<>EPA
United States
Environmental Protection
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C. 20460
OFFICE OF
WATER
MEMORANDUM
SUBJECT: Pretreatment Program Guidance
FROM: James/KT 'eider , Director
Off-ice of Water Enforcement
"and Permits (EN-335)
TO: Users of the Guidance Manual for
Preventing Interference at POTWs
This guidance manual was developed by EPA to aid publicly
owned treatment works (POTWs) in identifying, tracking, and
mitigating interference episodes caused by discharges of
nondomestic wastes. Interference is defined in the General
Pretreatment Regulations (40 CFR Part 403) in terms of a
discharge which, alone or in combination with other discharges,
inhibits or disrupts the POTW and causes it to violate its
NPDES permit or applicable sludge use or disposal regulations.
The legal responsibilities of POTWs and their industrial
users for avoiding interference are specified in the General
Pretreatment Regulations. The basic regulatory requirements
are explained in this manual and technical guidance is provided
to help POTW operators detect and determine the sources of
interference.
This document will be useful to all POTWs that may
experience interference problems, not just those that, have
been required to establish federally-approved pretreatment
programs. Therefore, EPA is distributing it widely. Additional
copies of this guidance manual or further information about
the national pretreatment program can be obtained by writing to
the Permits Division, (EN-336), US EPA, 401 M St., S.W.,
Washington, D.C. 20460.
EPA is preparing another guidance document thac deals
specifically with the development of local limits to prevent
interference and pass through. It was distributed in draft
form for comment to States and EPA Regions in May 1987 and
will be mailed to all POTWs with federally-approved pretreatment
programs when final. Additional information about the local
limits guidance document can also be obtained from the Permits
Division.
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GUIDANCE MANUAL
FOR
PREVENTING INTERFERENCE AT POTWs
September, 1987
U.S. Environmental Protection Agency
Office of Water
Office of Water Enforcement and Permits
401 M Street, S.W.
Washington, D.C. 20460
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ACKNOWLEDGEMENTS
This document was prepared by James M. Montgomery, Consulting Engineers,
Inc. under EPA Contract No. 68-03-1821. Mr. John Grantham was the Project
Manager, with Dr. Edward Wetzel and Mr. Scott Murphy acting as Project
Engineer and Assistant Project Engineer, respectively. Messrs. Wetzel and
Murphy are the principal authors of this manual. Treatment plant site visits
conducted as part of the case study effort were made by Messrs. David Harrison,
Paul Skager and Roger Stephenson and Ms. Sheila McShane, in addition to the
authors. The contributions of a number of other members of the Pasadena office
support staff to the production of this manual are gratefully acknowledged.
This manual was prepared under the technical direction of Ms. LeAnne Hammer
and Mr. Gregory McBrien of the Permits Division, Office of Water Enforcement
and Permits, and Dr. Sidney Hannah of the Water Engineering Research
Laboratory (WERLl. Additional guidance and assistance were provided by the
other members of the Pretreatment Support Group of WERL, consisting of
Messrs. James Kreissl, Dolloff Bishop, Richard Dobbs, Kenneth Dostal and Henry
Tabak. Peer review and comments were also provided by Science Applications
International Corporation (SAIC) under EPA Contract No. 68-01-7043. Special
thanks are also offered to Mr. Guy Aydlett of the Hampton Roads Sanitation
District and to Mr. Paul (Kip) Keenan of the City of Baltimore Pollution Control
Section.
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TABLE OF CONTENTS
Page
Acknowledgements i
Table of Contents ii
List of Tables iv
List of Figures v
1. Introduction 1
1.1 Background 1
l.Z Definition of Interference 2
1.3 Guidance Manual Objectives 4
2. Detecting Interference 6
2.1 Types of Interference 6
2.1.1 Chronic Inhibition 8
2.1.2 Upset Conditions 8
2.2 Interference - Causing Substances 9
2.2.1 Conventional Pollutants 11
2.2.2 Metals and Other Inorganics 11
2.2.3 Organic Compounds 12
2.3 Sewer Collection System 12
2.4 Plant Operations 14
2.4.1 Observation 14
2.4.2 Instrumentation 15
2.4.3 Analytical Results 15
2.5 Waste water Monitoring 16
2.5.1 POTW Influent 16
2.5.2 Other POTW Locations 17
2.5.3 Inhibitory Effects Testing 18
3. Source Identification 29
3.1 Chronic Discharges 30
3.1.1 Routine Monitoring 31
3.1.2 Tracking Program 32
3.2 Isolated Spills and Unauthorized Discharges 33
3.2.1 Hauled Wastes 35
3.3 Rapid Screening Techniques 36
3.4 Summarv 37
11
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Page
4. Mitigation 43
4.1 Treatment Plant Control 43
4.1.1 Biological Process Control 43
4.1.2 Biological Augmentation 45
4.1.3 Chemical Addition 45
4.1.4 Operations Modification 46
4.1.5 Physical Modification 47
4.1.6 Summary 48
4.Z Pretreatment and Source Control 49
4.2.1 Local Limits 49
4.2.2 Accidental Spill Prevention 49
4.2.3 Pretreatment Facilities 50
4.2.4 Regulation of Waste Haulers 50
4.2.5 Planning for Future Sources 51
4.3 Legal and .Enforcement Remedies 52
4.3.1 Penalties 53
4.3.2 Orders and Compliance Schedules 54
4.3.3 Litigation 54
4.3.4 Sewer Disconnection or Permit Revocation 54
References 61
Appendix A - Case Studies
Back River (Baltimore, MD) A-3
Patapsco (Baltimore, MD) A-6
Bayshore Regional (Union Beach, NJ) A-9
East Side Plant (Oswego, NY) A-12
Hamilton Township (Trenton, NJ) A-15
Horse Creek (North Augusta, SC) A-18
Maiden Creek (Blandon, PA) A-21
Metro-West Point (Seattle, WA) A-24
Neuse River Plant (Raleigh, NC) A-27
Newark, OH A-30
North Shore (Gurnee, IL) A-33
Passaic Valley (Newark, NJ) A-36
Sioux City, IA A-39
Tolleson, AZ A-42
Appendix B - Interfering Substances B-l
111
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LIST OF TABLES
No. Title Page
2-1 Metal, Cyanide and Inorganic Compound 20
Concentrations Inhibiting Biological
Processes
2-2 Organic Compound Concentrations Inhibiting 21
Biological Processes
2-3 Waste Characteristics Pertaining to Hazards 22
in Collection Systems
2-4 Interference Identification Through 23
Plant Observation
2-5 Instrumentation of Plant Processes and 26
Wastestreams
2-6 Analytical Monitoring of Plant Processes 27
2-7 Methods for Evaluating Inhibitory Effects 28
of Industrial Wastewaters
3-1 Industrial Spills of Hazardous Materials: 38
Impact on Sewer Collection System
3-2 Industrial Spills of Hazardous Materials: 39
Impact on Treatment Plant
3-3 Impacts of Waste Hauler Discharges on POTWs 40
4-1 Biological Process Control Steps 56
4-2 Chemical Additions 57
4-3 Treatment Plant Control Measures 58
A-l Case Study Summary Table A-l, 2
A-2 Average Metal Content of Back River Sludge A-4
IV
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LIST OF FIGURES
No. Title Page
3-1 Treatment Plant Upset Identification Procedures 41
3-2 HRSD Source Tracking Procedure 42
4-1 Fundamental Procedures for POTW ASPP Development 59
4-2 Procedures of a Waste Hauler Permit Program 60
A-l Monthly Acute Toxicity (Patapsco/Baltimore, MD) A-7
A-2 Impact of Industrial Waste Discharge on POTW A-10
Loadings (Bayshore/Union Beach, NJ)
A-3 Horse Creek Pollution Control Facility A-19
Influent pH
A-4 Wastewater Discharge at Influent Metering A-21
Station (Maiden Creek/Blandon, PA)
A-5 West Point Chromium Concentrations (Seattle, WA) A-25
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NOTE TO USERS OF THE GUIDANCE MANUAL
The case studies contained in Appendix A, and referred to throughout the text
were conducted over a period from December, 1985 to March, 1986. The
information contained in each discussion was current at that time, but since then
the status of some of the activities at the case study sites is likely to have
changed.
VI
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1. INTRODUCTION
i.I BACKGROUND
Sections 307(b)(l) and (c) of the Clean Water Act (CWA) direct the U.S.
Environmental Protection Agency (EPA) to establish pretreatment standards "to
prevent the discharge of any pollutant through treatment works... which are
publicly owned, which pollutant interferes with, passes through, or is otherwise
incompatible with such works." These sections address the problems created by
discharges of pollutants from nondomestic sources to municipal sewage
treatment works. Specifically addressed are discharges of pollutants which
either interfere with the operation or performance of the works or pass through
the works to navigable waters untreated or inadequately treated. Pretreatment
standards are intended to prevent these problems from occurring by requiring
nondomestic users of publicly owned treatment works (POTWs) to pretreat their
wastes before discharging them to the POTW. In 1977, Congress amended
Section 40Z(b)(8) of the CWA to require POTWs to help regulate their industrial
users (IDs) by establishing local programs to ensure that industrial users comply
with pretreatment standards.
In establishing the national pretreatment program to achieve these goals, the
EPA adopted a broad-based regulatory approach that implements the statutory
prohibitions against pass-through and interference at two basic levels. The first
is through the promulgation of national categorical standards which apply to
certain industrial users within selected categories of industries that commonly
discharge toxic pollutants. Categorical standards establish numerical,
technology-based discharge limits derived primarily to control the discharge of
toxic pollutants which could interfere with or pass through POTWs. The EPA has
promulgated categorical standards for many major and minor industry categories
(See 40 CFR Parts 400-469). The EPA will be evaluating these industries and
other industries for the control of additional toxic pollutants.
Implementation of the categorical standards will not remedy all the interference
and pass-through problems that may arise at a POTW. The potential for many
pass-through or interference problems depends not only on the nature of the
discharge but also on local conditions (e.g., the type of treatment process used
by the POTW, local water quality, the POTW's chosen method for handling
sludge), and thus needs to be addressed on a case-by-case basis. Such problems
can result from discharges by categorical industries of pollutants not covered by
a categorical standard or from nondomestic sources not regulated by the
categorical standards. In addition, since categorical standards are established
indu3try-wide, they cannot consider site-specific conditions, and therefore, may
not be adequate to prevent all pass-through and interference even for the
regulated pollutants. The second level of EPA's regulatory approach, contained
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in the General Pretreatment Regulations (40 CFR Part 403), addresses these
areas of concern. First, Section 403.5(b) establishes specific prohibitions which
apply to all nondomestic users and are designed to guard against common types
of pollutant discharges that may result in interference and pass-through (e.g., no
discharge of flammable, explosive, or corrosive pollutants). Second,
Section 403.5(a) establishes a general prohibition against pass-through and
interference which serves as a back-up standard to address localized problems
that occur. In addition, POTWs with total design flow greater than 5 mgd and
which receive pollutants which pass through or interfere with POTW operation or
are otherwise subject to pretreatment standards must establish formal
pretreatment programs which must be approved by the EPA or a designated
State agency. POTWs with design flow less than 5 mgd may also be required to
develop pretreatraent programs if circumstances warrant in order to prevent
pass-through or interference. As part of their programs, POTWs must develop
and enforce specific local limits to prevent pass-through and interference.
POTWs not required to develop pretreatment programs may still be required to
develop local limits if they experience pass-through or interference that is likely
to recur (Section 403.5(c)).
The need for guidance on preventing interference was identified by the
Pretreatment Implementation Review Task Force (PIRT). PIRT was established
on February 3, 1984 by the EPA Administrator. The task force was composed of
17 representatives from POTWs, States, industry, environmental groups and EPA
Regions. The charge given to PIRT was to make recommendations to EPA
concerning the problems faced by POTWs, States, and industry in implementing
the national pretreatment program. In its Final Report to the Administrator
(U.S. EPA, 1985b), one of the specific problems identified by PIRT was the
difficulty experienced by POTWs in the recognition, tracking, and mitigation of
interferences caused by industrial discharges. PIRT's recommendation was for
EPA to provide guidance to municipalities regarding such interference problems.
This report is EPA's response to that recommendation.
1.2 DEFTNITION OF INTERFERENCE
The U.S. EPA recently promulgated revised definitions for the terms "pass
through" and "interference" (52 Federal Register 1586, January 14, 1987). As
defined in 40 CFR, Part 403.3(i):
(i) The term ''Interference" means a discharge which, alone or in
conjunction with a discharge or discharges from other sources, both:
(1) Inhibits or disrupts the POTW, its treatment processes or
operations, or its sludge processes, use or disposal; and
(2) Therefore is a cause of a violation of any requirement of the
POTW's NPDES permit (including an increase in the magnitude
or duration of a violation) or of the prevention of sewage sludge
use or disposal in compliance with the following statutory
provisions and regulations or permits issued thereunder (or more
stringent State or local regulations): Section 405 of the Clean
Water Act, the Solid Waste Disposal Act (SWDA) (including
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Title n, more commonly referred to as the Resource Conserva-
tion and Recovery Act (RCRA), and including State regulations
contained in any state sludge management plan prepared
pursuant to Subtitle D of the SWDA), the Clean Air Act, the
Toxic Substances Control Act, and the Marine Protection,
Research and Sanctuaries Act.
In the same rulemaking that established the new definitions (52 Federal Register
1586, January 14, 1987), EPA amended the General Pretreatment Regulations to
establish affirmative defenses to liability on the part of an industrial user for
violating the general prohibitions or certain of the specific prohibitions. These
defenses address situations where an industrial user did not know or have reason
to know that its discharge would cause interference. The reader is referred to
the Federal Register citation above for additional information and perspective,
as provided in the preamble to the regulation.
The interference prohibition addresses situations where an industrial user's
discharge, either alone or in conjunction with other discharges, disrupts the
POTW or its sludge practices, and the disruption is a cause of a permit violation
or prevents the POTW from lawfully using its chosen sludge use or disposal
method. In contrast, the pass-through prohibition addresses situations where an
IU's discharge exits the POTW to waters of the United States in quantities or
concentrations which, alone or in conjunction with other discharges, cause a
permit violation. Pass-through is not necessarily related to an inhibition or
disruption of the POTW processes, but instead is related to a pollutant discharge
which is not susceptible to adequate treatment by the POTW.
An industrial user whose discharge is found to cause pass-through or interference
is legally liable for violating the general prohibitions, and may be subject to
enforcement action. However, as discussed in the Federal Register preamble to
the new definitions of pass-through and interference, an industrial user's
discharge is considered to be interference or pass-through only if the discharge
is a cause of the POTW's noncompliance. If a malfunction or improper operation
by the POTW, rather than an industrial user's discharge, causes the POTW's
noncompliance with its NPDES permit or sludge requirements, interference
and/or pass-through are not occurring. The EPA intends the definitions to be
interpreted and implemented in a manner consistent with the Congressional
intent that pretreatment technology not be required as a substitute for adequate
operation and maintenance of the POTW. Thus, if the POTW's improper
operation alone prevents it from meeting the effluent limitation in its NPDES
permit, the POTW must correct its operational problem.
