
toxicity of these compounds.
Analysis of Data
In this section, several sources of data were identified
which specify concentrations of chemicals both in the
final effluent and in upstream sources. If toxicity
data are also available for the same sample, it may be
possible to perform correlation analyses between all
numeric variables and toxicity. The objectives would
be to identify those variables (i.e., constituents)
which are positively correlated with final effluent
toxicity. There are several data analysis techniques
available for performing these types of correlation
analyses including step-wise multiple regressions
and cluster analyses. In addition, software packages
make computer aided analysis quite user friendly.
References for available techniques and software are
presented in Table 2.2.
Table 2.2 Available Tools
Data Analysis Techniques
Drapper N.R., and H. Smith. Applied Regression Analyses,
John Wiley and Sons, New York, New York, pg. 178 (1966).
Pielou, EC. Cluster Analyses Techniques: The
Interpretation of Ecological Data. Wiley Interscience, New
York, New York (1987).
Infometrex, Inc. Arthur, Pattern Recognition Software,
Seattle, Washington (1986).
Physical/Chemical Monitoring Data
Most facilities maintain records of in-house
monitoring that is routinely performed at various
locations along the process and treatment streams.
This monitoring usually consists of physical and
chemical analyses performed to check on how well
the units are operating. These data can be useful in
identifying potential sources of final effluent toxicity.
Chemical analysis of process streams may identify
chemicals in concentrations which may
Any chemicals identified via these correlation
procedures would become candidates for further
evaluation. Many chemical and physical parameters
may be covarying in irregular and unpredictable
manners to mask the relationship between the
concentration of a single chemical and corresponding
toxicity test result. Rarely would one expect the
correlations to provide conclusive evidence of cause
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and effect. However, significantly positive
correlations may act as a pointer in the TRE process,
focusing attention to possible chemicals of concern,
and may be used to support the results of the TIE and
source evaluation.
As a cautionary note, it should be recognized that a
positive correlation between concentrations of a
single chemical and toxicity may prove to be a false
lead. Some chemicals may covary with the actual
toxicant and, therefore, be mistaken as the causative
agent. For example, emulsifiers are often added to
pesticide formulations to promote solubility and
facilitate application. The concentration of the
emulsifier may correlate perfectly with toxicity, but
it is probably not the toxic agent; in this case the
pesticide would be the likely culprit.
In order to protect against the possibility of false
positives, it is advisable to use Phase I Toxicity
Characterization Procedures as a check on positive
correlations (see Section 6). If characterization tests
which are selected to specifically remove the suspect
causative toxicant(s) (based on their
physical/chemical nature) fail to remove or
neutralize effluent toxicity, a false correlation is
likely. Implementation of this check may prevent
going down blind alleys when the TRE proceeds into
the identification of specific causative agents.
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Section 3
Good Housekeeping
Good housekeeping at an industrial facility covers
plant practices and operations which may directly or
indirectly affect effluent water quality. Factors
which are involved in this area include:
General facility cleanliness/tidiness;
Facility spill prevention and control;
Waste and materials storage areas;
Materials handling operations, including loading
stations, on-site transport, piping and valve
assemblies;
Waste handling and disposal operations; and
Run-on/run-off control.
A facility which practices good housekeeping will
reduce the chemical contributions which run-off,
spillage, and similar occurrences make to toxic
loading in the effluent stream.
This section investigates the individual elements of
good housekeeping at an industrial facility and
presents criteria by which these may be assessed.
Methods to identify corrective measures are
examined. Selection and implementation of
appropriate corrective measures, and follow-up
studies, round out the discussion. Throughout, it is
assumed that a preliminary survey will focus on
discovery and subsequent improvements. Figure 3.1
depicts schematically the steps involved in a good
housekeeping study. Examples of housekeeping
approaches are presented in Sections (Appendix) A-3,
A-4, and A-5. These case summaries contain
examples describing rerouting of waste streams,
evaluation of dye machine ratios, and installation of
simple drain traps to catch runoff materials.
Initiation of the Housekeeping Study
When unacceptable toxicity is identified in the
effluent, a housekeeping survey should be planned.
The intent of the survey is 1) to identify areas which
may be contributing to the observed toxicity and 2)
reduce these contributions through the use of best
management practices (BMPs), administrative and
procedural controls. Thus, low-cost, simple, direct
solutions are desired.
The first step of the study requires the assembly and
coordination of the study team, and the collection of
relevant plant information. This can often be
accomplished through a kick-off meeting at the plant
where the participants get together to discuss the
purpose and limits of the survey.
Housekeeping surveys tend to be somewhat
subjective in nature. In order to avoid possible
conflict between the survey team and plant
personnel, it should be clearly established that the
team is not seeking to uncover poor housekeeping but
rather to uncover practices which, whether good or
bad, may affect effluent toxicity. A clear
understanding should be established with plant
management and operations prior to the survey,
including:
the organizational channels which must be
followed to obtain authorization to make the
necessary changes;
the resources available from the plant to
investigate, define and implement an operational
or procedural change; and
the extent of justification required prior to
implementation, including the effect that a
particular action (or inaction) may have on
overall plant operations;
the cost and ease of implementation, and the
level of benefit expected.
The justification criteria should be general enough
that they may be applied to any plant area, yet
specific enough that they yield useful information to
the facility.
Survey team members should review plant
procedures, documented and otherwise, to assess the
level of importance placed on housekeeping. This will
include documentation review as well as
3-1
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Kickoff Meeting
with Plant /
Yes
Yes
r
No
I
f
Identify
Deficiencies
"
No
Effluent
Consistenly
Meets
ToKicity
Target Level
Reduction
in Effluent
Toxicity
No
Initiate Toxicity
Identification
Evaluation
Figure 3.1. Good housekeeping logic flow diagram.
interviews with various plant personnel. Suggested
sources of information include:
Spill prevention and control plans developed to
meet various regulatory requirements [CWA,
Resource Conservation and Recovery Act
(RCRA)];
RCRA facility documentation, including waste
handling and storage plans;
OSHA training documentation, which may
contain information on material handling
operations and procedures;
DOT related information, including any
developed specifically for the loading, unloading,
and transportation of materials and products to
and from the facility;
Plant blueprints, maps, etc. showing areas of
various plant operation, drainage systems, waste
collection, material storage and disposal
facilities, and,
Other information available at the plant which
may be relevant to the survey.
In addition to this information review, specific
individuals at the plant, who may, through years of
experience, have valuable insights into plant
operations affecting housekeeping, should be
identified. These individuals may include plant
foreman and supervisors, operations and
maintenance personnel, truck operators, material
handlers, etc. During the subsequent survey, these
individuals should be sought out and briefly
interviewed for both a capsule summary of current
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operations, and a historical perspective of plant
operations.
Evaluation of Housekeeping Practices
Once subject areas have been identified and relevant
information gathered, the actual survey can begin.
The survey approach presented below will be two-
phased; one being a review of plant policies and
procedures, the other being a "walk-through"
inspection. Areas included in the review and
inspection are:
Vehicle loading and unloading areas;
Diked Storage Areas;
Waste accumulation and handling areas;
Waste storage areas;
Raw materials storage and handling areas;
Process area and reactor cleaning/washdown
practices;
Laboratory areas, including laboratory waste
handling practices;
Above and below ground piping systems,
including vents, drains, cleanouts, valves, etc.;
Atmospheric venting practices and scrubber
operation;
Non-point source flow contributions, including
runoff, springs, and seeps;
Previously used waste disposal sites;
Process equipment and piping salvage area
runoff;
Controlled/permitted stack emissions; and
Routine maintenance practices.
The list developed for a particular facility will be
specific to that facility, and may include other factors
not listed above. Close coordination with site
personnel will assure that all major subject areas are
addressed.
Notice should be taken of areas subject to obvious or
previous release or spill instances. Raw materials,
intermediates, final products and wastestreams are
all included in this survey. Proximity of these areas
to overland flow paths, drainage channels, manholes,
etc., should be carefully noted. If necessary, runoff
patterns for the facility should be developed as an aid
in assessing potential impacts.
The release of accumulated water from diked bulk
storage areas presents another area for assessment.
Often, the criteria for release of accumulated
material is by visual inspection (coloration, floating
oil/debris, etc.). These criteria may not be appropriate
where the potentially toxic substances cannot be
visually detected.
Laboratory practices should also be examined,
especially where they may involve the disposal of
small quantities of materials on a routine or regular
basis. Both analytical and research laboratories
should be examined. Laboratories can often be the
source of small quantities of highly toxic materials,
which if improperly disposed, could have a major
impact on effluent quality.
Regular maintenance, process modifications, and
new process development should also be included in
the survey. Timely detection of leaking valves,loose
fittings, and deteriorated piping systems could have a
major impact on the overall cleanliness of the facility.
Corrected in a timely fashion, the impact of these
areas on the final discharge from the facility should
be negligible. On the other hand, if problems are not
detected and corrected quickly, significant impacts
are possible.
Atmospheric venting in process or material delivery
lines may release toxic substances to the atmosphere.
These may have opportunity to impact the effluent
through atmospheric deposition on building surfaces
and roadways, and subsequent wash-out during
rainfall events. Accumulation of small quantities of
substances over time may result in measurable
releases during and subsequent to rainfall events.
Probably the largest and most noticeable area of
concern involves waste and materials handling and
storage. These locations are often subject to other
permitting and administrative controls, such as
RCRA and NPDES requirements. Therefore,
housekeeping should generally be good. There is,
however, a possibility that certain areas (such as
final product loading) may slip through these
controls. An example would be the pumping of
stormwater from the tank containment area, which
has been slightly contaminated by a highly toxic,
nonbiodegradable substance. If such is the case, there
may be a need to address these areas during the
housekeeping survey.
When observed conditions are matched against the
established criteria, a decision must be made
whether to initiate housekeeping changes or not. To
aid in this decision, it may be advantageous for the
team to develop a grading checklist. The grading,
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like the survey, will be subjective. It should, however,
provide a basis upon which a decision to proceed with
certain activities can be made, and determine how
these activities may be prioritized with regard to
their effect upon meeting effluent discharge limits.
Identification of Potential Problem Areas
After completing the preliminary evaluation,
potential problem area identification should begin.
Potential problem areas may be identified by
examination of the following:
Probability of release of a toxic material;
Type and frequency of release which may occur;
Quantity of toxic substances involved;
Toxicity of substances released;
Potential downstream impact of the substances
released; and
Effect of release on final effluent quality.
These and other factors that may be identified in the
problem area should be weighed. This weighting may
contain both subjective and objective elements. For
instance, the likelihood of a release may be based on
an operator's perception of how often tanks are
overfilled (if no records are available), while the toxic
effect (in weight of toxicant per mass spilled) may
well be known. For example, the release of 1 unit of a
highly toxic material may be more crucial than the
release of 10 units of a mildly toxic material.
Included in this weighting should be some
consideration of the probable effect that a release
from a specific area may have on final effluent
toxicity. It may be that an area identified during the
survey in need of housekeeping improvements, may
not have any impact on final effluent toxicity. If
probable impact areas can be isolated from non-
impact areas, the completion of further studies can be
expedited.
Once the weighting process is complete, a relative
worth may be assigned to each problem area. This
may be accomplished by considering loss of productor
material, perceived harm to the environment, effort
needed for cleanup efforts, or other factors as may be
deemed appropriate. Factoring this relative worth
with the likelihood of a release will derive a
relationship by which to gauge the necessity of a
housekeeping improvement. Sites subject to the
housekeeping study may be ranked, with those
requiring immediate attention ranked above those of
lesser concern. After this ranking is completed, the
identification and selection of corrective measures
may begin.
If the housekeeping survey identifies no deficiencies,
the TRE should proceed on to the TIE component.
Identification of Corrective Measures
After potential problem areas have been identified,
appropriate corrective measures for these areas must
be examined. Probable corrective measures may
include:
Area cleanup; paving or containment;
Process or operational changes;
Material loss collection and recovery (see
Appendix Section A-5);
Chemical and biological testing of contained
waters prior to release from diked storage areas;
Increased storage capacity for contained waters
to avoid toxic "slugs" to the effluent during storm
events and washdowns of fire water system
usage; and
Equipment modifications or changes (see
Appendix Section A-3 and A-8).
Each corrective measure identified should be capable
of resolving a potential trouble spot without creating
an undue burden on plant operations. Cost
effectiveness and continuity of effectiveness should
also be of primary consideration. For example, an
initial cleanup of a product loading area may provide
immediate results. However, without changing the
loading procedures which resulted in the untidiness
in the first place, problems would recur. In this case,
the final solution would require a second stage - that
being a procedural change in the way material
loading occurs, or a material loss collection and
recovery system.
Housekeeping practices are normally acquired or
learned. They may suffer from the "tradition
syndrome" - operations which have always been
conducted in a particular manner, and which plant
personnel are unwilling or reluctant to change.
Retraining, refocusing, or re-emphasizing may be
necessary to reach the individuals involved. Other
times, housekeeping can be improved by initiating
new methods or procedures, where established
conduct has never been formalized. The process of
formalization may be sufficient to generate a positive
change.
Obviously, corrective measures would not be
required for areas with little or no potential for
affecting final effluent toxicity, although, once
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identified, the measures might be implemented for
other reasons. The probability of affecting a positive
change by the implementation of corrective
measures, as well as the willingness of plant
personnel to follow through with the required
changes once they have been identified should be
considered.
Selection of Corrective Measures
After appropriate corrective measures have been
identified, a solution must be selected from them. The
basis of the selection will include level of benefit,
consideration of cost, ease of implementation, and
timeliness of solution.
Most housekeeping solutions will carry a relatively
small price tag. This is because they will largely
involve procedural changes rather than physical or
equipment changes. Where physical changes are
involved the cost should be balanced against the
perceived benefit.
Ease of implementation should be considered in
selecting an appropriate solution. Obviously,
solutions which involve minimal procedural changes
and require little adjustment on the part of plant
personnel will generally be better received than those
which require substantial changes in the way a job is
conducted.
Timeliness of solution is another important
consideration. Those solutions which may be
initiated quickly and with a minimum of plant
interruption, will create a higher level of acceptance
from within the plant, and, therefore, a higher
probability of success.
Implementation of Corrective Measures
Once the appropriate measure has been identified,
the implementation phase should begin. This phase
should be carefully planned so as to maximize the use
of plant personnel and expertise, thereby positively
influencing acceptance of the program. As most
housekeeping improvements will include procedural
(Best Management Practices) rather than physical
changes, acceptance and involvement by plant
personnel is imperative for the continued success of
the program.
As much control as possible over the implementation
of the corrective measures should be placed in the
hands of plant personnel. This is important, since the
continued success of the correction will not be
measured by the first activity, but rather by
maintaining the positive correction.
In order to confirm adequately the effectiveness of the
corrective measure, toxicity tests and Phase I
characterization procedures should be conducted
before and after implementation. The results of these
tests will be useful for comparison with the follow-up
evaluation of effects.
Follow-Up and Confirmation
Once the solution has been implemented, follow-up
studies should be initiated (see Section 9). In
summary, follow-up on housekeeping studies would
include:
Continuation of implementation;
Evaluation and confirmation of effectiveness on
toxic releases (toxicity tests and Phase I
characterization);
Solution impact on affected operations; and
Rigidity of continued implementation.
The goal of the follow-up is to determine 1) whether
the solution as envisioned has had the planned
positive effect on the toxicity of the final effluent and
the management of this toxicity reduction;
2) whether the solutions were well received and
easily implemented by the plant personnel; and
3) whether operations would continue to have a
positive impact on toxicity reductions in the plant
effluent. Follow-up studies may also help to identify
additional areas of improvement which were not seen
in the original study.
If follow-up studies indicate that housekeeping
improvements have not resulted in the desired
toxicity reductions, then alternative solutions must
be developed. This may require a more detailed
identification of contributing {actors VSection %\ ani
investigation of source contributions (Section 7).
3-5
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Section 4
Treatment Plant Optimization
A critical element in reducing toxicity in an
industrial facility's effluent is the evaluation and
optimization of the facility wastewater treatment
plant. A well maintained plant, operating under
design conditions, may be capable of providing an
acceptable level of treatment for conventional or
design parameters, and still allow toxic compounds to
be released to the environment. On the other hand,
the same plant may be able to handle the majority of
toxics it encounters if adjustments are made which
allow operation of the treatment processes at other
than design conditions. The objective of this
optimization is to assure that the treatment plant is
operating in optimal fashion with respect to removal
of its design parameters. This will maximize the
probability that toxicity will also be removed.
The process of operational optimization begins with
the recognition that an effluent's toxicity exceeds
limits established by rule or permit. Plant operations
optimization runs simultaneous with housekeeping
improvements (Section 3) and chemical optimization
(Section 5). The plant optimization process is depicted
schematically in Figure 4.1, and its components are
described in detail in the remainder of this section.
As the optimization process begins, it may be helpful
to develop a checklist of parameters which bear
examination. This will be specific to the plant under
consideration and will be highly dependent upon the
information gained from various sources at the plant.
Sources of information might include plant personnel
(both active and retired), design, and construction
documents, and operating records (including influent
and effluent monitoring information).
This section discusses the steps required to critically
assess and optimize a treatment facility's operations.
This discussion is general in nature, providing an
overview of the operational parameters to be
considered and analytical techniques which might be
used. A program for the evaluation of a facility will
need to be based upon conditions specific to that
particular facility.
Case summaries presented in Appendix Sections A-3,
A-4, and A-8 all contain some aspects of treatment
plant optimization. In Appendix Section A-3, it was
determined that fluctuations in Nitrobacter bacteria
correlated with effluent toxicity, whereas, in
Appendix A-4, increased retention of wastewater in
the activated sludge basin would reduce effluent
toxicity. In case summary A-8, the use of activated
sludge from municipal treatment plants was
evaluated.
Identification of Available Information
Information of interest in this evaluation will deal
with the design and performance of the treatment
system. Plant design information includes a
description of the specific treatment units and how
they are linked, design capacity and loading rates,
and what the plant was intended to treat. In addition,
identification of design performance criteria will
prove useful in evaluating current operational
performance. This information may be available from
a number of sources, including system design
documentation, system modification documentation,
facility blueprints, plant operating and maintenance
procedures and protocols, and discussions with plant
personnel.
Performance information may be available for both
the overall treatment process and for each of the
component units. Of particular value are data on the
quality of all influent and effluent streams. This may
be available from monitoring reports and studies or
operational logs. Some facilities even have their data
in computer data bases.
After this information gathering is complete, the
optimization sequence may begin. This sequence will
include evaluation of the influent wastestreams,
description and evaluation of the treatment system,
and optimization of treatment operations. These
steps are described in the following sections.
Identification and Evaluation of Influent
Wastestreams
Changes in plant processes at a facility are likely to
result in changes in the influent to the treatment
plant. Consequently, the final wastestream may
contain components which were not in the original
4-1
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Identify Individual
Units in Treatment
System
Analyze .Unit
Operations Based
Upon Conventional
Parameters
System
Operating
Beyond Design
Parameters
Information
Acquisition
No
k
r
Identify Unit
Modifications Which
May Reduce
Toxicity
^
r
Initiate Corrective
Actions
^
w
c
Yes
>,
'
Initiate Toxicity
Identification
Eviibartbn
4
NO
Yes
Corrective
Actions Reduce
Final Effluent
Toxicity
Figure 4.1. Treatment plant optimization logic flow diagram.
wastestreams at the time of treatment plant design,
and which receive only partial treatment through the
plant. Some components of the influent may even
simply pass through the treatment system.
Therefore, when evaluating current performance
against design criteria, it is necessary to understand
possible changes in influent quality and factor them
in.
Several areas to be considered when evaluating
influents and how they might have changed since
treatment system design include:
Raw chemicals or materials used in the process;
Byproducts or reaction products produced during
the process;
Reaction vessels, valves, piping systems,
overflow points, and other mechanical aspects of
the system;
Wastestreams produced, volumes, and routing
paths; and
Non-point sources.
At this stage there may be a great deal of overlap
between this study and the chemical optimization
and good housekeeping surveys. The survey team
must be aware of this and sensitive to it. The goal at
this step is to identify, define, and understand the
various contributors to the individual wastestreams,
without conducting detailed chemical analyses.
It also should be recognized that the pollutants
causing effluent toxicity may not have been of
concern when the treatment system was designed.
Alternatively, the treatment system designer may
have been unaware of the toxic pollutants in the
influent. Possible contaminants in the raw materials
should also be considered when evaluating influents
(see Section 5).
Another consideration is variability in the flow and
loading of influent streams. Variability in the
influent may be attributed to a variety of
circumstances, including changes in processes, plant
or process start ups or shut downs, and production
rates. Any changes from design criteria must be
defined, if possible from the existing information.
Finally, the frequency at which various activities
take place at the plant must be gauged. Recurring
4-2
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activities, such as annual plant shutdowns, may have
a significant impact on operations of the treatment
facility. One would expect to find reduced loading
from normal process flows during this period.
However, unique wastes generated during the
cleaning and maintenance of various plant
components may have a significant impact on
treatment plant operations. Similarly, recurring but
non-continuous activities, such as boiler and cooling
tower blowdowns, may add toxicity to the influent
which may not be detected under some types of
surveillance.
Description of Treatment System
The description of the treatment system begins by
examination of the design documents and subsequent
modifications. The objective at this stage is to define
what types of pollutants the plant was designed to
accommodate, both qualitatively and quantitatively.
Parameters of interest include:
design basis for each constituent, including
variability in flow conditions and concentrations;
treatment sequence;
performance projections by constituents;
operational flexibility of each process; and
treatment objectives and projected effluent
standards.
Design parameters which deserve special attention
at this stage include design flow and mass loading
rates. Most plants are designed to handle specific flow
and mass loadings. These are usually based on
loading projections, performance estimates, and
permit requirements at the time the treatment
system was designed. To account for uncertainty in
production or design, factors of safety are usually
incorporated. Many times design capacities will be
exceeded in actual operations; sometimes resulting in
plant upsets or pollutant pass-through.
Understanding the actual capacity of the system is
necessary in this analysis.
A flow schematic of the present system should be
developed which indicates sources of influent waste
streams, treatment steps in the process, sequencing
of flows, losses within the treatment system,
treatment by-products and final effluent disposition.
The flow schematic should be simple, yet detailed
enough to help determine whether the system, as
designed, is being subjected to abnormal,
unanticipated, or irregular flow and loading
conditions. A tabular summary should be prepared of
design capacities of each component.
Each process within the treatment system should be
examined and its impact on the final effluent quality
estimated. This evaluation should be made with both
the actual and design considerations of the system in
mind. Specific parameters of investigation include
whether the unit is functioning according to design
parameters and its ability to reduce non-design
constituents, such as toxics. Overall plant
performance will be judged through assessment of
both operating and design information.
Available data on by-products of the treatment
process should also be examined during this phase.
Of specific interest will be solid waste (sludge) and
air emissions from the facility. Information on the
characterization of these by-products will aid in
determining whether toxics removal is taking place
in the present system. Special disposal problems
resulting from these emissions should be noted as
they may be affected either positively or negatively
by treatment process alterations.
In addition to the design parameters, the treatment
system should be evaluated as to its removal
efficiency of other "non-design" parameters. For
instance although activated sludge is typically
designed to remove BOD, many metals and non-polar
organics, potentially toxic compounds, are also
removed. Removal of non-design parameters which
may be toxic should be evaluated and the impact of
process optimization or modification on their removal
considered.
After examination of the treatment plant operations,
the analyst should be able to suggest conditions
under which the plant would operate most efficiently.
The analyst should also be able to determine, based
upon knowledge and examination of the system,
where treatment failure is likely to occur, and why.
This knowledge will guide further analysis into
actual treatment systems operations, and ways to
optimize the performance.
Analysis of Treatment System Operation
After reviewing plant loading and design
information, review of actual treatment plant
operation should begin. This is the step where the
analyst accumulates information on actual plant
operations and compares this to design, or theoretical
operations to see how well the two compare. A
tabular summary of system performance should be
prepared as a comparison to design capacity for each
component.
Two important parameters for this review are flow
and mass loading. Either over or underloading may
be found to be significant in subsequent evaluations.
Both impact plant operations and affect the quality of
effluent from the treatment works. Overloading in
the plant can lead to poor treatment due to pass-
4-3
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through of certain quantities of the constituent to be
treated. Underloading indicates either overdesign or
under-utilization of capacity. An under-utilized plant
has the capacity available to treat waste streams not
presently subject to treatment. Additionally
underloading of BOD, a dilute waste stream for
instance, may reduce treatment efficiency.
Information on plant loading is normally available
through records maintained at the treatment plant.
Plant bypassing also bears critical examination.
Plant operators are often a good source of
information, as it is often the operator's decision to
bypass flow. Frequent bypassing may be indicative of
a plant operating at or near design capacity. In
addition, bypassing may be a major source of toxicity
in the final effluent. Bypassing during and after
heavy rainfall may allow toxic components in the
runoff to be released to the receiving water without
treatment. A thorough effort should be made to
correlate bypass events with effluent toxicity.
Shock loads may be released during normal cleaning
and maintenance activities, or may occur as a result
of a spill, process upset, etc. The frequency and
impact of shock loads on the treatment plant should
be evaluated through review of plant records
(Berthovek and Fan 1986). Each occurrence will have
a unique impact on the treatment process. These may
show little or no effect on the process, may result in
collapse of the treatment performance, or may be
some middle ground. The frequency and duration of
such loadings, and the time required for complete
treatment recovery, should be determined. Again, a
thorough effort should be made to correlate shock
loading and process upsets with toxicity data.
Plant operations should be critically reviewed.
Operating procedures which differ significantly from
the original design may result in effluent quality
different than anticipated. Variations between shifts
may also show significant fluctuations in effluent
quality. Operations may have been altered, out of
necessity, due to changes in process or influent
wastestreams. Other times, plant operators may have
initiated changes out of convenience which
unintentionally impact treatment effectiveness.
These changes or alterations should be documented,
and their impact on final effluent quality assessed.
Operation and performance of the intermediate
stages in the treatment process should be as closely
scrutinized as the overall system effectiveness. For
example, toxicity reduction through a primary
clarifier, which is presumably a function of solids
removal, will continue only as long as solids are
removed on a regular or continuous basis. However, if
solids are allowed to accumulate in the clarifier,
toxicity may worsen, due to ineffective solids removal
or release of toxics into the water phase.
It is important to recognize that the quality of the
final effluent is not always attributable to influents.
Some treatment processes may result in higher
toxicities rather than lower toxicities. Some
examples of this phenomenon are the generation of
toxic biological endproducts, the addition of toxic
chemicals as treatment aids (e.g., cationic polymers),
and the production of toxic chlorinated organics
during the disinfection process. Chemistry within
each process should be examined, especially those
which are subject to chemical additions and
enhancements.
Implementation of Corrective Action
The objective of system optimization is to identify
changes in plant operations which will result in a
higher effluent quality without significant
modification of the facility (physical) or the
chemical/biological processes.
During the definition and evaluation phases, areas
which may not be operating at an optimal or design
level, and those which may be improved through
minor modification and adjustments in plant
operations will have been identified. Corrective
measures must now be defined and implemented,
such that at the completion of the process, plant
operations are as good as they can be, given present
plant makeup and operations.
One area to examine is mass and flow loading rates.
These can be adjusted by water conservation,
retention, inflow controls, and waste stream mixing.
Overloaded plants may be made to operate more
efficiently by "bleeding" certain contaminants into
the headworks of the plant. This may be possible
through taking advantage of existing system holding
capacities, or through rerouting of streams to provide
holding.
Modification of the flow sequence through the
treatment plant can sometimes significantly affect
overall treatment. If piping systems, pumps, etc. are
already in place, such that only minor redirection is
needed to effect the change, resequencing may be an
expedient means to optimize plant performance and
improve effluent quality. One example might be to
convert two tanks from parallel to series operation.
Redirection of individual flow paths may be another
way to optimize plant performance. Certain
wastestreams may be treated more effectively by
some processes than others. Similarly, the same
process may afford different levels of treatment to
various waste streams dependent upon such
conditions as loading rate, influent concentration,
retention times, and chemical feed rates. It may be
possible to improve overall effluent quality by
adjusting plant operations according to the source
and composition of the influent waste stream. An
4-4
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example of this might be segregation of the influent
stream to treat only those streams containing metals
in the precipitation process; at lower flows and higher
concentrations, metals removal will be more
efficient.
Batching or sequencing of flows may be other means
to optimize performance. At a facility with a variety
of different wastestreams, a singular plant operated
continuously may not be capable of providing the
desired level of treatment. If, however, waste streams
could be held for a scheduled strategic release and
plant operations could be adjusted to provide the best
level for the individual waste stream(s) involved,
effluent quality may be dramatically improved. This
would be particularly applicable to the handling of
peak loads or non-compatible wastestreams.
Sequencing of wastestreams would involve influent
control, such that waste from one process passes
through the treatment facility separate from wastes
from other processes. This would allow adjustments
to be made in plant operations to accommodate the
individual wastestreams involved. Batching or
sequencing may also be useful when mixing of
process waste streams may act to mitigate toxicity
(e.g., an acid and basic waste stream).
Increasing the residence time of the effluent in the
treatment process may facilitate degradation and
reduce toxicity. If excess storage space is available on
site, residence time could be increased by routing
effluents through these areas. In addition, the use of
baffles may increase residence time in areas already
allocated.
Finally, consistency of plant operation must be
maintained. Variations between shifts, over
manufacturing and production cycles, etc., must be
reduced to a minimal level. This may be extremely
difficult at some facilities with widely variable
processes and production schedules.
When possible, toxicity testing should be utilized to
determine the effect of optimization on determination
of the efficiency of toxicity reduction. Both the
influent and effluent should be tested and the
effectiveness of the various optimization activities
determined. Phase I characterization procedures can
also be used to gain additional information on the
effectiveness and result of implementation.
Optimization steps may be modeled either
mathematically or in the laboratory, prior to system
adjustments, These steps may help to streamline the
optimization process, and reduce or eliminate trial
and error activities. Additionally, if modifications are
planned for which the outcome is uncertain and
which involve some element of risk, modeling may
provide the degree of certainty needed to either
proceed with the change over, or to investigate other
alternatives.
Follow-Up and Confirmation
As with any system change, once the change has been
completed, the effect must be assessed. This will come
through follow-up and confirmation studies. Even if
changes made in plant operations have the desired
effect on effluent quality, periodic follow-up will be
required to confirm that the toxicity reduction is
maintained.
It is also important to note that changes in treatment
operation that result in a reduction of effluent
toxicity must not do so at the expense of other limited
parameters. For example, a change in treatment
operation that results in a reduction in effluent
toxicity is not necessarily desirable if it means that
the facility's TSS limit will be violated.
4-5
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Section 5
Chemical Optimization
Chemical optimization, when utilized in a TRE, is a
process which occurs simultaneously with
housekeeping and treatment plant optimization. The
initial steps of the chemical optimization process are
as follows:
Review the use of chemicals in manufacturing
process to insure that only the amounts of
chemicals needed are used.
With respect to their concentration in the final
effluent, review all available aquatic organism
toxicity data for raw materials and process
chemicals and their contaminants and by-
products (known or potential). Emphasis should
be given to data for the species, genera and/or
family of aquatic organism used to test the
toxicity of the effluent.
Review biodegradability information (aqueous)
for raw materials and process chemicals and their
contaminants and by-products (known or
potential).
Determine if less toxic/more degradable
alternatives are appropriate, and whether or not
they exist.
The goal of the chemical optimization process is to
identify simple solutions to the toxicity in the
effluent. This process is a first cut at reducing
toxicity by removing possible causative agents. In
general, no cause and effect relationship will have
been established between the chemicals being
removed or substituted and final effluent toxicity.
However, there may be some evidence these
chemicals can cause toxicity and that their removal
will help alleviate the problem at the facility. This
evidence may come from experience at other facilities
of similar type or from reported toxicity in the
technical or scientific literature. Figure 5.1 depicts
the chemical optimization flow logic. Case summary
(Appendix) A-4 provides the only true chemical
optimization step found in the case summaries
reviewed. Chemicals used in the manufacturing
processes were reviewed for potential toxic
components and chemical application techniques
were implemented to optimize chemical usage.
Similar to this case study, the investigators in case
summary A-l reviewed data on all possible raw
ingredients to determine sources of toxicity.
Information Gathering
There are two important sources of information for
the chemical optimization study. These are process
design and operating information, and MSDS. Each
provides valuable information for the conduct of the
study.
Process design and operating information will
provide a definition of unit operations,
manufacturing processes, and chemical uses and
additions. Where possible, this review should
include:
Examination of wastestreams produced by
specific production processes;
Chemicals and raw materials and their
contaminants and by-products used in the
process;
Chemicals used in treatment;
Chemicals and material use rates;
Percentage of chemical in the final product; and
Chemical reuse and waste recycling activities.