The interference definition does not directly address situations in which a
discharge causes problems other than NPDES permit violations or impairment of
sludge use or disposal. For example, POTW worker health and safety problems or
unacceptable air emissions could result from IU discharges. The EPA is
currently considering whether and how to address these problems more
specifically through guidance and future regulations, if appropriate, and by
encouraging POTWs to address these concerns in their local ordinances. This
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manual addresses such concerns to only a limited degree, focusing mainly on
interference as defined in the above-mentioned regulation.
1.3 GUIDANCE MANUAL OBJECTIVES
The purpose of this manual is to provide POTW operators with guidance on
dealing with interferences caused by pollutants from nondoznestic sources. In
addition, some guidance is provided on distinquishing interferences caused by
nondomestic discharges from problems resulting from poor operation and main-
tenance of the POTW. This manual is divided into three major sections, which
correspond to the order in which a POTW should address interference. These
sections are:
• Detecting Interference
• Source Identification
• Mitigation
The section on detecting interference is intended to help identify the types of
interferences and substances which are known to cause problems. The way in
which interference occurs in both the sewer collection system and the treatment
plant is also discussed, along with analytical tests and monitoring that can be
conducted by POTW operators.
The second major section deals with the identification of the industrial sources
of the interference-causing substances. Sources can be separated into chronic
dischargers of industrial pollutants, isolated spill events, and hauled wastes.
Identification techniques range from simple sensory observations to the use of
sophisticated monitoring equipment for tracing problems at the POTW back to a
source.
The final section on mitigation discusses ways in which municipalities can cope
with interference problems. In-plant control, source control and legal and
enforcement remedies are addressed in the section. Operators should be
cautioned that there are few straightforward solutions to these problems, and
that often a combination of techniques will need to be employed to properly
mitigate an interference. The section concludes with a discussion on planning, so
that future industrial discharges will not interfere with successful POTW
operations.
There are two appendices included in the back of this manual. Appendix A
contains case studies of 14 POTWs, visited as part of this project, that have
previously experienced interferences but have mitigated the problems over the
past few years. These cases are referred to throughout the manual wherever a
certain case study illustrates a particular problem or solution that is discussed.
While the case studies represent some of the iypes of interference problems
experienced by POTWs, they should not necessarily be viewed as examples of
pretreatment programs which are ideally implemented or fully endorsed by the
EPA. It is hoped that the case studies will be useful to people who are
experiencing problems similar to those described. A summary of the case studies
including the names and phone numbers of individuals who can be contacted for
further information is provided on Table A-l. Appendix B is a list compiled from
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the published literature and actual treatment plant studies that includes many of
the inorganic and organic substances now recognized as having the potential to
cause interference.
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2. DETECTING INTERFERENCE
2.1 TYPES OF INTERFERENCE
Interference can be broken down into two basic types: (1) interference with the
POTW's ability to meet its NPDES permit; and (2) interference with its ability to
utilize its chosen sludge disposal method. With either type, several sources may
contribute to the interference. For example, contamination of sludge with
unacceptable levels of metals may be due to the cumulative contributions from
several industries. Domestic sewage background concentrations can also be a
significant source of some metals. Unless the interference is caused solely by
domestic sources or inadequate operation and maintenance of the POTW, each
nondomestic source of the interfering pollutant should be identified and its role
in causing the interference assessed. The individual sources must then be
controlled as necessary to allow the POTW to meet its NPDES permit and utilize
its chosen sludge disposal method.
Industrial users discharges can cause the first type of interference, involving a
permit violation, by several means. These include, but are not limited to:
9 physically disrupting the flow of wastewater through the POTW's
system
• chemically, physically, or thermally inhibiting the treatment
processes
• hydraulic ally overloading the plant so that proper settlement does not
occur or wastes are retained for too short a time to receive adequate
treatment before discharge.
The pollutants discharged by the industrial user that cause the POTW to violate
its permit may be the same as, or different from, the pollutants discharged in
violation of the permit. For example, an industrial user discharging excessive
BOD that causes a disruption of the biological treatment process and results in
the POTW exceeding its BOD discharge permit limit may be causing an
interference. Likewise, the same industrial user discharging a toxic pollutant
that inhibits the POTW's performance and results in effluent BOD permit
violations is also causing an interference. It should be noted that in the example
of an excessive BOD discharge causing a BOD permit violation, the problem
could be pass-through rather than interference. For example, a heavy discharge
of relatively non-degradable organic matter might pass through the plant without
causing an upset. The distinction between pass-through and interference must be
made depending of the individual circumstances of such cases.
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The second type of interference, impairment of sludge use or disposal, results
when the POTW's sludge no longer meets applicable requirements for its chosen
use or disposal alternative. Thus, if the POTW has elected to apply the sludge to
land but industrial discharges prevent the lawful implementation of this method,
interference occurs. Detection of this type of interference is generally
performed by sludge monitoring coupled with monitoring of industrial users.
As mentioned in Chapter 1, any type of interference is a violation of the general
prohibition (40 CFR Part 403.5(a)). Some interferences are also violations of the
specific prohibitions (40 CFR Part 403.5(b)). The specific prohibitions bar
discharges which:
1. create a fire or explosion hazard;
2. are corrosive to POTW structures;
3. obstruct wastewater flow resulting in interference;
4. release pollutants (including BOD) at rates or concentrations which
will cause interference; or
5. increase the influent wastewater temperature above 40°C, or inhibit
biological activity due to heat, resulting in interference.
The problems referred to by the specific prohibitions do not always result in
interference (ie., permit violations), yet they are detrimental to POTW
operations. In fact, many local sewer use ordinances contain additional or more
stringent local prohibitions, such as a prohibition against discharges which
release toxic vapors endangering POTW worker health and safety. The EPA
strongly supports and encourages such local prohibitions.
Another way of looking at types of interference is to classify them by the
location of impact: either the collection system or the treatment plant.
Collection system problems (corrosion of sewer mains, explosions in sewers, etc.)
are generally easier to relate to industrial or commercial discharges, while
interference at the treatment plant requires detailed analysis to ensure that it is
not the result of poor operation and maintenance practices or from domestic
sources. Since it is often the most difficult to detect and trace to industrial
sources, this chapter emphasizes treatment process interference. The chapter
looks at both chronic inhibition and upset conditions. The ability of a particular
waste discharge to cause inhibition or upset is considered in terms of three
factors:
• industrial discharge practices
• acclimation of POTW treatment processes to the specific
pollutants
• impacts on the POTW
The next two subsections will discuss chronic inhibition and upset conditions in
more detail. Collection system problems are discussed in Section 2.3.
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2.1.1 Chronic Inhibition
Chronic inhibition refers to a more or less consistent pattern of impairment of
the functioning of the biotnass in a biological treatment process caused by
influent pollutant concentrations that are above tolerable levels. Inhibition is
usually defined by a decrease in oxygen uptake rate or a decrease in COD/BOD
removal. If the inhibition leads to a permit violation, it then is classified as
interference. This type of interference results from either a continuous or
semi-continuous discharge of an industrial pollutant to the POTW. Chronic
inhibition may also result from the total effect of several industries discharging
a variety of inhibitory pollutants. Industrial sources of chronic problems tend to
be by-products of production activities such as chemical derivatives, rinse
waters and contact cooling water.
The effects of an inhibitory pollutant on plant biomass vary depending on how
frequently and at what level the pollutant is discharged. The more consistently a
pollutant is fed to the biological treatment process, the more chance the biomass
has to develop a "resistance" to the pollutant. If a pollutant is fed at a fairly
even rate and concentration, the biomass will generally eventually become
accustomed to or "acclimate" to the polluant, and BOD removal efficiency will
no longer suffer. For this reason, a plant may experience operational problems
unless there has been sufficient time for the biomass to become acclimated. In
addition, discharges of toxics at high enough concentrations can cause inhibition
even in acclimated systems.
Although it does not always result in a POTW violating its NPDES permit limits,
chronic inhibition can increase the overall expense and difficulty of operating a
treatment plant in compliance with NPDES permit limits. For example, a plant
may have to be operated at an increased MCRT or require additional aeration
capacity to counteract the negative effects of inhibition. Depending on the
circumstances, this may involve significantly increased operating costs for
recirculating sludge at a higher rate or providing more aeration. It may also
take away any reserve capacity that the plant might otherwise have had for
future growth. Therefore, POTW's experiencing chronic inhibition should take
steps to mitigate it even when there is no immediate threat of an NPDES permit
violation.
2.1.2 Upset Conditions
The results of 29 case studies performed in conjunction with the development of
this manual showed that most interference problems are caused by intermittent
discharges of high-strength conventional wastes which overload a POTW's
organic capacity, causing plant upset. The term "upset" is used in this manual to
refer to an exceptional incident which creates a temporary non-compliance with
permit limits due to the impacts of the incoming waste characteristics on the
treatment processes. Discharges causing upset commonly come from food
processors such as bakeries, dairies, breweries, canneries, poultry farms and
meat packaging plants. Examples of interferences due to high-strength
conventional wastes are provided by the Bayshore Regional Sewerage
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Authority (New Jersey), and Hamilton Township (New Jersey) case studies in
Appendix A. In some cases, upsets have occurred even when the total industrial
contribution was significantly less than 5 percent of the total plant flow. It is
frequently the intermittent discharge of concentrated wastes which leads to the
upset.
Similarly, in cases of plant upsets due to the discharge of toxic pollutants, it is
usually the intermittent discharges of toxics which produce the most drastic
effects. These types of discharges may result from:
process tank contents disposal
cleanup operations
industrial spills
waste hauler discharges
midnight dumping (illegal waste hauling)
Biological populations are typically not acclimated to either the specific
compounds or concentration levels observed in such discharges. The impacts on
biological processes can therefore be severe and rapid, often requiring long
recovery periods. Such interferences commonly affect the effluent quality
rather than the stabilized and dewatered sludge characteristics, although the loss
of an anaerobic digester due to slug loads of heavy metals is not unusual. A slug
load is defined as any pollutant in a discharge at a flow rate and/or pollutant
concentration which will cause interference at the POTW.
It is important that POTWs monitor the occurrence of upset conditions caused by
industrial waste discharges. In some cases, the problems may recur in a cyclical
pattern, such as once-per-week or once-per-month. Recognition of the pattern
coupled with contaminant identification will go a long way toward discovering
the source of the problem. Intermittent discharges of this type tend to produce
similar impacts on the POTW from incident to incident. Changes in'dissolved
oxygen (DO) levels, mixed liquor suspended solids (MLSS), sludge volume index
(SVI), reactor temperature, etc. are all indications of process changes potentially
resulting from industrial wastes.
The impacts of interference-causing substances are not restricted to biological
systems within a treatment facility. Interference problems can also surface in
physical treatment systems (clarifiers, thickeners, filters, etc.) or in the sewer
collection system. Municipalities should make every effort to mitigate
discharges that threaten any treatment process as well as the integrity of the
collection system, not only to avoid interference, but for the protection of
worker health and safety as well.
2.2 INTERFERENCE-CAUSING SUBSTANCES
POTW interference can be caused by a wide variety of chemical, biological and
physical factors. Chemical factors such as the types and concentrations of
industrial wastevrater constituents which cause interference are highly variable.
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The studies reported in the literature discussing chemical interference/inhibition
range from research done in the laboratory to studies of actual treatment plant
operations. There has been a substantial body of work published and many
researchers have devoted a great deal of effort to these types of studies.
Previous reviews (U.S. EPA, 1979; Geating, 1981; U.S. EPA, 1981a; Russell, et
al., 1983; U.S. EPA, 1986a) have presented ranges of concentrations for a variety
of pollutants which inhibit biological processes. The reader should refer to these
documents for a more thorough presentation of pollutant treatability and process
inhibition. As an aid to POTW operators, this manual compiles available
information on the types and concentrations of pollutants and compounds which
inhibit some biological treatment systems.
There are various ways of measuring inhibition and the fact that different
researchers use different methods results in a range of published "inhibiting
concentrations", even for nearly identical study conditions. The two most
typical methods of determining activated sludge inhibition are by measuring
1) decreases in COD or BOD removal or Z) decreases in oxygen utilization rates.
Threshold inhibition levels as measured by these two methods are usually defined
differently by individual researchers, but are most typically set at the
10-50 percent range. Anaerobic trpatm^nt inhibition, is typically defined as
increased volatile acid levels or decreased methane generation, but once again
the threshold levels are variously defined. Nitrification inhibition is specified as
a decrease in the degree of ammonia conversion.
The most important conditions that affect biological inhibition are:
the nature and strength of the inhibiting agent
biomass characteristics
pH
temperature
synergism
antagonism
acclimation
For most studies, biomass characteristics are not described in the literature,
except as related to whether or not the biomass was acclimated. The diverse
biomass population is likely to be very different from one reported study to the
next. Characteristics such as sludge age or food to microorganism (F/M) ratio
will have a significant impact on the inhibitory concentration levels of pollu-
tants. Actual test conditions, including temperature and pH, vary dramatically
from study to study, with the result being that inconsistent values are reported.
Waste-water pH plays a particularly vnportant role in metal-caused inhibition.
The pH affects the solubility of metal ions, and it is primarily the soluble metal
that is toxic to microorganisms. Synergism, or the increase in the inhibitory
effect of one substance by the presence of another, is most important when
considering combinations of metals. Toxic organics do not exhibit this effect as
often as metals. On the other hand, some compounds are antagonistic towards
each other, decreasing the inhibitory effect of either compound alone. Examples
are chelating agents, such as EDTA, which are antagonistic toward metal ions
and reduce their toxic effects.
10
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Substances which cause interference/inhibition problems can be divided into
three groups:
• conventional pollutants
• rnetals and other inorganics
• organic compounds
Each of these categories is considered separately in the subsections to follow.
2.Z.I Conventional Pollutants
The terra "conventional pollutants" as used in this manual includes BOD,
suspended solids, pH, and oil and grease. Since BOD and suspended solids (SS)
form the usual basis of secondary treatment plant design, interference/inhibition
problems result from exceeding the peak mass loadings specified by the design.
Such "shock loadings" (slug loadings) of conventional pollutants are a common
cause of permit violations resulting from oxygen transfer limitations,
insufficient biodegradation and solids carryover. Oil and grease are normal
constituents of domestic wastewater that if present in elevated concentrations
nan interfere with normal waste treatment by preventing bacteriological floe
from properly settling and disrupt mechanical equipment operation. The pH of a
wastewater can also cause interference if it is too high or too low, or is widely
fluctuating.
2.Z.Z Metals and Other Inorganics
More research efforts have been directed toward the impacts of heavy metals on
biological treatment than any other classification of contaminant found in
wastewater. A large percentage of the insoluble metals and metal salts that
enter a POTW settle out during primary clarification. Consequently, a signifi-
cant impact of metals is in rendering sludges unacceptable for a variety of
disposal options, notably landspreading for agricultural purposes.
The soluble fractions of the metals can upset the secondary treatment processes.
Table 2-1 presents ranges of metal and other inorganic pollutant concentrations
inhibiting biological processes. Important factors affecting these ranges of
values are pH, solubility, and the definition of inhibition used by the researchers
reporting the results. The wide range of concentrations presented results from
apparently contradictory data published in the literature. The values presented
in Table 2-1 represent the range of reported threshold inhibition concentrations.
Acclimation is an important issue, which in many studies was either not reported
or was not known. However, it would be reasonable to expect the lower end of a
range to correspond to threshold levels inhibiting an unacclimated system while
the upper end of the range would correspond to threshold levels inhibiting an
acclimated system. The primary references, for this table are U.S. EPA (1981a),
Russell, et al., (1983) and Geating (1981). U.S. EPA (1986a) provides a more
complete reference list.
The inhibition levels presented in Table 2-1 are for the dissolved metal unless
otherwise indicated. The dissolved form is the most toxic. However, POTWs
11
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should control the total metal entering the plant because participate metal or
metal compounds may exert some toxicity or may later be resolubilized. The
dissolved metals present in the secondary treatment process are derived both
from dissolved metals in the plant influent and from desorption of metals from
sludges that are recycled to secondary treatment, A large percentage of the
toxic metals present in the aeration basins at some treatment plants has been
found to be contributed by recycled solids handling sidestreams. Such
contributions can cause a continued toxic effect long after the source has been
controlled.
Z.Z.3 Organic Compounds
Considerable interest exists among the EPA and public health officials
concerning the fate and effects of toxic organic compounds in POTWs. Organic
substances which enter municipal facilities are either removed in the biological
treatment processes, inhibit biological degradation, or pass through the plant.
The principal removal mechanisms are:
• volatilization
• biodegradation
• adsorption to biological fiocs and settling
The amount of information available on the impacts of organic contaminants is
small compared with the metals, due in large part to the number of compounds
of interest and also to the sophisticated analytical equipment required to
measure these organics. Table 2-2 presents ranges of concentrations for toxic
organic compounds which inhibit biological systems.
The classification scheme used in Table 2-2 involved grouping compounds of
similar structure and characteristics which might tend to inhibit biological
processes at similar concentrations. The reader is cautioned, however, that
chemicals with similar structure do not always possess similar inhibition
characteristics. For a more detailed summary of what is known about inhibition
by individual organics, see Russell, et al. (1983), U.S. EPA (I981a), Geating
(1981), and U.S. EPA, (1977b).
It is important to note that the categories in Table 2-2 are very broad and the
concentration ranges presented are simply typical values for some compounds
and should not be interpreted as defining an inhibition range for all compounds
within the classifications. Appendix B lists the compounds that fall into these
broad classifications.
2.3 SEWER COLLECTION SYSTEM
Industrial and waste hauler discharges can be very detrimental to the condition
of the sewer collection system. The types of substances responsible for such
problems are generally the same pollutants addressed by the specific prohibi-
tions. Table 2-3 defines four categories of these substances with examples given
for each.
-------
Corrosivity problems can be identified by observing the deterioration of the pipe
material or measuring the pH of the wastewater at several locations within the
collection system. Corrosion rates generally increase significantly below pH 5
and above pH 12.5. The best approach is to maintain a program of regular sewer
inspection coupled with the use of recording pH meters located at strategic
interceptor locations in the sewer system. A proper inspection program should
include the detection of unusual colors or odors by trained personnel.
Detecting substances which may result in ignitability or reactivity problems is a
more complicated task. Instrumentation is available to detect explosive
conditions, lack of oxygen and the presence of hydrogen sulfide. Such equipment
is typically used for worker safety prior to entering confined, below grade areas
such as manholes and sewer interceptors. To install and maintain sensitive
instruments of this type, along with the recording devices needed for proper
monitoring, would be very expensive if placed in numerous locations. A more
practical approach is to survey the industries discharging to a POTW as a means
of identifying potential dischargers of these substances (see Section 3). Once
likely industrial candidates are identified, portable detection instrumentation
can be used to spot check the sewer environment or permanent equipment can
be installed in a few, selected locations.
Baltimore, Maryland and Passaic Valley, New Jersey are examples of locations
where sewer collection system problems have been identified and addressed (see
Appendix A). Discharges of volatile organics such as ethyl benzene, xylene,
toluene and tetrachloroethylene (PCE) into the Baltimore collection system have
resulted in pump station and other building evacuations in the past. By
successfully tracing these problems to the source, the City has reduced the
occurrence of such incidents dramatically. Passaic Valley experienced both
sewer clogging problems from a pulp and paper mill and high concentrations of
flammables from a number of industrial sources. Lower explosion limits (LEL)
were established and industries identified as being dischargers of flammables
were required to install LEL detection equipment in their effluent piping.
Another example of the use of LELs is by the Los Angeles County Sanitation
Districts, where the wastewater ordinance requires all significant potential
dischargers of flammable substances to install, operate and maintain an
adequate combustible gas monitoring system. The system provides early
detection so that preventive measures can be taken. Systems must be installed
in a fixed location and continuously operated, incorporating an indicator, as well
as an automatic continuous recorder, adjustable two-stage alarm system,
calibration for methane detection, and a means for diverting flow from the
sewer to a holding vessel when the combustible gas level is 20% of the LEL or
greater. Industrial users, primarily petroleum refineries, storage and transfer
facilities, and chemical manufacturing plants, must submit engineering drawings
of their proposed systems for review and approval by the Districts prior to
construction.
13
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2.4 PLANT OPERATIONS
There are numerous tools available to the plant operator to monitor the
condition and performance of the facility. Suspended growth biological treat-
ment systems generally provide more operational control (such as sludge wasting
and recycle, aeration tank D.O., process modifications), and therefore monitor-
ing opportunities, than do fixed film systems. However, all POTWs have
processes that can be easily checked on a daily basis which can signal the onset
of an interference problem. Making use of the available tools may be the
difference between total process failure and catching the problem before it fully
develops.
The operational tools available fall into the following categories:
• observation
• instrumentation
• analytical results
2.4.1 Observation
Some of the most powerful tools in the operation of a treatment facility are the
senses of sight, sound, touch and smell. Maintenance personnel are typically
trained to listen for the improper operation of a blower or to feel for signs of an
overheated bearing. Similarly, plant operators should be trained to observe
changes in the appearance or smell of unit processes which might be indicative
of a problem. A major thrust of the Hamilton Township, New Jersey, inter-
ference identification program was to require that operators spend a minimum
number of hours each work shift "walking the grounds" {see Appendix A). Such a
requirement can (and did) result in the identification of late night spill events
that might otherwise go unnoticed until morning, when it may be too late for
biological processes to recover.
Examples of what operators should notice as they work around a POTW are the:
• surface appearance of clarifiers
• amount and color of foam in aeration tanks
• presence of nuisance organisms, insects or odors near fixed film
systems
• common odors at each plant location
• sludge and recycle flow appearance at each processing step
The EPA has provided troubleshooting and process control guidance to operators
in previously published manuals (U.S. EPA, 1977a; U.S. EPA, 1978). These
documents assist POTWs in troubleshooting process performance problems, and
provide numerous tables to help the operator identify problems through visual
inspection. Many problems uncovered through plant observation do not result
from industrial discharges, but rather from equipment malfunction, inadequate
maintenance or design deficiencies. The two manuals referenced above provide
assistance in distinguishing between the potential sources of such problems.
Table 2-4 identifies the operational indicators of process malfunction which may
14
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be related to industrial waste discharges. The processes listed in Table 2-4 are
for typical secondary treatment plants. Advanced wastewater treatment
systems and sludge thickening and dewatering processes are not included in this
manual.
2.4.2 Instrumentation
Instrumentation is designed into treatment facilities as an aid to the operations
staff. Whether located at the central control panel or at the piece of equipment
being monitored, digital and dial gauge readouts provide instant feedback to an
experienced operator concerning the conditions in the plant. Strip chart
recorders maintain permanent records of the critical parameters, such as raw
wastewater feed, to identify long-term trends and isolated excursions. Despite
the availability of instrumentation and level of sophistication, much of the
hardware may be unused or simply ignored by operators because of a perceived
complexity and/or unreliability.
When monitoring instruments are incorporated into a POTW, it is important that
such equipment be maintained in accordance with manufacturer's specifications
and recalibrated at regular intervals. The utility of these instruments depends
upon the operator's understanding of the readout. Proper training of operations
personnel is therefore a critical element in using instrumentation as possible
early warning signals of a pending interference problem.
The use of simple portable instruments and equipment for routine POTW site
inspection can be quite useful to the operator. The use of a device to measure
the depth of sludge in clarifiers may be the best way to learn that a sludge pump
did not operate as expected or that unusual wastes have entered the plant. In
the Tolleson, Arizona treatment plant (see Appendix A), the operators discovered
that a rapidly increasing sludge depth in the primary clarifiers was indicative of
upset conditions caused by high solids discharges from a meatpacking industry.
A number of commercially available instruments can be utilized by plant
operators either for permanently-mounted, continuous monitoring and control or
as portable devices. Table 2-5 lists the types of instruments, where they can be
utilized in the treatment facility, and the parameters of interest in interference
identification. The instruments listed Ln the table are useful for both process
evaluation as discussed in this section, and for wastewater monitoring
(Section 2.5). The instrumentation selected by a POTW should be a function of
the wastewater characteristics of the industrial discharges as determined by the
industrial survey conducted during pretreatment program development.
2.4.3. Analytical Results
The subsection on observation (2.4.1) outlined the benefits of noting the smell
and appearance of unit processes during routine plant inspections. There are a
number of standard analytical techniques that can be used to confirm the
presence and extent of problems identified by sensory observation. Table 2-6
lists the common test procedures that can be performed on typical treatment
plant processes. The testing frequency indicated is typical of well-operated
15
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facilities. The actual frequency used will be site-specific as a function of
process problems, industrial discharges, and staff and equipment availability.
The monitoring procedures listed on Table 2-6 are relevant to assessing overall
plant performance, not just interference problems. As was the case in both
Tolleson, Arizona (primary sludge depth) and Oswego, New York (activated
sludge SVI), the relationship between operating parameters and specific
industrial discharges is oftentimes correlated by trial and error.
Conductivity, D.O., flow and pH are the parameters that are measured most
reliably by the instrumentation specified in Table 2-5. Some of the devices,
such as the selective ion electrodes, are adversely affected by the wastewater
environment, and are therefore not well-suited to on-line monitoring
applications. TOG analyzers are expensive instruments that should be housed in
controlled laboratory environments. In order to be effective in identifying slug
discharges of organics, the instrument must be provided with representative
wastewater samples on a regular basis.
2.5 WASTEWATER MONITORING
A. critical aspect to any successful industrial waste management program is
comprehensive monitoring of industrial discharges, POTW influent, effluent and
sludge, and important process streams within the plant. The benefits derived by
the municipalities in terms of understanding their influent wastewater charac-
teristics and sources of specific contaminants are many. Monitoring is also
performed to provide data from which to develop local limits and later to
evaluate an industry's compliance with those limits.
Developing a large database of analytical results on a POTW's wastewater
provides a baseline for future comparison. When industrial discharges cause a
significant deviation from the baseline, noting such changes will help detect a
potential interference problem and may prove useful in later identifying the
source. In the Hamilton Township, New Jersey plant, the discharges from a
pharmaceutical manufacturer were correlated to high POTW influent soluble
BOD through an extensive analytical testing program. A pharmaceutical manu-
facturer was also implicated in the discharge of high ammonia levels to the
Neuse River Plant in Raleigh, North Carolina. Year-round sampling of 70 metal
finishing/electroplating industries and strict enforcement of local limits for
metals has substantially reduced the concentrations of heavy metals (Cr, Cd,
Cu, Pb, Ni, Zn) at the Metro-West Point Plant in Seattle, Washington over the
past five years.
2.5.1 POTW Influent
Most municipalities now have some form of influent wastewater monitoring. The
most common approach is to install an automatic sampler at the headworks of
the plant. State-of-the-art sampling equipment provides the POTW with four
options:
16
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t timed sampling with collection in discrete sample containers
• flow-proportioned sampling with collection in discrete sample
containers
• time-proportioned composite sampling
• flow-proportioned composite sampling
Samples collected in discrete containers provide a means of identifying diurnal
fluctuations in wastewater characteristics. Such an approach can be costly if
hourly samples are analyzed, but is particularly useful if "midnight dumping" of
prohibited substances is suspected, since discrete samples do not mask the
impact of short-term discharge concentrations by averaging over a Z4-hour
period. An alternative approach is to preserve and store the discrete samples,
and then analyze only if problems occur at the POTW.
Composite sampling involves the collection of a fixed volume of wastewater at
regular intervals into a single, large container. A typical approach is to collect
100 ml every 15 minutes for 24 hours into a 10-liter sample bottle. This is the
most common method of obtaining average daily influent samples. A better
approach is to proportion the sample volume consistent with the influent
volumetric discharge at the time nf collection. This technique requires a
feedback signal from an influent flow meter to the sampler, but results in a
sample that is consistent with the mass loadings to the POTW.
Analyses performed on a POTW influent should routinely include BOD, SS and
other pollutants (such as NH3 and P) included in the NPDES permit. When
evaluating the potential for inhibition caused by toxic pollutants, additional
testing is necessary. The testing intervals for the toxic organics and metals are
determined on a site-specific basis as a function of permit violations,
pretreatment program requirements, process upsets, types of industrial
discharges and budgetary constraints.
A suggested approach is for the POTW to survey its nondomestic users to find
out what toxic metals and organics are reasonably expected to be present in its
influent at detectable levels. The POTW should then analyze its plant influent
for those pollutants. In addition to the pollutants expected to be present, it is
recommended that the POTW sample for the metals and cyanide listed in
Table 2-1. Among the toxic organic pollutants, standardized analytical methods
are available primarily for EPA's list of "priority pollutants". These pollutants
are covered by EPA methods in the 600 series. The reference for these methods
is the Federal Register (40 CFR Part 136), October 26, 1984, and June 30, 1986.
Most full-service commercial analytical laboratories, as well as some of the
large municipal laboratories are capable of analyzing for the priority pollutants.
A once per year scan for the priority pollutants is recommended. For pollutants
which are detected in the influent at least once, additional sampling should be
conducted to determine variability and evaluate trends.
2.5.2 Other POTW Locations
effluent is generally composite sampled and analyzed in accordance with
NPDES permit requirements. Operators may, however, select other process
17
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streams within a facility for intermittent monitoring. For example, sampling
primary effluent allows for calculations of loadings to the secondary treatment
system. The response of a biological process is more easily explained if one
knows the specific wastewater feed characteristics, as opposed to assuming a
primary clarifier performance based on influent characteristics.
POTW sludge monitoring is necessary to determine if the POTW is meeting
applicable sludge use or disposal requirements and to detect sludge
contamination. If sludge contamination is found, it will trigger the need for
additional sampling of both domestic wastewater and nondomestic discharges in
order to identify the source(s) of contamination.
An informative yet infrequently employed sampling method is to evaluate the
strength of sidestream flows, particularly from solids processing. Recycle flows
can add 50 to 100 percent of the influent solids and organics to the liquid
processing trains when inefficient sludge solids capture persists. POTW design
often neglects the impact of recycle streams, a problem magnified when
unanticipated quantities of heavy metals and priority organics are discharged
from industrial sources. While monitoring such sidestreatns on a daily or weekly
basis may prove impractical (and costly), periodic sampling and flow measure-
ment permits mass balancing around solids processing units, and can provide
insight into the presence of substances in the POTW effluent not necessarily
present in the influent.