This information will be useful in defining which
processes and attendant wastestreams are most
likely to influence toxicity in the effluent. Also
during data collection activities, a comprehensive list
of MSDS should be assembled. These should be
available through the facility health and safety
coordinator, or the person alternatively responsible
for OSHA compliance.Information contained in the
MSDS will aid in the identification of probable
sources of toxicity, and will assist in defining the
chemical makeup of certain chemicals suspected of
adding toxicity to the effluent.
It is important to remember that the chemical
concentration of interest is that which is in the
5-1
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Initiate Chemical
Optimization Study
Collect
Data
Raw Material and
Chemical Process
Review
Probable
Contaminant Source
Identified
Identify Control
Strategies
No
Initiate Controls
Test Toxicity
Initiate TIE
Probable
Contaminant Source
Identified
Follow-up and
Confirmatfom
Figure 5.1. Chemical optimization flow chart.
sample tested for toxicity (i.e. the final effluent).
Influent concentrations are only of use when the
compound is treated to a level below analytical
detection but remains present at a level toxic to the
test organism (in this case the chemical's presence in
the influent acts as a marker).
Process Chemical Review
In this review the role of each chemical and the
amounts used in the industrial process are examined.
Many compounds are used in manufacturing
processes in an non-optimized manner. The reasons
for using the amounts chosen are many times based
on application, not science. Each process chemical
usage amount should be questioned and suppliers
called in to consult on the application amounts. If the
material is not in the process effluent, it cannot
contribute to the toxicity of the WWTP effluent.
The steps in the chemical process optimization
include:
Making a list of all chemicals used;
listing the quantities used (e.g. per month);
determining the pounds used per unit of
production; and
determining the pounds used per gallon of water
discharged.
For each chemical identified, the questions that must
be asked include:
What purpose does this chemical serve?
Can the amount used be reduced?
Can the chemical be reused?
Does it have to be discharged?
5-2
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At the completion of the review process, the analyst
will have developed a clear picture of how the plant
operates and how these operations may impact final
effluent toxicity.
Review MSDS Information
In this process the MSDS information is reviewed
and any aquatic toxicological information is noted.
Suppliers should be asked for the aquatic toxicity
information if the MSDS does not list it.
The steps of the MSDS review include:
Obtain an MSDS for all process chemicals
discharged.
MSDS sections providing information on aquatic
organism toxicity should be highlighted
Examine the Hazardous Ingredient section and
note the "hazardous substances" listed.
Look at the disposal section of the MSDS and note
whether or not the material is a hazardous waste.
Look at the environmental section of the MSDS
and note if any acute toxicity (e.g. LCso) data for
aquatic biota are available.
If no aquatic data are available, ask the suppl
for aquatic toxicology information.
lier
Obtain and examine biodegradability
information for each suspected compound.
Categorize all chemicals by hazard and irritation
potential and use standard references to obtain
aquatic toxicity information, if possible.
For example, if the biocide ANYCO 1111 SOME-
BIOCIDE, a cooling water treatment additive, is
noted as being used by an industry undergoing a
TRE, the MSDS for this material would be obtained
(ANYco Chemical Company) and reviewed. In this
example case, the MSDS has a section (MSDS Section
6) on Toxicological Information. All data presented in
this toxicological section of the MSDS are found to be
for humans and animals. However, further search of
the MSDS would detect the statement that the
product is toxic to fish (MSDS Section II, Spill and
Disposal Information). Then in the following section
on Environmental Information (MSDS Section 12)
actual aquatic toxicity data would be found. The data
given in this section of the MSDS for Daphnia magna
(an LC50 value of about 0.15 mg/L) and Fathead
Minnows (an LCso value of 0.12 mg/1) indicated
significant toxicity to aquatic organisms. No
biodegradation information is provided in the MSDS.
Therefore, this material would become listed as a
"suspect" causative agent and targeted for further
examination in the TRE process.
After this information is reviewed, the following
questions should be asked:
Are there any less toxic and more degradable
products available?
Can most serious problem chemicals be isolated
from the wastestream or treated prior to mixing
with the wastestream?
Were toxic chemicals used in high quantities (i.e.,
at or above known effect concentration) identified
during the Process Chemical Review?
Chemical Composition Screen of
Incoming Raw Materials
In this part of the process, the raw materials that are
used to make the final product are examined to
determine if a chemical is, or could be, removed
during the manufacturing process and enter the
wastestream, If such a chemical is found, the same
information obtained for the processing chemicals
outlined above is determined for the raw material
intermediate.
The steps in this process are not as direct as those
discussed above. This segment is highly
individualized to the industry involved.
The questions to be answered include:
Are there chemicals that are removed?
What are they?
How much is removed?
Are these chemicals degradable or toxic?
Why are these chemical(s) present?
Is it necessary to remove them?
Can less onerous alternates be found?
Oufcome of fhe Chemical Optimization
Phase
As a result of this sequential process the following
information should now be available:
1. A list of all chemicals used in processing and
manufacturing the product. Included will be the
5-3
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amounts used, why the compounds are used, and
if optimization has taken place.
2. MSDS and literature reviews (if needed) will be
on file for all process chemicals.
3. A list of all chemicals and raw material
purchased on a monthly basis and a record of
production volumes during the same time period.
This information may be valuable if a source
investigation is conducted. For example: if the
characterization/identification tests show that copper
is a toxic problem, any chemicals shown to contain
copper should be investigated as potential sources of
the toxicity.
Experience has shown that once several TREs have
been conducted on several industries of the same
Standard Industrial Classification (SIC) code, some
compounds will become "known" as problematic.
These "known" compounds can be categorized and
more accurate toxicity/biodegradability determina-
tions made. Once found toxic, the first information
the industry conducting the TRE should look for is
whether or not these compounds are used. As these
"problem" compounds are identified, letters from the
discharger to supplier asking that they be reduced or
removed from any "Tradename" products should help
eliminate some of the toxic compounds known to be
used by the industry.
Data Analysis
During the chemical optimization phase, no
sophisticated analysis need be performed. However,
later in the TRE process, it may be useful to apply
regression and cluster analysis techniques in an
attempt to correlate chemical usage, water usage,
known toxicity, and other numerical factors. This
type of detail and sophistication might be done if,
after the TRE, no other means of relating chemical
usage, flows, and other factors to toxicity exist.
Follow-Up and Confirmation
The information gathered during the chemical
optimization step in the TRE can yield a great deal of
useful data. Chemicals that should not be excluded
include those used in the manufacturing plant that
may not be used in the manufacturing process. Water
treatment compounds are an example of such a
chemical.
The significance of the Chemical Optimization
Process is that for many facilities it may represent a
useful approach for identifying the source of
potentially problematic chemicals, or assist in the
confirmation of the suspected causative agent of
effluent toxicity. Ignoring this step could result in
modification of a WWTP when a simple chemical
substitution could convert an unacceptably toxic
effluent into a non-toxic one.
5-4
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Section 6
Toxicity Identification Evaluation (TIE)
The third tier in the generalized methodology for
conducting a TRE at an industrial facility is the
toxicity identification evaluation (TIE). The overall
objective of a TIE is to identify the specific
chemical(s) responsible for effluent toxicity. In some
cases the results of this evaluation may only allow
the investigator to determine the physical/chemical
characteristics of the causative agents of effluent
toxicity. In either case, valuable information will
have been obtained for either the evaluation of
treatment methodologies or for the investigation of
the source(s) of final effluent toxicity.
In TREs where Tier II evaluations of facility
housekeeping, treatment plant optimization, or
chemical optimization have indicated potential
causes or sources of toxicity, application of the TIE
procedures will usually still be needed to provide
additional "weight of evidence" and confirmation of
these suspected causes or sources. It can be expected
that in most TREs at industrial facilities the initial
two tiers of the protocol described in this document
should take no longer than two to three months or
approximately 25-30% of the total time scheduled for
the TRE. Effluent sampling and application of the
initial Phase I TIE procedures described in this
section can in most cases be conducted concurrently
with these facility information gathering and
operations assessment steps. This will allow for more
direct confirmation of any solutions or reductions in
effluent toxicity brought about by tier II evaluations
and streamline the TRE being conducted at a given
facility.
The general strategy for performing a TIE consists of
three phases and is presented as a flow chart in
Figure 6.1. The first phase is the performance of
toxicity characterization tests which are designed to
determine the class or group of the compound or
chemical causing effluent toxicity (i.e. the toxic
chemical(s) physical/chemical characteristics). The
frequency that these characterization procedures are
performed must be based on the nature and
variability of the effluent toxicity as observed in the
results of these tests. It is highly unlikely that it will
ever be sufficient to evaluate only a single sample.
The second phase of a TIE is to perform analyses
which are designed to identify the specific toxicant(s)
in the final effluent. The number and type of
chemical analyses performed will be based on the
results of the Phase I characterization tests. The
third phase of a TIE is the confirmation of the
suspected toxicants identified in Phases I and II. In
cases where phase II identification was not
successful, Phase III confirmation of the
physical/chemical characteristics determined by the
Phase I tests should still be conducted. This is
especially important where treatability studies are to
follow the TIE and modifications to, or construction of
additional treatment facilities are determined to be
necessary based on the results of the TIE and the
treatability studies.
Toxicity identification evaluation procedures are
described in detail in Methods for Aquatic Toxicity
Identification Evaluations Phases I-III (Mount and
Anderson-Carnahan, 1988), and can be summarized
here in terms of the application of these methods for
an industrial facility TRE. It should be noted that the
case studies contained in this document were, for the
most part, conducted prior to the completion of these
TIE methods and utilize this approach to varying
degrees. As more experience is gained and further
research is completed modifications and
enhancements of these methods will be made and
documented.
Phase I- Toxicity Characterization
Procedures
The Phase I toxicity characterization procedures
involve the use of a battery of bench-top tests coupled
with toxicity tests to determine the physical/chemical
class or group of the toxic components in the effluent.
The purpose of performing these procedures is to
focus the search for the causative agents of effluent
toxicity to compounds of a known class or group. This
information greatly expedites the subsequent Phase
II toxicant identification analyses by narrowing the
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Effluent Sample
Phase I Toxicity Characterization
initial Toxicity
Baseline
pH Adjustment
Aeration
Filtration
Cl 8 Solid Phase Extraction/Elution
Oxidant Reduction
EDTA Chelation
Graduated pH
Perform Toxicity Characterization Adequate Number of Times to Consider Variability
Treatability Approach
Treatabihty
Approach or Identify
Toxicant
Identify Toxicant(s)
1
Phs
Confirmatio
i
r
jso III
f
Confirm Toxicvity
Characterization
Phase II Toxicant
Identification Analyses
J
^S Identify (
L
^x. Yes
"v. Agents of bttiuent -S" r
^'v. Toxicity ^^
Go to Source Identification
Phase III
Confirmation Procedures
Confirm
Specific Toxicants
Figure 6-1. Toxicity Identification Evaluation (TIE) strategy flow chart.
range of possible toxicants and is also useful for .the
treatability studies discussed in Section 8.
Initially, an aliquot of the whole effluent sample is
tested for the baseline toxicity. If the sample is toxic,
aliquots of the sample are run through the battery of
phase I tests which are designed to remove or render
neutral (biologically unavailable) various classes of
compounds and the corresponding toxicity of these
"treated" aliquots is measured. Presently, these
procedures use acute toxicity tests to measure the
toxicity of the effluent and the treated aliquots.
Methods which utilize chronic toxicity test endpoints
to track the toxicity of the effluent sample following
characterization tests are being developed.
Toxicity characterization procedures, and chemical
specific analyses, produce snapshots of what is
causing toxicity in a given sample. Only those toxic
chemicals which are present when the samples were
collected will be characterized or identified. This
would not pose a problem if the cause of the effluent
toxicity remains constant over time. In such a
situation, one sample, regardless of when it was
collected, would be adequate for characterization
purposes. However, if the cause of an effluent's
toxicity varies over time (or, for the purposes of
toxicity treatability studies, if the concentration of
the toxicants vary over time) the analysis of only one
sample will clearly be insufficient to account for this
variability. In such a situation, the frequency of
sampling and analysis must be designed to ensure
that all of the causes of toxicity are detected and
characterized. Therefore, it will usually be the case
that Phase I effluent characterization procedures will
need to be conducted on a number of effluent samples
to ensure that the variability in the effluent toxicity
is determined.
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Components of Variability
The toxicity of an effluent can vary both
quantitatively and qualitatively. Quantitative
variability is a measure of how the magnitude of the
toxicity changes over time (e.g., ranges from 3 to 10
toxic units). Qualitative variability is a measure of
how the underlying causes of effluent toxicity change
over time (e.g., toxicity caused by high copper
concentrations at one time and high
pentachlorophenol concentrations at another). Both
of these components of variability may be (and
frequently are) present in an effluent. Therefore, a
toxicity characterization sampling program and
subsequent treatability and/or chemical analysis
programs must be designed so that both components
of variability -the magnitude and the underlying
causes - are assessed by the evaluation.
Determining the Number and Timing of Samples
The magnitude, frequency, and type of variability in
toxicity exhibited by an effluent will determine the
number of samples which must be evaluated by the
toxicity characterization procedures. In general, the
number and timing of samples must be sufficient to
capture both the pattern of variability exhibited by
the effluent and all of the toxicants which contribute
significantly to effluent toxicity over time. There are
at least two methods for assessing the type and
pattern of variability in an effluent's toxicity.
Again, the most definitive approach is to repeat the
battery of Phase I characterization procedures a
number of times on freshly collected samples of
effluent until the type and pattern of variability is
identified. In this way the variability can be assessed
concurrently with the determination of the
physical/chemical characteristics of the effluent
toxicity. This should be a very accurate approach
because the results of the characterizations are used
as the point of comparison; if variability is observed,
it is real variability. It is necessary to repeat the
characterization procedures a sufficient number of
times to ensure that both quantitative and
qualitative variability are understood prior to
preceding to either treatability studies or Phase II
toxicant identification analyses.
A second less direct approach for estimating the type
and magnitude of the variability in final effluent
toxicity is to use the existing data on effluent toxicity
which is gathered in Tier I of this protocol. If several
species of aquatic organisms were routinely used to
test the toxicity of a given effluent the responses
recorded from a number of samples could show that
the cause of effluent toxicity changes over time. The
amount that each species' sensitivity to the effluent
changes from one sample to the next provides an
indication of the magnitude and frequency of
quantitative variability in the effluent toxicity. The
manner in which the relative sensitivities of the
various species changes over time may provide an
indication of the occurrence and frequency of
qualitative variability. If the variability in an
effluent's toxicity is totally quantitative in nature,
the magnitude of each species' response would change
over time, but all species tested should maintain the
same relative sensitivities. On the other hand, if the
species' relative sensitivities also change over time,
there is evidence for qualitative effluent variability.
The use of multiple species to assess qualitative
variability is based on the observation that different
species exhibit different sensitivities to various
toxicants in effluents. For instance, for water with
the same hardness, the fathead minnow is
considerably more sensitive to cadmium (LCso =
30.5 }ig/L) than the amphipod, Gammarus
pseudolimnaeus, (LC50 = 55.9 pg/L) (U.S. EPA.
1985b); whereas for copper the situation is reversed
with G. pseudolimnaeus (LCso 22.1 pg/L) being
more sensitive.than the fathead minnow (LCso =
115.5 ug/L) (U.S. EPA, 1985c).
It should be emphasized that this indirect approach
has several potential sources of error which could
lead to inaccurate conclusions (e.g., if data from
effluent samples with different levels of hardness are
compared). Therefore, it is recommended that the
data from the Phase I characterization tests be used
as the primary basis for determinations of effluent
variability and the relative responses of the toxicity
test species should be used with caution as secondary,
supporting evidence.
Toxicity Testing Procedures
In the performance of a toxicity identification
evaluation, it is essential to select a toxicity
monitoring tool which is sensitive enough and has
similar toxicological responses to the designated TRE
target. In general, this criterion will lead to the use of
an aquatic organism toxicity test, since the
designated target will usually be expressed as a
whole effluent toxicity permit limit. The actual
selection of the toxicity test organism for the TRE
may or may not be specified as an NPDES permit
condition or in an administrative order issued by the
regulatory authority. This factor, to a certain extent,
will drive the choice of the species and the test to be
used in the TRE. In other cases the guidance may not
be specific, and the discharger may have more
discretion in the selection of the TRE monitoring tool.
However, pertinent information may be available to
aid in the selection process. For example, if the TRE
was triggered by an effluent toxicity biomonitoring
monitoring requirement, the results should prove
valuable in identifying a sufficiently sensitive test
organism. Normally, several aquatic organisms
would be utilized in this monitoring and the most
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sensitive of these should be an adequate toxicity
indicator in the TIE.
It is important to differentiate the objectives and
requirements for toxicity testing in TIEs from those
of the overall TRE and the NPDES permit
biomonitoring requirements. Usually, the
biomonitoring requirements that trigger a TRE will
be specified as the toxicity tests to be used in the
follow-up monitoring and confirmation of the
reduction in effluent toxicity (Tier VI). These permit
biomonitoring requirements and the associated
water quality-based whole effluent toxicity limits are
derived in order to be protective of State water-
quality standards. Achievement of the desired
effluent toxicity reduction to meet the TRE objective
can only be demonstrated by utilizing these same
biomonitoring tests and specified toxicity test
endpoints (LCso or NOEL). If an effluent exhibits
both acute and chronic toxicity the TRE solution or
control method must ensure that all limits will be
met. For the purposes of TIEs certain modifications of
appropriately sensitive toxicity tests can be used in
order to achieve the objectives of the particular phase
of the TIE being conducted. However, the
investigator should never lose sight of the objective of
the TRE: to reduce toxicity to acceptable levels for the
permit biomonitoring species. Thus, there must be a
demonstrated toxicological relationship or
correlation between the permitted species and the
TIE test species.
In addition to sensitivity comparable to the toxicity
test specified for permit monitoring, other criteria in
selecting a toxicity test for the TIE should be speed
and cost. In most cases conducting characterization
procedures will require the performance of a
relatively large number of toxicity tests. For this
reason, tests species which are easily cultured and
relatively inexpensive should be considered first. If a
sensitive test species which is also convenient cannot
be found, it may be possible to modify a sensitive test
so that it becomes more rapid and less expensive.
Possible modifications for the purpose of TIEs include
the use of shorter exposure times, fewer replicates,
fewer organisms per replicate, fewer exposure
concentrations, and perhaps timed lethality
endpoints. Since modifications of this nature involve
concessions to the standard quality assurance and
quality control procedures for toxicity testing, special
care must be taken to ensure that the tests results are
not compromised and are of sufficient accuracy for
the specific purpose for which they are used in the
TIE. A more detailed discussion of this subject is
presented in the EPA Phase I Toxicity
Characterization Procedures document.
As stated previously, the procedures described in the
TIE methods manual (EPA, 1988) are only designed
to utilize acute toxicity tests. However these TIE
procedures can be used in situations where either
acute or chronic toxicity triggered the TRE. In order
for the current TIE methods to be applicable for
achieving a chronic toxicity target there must be
measurable whole effluent acute toxicity present to
enable the characterization of the toxicity and the
identification of the toxicants. Use of the more easily
performed acute test in situations where chronic
toxicity is the most limiting requires the assumption
that the acute and chronic toxicity of the effluent are
caused by the same compound. This assumption can
be validated in the Phase III confirmation step which
correlates the concentration of the toxicant
(identified in Phase II) with both the acute and
chronic toxicity measured in the same sample.
If it is not possible to utilize the current TIE methods
with acute toxicity tests, then Tier II evaluations,
Tier IV source investigations, and Tier V treatability
studies can all still be carried out using EPA
procedures for chronic toxicity testing (Horning and
Weber, 1985) to achieve the TRE objectives. In cases
where measurable acute toxicity is present and the
TIE methods are used to identify the toxicant and to
select a toxicity control method, chronic toxicity tests
would then be used in the Tier VI follow-up
monitoring and confirmation of toxicity reduction,
Another concern in the selection of a toxicity test is
the presence of qualitative variability. If the
causative agents of toxicity change over time, it may
be necessary to simultaneously use more than one
sensitive monitoring species (i.e., a sufficient number
of species to detect all of the expected toxicants). If
one species is not sufficiently sensitive to all of the
toxicants over the range at which they are present in
the effluent, then the use of an additional monitoring
species for the TIE would be indicated. While this
may be a concern in certain cases, it should be
emphasized that variability in the causative toxicant
will not always necessitate the use of several
monitoring species. As long as a single species of test
organism is sensitive to each toxicant at the
concentration range found in the effluent, that
species can be used.
Description of Characterization Methods
As previously mentioned, the objective of a toxicity
characterization procedure is to narrow down the
search for feasible treatment methods and/or
methods of analysis to identify the causative agents
of effluent toxicity. This is accomplished by dividing
an effluent into a variety of fractions and then
determining which of these fractions is toxic, or by
isolating and inactivating a specific class of
toxicants. Theoretically, there are a large number of
schemes which could be devised based on
fundamental principles of chemistry and physics to
characterize an effluent. However, the restraints
which arise due to the use of toxicity tests as
indicators of which characterization tests alter the
6-4
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toxicity complicate the development of a logical,
broadly applicable procedure. For this reason
facilities faced with conducting a TRE can benefit
from detailed guidance on the methods that can be
used for toxicity identification evaluations. While
flexibility in the design and selection of
characterization procedures is attractive it should be
recognized at the outset given a TRE that the
information needed to choose the best scheme is not
readily apparent. Therefore to avoid each facility
having to expend the time and cost to develop
methods for conducting TIEs, detailed documentation
of a characterization scheme has been prepared. This
standardized characterization procedure has proven
very useful in many TIEs conducted to date and will
be described in the following paragraphs.
Some of the case studies contained in the appendix to
this document were conducted prior to the
availability of the Phase I methods and relied on
other characterization schemes. One of these was
first developed by Walsh and Garnas (1983) and uses
a sequence of resin adsorptions and chemical
extractions to divide the effluent eventually into
classes of chemicals. This approach was a forerunner
in concept to the EPA recommended procedures.
These methods may be useful as subsequent Phase I
tests in cases where the experience of the investigator
allows for their modification for application to a
given effluent. However, for use as an initial
approach for characterization of effluent toxicity a
great deal of preliminary development of methods
and laboratory procedures would need to be
conducted by the investigator at a given facility.
In the context of this discussion, the characterization
procedures described in the Phase I document are the
most germane. In this procedure, individual aliquots
of effluent are subjected to seven physical/chemical
characterization tests. Each test is designed to
remove or neutralize a specific category of toxicants.
Following the performance of each test, any change
in effluent aliquot toxicity is determined, using
short-term, inexpensive acute toxicity tests whenever
possible. The toxicity attributable to the removed or
neutralized group of compounds is calculated by
subtracting the treated aliquot toxicity from the
baseline toxicity of the effluent. Therefore, the first
characterization test is a determination of baseline
(unmanipulated) effluent toxicity. The six remaining
characterization tests are as follows:
1. Degradation Test - to determine how much
toxicity degrades over time (also establishes
acceptable sample holding time and conditions).
2. pH Adjustment Test and Graduated pH Test - to
determine the effect of pH manipulation on
effluent toxicants and the effect on causative
agent toxicity.
3. Filtration Test - to determine toxicity associated
with filterable material or toxicants that can be
made insoluble through pH change.
4. Aeration/pH Adjustment Test - to determine
toxicity attributable to oxidizable or volatile
compounds or those compounds that can be made
volatile or oxidizable through pH change(pH
adjustment helps define the acidic, basic, and
neutral character or the oxidation state of these
toxicants).
5. Solid Phase Extraction/pH Adjustment Test - to
determine toxicity attributable to non-polar
organic and metal chelate compounds or those
compounds that can be made non-polar through
pH change (pH adjustments help define the
acidic, basic, and neutral character of these non-
polar toxicants).
6. Oxidant Reduction Test - to determine how much
toxicity is attributable to oxidants or certain
electrophiles.
7. EDTA Chelation Test - to determine how much
toxicity is attributable to certain cationic
toxicants such as heavy metals.
It should be noted that in order to accurately
characterize an effluent using the Phase I method, all
of the tests should be performed. Each test is designed
to consider a different question and rigorous
conclusions can only be formed when the complete
battery of tests is conducted. As discussed previously,
the characterization tests should be performed a
suffkient number of times to ensure that variability
in the cause of effluent toxicity is addressed. In
addition, it is recommended that the results of the
complete battery of tests be considered together when
interpreting the data. Consideration of all results,
both positive and negative, will help define the
nature of the causative agents.
Quality Assurance/Quality Control
As in all studies, it is imperative that a QA/QC
program be implemented for the toxicity
characterization procedures. Such a program must
address the performance of the chemical and physical
separations as well as the toxicity tests. Detailed
guidance of QA/QC for effluent toxicity
characterizations is presented in the EPA Phase I-III
document.
Phase // - /den f/ffco f/on of Specific
fox/can fs
The aforementioned toxicity characterization
procedures are designed to identify classes or groups
of compounds contributing to effluent toxicity. With
that information, a discharger may decide to attempt
to identify the specific toxicants in these classes. A
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successful identification will facilitate the selection
of treatment options and/or the identification of the
ultimate source(s) of toxicity.
Identification of specific toxicants has the greatest
chance for success and is the most cost-effective if it is
based on the findings of the toxicity characterization
program. Such a plan would perform only those
chemical analyses which could identify specific
toxicants of the type expected in the flagged toxic
characterization classes. For instance, if the non-
polar neutral organic fraction was identified as the
most toxic, emphasis should be placed on performing
chemical analyses on the neutral non-polar organic
compounds in the effluent. In this case, there would
be no need to spend time and money on analysis of
acidic or basic organics or for inorganics.
The number and timing of specific chemical analyses
which need be performed should be geared to the
expected qualitative variability in effluent toxicity.
Guidance should be available concerning this issue
from the results of the previous effluent monitoring
and Phase I toxicity characterization data and
results. However, it is important to recognize that the
fewer the number of samples evaluated, the higher
the uncertainty that all of the causes of toxicity have
been completely identified. The Phase II methods
document provides more detailed guidance on
available methods of analysis and interpretation of
results.
Phase III - Confirmation of
/den tlllca tions
Regardless of whether the identification of toxic
causative agents progressed to single chemicals or
stopped at classes of chemicals or
physically/chemically defined classes of compounds
to be used to determine a treatment method, it is
desirable to confirm these findings. This can be
accomplished in several ways depending upon the
specificity of the identification (Personal
Communication, L. Anderson Carnahan, April. 1987).
The EPA Phase III document addresses this issue in
detail.
If single chemicals have been identified as the cause
of final effluent toxicity, there are several approaches
to confirmation:
1. toxicological literature data, for the toxicity test
species which has been used, are available for
this chemical, a comparison can be made between
the observed concentration in the effluent and its
reported toxicity. If the effluent concentration is
at a level consistent with the effluent toxicity
based on the effect concentration, confirmation is
supported.
2. Toxicity tests can be performed with a control
water, similar to the effluent in its chemical
make-up) spiked with the same concentration of
suspect causative toxicant(s) as in the effluent
sample. If the results of the spiked control water
toxicity test approximate the effluent LCso or
NOEL, confirmation is supported.
3. Effluent samples which have been treated to
remove toxicity can be spiked with the suspected
toxicants at their original concentration in the
effluent. If the same degree of toxicity occurs at
the concentration originally found in the effluent,
confirmation is supported.
4. If a water quality parameter is known to alter the
toxicity of a suspected toxicant (e.g., pH on
pentachlorophenol), the effect of varying that
parameter on the toxicity of an effluent sample
can be evaluated. If the toxicity varies in the
expected manner, confirmation is supported.
5. A number of species can be simultaneously
exposed to the effluent and the resulting species
sensitivities ranked. If, for the same species,
literature values or results for control water
spiked with the suspect causative toxicant(s)
indicate the same ranking, confirmation is
supported.
6. As the toxicity of the effluent varies over a
number of samples, compare the concentrations
of the suspected toxicant in those samples with
toxicity test results. If a significant correlation is
observed, confirmation is supported.
7. Some chemicals produce unique and discernable
effects in aquatic organisms. If the observed
symptoms match the known effects of the
suspected toxicant (as observed in a spiked
control water toxicity test), confirmation is
supported.
8. Elimination of toxicity upon removal of the
suspect toxicant(s) from the wastestream
supports the study conclusions.
This is not an exhaustive list of possible confirmation
methods. No single method would produce conclusive
evidence and, therefore, performance of several is
advisable to provide a weight of evidence. If the TIE
is halted following Phase I characterization, to
pursue a treatability approach confirmation should
still be undertaken. This will ensure that the
treatment option selected will adequately and
consistently remedy the toxicity and will produce an
effluent of sufficient quality to meet the TRE
objective.
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Section 7
Source Identification Evaluation
The results of the toxicity identification evaluation
(TIE) should provide the clearest picture possible of
what is causing final effluent toxicity. Based on this
information, a discharger must decide how to proceed
in the TRE process. One option at this point is to
evaluate various treatment methods for the removal
of the identified toxicants from the final effluent. The
other option is to search for the source(s) of the
identified toxicants or toxicity. Source controls, such
as chemical substitution, spill control or treatment of
the source stream, may be technically and
economically more attractive than treating the final
effluent. For the purpose of this discussion, influent
streams are defined as all streams that are
tributaries to the wastewater treatment system (e.g.,
process streams, surface runoff, non-process
wastewaters). Source streams are those influent
streams which are found to be contributing to
effluent toxicity.
There are advantages and disadvantages associated
with both the treatability and source investigation
options. Proceeding to treatability studies on the
final effluent is perhaps the more direct approach and
can normally result in successful resolution of the
toxicity problem. However, the cost of this success
may be high; requiring the construction or
modification of a treatment unit with additional
operating expenses. On the other hand, identification
of the source of toxicity could result in a much more
cost-effective solution and minimize the potential for
cross-media transfer of toxic pollutants to the air or
sludge during wastewater treatment. The search for
source streams may be a difficult task in complex
facilities with highly variable production schedules
and processes. However, if the upstream search is
successful and the toxicity of the identified source
streams can be easily treated or reduced by other
source control methods, a major savings in
construction, operation, and maintenance might be
realized. It is often the case, that treatment of
smaller, more concentrated streams can be performed
more efficiently and economically than treatment of
large, relatively dilute streams (e.g., the final
effluent).
Selection between the treatability studies and source
identification options must be made on a site specific
basis. Subjects for consideration in this selection
include: the results of the TIE and facility operation
tiers of the TRE, the ease of treating the final
effluent, the number of possible source streams, the
ability to modify the associated processes or
substitute process chemicals, and the variability in
the causes of toxicity. The purpose of this section is to
present some generalized methods to conduct a source
identification evaluation. Guidance on treatability
studies is discussed in Section 8 - Toxicity Reduction
Methods.
For this section, it is assumed that if the decision is
made to search for the sources of final effluent
toxicity, the following five step approach may prove
appropriate:
1. Set a search image for upstream evaluations
based on the results of the TIE.
2. Select sampling locations on selected suspect
source streams based on the TIE results and
facility information from Tiers I and II. If obvious
suspect source streams are not evident, use the
process of elimination to systematically work
upstream and narrow down the number of
possible source streams.
3a. If the causative agents of effluent toxicity have
been identified in the TIE, use chemical specific
analyses for these compounds for tracking to
sources.
3b. Where necessary, evaluate the degradation
effects of the facility treatment plant on altering
the toxicants identified in the effluent. Modify
the search image according to the results of this
evaluation.
4a. If the TIE did not result in the identification of
the specific chemicals causing effluent toxicity
use bench scale model to simulate treatment
plant degradation and track toxicity.
4b. Where necessary characterize (Phase I of TIE)
the bench scale treated samples from suspect
source streams to provide a more detailed
comparison with the search image.
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5. If specific process streams have been clearly
identified as the sources of final effluent toxicity,
move up through the process stream to identify
toxic side- streams.
At the completion of this procedure, upstream sources
of final effluent toxicity may be identified. Source
streams will only be identified if they are sufficiently
toxic and are not detoxified by the treatment system,
or if they contain the specific toxicants found in the
final effluent or their precursors. Figure 7.1 presents
a flowchart illustrating the strategy to conduct a
source identification evaluation. This process will be
greatly simplified if a specific chemical has been
identified as a causative agent of final effluent
toxicity. If this chemical is known to be chemically
refractory to treatment, it would be possible to simply
look for this chemical in the influent streams.
However, if there is the likelihood that the causative
agent is altered in the treatment process (e.g.,
rearrangement or reaction/decomposition products),
it may be necessary to follow the scheme for
evaluating treatment degradation presented in this
section. Examples of source investigations are
presented in Appendices Al, A2, A3, A6 and A7.
These examples vary in complexity from simply
identifying the toxic source streams to the final
wastestream, to large and complex facilities where
the biodegradability of toxicity of numerous process
streams was evaluated before and after treatment
(A2 and A7).
Setting the Initial Search Image
In most cases, the results of the TIE will identify
either the specific chemicals or classes of compounds
which are causing final effluent toxicity. In addition,
the manner in which these toxicants or the
characteristics of the toxicity vary over time will also
be assessed. A review of this information should
produce an initial search image for the source
identification effort. As one moves further upstream,
it may be necessary to alter this initial search image
based on how the wastewater treatment system or
any other process may degrade or alter toxic
constituents.
Sample Collection from the Influent
Streams or Selected Process Streams
Design of a sample collection scheme for source
investigation tracking must be based on site specific
circumstances and on the information gathered in
the previously conducted Tiers of the TRE. For
chemical specific tracking it may be possible to use
collected information to determine one or more
"suspected" source streams. The sampling scheme
would then be designed to confirm which of these
suspected source streams is in fact, the source of the
identified toxicants. Where there are a large number
of influent streams, and/or it is not evident from the
available facility information which are the likely
source streams, then the sampling design should
utilize the process of elimination to work up through
the influent streams to the source of the identified
toxicants. Procedures for sample collection and
handling are described in several EPA documents
(USEPA1982,1979,1988a and 1988b).
If the TIE has not resulted in the identification of the
specific toxicants, but has successfully characterized
the physical/chemical nature of the toxicity, it will
usually be difficult to select "suspect" source streams
to streamline the source investigation. In this case it
would be most effective to design a more systematic
sampling scheme which utilizes the process of
elimination to track the toxicity up the wastewater
stream to the source (s).
The information on the variability of the toxicity
gained from the TIE and also from the facility
information Tiers of the TRE should be utilized to
assist in determining the number and timing of
samples. This information should also be useful for
deciding whether grab or composite samples should
be used. Initially, flow proportional composite
samples should be used and scheduled to coincide
with facility production schedules. Influent stream
flow data must be collected as part of the sample
collection in order to determine the relative
contributions of each influent stream sampled to the
combined wastestream and final effluent.
Chemical Specific Analyses for Tracking
to Toxicant Sources
If the TIE has successfully identified and confirmed
the causative agents of effluent toxicity, chemical
specific analyses for these compounds can be used for
the source investigation. This approach involves
utilizing the chemical analysis techniques used in
Phase II of the TIE to test for these compounds in the
samples from the influent streams, In some cases the
facility information from Tier II of the TRE may
indicate which influent streams are the likely
sources of the identified toxicants. However, it will
usually be necessary to conduct sampling and
analysis to ascertain which influent stream(s) is in
fact the source of the toxicants. Methods for chemical
analysis can be found in the Standard Methods for
the Examination of Water and Wastewater (APHA,
1985) and in American Society for Testing and
Materials (ASTM) manuals.
Prior to chemical analysis of influent stream
samples, a literature search may be conducted to
determine if the toxicant identified could be a
degradation product of the wastewater treatment
plant. Where there is clear evidence that the toxicant
is a treatment by-product, the influent samples
should be analyzed for the precursor compounds as
well as the identified toxicants. In cases where
-------
Results of Toxicity
Identification
Evaluation
Search Image for
Influent Toxicity
Sources
Sample Collection
from Influent
Streams/Selected
Process Streams
L
Chemical Specific
Investigation of
Influent Streams
Evaluate Treatment
Effects on Identified
Toxicants
Compare Against
Search Image
Identify Prime
Suspect Source
Streams
Evaluate Source
Controls/Treatability
Influent Toxicity
Tracking Using
Bench Scale
Treatment Models
Characterize
Toxicity of Influent
Streams
Do Any
Influent Streams
Match Search
Image?
No
Stop Source
Identification
Evaluation - Go to
Treatability Studies
Figure 7.1. Source identification evaluation flow chart.
chemical specific analysis is successful in locating the
source of effluent toxicity the TRE can proceed to Tier
V Toxicity Control Method Evaluation. If the source
stream cannot be located following this approach, the
results of the chemical analyses of the influents and
of the TIE should be carefully reviewed to determine
if errors or unsupported conclusions have been made.
Attention should be paid to whether the samples
collected were representative of the influent streams
and that variability in the production schedules and
effluent toxicity have been considered in the
sampling design.
If this review determines that the wastewater
treatment plant may have an effect on the toxicants
that was not apparent from the literature search it
may be necessary to evaluate the degradation effects
of the treatment plant. This evaluation would
determine how the treatment system alters the
chemicals of concern. These results would be used to
7-3
-------
modify the search image to be used for the source
investigation.
Evaluate Treatment Effects on Identified
Toxicants
Wastewater treatment systems can affect the
magnitude and composition of toxicity in the
wastewater stream in a variety of ways. Some
influent toxicants may be degraded into non-toxic
moieties, others may simply pass unaffected through
the system, and still others may be altered or
degraded into even more toxic products. In most
industrial situations, it is not possible to predict the
likely outcome, This lack of predictability is not
surprising since wastewater treatment systems are
not generally designed to treat toxicity. Most systems
are designed to treat conventional pollutants and the
fate of toxicity is incidental. Therefore, since the fate
of toxicants cannot always be predicted, in some cases
it may be necessary to empirically determine how the
treatment system at a specific facility affects toxicity.
The objective of such an evaluation is to modify the
search image formed from the TIE results to include
any alterations imposed by the treatment system.
This revised search image will then allow for a more
comprehensive analysis for the chemicals in the
various process streams that are potential sources of
final effluent toxicity. Again, in cases in which the
specific causative agents of toxicity in the final
effluent are refractory to treatment, detailed
evaluation of the role played by the treatment plant
will not be necessary.
The evaluation of how the wastewater treatment
system impacts toxicity can be addressed by
performing specific chemical analyses on both its
influent and effluent streams (e.g., Appendix Section
A2 and A7). If the toxicity in the effluent is variable,
samples should be collected in a manner which
ensures that the same slug of wastewater is being
analyzed in the influent sample and the effluent
sample. This will require consideration of transit
time through the system and collection of the effluent
sample the proper amount of time after the influent
sample was collected. Using this approach,
comparison of the influent and effluent results should
identify how the treatment system affects the
magnitude and composition of wastewater toxicity at
any particular time.
The number and timing of samples required to
adequately evaluate treatment system impacts on
toxicity will depend on the type and frequency of
variability exhibited by the effluent. If the toxicity in
the final effluent has been shown to exhibit little or
no qualitative variability over time, it might be
sufficient to perform this comparison of treatment
plant influent only twice. However, if qualitative
variability has been shown to be significant, then
samples should be analyzed a sufficient number of
times so that the fate of each of the identified
toxicants is evaluated. For example, if the toxicity in
the effluent is sometimes caused by a cations and at
other times by a neutral organic, the treatment plant
analyses should be performed at least twice when
each situation occurs. Double checking in this
analysis is recommended in order to ensure a
successful source investigation.
If the concentration of the toxicant in the influent to
the treatment plant can be shown to be greater than
or equal to the concentration observed in the final
effluent, the plant probably does not have an effect
and the SIE can proceed to chemical analysis of the
process streams. On the other hand, if the specific
compound is absent in the influent or markedly
increased in the effluent relative to the influent,
more specific analysis will be necessary to determine
the precursor or parent compounds of the effluent
toxicants. Understanding the reactions would help
form the proper search image when proceeding into
the influent streams. Where this determination
proves to be a prodigious task, the investigator may
choose to use the alternative approach described in
step 4 to track toxicity.
Use Bench Scale Model to Simulate
Treatment Plant Degradation and Track
Toxicity to Source Streams
If process streams are shown to contain the specific
toxicants found in the final effluent or contain
precursors to those toxicants, there is little question
as to their designation as sources of final effluent
toxicity. However, if process streams are only
suspected as possible sources of final effluent toxicity
because they are known to contain the appropriate
physical/chemical classes of toxicants, there still
exists some uncertainty. A major reason for this
uncertainty is the possibility that even though the
process stream contains the proper class of toxicants,
the specific chemicals in the stream may degrade or
be chemically or physically transformed as they pass
through the wastewater treatment system. Just
because a class of toxicants has the potential to either
pass through the treatment process unaltered or be
degraded into another toxic class does not mean that
the specific chemicals in any particular process
stream will follow this general scenario. Therefore, if
generic toxicity is to be used to investigate which
influent streams are the sources of final effluent
toxicity, it will usually be necessary to evaluate the
degradability of each influent stream sample prior to
testing for toxicity.
The degradability of the toxicity in a specific influent
stream can best be estimated by individually passing
that stream through the actual wastewater
treatment system and observing the outcome (e.g.,
Appendix A7). Unfortunately, this type of
experiment is not usually possible in an industrial
7-4
-------
facility because of the difficulty in segregating
streams and the lack of storage for the other sources
of wastewater. Therefore, degradability must be
estimated using physical models of the treatment
system (e.g., Appendix A2).
The first step in the use of physical models is to
determine the appropriate bench scale model of the
wastewater treatment system. If the system just
contains one unit (e.g., an activated sludge unit with
no equalization or aerated ponds) then this step is
trivial. However, if the system consists of several
units (e.g., aerated ponds, followed by activated
sludge, followed by carbon adsorption), then it is
necessary to either model all of these units or identify
which unit is the most important in toxicity control.
Such an identification effort may require sampling
along the treatment process and determining the
effect of each unit on toxicity.
The second step is to design the physical model to
mimic the unit under consideration. Possible design
criteria would include hydraulic residence time,
physical and chemical conditions (e.g., pH, DO, and
temperature), and biological composition (e.g., proper
bacterial composition and biomass).
The third step would be to validate the accuracy and
precision of the physical models predictions. Model
accuracy could be evaluated by collecting a sample of
the influent to the treatment plant and passing it
through the model. If the output of the model is the
same as the real unit, accuracy is validated. Model
precision could be evaluated by setting up several
replicates of the model and passing the same waste
stream through each or by splitting a sample and
testing each aliquot. If the outputs of all replicates
are the same, precision is validated. Since the
purpose of this approach is to assess the relative
toxicity of the influent streams to determine the
source of effluent toxicity, it is not always necessary
that the bench scale physical model exactly mimic
the quantitative effect of the treatment plant. This
concession to the accuracy and precision of the bench
scale model should not compromise the models utility
to assess the toxicity which is refractory to treatment
nor should it prevent the tracking of this refractory
toxicity to its source.
The fourth and final step would be to pass each
process stream under consideration through the
model treatment system and evaluate the
degradation in toxicity. When individual process
streams are passed through the model system, it is
important that consideration be given to whether
some predilution may be necessary. One reason for
predilution is to prevent killing the bacterial
community in the unit by exposure to a very toxic
process stream. The resident bacterial flora may not
be accustomed to such high levels of toxicity, since it
is normally exposed to this process stream only after
it has been diluted by other influent streams, A
second reason for predilution is to provide an
adequate range of nutrients to the bacterial
community. The resident bacterial flora may require
a variety of nutrients which it would normally
receive from a mixture of all influent streams.
However, if only one process stream is passed
through the model, the bacterial flora may not
receive its nutritional requirements and,
consequently, not function normally. This potential
problem can be overcome by prediluting the suspect
process stream with a small amount of the mixed
influent which normally enters the treatment unit.
This small amount of predilution will not alter the
outcome of the experiment as long as a suitable
control is used. The EPA protocol for conducting
municipal TREs (1988) provides additional
discussion on designing these tests.
At the conclusion of the degradability test each
sample would be tested for toxicity. The toxicity test
used should be the same as was utilized in the TIE.
However, it is important to emphasize that either
acute or chronic toxicity tests can be used for this
evaluation. By following the sampling scheme
described above it should be possible to identify those
influent streams which are the prime suspect sources
of final effluent toxicity. These source streams will
have been identified because they are sufficiently
toxic and their toxicity is not diluted out by other
influent streams nor degraded in the treatment
system. At this point the investigator could proceed
to Tier V of this methodology, the toxicity reduction
method evaluation. If additional information on the
toxicity of the source stream(s) is desired prior to Tier
V evaluation, additional characterization of the
toxicity of the identified source stream can be
conducted.
Characterize the Toxicity of Suspect Source
Streams
The techniques used to characterize the toxicity in
the bench scale treated influent streams should be
the same as those used to characterize the final
effluent. The characterization would begin by
determining the amount of toxicity in the bench scale
treated source stream. This must be accomplished by
using the same toxicity test organism and endpoint
selected in the effluent TIE. These evaluations should
be performed often enough to detect any variability
in the toxicity of the bench scale treated source
stream. The toxic classes of compounds that are
characterized in the samples would then be compared
against the search image to provide additional
certainty that the source streams contain the proper
classes of toxic constituents. It may be useful to
perform these characterizations often enough to
assess any source stream variability that could
correlate to variability in effluent toxicity.
7-5
-------
Further Upstream Investigations
Once a process stream has been positively identified
as a source of final effluent toxicity, it may be
desirable to move upstream through the process and
identify the specific "side streams" which are the
major contributors of toxicity (i.e., Appendix A2).
Usually this, more detailed, evaluation would only be
necessary at very large, complex facilities. The
decision to proceed in this direction should consider
the cost effectiveness and technical feasibility of
segregating and treating toxic side-streams if they
are identified. If the decision is made to proceed, a
similar strategy as was pursued to evaluate process
streams should be followed.
The first step is to identify the various side-streams
which feed into the process stream. This can usually
be accomplished by review of plant blueprints and
interviews with operations personnel. The second
step is to either analyze for specific toxicants (if they
have been identified) or determine the magnitude of
toxicity in each bench scale treated side-stream. A
toxicity evaluation should use the same monitoring
tool as used in any previous characterization efforts
and would be performed often enough to adequately
consider side-stream variability. If the side-stream
receives pretreatment before discharge into the
process stream, it is essential that pretreatment be
completed before bench scale treatment and toxicity
measurements are made. If it is not possible to obtain
a side-stream sample after pretreatment, it will be
necessary to use the bench scale model to simulate
the pretreatment units. The guidance provided in the
previous section could be followed to design, validate,
and use such a model system.
At the conclusion of this evaluation, it may be
possible to identify a very concentrated process side-
stream which is the ultimate source of final effluent
toxicity. If so, source control options might be
directed towards modification of the process,
substitution of toxic compounds, installation of
additional pretreatment methods, modifications to
existing pretreatment systems, or segregating the
side-stream from the treatment system for recycling.
7-6
-------
Section 8
Toxicity Reduction Methodologies
The ultimate goal of the TRE is to reduce toxicity in
the final effluent to levels which are not harmful to
the aquatic life of the receiving water. In some cases,
additional reduction in the effluent toxicity may be
necessary for the protection of wildlife and human
health, Initially, one looks at direct solutions to
accomplish this; housekeeping, chemicals
substitution, and treatment plant optimization as
described in Sections 3 through 5. Once these steps
are completed, if the effluent still exhibits toxicity,
then other approaches are indicated. These include:
Source reduction technologies; and
Improvement of waste treatment operations.
Methods by which these may be applied to a specific
industrial facility are discussed below. In all cases,
the evaluation of methods to remove toxicity from
wastestreams must consider the ramification of
transferring toxicants to other media. Possible
problems include the need for disposal and/or
treatment of newly contaminated material. Each of
the case studies included in Appendix A include some
discussion of identified toxicity reduction
methodologies which are specific to the identified
toxicant(
Source Reduction
Source reduction involves practices and procedures
aimed at reducing or eliminating toxic loads in the
most practical, cost-effective, and permanent manner
available. Source reduction may be accomplished
from the most upstream end of the process to the
point of influent to the treatment plant. It assumes
that a specific source can be identified, and may
involve material substitution, process modifications,
waste stream commingling, pretreatment, materials
recovery or waste recycling.
Before source reduction can be effective, those
sources contributing to effluent toxicity must be
identified. This will normally take place during the
Toxicity Identification Evaluation or Source
Identification phase of this study. Once identified,
appropriate remedial technologies for these waste
streams can then be examined.
Source reduction is not a clear-cut, step-by-step
process. The steps taken, criteria examined,
procedures followed, and technologies addressed will
be highly case specific, and dependent upon such
factors as wastestream composition, physical
constraints, and flow variability. Therefore, when
examining source reduction technologies, the analyst
must first start out by identifying those areas most
likely to be positively effected, and then identifying
the technologies and approaches which are most
likely to succeed.
Toxic components are sometimes found to be raw
material contaminants, reaction catalysts, or
additives. Sometimes even slight changes in the
materials used or specification of an alternate, higher
purity material can result in a measurable reduction
in toxicity of the effluent. Further purification of
contaminated raw materials at the plant site would
be an alternate means of accomplishing this end.
Modification of the process which generates a
particular toxic waste component has been found to
be a very practical means of toxicity reduction. These
modifications may be primarily aimed at waste
reduction, or may be aimed at process efficiency; the
end result is the same. Process modification could
also consist of materials substitutions. All of these
options will involve an intensive evaluation by
process engineering with the goal of eliminating
certain specific compounds without sacrificing
product quality or process efficiency.
Commingling of waste streams prior to treatment
may also provide for toxicity reduction in the
effluent, The effect of dilution, neutralization,
reaction, precipitation or other factors may enable
treatment or degradation of toxic components which
was not otherwise possible. Care should be taken in
combining waste streams, however, so as not to
prompt unwanted reactions.
Materials recovery operations and waste recycling
are other source reduction options. For example, a
small amount of contaminated solvent may be
8-1
-------
routinely discharged to the treatment system works,
adding to the final toxicity. If this contribution can be
diverted, and the material recovered, two benefits are
possible; toxicity in the final effluent may be reduced
and solvent may be recovered. Metals recovery from
metal plating operations is another area where waste
recovery may be feasible.
Pretreatment should also be examined as a means of
reducing toxicity in the source waste streams. Both
physical and chemical methods may be feasible,
depending upon the stream. Each identified source
stream should be examined to determine the
characteristics of the toxic component(s). Knowledge
of these characteristics will allow evaluation of
alternate means to reduce the source toxicity,
thereby reducing final effluent toxicity.
Technologies which may be applicable for source
treatment include chemical oxidation; wet air
oxidation; resin adsorption; air, steam, or gas
stripping; and membrane processes including reverse
osmosis and filtration technologies. These processes
would be applied to the source stream prior to
conventional treatment. The aim is to reduce the
levels of toxic contaminants in the source streams
which are causing the observed toxicity in the final
effluent. The actual technology employed in a
particular situation would be dependent upon factors
encountered at the site. Selection of an appropriate
technology will probably require lab, bench and pilot
scale demonstrations of the effectiveness of the
technology prior to actual start up on a production
scale.
If toxicity in the effluent can be shown to result from
a particular source contribution, and this source can
be economically reduced, then these techniques
should be examined. If, however, toxicity still
appears in the effluent which cannot be attributed to
a particular source or production process, or if source
reduction is not feasible because the source cannot be
identified, then end-of-pipe treatment alternatives
must be examined.
Wosfe Treofmenf Operations
Improvements
Plant optimization is the most direct means to
improve waste treatment operations. Plant
optimization as described in Section 4 would take
place before any plant alterations occur. If plant
operations are already at an optimal level, and
effluent quality still does not meet the desired goal,
then further treatment modifications may be
required based on the results of the TIE. Areas to be
examined include hydraulic and mass loading of the
facility, chemical feed rates, biological enhancement,
source batching or segregation, effluent polishing,
and additional treatment processes.
Hydraulic loading should be examined. It is possible
that changes in existing processes or additions of new
process lines may be causing serious disruptions in
plant operations. If hydraulic loading is considered a
problem, alterations such as source sequencing,
addition of equalization or buffer tanks, and
expansion of the treatment facility, should all be
considered.
If contaminant levels in the waste streams are high
enough, a plant can be hydraulically underloaded
and still be receiving mass loadings in excess of
design capacity. High mass loading could result in
pass-through of certain toxic contaminants, or
reduction of treatment efficiency through shock
loading and upsets of plant operations. All of these
possibilities could lead to effluent toxicity and can be
prevented through appropriate system modifications.
Adjustments and substitutions in the chemical usage
in the various treatment processes can also result in a
desirable improvement in the effluent water quality.
Again, there may be sufficient difference between
design and operating conditions that adjustments are
needed to optimize plant performance. It may also be
possible, through substitution, to remove certain
chemical species which are not removed by existing
operations, and which may be adding to the toxicity
of the final effluent. Chemicals which should be
considered include: cooling tower slimicides,
ammonia nutrients, lime, some polymers, and
oxidizing agents.
Bio-enharicement is another means to improve
toxicity reduction through a facility. Not all
organisms are equally effective at degrading
particular pollutants. If a stable community can be
established which is capable of reducing certain toxic
contaminants, additional toxicity reduction may
result. This may require seeding the system, possibly
with genetically engineered organisms, with an
attendant period of growth and acclimation prior to
operation. The effectiveness and cost of establishing a
new biological population should be carefully
investigate-d in bench or pilot-scale prior to
implementation.
Batching and sequencing of flows may be desirable in
order to even out peaks and valleys in the plant
loading profiles. This can result in a more consistent
level of treatment through the plant, and hence a
better quality effluent. This may require the
construction of additional influent holding capacity
(ponds or tanks).
-------
Influent pretreatment may be required to remove
unwanted toxic constituents. This will involve the
constructing of additional facilities upstream of the
conventional treatment process. An example of where
this may be necessary is at a facility subject to high
metals in the effluent. It may be necessary to remove
these metals prior to conventional treatment.
Effluent polishing may be an appropriate
alternative. It is often times possible to reduce
toxicants in the effluent by removing them at the end
of the pipe. Such may be the case with non-polar
organics which may be effectively removed through
activated carbon or resin adsorption.
Changing treatment processes, or adding additional
steps in the treatment process, may also be a viable
reduction technology. Addition of powdered activated
carbon to the biological treatment process can reduce
organic toxins to acceptable levels. If toxicity is
shown to be a function of suspended solids in the
effluent, then the addition of a final clarifier or filter
may be required.
Because the need for additional treatment is a
function of the wastestream involved, the
technologies discussed above must be screened for
applicability to the situation at hand. Tables 8.1
through 8.4 summarize treatment technologies for
various wastestreams. These are not meant as
comprehensive summaries for the various
technologies listed. Rather, they serve to illustrate
the variety of technologies which are available for
consideration. Further information may be obtained
by consulting the selected references contained in the
Bibliography Section of this methodology
(Campanella, et al. 1986, Carpenter, et al. 1984,
Grosse 1986, Hsu 1986, Kiestra 1986, Noyes 1981,
Petrasek 1981, Fitter 1976, Rawlings 1982, Roberts
1984, Siber 1979, Tabak 1978, Weber 1983). In
addition, two good sources of information published
yearly are the literature review issue of the Journal
of Water Pollution Control Federation, and
Proceedings of the Industrial Waste Conference
sponsored by Purdue University.
Evaluation of Alternative Reduction
Methodologies
Changes in treatment methodologies must be
carefully evaluated prior to implementation. Factors
to consider include:
cost;
performance;
complexity of solution;
Table 8.1.
Metal
Effluent Levels Achievable in Heavy Metal
Removals*
Achievable Effluent
Concentration
(me/L)
Technology
Arsenic
Barium
Cadmium
Copper
Mercury
Nickel
Selenium
Zinc
0.06
0.06
0.006
0.5
0.06
0.05
0.008
0.02-0.07
0.01-0.02
0.01-0.02
0.001-0.01
0.0005-0.005
0.001-0.005
0.12
0.06
0.1
Sulflde precipitation with
filtration
Carbon absorption
Ferric hydroxide
coprecipitation
Sulfate precipitation
Hydroxide precipitation
at pH 10 to 11
Coprecipitation with
ferric hydroxide
Sulfide precipitation
Hydroxide precipitation
Sulfide precipitation
Sulfide precipitation
Alum coprecipitation
Ferric hydroxide
coprecipitation
Ion exchange
Hydroxide precipitation
at pH 10
Sulfide precipitation
Hydroxide precipitation
atpHll
'Adapted from: Lankford, et al. 1987. Iriginal reference Patterson
1986.
ease of implementation;
expected life of modification;
flexibility of the modification; and
application to various wastestreams.
In evaluating the various alternatives available, the
relative importance that each of these considerations
carries on the final selection must be established.
This will be a site specific determination and must be
made by the plant.
Costs play an important part in the selection of an
appropriate alternative. High cost solutions will
generally be regarded less favorably than lower cost,
unless other factors outweigh them. When costs are
evaluated, care must be taken to include all real costs
associated with the alternative. These may include
design and construction, maintenance and operation,
and additional disposal costs associated with the
8-3
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Relative Biodegradability of Certain Organic
Compounds*
Compounds Generally
Resistant to Biological
Degradation
Table 8.4. Air Stripping of Selected Compounds*
Biodegradable Organic
Compoundsa
Acrylic acid
Aliphatic acids
Aliphatic alcohols (normal, iso,
secondary)
Aliphatic aldehydes
Aliphatic esters
Alkyl benzene sulfonates with
exception of propylene-based
benzaldehyde
Aromatic amines
Dichlorophenols
Ethanolamines
Glycols
Ketones
Methacrylic acid
Methyl methacrylate
Monochlorophenols
Nitriles
Phenols
Primary aliphatic amines
Styrene
Vinyl acetate
Ethers
Ethylene chlorohydrin
Isoprene
Methyl vinyl ketone
Morpholine
Oil
Polymeric compounds
Polypropylene benzene
sulfonates
Selected hydrocarbons
Aliphatics
Aromatics
Alkyl-aryl groups
Tertiary aliphatic alcohols
Tertiary aliphatic sulfonates
Trichlorophenols
a Some compounds can be degraded biologically only after
extended periods of acclimation.
* Adapted from: Lankford, et al. 1987.
Table 8.3. Activated Carbon Treatment of Selected
Compounds*
Influent Effluent
Compound (pg/1)(Hg/D % Removal
Carbon tetrachloride
Hexachloroethane
2-Chloronaphthalene
Chloroform
Hexachlorobutadiene
Hexachloro-
cyclopentadiene
Naphthalene
Tetrachloroethylene
Toluene
Aldrin
Dieldrin
Chlorodane
Endrin
Heptachlor
Heptachlor epoxide
20,450
104
18
1,430
266
1,127
529
34
2,360
84
28
217
123
40
11
560
0.2
<3
27
0.1
0.8
<3
CO.l
<3
0.1
0.2
CO. 1
0.9
0.8
CO. 1
97.3
99.8
>83
98.1
99.9
99.9
>99.4
>99.7
>99.9
99.9
99.3
>99.9
99.3
98
>99.1
Compound
Benzene
Carbon tetrachloride
(tetrachloromethane)
Chlorobenzene
1 ,1 ,1-Trichloroethane
Chloroform
(trichloromethane)
1 ,2-Dichlorobenzene
1 ,3-Dichlorobenzene
1 ,4-Dichlorobenzene
1,2-Trans-
dichloroethylene
1 ,2-Dichloropropane
Ethylbenzene
Methylene chloride
(dichloromethane)
Bromoform
(tribromomethane )
Dichlorobromomethane
Chlorodibromo-
methane
Naphthalene
Nitrobenzene
Toluene
Trichloroethylene
*Adapted from: Lankford,
Solubility
(me/1)
1,780
800
448
4,400
7,840
100
123
79
6,300
2,700
152
16,700
3,190
--
30
1,900
515
1,000
et al. 1987. Original
Observed %
Removal
90
89
97
99
99
93
95
97
84
98
99 +
99 +
92
98
97
91
28
96
98
reference
*Adapted from: Lankford, et al. 1987. Original reference
Patterson 1985.
Patterson 1985.
generation of any solid waste materials (sludges, etc.)
not presently generated.
Performance of the solution must also be examined.
Performance is judged on a number of factors,
including but not limited to:
a measurable toxicity reduction;
the effectiveness of the solution on the expected
variety of flows to the plant;
the ease with which the solution can be modified
to handle future changes in the influent process
wastestreams; and
the ability of the modified process to produce an
effluent of consistent quality (i.e., consistency in
achieving final effluent toxicity limit).
It is probable that more than one effective solution
will be identified. Ranking of effective solutions by
some pre-established selection criteria will aid in the
selection of a "best" solution.
8-4
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The complexity of the solution and the ease with
which the solution may be implemented are
important factors to consider. An easily implemented
solution is often desirable over one which requires
significant investment in time and resources, not
only because of resource savings, but also because the
reception at the plant level may be better. Complex
biological systems require more lengthy start-up and
acclimation periods. The smoother the transition
process is the more likely changes will succeed in
bringing about the desired effects.
All changes will carry with them attendant useful
lives dependent upon the type of change made and
design criteria. The useful life is associated with cost
and must also be viewed in light of possible changes
in plant production processes and regulatory
requirements.
The flexibility of the reduction methodology and its
applicability to a variety of wastestreams also bears
examination. A solution may give good results over a
short time frame, but may become obsolete through
the introduction of new processes and new
wastestreams. Process changes, plant expansions,
and the like should all be considered. Fluctuations in
the present wastestream should also be examined, as
these may effect the appropriateness of the evaluated
technology.
Selection of Reduction Methodology
After potential reduction methodologies have been
identified and evaluated, the selection process takes
place. At this point, each methodology has been
examined, and certain qualities defined (cost,
performance, flexibility). Selection requires that
these qualities be ranked according to some
established criteria, such that a "best" methodology
may be chosen from those identified as potential
solutions.
Each alternative is assigned a weighting with regard
to the criteria and ranked. Selection of the "best"
alternative may then proceed based upon the ranking
achieved.
Once the alternative is identified, confirmation
begins at the lab, bench and/or pilot scales. This is
essential, since in most instances, significant
investment in time and resources is required for
implementation. Solutions which look good on paper
may not work in actual application due to unforeseen
or unanticipated factors. It may be necessary to go
through testing on several "best" solutions before one
is identified which performs up to expectations.
Implementation of the Solution
When the "best" solution has been selected and
confirmed, the implementation process can begin.
Implementation may consist of several phases,
dependent upon the mechanism selected. If a new
treatment facility is built, then this process may
include design, construction, and start up. If the
change is procedural, then these stages may be
concept, planning, and implementation. Whatever
the method selected, the final objective is the same --
reduce toxicity in the final effluent to acceptable
levels.
Follow-Up and Confirmation
After implementation, follow up and confirmation
are essential. A solution which does not function as
planned is no solution; likewise, specific procedural
changes must be carefully implemented and
maintained if they are to continue providing the level
of effectiveness anticipated. More is said on the follow
up tier in the following chapter.
-------
Section 9
Follow-Up and Confirmation
The final phase of the TRE process, which occurs
after the control method has been selected and
implemented, is to confirm that final effluent toxicity
has been reduced to acceptable levels. This can be
accomplished by implementing an appropriate
monitoring program to measure final effluent
toxicity. The follow-up biomonitoring would also
most likely be part of a required permit monitoring
program, specified in an NPDES permit and
associated with a specific limit. In general, the
acceptable endpoint of the evaluation would be the
target that the TRE was designed to meet which also
would be the permit compliance limits for toxicity.
These limits and endpoints could be for either acute
or chronic toxicity.
Usually, the applicable conditions for follow-up
monitoring will be spelled out by the NPDES permit,
administrative order, etc. Chemical analyses for the
causative agents of effluent toxicity might also be
required in the follow-up monitoring program.
Several of the case studies found in Appendix A have
progressed to the point of implementing follow-up
and confirmation activities. In Appendix A-l, follow-
up testing indicated that acute toxicity had been
either eliminated or greatly reduced. Follow-up
monitoring in Appendix A-7 was used to confirm that
non-biodegradable organic matter was still the
source of final effluent toxicity.
Normally, the same biomonitoring test and toxicity
endpoint (LC$o or NOEL) which initially indicated
the effluent toxicity and triggered the TRE will be
used to confirm the successful reduction of effluent
toxicity. The test conditions and procedures, as well
as the number and timing of samples, will be
specified by the regulatory authority. Typically, a
period of accelerated monitoring to confirm the
toxicity reduction will be required prior to resuming
regular permit biomonitoring.
9-1
-------
Section 10
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Preservation of Water and Wastewater. U.S.
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Burks, S.L. Toxicity of Petroleum Refinery
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Noergaard, G., D. Duffy, and S. Vanderboom.
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Industrial Wastewater. Noyes Data Corporation,
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Patterson, J.W. Industrial Wastewater Treatment
Technology. 2nd Edition, Butterworth Publisher,
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Petrasek, A.C. Removal and Partitioning of the
Volatile Priority Pollutants in Conventional
Wastewater Treatment Plants - A Capsule Report.
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Petrasek, A.C., et al. Fate of Toxic Organic
Compounds in Wastewater Treatment Plants. J.
Nat. Poll. Cont. Fed., V. 55, p. 1286 (1983).
Pielou, E.G. Cluster Analyses Techniques: The
Interpretation of Ecological Data. Wiley
Interscience, New York, New York (1987).