Recycle flows can be intermittent, or at least shift dependent, and as such are
poor candidates for 24-hour composite sampling. Grab sampling is done by
extracting a representative sample of sufficient quantity to perform the
necessary analytical tests. Some procedures, such as the extraction methods for
oil and grease, require grab sampling to prevent deposition of the material on the
container over the 24-hour composite period.
2.5.3. Inhibitory Effects Testing
Testing which measures the inhibitory effects of industrial discharges might
prove useful in evaluating the impacts of those discharges on the POTW. One of
the simplest methods of detecting inhibition due to an industrial discharge is to
add incremental volumes of the waste to seeded dilution water and analyze for
5-day BOD. If the wastewater is inhibitory to the POTW bacteria, higher
concentrations will result in less oxygen depletion and lower BOD. If completely
biodegradable, larger volumes of the industrial waste should produce
proportionately higher oxygen depletion. The advantage of this technique,
termed serial addition, is that the concentration at which the waste changes
from biodegradable to inhibitory can be estimated by this technique. The major
disadvantages are the five day waiting period and the questionable correlation
between degradation in a BOD bottle as compared with a full-scale biological
reactor.
Other test procedures have been developed which overcome some of the
disadvantages of the BOD procedure. One such procedure is to add varying
concentrations of an industrial wastewater to a BOD bottle containing an active
-------
biological culture (usually mixed liquor activated sludge) from the secondary
treatment system. A DO meter equipped with a BOD probe can be used to
measure the oxygen uptake rate after the sample is saturated with oxygen. If
the industrial wastewater is inhibitory, increased doses will result in reduced
oxygen utilization. A similar approach using respirometers allows for the use of
larger reactors (up to 10-liters), continuous oxygen feed and strip-chart
recording of the uptake rate with time. At the Patapsco Wastewater Treatment
Plant in Baltimore, Maryland (see Appendix A) daily routine operation of a
respirometer is used as a tool for measuring the inhibitory characteristics of the
plant influent. The standard operating procedure for the respirometer involves
the use of plant biomass and simulates the plant's biological system (Slattery,
1986).
Recent variations of the respirometry approach utilize special cultures of
microorganisms, instead of the POTW bacteria, as more precise predictors of
toxic effects. One manufacturer uses specially prepared and packaged bacterial
cultures in conjunction with a DO meter to plot families of inhibition curves and
to develop lethal concentration dosages analogous to those obtained by bioassay
testing. A second technique uses photo-luminescent marine microorganisms,
whose light output decreases proportionally to the level of toxic shock when fed
varying concentrations of industrial wastewater. This approach has been used
extensively in Baltimore, Maryland (see Appendix A) and Chattanooga, Tennessee
to evaluate the toxicity of influent wastewaters to the POTW and to measure
toxicity reduction through the biological treatment process. At the Patapsco
plant in Baltimore, pure oxygen activated sludge treatment reduced the
wastewater toxicity by up to 40 percent from the raw wastewater feed.
A summary of the methods available to measure biological inhibition is presented
in Table 2-7. The table also includes some cost, testing and training time
estimates, of concern to municipalities developing a program for determining
inhibitory effects of industrial or waste hauler discharges. A potential problem
with all of the techniques discussed is that the results do not accurately reflect
the treatability of the wastewater if the biological treatment populations
become acclimated to the industrial waste over a long period of exposure.
19
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TABLE 2-1
METAL, CYANIDE AND INORGANIC COMPOUND CONCENTRATIONS
INHIBITING BIOLOGICAL PROCESSES
(in mg/1)
Biological Process
Pollutant
Ammonia
Arsenic
Boron
Cadmium
Calcium
Chloride
Chromium (Tot.)
Copper
Cyanide
Iodine
Iron
Lead
Manganese
Magnesium
Mercury
Nickel
Silver
Sodium
Sulfide
Tin
Vanadium
Zinc
Activated
Sludge
^480
0.04 - 0.4
0.05 - 10
0.5 - 10
2,500
N/A
0.1 - 20
0.1 - 1
0.05 - 20
10
5 - 500
0.1 - 10
10
N/A
0.1 - 5.0
1 - 5
0.03 - 5
N/A
>50
N/A
20
0.30 - 20
Nitrification
N/A
N/A
N/A
5-9
N/A
180
0.25 - 1
0.05 - 0.5
0.3 - 20
N/A
N/A
0.5 - 1.7
N/A
50
2 - 12.5
0.25 - 5
0.25
N/A
N/A
N/A
N/A
0.01 - 1
Aerobic
Fixed Film
N/A
290
N/A
5-20
N/A
N/A
50
25 - 50
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Anaerobic
Digestion
1,500-3,000
0.1 - 1
2
0.02 - 1
N/A
20,000
1.5 - 50
0.5 - 100
0.10 - 4
N/A
5
50 - 250
N/A
1,000
1,400
2 - 200
N/A
3,500
50- 100
9
N/A
1 - 10
N/A - Not Available
Sources: U.S. EPA (1981a), Russell, et al. (1983), Geating (1981) and U.S.
EPA (1986a).
20
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TABLE 2-2
ORGANIC COMPOUND CONCENTRATIONS
INHIBITING BIOLOGICAL PROCESSES
(in mg/1)
Compound Type
Agricultural Chemical
Common Pesticides
Lindane
Aromatics
Chlorinated Benzenes
Nitrogen Compounds
Oxygenated Compounds
Alcohols
Acids
Phenol
Chlorophenols
Nitrophenols
Methylphenols
Phthalates
Polynuclear Aromatic
Hydrocarbons
Activated
Sludge
0.05 -0.10
5-10
5 - 150
0.1 - 5
150-250
1 - 500
1ZO- 500
1,000
N/A
90 - 1,000
5 - 100
50 - 200
N/A
>10
500 - 2,500
Biological Process
Nitrification
N/A
N/A
N/A
N/A
< 0.1 - 18
0.1 - 100
N/A
N/A
N/A
1 - 10
N/A
150
5-50
N/A
N/A
Anaerobic
Digestion
N/A
N/A
100 - 870
0.1 - 1
0.1- 100
5-500
20 - 1,000
N/A
10
100- 200
0.2 - 100
100
N/A
N/A
N/A
N/A - Not available
Principal Sources:
Russell, et al. (1983), U.S. EPA (19?7b), U.S. EPA
(I981a), Geating (1981), U.S. EPA (1986a)
21
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TABLE 2-3
WASTE CHARACTERISTICS PERTAINING TO
HAZARDS IN COLLECTION SYSTEMS
(From Busch, 1986)
Term Description Examples
Ignitability Pose a fire hazard - Gasoline
- Industrial solvents
Corrosivity Corrode standard - Acids
construction materials - Caustics
Reactivity - Spontaneous reaction - Calcium carbide
(Explosivity) with air or water - Cyanides
- Pose explosion hazard - Sulfides
- Generate toxics - Industrial solvents
- Petroleum
hydrocarbons
Fume Toxicity - Build up of toxic fumes - Metals
- Pose a hazard to human health - Pesticides
- Industrial solvents
(benzene, toluene)
22
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TABLE 2-4
INTERFERENCE IDENTIFICATION THROUGH PLANT OBSERVATION
Process
Observation
Possible Cause
Primary Clarification
Activated Sludge
- Aeration Tank
- Clarjfier
Black/odorous waste water
Scum overflow
Low solids content of sludge
Excessive air rates to maintain D.O.
Low density sludge
White, billowy foam
Dark-brown sudsy-foam, black mixed
liquor
Pin floe in overflow
Ash-like material floating on surface
Straggler floe (< 1/4" dia) in
supernatant
Cloudy supernatant, poor settleability
Sludge rising throughout tank
Inadequate pretreatment of waste
Inadequate pretreatment of waste
Hydraulic overloads
Organic overloads
Acid waste, low influent pH, nutrients
Toxics (metal, bacteriocides)
Organic overloads, anaerobic
conditions
Toxic shock load
High grease content of
mixed liquor
Changing organic loads
Increased organic loads, toxic
shock loads, low nutrients
Low D.O. or low pH (<6.5) in
aeration tank
Source: U.S. EPA (19?7a), U.S. EPA (1978)
Z3
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TABLE 2-4 (Continued)
INTEFERENCE IDENTIFICATION THROUGH PLANT OBSERVATION
Process
Observation
Possible Cause
Trickling Filters
- Filters
- Clarifier
Lagoons
Rotating Biological
Contactors (RBC)
Localized rising sludge
Sludge clumps and hubbies rising
to surface
Surface ponding
Odors
Slime colors
Increased effluent suspended solids
Poor effluent quality
Odors
Poor effluent quality
Excessive sloughing
White, stringy biomass
Odors
Organic overloads in aeration tank
Septic conditions
Organic overloads, excessive
biological growth
Organic overloads, anaerobic
conditions
Metals, toxic shock
Excessive sloughing due to pH or
toxic shock loads
Organic overloads, toxic shock
Low D.O., sulfides
Organic overloads, poor pH
conditions
Toxic shock, pH fluctuations
First stage organic overloads, sulfides
Septic influent, sulfides
24
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TABLE 2-4 (Continued)
INTEFERENCE IDENTIFICATION THROUGH PLANT OBSERVATION
Process
Observation
Possible Cause
Anaerobic Digestion
Aerobic Digestion
Rot ton cjjg odor
Rancid butter odor
Poor supernatant quality
Foam in primary supernatant
Sludge temperature drop
Scum blanket too thick
Excessive foaming
Odor
Organic overloads, sulfules
Toxic shock (metals, ammonia)
Organic overloads, toxic shock
Organic overloads
Hydraulic overloads
High grease content
Organic overloads
Low D.O., organic overloads
25
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TABLE Z-5
INSTRUMENTATION OF PLANT PROCESSES
AND WASTE STREAMS
Instrument
Locations
Parameters Measured
Conductivity Meter
Density Meter
gamma radiation
ultrasonic
D.O. Meter
membrane electrode
Flow Meter
flume, venturi,
magnetic, weir
Gas Analyzers
Oxidation-Reduction
Potential (ORP) Meters
pH Meter
Selective Ion
Electrodes
Total Organic Carbon
(TOO Analyzer
Industrial discharge
Primary effluent
Final effluent
Aeration basins
Clarifier underflow
Conditioned sludge
Anaerobic digesters
Aeration basins
RBC stages
Final effluent
Raw wastewater
Sidestrearn flows
Return/waste sludge
Chemical feed
Final effluent
Collection system
Confined spaces
Aeration basin off-gas
Industrial discharge
Primary effluent
Industrial discharge
Collection system
Raw wastewater
Aeration basins
Anaerobic digester
Final effluent
Industrial discharge
Primary effluent
Final effluent
Industrial discharge
Raw wastewater
Primary effluent
Final effluent
Metals,
Dissolved solids
MLSS
Solids concentration
Dissolved oxygen,
Flow rate
CO, CO2, CH4, H2S
Oxygen transfer
Metal forms
Acids, Bases
Cl", CN~, Cu+, Cut+, F",
NH3, NO', Pb++, S
Organic slugs,
oil and grease
Source: James M. Montgomery, Consulting Engineers, Inc.
26
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TABLE 2-6
ANALYTICAL MONITORING OF PLANT PROCESSES
Process
Parameters
Testing
Frequency
Clarification
Activated Sludge
Trickling Filters
RBCs
Anaerobic Digestion
Dissolved oxygen
Sludge solids content
Sludge blanket depth
Dissolved oxygen
Mixed liquor suspended solids
Oxygen uptake rates
Microscopic examination
Nutrients
Sludge volume index
Slime thickness
Influent pH, temperature, H£S
Effluent solids content
Dissolved oxygen (each stage)
Soluble BOD (each stage)
Biomass thickness
Shaft weight
Effluent solids content
Temperature
Solids content
Metals content
Volatile acids/alkalinity
Supernatant solids, NHg
Methane content of gas
Daily
Weekly
Daily
Daily
Daily
Daily/Weekly
Daily/Weekly
Daily/Weekly
Daily
As needed
As needed
As needed
Daily
Weekly
As needed
Daily/Weekly
As needed
Daily
Weekly
Weekly/Monthly
Daily
Weekly
Daily
Source: James M. Montgomery, Consulting Engineers, Inc.
27
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TABLE 2-7
METHODS FOR EVALUATING INHIBITORY EFFECTS
OF INDUSTRIAL WASTEWATERS
1.
2.
3.
4.
Method
BOD Serial Addition
Respirometry
Packaged Bacteria
Photo Luminescense
Testing Time
5 days
30-60 min.
30-60 min.
15 min.
Approximate
Equipment Costs
$1,000
$1,000 - $5,000
$1,000 - $2,000
$5,000 - $10,000
Operator
Training
2-4 hrs.
4-8 hrs.
4-8 hrs.
20-40 hrs.
Source: James M. Montgomery, Consulting Engineers, Inc.
28
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3. SOURCE IDENTIFICATION
There are two aspects of source identification that should be considered by
POTWs when investigating interference problems:
• specific causative pollutants
• industrial source(s) of the pollutants identified
The ease with which a causative agent is identified depends upon the nature of
the permit violation. For example, if the interference results from the inability
to dispose of sludge, the problem nearly always results from an unacceptable
concentration of a particular heavy metal. However, if the plant effluent has a
BOD above the permit limit, the problem can range from a shock loading of
influent BOD to an inorganic or organic pollutant that is toxic to the biological
population in secondary treatment. Isolated spill events are difficult to trace to
a specific pollutant unless the pollutant is detected in routine influent and
effluent screening or the spill is accompanied by distinct, recognizable odors,
appearance, pH or solid residues. Recurring discharges may be linked to a
substance with time by process of elimination and analytical testing.
Once an interference is linked to a specific pollutant, the next step is to identify
the industrial source. If the POTW has sufficiently charcterized its industrial
users as part of its initial pretreatment program development, this task will be
greatly simplified. As part of the development of a federally-approved pretreat-
ment program, POTWs are required to conduct a survey of industrial users to
characterize their wastes. The POTW should be familiar with each lU's
industrial processes and the chemicals which are used, produced, stored,
disposed, or otherwise handled on the site. The potential for intentional or
accidental discharge of pollutants should be evaluated. The IU survey informa-
tion should be updated at least annually. Another approach to identifying
industrial sources is a tracking program that monitors the interfering pollutants
at key interceptors and traces the substance back to its discharge point.
While industries are sometimes responsible for POTW permit violations, the fault
can be with operation and maintenance practices at the POTW. Where plants
experience chronic operational problems that cannot be linked to industrial
waste discharges, the plant staff may wish to conduct a Composite Correction
Program (U.S. EPA, 1984) to identify operational problems. If violations persist,
then a more comprehensive search for industrial sources is justified. The CCP
was developed by the U.S. EPA as a means to provide "information on methods tc
economically improve the performance of existing POTWs". It outlines an
approach for POTW personnel to evaluate POTW operations and implement
systematic improvement steps.