10-1
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Fitter, P. "Determination of Biological Degradability
of Organic Substances," Water Research, 10, 231
(1976).
Rawlings, G.D. Toxicity Reduction Manual for the
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Roberts, P.V., et al. Volatization of Organic
Pollutants in Wastewater Treatment - Model
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NTIS No. PB84-158856 (1984).
SCS Engineers, A Curex Corporation. Toxicity
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Cincinnati, Ohio, February 1984.
Siber, S., and W.W. Eckenfelder. "Effluent Quality
Variation from Multicomponent Substrates in the
Activated Sludge Process." Water Research, 13, 8,
August 1979.
Tabak, H.H., and E.F.Barth. "Biodegradability of
Benzidine in Aerobic Suspended Growth
Reactors." Journal Water Pollution Control
Federation, 50,552 (1978).
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Waste Regulations and Standards, Washington,
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Regulations and Standards. Washington, D.C.
(1984a).
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Impoundments. Office of Waste Regulations and
Standards, Washington, D.C. (1984b).
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Pollutants." Federal Register 49:9016-9019
(1984c).
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(1985a).
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of Water, Washington, D. C. EPA440/5-84-032,
January 1985b.
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Water, Washington, D. C. EPA440/5-84-031,
January 1985c.
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(1986a).
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Congress on the discharge of Hazardous Wastes to
Publicly Owned Treatment Works (The Domestic
Sewage Study). Office of Water Regulations and
Standards. February 1986.
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Writer's Guide to Water Quality-Based Permitting
for Toxic Pollutants. Office of Water, Washington,
D.C. (1987a).
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Reduction Evaluation Protocol for Municipal
Waste Treatment Plants." Draft dated September
1987b.
U.S. Environmental Protection Agency. 1979.
Methods for Chemical Analysis of Water and
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Aquatic Toxicity Identification Evaluations: Phase
I - Toxicity Characterization Procedures.
September 1988.
U.S. Environmental Protection Agency. "Methods for
Aquatic Toxicity Identification Evaluations: Phase
II - Toxicity Identification Procedures." In press.
US. Environmental Protection Agency. "Methods for
Aquatic Toxicity Identification Evaluations: Phase
III - Toxicity Confirmation Procedures." In press.
Walsh, C. E., and R. L. Garnas. "Determination of
Bioactivity of Chemical Fractions of Liquid Wastes
Using Freshwater and Saltwater Algae and
Crustaceans." Environmental Science and
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NTIS No. PB86-182425/AS (1983).
10-2
-------
Appendix A
TRE Case Summaries
Introduction
Appendix A presents case studies which provide examples of TREs conducted at 10
different industrial facilities whose final effluents had been found to be toxic to aquatic
organisms. The 10 examples given represent a variety of industrial processes and
illustrate a variety of approaches to TREs using the guidelines described in this
protocol. Each case study is organized to present information in five categories:
1. Initial Data and Information Acquisition
2. Toxicity Identification Evaluation (TIE)
3. Toxicity Reduction Approaches
4. Follow-up and Confirmation
5. Problems Encountered.
As demonstrated by these case studies, there is considerable latitude within each
of the categories listed above with respect to an approach of the TRE. This illustrates
that the design of any TRE is unique and should be approached with deductive
reasoning aimed at the particular situation (however, some general principles will
apply in every case). Case studies A-5 and A-9 are more representative of the approach
to conducting a TIE that is described in this protocol than are the other less recent case
studies.
A-l
-------
Section A-1
Case History: A Multipurpose Specialty Chemical Plant (MSCP) in Virginia
Introduction
The Chemicals and Chemical Products Branch
(CCPB) of the Water Engineering Research
Laboratory (WERL) of the U.S. EPA, working with
the Battelle Columbus Division (BCD), has been
developing, testing, and refining a protocol for
conducting TREs to provide guidance for permit
writers and permittees. Developing the protocol
involves several case studies by Battelle whereby
TREs are conducted at specific industrial sites. The
results of these case studies and others will be
documented and will be used to develop the final
protocol.
U.S. EPA-WERL selected a multipurpose specialty
chemical plant in Virginia as the first site (Site No.l)
for conducting a TRE base on the recommendations of
the Virginia State Water Quality Control Board.
Historical toxicity data collected in January 1985 by
U.S. EPA indicated that the final effluent at Site No.
1 was highly toxic to D. magna (24-hr. LCgo < 1
percent effluent) and moderately toxic to fathead
minnows (24-hr. LCso = 21 percent effluent). (U.S.
EPA unpublished data). The on-site activities of the
TRE at Site No. 1 started in May 1985 and were
completed in June 1986.
Initial Data and Information Acquisition
In May, 1985, an initial visit to Site No. 1 was
conducted to interview plant personnel, tour the
facility, identify and establish sampling locations,
and also visually inspect the wastewater treatment
system and the various waste streams and unit
operations of the system and plant. Operations
reports, such as NPDES monitoring reports and a list
of chemicals utilized by the MSCP, were obtained.
During this initial work, a plant flow diagram was
developed of the unit operations and waste treatment
system at the MSCP plant (Figure AM). Amines
from Unit No. 1 [Ala = 29,000 gallons per day
(GPD)] and Unit No. 4 (Alb = 5,000 GPD) are
discharged into an aerated biological treatment tank
(evaporation = 4,000 GPD; 20 to 30 day retention)
and then into the main treatment sump (Al = 9,000
GPD). Effluents from the cooling towers (A3 =
43,000 GPD), boiler (A4 = 173,000 GPD) and
metabisulfite unit (A5 = 87,000 GPD) are also
discharged into the main treatment sump (Influent A
= 341,000 GPD). The main treatment sump serves
mainly as a pH adjustment unit. Amine effluents are
basic (pH 11 to 12) whereas the metabisulfite effluent
is acidic (pH 5). Liming is done in the main treatment
sump (1 hour) and the contact time extended to 8
hours in the aeration tank. The aeration tank
(evaporation = 3,000 GPD) also receives effluent
from the collection sump (Influent B = 180,000
GPD). The collection sump receives the effluent from
the specialty chemicals (Bl= 144,000 GPD), and
from the aerosol pesticides (B2a), research (B2b) and
laboratory (B2c) unit operations (B2 = 36,000 GPD).
Effluent from the aeration tank (518,000 GPD)
discharges to the first settling pond (total volume of
800,000) where the mean residence time is
approximately 40 hours. Once or twice a year bottom
sediment (principally CaSC>4 sludge) from this pond
is removed and placed in a small drying pond prior to
disposal at a landfill. Effluent from the first settling
pond was then discharged into the second settling
pond (total volume of 1.3 million gallons) where the
mean residence time is 60 hours, then finally to a
polishing pond (total volume of 2.4 million gallons)
where the mean residence time is approximately 110
hours before being discharged to the receiving water.
North pond also discharges into the aeration tank
and first settling pond. This was an older waste
holding pond and has an intermittent discharge.
Because of the proprietary nature of much of the
chemical production at Site No. 1, very little
information on production processes was obtained.
Toxicologists also reviewed a list provided by the
Bureau of Toxic Substances Information of the State
of Virginia, which itemized all commercial
compounds utilized at Site No. 1. Historical toxicity
data collected in January 1985 by U.S. EPA indicated
that the final effluent at MSCP was highly toxic to D.
magna (24-hr. LCso < 1 percent effluent) and
moderately toxic to fathead minnows (24-hr. LC^Q =
21 percent effluent). Because the final effluent
exhibited high acute toxicity to Duphnia but only
moderate acute toxicity to fathead minnows,
A-3
-------
No. 1
Amines
29,000 gpd 4,000 gpd
Ala
No. 4
Amines
i
\
B.OOOgpd^* -'''r
*
Distillation
30,000 £
9,000 gpdj
Cooling
Tower
Figure Al-l. Multi-purpose specialty chemical waste flow diagram.
chemicals whose toxicity was arthropod-specific were
of particular interest. The review of this list revealed
several compounds and associated synergists
packaged at Site No. 1, including, but certainly not
limited to, the insect fumigants pyrethrin, allethrin,
and dichlorvos, and the insecticide synergist,
piperonyl butoxide (PBO).
Toxicity Identification Evaluation (TIE)
Eff luent Toxicity
To confirm that the final effluent at Site No. 1
consistently exhibited acute toxicity (all toxicity
units, TUs, in this Case History are acute TUs which
are values calculated by dividing 100 by the toxicity
test LCso value) and to determine which biological
test species was most sensitive, a series of acute
toxicity tests was conducted in May and August 1985
using D. magna, fathead minnows and MicrotoxR.
The results of these toxicity tests indicated that the
final effluent samples collected in May and August
1985 were highly toxic to D. magna (LCgo = 0.09
percent effluent) but not acutely toxic to fathead
minnows (LCso> 100% effluent) or Microtox (ECso
> 100 percent effluent). These results were similar to
the January 1985 U.S. EPA data for D. magna (24-hr
LCso < 1 percent effluent).
Characterization and Fractionation - Causative
Agent Identification
After identifying D. magna as the test organism, the
next step in the TIE was to systematically isolate and
identify the causative agent(s) in the final effluent. A
fractionation of the August 1985 final effluent using
the Walsh and Garnas (1983) method, into inorganic
and organic fractions was performed and each
fraction was evaluated for acute toxicity. Although
the inorganic fraction exhibited some acute toxicity
in the initial screening test (100 percent mortality in
25 percent effluent), two subsequent tests on the
same sample with the inorganic fraction showed no
acute toxicity at the concentrations tested (100
percent survival in 50 percent effluent; therefore, the
f°r the inorganic fraction was > 50 percent or
A-4
-------
< 2 TUs after storage of one day). The toxicity
originally observed in the inorganic fraction was not
persistent.
The organic fraction of the August 1985 final effluent
sample, however, was highly toxic (LCso= 0.14
percent effluent or 714 TUs). Therefore, the organic
fraction was further separated into acid, base/neutral
and residual subfractions and each subfraction was
evaluated for acute toxicity. All three organic
subfractions exhibited acute toxicity, but the acid
subfraction (LCso = 1-64 percent or 61 TUs) and the
base/neutral subfraction (LCso =0.41 percent or 244
TUs) were significantly more toxic than levels of the
solvent, methylene chloride, added during
fractionation (LCso> 10 percent or < 10 TUs). Thus,
the acid and base/neutral subfractions were analyzed
by GC/MS in an attempt to identify potentially toxic
chemical constituents.
When the acute toxicity of the final effluent was
evaluated in terms of Toxicity Units (TUs), the final
effluent sample initially contained 1,111 TUs. The
inorganic fraction contained < 2 TUs while the
organic fraction contained 714 TUs. There was an
apparent loss of some toxicity in the fractionation
(1,111 TUs in the effluent versus 716 TUs in the
combined fractions), but it appeared that the
principal source of toxicity in this sample was organic
in nature and may have resided in the base/neutral
subfraction (244 TUs in the base/neutral subfraction
versus 61 TUs in the acid subfraction and < 10 TUs
in the residual subfraction).
The GC/MS analysis of the base/neutral subfraction
showed dichlorvos present in the final effluent at a
concentration of 10 pg/L. High levels of two amines
produced at Site No. 1, an alkyl diamine and
dicyclohexylamine, also were found along with other
organic components in this sample. Screening
toxicity tests with the two amines found in high
concentrations indicated that neither the diamine
(LCso = 6 mg/L) nor the dicyclohexylamine (LCso =
16 mg/L) alone or together could have caused the
acute toxicity observed in the August 1985 effluent
sample. However, historical toxicity data on
dichlorvos showed that it was acutely toxic to
invertebrates with an LCso of 0.07 pg/L for Daphnia
pulex, an invertebrate closely related to D. magna,
the test organism used in this TRE.
Source Investigation
Site No. 1 had an aerosol pesticide packaging
operation in which empty containers (formerly
containing pesticides including dichlorvos) were
washed and the rinse water was discharged into the
sewer and subsequently into the wastewater
treatment system through the collection sump. In
mid-November 1985, the pesticide-packaging
operation at Site No. 1 (the presumed source of the
dichlorvos) was permanently closed down and moved
off-site. Therefore, if dichlorvos (or some other
component of the packaging operation) was
responsible for the toxicity of the final effluent, then
the acute toxicity of the effluent should have
decreased in samples collected after the closure of the
packaging operation.
Following the closure of the packaging operation, the
final effluent was screened three times for acute
toxicity, once in November 1985 and twice in
January 1986. The LCso values resulting from these
tests were 0,6, 81, and 79 percent effluent with TUs of
167, 1, and 1, respectively. Compared with the
August 1985 effluent sample which contained 1,111
TUs, the three effluent samples collected after the
closure of the packaging operation were much
reduced in acute toxicity to D. magna indicating that
dichlorvos from the packaging operation may have
been principally responsible for the toxicity observed
previously.
Confirmation of Source or Agent
To confirm that the acute toxicity originally observed
in the Site No. 1 final effluent was no longer present,
a second effluent fractionation was performed on a
final effluent sample collected on February 24/25,
1986 High bisulfite concentrations were present in
the effluent sample due to poor operation of the waste
treatment system (286 to 290 mg/L SO;}2') and the
sample had to be aerated to oxidize the bisulfite and
the pH had to be readjusted to 7 before toxicity
testing. After aeration and pH adjustment, the LCso
was < 3 percent effluent (>33TUs), which was a
greater than six-fold increase in toxicity compared
with the toxicity of the unaerated effluent (LCso = 18
percent effluent or 6 TUs) (Table AM).Some of the
acute toxicity observed in the unaerated effluent
sample may have been due to the low dissolved
oxygen caused by the high concentrations of bisulfite
present in the effluent sample.
The fractionation and subsequent toxicity testing of
the February 1986 effluent sample revealed that the
organic fraction was no longer toxic with an LCso >
100 percent (95 to 100 percent survival in 100 percent
effluent fraction; effluent fractionated twice). The
inorganic fraction, however, exhibited the same toxic
behavior as the final effluent with the LCso < 3
percent for the aerated inorganic fraction an LCso of
42 percent (2 TUs) for the unaerated fraction. Some of
the acute toxicity of the unaerated inorganic fraction
may have been caused by the low dissolved oxygen in
the test solutions due to the high bisulfite
concentrations in the effluent sample (resulting from
inefficient destruction of the bisulfite in the waste
treatment process). This behavior indicated that the
aeration and/or pH adjustment treatments added
toxicity to the sample by altering the effluent
components in some as yet unknown manner. In two
A-5
-------
Table Al-l. Summary of Toxicity Data on Final Effluent Samples Collected at Site No. 1 from May 1985 to June 1986
Test Species Date Test Type LC50(% Effluent) Sample Aeration
Fathead minnows
Fathead minnows
Microtox
D. magna
D. magna
D. magna
D. magna
D. magna
D. magna
D. magna
May 1985
August 1985
August 1985
May 1985
August 1985
November 1985
January 1986
January 1986
February 1986
June 1986
24-hr, screen
48-hr, definitive
20 min. definitive
24-hr, screen
48-hr, definitive
48-hr, definitive
48-hr, definitive
48-hr, definitive
48-hr, definitive
48-hr, definitive
>50
>100
>100
>1 .0,<6.25
0.09
0.6
81
18(79)t
18(<3)t
>100
No
No
No
No
No
No
No
No (Yes)
No (Yes)
No
* EC50
t Number outside of parentheses represents the LC50 of the effluent sample before aeration; number within parentheses represents the
LCsg of the same effluent sample after aeration to remove bisulfite.
subsequent toxicity tests with the inorganic fraction,
the acute toxicity decreased (LCso values of 14 and >
50 percent), indicating that toxicity in the inorganic
fraction was not persistent.
Although the organic fraction was nontoxic, it was
further separated into acid, base/neutral, and
residual subfractions and each subfraction evaluated
for acute toxicity to confirm that organic components
were no longer responsible for the toxicity observed
in the Site No. 1 final effluent and to compare GC/MS
profiles of the base/neutral subfraction with those of
the toxic August 1985 sample. All three organic
subfractions were nontoxic (<2TUs) with LCso
values of > 100, > 100, and 80 percent for the acid,
base/neutral, and residual subfractions, respectively
confirming the elimination of toxicity in the organic
fraction. GC/MS analysis of the base/neutral
subfraction showed a much "cleaner" sample (i.e.
most of the major peaks present in the August 1985
RIG were either absent or greatly reduced in
concentration in the February 1986 GC/MS scan)
with the absence of dichlorvos and the two amines
previously observed in high quantities in the GC/MS
analysis of the August base/neutral subfraction.
The unaerated whole effluent sample collected in
February 1986 contained 6 TUs with 2 TUs in the
inorganic fraction and < 1 TUs in the organic
fraction, compared with 1,111 TUs contained in the
August 1985 final effluent sample, a 185-fold
reduction in toxicity. The acute toxicity observed in
the February 1986 sample was isolated in the
inorganic fraction whereas the toxicity in the August
1985 sample was isolated in the organic fraction.
Toxic organic component(s) were no longer present in
the final effluent, but inorganic components were
now responsible for the remaining toxicity. A part of
the acute toxicity of the final effluent and the
inorganic fractions was apparently caused by the
high bisulfite concentration which reduced the
dissolved oxygen in the test chambers and stressed
the test organisms.
To determine the relative toxicity of D. magna, the
February 1986 final effluent sample (in which no
dichlorvos was detected by GC/MS) was subsequently
spiked with dichlorvos and evaluated for acute
toxicity. The theoretical LCgo for dichlorvos in the
spiked effluent sample was 0.2 pg/L compared with
the calculated dichlorvos LCso for the August 1985
effluent sample of 0.1 pg/L. Thus, dichlorvos could
have been responsible for about one-half of the acute
toxicity observed in the August 1985 final effluent
sample when the pesticide-packaging facility was
still operating. These test results provide strong
circumstantial evidence that the pesticide-packaging
operation (dichlorvos, in particular) was, in large
part, responsible for the acute toxicity originally
observed in the final effluent at Site No. 1. This is not
to say that dichlorvos alone was responsible for the
toxicity of the effluent since other changes in the
plant operation such as a reduction in amine
production were occurring concurrently with the
closure of the packaging operation.
Toxicity Reduction Approaches
The pesticide-packaging operation at Site No. 1, the
source of the dichlorvos, was permanently closed
down and moved off-site, and this in effect provided
the method of toxicity control and reduction. Had the
packaging operation remained, the following toxicity
reduction approaches at the source would have been
examined.
A-6
-------
Treatability Evaluations
- Carbon and/or resin adsorption of effluent B2a
(Figure Al- 1).
- Hydrolytic destruction of the pesticide(s) in
effluent B2a.
- Biological removal of the causative toxicant(s) in
effluent B2a. This perhaps could have been
accomplished by routing effluent B2a through
the 20 to 30 day aerated biological treatment
tank (Al).
Other Methods Examined
- Inplant controls. Limit the volume of discharge of
B2a using recycle procedures.
- Process modifications, Alter rinsing solution and
method of cleaning so that a more effective rinse
would result, one with less volume of effluent and
with better destruction of residual pesticide(s).
Basis for Selection of Method
Not applicable to this case history.
Follow-Up and Confirmation
Effectiveness of Solution
The final sample from Site No. 1 was collected on
June 2/3, 1986, fractionated into an inorganic and
organic fraction, and the final effluent and each
fraction were evaluated for acute toxicity to D.
magna. The test results showed that neither the final
effluent nor the two effluent fraction were acutely
toxic « 2 TUs) to D. magna with LCso values > 100
percent for all three tests. The two most comparable
data sets were from August 1985 and June 1986
when the wastewater treatment plant was properly
operating. These results showed that acute toxicity
present in the organic fraction of the August 1985
sample had been eliminated resulting in a nontoxic
final effluent at Site No. 1 in June 1986.
The TRE performed at Site No. 1 succeeded in its
primary objective in isolating and identifying a
causative toxic agent and then determining if the
toxicity of the final effluent was eliminated after the
identified toxic agent was removed. The original
fractionation of the August 1985 final effluent with
subsequent toxicity testing and GC/MS analysis of
the toxic subfractions showed that dichlorvos, an
invertebrate-specific pesticide, may have been
responsible for much of the observed toxicity.
Independent of this work, the management at Site
No. 1 permanently closed down the aerosol pesticide-
packaging operation and moved it off-site. After
closure, the toxicity of the final effluent was then
monitored in the absence of any inputs from the
packaging operation. The biomonitoring results
showed that in the five final effluent samples
collected after the closure of the packaging plant, the
acute toxicity in the TUs was 167, 1, 1, 6 and 1
compared with the 1,111 TUs contained in the
August 1985 effluent sample.
Final Comments, Recommendations, and
Conclusions
A TRE was found to be a useful process to isolate,
identify, characterize, and reduce or control toxic
components in this particular industrial effluent. The
fractionation procedure as designed by Walsh and
Garnas (1983) and modified during this study for Site
No. 1, was useful in the isolation and identification of
the principal toxic component (dichlorvos) in a
specific organic fraction (i.e., the base/neutral
subfraction). Although variability in toxicity of the
final effluent at Site No. 1 occurred during the study
period, caused, in part, by an improperly operating
wastewater treatment plant, the variability resulted
in different effluent components than those
originally identified as being the cause of the
toxicity. In situations where such variability exists,
it would be useful to perform additional toxicity tests
when the wastewater treatment plant is operating
properly to confirm the results and success of the
TRE.
Problems Encountered
The wastewater treatment plant was operating
properly during the August 1985 and June 1986
sampling period, in contrast to the two sampling trips
in January and February 1986 where high bisulfite
concentrations were present in the effluent samples.
The high bisulfite concentration resulted in low
dissolved oxygen in the test solutions which stressed
the test organisms and confounded the interpretation
of the test results. The inorganic toxicity observed in
February 1986 was not persistent and may have been
related to the high bisulfite concentrations present in
the effluent because of the improperly operating
wastewater treatment plant.
References
Cooney, S.D., W.H. Clement, and R. Clark. Multi-
Purpose Specialty Chemical Plant Toxicity
Reduction Evaluation (TRE) Site No.l .U.S.
Environmental Protection Agency, Cincinnati, OH
May 1987.
Peltier, W.H., and C.I. Weber (eds.). Methods for
Measuring the Acute Toxicity of Effluent to
Freshwater and Marine Organisms. EPA-600/4-85-
013, 3rd ed., U.S. Environmental Protection
A-1;
-------
Agency, Environmental Monitoring and support
Laboratory, Cincinnati, OH (1985).
U S. Environmental Protection Agency. Methods for
Organic Analysis of Municipal and Industrial
Wastewater. EPA-600/4-82-057, Environmental
Monitoring and Support Laboratory, Cincinnati,
OH (1982).
U S. Environmental Protection Agency.
"Development of Water Quality-Based Permit
Limitations for Toxic Pollutants, National Policy."
Federal Register, Vol. 49, No. 48, pp. 9016-9019
(1984).
U.S. Environmental Protection Agency. Technical
Support Document for Water Quality-Based Toxics
Control. U.S. Environmental Protection Agency,
Office of Water, Washington, B.C. (1985).
Wall, T.M., and R.W. Hanmer. "Biological Testing to
Control Toxic Water Pollutants." JWPCF,59( 1):7-
12 (1987).
Walsh, C.E., and R.L. Garnas. "Betermination of
Bioactivity of Chemical Fractions of Liquid Wastes
Using Freshwater and Saltwater Algae and
Crustaceans." Environmental Science and
Technology, 17:180-182 (1983).
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Section A-2
Case History: Tosco Corporation's Avon Refinery, Martinez, California
Initial Data and Information Acquisition
At the beginning of the study, facility-specific
information was obtained regarding the type of
facility, regulatory target limits, the design of the
existing wastewater treatment system, and existing
chemical and toxicological monitoring data for final
and internal effluent streams. As an introduction to
this case study, the following information is provided.
The Tosco Corporation's Avon Refinery produces
refined petroleum products, primarily gasoline and
diesel fuel, from domestic crude oils. During the time
EA Engineering, Science, and Technology, Inc.
conducted this TRE, the Avon refinery had an
average crude throughput of 103,100 barrels per day
and generated an average of 3.1 million gallons per
day (mgd) of process wastes, cooling tower blow down,
sanitary wastes, stormwater runoff, and other wastes
from a sulfuric acid plant which is also operated on
the site. These wastewaters were treated by the
refinery's wastewater treatment system and then
discharged into Suisun Bay through a deep-water
diffuser which provides at least 10:1 nearfield
dilution.
When the project was begun, the regulatory target for
the TRE was an end-of-pipe 96-hour LCso value of
2:50 percent effluent for the three-spine stickleback.
In August 1986, this limit became more stringent
(96-hour LC5o S 100 percent effluent).
The refinery's wastewater collection network is
served by four sewer systems: the oily sewers, the
chemical sewers, the sanitary sewers, and the clean
sewers. The oily sewer system conveys oily process
waters from all process areas of the refinery to the
API Separator/Dissolved Air Flotation (DAE) Unit.
The DAE Unit discharges to the primary canal. The
chemical sewer system carries foul water stripper
bottoms to near the head of the primary canal where
it is joined with the sanitary sewer system and the
acidic effluent from the chemical plant. This
combined stream is commingled with the effluent
from the DAE in the primary canal. The effluent from
the ammonia recovery unit also enters the head of the
primary canal in the same vicinity via a dedicated,
above-ground pipeline. These combined streams
constitute the feed water for the refinery's
wastewater treatment plant.
The wastewater treatment system and its major
influent process streams are diagrammed in Figure
A2-1. After the two aeration ponds, wastewater is
pumped to the 12 RBCs which are situated in four
parallel trains of three units in series. Flow is
normally split equally among all four trains.
Chemical feed facilities exist for feeding powdered
activated carbon (PAG) for adsorption of toxicants.
Ferric chloride (FeCIs) and polymer are injected as
flocculent aids to enhance settling in the downstream
clarifiers.
Flow from the RBCs is split and sent to two 75-ft-
diameter clarifiers for solids removal by
sedimentation. Clarified water is sent to a
multimedia filter for final removal of colloidal and
particulate matter prior to discharge to the clean
canal. In the clean canal, the treated water joins the
effluent from the clean sewer system for discharge
via a deep-water diffuser.
Toxicity Identification Evaluation (TIE)
The TIE for this program consisted of four elements:
- Selection of a cost effective toxicity monitoring
tool, and routine screening of the final effluent,
- Chemical fractionation studies to identify classes
of toxic constituents in the final effluent,
- Specific chemical analyses to identify specific
toxic elements and/or compounds in the final
effluent, and
- A source investigation study to identify the
ultimate source(s) of toxicity within the facility.
Each of these TIE components is discussed below.
Selection of a Monitoring Tool
As a first step, three commonly measured chemical
parameters (i.e., COD, BOD, and TOG) were
A-9
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ARU
FWS
#1 Aerated Pond #2 Aerated Pond
Primary Canal
d Pond
L
Rotating
Rinlnniral
Clarifiers
Contactors
(RBC)
and
Multimedia
Filter
DAF
Clean
Canal
APE
Indicates sampling locations for toxicity evaluations
Compliance
Point
E-001
(DLW)
Diffussion
Line
Figure A2-1. Conceptual diagram of Tosco's wastewater treatment system with designation of sites sampled during various
elements of this study. In this figure, the four process streams which enter the primary canal are the effluent
from the foul water strippers (FWS), Ammonia Recovery Unit (ARU), the Dissolved air flotation Unit (OAF), and
the Acid Plant Effluent (APE).
evaluated as cost-effective surrogates for the fish
bioassay using an existing facility-specific database.
However, correlation coefficients were low, ranging
from -0.04 to -0.27, which eliminated consideration of
these parameters as viable surrogate indicators of
fish toxicity.
Next, the use of a short-term biological monitoring
system (i.e., Microtox) was evaluated. Although this
test system yields quantitative results in
approximately one hour, and has been shown to
respond in a sensitive manner to refinery effluents, it
was deemed necessary to clearly demonstrate that
the Microtox system would yield results which were
similar to the three-spine stickleback test. This
correlation, obtained by performing side-by-side
Microtox and stickleback bioassays on a number of
waste stream samples, indicated that the Microtox
bioassay test serves as an adequate screening tool for
determining the relative toxicities of process and
treatment waste streams from this facility. Although
the Microtox test endpoint (20-minute ECso) was not
an exact predictor of the fish bioassay endpoint (96-
hour LCso), it was felt that Microtox was adequate for
cost-effectively screening effluent toxicity for the
following reasons:
In all cases tested, if toxicity was identified by the
fish bioassay, the Microtox also identified
toxicity.
Microtox always indicated at least as much
toxicity as the fish bioassay, and often more--
eliminating the possibility of a false negative
result.
Based on the results of the aforementioned
evaluation, Microtox was selected for characterizing
A-10
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the magnitude and variability of final effluent
toxicity. This was accomplished by analyzing 24-hour
composite final effluent samples 34 times over a 4-
month period (April-August 1985). A statistical
evaluation of the results indicated a mean toxicity (as
a 20-minute Microtox ECso) of 29.0 percent effluent
with an associated standard deviation of 11.7 percent.
During the monitoring period, the maximum and
minimum £50 values were 100 percent and 1.1
percent effluent, respectively. These Microtox 20-
minute ECso results can be expressed in terms of
three-spine stickleback 96"hourLC5o results by
using an adjustment factor that is based on the
correlation study discussed above. Based on this
relationship, the Avon Refinery effluent was
estimated to have a mean 96-hour stickleback LCso of
59 percent effluent with a standard deviation of 30
percent effluent. This extrapolated toxicity value was
sufficient to pass the old effluent toxicity limit (LCso
= 50 percent), but was considerably below the
revised limit (LCso = 100 percent) which became
applicable in August 1986.
Chemical Fractionation
In order to provide more information about the final
effluent, a fractionation procedure (Walsh and
Garnas 1983) was implemented in an attempt to
identify the number and types of chemical classes
responsible for final effluent toxicity. In this
procedure the effluent was separated into organic and
inorganic fractions and each tested for toxicity. If the
organic fraction proved toxic, it was further
separated into neutral, base, and acid fractions and
each of these was tested for toxicity. If the inorganic
fraction proved toxic, it was separated into cationic
and anionic fractions and each of these tested for
toxicity.
The specifics of the fractionation procedure are as
follows. On a weekly basis, from 3 June to 12 August
1985, composite samples of final effluent were
collected. Each whole effluent sample was analyzed
for toxicity via Microtox and then 50 ml was passed
through a 10-ml column packed with 5 ml of XAD-4
polystyrene resin. The water elutriate, which
contained the inorganic chemicals in the wastewater
sample, was then analyzed for toxicity via Microtox.
The XAD-4 column was then eluted with 10 ml of
acetone. The acetone elutriate, which contained the
organic chemicals in the wastewater sample, was
evaporated to less than 0.5 ml on a hot water bath,
resuspended in 50 ml of distilled water, and analyzed
for toxicity via Microtox.
If the inorganic fraction exhibited toxicity, it was
further separated using anionic (l-x8) and cationic
(50w-x8) exchange resins. The resulting subfractions
were assayed for toxicity via Microtox, indicating
whether anions and/or cations were responsible for
inorganic toxicity. If the organic fraction exhibited
toxicity, it was sequentially extracted with a mixture
of methylene chloride and water under basic and
acidic conditions. The resulting subfractions were
assayed for toxicity via Microtox, indicating whether
neutral, basic, and/or acidic compounds were
responsible for organic toxicity.
The results of this fractionation effort indicated that
final effluent toxicity was almost always (11 out of 12
times) attributable to organic constituents. In
addition, the most lexicologically active organics
appeared to be the neutral and, to a lesser extent, the
acidic classes. During this June-August sampling
period, the refinery and the wastewater treatment
system were operating normally and the toxicity
observed was expected to be typical.
Single Chemical Analyses
Two approaches were used in an attempt to identify
specific chemicals which might be responsible for
final effluent toxicity. The first was a comparison of
GC/MS results with maximum no-observable effect
levels (NOELs) reported in the toxicological
literature. The second was a computerized file of
routine effluent monitoring data collected over the
years by refinery personnel. These data were
analyzed for significant positive correlations between
toxicity and any of the commonly measured chemical
parameters.
GC/MS Data
As described above, the fractionation process
indicated that final effluent toxicity was routinely
associated with the organic fraction. Therefore, on
three occasions final effluent samples were analyzed
for volatile and semivolatile organic compounds
using U.S. EPA Methods 624 and 625. These analyses
were designed to identify all priority pollutants as
well as any major non-priority pollutant organic
compounds which were detected and could be
identified with the data system used for quantitation.
Through the three analyses, a number of organic
compounds were identified in the final effluent
(E001) samples. There was considerable variability
between samples with regard to which compounds
were identified and their concentrations. No organic
compounds were identified in the March sample; 10
organic compounds were quantified in the April
sample (ranging in concentration from 2 pg/L for
toluene to 120 pg/L for 2,3,4-trimethyl-3-
cyclopenten-1-one); and six organic compounds were
quantified in the December sample (ranging from 9
pg/L dibenzofuran to 130 pg/L for 2-cyclopenten-1-
one, 3 methyl).
A comparison of these concentrations with values
reported in the toxicological literature failed to
A-ll
-------
identify any of the detected constituents as the
probable cause of final effluent toxicity. For several of
these compounds (e.g., most of the ketones), virtually
no data could be found concerning their aquatic
toxicities. For those compounds for which significant
toxicological data do exist (e.g., isophorone, acetone,
toluene) the measured concentrations were well
below known effect concentrations.
Whole-Effluent Toxicity
The Microtox data indicate that the overall reduction
in toxicity from the inlet to the #1 aerated pond to
the final effluent compliance point was
approximately 83 percent. Of this total,
approximately 90 percent of it occurs in the aerated
ponds, 7 percent in the RBCs, and 3 percent in the
clean canal (Figure A2-1).
Routine Monitoring Data
Tosco maintains a computerized database of the
results of analyses performed on process and
wastewater streams. Included in this database are
chemical, physical, and toxicological properties of the
final effluent. Consequently, it was possible to
directly compare concentrations of several chemical
constituents found in the final effluent with the
corresponding fish toxicity results and evaluate for
positive correlations. Included in this evaluation
were pH, TSS, phenols, ammonia, oil and grease,
chromium, zinc, sulfur, chlorine, DO, temperature,
and flow. Review of these results indicated no
significant correlations between final effluent
toxicity and any of the chemical and physical
parameters considered. Correlation coefficients
ranged from -0.31 for TSS to 0.20 for pH.
Source Investigation Study for Toxicity
The source investigation study was designed to
identify the proximal and ultimate source (s) of final
effluent toxicity. Through a combination of sampling
and experimental manipulation, two issues were
addressed:
1. What role does the wastewater treatment system
play in final effluent toxicity--does it reduce,
increase, or alter the toxicity of influent process
streams? and
2. Which process streams are the ultimate sources
of final effluent toxicity?
Both issues are discussed below.
Toxicity Reduction Through the Existing
Treatment System
At five locations (Figure A2-1) along the treatment
process, samples were analyzed for total toxicity,
fractionated chemical class toxicity, and specific
chemical composition. These results were
synthesized to indicate how well the treatment
system functions and how it alters toxic constituents
during each stage of treatment.
Chemical Class Toxicity
Samples from each of the five sampling points were
fractionated to examine the chemical characteristics
of the toxicity. The results indicated that toxicity
reduction involved the differential elimination of
various classes of toxic constituents. The influent to
the #1 aerated pond was quite toxic, with inorganic
constituents making the greatest constitution. The
generally lower toxicity of the organic fraction was
apparently due about equally to neutral and acidic
compounds.
After passing through the aerated ponds, the
approximately 75 percent reduction in toxicity was
generally associated with the total loss of the toxic
inorganic fraction and a moderate decrease in
organic toxicity. Transit through the RBCs and down
the clean canal resulted in minimal toxicity
reduction due to the removal of some organic
constituents (principally acidic compounds).
Process Stream Evaluation
By monitoring the toxicity of major process streams
influent to the treatment system and experimentally
determining the degradability of each process
stream's toxicity, the ultimate sources of toxicity
were investigated. The following four major process
streams are influent to the wastewater treatment
system:
- Ammonia recovery unit effluent (ARU)
- Foul water strippers bottoms (FWS)
- Dissolved air flotation effluent (DAF)
- Acid Plant effluent (APE)
Each process stream was analyzed for whole stream
toxicity, fractionated chemical class toxicity, and
individual chemical composition. Degradation
studies were performed using bench-top models of the
treatment system and evaluating the reduction in
toxicity experienced by individual process streams.
Synthesis of these two sets of results identified which
process streams were the ultimate source of the toxic
constituents which were found in the effluent from
the wastewater treatment system.
A-12
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Acute Toxicity Monitoring
From the resulting data, it was apparent that the
wastewater from the ammonia recovery unit (ARU)
and foul water strippers (FWS) were the most toxic
(172 and 83 acute toxicity units (TUs), respectively).
These streams make up approximately 14 and 24
percent, respectively, of the total wastewater flow
entering the #1 aerated pond. On the other hand, the
effluent from the dissolved air flotation unit (8.8
TUs) which contributes 62 percent of the total flow,
was considerably less toxic. The acid plant effluent
was nontoxic.
Chemical Class Toxicity
By fractionating 24-hour composite samples, it was
determined that the toxicity in both the ARU and
FWS wastewaters was due to a combination of
organic and inorganic constituents. In addition, the
relative contribution made by each group was highly
variable. When inorganic toxicity was present, it was
primarily anionic in nature and organic toxicity was
due to a mixture of neutral and acidic compounds.
The toxicity in the DAF wastewater, on the other
hand, had no inorganic component and was due
almost exclusively to neutral and acidic organic
compounds.
Specific chemical analyses of the process streams
were limited to the identification of toxic organic
constituents. In general, the data were fairly
consistent with the fractionation results. The DAF
effluent contains mostly neutral organics, some
acidics, and no basic compounds. The FWS effluent
showed a somewhat different pattern with much
higher concentrations of acidic organics, considerably
lower concentrations of neutrals, and again no basics.
The ARU, on the other hand, was much different
from either of the other two processes streams in that
high concentrations of phenols were found along with
substantial concentrations of amines. Neutral
organics were not prevalent in the ARU effluent.
Biodegradability of Process Stream Toxicity
This study element was designed to address the issue
of the degradability of the toxicity of each process
stream as it passes through the treatment system.
Due to operational constraints, this issue could not be
evaluated directly because the system could not be
manipulated to receive only one process stream at a
time. Therefore, it was necessary to use bench-top
models (i.e., microcosms) as surrogates for the
treatment system and predict actual process stream
degradability from the model results.
The results of the microcosm degradability tests
indicated that the toxicity in the three major process
streams was readily (and approximately equally)
degradable. There was some loss of biodegradability
when high (>50 percent) concentrations of a
particular process stream were used. However, except
for the DAF, this was of no concern since these
elevated concentrations did not occur in the
wastewater treatment system.
Toxicity Reduction Approaches
The results of the final effluents and process stream
characterization indicated that neutral organic
chemicals were the primary cause of toxicity and that
their ultimate source(s) were probably the
wastewaters produced in the ammonia recovery unit
(ARU) and foul water strippers (FWS). Therefore,
various treatment options were considered which
might be successful at removing neutral organics
from either the final effluent or the ARU and FWS
process streams. To date, this study at the Avon
Refinery has only partially gone through the toxicity
reduction feasibility phase. Several treatment
options are currently under consideration by Tosco
Corporation. Included among these are the use of
activated carbon and increased residence time in
surface impoundments. In-depth evaluations are
planned for all promising options to assess their
chances for success from the technical, economic, and
regulatory perspectives. Tosco Corporation is still in
the early phases of these evaluations and the data are
insufficient to allow selection of a final treatment
option.
Bench-top feasibility-level studies were performed to
ascertain whether one option, activated carbon, could
reduce toxicity in the final effluent and the ARU
process stream to levels which would ensure
compliance with the mandated effluent toxicity limit.
This was accomplished by the performance of batch
experiments using seven different brands of
activated carbon and analyzing the treated effluents
via Microtox.
The results obtained from these batch equilibrium
studies indicated that all six carbons tested could
effectively treat the final effluent to the acute toxicity
criterion level. However, the concentration of carbon
required varied considerably between brands
(between 100 and 700 ppm).
Similarly, all seven carbons tested could effectively
treat the ARU process stream such that the final
effluent will be in compliance. As before, the
concentration of carbon required to meet this
criterion varied considerably between brands
(between 1,000 and 2,000 ppm). Based on the
experiences gained during this project, the following
insights concerning the evaluation of treatment
options are made:
1. Technical feasibility can be screened at the bench
scale level, but can only be verified through pilot
A-13
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through pilot scale plants operating under actual
field conditions.
2. Economic evaluations must consider both the
capital and operating costs of the project, with
special emphasis on future trends in the
availability and cost of disposal for any waste
generated.
3. The evaluation of a treatment option must
consider its capacity to cost-effectively meet
potentially more stringent regulations.
4. Caution must be exercised when solving a water
quality toxicity problem by transferring it to
another medium (e.g., solid waste as with
carbon). Environmental concerns are likely to
diminish or eliminate the attractiveness of such a
solution over time.
These items are not intended as a definitive list of
concerns which must be addressed in evaluating
treatment options. However, they should provide a
starting point for the design of the evaluation
program.
Follow-Up and Confirmation
As stated above, a final toxicity reduction solution
has not been selected although preliminary bench
scale testing has indicated that activated carbon will
reduce final effluent toxicity to acceptable levels.
Problems Encountered
During this study, a number of methods and
techniques were used in the course of identifying the
causes and sources of toxicity. Some of these (e.g., the
use of microcosms in degradation studies) were
primarily research tools adapted to a real world
situation. These did not have standard protocols and
required some innovation in their design and
interpretation. Planned process unit turnarounds,
and unplanned upsets occurred occasionally,
resulting in abnormal effluent quality. These events
provided insight into possible effluent variability,
but at the same time made performance of planned
evaluations difficult.
References
EA Engineering, Science, and Technology, Inc.
Toxicity Reduction. Evaluation at the Tosco
Corporation Avon Refinery, Martinez, California.
Summary prepared for U.S. Environmental
Protection Agency Office of Water Enforcement
and Permits, Washington (1987).
Fluor Daniels and EA Engineering, Science, and
Technology, Inc. Tosco Avon Refinery - Wastewater
Treating Studies. Prepared for Tosco Corporation,
Martinez, California (1987).
Walsh, G.E., and R.L Garnas. "Determination of
Bioavailability of Chemical Fractions of Liquid
Wastes Using Freshwater and Saltwater Algae
and Crustaceans." Environ. Sci. Technol., 17:180-
182 (1983).
A-14
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Section A-3
Case History: Martinez Manufacturing Complex, Shell Oil Company
Introduction
The California Regional Water Quality Control
Board (CRWQCB) regulates the quality of effluent
discharged from Shell Oil Company's refinery in
Martinez, California, via an NPDES permit. Since
the early 1970's the facility's whole effluent acute
toxicity limit has become more stringent, increasing
from a static acute LCso value of > 40 percent
effluent, to a newly revised limit (effective 20 August
1986) which required LCso values > 100 percent
effluent based on flow-through acute testing using
the three-spine stickleback (G'aster-osteitis aculeatus).
In the early 1970s, extensive chemical and
toxicological research was conducted by Shell to
investigate the facility's effluent. Supplemental
studies (conducted in 1976 and 1980) (Hanson 1976,
1980) examined the causes of the observed whole
effluent toxicity. Constituents implicated in these
studies included oil and grease, polymers and
ammonia.
The information presented in this case study is the
result of the above requirement and is derived from
several research efforts conducted from 1976 to 1985.
These studies resulted in specific recommendations
for the plant which included improved treatment
system operation, changes in the polymer addition,
and more aggressive in-plant source controls.
Initial Data and Information Acquisition
Plant Description
Shell Oil Company's Martinez Manufacturing
Complex (MMC) produces refined petroleum
products, primarily gasoline, diesel fuel, lube oils,
and greases. As with many large industrial
complexes, plant operations may vary over time.
Process wastes are treated in a central wastewater
treatment facility which includes oil/water
separation, biological oxidation, secondary
clarification, and tertiary nitration. MMC discharges
through a single deep water diffuser into an
estuarine environment at a rate of approximately 4
million gallons per day (MOD).
Toxicity Identification Evaluation (TIE)
Characterization and Fractionation
To meet anticipated toxicity limits, a program was
initiated to investigate the toxicants present in the
final effluent. Based on plant operations experience,
ammonia and oil and grease were among the
potential candidates. Therefore, an investigative
procedure was developed to determine if these (or
other chemicals) were the primary toxic agents.
In 1976, effluent was obtained from a point just prior
to discharge for use in the analyses. The
fractionation/characterization procedure involved
freon extraction of acidified wastewater to remove oil
and grease, followed by nitrogen stripping at alkaline
pH to remove ammonia. Oil and grease and ammonia
were also added back to the "stripped" sample to
determine if these components were the only toxic
agents removed during the extraction and stripping
procedures.
Toxicity tests and chemical analysis for a specific
group of parameters were conducted on the complete
effluent and at each stage of the extraction process.
However, after collecting and analyzing four
samples, the unadulterated whole effluent
apparently became (acutely) nontoxic and the testing
program was suspended. Analysis of the collected
data revealed some information. The toxicity of the
effluent decreased after the removal of the oil and
grease fraction and toxicity increased after the oil
and grease was added back in. However, there were
not enough data to make a precise estimation of the
toxicity of the oil and grease fraction. Analysis of the
oil and grease extract using infrared and ultraviolet
absorbance procedures indicated the presence of
naphthenic acid compounds with minor amounts of
amines and aromatic hydrocarbons. The simplest
naphthenic acid (cyclohexane carboxylic acid) is also
reported to be toxic at concentrations of 5-7 mg/L,
levels approaching those observed in the wastewater.
The major source of naphthenic acids in MMC
wastewater was identified as the wash water used
during crude oil desalting. Naphthenic acid was
A-15
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shown to be most toxic at low pH (Shell Oil Company
1986).
acutely toxic biotreater effluent and spiking with the
component of interest.
Ammonia levels were consistently low because of
nitrification in the biological treatment system
during the earlier studies, and this was believed to be
one of the major reasons why the effluent remained
essentially non-acutely toxic.
Recognizing that the acute toxicity of the waste
discharge had for all practical purposes disappeared,
a program was initiated to investigate what caused
the disappearance. Daily toxicity tests were begun on
final effluent, and various refinery processes and in-
plant waste streams were monitored to identify
relationships between toxicity and potential sources
of toxic wastes whenever the waste stream exhibited
acute toxicity. In addition to daily acute toxicity
tests, various waste streams were monitored for
ammonia, nitrate and nitrite nitrogen, organic
nitrogen, TSS, oil and grease, COD, and TOC.
Of the 37 different manufacturing processes, there
appeared to be a strong cause/effect relationship
between the chemical manufacturing process which
produces diallylamine (DAAM plant), concentrations
of ammonia in the effluent, and effluent toxicity.
Amine compounds identified in the effluent were
ethylenediamine, monoallylamine, diallylamine,
triallylamine, dimethylaminopropylamine, and
polyethyleneimine, a polymer used during the
flocculation phase of waste treatment. It was not
clear how amines reacted during effluent treatment
to cause toxicity and there is some evidence that: (1)
amines may be converted to ammonia during
biotreatment; (2) some amines may pass through
biotreatment at high concentrations which may be
toxic; and (3) amines may inhibit nitrification of
ammonia. All three methods of actions are possible
depending on circumstances.
A third study (Shell Oil Company 1986) was
conducted in 1984 and 1985 to identify the sources of
toxicity in the biotreater effluent. Through the
review of the above studies, naphthenic acids,
ammonia, vanadium, and a polyethyleneimine
polymer used for coagulation in the secondary
dissolved air flotation clarifier were selected as the
most significant contributors to effluent toxicity for
which dose-response data should be developed.
Although earlier studies identified organic nitrogen
compounds (amines) as potential sources of toxicity,
control measures implemented between 1976 and
1979 sufficiently reduced concentrations of amines in
the final effluent.
The objective of this study was to determine a dose-
response relationship for each constituent in the
effluent. Toxicity tests were performed using non-
For oil and grease, the residue was toxic to fish when
added to a non-toxic effluent at a concentration of 12
to 25 mg/L. Because the oil and grease fraction was
observed to consist primarily of naphthenic acids,
toxicity tests were also performed using refined
naphthenic acid and showed a 96-hour LCso in the
range of 5 mg/L which is consistent with published
data. However, it is difficult to relate the toxicity of
naphthenic acids to oil and grease because of the
complex nature of oil and grease.
The acute threshold effect concentration
(concentration in the effluent which results in an
LCso < 100% effluent) for ammonia in the Martinez
Refinery biotreater effluent was between 0.9 and 1.0
mg-N/L un-ionized ammonia. Within the pH range of
the biotreater effluent, the acutely toxic threshold
concentration was expected to be above 20 mg/L as
total ammonia nitrogen.
Although vanadium produced toxicity in the effluent
in the 6 to 16 mg/L range, concentrations of
approximately 5 mg/L were designated as
concentrations of concern.
For polymer toxicity, the bioassay was not as simple.
Because the concentration of the polymeric flocculent
in the effluent is a function of its adsorption behavior
on activated sludge, toxicity tests to determine the
toxicity of free polymer were conducted with
synthetic seawater. The resulting 96-hour LCso f°r
polyethyleneimine (PEI) and DMAEM/AM were
determined to be in the range of 5-15 mg/L and 30-50
mg/L, respectively. Because these concentrations
represent free flocculent in solution and not applied
dosage during waste treatment, adsorption isotherms
were developed for biomass generated in the
activated sludge pilot units treating the MMC
wastewater. Both the PEI and the DMAEM/AM
polymers were used as adsorbates. Isotherms were
determined by adding known amounts of flocculent to
1-L samples of biomass, mixing, settling the biomass,
and analyzing the supernatant for residual flocculent
concentration. The amount of flocculent adsorbed to
the biomass was calculated by performing a material
balance on the liquid phase. This allowed for the
estimation of flocculent in solution given a specific
amount of biomass in the wastewater flow, flocculent
dosage rate, and the adsorptive capacity of the given
flocculent (either PEI or DMAEM/AM).
This study showed that not only did free PEI cause
toxicity to fish, but it also inhibited both the
biodegradation of oil and grease (specifically
naphthenic acids) and the nitrification process which
further contributed to toxicity because of the
A-16
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resulting high residual effluent concentrations of
naphthenic acid and ammonia.
Confirmation of Toxic Agents
Once potential toxic agents were identified, their
toxicity in the effluent had to be confirmed. This was
done using several methods. Through fractionation
procedures described above, the toxicity of the
effluent was shown to decrease once the oil and
grease fraction had been removed. Furthermore, the
individual addition of oil and grease, ammonia,
vanadium, and amines to a nontoxic effluent
increased the toxicity of that effluent to that expected
in a similar toxic effluent.
In order to quantify the extent to which each toxicant
contributed to the total toxicity, weekly acute toxicity
tests were conducted for approximately one year
using three-spined stickleback fish. In addition to the
toxicity test, each sample was analyzed for an
extensive list of potential pollutants. For each of
these pollutants, their toxicity was determined
through a literature search. Because the fractional
acute toxicities of waste constituents are generally
additive, it was hypothesized that overall toxieity
should be equal to the sum of each individual
constituent's toxicity. This is mathematically
expressed as TCt = Ca/TL50a + Cb/TL50b ---
Cn/TL50n
where
TG| = total effluent toxicity in toxic units
Ca,,,n = concentration of each individual waste
constituent
TL50a-n = concentration of waste constituent
which causes 50 percent mortality
Using this equation, a multiple linear regression
eauation was derived and the statistical significance
of each constituent in reference to the overall toxicity
could be determined. A correlation coefficient (R2) of
0.59 was derived. The regression explains
approximately 62 percent of the toxicity. Based on
this additive approach, significant contributors of
toxicity were identified as ammonia (18 percent),
naphthenic acids (32 percent), and suspended solids
(12 percent). The balance of 38 percent unexplained
toxicity was attributed to the variability of the
toxicity tests or the polymer, PEI, which was later
identified.
Joxicity Reduction Approaches
At this point, oil and grease (naphthenic acids),
ammonia, amines (organic nitrogen), flocculation
polymers (PEI), and suspended solids had been
identified in at least one of the studies performed as
contaminants of concern. Toxicity reduction
approaches for each of these contaminants are
discussed below.
Oil and Grease
The major source of naphthenic acids (oil and grease)
in MMC effluent was identified as wash water from
the crude oil desalter and the toxicity from this
source was attributed to partitioning of water soluble
naphthenic acids from the crude oil into the water
phase. A Brine Deoiling Unit (BDU) was
subsequently installed to reduce the concentration of
naphthenic acids discharged to the aqueous effluent
treatment facilities. Since the naphthenic acids are
water soluble, they still partition into the water
phase to some degree and subsequently continue to be
present in the aqueous effluent.
Bench scale tests indicated that powdered activated
carbon (PACT) addition to activated sludge can
reduce effluent toxicity (Shell Oil Company 1986). In
subsequent pilot scale slip-stream studies onsite, 50
mg/E (basis feed flow) of powdered activated carbon
completely removed acute toxicity to stickleback
after addition of 20 mg/L naphthenic acid to the
biotreater feed. In contrast, a conventional biotreater
fed the same spiked feed yielded an effluent with an
L& of about 60 percent. Emergency PACT addition
to the MMC biotreater for toxicity reduction
following upsets or spills may be possible. Potential
adverse effects or PACT (clarification, corrosion,
equipment wear) should be considered before full
scale use is implemented. However, recent biotreater
operating performance shows that when the proposed
10 mg/L oil and grease NPDES limitation is met, the
concentration of oil and grease (i.e., naphthenic
acids) is kept below the effect concentration and a
nontoxic effluent is produced.
Ammonia
The most effective method of controlling effluent
ammonia levels is to sustain nitrification in the
activated sludge basin. Since February 1985, the
Martinez refinery biotreater has sustained
nitrification, thereby reducing the effluent total
ammonia concentration to less than 1 mg-N/L. Proper
control of sludge age, pH, and inhibitory spills (i.e.,
source control) in addition to avoiding inhibitory
additives such as the polyethyleneimine type water
clarification polymers should allow for continued
nitrification and eliminate ammonia as a contributor
to fish toxicity.
Amines (Organic Nitrogen)
Ethylenediamine is produced as a waste gas in one of
the chemical manufacturing processes. Prior to May
1976, this gas was discharged in series through a
water scrubber and an incinerator, and the alkaline
A-17
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scrubber water was periodically drained to the sewer.
When it was realized that this waste was
aggravating effluent ammonia and toxicity, the
water scrubber was bypassed and the gas incinerated
directly. By this relatively simple modification, this
source of effluent toxicity was eliminated.
In the Diallylamine (DAAM) plant, wastewater is
discharged after distillation of amines in alkaline
solution. A specific ion electrode instrument,
sensitive to the total of ammonia and amines, was
installed to continuously monitor this wastewater
which is diverted to a storage tank and rerun
whenever ammonia or amine levels are high. The
ability to control amine losses and the impact of this
process on effluent quality was monitored closely
after the plant started operation in March 1977.
However, studies in 1979 showed that organic
nitrogen compounds were probably negligible
contributors to toxicity and the efforts to control the
toxic amines described above were apparently
successful.
Flocculation Polymers (PEI and DMAEM/AM)
Utilizing the adsorption equations developed to
estimate free (dissolved) flocculent, it was estimated
that free PEI flocculent would be present in the
effluent whenever the applied flocculent dosage
exceeds 40 mg/L. During TSS excursions, flocculent
doses in excess of 8 0 mg/L have been used at MMC.
Estimates on the PEI concentration in the final
effluent would be subject to a large degree of
uncertainty. However, there is a strong possibility for
PEI in the effluent and potential for toxicity due to
PEI. Therefore, use of this flocculent was
discontinued. In contrast, the DMAEM/AM
flocculent currently in use would have to be applied
at a dosage in excess of 150 mg/L before effluent
toxicity due to flocculent would be expected. This is
due to the stronger adsorption characteristics of
DMAEM/AM.
Suspended Solids
Suspended solids are in part biodegradable, and thus
are probably at least partially nonpersistent. The
quantity of suspended solids in the wastewater
discharge is very minor compared to naturally
occurring silt suspensions in the tidal estuary.
Therefore, the minor discharge of suspended solids
probably is of little consequence as related to
persistence of acute toxicity.
Follow-Up and Confirmation
As noted in the introduction, the three studies
described in this case study spanned over eight years,
and although oil and grease and ammonia were
identified as toxicity contributors in each study,
amines, specific flocculent polymers, and suspended
solids were identified in only one study.
Problems Encountered
Conducting a toxicity reduction evaluation on an
essentially non-acutely toxic effluent is difficult.
However, the investigators in this study took an
innovative approach. By correlating observed
effluent toxicity to manufacturing processes, changes
in processes could be related to periods when the
effluent became non-acutely toxic. Without testing
each process waste stream, the investigators could
narrow their work scope and focus on those processes
which were correlated with effluent toxicity.
Water Quality-Based Toxicity Limit
After confirming sources of toxicity and the non-
persistent nature of toxicants, MMC applied for an
exception to the CRWQCB toxicity limit of a 100
percent effluent LCso using the three-spine
stickleback. The exception was proposed based on
meeting three California criteria: (1) effluent
dilution is rapid and greater than 10 to 1 on
discharge, (2) effluent toxicants are non-persistent
and (3) beneficial uses of the receiving water are
protected.
Shell used U.S. EPA's water quality-based approach
as outlined'in the Agency's Technical Support
Document (U.S. EPA 1985), to develop a protective
water quality-based toxicity limit.
Acute toxicity tests using six species, and chronic
toxicity tests using three species, were conducted
over a 12 month period to determine sensitive species
and acute to chronic ratios. Additionally, these data
were used to relate effluent toxicity to the three-spine
stickleback to the organisms used in this study.
Furthermore, dye and effluent modeling studies were
performed to determine plume dilution. This
demonstration supported a dilution of 33:1 and a
protective water quality-based effluent limit of LC$o
> 54 percent effluent.
References
Hanson, J.R. "Progress Report on Wastewater
Discharge Toxicity Study Program. Shell Oil
Company Martinez Manufacturing Complex."
Submitted to California Regional Water Quality
Control Board, December 1, 1976.
Hanson, J.R. "Technical Report on Toxicity of Waste
Discharge. Shell Oil Company Martinez
Manufacturing Complex." Submitted to California
Regional Water Quality Control Board, June 26,
1980.
A-18
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Shell Oil Company. "Derivation of Water Quality- Control. EPA 440/4-85-032 Office of Water,
Based Toxicity Effluent Limits for the Shell Oil Washington, B.C. (1985).
Martinez Manufacturing Complex." Prepared by
EA Engineering, Science and Technology, Inc.
Lafayette, California. (1986). 48 pp.
vanCompernolle, R, et al. Potential Contributors to
U.S. Environmental Protection Agency. Technical Fish Toxicity in the Martinez Manufacturing
Support Document for Water Quality-Based Toxics Complex Biotreater Effluent. August 9,1985.
A-19
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Section A-4
Case History: A North Carolina Textile Mill
/ntroc/uct/on
Glen Raven Mills, Inc., Consumer Products Division,
produces ladies hosiery at its mill in Alamance
County, Altamahaw, NC. Treated process and
domestic wastewater from the mill is discharged into
the Haw River and comprises 0.8 percent of the river
volume under 7Q10 flow conditions (seven
consecutive day flow with a recurrence interval of ten
years). Having determined that WWTP effluent was
toxic, The North Carolina Department of
Environmental Management required Glen Raven to
implement an aquatic toxicity monitoring program
in early 1985, establishing a 48-hour acute static
Daphnia pulexLC^o of >90.0 percent as a toxicity
reduction goal.
Effluent bioassay testing began in February 1985.
The following month, Glen Raven Mills enlisted
Burlington Research, Inc. (BRI) to conduct Toxicity
Identification and Reduction Evaluations. The final
phase of the study was completed in March 1986.
Initial Data and Information Acquisition
Process Description
Glen Raven Mills dyes pantyhose (Nylon 6 and 6.6)
with acid and disperse dyes in rotary dyeing
machines. Prior to the TRE, liquor ratios of 30:1 (30
pounds of water per pound of goods dyed) were typical
for the dyeing machines being used. Among the
major process chemicals used in addition to dyestuffs
are surfactants, chelating agents and fabric
softeners, which serve as fabric processing aids prior
to dye applications.
The raw process water being utilized in the dyeing
systems is obtained from the Haw River, upstream of
the plant. Water is flocculated with alum and
clarified prior to use.
Wastewater Treatment Plant Description
Glen Raven maintains an activated sludge WWTP
for the treatment of process and domestic
wastewaters. The plant consists of upright fiberglass
equalization tanks, an 80,000 gallon capacity
concrete activated sludge basin, and concrete
rectangular clarifier and chlorine contact chambers.
Permit flow for the WWTP is 0.045 MGD but flows
prior to the TRE averaged 0.027 MGD, with frequent
hydraulic overflows appearing during production
peaks.
Wastestreams treated by Glen Raven's WWTP are
primarily composed of discharges from dye processes
and discharge of proprietary yarn spinning
applications. Over 90 percent of the process flow
comes from dyeing operations but there is some
contribution of domestic wastes even though septic
tank treatment is applied to most domestic waters.
Characteristics of Influent and Eff luent
Glen Raven is required to measure selected effluent
chemical parameters twice monthly. A review of
composite effluent measurements prior to the
initiation of the TRE indicates average parameter
levels of 43.5 and 365.8 mg/L for BOD5 and COD,
respectively; 33.9 mg/L for TSS, <0.01 mg/L for
sulfide, < 0.01 mg/L for phenols and < 0.05 mg/L for
total chromium. Metal analyses conducted in May
and June reflect average copper levels of 0.446 mg/L
and average zinc levels of 0.498 mg/L. Generally, the
effluent can be characterized as having a high COD
pass-through and potentially toxic concentrations of
total metals.
A review of monthly 48-hour acute static D. pulex
LCso values for tests conducted on composite
effluents during the early months of toxicity
monitoring indicates that values ranged from a low of
38.1 percent to a high of > 90.0 percent, and averaged
63.6 percent. Though the LCgg goal of > 90.0 percent
was met in March, June and July 1985, the effluent
has a history of dramatic fluctuations in LCso values
(Figure A4-1).
Toxicity Reduction Evaluation (TRE)
Effluent Toxicity
The water flea D. pulex was used as the test species
prior to and during the TIE acute static toxicity
monitoring program of Glen Raven's effluent. Test
organisms were obtained from cultures maintained
A-21
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o"
cf
2/85
Date
1/86
Figure A4-1. Early TRE 48-hour 0. pu/ex acute static bioassay
history, Glen Raven Mills.
by BRI and bioassay procedures adhered to EPA
protocol (Peltier and Weber 1985).
Glen Raven began bioassay monitoring of its effluent
in February of 1985. Concurrently, Glen Raven asked
BRI to screen its chemical usage list so that
compounds with known toxicities and minimal
biodegradability could be eliminated/minimized in
production processes. Chemical compounds for which
dyehouse products were screened included alkyl
phenol ethoxylates (APE), biocides, quaternary
ammonium compounds and organic solvents. In
addition to chemical use recommendations, BRI
suggested means by which chemical products could
be more accurately measured and dispensed during
dyeing operations. Prior to this review, dippers and
buckets were used to measure the dyehouse process
chemicals. During this phase of the TIE (Tier I),
personnel in the dyehouse began to use measuring
cups and weighing devices to more accurately
apportion the amounts of chemicals required in
dyeing formulae. Despite the implementation of
chemical compound optimization by July, 1985,
effluent bioassay results continued to fluctuate well
below the LCso goal of >90.0 percent (Figure A4-1).
During the chemical usage review period, BRI also
studied WWTP operational practices and data (TRE,
Tier II). Because of the regularity of influent
overloads, it was suggested that Glen Raven consider
additional equalization to supplement present
capacity. In addition, it was suggested that Glen
Raven consider the use of dyeing machines that
would reduce liquor ratios from 30: 1 to less than 10: 1.
Such machines would help to minimize the volume of
process wastewaters entering the WWTP.
Characterization and Fractionation
Because effluent toxicity levels did not improve after
the Phase I chemical optimization step, and because
the feasibility of increased equalization and low-
liquor dyeing was undecided (Tier II), BRI undertook
a Tier III TIE to further characterize Glen Raven's
effluent. Due to BRI's familiarity with Glen Raven's
textile operation and chemical use, initial
wastestream analyses focused on effluent metal and
surfactant measurements.
A 24-hour composite effluent sample was collected
prior to chlorination beginning December 17, 1985
and used for chemical and toxicity characterization.
In addition to BOD5 and COD determinations,
metals and surfactant (MBAS and CTAS)
determinations were conducted. Of particular
interest in this characterization was the
identification of unbiodegraded surfactant
compounds in Glen Raven's effluent, particularly
nonionics. To this end, a sublimation/extraction
procedure, developed by the Soap and Detergent
Association for use in biodegradation and
environmental studies, was applied to an effluent
aliquot. This method, as well as those for all NPDES
analyses conducted during the TIE and TRE, is
referenced in Standard Methods (APHA 1985).