29
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3.1 CHRONIC DISCHARGES
Industrial waste monitoring is the key to successfully identifying most chronic
industrial waste sources. Industries should be monitored for conventional
pollutants, with the testing of other compounds determined by the nature of the
specific industrial waste. In the case of categorical industries, some substances
of concern and pretreatment requirements are already specified by the
regulations. For noncategorical industries, information such as permit
applications and questionnaire responses or specific analytical testing of industry
effluent should provide sufficient data to establish a monitoring program.
Sewer use ordinances and industrial waste management programs typically
provide for some means of monitoring an industry's discharge to the municipal
collection system. Such ordinances require measurements of both quantity and
quality of the industrial or combined domestic/industrial flow. Industrial
discharges are usually monitored both by industry, with regular self-reporting
requirements, and by the municipality.
If it has been determined that a plant upset is being caused by industrial wastes
and is not a result of other POTW deficiencies, then it is up To POTW personnel
to identify the specific source of that upset. This may necessitate expansion of
the POTW's monitoring program as discussed in the next subsection. POTWs
experiencing interference problems tend to fall into one of three categories
regarding interference:
1. A single major industry in town dominates the waste characteristics
at a relatively small POTW.
2. One or two industries among several are primarily responsible for
waste strength fluctuations in small to medium-sized POTWs.
3. Industrial wastewater from numerous sources controls the waste-
water feed characteristics, with no single dominant industry.
The first category listed above is by far the easiest situation to deal with from
an identification standpoint. By monitoring the industry's discharge, POTW
influent and effluent and other relevant plant operations, the impact of the
industrial waste on the POTW can be determined. The cities of Oswego, New
York and Tolleson, Arizona are examples of small facilities significantly
impacted by a single industry.
Category two is a more difficult interference to trace. A monitoring program
may be sufficient if a large database exists covering a period of time.
Unfortunately, when numerous industries must be tested on a frequent basis, the
sampling and analysis costs can be high. Routine sampling for all industries with
additional sampling for troublesome industries may provide a solution for some
POTWs. For example, Paris, Texas set up a comprehensive short term (90 day)
sampling program that industry supported financially. Through this effort, Paris
was able to distinguish which industries were likely to be problems and then
could adjust their long-term sampling accordingly.
30
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The third category generally applies to larger facilities which are less likely to
be susceptible to any particular industrial effluent. Baltimore, Maryland and
Passaic Valley, New Jersey are examples of facilities which fit into this third
category, but have experienced interference (see Appendix A). Large plants may
be less likely to experience permit violations due to industrial waste, but they
have frequently experienced inhibition and other operational and maintenance
problems. Intermittent discharges are particularly difficult to pinpoint by POTW
personnel because of large service areas.
3.1.1 Routine Monitoring
In order to have the ability to utilize POTW influent characterization to identify
the source of interfering pollutants, adequate background and supporting infor-
mation must be available to POTW personnel. A database obtained over several
years of routine monitoring enables a POTW to develop action level criteria for
key parameters. When monitoring shows that these criteria have been exceeded,
it can be suspected that a spill or unauthorized discharge of industrial waste has
occurred, which triggers a tracking program. Specific details of industrial
monitoring programs have been outlined by EPA and others (EPA, 1983; WPCF,
1982).
Routine compliance monitoring, which is part of any local industrial waste
control program, will sometimes serve to generate an adequate background
database. However, POTWs which have interference problems may need to
perform additional monitoring until the source of the problem can be identified.
For compliance monitoring purposes, monitoring methods and frequency are
generally specified by each municipality in its pretreatment program documents
or sewer use ordinance and in discharge permits, contracts or orders issued to
industrial users. Self-monitoring by industry with monthly checking by the
municipality enables the POTW and the industrial users to share the expenses of
monitoring. Such an approach is most successful when:
key manholes or representative sampling points are available
sampling procedures are clearly outlined and followed
a qualified laboratory performs the analytical testing
rigorous reporting requirements are established for the industries
spot checking by the municipality is performed on a frequent yet
random basis
The alternative to self-monitoring is for a municipality to perform all sampling
and analytical services on a once-per-month or once-per-quarter basis, depending
on the significance of the specific industry to the POTW. Under this scenario,
split samples should be made available to the industry, if requested, to provide
them with the opportunity to verify the test results from which their compliance
status and user fees will be determined. Many municipalities prefer not to place
major reliance on industrial self-monitoring for compliance determinations; they
are able to recover the costs for their monitoring programs by assessing fees for
industrial discharge permits or by directly billing the sampling costs to the
industrial user.
31
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Regardless of the approach taken, the objective of any industrial monitoring
program is to obtain representative analytical results of the wastewater flow and
characteristics. An industry with highly variable quality and quantity should be
sampled more frequently than one with a consistent effluent quality. An
appropriate sampling schedule or discharge schedule for batch processes should
be determined for the industry.
If industrial wastes have been well characterized and adequately monitored, then
the identification of an interfering or potentially interfering pollutant source
will be facilitated. As an example, if a POTW suspects a change in their influent
wastewater characteristics by observing a change in one or more operational
parameters, this triggers influent sampling. The interfering pollutant and
concentration are determined through analytical testing, which is then compared
with the information from the monitoring database to identify industries that
discharge (or have the potential to discharge) the problem pollutant. In some
cases, especially large sewer systems, it is not easily determined which of many
industrial contributors is responsible for a particular pollutant that is causing an
interference. However, several large POTWs including Baltimore, Maryland and
Hampton Roads, Virginia have experienced success after setting up their
monitoring programs. It has even been suggested that the mere fact that they
set up a program motivated some industries into cleaning up, rather than risking
the consequences. Those large POTWs that have put effort into their monitoring
program have been successful.
3.1.2 Tracking Program
A tracking program is a procedure developed for locating the source(s) of a
pollutant or impact which has been identified at a POTW. Depending on the size
of the POTW, the sewer system and the type and number of industrial users, this
procedure may be very simple or rather complex, A small system with only a
few industrial contributors will probably not require anything more than a
procedure for comparing POTW influent sample characteristics with industrial
monitoring results. On the other hand, large systems may require sophisticated
programs involving computer analysis.
The City of Baltimore has a computer program that attempts to trace
contaminants back to the source, knowing the necessary background data (see
Appendix A). Batch printouts, called the "Daily Average Mass Discharge
Reports," provide monthly listings of companies grouped by sewer service area
and chemicals used, stored, and/or discharged. If a chemical compound (such as
a solvent) can be identified by the tracking team, or later by means of sample
analysis, a search of the Data Management System's batch printouts can identify
possible industrial sources.
Rapid toxicity testing procedures may become valuable tools for identification
of interference sources as they gain acceptance by municipalities. A toxic
impact can be traced upstream through a collection system very rapidly when
the test procedure takes less than 30 minutes. Such a system has been used at
Baltimore's Patapsco Plant to identify influent toxicity problems. This approach
to interference tracing is most useful if the troublesome industry discharges
3Z
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toxicants. Municipalities must continue to rely on more conventional monitoring
practices for upsets resulting from non-toxic contamination.
One of the most comprehensive tracking programs is maintained by the Hampton
Roads Sanitation District (HRSD) in the Tidewater area of Southeastern Virginia.
The HRSD operates nine treatment plants handling 130 million gallons per day
generated over a service area covering 1,700 square miles. Industrial wastes
from 300 sources are dominated by military installations, with other significant
discharges from manufacturing and food processing. Industrial discharges are
categorized according to which of the following methods of tracking is
employed:
• sensory observations
• measurements with field equipment
• sampling and analysis
For the first two types of tracking methods, the HRSD has personnel on stand-by
duty supplied with radio equipped vehicles and extensive field sampling and lab
equipment capable of qualitative, as well as quantitative, analyses. Tracking
begins by HRSD personnel checking pump stations and sewer lines in a
downstream to upstream fashion until the source is isolated. Along the way
samples are collected, labeled and preserved as evidence.
For the third type of tracking method, automatic sampling equipment is set up at
key locations throughout a service area. The samples are collected each day and
analyzed. After pollutant concentration trends are determined, the samplers are
moved upstream. This general procedure is continued until the source of the
problem is found.
In either case, once the source(s) is located, the industry is contacted directly
and actions taken appropriate to the circumstances. All costs associated with
the investigation, clean-up and any other item are billed directly to the source.
The HRSD has found that just by having a highly visible industrial waste
investigative team, users are deterred from unauthorized discharge to the sewer
system. As a result, incidences have decreased by more than 50 percent in the
last eight years.
Tracking programs such as HRSD's are most successful at tracking chronic
discharges. Although not as easily accomplished, isolated spills and unauthorized
slug discharges of short duration can be tracked if quick, aggressive action is
taken. The next section discusses isolated spills in more detail.
3.2 ISOLATED SPILLS AND UNAUTHORIZED DISCHARGES
Interference-causing materials frequently enter POTWs as spills and
unauthorized discharges. The sources generally fall into one of the following
categories (Busch, 1986):
• transportation accidents or leaks
• storage tank or transfer pipe leaks
• industrial discharges
33
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• industrial accidents
• fires in warehouses and commercial operations
• waste haulers
• midnight dumpers
The focus of this manual is on industrial discharges, industrial spills, and waste
hauler discharges fboth legal and illegal), because these are the problems over
which the POTW usually has the most control. However, POTWs may be able to
control some of the other problems listed by extending the spill prevention and
control plan procedures described in this manual to any business that has toxic or
hazardous materials on site. The POTW would have to assess its legal authority
to set up this type of comprehensive program.
The extent of the spill and illegal discharge problem in POTWs is severe. In the
spring of 1985, the Association of Metropolitan Sewerage Agencies (AMSA)
surveyed 107 of their member municipalities concerning hazardous waste
discharges to their facilities. The respondents to the survey represent
308 POTWs, corresponding to 39 percent of the estimated total flow and
47 percent of the estimated industrial flow nationwide. The results of the survey
indicated that hazardous wastes, if improperly discharged, can have serious
effects on POTWs. Specifically, the survey showed:
• nearly all POTWs receive hazardous wastes
• the most commonly discharged wastes are corrosives, solvents,
electroplating baths and sludges
• the most commonly reported sources of these wastes are spills,
illegal discharges from industries and routine discharges from indus-
tries
• half of the respondents indicated the discharge of explosive or
flammable materials (gasoline, toluene, naphthalene, benzene,
xylene, jet fuel) and nearly half reported corrosion of the sewer lines
due to acids and hydrogen sulfide gas
• approximately 30 percent of the respondents have experienced one or
more biological treatment system upsets since 1980 resulting from
the presence of metals, cyanide, diesel fuel, toluene, paint thinner or
stripper, iodine, thiocyanate and pesticides
It is clear that slug discharges resulting from spills, batch releases, dumps, and
illegal discharges are a common concern for many POTWs. It is the responsibi-
lity of industry to notify a POTW of a slug discharge under federal regulations
(40 CFR Part 403.1Z(f)). The regulations describe a slug loading as any pollutant,
including oxygen-demanding pollutants (BOD, etc.),.released in a discharge at a
flow rate and/or pollutant concentration which will cause interference at the
POTW. However, POTWs do not always receive proper notification. One POTW
(HRSD) has responded to slug loads by contacting its major industries in the
service area immediately upon detection. This action is taken for the following
reasons:
34
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1. an IU may not be aware that it is causing a problem;
2. it brings the problem to industry management attention;
3. it provides visibility for the POTW's control program;
4. it discourages illegal discharges;
5. if the problem is later tracked to an industry, the fact that the
industry was notified of the problem immediately may stengthen
enforcement proceedings against an uncooperative industry; and
6. there may still be time to correct the problem.
The mitigation efforts described in Section 4 related to industrial spills focus
mainly on prevention measures and in-plant corrective measures that are best
implemented if proper notification is received by the POTW. The use of
permanent gas detection equipment in sewer lines or treatment plant headworks
is a method of detecting certain types of pollutants that does not rely on
industry notification.
Tables 3-1 and 3-2 provide some examples of industrial spill incidents as
documented by Busch (1986) and Attachment 2 of the AMSA survey report.
3.2.1 Hauled Wastes
Identification of a waste hauler as the source of an interference is sometimes a
difficult task. Hauled wastes can be discharged to convenient manholes and the
hauler gone before the waste reaches the POTW. There are examples where
hazardous waste haulers have paid industries for the seclusion their facility
provides during such illegal discharge events. Approaches used to help alleviate
the problem include:
• periodic sampling of suspected sewer lines
• surveillance of waste haulers and suspected discharge points
• education of industries concerning the seriousness of these violations
• increased public awareness of illegal dumping
• increased enforcement
Many states have enforcement programs to assist POTWs in detecting illegal
discharges. Local law enforcement officials can also be requested to assist in
surveillance activities and enforcement. Video surveillance of suspected
manholes or storm drains is also a nossible option. Some POTWs use locking
manholes to discourage illegal dumping at suspected sites.
Table 3-3 gives examples of the impacts of hauled wastes on both the collection
system and treatment plant in cities identified through the AMSA survey. A
number of problems indicated by the AMSA survey showed the source as
"unknown", which is indicative of the problems associated with tracking hauled
waste interferences. In the Louisville, Kentucky example given in Table 3-3, the
waste hauler discharged the hexachloropentadiene to a manhole located within a
tobacco warehouse (Busch, 1986).
35
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Interference can also occur when hauled wastes are discharged legally to
treatment plants. POTWs that accept discharges of hauled waste should
establish control procedures to ensure that the wastes are compatible with
treatment processes. Procedures for regulating waste haulers are discussed in
Section 4. Identification of a waste hauler as the source of interference can be
facilitated by employing such measures as:
• restricting hauled waste disposal to designated, monitored sites in the
collection system or at the treatment plant
• permitting waste haulers
• requiring submission of a tracking form that documents the origin,
transportation, and disposal of the waste
• sampling hauler loads (samples only analyzed if there is a plant
impact)
• permitting, sampling, and inspecting the waste generator
Submission of a tracking form, called a waste manifest, is already a federal
requirement when haulers are discharging hazardous wastes. The Resource
Conservation and Recovery Act (RCRA) places requirements on hazardous
wastes received by truck, rail, or dedicated pipeline into POTWs. It is important
that POTW operators become aware of these RCRA requirements and the need
to coordinate their local procedures for accepting hazardous wastes with State
and EPA personnel. To provide information and guidance on the RCRA
hazardous waste requirements and their implications for POTWs, EPA has
published a manual titled RCRA Information on Hazardous Wastes for Publicly
Owned Treatment Works (EPA, 1985c).
3.3 RAPID SCREENING TECHNIQUES
Once an interference is suspected, a number of rapid chemical tests, available
from chemical supply houses, can provide preliminary indication of the presence
of substances thought to be producing the interference. These tests help
determine in seconds the need for more thorough quantitative analysis and
tracking. In addition, these screening tests are also useful when evaluating the
loads of waste haulers at dumping stations (Section 4.Z.4).
1. Metals — Chemical test strips utilizing color change indicators may
t-a used to detect the presence and concentration of specific metals.