Results of the December effluent characterization
indicated that the sample was representative of that
typically obtained for Glen Raven. Analyses showed
that toxic concentrations of copper, nickel, and zinc
(total and dissolved) were present. Furthermore, the
CTAS (nonionic surfactant) concentration of 20.7
mg/L indicated that nonbiodegraded nonionic
surfactants were a very likely source of the effluent
toxicity indicated by the 48-hour D. pulex static acute
LCso value of 48.7 percent effluent. In addition, the
1.6 mg/L concentration of MBAS surfactant was
considered high enough to be potentially toxic,
pending identification of structural conformation.
Table A4-1 summarizes pertinent data from the
December analyses along with U.S. EPA Criteria
Document literature toxicity values for daphnids and
expected instream waste concentrations during
projected 7Q10 flow conditions.
Effluent metals could be directly linked to dyestuffs
used in the hosiery dyeing process but it appeared
unlikely that additional source reductions could be
effected since chemical optimization had already
been implemented. And to what extent metals were
contributing to the effluent toxicity was unclear as
metal determinations were conducted as 'total
recoverable' (standard procedure for effluent metal
A-22
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Table A4-1. Effluent Characterization, Glen Raven Mills
TRB, Prechlorination Composite of
December 17-18,1985.
Test
* Acute LC50
Copper
Nickel
Zinc
CTAS
MBAS
Result
(mg/L)
Total
(Dissolved)
48.7%
0.443 (0.447)
0.110 (0.100)
0.537 (0.480)
20.7
1.6
Daphnid Toxicity
Criteria (mg/L)
Acute
0.017
1.102
0.076
5.360
19.870
Chronic
- -
0.010
0.015
-
>1.0(a)
>4.0(b)
Effluent
7Q10 IWC
at 0.8%
0.004
0.001
0.004
0.166
0.013
(a) Linear Alcohol Ethoxylate (LAE)
(b) Sodium Dodecylbenzenesulfbnate (DDBSA) as MBAS
Value is in percent effluent
analyses) rather than 'acid soluble,' the latter which
is thought to be more indicative of a concentration
which is toxic (U.S. EPA 1985).
As with other chemical compounds, surfactant usage
had been optimized to eliminate those containing
highly toxic and nonbiodegradable APEs. It was
apparent from the December effluent
characterization that the linear alcohol ethoxylate
(LAE) compounds being used by Glen Raven were not
being adequately treated to non-toxic levels.
Toxicity Reduction Approaches
In order to evaluate the contribution of metals and
non-biodegraded surfactants to Glen Raven's effluent
toxicity, BRI proposed a Tier V study which
addressed metals removal and extended biotreatment
as a means of reducing effluent toxicity. Both
laboratory treatments were conducted on
prechlorination composite effluent samples collected
daily from January 14-18, 1986. Baseline
measurements of acute toxicity (LCso values), BOD,
COD, metals, and CTAS surfactants were conducted
on the December 14-15 composite, which was used for
the metals reduction experiment and the initiation of
the extended biological treatment experiment.
Metals Reduction Experiment
For this treatment experiment, an aliquot of
untreated effluent was passed through a prepared
column packed with a cationic exchange resin
(Biorad AG50W-X4, 50-100 mesh, hydrogen form).
Portions of treated effluent were then used for
bioassay analyses and measurements of total
recoverable metals. Results of pre- and post-
treatment analyses indicated substantial reductions
of copper (from 0.244 to 0.078 mg/L) and zinc (0.598 to
0.024 mg/L). The pre-treatment iron concentration of
1.061 mg/L was minimally reduced to 0.930 mg/L,
while cadmium, chromium, lead and nickel
concentrations were < 0.05 mg/L in both pre- and
post-treatment samples. A post-treatment LCso value
of 80.7 percent effluent reflected some improvement
from the baseline LCso value of 71.9 percent.
Extended Biological Treatment Experiment
For this treatment experiment, activated sludge from
Glen Raven's WWTP was used to further treat
aliquots of composited effluents. Prior to the actual
renewal/treatment phase of the experiment,
activated sludge was acclimated in BRI's
temperature controlled laboratory, a period which
included daily feeding with untreated wastewater
from Glen Raven's treatment facility.
On Day 1 of the Treatability Study (January 15,
1986), background values for activated sludge
parameters were measured on sludge culture
supernatant, including total suspended solids,
settleable solids and 48-hour static acute LCso values
(the latter determined on culture supernatant). In
addition, a respiration rate was obtained for the
sludge culture to check for an endogenous respiration
level (5-20 mg/L/hr). Subsequent to this background
check, a daily renewal of sludge supernatant was
initiated at a 20 percent by volume rate over a 5-day
period, beginning with the January 14-15 composite.
A freshly composited effluent sample was used each
day thereafter during the renewal period. After the
fifth and final 20 percent renewal, at which point the
total volume of sludge supernatant had been
replenished with composited effluent, activated
sludge treatment was extended for a period of 24
hours. At the end of this 24-hour period, aliquots of
sludge supernatant were collected and metal, BOD5,
COD, CTAS, and acute and mini-chronic (N.C.
DNRCD 1987) static toxicity tests conducted.
Post-treatment metal determinations indicated that
0.287 mg/L copper, 0.065 mg/L chromium, 1.071 mg/L
iron and 1.14 mg/L zinc were present. Of these, only
zinc reflected a substantial increase over the pre-
treatment concentration of 0.598 mg/L. Post-
treatment values of 17.8 mg/L for BOD5, 231.2 mg/L
for COD, and 0.85 mg/L for nonionic surfactants
(CTAS) reflected substantial reductions from pre-
treatment concentrations of 79.5, 500.2 and 10.4
mg/L for BOD5, COD and nonionics, respectively.
The post- treatment 48-hour acute static LCso value
of > 90.0 value also reflected reduction in toxicity
from the baseline LCso of 71.9 percent. Results of the
mini-chronic Ceriodaphnia reproduction bioassay
indicated that the treated effluent had no effect at
Glen Raven's 7Q10 instream effluent concentration
of 0.8 percent.
A-23
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Conclusions: Toxicity Reduction Experiments
Based on preliminary BODS, COD, metal and acute
static LCso values, the composite effluent samples of
December 17-18 and January 14-15 were
representative of effluent samples typically obtained
from Glen Raven's Altamahaw facility.
Metal removal experiments on Glen Raven effluent
showed that metals did not appear to be major
contributors to effluent toxicity. Compared to
published metal toxicity criteria, the December
effluent metal concentrations of copper at 0.443
mg/L, nickel at 1.110 mg/L and zinc at 0.537 mg/L
would appear to support the 48.7 percent static acute
test LCso value obtained for the composite. However,
similarly toxic concentrations of copper and zinc
(0.244 mg/L and 0.598 mg/L, respectively) were
present in the January 15 composite and the LCso
value was considerably higher (71.9 percent).
Likewise, toxic concentrations of copper (0.278 mg/L)
and zinc (1.14 mg/L) were present in the treatability
experiment supernatant which had a measured LCso
value of >90.0 percent. In explaining this
discrepancy, it must be kept in mind that flame
atomic absorption determinations represent metals
in their free and complexed states. Textile process
water such as Glen Raven's may contain metals that
have complexed with chelating agents such as EDTA
and, therefore, are not as toxic as metals in their free
ionic state.
Unbiodegraded nonionic surfactants were present in
Glen Raven effluent at concentrations reported as
toxic to aquatic organisms. Because Glen Raven
removed alkyl phenolic surfactants (such as NP-10)
from the production process as a result of the Tier I
chemical optimization, it was surmised that the
nonionic surfactant concentrated from the effluent
represented unbiodegraded linear alcohol
ethoxylates (LAEs) which are known to be highly
biodegradable and non-toxic when completely
treated. A BRI in-house study, funded by the North
Carolina DEM Pollution Prevention Pays Program,
indicated that nonbiodegraded LAE is toxic to
Dccphnia pulex at concentrations of 2.4 mg/L (Moore,
et al. 1987). Infrared scans of surfactant residue from
both the December 18 and January 15 composites
confirmed that the LAEs present in the effluent were
incompletely biodegraded, as evidenced by reduced
terminal hydroxyl peaks at 3387 nm and reduced
ethylene oxide peaks at 1220-1280 nm.
That the level of toxicity in Glen Raven's effluent
could be reduced with extended biological treatment
was indicated by the acute static LCso value of > 90.0
percent obtained with supernatant from the
Biological Treatment experiment. In addition,
results of the Ceriodaphnia mini-chronic bioassay
indicated that effluent receiving extended biological
treatment did not impair organism reproduction at
the 0.8 percent 7Q1.0 instream concentration.
Based on the findings of the laboratory Toxicity
Reduction experiments, the following conclusions
were made:
1. Glen Raven effluent can be rendered acutely non-
toxic upon receiving adequate biological
treatment.
2. Additional biological treatment will biodegrade
surfactants and other organics to non-toxic levels
and reduce COD loading on receiving stream
waters.
3. Based on present WWTP design and the
installation of two low-liquor dye machines, the
maximum flow of wastewaters into the WWTP
should be no greater than 20 percent of the
treatment facility capacity. Alternatively, the
WWTP could be expanded to allow for 20 percent
more contact time with the activated sludge.
4. Though concentrations of total recoverable
metals in the effluent exceed concentrations
reported to be acutely toxic to aquatic organisms,
present levels do not appear to be contributing
significantly to effluent toxicity.
Based on findings of the TRE, the most logical and
least expensive approach to toxicity reduction at the
Glen Raven Mill was to increase process waste
equalization to accommodate continual WWTP
operation on a 24-hours per day, 7 days per week, 52
weeks per year schedule. Because the mill had no
second and third shift or weekend operations, these
periods could be used for waste treatment. Additional
equalization would allow for a much slower addition
of influent to the WWTP, thereby giving the facility
the time necessary to adequately treat process
wastes.
/mp/emenfcrf/on of Toxicity Reduction
Recommendations
By August 1986, Glen Raven Mills had incorporated
significant changes at its Altamahaw facility. First,
low-liquor ratio dyeing machines were installed in its
dyeing process, reducing by 50 percent water usage
per pound of hosiery produced. Secondly, additional
equalization was incorporated into the design of the
WWTP, thus eliminating peak influent surges. These
changes increased the retention time of process
wastes in the activated sludge contact chamber from
an average of 2.5 days to 4.5 days.
A-24
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Follow-Up and Confirmation
Aquatic toxicity testing of Glen Raven's effluent
continued on a monthly basis for the remainder of
1986. After several months of >90.0 percent LCso
values in early summer, attributed to a warm
weather trend similar to that seen in 1985, Glen
Raven's effluent consistently maintained its LCso
goal well into the colder winter months. Beginning in
1987, Glen Raven's permit was modified to a
quarterly toxicity testing schedule and its effluent
has continued to test non-toxic. As Figure A4-2
depicts, the maintenance of a toxic effluent status is
closely correlated to the reduction in the average
monthly WWTP effluent flow rate.
o 11 I I I I I III 11 I II I I I 11 I I I II M I'll
Figure A4-2a. Pre- and post- TRE 48-hour 0. pu/ex acute
static bioassay history, Glen Raven Mills.
2/85
1/86
1/87 5/87
Figure A4-2b. Pre- and post- TRE monthly average effluent
flow (MGD), Glen Raven Mills.
The incorporation of additional WWTP sludge
contact time and the substitution of LAEs for APEs
as process chemicals were both critical to the success
of Glen Raven's TRE. Because of the literature
reported evidence of APE toxicity and limited
degradation, it is unlikely that Glen Raven would
have realized its toxicity reduction goal with
extended treatment alone. To date, Glen Raven has
continued to use process-related detergents which are
non-toxic when completely biodegraded. There is
every indication that this practice in conjunction
with expanded WWTP operations will ensure the
continued discharge of process effluent with minimal
toxic impact.
Problems Encountered
No specific hurdles were encountered during the TIE
and TRE phases of the study. Paramount to the
success of the project was Glen Raven Mills'
willingness to investigate all aspects of the toxicity
problem. Management acted quickly in assessing
study findings and implemented changes in chemical
optimization, process changes and WWTP
modifications in timely manner.
References
APHA. Standard Methods for the Examination of
Water and Wastewater. 16th Edition, American
Public Health Association, Washington, DC
(1985).
Moore, S. B., et al. "Aquatic Toxicities of Textile
Surfactants." Textile Chemist and Colorist
19(5):29-32 (1987).
North Carolina Department of Natural Resources
and Community Development, Division of
Environmental Management, Water Quality
Section. "North Carolina Ceriodaphnia Chronic
Effluent Bioassay Procedure." North Carolina
Department of Natural Resources of Community
Development, Raleigh, NC (1987).
Peltier, W. H. and C. I. Weber. Methods for
Measuring the Acute Toxicity of Effluents to
Freshwater and Marine Organisms. 3rd Edition,
EPA-600/4-85/013, Environmental Monitoring
and Support Laboratory, U. S. Environmental
Protection Agency, Cincinnati, OH., March 1985.
U.S. Environmental Protection Agency. Ambient
Water Quality Criteria for Copper 1984. EPA-
440/5-84/027, Environmental Protection Agency,
Criteria and Standards Division, Washington,
DC., January 1985.
A-25
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Section A-5
Case History: A North Carolina Metal Product Manufacturer
Introduction
Halstead Metal Products, located in Stokes County,
NC, produces copper piping through an extrusion
process. Halstead operates a 0.025 MGD activated
sludge WWTP which has a monthly average effluent
discharge of 0.0054 MGD. Incoming wastewater is
primarily domestic in nature, with no actual
contribution from industrial processes. Halstead's
effluent is discharged into an unnamed tributary of
the Dan River and has a 7Q10 IWC of 32.6 percent.
The North Carolina Division of Environmental
Management (NCDEM) conducted 48-hour acute
static Daphnia pulex bioassays on effluent samples in
June 1985 and January 1986. LC50 values of 37, 28,
24 and 7 percent showed that effluent was toxic to the
test organism and indicated that instream impact
would be expected under 7Q10 design stream
conditions. As a result of these preliminary
bioassays, the NCDEM required Halstead Metal
Products to begin a monthly program of 48-hour
acute static bioassay monitoring of its effluent.
Burlington Research, Inc. (BRI) began the monthly
testing in March 1986 and LCso values ranged from
<5.0 - 11.9 percent through October 1986. At
Halstead's request, BRI initiated a Toxicity
Reduction Evaluation (TRE) the following month.
Initial Data and Information Acquisition
Process Description
Halstead melts copper scrap and cathodes to form
billets (copper logs) which are then used for the
extrusion of tubes and cold-drawing of pipes/tubing of
various lengths and diameters. Monthly production
of finished product averages 5 million pounds.
Wastewater Treatment Plant Description
Halstead operates a package activated sludge WWTP
consisting of a 25,000 gallon aeration basin, 4,000
gallon clarifier and a 525 gallon chlorine contact
chamber. Permitted discharge for the WWTP is 0.025
MGD but a 0.0058 MGD monthly average is
produced.
Housekeeping
Prior to the initiation of the TRE, Halstead conducted
a review of housekeeping practices. A possible
contributing source of toxic copper flakes through
floor drains was corrected by the installation of drain
traps. Except for the introduction of copper dust via
frequent hand washing by production personnel, no
additional source of contamination was identified.
Characteristics of Influent and Eff luent
Halstead's NPDES permit requires both influent and
effluent analyses on a variable daily/weekly/monthly
schedule. A review of 16 months of NPDES data,
summarized in Table A5-1, indicates substantial
reductions of BODg, ammonia nitrogen and total
suspended solids through the WWTP.
Table AS-I. Influent and Effluent Data Summary, Halstead
Metal Products, August 1985 November 1988
Concentration (mg/L)
Parameter
Flow (MGD)
pH
BOD5
COD
Oil and Grease
Ammonia Nitrogen
Residual Chlorine,
Total
Solids, Total
Solids, Total
Suspended
Influent "
-
7.51
2179
6.8
581
77
Effluent
0.0058
6.48
96
66
58
0.8
0.6
422
31
Reduction
-
89
28
60
Chemical Usage Review
Except for two hand cleaning products, Halstead uses
no chemical products in conjunction with its copper
pipe production. It was noted that personnel involved
in the manufacturing process washed their hands
frequently to clean them of machinery oils and
grease. Whether soap product use at Halstead was
high enough to be contributing to the effluent toxicity
was questioned in absence of aquatic toxicity
A-27
-------
information for the cleaners. It is well documented
that detergents/surfactants in their unbiodegraded
state can be toxic to aquatic organisms at levels < 1.0
mg/L. Another concern regarding soap was its
characteristic 'wetting' property and how it might be
enhancing the toxicity of substances such as copper
dust by acting as a mode for migration to the
respiratory structures of toxicity test organisms.
On-site Visit
In late October 1986, an on-site tour of Halstead's
production and WWTP facilities was conducted. A
tour of the manufacturing facility did not highlight
any disposal problems. Except for the frequent hand
washing by employees, which contributes greases
and copper into the waste lines, no contaminating
point sources were identified that would account for
the copper, grease, or other unidentified pollutants
which could be responsible for the severe effluent
toxicity. Operation of the WWTP appeared to be
optimal though oil and grease surface film in the
separator suggested an area that might require
addressing. An accumulation of copper bits at the
point of influent discharge to the activated sludge
basin suggested the distinct likelihood of an
accumulation of copper particles in the treatment
basin, especially since the basin had not been
completely cleaned out during the previous 6-7 years.
During the on-site visit, a preliminary check on
water from Halstead's source wells indicated that
incoming water had a pH of 6.27 and a very low
background copper concentration. Furthermore,
though copper piping was used throughout
Halstead's facility when it was built, it was unlikely
that any significant leaching from copper pipes was
occurring at that pH level. A more thorough history
of pH and total metal levels was recommended due to
the rotating nature of pumping from the 5 wells
which serve as the incoming water source for
Halstead. It was also suggested that metal levels be
monitored at various taps and fountains throughout
the facility.
Toxicity Identification Evaluation (TIE)
Eff luent Toxicity
Logically, copper was suspected as the primary
toxicant in Halstead's effluent. Therefore, when
monthly bioassay monitoring was initiated in March
1986, total recoverable copper determinations were
conducted on all effluent composites collected for
bioassay testing. EPA guidelines (Peltier and Weber
1985) and Standard Methods (APHA 1985) were
followed for all analyses.
During the eight month period of bioassay and copper
monitoring prior to the TRE, 48-hour acute static
Duphnia pulex LCso determinations consistently
ranged from < 5.0 - 11.9 percent and averaged 6.5
percent. Total recoverable copper concentrations for
the same period ranged from 0.436 - 1.931 mg/L and
averaged 0.566 mg/L. EPA criteria documentation
indicates that copper is toxic to freshwater organisms
at levels as low as 0.007 mg/L (U.S. EPA 1985).
Based on available NPDES data, copper was
suspected as the primary cause of effluent toxicity in
Halstead's discharge, with copper dust and filings
from manufacturing processes entering the WWTP
considered as the source. Oils and greases and
detergents were suspected to be contributing to the
overall effluent toxicity but confirmation through
additional chemical testing was needed. Because of
the domestic nature of the WWTP influent, other
sources of toxicity were not suspected.
Characterization and Fractionation
A multi-phase approach was taken during this aspect
of the Toxicity Identification Evaluation. Based on
findings and suspicions of the Background Review, a
3-week Phase I study was designed to further
characterize Halstead's wastestream. Objectives
include:
1. The daily monitoring of the incoming water
supply over a period of several weeks in order to
identify any background metal contamination
from well aquifers.
2. Because of questions regarding the contribution
of detergents to the toxic nature of the effluent, a
request for manufacturer's information on hand
cleaners was made.
3. Monitoring of WWTP influent and effluent for a
period of 3 weeks to establish incoming and
outgoing levels of metals, surfactants, and oils
and greases. Data would help establish:
a. Whether or not effluent copper levels were
due to accumulated solids in the treatment
basin.
b. The extent to which surfactants and oils and
greases were components of the influent and
how well they were being biotreated.
4. Determination of whether metals toxicity,
primarily copper, was due to particulate or
dissolved forms.
5. After the establishment of the above outlined
database, a series of laboratory experiments
would be designed for the removal of identified
toxins from Halstead's effluent wastestream.
Effluent samples would be checked for toxicity
before and after laboratory treatments.
A-28
-------
Beginning with the initiation of Phase I in November
1986, the water flea Cerioduphnia dubia/affinis was
used for all 48-hour acute static bioassays; those
required by the NCDEM as monthly tests as well as
those conducted as part of Halstead's Toxicity
Reduction Evaluation. It has been the practice of the
NCDEM to implement a chronic static bioassay after
a discharger meets its acute static LCso goal. By
utilizing Cerioduphnia for all future acute static
bioassay testing, differences in species sensitivity to
toxicants could be avoided as the chronic static
bioassay is incorporated as an effluent monitoring
tool.
In summary, Phase I influent and effluent
Ceriodctphnia 4&-hour acute static bioassay data
indicated consistent levels of toxicity at both
wastestream point sources during the 3 weeks of
testing. Chemical data indicated:
1. Total copper effluent levels were high enough to
account for the mortality observed in acute static
bioassays.
2. Effluent zinc levels were high enough to be
contributing to effluent toxicity.
3. Solids in the aeration basin were contributing to
effluent copper and zinc levels.
4. Copper levels in water from Well #& were high
enough to be acutely toxic.
5. Influent levels of surfactants, oils and greases,
and other organics measured as COD, were
adequately treated so that effluent
concentrations were not considered significant
contributors of toxicity.
Based on results of the Phase I study, a Toxicity
Reduction method evaluation was initiated in
February 1987. The primary goal was the
experimental reduction/removal of effluent copper to
non-toxic levels through laboratory-scale application
of industrial metal reduction technologies. Success of
metal reduction treatments was gauged by the extent
to which treated effluent samples met the 48-hour
acute static LCso goal of 90 percent or better. Another
goal of this work was the confirmation and further
identification of effluent toxicants through the
application of the newly drafted EPA Toxicity
Characterization bioassays (Mount and Anderson-
Carnahan 1988).
Three metal reduction experiments were conducted,
with the design of Experiments 2 and 3 based on
results of the previous experiment. Experiment 1
consisted of metal reduction through application of
lime, 50 percent liquid caustic, two cationic polymers,
and combinations thereof. Experiment 2 expanded on
Experiment 1 which indicated that lime-treated
effluent aliquots had the greatest copper reduction.
Lime addition also represented the least expensive
and easiest of the metal reduction treatments with
post-treatment bioassays. Each experiment was
conducted during consecutive months so that data
from regular monthly bioassay and copper
determinations (zinc measurements were added in
May 1987) could be applied as Experiment
pretreatment baseline data.
Metal and Toxicity Reduction Experiments
Data from Experiment 1 indicated that the best
reduction of effluent total copper was obtained by the
addition of lime to a pH level of 12.0, resulting in a
treated effluent copper concentration of 0.05 mg/L. In
Experiment 2, post-treatment total recoverable
copper levels of 0.04 mg/L for the pH 12 treatment
and 0.14 mg/L for the pH 11 treatment were
measured and in Experiment 3, concentrations of
0.12 and 0.04 mg/L measured for pH treatments 10
and 12, respectively. These values closely approached
reported 48-hour acute static copper LCsg values of
0.017 mg/L for Ceriodaphnia and 0.053 mg/L for
Daphnia pulex (U.S. EPA 1985). When compared to
aquatic toxicity literature values, the lowest of the
Experiment 1 and 2 post-treatment copper levels
equaled or surpassed reported LCso concentrations.
Results of Experiment 3 post-treatment toxicity tests
indicated, however, that effluent values of > 90.0
percent could be obtained despite post-treatment
total copper levels of 0.04 and 0.12 mg/L. (Post-
neutralization sulfate concentrations of 73.0 and
289.0 mg/L after pH adjustment were much lower
than the 48-hour acute static LCso concentration of
1,637.6 mg/L obtained for D. pulex during BRI in-
house studies.) This apparent contradiction brings to
focus two points regarding the contribution of copper
(as well as zinc and other low-level metals) to
Halstead's effluent toxicity.
First, it is not clearly understood what portion of an
effluent metal concentration is biologically available
to an aquatic organism and consequently capable of
producing toxic affects. It is apparent from the results
of Experiment 3 that not all of the copper present in
the treated effluent samples was bioavailable
because literature-cited toxic concentrations were
measured in effluent which passed the acute static
test. Further confirmation of this phenomenon is
evidenced by the bioassay conducted on the March 25
effluent composite. An LCso of > 90.0 percent was
obtained on effluent with total recoverable copper
concentration of 0.57 mg/L. Recently drafted EPA
Toxicity Characterization procedures assisted in
answering the question regarding bioavailability of
toxicants such as metals to aquatic organisms.
(Results of Characterization toxicity tests conducted
on Halstead's effluent are discussed below.) Another
factor hindering accurate correlation of metal levels
and toxicity is the methodology by which metal
A-29
-------
concentrations are routinely measured. NPDES
permitees are required to measure effluent metals as
'total recoverable' concentrations, the same method
applied by BRI during Halstead's TRE. In its most
recent criteria documentation, the EPA suggests that
effluent metals measured as 'acid soluble'
concentrations provide a better indication of the
amount of a metal which is potentially toxic to
aquatic organisms (U.S. EPA 1985).
BRI conducted both 'total recoverable' and 'acid
soluble' copper and zinc determinations on Halstead's
June 1987 effluent composite to see if there was a
measurable difference between detection methods.
Data indicated little difference in copper
concentrations between methods, with values of 0.85
mg/L 'total recoverable' copper and 0.89 mg/L 'acid
soluble' copper measured. Zinc levels, on the other
hand, were substantially different, with 0.246 mg/L
'total recoverable' versus 0.169 mg/L 'acid soluble'
concentrations measured. As with any experimental
procedure, a single set of data is inadequate for
drawing firm conclusions but this single comparison
of metal determination of methodology suggested
differences in effluent metal bioavailability.
The North Carolina freshwater standards for copper
and zinc are 0.015 and 0.050 mg/L, respectively.
Based on measurements of copper in lime-treated
effluents from laboratory and field samples, the 0.015
mg/L standard would not be met under 7Q10
conditions even though acute static LCso values of
>90.0 percent were measured. These metal
standards are considered Action Levels, however, and
can be waived if it is demonstrated that instream
levels are not toxic to aquatic life.
Field Application of Laboratory Procedures
The use of lime as a means by which metal levels can
be lowered with a subsequent reduction in effluent
toxicity was demonstrated in the laboratory. An
application of the same chemical technique was
demonstrated in March 1987 during a routine WWTP
operation. On March 6,100 pounds of lime was added
to the WWTP aeration basin and clarifier, and on
March 11 solids were pumped from the basin.
Another 50 pounds was added to the aeration basin
and clarifier on March 12. At month's end, the 24-
hour composite effluent sample collected for
Halstead's monthly acute bioassay had an LCso of
>90.0 percent (Figure A5-la). The following month,
an LCso value of 73.4 percent was obtained for
effluent collected over a 24-hour period beginning
April 7. These dramatic reductions in effluent
toxicity were obtained despite effluent total
recoverable copper concentrations of 0.57 and 0.16
mg/L (Figure A5-lb).
O
30-r
20-
10'
>00.0%
73.4%
I I I I I I I I I'M I I I I I I
3/86
8/86
Date
1/87
6/87
Figure AS-1 a. 48-hour daphnid acute static bioassay history,
Halstead Metal Products.
0.0
4/86
Date
1/87
6/87
Figure AS-1 b. Total recoverable copper concentrations,
corresponding composite effluents.
Toxicity Characterization Procedures
Results of timed-lethality procedures confirmed the
contribution of metals and an oxidant to Halstead's
effluent toxicity. ETso values of <48.0 hours
obtained during the chelation procedure indicate that
metals in the effluent complexed with EDTA to form
non-toxic compounds that were not biologically
available to test organisms. ETso values during the
air-stripping and solid phase extraction procedures
(Mount and Anderson-Carnahan 1988) for
treatments basified by the addition of sodium
hydroxide also showed significant reductions in
toxicity. The addition of sodium hydroxide to pHs of
11 and 9 during the air-stripping and solid phase
extraction procedures, respectively, undoubtedly
caused the formation of copper hydroxide salts which
were not available to the Ceriodaphnia.ETsQS of 23.7
and 19.8 hours obtained during the
oxidation/reduction procedure (Mount and Anderson-
Carnahan 1988) indicated that an oxidizing agent
was a significant contributor to the toxicity of the
tested effluent. The minimal chemical usage at
Halstead pointed to chlorine as the likely oxidant.
Effluent chemistry data indicated that 0.32 mg/L
A-30
-------
residual chlorine was present in wastewater used in
the Characterization tests, a concentration several
times greater than the reported 48-hour acute static
LCso of 0.028 mg/L and a chronic concentration of
0.007 mg/L for D.magna (5).
Beginning in February 1987, the NCDEM required
that effluent samples for aquatic bioassay testing be
collected after points of chlorination and that
dechlorination not be conducted prior to toxicity test
set-ups. Effluent residual chlorine levels since the
change in collection points have been high enough to
account for mortalities in acute static toxicity tests. It
should be noted that effluent LCsos were similarly
low when composites were collected prior to
chlorination; that is, before February 1987 (Figure
A5-la). Similarly, WWTP influent was identified to
be equally toxic during the Phase I study.
Receiving Stream Effluent Concentrations
Based on effluent values for the current year,
projected 7Q10 concentrations of total recoverable
copper and residual chlorine in Halstead's effluent
surpass toxicity limits reported in the scientific
literature. Though it has been demonstrated that
reported copper criteria limits do not necessarily
correlate with LCso and copper values obtained in
this TRE, literature values can serve as valuable
guidelines in the removal/reduction of effluent
contaminants.
1. More frequent solids wasting in the WWTP
aeration basin should be practiced.
2. Halstead's WWTP should be modified to
incorporate a metal reduction treatment system.
The use of industrial grade lime appears to be a
practical and inexpensive approach.
3. Effluent residual chlorine levels should be
reduced below current levels either by additional
aeration, cascading or chemical treatment.
It was BRI's opinion that minor engineering
modifications to Halstead's present WWTP facility
would accomplish the effluent metal and chlorine
reduction needed to produce a wastestream that is
neither acutely nor chronically toxic to receiving
stream organisms.
Follow-Up and Confirmation
Halstead Metal Products is presently conferring with
a civil and environmental engineering firm to
address TRE study findings and recommendations.
References
APHA. Standard Methods for the Examination of
Water and Wastewater. 16th Edition, American
Public Health Association, Washington, DC
(1985).
Conclusions and Recommendations for
Toxicity Reduction
Data collected during Halstead's Toxicity Reduction
Evaluation confirmed copper as the primary
compound responsible for effluent toxicity, and zinc
and chlorine as secondary contributors. Results of
acute static toxicity tests and Toxicity
Characterization procedures indicated that effluent
toxicity was reduced when these compounds were
complexed or removed through chemical treatment.
Furthermore, data indicated that the LCso g°al °f
90.0 percent or better could be met even though
effluent total recoverable copper and residual
chlorine concentrations exceeded aquatic toxicity
criteria. The following recommendations were
submitted to Halstead for consideration:
Mount, D. I. and L. Anderson-Carnahan." Methods
for Toxicity Reduction Evaluations: Phase I -
Toxicity Characterization Procedures." Second
Draft June 1988.
Peltier, W. H. and C. I. Weber. Methods for
Measuring the Acute Toxicity of Effluents' to
Freshwater and Marine Organisms. 3rd Edition,
EPA-600/4-87/013, Environmental Monitoring
and Support Laboratory, U. S. Environmental
Protection Agency, Cincinnati, OH., March 1985.
U S. Environmental Protection Agency. Ambient
Water Quality Criteria for Copper - 1984. EPA-
440/5-84/027, Environmental Protection Agency,
Criteria and Standards Division, Washington, DC,
January 1985.
A-31
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Section A-6
Case History: Texas Instruments Facility in Attleboro, Massachusetts
Introduction
In 1982, when Texas Instruments' (TI) Attleboro,
Massachusetts facility submitted a renewal
application for its National Pollutant Discharge
Elimination System (NPDES) permit, water quality
criteria were used to determine permit limits. The
draft NPDES permit, issued to TI in 1984, reflected
these water quality-based permit limits.
The Attleboro facility was unable to meet the new
limits with existing technology. After much
deliberation, TI chose to conduct a toxicity reduction
evaluation (TRE) using aquatic toxicity testing to
determine source of toxicity, and identify a means to
reduce the source. The following sections document
the work of the TRE. The TRE identified insoluble
sulfide precipitation as the method for treatment of
TI's effluents to achieve acceptable levels of aquatic
toxicity in the facilities' surface water outfall.
Initial Data and Information Acquisition
Initially, Springborn Bionomics Inc., a consultant to
TI, inspected the wastestreams and identified six
sampling sites for acute toxicity studies to evaluate
the effect of TI's direct discharges to surface receiving
waters (Figure A6-1). There were three ouffalls (003,
004, 005) which carried process water flows from TI
to Coopers Pond via a brook. After examining the
effluent from these outfalls, it was apparent that the
major contribution to toxicity in the receiving stream
was outfall 003. Most of the work focused on outfall
003 because the runoff from the metal finishing
processes were discharged into outfall 003. The other
outfalls received boiler blowdown, storm water
runoff, which had nothing to do with the product.
Dissolved metals appeared to be the major cause of
the observed toxicity. Table A6-1 summarizes
toxicity results from the various sampling locations.
Studies conducted at outfall 003 indicated that the
seven consecutive day flow with a recurrence interval
of 10 years (7Q10) was approximately 0.15 cubic feet
per second (cfs) or 0.0042 cubic meters per second
(cms) while the thirty-day average flow with a
recurrence interval of 2 years (30Q2) was estimated
to be .45 cfs or 0.013 cms. EPA Region I required
these historic low flows to be used in conjunction with
the sensitive species criteria to assess the impacts of
discharges on surface waters.
TI's process and cooling water flows were estimated
to contribute 93 percent of the stream flow during
acute toxicity conditions (periods of 7Q10 flow and
maximum plant flow) and 73 percent of the total flow
during chronic toxicity conditions (periods of 30Q2
flow and average plant flow).
Toxicity Identification Evaluation (TIE)
Eff luent Toxicity
Two studies conducted on Daphnia pulex by
Springborn Bionomics Inc. indicated that the process
water discharge from 003 exhibited No Observed
Acute Effect Levels (NOAEL) of 5.6 and 14 percent
effluent. Similar studies conducted on fathead
minnows yielded NOAELs of 56 and 100 percent
effluent. These results indicated that D. pulex was
the most sensitive species and that based upon this
species, effluent from 003 was toxic and subject to
reduction.
Because the final effluent exhibited high acute
toxicity to D. pulex TI decided to conduct a second
round of toxicity testing using acute toxicity testing
and instream evaluation with D. pulex and chronic
toxicity testing with ceriodaphnia affinis/dubia. D.
pulex was the test species of choice because it
exhibited a greater degree of sensitivity in the first
round of testing. The second round of testing
confirmed the acute toxicity in the effluent from
outfall 003.
Characterization of the Eff luent
Enviro-Systems, another TI consultant, and TI's
MAPA Lab carried out similar analysis of the
effluent based on EPA's guidelines. Metals were
suspected to be a cause of toxicity in the effluent, and
a correlation between metals and toxicity was
established. Analyses for metals were conducted
using Atomic Absorption Spectrometry and
Spectrophotometry, and using inductivity coupled
A-33
-------
Outfall Location
Figure A6-1. Texas Instruments Attleboro outfall locations.
Table A6-1. Range of Daphnia pulex LCSO's and NOAEL*
Sample Location
a. Outfall 003
b. Outfall 005
c. Cooling Tower Slowdown
d. Unnamed Brood down-stream
Range of
LCSO's
(% Effluent)
0.1-2.5
35
41
1 .69-5
Range of
NOAEL
(% Effluent)
0.1-1
25
i
1.1-1
of outfall 003 and 004
discharge
e. Coopers Pond Influent
f. Coopers Pond Outfall under
railroad embankment
1.91
1 .55-1 00
1
1 .0-100
* Table taken from Veale and Elliot (1987)
plasma spectrometry. The team correlated the
concentration of various parameters to acute LCgo,
acute NOAEL, and chronic NOAEL. In order to
illustrate this correlation, acute bioassays were
conducted using D. pulex and chronic bioassays were
conducted using C. affinisldubia under stable
laboratory conditions. Five sets of effluent samples
were analyzed to determine acute LC$o, acute
NOAEL and chronic NOAEL and the corresponding
metal concentrations in each of the five sets were
determined. Results from these tests are summarized
in Table A6-2.
The 48 hr. LCso values for D. pulex ranged from 73.29
percent to 100 percent, while acute NOAELs ranged
from 50 percent to 100 percent. The results of the
chronic toxicity studies revealed no effect from the
effluent on production of neonates by adult
Ceriodaphnia (which survive the test), at
A-34
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Table A6-2. Summary of Results From Representative Acute and
Toxicity Reduction Evaluation, August 1985
Chronic Effluent Toxicity Tests, Texas Instruments
Test Series
Parameter
Acute LC50"*
Acute NOAEL"
Chronic NOAEL""
Hardness (mg/L)
Alkalinity (mg/L)
Ammonia (mg/L)
Residual Cl (mg/L)
pH (S.U.)
Ag (mg/L)
Al (mg/L)
Cd (mg/L)
Cr (total) (mg/L)
Cu (mg/L)
Fe (mg/L)
Ni (mg/L)
Pb (mg/L)
Se (mg/L)
Sn (mg/L)
Zn (mg/L)
Cr ( + 6) (mg/L)
CN (mg/L)
F (mg/L)
P (mg/L)
Pd (mg/L)
B (mg/L)
" Table taken from Veale and
** Acute test species was
*** Chronic test species was
1
100%
100%
12. 5%
76
81
0.01
0
7.66
0.005
0.52
0.004
0.0005
0.009
0.064
0.12
0.001
.01
0.01
0.008
0.0005
0.06
4.7
0.69
0.005
0.6
Elliot (1987)
Daphnia pu/ex
Ceriodaphnia
II
73.29%
60%
6.25%
0
73
0.02
0
1 1.12
0.068
0.12
0.006
0.020
0.046
0.098
0.25
0.001
0.01
0.01
0.013
0.020
0.07
5.4
1.2
0.005
0.58
affinisldubia
III
100%
50%
20%
48
56
0.01
0
7.80
0.025
0.52
0.006
0.035
0.041
0.23
0.20
0.043
0.01
0.045
0.028
0.035
0.21
1.8
1.8
0.005
0.5
IV
100%
100%
60%
51
71
0.7
0
7.94
0.0008
0.71
0.002
0.0005
0.014
0.29
0.12
0.002
0.01
0.01
0.004
0.0005
0.09
I.I
I.I
0.005
0.5
V
100%
100%
80%
66
74
0.9
Q
7.70
0.0005
0.32
0.008
0.0005
0.005
0.055
0.09
0.023
0.01
0.01
0.005
0.0005
0.06
I.I
0.48
0.005
0.27
concentrations from 6.25 to 80 percent effluent. No
direct correlation between any single compound and
effluent toxicity could be found. However, when
silver, copper and lead levels were simultaneously
low, there was a correlating reduction in toxicity
even when the levels of other metals were high.
Toxicity Reduction Approaches
To reach the goal of no toxic materials in toxic
amounts, TI elected to evaluate advanced treatment
technologies to determine if acceptable effluent
quality could be attained. Selected state-of-the-art
technologies which were tested included the
following:
Insoluble (iron) sulfide precipitation process.
Membrane microfiltration.
Chelating resin ion exchange.
Soluble (sodium) sulfide precipitation and
filtration.
The treatment evaluation program required several
months of data collection, from June through
October, 1985. As noted previously, effluent samples
from each pilot unit were subjected to toxicity testing,
in addition to analyses, for the constituents listed in
A-35
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the new discharge permit. This in-depth testing, data
collection and data analyses eventually determined:
The feasibility of advanced treatment to produce
an effluent meeting the TRE objective.
Estimations of full-scale chemical consumption
rates and chemical costs.
Operational and maintenance advantages and
disadvantages of each process.
Process turndown capabilities and operational
flexibility.
Full-scale design parameters.
For this specific project, the pilot testing favored the
selection of the insoluble sulfide precipitation process
for advanced treatment and polishing of the effluent
from TI's existing hydroxide precipitation treatment
system.
Pilot Testing
In order to establish baseline toxicity, design and
operating data for the advanced treatment processes
required to meet TI's new permit limits, a
comprehensive pilot testing program was developed.
During this pilot testing program, a series of acute
and chronic toxicity tests were conducted using
treated effluent from the pilot units.
Conclusions, Comments, and
Recommendations
In May 1985, TI contracted with United Engineers
and Constructors Inc. (UE&C) of Boston for the
design upgrade of the existing industrial wastewater
treatment system for their Attleboro facility.
Improvements to the existing wastewater treatment
system were to include advanced treatment
technologies.
UE&C developed a cost-effective application of an
Insoluble Sulfide Precipitation Process during the
pilot studies. This method was successful in meeting
the discharge limits and the toxicity requirements in
the NPDES permit. This new unit has not yet been
put into normal operation at the TI plant.
References
Bazza, R.V., C.M. Kelleeher, and M. B. Yeligar.
"Metal and Finishing Wastewater Treatment
Upgrade with Insoluble Sulfide Precipitation
Process," Paper presented at Eighth Conference
Pollution Control for the Metal Finishing
Industry, San Diego, CA, Feb. 9-11,1987.
Veale, F.I., and M. J. Elliot. "Meeting the Water
Quality Criteria for the Metal Finishing
Industries." Environmental Progress, 6(2), May
1987.
A-36
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Section A-7
Case History: Chemical Plant I
Introduction
This case study presents information and data
gathered during a toxicity reduction evaluation
conducted in 1985 and 1986. The facility under study
is located in an eastern coastal state with discharge
to the Atlantic Ocean. The investigation was
performed by AWARE Incorporated. A permit
effective July 1, 1985 required the plant to conduct
toxicity tests on Mysidopsis bahia, a saltwater
shrimp, to comply with a 96 hr LCso value > 50
percent effluent toxicity limit. This permit
requirement was to be attained in no more than three
years from the effective date of the permit, with
interim improvement levels specified as well. The
permit also required that the TRE identify
technologies capable of attaining the interim and
final toxicity limits within one year (July 1986).
Quarterly reports on the technological progress to
reduce toxicity were also required.
Initial Data and Information Acquisition
Products manufactured at the facility included
organic dyes and intermediates, epoxy resins, and
fine chemicals used for textile, paper and plastic
industries. Figures A7-1 shows a process flow
diagram for the waste treatment system. As of June
1985, the biologically treated wastewater at the plant
was highly toxic to M. bahia (LCso = 5 percent).
Toxicity Identification Evaluation (TIE)
Toxicity Screening
Ammonia
Ammonia was suspected as a causative agent due to
levels of 20 to 30 mg/L in the treated effluent.
Ammonia stripping was tested to determine if
ammonia could be the major cause of the toxicity.
Biodegradability
Extended aeration biodegradation testing was
performed with a seven day retention time following
activated sludge treatment. A non-biodegradable
fraction of 70 mg/L remained and no significant
reduction in toxicity was observed. However, this
method succeeded in removing the chloro-compounds
revealed during the GC/MS analysis.
Priority Pollutants
Methylene chloride and methyl isobutylketone were
used in extraction tests to determine whether organic
priority pollutants in the effluent were causing the
toxicity. Both tests failed to achieve the objective of
eliminating toxicity.
Metals
In order to determine the role metals were playing in
the effluent toxicity, precipitation/filtration tests
were performed using sulfide, hydroxide, and alum.
Metals removal resulted in insignificant toxicity
reduction.
Non-biodegradable/non-polar Organics
In order to determine the significance of non-
biodegradable, non-polar organics, the biologically
treated effluent was exposed to further, complete
biological treatment followed by contacting with
pulverized activated carbon. This resulted in nearly
complete removal of TOC and toxicity.
GC/MS Analysis
GC/MS analysis revealed that benzanthracene, a
large multiple-ring aromatic compound was the most
probable potential toxicant. However, there was no
known source of the compound within the plant. This
compound was detected in the final effluent sample
which had the lowest LCso value. Other potentially
toxic compounds which were occasionally detected
included chloroform, tetrachloroethylene, 1,1,1-
trichloroethane, napthalene, dibutylphthalate and
azo compounds. However, all of these compounds
were found in both non-toxic and toxic samples in
similar concentrations.
Toxicity Characterization and Source
Went/ficat/o/i
A preliminary screening program investigated
sources of toxicity from seven areas in the plant.
A-37
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Equalization
Basins
Neutralization Clarifier Aeration Secondary
Basin Clarifier
Lime
Gravity
Thickener
Aerobic
Digester
Gravity Sludge
Thickener Holding
Filter
Press
Figure A7-1. Waste treatment plant process flow diagram.
Relative toxicity of suspected organic and inorganic
compounds were determined and an initial data base
on end-of-pipe toxicity reduction was developed.
Samples of the effluents from each of the seven
production units were collected and analyzed before
and after passing through the existing treatment
system in order to determine the relative toxicity of
suspected organic and inorganic compounds. Based
on 48 hour LCso tests, it was observed that the
effluent from every production unit was toxic because
the sample failed to produce an LCso value > 50
percent for the effluent when diluted to the level
found in the discharge.
evaluation, wastestreams were placed into one of four
separate wastestream classes, as described below.
Class A wastestreams are toxic and non-
biodegradable. These may require treatment at the
source to reduce toxicity. Class B wastestreams are
toxic and biodegradable, and can normally be treated
with conventional treatment processes. Class C
wastestreams are non-toxic, but may contribute to
final effluent toxicity through synergism and inplant
reaction. Class D wastestreams are non-toxic and are
unlikely to contribute to toxicity in the final
wastestream.
Source Classification
Studies were begun to classify and identify
wastewaters which proved toxic to M. bahia. This
study was aimed at identifying those wastestreams
which had the highest probability of causing toxicity
to M. bahia, after passing through the biological
treatment. The rate of biodegradation and biotoxicity
(to M. bahia) for each wastestream was determined
using the Fed Batch Reactor test method (Watkin
1986).
Classification of the wastestreams was done in terms
of relative biodegradation rates and potential for
causing toxicity to M. buhiu. Based upon the
Table A7-1 summarizes typical classification results
from the grading of the wastestreams for selected
wastestreams.
In total, 126 wastestreams were classified, of which
14 wastestreams fell in Category Class A, 24
wastestreams fell in Category Class B, 29
wastestreams fell in Category Class C, while 54
wastestreams were classified as Class D. Based upon
those results, source reduction or treatment projects
were defined for Class A and B streams (Table A7-2).
The results of these projects are summarized in a
later section.
A-38
-------
Table A7-1. Typical Classification Results of Wastewater Sources
Biological Treatability Bioassay Toxicity
Q Max 48 hr LC50a
(mg TOC/gm-hr) (TOC, mg/L)
Class A Wastestreams (nondegradable
with suspected toxicity)
A
B
C
D
Class B Wastestreams (biodegradable
with suspected toxicity)
E
F
G
H
<1
<1
<1
<1
22.4
30.0
7.9
5.5
<8
0.5
16
2.4
16
14
26
7.2
Maximum Plant
Loading6
(TOC, mg/L)
i
0.4
5.5
1.7
4
8
10
3.1
Class C Wastestreams (unlikely to induce
toxicity)
1
J
K
26.5
5.3
5.4
14.1
104
319
111
375
14
36
11.7
56
a Mysidopsis bahia
b Contribution of the source to the combined effluent expressed in mg source TOC per liter combined effluent.
Source of Toxicity
A distinct relationship existed between the total
organic carbon (TOC) and toxicity before and after
biological and carbon treatment. However, no
correlation was detected between the influent TOC
and the effluent toxicity level. Data strongly
indicated that non-biodegradable organic material
was the source of toxicity in the effluent.
Toxicity Reduction Approaches
Source Reduction
This program was aimed at eliminating or reducing
the discharge of raw materials, metals, inorganic and
organic compounds. Waste profiles were established
for each of the production units. This included process
water description sheets and material balance sheets
accounting for approximately 90 percent of
production volume. This proved to be an excellent
tool for wasteload reduction and process
improvement. The discharge of certain toxic
materials was reduced, if not eliminated, with the aid
of process modification. In addition, the following
treatment technologies were examined.
Metal Precipitation
Metal concentrations were significantly lowered in
some Wastestreams by carrying out metal
precipitation at the source.
Reverse Osmosis
This technology proved to be partially effective in
reducing toxicity and TOC in waste liquor discharged
Table A7-2. Treatability and Toxicity Factors from Identified Wastestreams
Production Units
A
B
C
D
E
F
G
Beodegradabiiity
Negligible
High
Negligible
Very High
High
High
Very High
Organic Removal
Low
Low
High
High
Very High
Very High
Very High
BOD Removal
Negligible
Moderate
Moderate
High
High
High
High
Responsible
Toxicants
Organic Compounds
Copper and
Chromium
Copper
A-39
-------
from some production units. However, there were
several drawbacks associated with reverse osmosis
technology. Some of the problems included disposal of
the concentrate, limitation of available membranes
and formation of a heavy, tarry material due to
caustic soda addition during neutralization.
Peroxide Treatment
This method gave mixed results. Although it needs to
be studied further, no attempt to investigate this
technology was made until November 1986.
Carbon Adsorption
Based on the identification of Class A streams in the
classification system described previously, carbon
pretreatment tests on Class A wastestreams were
completed by September 1985. Activated carbon
(adsorption) dosages as high as 200,000 mg/L were
required to reduce TOG to acceptable levels. The
carbon dosage required to obtain an LCso value of 50
percent or greater effluent in a batch reactor ranged
from 10,000 to 50,000 mg/L. Investigations were
performed on 12 Class A streams and significant
reduction in effluent toxicity by carbon contact was
observed.
Wet Air Oxidation
Wet air oxidation also was examined. Significant
reductions in toxicity improved biodegradability and
a 98 percent TOG removal were observed in some
waste streams. A 40 fold improvement in
biodegradability was observed in some cases.
Powdered Activated Carbon Treatment (PACT)
Based on bench, pilot and full scale end-of-pipe
treatment studies, it was determined that the PACT
technology was a technically and economically
feasible alternative. A carbon dosage of 100 mg/.L was
required (in the bench-scale units) to consistently
meet an interim toxicity requirement (LCso value S
20 percent effluent) while a dosage of 250 mg/L was
necessary to comply with the final toxicity
requirement (LCso value S 50 percent effluent).
Bench scale results also indicated that a carbon
dosage of up to 500 mg/L may be required under
certain extreme influent conditions.
Winter conditions did not significantly affect toxicity
reduction performance, but did decrease the organic
removal efficiency.
The effect of hydraulic retention time (HRT) did not
seem to impact treatment performance significantly.
The system was operated at HRT's of 2.1 days and 1.1
days during optimization studies to evaluate the
effect of operating only one of the two existing
aeration basins.
The investigation demonstrated the success of
flocculent addition to remove color, and the success of
PAG addition to remove metals, chromium in
particular.
The toxicity reduction potential of the system seemed
to be impaired when operated at solids retention
times of 15 days or less. Solids retention times (SRT)
of between 30 days and 50 days achieved optimum
toxicity reduction. Operating the system at an SRT
outside this range was found to increase effluent
toxicity. Addition of ferrous ion to the activated
sludge reactor was not found to reduce toxicity.
Regeneration of powdered activated carbon was not
found to be attractive due to loss of adsorptive
capacity and loss of carbon in the process. For
equivalent results approximately twice as much
regenerated carbon was required than virgin carbon,
Carbon losses of 20 to 25 percent were experienced in
the regeneration process under conditions required
for good quality carbon.
Granular Activated Carbon (GAC) Adsorption
Initially, carbon isotherms were constructed on four
alternate carbons: Calgon F-300, Calgon F-400, ICI
HD-3000 and ICI HD-4000. Calgon F-300 was
selected for the GAC column operation based upon
much superior toxicity reduction in the isotherm
testing.
Initial column studies (up to September 1985)
indicated that GAC was very effective in toxicity
reduction and in removing soluble organic
compounds from the wastewater, particularly the
high molecular weight and non-polar compounds.
Moderately high adsorption capacities were observed
from the operation of three GAC columns in series
utilizing an LCso of 50 percent as the breakthrough
criterion. Carbon usage rates were found to be within
acceptable ranges (1 gram carbon per 0.09 to 0.12 g
TOG removed). Thermal regeneration of Calgon F-
300 did not appreciably alter its effectiveness.
Ozonation
Ozonation of the secondary effluent was also studied
during the end-of-pipe treatment evaluation. It
initially demonstrated some effectiveness but
additional testing revealed that it was not as effective
in reducing toxicity as other methods examined.
Therefore, ozonation was abandoned as a feasible
treatment alternative.
Basis for Selection of Method
Based on success with bench, pilot and full-scale
studies, conversion of the existing biological system
A-40
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to PACT using virgin carbon was the system of
choice. The selection criteria of most significance
were in the cases of installation, performance
flexibility, and cost.
Follow-Up and Confirmation
Source reduction, source treatment and treatment
system optimization efforts were completed between
September 1984 and June 1986. The new treatment
modifications were designed by June 1986 and
installed by November 1986. Follow-up studies are
presently underway at the facility.
Problems Encountered
Although there appeared to be a relationship
between residual TOG and toxicity after biological
and carbon treatment, it was not consistent from day
to day. Some days an LCso of 50 percent appeared to
correspond to a TOG of 20mg/L. Other days, it might
be 10 mg/L or 40 mg/L.
During pilot plant studies for the PACT and
biological treatment systems it was observed (in
carbon regeneration) that the best condition for TOG
removal was found to be the worst for carbon losses.
Results of toxicity testing for 22 Class D streams
following biological treatment indicated that a
synergistic effect may have existed which resulted in
elevated toxicity.
Recommencfof/ons, Commenfs and
Conclusions
As a result of conducting the TRE, the TOG loading
in the treatment plant discharge was reduced by 23
percent in 1985 as compared to 1984. This was
largely due to source treatment methods, process
modifications, wastestream treatment, and improved
housekeeping. By 1985, as many as 27 Class A
streams were treated, of which eight were treated at
the source; five were precipitated to eliminate copper
and chromium and 14 sulfide containing streams
were air oxidized to generate a less toxic effluent. The
discharge in six wastestreams was entirely
eliminated during the same time.
A PACT system with a carbon dose of 250 mg/L would
enable the company to comply with all discharge
criteria.
The final results of the TRE indicated that if wet air
regeneration of powdered carbon was used, the
dosage could well increase to as much as double the
virgin dose. Although ash accumulation is associated
with it, it is believed it would be manageable, but
carbon loss would be excessive.
Reference
Watkin, A. Evaluation of Biological Rate Parameters
and Inhibitory Effects in Activated Sludge. Ph.D.
Thesis, Vanderbilt University (1986).
A-41
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Section A-8
Case History: Chemical Plant II
Introduction
Treatment alternatives to reduce the effluent toxicity
of a chemical manufacturing plant were investigated.
The facility was issued a new wastewater discharge
permit which included an effluent toxicity limit
based on toxicity tests with Mysidopsis bahia
(mysids). An end-of-pipe 96 hour LCso value of 50
percent to be achieved within 3 years, was required
by the compliance schedule specified in the permit.
Initial Data and Information Acquisition
The chemical manufacturing facility is involved in
the production of surfactants (alkylphenol, alcohol
ethoxylates) and their derivatives and intermediates,
and synthetic organic compounds such as aromatic
hydrocarbon bases and tetrahydrofuran (THF).
Effluent from the plant's process wastewater was a
complex mixture, including "fresh water" discharges
from chemical reactors, storage tanks, tank wagons,
a drumming station, and equipment cleaning
operations; "saltwater" discharges from cooling
towers, fume scrubbing, and vacuum jets; and
sanitary wastewaters, surface runoff and
groundwater (carrying landfill leachate) also enter
the wastewater system. Figure A8-1 depicts the plant
wastestream schematic and the influent sources to it.
Plant or Process Description
The Waste Water Treatment Facility (WWTF)
consisted of coarse screening, oil skimming,
equalization, neutralization, activated sludge
treatment and chlorination (Figure A8-1). The
system was equipped with gravity thickening and
pressure filter dewatering to enhance sludge
handling.
Effluent Toxicity
The new permit required the WWTF to achieve an
end-of-pipe 96 hr, static, daily replacement LCso
value of 50 percent effluent based on toxicity tests
with M. bahia (mysid shrimp). Data indicated the
effluent 96 hr LCso was 3 percent. Influent toxicity
ranged from 2.1 to 3.1 percent.
Existing performance data was not conclusive on the
ability of the WWTF to reduce effluent toxicity.
Therefore a toxicity reduction evaluation was
conducted in three steps. System upgrade was
required to comply with the new permit limits.
Evaluation of Treatment Process Optimization
Step one included the preliminary investigation and
was aimed at assessing the feasibility of using the
activated sludge process to reduce the toxicity of the
effluent. Operating procedures, reseeding, ultimate
toxicity reduction potential, and influent wastewater
characterization were all examined.
The preliminary investigation indicated that at
laboratory-scale, activated sludge system
significantly reduced the effluent toxicity to M.
buhiu. Effluent from two reactors (one seeded with
municipal seed and the other seeded with industrial
seeds) were tested. The source of the seed in the
municipal sludge reactor was from a local POTW.
The source of the seed in the industrial sludge reactor
was from a sister-facility in another state. The period
of acclimatization for the seed ranged from 4 to 8
weeks.
Results of these tests indicated that the reactor
seeded with municipal sludge was in compliance with
the toxicity limit (50 percent effluent LC$Q value)
half the time, while the reactor seeded with
industrial sludge did so only 25 percent of the time,
Variation was attributed to operational parameters
of the reactor and not the seed characteristics.
Unsynchronized operation of the reactors, different
feed characteristics, and higher effluent TSS were
among the factors responsible for these variations.
Attributes of the two reactors are summarized in
Table AS-1. The average BODs removal efficiency for
the reactor seeded with municipal sludge was 88
percent while that seeded with industrial sludge was
83 percent. The unit seeded with municipal sludge
exhibited 56 percent TOG removal efficiency,
A-43
-------
Influent
Waste
Water
Polymer
Legend
-Forward Flow
Sludge Flow
-Secondary Flow
Sludge
Dewatering
System
MC
Chlorine
hlorination r-^ Effluent
, Solid Cake
to Disposal
Figure A8-1. Wastewater flow and treatment schematic.
whereas the TOG removal efficiency for the unit
seeded with industrial sludge was 51 percent.
Table A8-1. Comparison of Reactor Performance
Municipal Industrial
Sludge Sludge
Reactor Reactor
BOD5 Removal Efficiency
TOC Removal Efficiency
Stable Mixed Liquor Volatile Suspended
Solids
Zone Settling Velocity
Oxygen Uptake Rates
88% 83%
56% 51%
2000 2000
mg/L mg/L
nftfhr isftfhr
15 mo/hr 15 mo/hr
Both the reactors exhibited stable mixed liquor
volatile suspended solids at a design concentration of
about 2000 mg/L with consistently good sludge
settling characteristics. The zone settling velocity for
the municipal sludge reactor was 11 ft/hr while that
for the industrial sludge reactor was 15 ft/hr.
Consistent oxygen uptake rates (approximately 15
mg/hr) were observed for both the reactors.
From bench scale results it was concluded that plant
optimization may result in near compliance with
toxicity requirements. Based upon this, all efforts
were directed towards making necessary
improvements to the treatment plant and confirming
the bench scale results in a pilot scale system.
Unfortunately, the pilot scale results deteriorated
over a three month period with no apparent change in
conventional parameters.
Toxicity Identification Evaluation (TIE)
The second step of the TRE was aimed at identifying
the specific causes for effluent toxicity, investigating
the effectiveness of end-of-pipe treatment
alternatives, testing certain plant product groups for
their biodegradability/toxicity reduction, and
observing the effectiveness of several physical-
chemical processes to treat the plant's products. It
included onsite, pilot plant investigations during
which the activated sludge process was tested under a
range of organic loadings and hydraulic retention
times.
Laboratory tests were conducted to determine
whether the activated sludge process could be used to
reduce toxicity in segregated (concentrated) process
wastewaters without inclusion of cooling waters,
boiler blowdowns or surface runoff. A secondary
objective of this investigation was to assess the
impact of "rare" wastewater discharges on the
performance of the activated sludge process.
Causative Agent Identification
During the second and third steps of the study, the
identification of effluent components responsible for
the toxicity of the wastestream was investigated.
Mysid toxicity tests were conducted with pilot plant
reactors continuously fed from the equalization basin
effluent. The results did not indicate any correlation
between the plant production profile and effluent
values.
Results of paired LCsp tests indicated that toxicity
increased with organic loading and the lowering of
operating temperature. Filtered effluent samples
were less toxic than those of the corresponding
unfiltered samples. Analysis of the effluent using
HPLC technology showed a positive correlation
between effluent toxicity and nonylphenol (NP)
concentration in the effluent.
A-44
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Continuous flow reactors were fed with aliphatic
based compounds. Reactors #1 and #3 had TOG
removal efficiencies of 89 percent and 86 percent
respectively. Reactors #2, #4, and #5, which were
fed with aromatic based products achieved
approximately 80 percent TOG removal efficiency.
However, reactor #6, which was fed with linear
nonylphenol ethoxylate (NPEO) had TOG removal
efficiency of only 74 percent. The results indicated
that reactors fed with NP exhibited higher toxicity
based on TOC removal than other reactors.
A comprehensive analysis of the TOC, NP and NPEO
and ammonium (NH4-N) concentrations in the
effluent was then conducted. It established a
correlation between the LCso and effluent
concentrations of NP and NPEO.
Batch test results from the end-of-pipe investigations
also established a positive correlation between NPEO
concentrations and effluent toxicity. An LCso value
of 100 percent effluent could be reached at
concentrations of NPEO below 0.07 mg/L. Even
though NPEOs may not have been the sole cause of
toxicity in the effluent, they were a good indicator of
the presence of a larger class of toxic constituents.
Confirmation of Source or Agent
End-of-pipe and at-source treatment investigations
concluded that NPEO was the principle toxic
component in the WWTF effluent samples.
Treatability Evaluations
The last step of the toxicity reduction evaluation was
carried out to test the effectiveness of proposed source
and end-of-pipe treatment systems at both bench- and
pilot-scale. It was aimed at screening the at-source
and end-of-pipe treatment options. It included several
additional tasks which were aimed at evaluating
specific causes of effluent toxicity.
Based on the results of the plant studies during Steps
II and III, it was determined that effluent from the
existing biological treatment unit could not meet the
levels proposed by the new permit. To comply with a
whole effluent toxicity limit of an LCso 2: 50 percent
effluent, at-source treatment and end-of-pipe
treatment options were identified. These are
described below.
Source Treatment
This was a technically and an economically feasible
alternative. It involved separation of highly
concentrated, low-flow process wastewaters from the
non-contact cooling water and some lightly
contaminated flows (fume scrubbings, vacuum jet
streams, etc.). Following pretreatment, the
wastewater was combined with other plant flows for
conventional treatment prior to discharge.
Seven individual products of the company were batch
treated with activated carbon, activated alumina,
alum, Fuller's Earth and ion exchange resin.
Activated carbon was identified as a feasible
alternative as it consistently eliminated 90 percent of
the seven products tested. The other treatment
methods failed to demonstrate consistency in
reducing toxicity.
End-of-Pipe Treatment
Various tertiary treatment processes were evaluated
which included adsorption using selective agents
(activated carbon, Fuller's Earth, activated alumina
and ion exchange resin), alum treatment, and
chemical oxidation using hydrogen peroxide. The
feasibility of operating the Powdered Activated
Carbon Treatment (PACT) and Granular Activated
Carbon (GAG) treatments were also assessed. The
PACT treatment was very efficient (approximately
100 percent removal) in removing the NPEO at
dosages of 200 mg/L. Treatment with alum, activated
alumina and ion exchange resin resulted in NPEO
removal just over 50% at dosages of 200 mg/L.
Activated carbon treatment was determined most
effective based upon removal of the toxicity causing
agents. The cost of both the PACT and GAG
technologies were similar. However, the PACT
process did not require facility modification while the
GAG treatment process required another facility for
its operations. End-of-pipe treatment with alum was
not seriously considered because of the limited data
available on its capabilities.
Final Comments, Recommendations and
Conclusions
This TRE proved to be of great benefit in identifying
the cause of the effluent toxicity. The TRE also
helped identify the feasible treatment alternatives.
The end-of-pipe PACT treatment system was a viable
alternative because it achieved effluent LCgo values
of a 50 percent effluent as required by the permit,
and could be implemented without facility
modification.
The biological source treatment was another
attractive option which appeared technically and
economically feasible. End-of-pipe alum treatment
and the use of GAG (following biological treatment)
were not viable processes to introduce due to limited
data and high capital and operating costs.
Pilot plant (activated sludge) studies indicated that
addition of polymer to the wastestream was effective
in controlling effluent suspended solids. The BODs
A-45
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and the TOG in each of the 6 reactors were in
compliance with the new permit limits. The
concentrations of phenol, surfactants (MBAS), oil and
grease also achieved permit limits.
A-46
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Section A-9
Case History: TRE of I.T.T. Effluent
Introduction
The following is a description of the toxicity
reduction evaluation (TRE) conducted at the I.T.T.
Rayonier plant (Mount and Anderson-Carnahan,
1986). I.T.T. Rayonier, Inc., located on the Amelia
River at Fernandina Beach, is one of Florida's major
industrial facilities. Figure A9-1 presents a
schematic diagram of the processes in the I.T.T.