Z. Solvents — Gas detection tubes, sensitive to gases and vapors, can
indicate the presence and concentration of solvents, but may not be
reliable for determining the specific solvent type due to chemical
interferences among similar-type solvents. A portable hand pump
draws in a calibrated amount of air through the detector tube, and
the amount of color change indicates the concentration.
36
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3.4 SUMMARY
Source identification is the key aspect of any industrial waste management
program. Identifying the source(s) of interference-causing substances being
discharged from a variety of industries is not an easy task and must be
approached with an aggressive, well conceived program if it is to be successful.
There is no simple step-by-step procedure to follow to efficiently identify the
source of every interference problem. However, a rational approach to the
problem can be employed for some interferences which can minimize the effort
required. Figure 3-1 is a flow chart that suggests a possible approach to dealing
with permit violations or upsets. It basically outlines steps to be taken at the
treatment plant to identify possible pollutants causing problems. Figure 3-2 is a
flow chart developed by the HRSD that outlines the steps they take in the event
that the treatment plant is upset or unusual influent is detected. It must be
recognized that each POTW presents a unique management and operations
structure to go along with process variations. Therefore, it is important to
realize that Figures 3-1 and 3-2 are only examples, and not necessarily
applicable to all POTWs. The most important aspects of any source
identification or tracking program are well thought out procedures coupled with
an aggressive approach to enforcement.
37
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TABLE 3-1
INDUSTRIAL SPILLS OF HAZARDOUS MATERIALS:
IMPACT ON SEWER COLLECTION SYSTEM
City
Akron, OH
Bayville, NJ
Bergen, NJ
County
Bloomington, IN
Dayton, OH
Forth Worth, TX
Hillborough, FL
Jacksonville, FL
Los Angeles, CA
County
St. Paul, MN
Toledo, OH
WSSC, MD
Industry
Rubber Mfg.
Pharmaceutical
Water Treatment
Grain Processing
Electroplating
Food Processor
Gasoline Station
Battery Salvaging
Organic Chemicals
Petroleum
Refining
Metal Finishing
Adhesives
Photofinishing
Pollutants
Naphtha, Acetone,
Isopropyl Alcohol
Sulfides from
high BOD
High and low pH
Hexane
Acids
Gasoline
Acids
Solvents
Sulfides
Acids
Glue
Sodium Bisulfite,
low pH
Impact
Explosion
Corrosion
Corrosion
Explosion
Corrosion
Explosion
Corrosion
Corrosion,
Odors
Corrosion
Corrosion
Plugged
Sewers
Corrosion
Sources: Busch (1986), AMSA
38
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TABLE 3-2
INDUSTRIAL SPILLS OF HAZARDOUS MATERIALS:
IMPACT ON TREATMENT PLANT
City
Industry
Pollutants
Impact
Boise, ID
Cam as, WA
Electroplating
Pulp Mill
Cu, Ni, Zn
Chlorine
Reduced
treatment
efficiency
Biological
upset (2 days)
Camden, NJ
County
Dallas, TX
Depue, IL
Dye Mfg.
Organic Chemicals
Fertilizer Mfg.
Aniline Biological
upset, sludge
contamination
Xylene, Toluene Fouled carbon
scrubbers
Sulfuric Acid Biological
process wiped
out
Sources: Busch (1986), AMSA
39
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TABLE 3-3
IMPACTS OF WASTE HAULER DISCHARGES ON POTWs
City
Pollutants
Impact
Central Contra Costa, CA
Louisville, KY
Rockford, IL
San Diego, CA
Solvents
Hexachloropentadiene
Electroplating sludge
Cd, Cr, Pb, Zn, CN~
Gasoline
Biological process
wiped out
Treatment plant
out of operation
for 3 months
Hydrogen cyanide
gas production
potential
Sewer explosion
Source: U.S. EPA (1986a)
40
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IMPROVE
PLANT
PERFORMANCE
TRACE TO
SOURCE
NO
IMPROVE
PLANT
PERFORMANCE
\
NO _ r
\
YES
SAMPLE
•SOUSTfllES -NO
POTW :'
<
FL-cNT
f
SAMPLE POTW
PROCESSES
COMPOSITI COHKCCTIOK
MOQKAM (•((TtXT, »AQI 2«)
SOURCE:
JAMES M. MONTGOMERY.
CONSULTIHa ENOINEEAS, INC.
FIGT3RE 3-1
TREATMENT PLANT UPSET mENTIFICATION PROCEDURES
41
-------
Supervisor inspect*
treatment pltist 1
pbonei key industries
to check iot spills
Source tracked by
sensory or field
observations
Not directly
trackable source
Supervisor contacts
Coast Guard auid,'or
State Water Control
Board if pass*through
is evident
,\
N
Sampler* set up it
key points in the
service are*
Samples collected,
labeled St preserved
during tracking
process
Costs invoiced A
treatrneni plar.t
upset billed :D
industry
Industries in service
area with highest
results sampled
IU permit ck
new monitor
An^ed to reflect
-.3 requirements
f Discharge not
stopped* permit
suspended for up :o
60 days to itop all
industrial waate-
waler discharges
J_
I
rU permit aodified
to reflect compliance
schedule Se possibly
increased monitoring
requirements
and/or
nav ^e terniinated at
th-s tirr.e or later
If discharge still
. not m compliance
i permit revoked
FIGURE 3-2
HRSD SOURCE TRACKING PROCEDURE
4Z
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4. MITIGATION
Mitigating an interference is the goal following the detection of an interference
problem. Whether source identification precedes mitigation depends on the
success of the POTW's tracking program, its knowledge of its lUs, and the other
issues discussed in Section 3. In certain cases, interim measures to address
interference can be taken without initially defining the interfering pollutant
substance or source, although this information can be very helpful. However,
even if an isolated interference event can be handled by process modification at
the treatment plant, the source of the interfering discharge should be identified
and controlled. Interference mitigation by pretreatment and source control or
legal and enforcement remedies obviously requires information about the
discharger(s) causing the problem, but results in a more reliable solution.
The success of any effort to mitigate interference is dependent to a great extent
on the characteristics of the pollutants causing the interference, the charac-
teristics of the treatment plant (capacity, capacity utilization, biological
process, etc.) and the type(s) of mitigation attempted. It is important to
emphasize that mitigation of an interference problem is generally not a
straightforward process. Each POTW possesses unique characteristics that
exclude generalized solutions or approaches so that a combination of techniques
is often necessary to realize satisfactory results.
4.1 TREATMENT PLANT CONTROL
The effects of industrial pollutants on a typical POTW can be eliminated or
minimized through a number of measures initiated at the treatment plant, often
in combination. They can be generally categorized as:
biological process control
biological augmentation
chemical additions
operations modifications
physical modifications
The list above is generally in order of increasing implementation difficulty, e.g.,
biological process control generally requires only minor changes in plant opera-
tion while physical modifications can include costly capital improvements.
4.1.1 Biological Process Control
Biological process control is generally limited to activated sludge systems,
although some modifications to fixed film processes (e.g., trickling filters,
rotating biological contactors) might be considered as a form of biological
43
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process control. An activated sludge system is generally monitored or controlled
by utilizing one or more of three process parameters: mean cell residence time
(MCRT), mixed liquor suspended solids (MLSS) and food to microorganism ratio
(F/M). The biomass and its characteristics are controlled by varying these
interrelated process parameters. The following changes to these parameters
have been observed to mitigate the effects of industrial pollutants on an
activated sludge system:
1. Increase the Mean Cell Residence Time. Increasing the MCRT
{sludge age) has been shown to have the effect of reducing the
inhibitory effects of all forms of toxic industrial contaminants. By
increasing the MCRT at the first sign of a possible toxic upset, (by
decreasing the solids wasting rate) the inhibitory effect of any
toxicant will generally be less than if no action is taken.
2. Increase the Mixed Liquor Suspended Solids. High mixed liquor
suspended solids (MLSS) concentrations have been shown to offset
some of the effects of industrial pollutants. A high MLSS provides
the best conditions for biosorption and acclimation to a toxic
substrate. Increasing the sludge return rate tu the aeration basin at
the first indication of toxic upset, while at the same time diverting
and storing any remaining toxic influent away from the aeration
basins, will lessen the impact of a short term upset and cause quicker
biomass acclimation to a long term problem.
3. Decrease the Food-to-Microorganism Ratio. This parameter is
directly related to both the MCRT and the MLSS. It has been
observed that decreasing the F/M causes improved biodegradation of
toxic comtaminants, and expedites biomass acclimation.
Table 4.1 summarizes these process control steps.
The process control steps described apply to both activated sludge systems
treating for carbonaceous removal and nitrifying systems. Generally, the steps
described are beneficial for treating any type of interfering pollutant, whether it
be a metal, toxic organic or high-strength conventional pollutant.
For a fixed film process, control of the biomass characteristics is not as easily
accomplished. However, varying the amount and point of recirculation in a
trickling filter can modify the inhibitory effect of industrial pollutants.
Recirculating secondary clarifier effluent is a means of achieving the greatest
dilution effect, which may be desirable for high-strength organic waste or
toxics. Should excessive biomass sloughing be a problem due to toxic pollutants,
returning uncontaminated secondary clarifier underflow may help in maintaining
a proper biomass population.
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4.1. 2 Biological Augmentation
Biological augmentation is a method by which selected microorganisms are added
to an existing biological population in an attempt to improve some characteristic
of the biological system. Conclusive evidence is lacking, but biological
augmentation of secondary treatment systems has been reported to improve
some industrial pollutant treatment by promoting the specific microorganism
populations that successfully degrade particular pollutants. Other enhancements
reported include reduced sludge production and increased COD removal rates
(Grubbs, 1986). The addition of selected microorganisms to an aeration basin is
relatively inexpensive and in the worst case will have no effect on treatment.
The EPA, through ongoing experiments at the Wastewater Engineering Research
Laboratory in Cincinnati, Ohio, is presently studying the subject in greater
depth. Maiden Creek, Pennsylvania employed biological augmentation to
improve treatment, however the results of these efforts were clouded due to
other modifications made at the same time (see Appendix A). Rotating
biological contactors plants have used selected bacteria under substrate-limiting
conditions as a control on biomass growth, but with limited success.
a treatment upset has occurred, biological augmentation by reseeding with
viable microorganisms is a useful step in getting a plant up and running quickly.
Having commercially packaged microorganisms available and in supply at a
treatment facility may help in speeding such a recovery if reseeding from
another treatment facility is difficult.
4.1.3 Chemical Addition
The addition of chemicals or nutrients to the wastewater stream in existing
treatment steps has been shown in many instances to mitigate the effects of
some industrial pollutants. The following are examples of chemicals or additives
that have been shown to improve industrial wastestream treatability or
biological process stability:
chlorine
nutrients
lime or caustic
organic polymers
inorganic coagulants
powdered activated carbon
Table 4-2 lists these chemicals and additives, the reasons for their use and the
resulting effects. The reader is cautioned that the generalizations in the table
do not apply to all situations. Some exceptions are pointed out in the text.
Chlorine. Chlorine has been shown to be successful in controlling bulking
activated sludge caused by industrial pollutants from such industries as textiles,
breweries and wood and paper products. Points of chlorine addition vary, but
best results generally occur when chlorine is added to the aeration basin effluent
or return activated sludge (RAS). The Horse Creek Plant in North Augusta,
South Carolina and the East Side Plant in Oswego, New York are examples of
facilities which have successfully employed chlorination to control bulking sludge
(see Appendix A).
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Nutrients. Phosphorus addition and, to a lesser extent, sulfur and nitrogen
addition, occasionally improve biological treatment and sludge settleability of
industrial wastewater with high carbonaceous content. In general, better
treatment and settleability is attributed to correcting a nutrient deficient
condition resulting from a high industrial/domestic wastewater ratio.
pH Adjustment. Lime and caustic are sometimes successful at mitigating the
effects of some heavy metals on activated sludge systems. Addition of either
before primary treatment has the effect of raising the pH which generally
improves precipitation of heavy metals in primary clarifiers. There are
exceptions to this generalization, however. For example, it makes a difference
whether the pH is being raised from 2 to 6 or from 7 to 11. In this latter case,
iron and chromium will go into solution rather than precipitate. Optimum pH
ranges exist for metal insolubilities, but these ranges are affected by many
factors and are therefore system dependent. Lime can also be used for pH
adjustment of an acidic wastewater prior to aeration to provide a more
conducive environment for biodegradation.
Coagulants. Polymers and inorganic coagulants such as alum and ferric chloride
are introduced to POTW wastestreams in part to help mitigate the effects of
industrial pollutants. Added prior to primary treatment, the coagulants improve
primary sedimentation and may increase the removal of toxic pollutants before
they reach the aeration basins. Added after the aeration basins, the coagulant
aids can assist in controlling bulking sludge and reducing effluent suspended
solids. Jar testing is an important part of any chemical addition program as the
best means of determining optimum dosages. The North Shore Sanitation
District in Gurnee, Illinois has utilized coagulants successfully for mitigating the
effects of interference (see Appendix A). It should be noted that chemical
coagulants affect the characteristics of the sludge and could alter ultimate
disposal methods. If added after secondary treatment, they could increase the
toxicity of the recycle sludge. Therefore, their use should be carefully evaluated
and contamination potential should be investigated.
Activated Carbon. The addition of powdered activated carbon (PAC) to an
activated sludge unit has been successful at reducing the inhibitory effect of
toxic organic chemicals. By providing adsorption sites, the organic pollutants
not biodegraded are removed by the activated carbon. The activated carbon also
improves sludge settleability by providing dense floe nuclei. A patented process
(PACT, licensed and sold by Zimpro, Inc) exists employing this treatment
concept at full scale. However, even a slug additon of PAC to an aeration basin
known to contain toxics can significantly reduce the effects of the toxics on the
biomass.
4.1.4 Operations Modification
Activated Sludge Alternatives. A further means of mitigating the effects of
industrial pollutants on POTWs is through modifying the operation of existing
treatment steps. Activated sludge systems are often designed to operate in
several different "modes" (e.g., step aeration, contact stabilization, etc.) by
providing the appropriate physical layout. Some modes of operation have been
shown to be more successful than others at mitigating the effects of industrial
46
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contaminants, particularly those dosed in highly variable concentrations. It has
been shown at the laboratory and plant-scale that extended aeration and step
aeration (step feed) are generally more resistant to upset than complete mix and
conventional activated sludge {see East Side Plant, Oswego, New York,
Appendix A). It appears that complete mix generally provides more consistent
treatment, particularly under shock loading conditions, than conventional plug
flow treatment. The contact stabilization mode is generally less successful at
treating industrial pollutants than other modes, particularly when the organic
matter is predominantly soluble and waste strength fluctuations are common.
Staged Treatment. A successful means of mitigating the effects of industrial
contaminants on any biological treatment process is through the use of staged
treatment. Many treatment systems have realized improved conventional and
industrial pollutant removal when switching from parallel treatment to series
treatment. For example, two aeration basins operating in series are generally
more successful at mitigating the effects of industrial contaminants than the
same two basins operating in parallel. The same principles have been observed
to apply equally to fixed film processes and fixed film/suspended growth
combinations.
Excess Biomass. A typical response of a fixed film process to some industrial
waste stressing is excess biomass growth, resulting in clogged media and reduced
treatment efficiency. Should this be a problem, treatment is generally improved
if the biomass population (thickness) can be reduced. By increasing or altering
shearing forces, biomass sloughing increases. This can be accomplished by
altering the direction of flow through RBCs and submerged fixed film basins, or
by increasing or altering the aeration pattern (if any) in the basins. A second
means of inducing increased biomass sloughing is through chemical addition, but
this approach is potentially harmful to the biomass and should only be attempted
under the guidance of professionals skilled in the use of such chemicals.
4.1.5 Physical Modification
The most permanent type of industrial pollutant mitigation effort that can be
undertaken at the POTW itself comes in the form of physical addition to or
modification of the treatment system. Successful modification of treatment
plants for industrial waste effects mitigation have included the addition of new
plant facilities such as flow equalization and physical/chemical treatment steps,
the addition of facilities for adding chemicals (as previously discussed) to
existing treatment processes, and the modification of existing biological systems
(i.e. converting to oxygen activated sludge or replacing rock trickling filter
media with plastic media).
Flow Equalization. Adding flow equalization prior to biological treatment units
has the effect of dampening any slug or diurnal loads of noncompatible or
high-strength industrial contaminants entering a treatment plant. Pollutants
that intermittently enter a POTW in inhibitory concentrations can be diluted by
flow equalization to noninhibitory levels and thus, not adversely impact the
M?Jog-zcal system. Maiden Creek, Pennsylvania provides a dramatic example of
the effects of non-equalized industrial flows (see Figure A-4). In this particular
case, hydraulic shocks were accompanied by organic shocks that resulted in
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solids carryover, reduced BOD removal efficiency and sometimes total biological
process failure.
Instrumentation/Control. Some POTWs vise a variation of the flow equalization
principle with success, especially when toxic metal pollutants are involved. pH
and conductivity of the influent wastewater is measured and recorded con-
tinuously in the influent. When the pH drops or conductivity rises drastically,
possibly indicating an increased heavy metal level, the influent flow is diverted
to a holding basin until such time that the pH and conductivity in the influent
return to normal. At that, time, the diverted wastewater can be bled back to the
influent wastestream in a manner such that metal concentrations are diluted and
do not inhibit the biological system. This type of technique may become more
useful in the future as continuously recording specific ion electrodes are
developed for more pollutants.
An example of similar control steps is Chicago Heights, IL. Officials there were
alerted to a pesticide spill that entered the sewer system. Operators were able
to isolate the incoming spill to some parallel primary clarifiers, activated sludge
and aerobic digester tanks where the toxic materials were subsequently treated
chemically and biologically (Busch, 1986). Passaic Valley, New Jersey and
Newark, Ohio employ similar procedures when necessary (see Appendix A).
Special Treatment Operations. Other treatment steps that might be added
depend on the interfering industrial pollutants. The addition of
flotation/skimming tanks is beneficial for removing pollutants like oils, greases
or other water-immiscible compounds. Separate settling basins may be benefi-
cial in some cases for chemical treatment to precipitate metals or cause
coagulation of unsettleable solids.
Pure Oxygen Activated Sludge. Another type of treatment plant modification
that has experienced some mitigation success is the replacement of an existing
air activated sludge unit with oxygen activated sludge. Pure oxygen activated
sludge has been reported by U.S. EPA (1981c) to be a more biologically stable
process with improved sludge settleability over conventional air facilities when
responding to toxic or high-strength organic loadings. However, a disadvantage
with a covered oxygen system is that volatile organics can build up to potentially
explosive levels inside the covers. Baltimore, Maryland and Passaic Valley, New
Jersey have both experienced problems of this type.
Oxygen Transfer. Increasing the efficiency of oxygen transfer in aeration basins
will help mitigate the effects of high-strength conventional pollutants. Retro-
fitting existing coarse bubble or turbine aeration units with fine bubble units may
provide additional treatment capacity for a high-strength waste (see Newark,
Ohio and Maiden Creek, Pennsylvania in Appendix A). However, maintaining
oxygen levels above Z-3 mg/1 has not been shown to consistently result in a
better treatment of conventional or organic pollutants.
4.1.6 Summary
Table 4-3 summarizes the available measures that may be employed at a
treatment plant to mitigate interference effects.
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4.2 PRETREATMENT AND SOURCE CONTROL
Pretreatment and source control of interfering industrial pollutants is the most
direct and efficient way of mitigating the effects of industrial pollutants
because the cause of the interference never reaches the POTW. This reasoning
was the impetus for the General Pretreatment Regulations which specify the
guidelines under which municipalities must develop pretreatment programs. It is
not the intent of this guidance manual to discuss pretreatment guidelines,
complete program development or details of industrial treatment processes.
Rather, this discussion is intended to document elements important to bringing
about pollutant source control, whether as part of a municipal/industrial
cooperative agreement or a fully approved pretreatment program.
4.2.1 Local Limits
Setting local industrial discharge limits is one of the best and most direct ways
of mitigating any industrial interference that may exist at a POTW. Federal
Categorical Pretreatraent Standards must be applied by POTWs with federally-
approved pretreatment programs, but this does not guarantee interference
prevention because of the uniqueness of POTWs and the waste they treat. In
addition, nrmcategOTicai industries are not regulated by such federal standards.
Setting rational, technically-based local limits in a fair and equitable manner is a
sound approach to preventing interference. The General Pretreatment
Regulations (40 CFR Part 403.5(c)) require POTWs with federally-required
pretreatment programs and other POTWs which experience pass-through or
interference to establish local limits. Details on the development of local
discharge limits are contained in the "Guidance Manual for POTW Pretreatment
Program Development" (U.S. EPA, 1983). In addition, a computer
program/model for helping municipalities develop local limits has been
developed (U.S. EPA, 1985a) and is available from the EPA Office of Water
Enforcement and Permits.
4.2.2 Accidental Spill Prevention
It is in the best interests of any municipality to consider developing an
accidental spill prevention program (ASPP). The purpose of an ASPP is to
provide "...a set of procedures and a regulatory structure that will minimize the
chance that accidental spills of toxic materials will damage a municipality's
collection system or treatment plant" (U.S. EPA, 1986b). The principal
elements of an effective municipal ASPP are:
identification of potential sources and types of spill materials
adequate regulatory control
POTW review of industrial user spill prevention programs
complete emergency response procedures
documentation of the development strategy
Spill materials would include all sources and types identified for industrial
/yv?treatment, but would also include apparently insignificant users who have the
potential for spillage into floor drains connected to a POTW. Facilities such as
chemical warehouses, radiator shops, etc., which are supposedly "dry" or usually
recycle all harmful wastes, could have an accident that would impact a POTW.
49
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A POTW should require industrial users to develop their own in-house ASPP and
the program should be reviewed for thoroughness and effectiveness by the
POTW. Industrial user ASPPs, as well as the overall ASPP should include
complete emergency response procedures by all involved parties. These proce-
dures must be outlined in enough detail to be effective and all the appropriate
personnel must be adequately familiar with the necessary emergency steps.
Finally, the development of the ASPP must be well documented so that as time
passes and modifications become necessary, a written record of the program
development will be available for consultation. This record should prevent
needless rethinking of old ideas.
An active spill prevention program with a high degree of visibility can have a
positive impact on reducing unauthorized discharges of industrial wastes.
Figure 4-1 outlines the fundamental procedures in the development of an ASPP.
4.2.3 Pretreatment Facilities
There exists a wide variety of treatment processes applicable to industrial
pretreatment, depending on the wastestream pollutants, the volume of the
wastestream and the extent to which the waste must be treated. The application
of specific treatment streams is not addressed by this document. However,
many typical municipal treatment processes can be applied to some industrial
wastestreams. There are many other types of treatment processes, usually
physical/chemical, applicable to pretreatment applications.
In many cases where industries have been required to pretreat wastes, it has
been found that wastewater flow equalization, pH neutralization or conservation
and recycle/reuse have been all that are necessary to meet discharge limits and
eliminate interferences. Process modifications or wastestream recovery
processes (such as for metals) have in some cases ended up saving industries
money in addition to reducing pollutant loads. These aspects of pretreatment
should be emphasized in discussions with industries. The Horse Creek facility in
North Augusta, South Carolina, experienced significant operational improvement
from relatively small industrial operation changes (see Appendix A).
Modifications such as discharging sump water from the surface rather than the
drain and equalizing pumping schedules, so as to minimize hydraulic peaks were
typical of successful adjustments.
4.2.4 Regulation of Waste Haulers
POTWs that accept discharges of hauled waste should establish procedures to
control the wastes so as to ensure that they are compatible with the treatment
process. A waste hauler permit or "manifest" system is an effective method of
regulation. Use of such a system to document the origin, transportation, and
disposal of the waste, along with a source control program (permitting, sampling
and inspecting the generator) and predischarge sampling, will provide a high
degree of control over incoming wastes. Figure 4-2 presents an overview of the
procedures of a waste hauler permit system.
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POTWs may choose to restrict the discharge of hauled waste either to a
designated point in the collection system or to the plant itself. These
restrictions may be implemented through a permit or license. Larger POTWs
that can handle the slug load from a hauler, may grant access to the headworks.
In other cases, where storage or equalization capacity is available, hauled waste
may be discharged to equalization or holding tanks, where it can be charac-
terized prior to introduction to the system. Sioux City, Iowa has developed a
successful method to regulate the impact of waste hauler discharges (see
Appendix A). A large holding receptacle is utilized for all wastes and the
contents are metered to the treatment plant in controlled dosages, so as to
prevent any upsets from high strength waste.
If hauled waste discharges are restricted to a single site, the POTW can easily
inspect and sample the waste, verify tracking records, supervise the discharge of
the waste, and prohibit the discharge of wastes that would be incompatible with
the POTW. Such supervision will also discourage illegal discharges. Monitoring
of a collection system discharge point is more difficult than monitoring a
headworks discharge point. However, dilution of the waste is achieved when
discharged at a remote location in the collection system.
Waste generators may be regulated by permits specifying conditions such as self-
monitoring requirements, local limitations, categorical standards, specific prohi-
bitions, etc., which must be met before allowing discharge. Procedures to
control generators of hauled wastes should be similar to those employed for
generators of fixed discharges, since both are covered by the General Pretreat-
ment Regulations (40 CFR Part 403). The POTW may inspect the generator's
facility and sample the wastes for pollutants of concern to the POTW, as well as
determine if any other wastes have the potential for being mixed with the wastes
that are to be hauled. Based on inspection results, the POTW may sample for
those pollutants which should be limited before discharge is allowed.
If the POTW monitors the waste prior to discharge, one sample of the waste may
be analyzed for a single indicator parameter and a second sample preserved in
case any problems occur after introduction to the POTW. While this might
subject the POTW to unknown pollutants, it would save the cost of analyzing
each load extensively. In the case of manifest discrepancies, or where the
sample failed the indicator parameter test, or where an interference resulted,
more comprehensive testing could occur.
A waste hauler permitting and monitoring program should serve as a deterrent to
haulers against discharging illegal or harmful wastes. If deterrence alone is
unsuccessful, such a program could trigger enforcement action such as fines,
refusal of wastes, permit revocation, or assignment of liability for damages.
4.2.5 Planning for Future Sources
To prevent the likelihood of future interferences developing, POTW officials
must plan for future sources of industrial pollutants. Future pollutant loadings
should be considered from two sources: new industries, and new pollutant
streams of existing industries. Planning for future sources is particularly
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important as it relates to local limits development. Future pollutant sources and
quantities must be considered in setting local limits, so that a treatment facility
is able to handle increased pollutant loadings adequately.
4.3 LEGAL AND ENFORCEMENT REMEDIES
Interference is costly to POTWs in terms of worker safety, physical plant
integrity, effectiveness of operation, and liability for NPDES permit violations.
Interference is also a violation of a federal prohibition applicable directly to
industrial users. POTWs are required to establish local limits as necessary to
prevent interference and to take appropriate enforcement actions against
violators.
In order to prevent and quickly remedy interference, the POTW must be ready to
exercise its authority to take effective enforcement and legal actions. These
actions should be clearly defined and readily understood by all parties involved.
The range of enforcement mechanisms available to the POTW will depend on the
legal authorities given to it by the municipality, county, and state. Wastewater
treatment personnel who have not had extensive experience with enforcement
and legal proceedings in the past should consult with the POTW's attorney, city
solicitor, or comparable city official to determine what options are available.
POTWs which have federally-approved or state-approved pretreatment programs
should consult their program submission documents regarding legal authority and
enforcement procedures.
EPA has recently distributed a comprehensive guidance document for POTWs
titled Pretreatment Compliance Monitoring and Enforcement (PCME) Guidance
(EPA, 1986c). It provides detailed discussions on compliance monitoring,
establishing enforcement priorities, and conducting enforcement actions. The
PCME guidance should be examined by POTW personnel for the development or
review of their enforcement response procedures. POTWs are encouraged to
develop an enforcement response guide containing procedures which will define,
in a nonsubjective way, the type of enforcement response that can be expected
for a particular kind or level of violation.
Enforcement actions for POTW interference or industrial discharge noncom-
pliance are typically spelled out in the local sewer use ordinance, permits or
contracts with industrial users, or an approved pretreatment program. In
addition, the enforcement procedures can be described in the POTW's enforce-
ment response guide or their NPDES permit. It is important that the enforce-
ment options be strong enough to provide a real deterrent to the regulated
industries. This requires that adequate manpower and documentation exist to
pursue enforcement actions. Documentation will primarily consist of industrial
waste monitoring as discussed elsewhere in this manual. An in-depth evaluation
of all documentation concerning monitoring results, methods, and techniques, as
well as quality assurance procedures should be part of the preparation for
enforcement proceedings.
In interference situations in which there is imminent endangerment to human
health, the environment, or the POTW, it is important that the POTW have the
ability to immediately notify the discharger and bring about a halt to the
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discharge. POTWs with approved pretreatment programs are required to have
this authority by the General Pretreatment Regulations (40 CFR 403.8 (f)(vi)(B)).
In situations in which there is no threat of immediate harm, enforcement steps
usually begin with noncompliance warnings, meetings and other informal actions.
Should these measures prove inadequate, other more stringent measures should
be taken. These commonly include:
• penalties
• orders and compliance schedules
• litigation
• sewer disconnection and permit revocation
Bayshore Regional Sewerage Authority (Union Beach, New Jersey) and
METRO-Seattle, Washington are examples of POTWs which have shown aggres-
sive enforcement efforts {see Appendix A). These POTWs have not hesitated to
levy fines and take other enforcement actions after documenting the source of
interference problems.
Both formal and informal actions are important parts of an effective
enforcement program. Informal actions are likely to be more successful if the
POTW has developed a cooperative relationship with its industrial users.
Virginia's Hampton Roads Sanitation District provides a good example of the
advantages of developing and maintaining a good working and monitoring
relationship between an authority and the industrial user community. Once the
interfering source is located, the District technicians, along with a supervisor,
directly contact the industry to notify them of the problem and see to it that the
discharge ceases. The District approaches the source of any interference in a
cooperative manner, with ample documentation in hand. The source is normally
willing to rectify the problems and agreement on administrative and other
measures is reached informally, without the need to resort to legal remedies. If
a clean-up is warranted, the responsible industrial user contracts for the
necessary work to be done, with District personnel overseeing the operation until
completion. All costs involved with the investigation, clean-up and any other
District expenditures as a result of the upset are then billed to the industrial
source.