Rayonier wastewater treatment system. In order to
resolve outstanding NPDES permit issues associated
with I.T.T.'s effluent discharge, and to implement a
site-specific application of EPA's "Policy for the
Development of Water Quality-based Permit
Limitations for Toxic Pollutants", a number of issues
were studied at the I.T.T. plant. Toxicity
identification and reduction was an important
segment of the study.
Initial Data and Information Acquisition
Plant Description
The I.T.T. plant manufactures chemical cellulose
(pulp) from Southern pine by the sulfite process.
Effluent control consists of red liquor evaporation
and burning, primary, and secondary treatment
(standard in the industry).
Characteristics of Effluent
Wastewater characteristics of the treated effluent
during May 14-21,1986 are presented in Table A9-1.
Toxicity Identification Evaluation (TIE)
A preliminary effluent characterization was
performed with effluent samples collected during
July 1985 and March 1986. An on-site study of the
effluent using two mobile toxicity test laboratories
was performed during May 13-26, 1986.
Data Collection and Methods
For the on-site study, grab and 24-hour time
composited samples were collected from the aeration
lagoon near the point of discharge. Table A9-2 shows
a listing of the samples. These samples were coded
according to the date of collection (month/day) and
the number of the sample collected that day (I, II,
III,..). Phased testing was conducted with the
collected effluent.
The physical and chemical properties of the effluent
toxicant(s) were first isolated and characterized
using a parallel series of tests. Each test was
designed to remove or render biologically unavailable
a specific group of toxicants, such as oxidants,
organics, metals, etc. Timed lethality tests using
Ceriodaphnia were performed before and after the
test treatment to indicate the effectiveness of the test,
and hence the nature of the toxicant(s). A series of
blanks and controls were used with each test to
insure that no toxic artifacts had been created during
sample manipulation. The variability of the
compounds causing toxicity was assessed by
repeating the toxicity characterization test series
using samples collected over a period of time. Both
the 48-hour LCso value and average time it took to
cause 50 percent lethality in Cerioduphnia were used
to measure the relative toxicity of the baseline
effluent. Other tests employed only timed lethality
tests to assess the change in toxicity. Five toxicant
characterization tests were used in parallel during
the study.
Filtration - This procedure is used to indicate
whether toxicants were associated with filterable
materials. Also, since the filtered effluent was used
in another characterization test, it was necessary to
assess the effect of filtration on effluent toxicity.
Air-stripping - This is used to characterize the
volatility and oxidizability of causative toxicants. By
adjusting the pH of the effluent prior to stripping, the
acidic or basic nature of the toxic compounds can also
be assessed.
EDTA chelation - By adding increasing doses of
EDTA to aliquots of effluent, toxic cationic elements,
like lead, copper, cadmium, nickel, zinc, etc. are
complexed with an organic ligand to produce a
nontoxic form of the cation. The time to mortality
should increase as the EDTA dose increases
(provided that toxic levels of EDTA are avoided).
A-47
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Wastewater f
bleaching
screening of
storm wa'
k.
Evaporation
k.
Grit Removal
k.
rom digesters,
washing,
Dulp (including
er runoff)
Sedimer
Chemical
Conditioning
Pressure
Filtration
Neutralization
Aeration
1
001 Effluent
to Amelia
River
T
Sludge to
Landfill
Figure A9-1. A schematic diagram of the processes in the I.T.T. Rayonier wastewater treatment system.
Table A9-1. Additional Wastewater Characteristics
During May 14-21, 1988
Effluent Characteristics Average Value
Range
Dissolved Oxygen (mg/L) 0.80 0.5-I .2
pH (Std. Units) 7.6 7.5-7.6
Alkalinity (mg/L) 269 218-334
Hardness (mg/L) 648 540-746
Conductivity (umhos) 2616 1674-3165
Table A9-2. Description of I.T.T. Rayonier On-Site
Samples3
Sample
(month/date/code)
Description
5/14/1
5/15/1
5/15/11
5/16/1
5/16/111
5/17/1
5/16/11
5/18/1
5/18/11
5/18/HI
5/18/IIIA
5/18/IIIB
5/18/IIIC
5/18/IIID
Composite Sample" 5/13 - 5/14/86
Composite Sample 5/14/86-5/15/86
Grab Sample 5/15/86-4:30 pm
Composite Sample 5/15-5/16/86
5/16/1 Composite spiked with NH4SO4
(as 100 mg/LNH4)
Composite Sample 5/16-5/17/86
Grab Sample 5/17/86 9:00 am
Composite Sample 5/17-5/18/86
Grab Sample 5/18/86 9:30 am
Grab Sample 5/18/86-12:30 pm
5/18/III Sample spiked with NH4SO4 (as
100 mg/LNH4)
5/18/111 Sample raised to pHll, aerated
for 2.25 hours and returned at pH 7.5
5/18/HI Grab Sample (unaltered)
5/18/HI Sample spiked with NH4S04 (as
100 rno/LNH^ and aerated
a All samples collected in the aeration lagoon near the point of
discharge.
b 24 hour composite sampling from 9:00 am to 9:00 am.
Oxidcmt reduction - This is similar to the EDTA test,
except that EDTA is replaced by sodium thiosulfate
(a reducing agent) The test indicates whether toxic
levels of inorganic oxidants such as chlorine,
chloramines, or electrophilic organics are present.
solid phase extraction - This column removes
nonpolar organics and chelated metal complexes
from the effluent. By adjusting the pH of the
effluent, information on the acidity or basicity of the
causative toxicants can also be gained.
Other Toxicity Tests
Short-term chronic toxicity tests were performed
using Ceriodaphnia reticulata and Pimephales
promelas (fathead minnow). Acute and chronic
toxicity tests were conducted with the marine
organisms Arbacia punctulata (sea urchin), Champia
parvula (red algae), Mysidopsis bahia (mysid
shrimp), Menidia beryllina (silverside minnow), and
Cyprinodon uariegatus (sheep shead minnow). The
recently developed Lemna minor (duckweed) chronic
toxicity test was also used. The Cerioduphnia species
was chosen for the timed lethality tests because of its
sensitivity and convenience of use.
Effbent Toxicity
Prior to the May 1986 on-site study, several samples
of I.T.T. effluent were subjected to a preliminary
analysis. The first sample (July 1985) produced rapid
lethality to Cerioduphnia. Subsequent charac-
terization tests indicated that toxicity could be
reduced by adding EDTA. Chemical analysis data for
the effluent sample were compared to metal toxicity
data from the literature. Copper and zinc appeared to
be the toxic agents in this sample. This sample also
had a very high level of suspended solids. This
A-48
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sample was considered by I.T.T. to be very atypical of
their effluent.
To confirm these early results and to assess toxicant
variability, a second sample of I.T.T. effluent was
collected in March 1986. This sample appeared to be
lower in suspended solids, zinc, and lead, and had an
acute toxicity that was much lower than the July
1985 sample. EDTA addition did not affect the acute
toxicity. The acceptable effluent concentration of the
sample in a chronic Cerioduphnia test was between 6
(NOEC) and 12 (LOEC) percent.
Previous effluent studies by the I.T.T. staff indicated
a potential for ammonia toxicity. Hence, this
possibility was investigated for the March 1986
effluent. When the effluent pH was raised (effectively
increasing the concentration of the toxic un-ionized
form of total ammonia), it was found that the acute
toxicity of the sample to Cerioduphnia increased.
Lowering the pH prevented acute toxicity in
Ceriodaphnia. Similar additions of acid and base to
control water did not cause lethality in Cerioduphnia.
However, when control water was spiked with
ammonia at concentrations equivalent to the
effluent, organism lethality occurred at similar times
to the effluent at the same pH.
Characterization and Fractionation
Because of the apparent difference in causative
toxicants in the two preliminary samples (metals
versus ammonia), a more in-depth characterization
study using a number of samples collected over a
period of time was conducted (May 13-26, 1986). A
Phase I battery of tests was run on the samples.
Except for the air-stripping test, the toxicity of the
5/13/1 effluent remained essentially unchanged.
Raising the pH of the effluent sample to 11,
moderately aerating for 255 minutes, and
readjusting it to the initial pH (7.4) prevented acute
toxicity in C. dubicz. Aeration in general appeared to
prolong the time to mortality in the neutral, and
acidified effluent samples. These results indicated
that the causative toxicant was volatile and basic in
nature. Ammonia (one of the production raw
materials) fits into this category.
The decision was made to focus subsequent
characterization tests primarily on ammonia (air
stripping and pH adjustment tests) and, to a lesser
extent, on metals (EDTA chelation test).
To further validate ammonia as the causative
toxicant, a series of samples were split for chemical
analysis and toxicity testing. EDTA addition to a
portion of the samples did not reduce toxicity. It was
also found that the sample toxicity decreased with
decreasing pH. Had cationic metals been the cause of
effluent toxicity, toxicity should have decreased with
decreased pH due to the increasing concentration of
biologically available metal cations. A chemical
analysis of the metal content of various samples
showed that the levels of copper, zinc, and lead in the
May 1986 samples were much lower than the July
1985 levels (when EDTA chelation decreased
toxicity, probably due to copper). Again, the data
indicated that ammonia was the primary toxicant.
Confirmation of Causative Agent
The main objective of this phase of the study was to
correlate effluent sample toxicity and the NH3
concentration (taking into account the differences in
effluent pH). In order to prove that such a correlation
exists, it is necessary that sample toxicity and NHs
concentration vary. To insure that there would be
some variability, several samples were spiked to
increase the range of NHs concentrations
encountered. One of these samples was also aerated
with the intent of reducing the concentration of
unionized ammonia. Following 2.25 hours of aeration
at a relatively constant pH of 11, the total ammonia
concentration was reduced from 90 to 67 mg/L as N.
The results of the toxicity tests and ammonia
analyses are presented in Table A9-3. The pHs of the
effluent sample/dilution water mixture producing the
lowest observed effect level (LOEL) and no observed
effect level (NOEL) were recorded at 24 and 48 hours.
The initial pH of the solutions drifted from 7.2 - 7.4 to
slightly higher values with time. The final pH values
for each solution were used in the calculations for
unionized ammonia concentrations. In most
instances, the pH of the solution producing the LOEL
was 0.05 units higher than the pH of the solution
producing the NOEL. This information was used to
estimate the pH in several LOEL mixtures.
In order to calculate the unionized ammonia
concentration in the effluent mixture producing the
sample LCso, the concentration of unionized
ammonia producing LOEL and NOEL was first
calculated using the pH and total ammonia
concentration in each and a test temperature of 25°C.
For the purpose of mass balance, it was assumed that
the dilution water had a negligible concentration of
total ammonia. Graphing the results and using
linear extrapolation, the approximate pH and
concentration of unionized ammonia in the effluent
mixture producing an LCso was determined.
A plot of the sample LCso (as % effluent) versus the
NHs concentration in effluent sample/dilution water
mixture producing the LCso yielded a significant
regression at P < 0.01. Thus effluent toxicity
correlated with NHs concentration.
The effect of pH and temperature, both on the percent
of total ammonia present in the unionized form and
on the toxicity of the unionized form, must
A-49
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Table A9-3. Toxicity and Ammonia for I.T.T. Rayonier Effluent Samples
Sample" (%
5/14/1
5/15/1
5/15/11
5/16/1
5/16/11
5/16/111
5/17/1
5/17/11
5/18/1
5/18/11
5/18/IIIA
5/18/IIIB
5/18/IIIC
5/18/11 ID
Total Ammonia 100'
LC50 Effluent
Effluent) mg/L
56
32
39
41
58
la
53
58
61
53
35
43
38
35
62
72c
80
76
79
120
92C
89
104
94<=
144
67
90
156
%
Pi
LOEL
7.9
7.7
7.65
7.8
7.85
7.8
7.85
7.85
7.35
7.7
7.55
7.65
7.55
7.6
Rb NH3-N(mg/L)
NOEL
7.85
7.65
7.65
7.8
7.75
7.75
7.8
7.8
7.55
7.65
7.55
7.65
7.6
7.5
LOEL
2.68
1.0
0.99
1.31
2.28
1.04
2.67
2.59
0.98
1.95
1.43
0.84
0.89
1.72
NOEL
1.20
0.45
0.5
0.66
1.25
0.47
1.59
1.56
1.03
1.13
0.71
0.40
0.51
0.69
NH3Conc. in
Effluent/Dilution
Water Mixture
Producing LC60
1.35
0.62
0.78
1.08
1.68
0.69
1.73
1.59
1.0
1.26
1.02
0.73
0.72
1.08
a for a description of the sample and sample code, see Table A9-2.
bpH of effluent/dilution water mixture producing the LOEL and NOEL was recorded at 24 or 48 hours, depending on when
organism mortality occurred.
c Estimated based on the pH data from other effluent/dilution water mixtures producing the LOEL.
be recognized. This information was pivotal in
correlating the concentration of ammonia in samples
with their LCgoS and also allowed testing equitoxic
concentrations of NH3 at different pHs in the effluent
and spiked control water. For additional information
on this subject, the reader is referred to EPA's report
ITT Rayonier Toxicity Reduction Evaluation (Mount
and Anderson-Carnahan 1986) and to EPAs TIE
Phase I Document (U.S. EPA 1988).
A final sample of the I.T.T. effluent was taken in
June 1986 for use in a pH adjustment test. The total
ammonia concentration in the June 1986 effluent
sample was 83 mg/L. Control water was spiked with
NH4C1 to produce a solution with 80 mg/LNHs.
Aliquots of the effluent and of control water were
adjusted to pH 7.5, 8.0, and 8.5. The symptoms
exhibited by the test organisms (Ceriodaphnia)
during the first six hours (the time during which an
equally toxic concentration of NHs was present in
each sample, and before pH started drifting) gave
strong evidence of ammonia toxicity.
The effect of the I.T.T. effluent on Champia parvula
reproduction (as measured by the number of
cystocarps produced) is shown in Figure A9-2. Also
plotted is the effect of NH4C1 on C. parvula
reproduction. As the effluent and NHijCl solutions
are diluted with control water, the effect is nearly
identical. The similarity of the two curves is
significant for ammonia as the likely causative
toxicant.
A comparison of the I.T.T. effluent toxicity data for
three marine species (C. parvula, M. bahia, and
Menidia beryllina) and the fathead minnow, with
ammonia toxicity data in the literature at
corresponding pH and temperature values was also
conducted. The I.T.T. effluent NHa toxicity data fell
within the range of NHs sensitivity values in the
literature.
The case for confirmation of ammonia as the cause of
effluent toxicity is thus based on four areas of
evidence.
(1) The effect of pH on the toxicity of the effluent.
(2) Symptoms exhibited by test organisms exposed to
the effluent and to standard ammonia solutions.
(3) The relative sensitivity of four aquatic species to
ammonia.
(4) Good agreement with ammonia toxicity data in
the literature.
Also, causative toxicant tests for cationic metals,
electrophiles, neutral and acidic volatile compounds,
adsorbed toxicants, nonpolar organics, and metal
chelates failed to indicate alternate sources of
toxicity. The toxicity of the atypical July 1985
sample, however, was obviously not caused by
ammonia.
A-50
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120
4 Effluent Dilution
0 NH4CI
Figure A9-2.Number ot cystocarps tor Champia parvula (as
% ot control) plotted against % ettluent.
Note: The effluent data are averages from May 17 and 18.
The ammonia chloride data are based on 70 mg NH,
N/L in the effluent. A stock solution of 26.7 mg
NH4CI/100 ml was used.
Toxicity Reduction Approaches
Treatability Evaluation
The TRE study conducted during May, 1986
suggested strongly that ammonia was the major
chemical causing toxicity in the wastewater.
Removal of ammonia may be achieved by chemical,
physical or biological methods. Some commonly used
ammonia removal processes are presented in this
section. Each technique is briefly described with
special features or requirements noted.
Air Stripping
Ammonia in water is in equilibrium with the
ammonium ion.
NH3 + H2O *5 NH4+ + OH-
When the pH is raised above 7, equilibrium shifts to
the left to form more unionized ammonia which may
be removed by agitating the aqueous sample in the
presence of air. In wastewater treatment practice,
ammonia removal is accomplished by increasing pH
to the range 9-11 and allowing wastewater to flow
through a packed tower equipped with an air blower.
As the temperature of the operation falls, more air is
required to strip ammonia. Cold temperatures can
also cause freezing and CaCOg scaling. For the I.T.T.
effluent, raising pH up to 11 and moderately aerating
for 255 minutes were effective in removing ammonia.
After stripping ammonia, pH can be readjusted to
desired levels.
Nitrification - Denitrification
Ammonia can be biologically oxidized to nitrite, and
then to nitrate by nitrifying bacteria under aerobic
conditions. Removal of the nitrates is accomplished
by treating wastewater with dentrifying bacteria
which reduce nitrate to nitrogen in an anaerobic
environment. The advantages associated with
nitrification - dentrification processes are (a) high
potential removal efficiency, (b) process stability and
reliability, (c) easy process control, and (d) moderate
cost. The optimum pH range for nitrification is from
8.2 to 8.6. For dentrification, the optimum pH is
between 6.5 and 7.5. Another significant factor in
this process is temperature. Effluent quality may
deteriorate at lower temperatures, though the solids
in the system could be increased to accommodate cold
temperature operation.
In addition to these processes, ammonia can also be
removed by electrochemical treatment, chlorination,
ion-exchange or bacterial assimilation. But these
latter options may not be suitable in this case.
Problems Encountered
One problem encountered was that in the small
volumes (5 ml aliquots) of effluents used for the tests,
many of the air stripping and pH adjustment tests
were frustrated by shifts in pH adjusted and
unadjusted samples exposed to air. Larger volumes
could not be used however, due to poor visibility in
the highly colored effluent. Because of this problem,
alternate strategies were also used to confirm the
extent of toxicity caused by ammonia. Since
invertebrates are generally more tolerant of un-
ionized ammonia than fish, toxicity tests were
performed using both C. dubia and Pimephales
promelas (fathead minnow). The 5/15/1 sample was
observably more toxic to the minnow as were control
water samples spiked at 100 and 200 mg/L as NH4+
(Ammonium Sulfate).
A-51
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References
Mount, D.I. and L. Anderson-Carnahan. "ITT
Rayonier Toxicity Reduction Evaluation." U.S.
Environmental Protection Agency Internal ORD
Report, October 1986.
U.S. Environmental Protection Agency. "Methods for
Aquatic Toxicity Identification Evaluations: Phase
I - Toxicity Characterization Procedures," Second
Draft dated June 1988.
A-52
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Section A-1 0
Case History: Monsanto Chemical Manufacturing Facility
Introduction
Monsanto's Environmental Science Center (ESC) has
developed, tested and refined a Toxicity
Identification Evaluation (TIE) protocol which has
been used successfully to identify toxic compounds in
several wastestreams (Doi and Grothe 1987). In
general the procedure uses both chemical (cation and
anion resins) and physical (helium sparging
filtration) separation to divide an effluent into
inorganic and organic fractions. The procedure is
followed by toxicity testing of each fraction in order to
identify and eventually abate the source of toxicity.
Once toxic constituents are known, remedial
activities can be planned.
Effluents from three chemical manufacturing plant
sites were used to evaluate the utility of the protocol.
Three effluents were selected based on the results of
acute toxicity tests conducted on Duphnia magna,
which indicated an ECso of less than 100 percent.
Each effluent came from an individual site (dubbed
sites 1,2, and 3 in this study).
Initial Data and Information Acquisition
Site I
The wastewater at this site was a relatively complex
mixture which contained a number of organic and
inorganic constituents. The team was also aware of
the fact that the wastewater had a relatively high
total ammonia content (100 - 300 mg/L). Although it
had been speculated that ammonia may be
responsible for the wastewater toxicity to D. magna,
earlier investigations failed to show that ammonia
was responsible for the toxicity of this wastewater.
Site 2
The wastestream at Site 2 was comprised of four
stormwater and/or cooling water inputs. The effluent
being investigated was known to contain hexavalent
chromium, chlorine, and biocide, which were used to
prevent corrosion and growth of algae and microbes
in the piping system.
Historical toxicity data collected in 1985 indicated
that the final effluent was toxic to D. magna. It was
speculated that hexavalent chromium could be
responsible for the effluent's toxicity since the
concentrations of hexavalent chromium in the
wastewater (100 - 200 ppb) were comparable to acute
effect levels (20 - 212 ppb) reported in the literature
for D. magna. No information was available on the
acute toxicity of the biocide.
Site 3
The effluent at Site No. 3 was a complex chemical
mixture containing a number of inorganic and
organic substances. Operation reports showed the
effluent to have a very high conductivity (10,000 to
25,000 micro mhos/cm). The existing levels of
calcium (300 mg/L), sodium (1020 mg/L) and chloride
(7310 mg/L) ions were associated with the high
conductivity.
Toxicity tests have been performed on the effluent
with the fathead minnow since the mid-1970's for
inhouse and regulatory compliance purposes. The
results of these tests indicated that the 96 hour LCso
was typically between 45 percent and 80 percent. The
toxicity of the effluent was speculated by a number of
investigators to be associated with the high salinity
of the wastewater.
Toxicity /den tifica tion Evaluation (77 E)
The main objective was to isolate and identify the
factors contributing to effluent toxicity. In order to
achieve this, ESC employed the testing scheme
illustrated in Figure A10-1 (based on concepts of
Walsh and Garnas (1983)) which utilized the ion-
exchange resin technology to fractionate the effluent
mixture into organic and inorganic constituents.
Once the effluent mixture was separated into
fractions, their potential toxicity was determined by
subjection to selected aquatic species. Additional
fractionation of the organic and inorganic
constituents would be necessary if either fraction was
found toxic to the test species.
Besides conducting toxicity tests on each of the
fractions, TOG (total organic carbon) and ICP
A-53
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Plant Water
ICP Analysis
TOC Analysis
Daphnia toxicity
ICP Analysis
Daphnia toxicity
TOC Analysis
ICP Analysis
Daphnia toxicity
TOC Analysis
ICP Analysis
TOC Analysis
Daphnia toxicity
ICP Analysis
TOC Analysis
Daphnia toxicity
ICP Analysis
Daphnia toxicity
TOC Analysis
ICP Analysis
Daphnia toxicity
TOC Analysis
Figure Al 0-1. ESC effluent fractionation and testing
scheme.
(inductively coupled plasma) measurements were
performed on the organic and inorganic fractions (see
Figure A10-1) to determine if a correlation existed
between toxicity and a specific chemical constituent.
Synthetic effluent (which contained a suspected
compound in control water at the same concentration
as in the natural effluent) tests were also performed
to gain additional insight about the source of toxicity.
Toxicity of the plant effluent was compared to the
synthetic effluent and in an event where toxicity
tests showed similar results, the suspected
compound(s) would be implicated as the source of the
toxicity.
Site J
The fractionation scheme utilized five treatments of
activated carbon, cation and/or anion exchange
resins and one treatment with zeolite (which is
composed of hydrous silicates). Site 1 effluent was
subjected to each of these separation processes, and
concurrent acute toxicity tests were conducted in
duplicate with each fraction using 100 ml of the test
solution and D. magna as the test species (ten first
instar daphnids), based on the guidelines
recommended by the U.S. EPA's Methods for Acute
Toxicity Tests with Aquatic Organisms.
Of the six treatments evaluated, only a sequential
treatment with activated carbon, cation and anion
exchange resins and zeolite was effective in
eliminating the toxicity of the effluent. All other
treatments had no effect in reducing effluent toxicity.
Examination of the TOC, ICP and ammonia analyses
indicated no apparent correlation between toxicity
and organic or inorganic constituents.
Because only limited information existed in the
literature regarding the acute toxicity of ammonia to
D. magna, the ESC team conducted toxicity tests
using ammonium chloride in a synthetic effluent. Six
effluent concentrations were tested using well water
(pH = 8.5; hardness = 160 mg/L) from eastern
Missouri as dilution water and a control. The 48 hr
ECso values and their 95% confidence limits for total
ammonia and un-ionized ammonia were found to be
32 mg/L (18.1 to 36.2 mg/L) and 0.35 mg/L (0.2 to 0.4
mg/L), respectively. Based on these acute effect levels
and the results of the toxicity tests with the effluent
and treatment fractions, the concentration of un-
ionized ammonia in the untreated effluent, activated
carbon, and anion treatments were determined to be
well above the acute effect concentration for
ammonia. However, un-ionized ammonia
concentrations in the cation resin treatments were
below the acute effect concentrations, even though
this treatment exhibited toxicity to D. magna.
On further investigation, it was found that when the
stock solution of 300 mg/L NH^Cl was passed
through the cation exchange resin, toxicity to D.
magna persisted even though ammonia levels were
reduced to < 1 mg/L. It was hypothesized that an
unknown toxic component was being released from
the resin during the exchange process.
Site 2
A series of on-site acute toxicity tests using D. magna
revealed that the final undiluted effluent at Site 2
was consistently toxic to D. magna.
An investigation was initiated, using D. magna as
the test organism, to determine if the specific toxic
agents could be isolated. ESC initially attempted to
determine if metals could be responsible for the
toxicity by adding a chelator (1 mg/L sodium NTA),
which would bind with the metals (does not bind the
hexavalent chromium) and prevent their uptake by
the test species. The addition of NTA, however, had
no effect in reducing effluent toxicity. Sodium
thiosulfate (1.0 mg/L) and sodium sulfite (4.2 mg/L)
were added to the wastewater to neutralize any
chlorine and biocide which may have been present.
These compounds also failed to reduce effluent
toxicity.
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D. magma toxicity tests, ICP, TOG and hexavalent
chromium analyses were also conducted at various
locations along the wastewater drainage system in
an attempt to determine if a source of toxic agent
could be identified. Although no correlation was
found between toxicity and the TOG and ICP results,
a correlation was found between hexavalent
chromium levels and toxicity. The results illustrated
that the most upstream sample (sampling point A)
had the lowest concentration of hexavalent
chromium (29 ppb) and exhibited the least acute
toxicity to D. magna (48 ECso = 80 percent effluent).
On the other hand, samples collected at sampling
point B and other locations along the wastestream
exhibited increases in both effluent toxicity and
hexavalent chromium levels. Final untreated
effluent (containing 241 ppb of hexavalent
chromium) produced 100 percent mortality within 48
hours.
Once this relationship was observed, the ESC team
fractioned the wastewater by passing 200 ml
subsamples of the effluent through granular
activated carbon, cation and anion exchange resins.
They then evaluated the wastewater for acute
toxicity to D. magna. The team also monitored the
hexavalent chromium concentrations prior to and
after each treatment to establish a correlation
between toxicity and hexavalent chromium. The
results of these studies indicated that there was a
direct correlation between hexavalent chromium and
toxicity to D. magna.
Treatment of the wastewater with anion exchange
resin and activated carbon, resulted in no mortality
to D. magna. The concentrations of hexavalent
chromium in these treatments were 10 ppb (anion
resins) and 20 ppb (activated carbon resin), which are
below or near the lowest reported acute level for
Daphnia. The cation resin failed to lower the
concentration of hexavalent chromium (210 ppb).
This treatment provides further evidence that
hexavalent chromium was likely responsible for
wastewater toxicity.
To confirm whether the acute toxicity originally
observed in the final effluent at Site No. 2 was due to
hexavalent chromium, ESC plotted and analyzed
dose-response curves for effluent and hexavalent
chromium (synthetic effluent) toxicity tests. The 48
hour ECso f°r hexavalent chromium concentrations
in the effluent (35 ppb) was compared to the 48 hour
ECso (41 ppb) for the hexavalent chromium in the
synthetic effluent. The similarities between these
two concentrations supported the hypothesis that
hexavalent chromium was likely responsible for the
observed toxicity. Further confirmation of chromium
as the toxic component was supported by the fact that
when the plant stopped using hexavalent chromium,
the wastewater became nontoxic.
Site 3
To determine if salinity could be responsible for Site
No. 3 effluent's toxicity ESC conducted a comparative
acute toxicity study by subjecting fathead minnows
to the final effluent (from the plant discharge) and a
synthetic effluent (a solution of sodium chloride,
calcium chloride and well water). The concentrations
of Na, Ca and chloride were similar to those
occurring in the natural effluent (Na = 1020 mg/L,
Ca = 3000 mg/L, Cl = 7310 mg/L). The results of this
comparative study indicated that salinity could be
responsible for the toxicity of the effluent since
essentially identical 96 hr LCso values were observed
for the natural effluent (LCso = 79 percent) and
synthetic effluent (LCso = 70 percent).
ESC then conducted fractionation tests on effluent
samples to verify the causative agents by passing
effluent over four separate resins (granular activated
carbon, cation exchange resin, anion exchange resin
and cation followed by anion exchange resin). D.
magna acute toxicity tests conducted before and after
resin treatment indicated that neither the activated
carbon, nor cation/anion exchange resins could
eliminate effluent toxicity. No correlation existed
between toxicity and TOG. However, a correlation did
exist between toxicity and calcium and/or chloride
ion concentrations since the concentrations of
calcium and chloride in the final effluent, activated
carbon, and anion exchange resin treatments were
well above the acute toxicity concentrations for D.
magna.
The fact that calcium was one of the toxic components
in the effluent was further verified by a comparison
of the calcium concentration in the effluent and
corresponding dose response curve to reported effect
levels (Rodgers, et al. 1987) for calcium in fathead
minnows (96 hr LC$Q values = 2766 mg/L). Based on
the test data, the 96 hour LCso for the natural
effluent was 79 percent. The calcium concentration in
the 100 percent effluent was 3000 mg/L with a
predicted nominal calcium content in the 79 percent
effluent of 2400 mg/L indicating a correlation
between calcium concentration and toxicity.
Additional synthetic and natural effluent toxicity
tests were conducted to verify calcium and chloride
ions as the toxic components. Approximately one-half
of these tests showed a strong correlation between the
synthetic and final effluents. The fact that no
correlation was observed between some of the tests
indicated that another factor(s) may at times be
responsible for the toxicity of the effluent.
ESC confirmed that calcium and chloride ions were
the sources of toxicity to D. magna in the effluent by
preparing a synthetic effluent which contained (only)
calcium, sodium and chloride ions and compared the
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dose response curves of the tests with dose response
curves using the final effluent which contained the
same concentrations of calcium, chloride and sodium
ions. A distinct relationship was observed in these
test results and this in effect established and
confirmed that calcium and chloride ions were
principally responsible for the effluent toxicity.
Toxicity Reduction Approaches
Sitel
The final effluent from Site 1 was evaluated for acute
toxicity to D. magna after passing the effluent
through granular activated carbon, cation and anion
resin, combination treatment and the zeolite
treatment. The absence of mortality in the treated
final effluent showed that the concentration of
ammonia was reduced to below the acute toxicity
threshold.
Problems Encountered
Sitel
The hypothesis that an unknown toxic component
was coming off the cation exchange resin was
confirmed when a 300 mg/L NH4C1 stock solution in
well water was passed through the cation column.
Toxicity persisted after treatment even though
ammonia levels had been reduced to < 1 mg/L, which
was well below 32 mg/L (48 hr ECso). No toxicity was
observed when well water alone was passed through
the resin.
ESC was unable to reduce ammonia below effect
levels in the wastewater using air stripping methods.
The use of zeolite resins was the only effective means
for removing ammonia.
Site 2
The toxicity of the original effluent to D. magna was
eliminated through treatment of the effluent with
activated carbon and anion exchange resin. These
techniques in effect reduced the concentration of
hexavalent chromium which was responsible for the
effluent toxicity. ESC also examined other treatment
methods such as cation exchange resin. However,
this technique failed to reduce toxicity.
Site 3
The TIE study indicated that a combination of anion
and cation exchange resins eliminated toxicity in the
final effluent.
Follow-Up and Confirmation
Site 2
ESC reevaluated the effluent for acute toxicity after
the management at Site 2 permanently eliminated
the use of hexavalent chromium. On doing so, the
toxicity of the final effluent was then monitored and
found to be nontoxic to D. magna. The results
demonstrated a useful modification in the water
treatment practices at Site 2.
References
Doi, J. and P.R. Grothe. "Use of Fractionation/
Chemical Analysis Schemes for Plant Effluent
Toxicity Evaluations." Aquatic Toxicology and
Hazard Assessment; Eleventh Symposium,
American Society for Testing and Materials,
Philadelphia (1987).
Rodgers, J.H.,et al. "Toxicity of Calcium to Bioassay
Species." Submitted for publication to Bulletin of
Environmental Contamination and Toxicology
(1987).
Walsh, G.E. and R.L. Garnas. "Determination of
Bioavailability of Chemical Fractions of Liquid
Wastes Using Freshwater and Saltwater Algae
and Crustaceans." Environmental Science
Technology, 17:180-182 (1983).
fr U.S. GOVERNMENT PRINTING OFFICE. 1989- 648-163' 00310
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