4.3.1 Penalties
After compliance warnings and effprts to encourage industrial pretreatment
have failed, the enforcement option most commonly initiated is the use of
penalties. The amount of a penalty is generally limited through state or
municipal laws. EPA's "Guidance Manual for POTW Pretreatment Program
Development" (October, 1983) recommendea that POTWs have the ability to
assess penalties of at least $300 per day of violation to act as a sufficient
deterrent. However, this limit may be inadequate for discharges which interfere
with the POTW. Appropriate action may involve seeking the assistance of the
state or EPA for obtaining penalties under state or federal law, which may be
substantially greater (up to $100,000 per day and 6 years in jail for a repeat
knowing criminal violation). Penalties may be used in conjunction with billing
procedures for minor violations which may be detected during inspections or
compliance review of self-monitoring data. Such penalties should appear as a
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separate item on a bill with the violation identified. The amount of the penalty
imposed will usually depend upon the nature and severity of the interference
caused or the quantity of the interfering pollutant.
Surcharges are not penalties, but rather recover the POTW's cost of treating
industrial wastewaters. Payment of surcharges is not a justification for an TU to
violate pretreatment standards or cause interference. POTWs should make it
clear to their industrial users, as part of the IU permit or contractual agreement,
that lUs may be subject to both surcharges for the additional treatment costs, as
well as substantial penalties for causing interference.
4.3.2 Orders and Compliance Schedules
In order to force an industrial user to install acceptable pretreatment equipment,
some POTWs may issue administrative orders to place an industrial user on an
enforceable compliance schedule to meet pretreatment standards. Additionally,
orders are sometimes used to require increased monitoring or installation of slug
notification systems.
The Hampton Roads Sanitation District, for example, may modify an industry's
discharge permit to reflect increased monitoring for a period of time to show
compliance. Also, a compliance schedule from the industry is required to show
what steps are taken to prevent recurrence. Depending on the severity of the
problem, the District may require the industry to permanently install some type
of alarm system and/or automatic shut-off.
4.3.3 Litigation
POTW-initiated litigation can be used as a further attempt to cause compliance
after earlier measures have failed to bring about the desired result. In many
cases, litigation is a way of obtaining an injunction against the discharger to
cease the discharge or to clean it up, or to obtain a sewer disconnection or the
payment of substantial penalties which go beyond routine fines. Litigation also
serves to bring media attention and public pressure to bear when pressure from a
sewer authority has failed. For example, the City of Canandaigua, New York
obtained an out-of-court settlement dictating a compliance schedule for a user
following the City's initiation of court action. The user was required to expand
its pretreatment facility and the City's POTW operation was then able to meet
its NPDES permit.
In some cases, litigation has been initiated to collect unpaid fines, which may
amount to sizeabVj sums. New Jersey's Bayshore Regional Sewerage Authority
found adverse publicity to have little effect on a major industrial employer, and
was forced to initiate legal action in an attempt to recover $1.25 million in back
surcharge payments and costs.
4.3.4 Sewer Disconnection or Permit Revocation
Sewer disconnection or permit revocation is used by many POTWs under serious
circumstances such as when there is imminent endangerment to public health,
the environment or the POTW, or when other methods to obtain compliance have
failed.
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A local ordinance can provide this authority by allowing the POTW to issue a
suspension order and by requiring the discharger to immediately halt discharging
upon notification. Furthermore, the ordinance can allow the POTW to sever the
sewer connection if the industry does not respond.
Frequently, unless there is an immediate threat to human health, an administra-
tive hearing of some type is held before discontinuing service. The industrial
user is invited to appear before a local hearing board, presented with the facts
demonstrating noncompliance, and asked to show cause why service should not be
discontinued. The board then decides whether to pursue disconnection.
Recently in New Jersey, the Hamilton Township Wastewater Treatment Plant
required an industrial user to install flow equalization equipment. However,
deterioration in effluent quality continued, leading to termination of sewer
service. In Pennsylvania, the Maiden Creek Wastewater Treatment Plant
discontinued service to a user when the discharge from the facility caused a
total process failure. Any future failure to comply with municipal requirements
for flow equalization and monitoring, BOD reduction, and sampling will subject
the user to another shut-off. The Bayshore, New Jersey Regional Sewerage
Authority's policy is to notify recalcitrant industries of a violation, with
subsequent discontinuation of service if noncompliance extends beyond 15 days.
At Hampton Roads in Virginia, if a problem represents an imminent hazard to
the public health, safety or welfare, or to the local environment or to any
portion of the sewerage system, the District may suspend a permit for a period
of up to 60 days. Failure to immediately cease discharge of all industrial
wastewater into the sewerage system may also result in termination of water
and/or wastewater service. If cooperation is not received from the user, then
the District may revoke the industrial user's permit.
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TABLE 4-1
BIOLOGICAL PROCESS CONTROL STEPS
Operating
Parameter
Control
Objective
Method of
Implementation
Result
Mean Cell Residence Time (MCRT) Increase
also known as Sludge Age
and Solids Retention
Time (SRT)
Mixed Liquor Suspended Increase
Solids (MLSS)
Food-to-Microorganism Decrease
Ratio (F./M)
Decrease solids
wasting rate
Increase solids
return rate
Increase solids
return rate
Quicker acclimation to
toxic pollutants
Better able to accommodate
fluctuating conventional
pollutant loads
Better biosorption and
acclimation
Improved toxic pollutant
biodegradation and acclimation
Source: U.S. EPA, 1986a
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TABLE 4-2
CHEMICAL ADDITIONS
Additive
Reason
for
Addition
Pollutant(s)
Causing
Problem
Point of
Result Addition
Chlorine
Reduce bulking
Various, particularly
textile and wood
products wastewater
Kills filamentous
organisms
Varies, but RAS &
aeration basin
effluent common
Phosphorus
Nitrogen
and Sulfur
Improve biological
treatment and
reduce bulking
sludge
High carbonaceous
strength waste
Corrects nutrient
deficient condition
Before aeration
basin
Lime or
Caustic
Polymers or
Coagulants
Powdered
Activated
Carbon
Reduce biological
inhibition
Improve
sedimentation
Reduce biological
inhibition
Heavy Metals
Various
Toxic organics
Raises pH causing
metals to precipitate
Removes toxics and
improves sedimentation
Adsorbs organic
pollutants
Before primary
clarifier
Before primary or
secondary clarifier
To aeration basin
Note: The generalizations in this table do not apply in all situations. The text should be consulted.
Source; James M. Montgomery, Consulting Engineers, Inc.
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TABLE 4-3
TREATMENT PLANT CONTROL MEASURES
Process
Biological
Process
Control
Biological
Augmentation
Chemical
Addition
Operations
Modification
Physical
Modification
Primary Clarification
Activated Sludge
Trickling Filters
Lagoons
Rotating Biological
Contactors (RBC)
Source: James M. Montgomery, Consulting Engineers, Inc.
-------
Evaluate
Pfretreatment
Program
o ASPP Requirements and Procedures
o Legal Authority Considerations
o Evaluate exiding community spill
prevention awl responds procedures;
I'OTW, fire department, health
rtrjMsrtsnent, etc.
o History of Spills and I'OTW Upseti
Develop ASPP Requirement*
Specific Jpill Control Equipment
to be Required
Administrative Procedures for iu
ASPP Submittal and Review
Procedures for spill detection,
nolif ica! ion, response,
investigation and follow-up
Enforcement mechanisms
Determine need for coordination
with other agencies
CUMiHcation of Industrial
Facilities
Surrey Industrial Community to
Determine Poienlially Regulated
Facilities
Notify Appropriate Facilities to
Collect Additional Information
Development Classification Scheme;
High, Moderate, Low Uisk
Review all Lidustria! Data to
Determine Each Facility's
Classification
Develop List of Affected Uaeri
ft Appropriately Categorize
Spill
ntioo tTogram
Formally notify facilities to
develop ASPPs
Review /approve IU ASPPs
Issue a control mechanism; issue
permit
Modify pretreatirieni inspection
program or develop an inspection
program to fulfil! needs of ASPP
Develop coordination agreements
with all agencies thai are
involved in program implementation
Sbill Response Prograin
Evaluate existing community
resources
identify other sources/agencies
to provide assistance and develop
coordination agreements
npvplop nrr^ssary rpsonrcf^ and
prtjo'ilurrs I o provide adr<|iiate
spill response capabilities
including staff training and
equipment
Determine Lead Agency for Spill
Response
Formalize and
Implement
ASPP Procedures
Program Modifications
o Evaluate Program Effectiveness
- Spill Prevention
- Spill Response
- Enforcement Mechanisms
- Administrative Procedures
o Modify ASPP program as necessary
FIGURE 4-1
FUNDAMENTAL PROCEDURES FOR POTW ACCIDENTAL SPILL PREVENTION PLAN {ASPP) DEVELOPMENT
(U.S. EPA, 19«6b)
59
-------
POTW notifies
hauler of
permit system
requirements
POTW random
sampling
of load
t
er
i
H
POTW compliance
action if permit
violated
provides
copy of
manifest
to POTW at
time of
discharge
FIGURE 4-2
PROCEDURES OF A WASTE HAULER PERMIT PROGRAM
(U.S. EPA, 1985a)
60
-------
REFERENCES
Busch, W.H. (1986) "Protecting Your Plant From Hazardous Waste." Operations
Forum, WPCF, April Issue. 11-15.
Geating, J. (1981) "Literature Study of the Biodegradability of Chemicals in
Water (Vols. 1 and 2)" U.S. EPA, Cincinnati, Ohio. Z41 pp.
Grubbs, R.B. (1986) "Biotechnology Proves Good Examples." Pollution
Engineering, June, 1986.
Russell, L.L., Cain, C.B. and Jenkins, D.I. (1983) "Impact of Priority Pollutants
on Publicly Owned Treatment Works Processes: A Literature Review." Proc.
37th Ind. Waste Conf. Ann Arbor Publishing, Ann Arbor, Michigan. 871-883.
Silva, S.J. (1981) "EPA Moving to Control Industrial Toxic Pollutants with New
NPDES Permits." Civil Engr. 51:76.
Slattery, G.H. (1986) "Patapsco Wastewater Treatment Plant Standard Operating
Procedure: Routine Operation of Wastewater Respirometer", Baltimore,
Maryland.
U.S. EPA (1977a) "Process Control Manual for Aerobic Biological Wastewater
Treatment Facilities." Prepared by Tsugita, R.A., De Coite, D.C.W. and Russell,
L.L. for U.S. EPA, Washington, DC.
U.S. EPA (1977b) "Federal Guidelines - State and Local Pretreatment Programs."
U.S. EPA, Municipal Construction Division MCD-43, EPA-430/9-76-017a,
Washington, D.C. 3 volumes.
U.S. EPA (1978) "Field Manual for Performance Evaluation and Troubleshooting
at Municipal Wastewater Treatment Facilities." EPA-430-9-78-001. Prepared
by Gulp, G.L. and Heim, N.F. for U.S. EPA, Washington, DC. 387 pp.
U.S. EPA (1979) "Biodegradation and Treatability of Specific Pollutants." EPA-
600/9-79-034. Prepared by Earth, E. F., and Bunch, R. L. for U.S. EPA,
Cincinnati, Ohio. 60 pp.
U.S. EPA (1981a) "304(g) Guidance Document: Revised Pretreatment Guidelines
(Vols. I and 13)." Internal Report. Prepared by JRB Associates for U.S. EPA,
Cincinnati, Ohio.
U.S. EPA (1981b) "Assessment of the Impacts of Industrial Discharges on Publicly
Owned Treatment Works." Report submitted to the Office of Water
Enforcement, U.S. EPA, Washington, D.C. by JRB Associates.
61
-------
U.S EPA (1981c) "Parallel Evaluation of Air and Oxygen-Activated Sludge."
EPA-600/2-81-155. Prepared by Austin, S., Yunt, F. and Wuerdeman, D., for
U.S. EPA, Cincinnati, Ohio, 43 pp.
U.S. EPA (1983) "Guidance Manual for POTW Pretreatment Program
Development." U.S. EPA, Office of Water Enforcement and Permits,
Washington, DC.
U.S. EPA (1984) "Improving POTW Performance Using the Composite Correction
Program Approach." U.S. EPA, Center for Environmental Research
EPA-625/6-84-008, Cincinnati, Ohio. 258 pp.
U.S. EPA (1985a) "PRELIM: The EPA Computer Program/Model for Developing
Local Limits - User's Guide." Prepared by SAIC/JRB Associates for U.S. EPA,
Office of Water Enforcement and Permits, Washington, DC.
U.S. EPA (1985b) "Pretreatment Implementation Review Task Force: Final
Report to the Administrator." U.S. EPA, Washington, DC. 75 pp.
U.S. EPA (1985c) "RCRA Information on Hazardous Wastes for Publicly Owned
Treatment Works." U.S. EPA, Office of Water Enforcement and Permits,
Washington, D.C.
U.S. EPA (1986a) "Interferences at Publicly Owned Treatment Works (POTWs)."
Submitted to U.S. EPA-WERL, Cincinnati, Ohio by James M. Montgomery,
Consulting Engineers, Inc.
U.S. EPA, Region X (1986b) "Guidance Manual for the Development of an
Accidental Spill Prevention Program." Prepared by Science Applications
International Corp. for U.S. EPA, Region X, Seattle, Washington.
U.S. EPA (1986c) "Pretreatment Compliance Monitoring and Enforcement
Guidance" U.S. EPA, Office of Water Enforcement and Permits, Washington, DC.
WPCF (1982) "Industrial Wastewater Control Program for Municipal Agencies."
MOP OM-4, WPCF, Washington, DC. 166 pp.
62
-------
APPENDIX A
CASE STUDIES
-------
TABI.K A 1
CASE STUDY SUMMARY TABLE
Treatment
Facility
Bark Kiver,
Balti-nore, Ml)
Patapsco,
Baltimore, MI)
Bayslx;re,
Union Beach, NJ
East Side,
Osw eg", NY
Hamilton Township,
Trenton, NJ
Horse Creek
North Augusta, SC
Contact
Person
Hob Moore
Plant Manager
C»01) Z88-6900
Herald Slattery
Pl.int Manager
(301) JS4^700
David Knowles
Manager
(201) 739-1095
John Mcfirath
Lab Supervisor
(315) 34^-3777
Thomas Andersen
Assistant Superintendent
(609) 890-3540
Stanley Wagher
Manager
(803) Z78-1911
Nature of
Interference
Episode
Kestrii -teil
Sludge disposal
Sewer syst fit
Explosion hazard
Inhibition
permit violations
Organic ov«>rload-
pennit violations
Suspended solids
overload - permit
violation
Upset conditions -
permit violations
Biomass inhibition
bulking sludge
Mow
Detected
I. ab analysis
Visual and sensory
observation
Respiromctry,
operating
difficulties
Lab analysis
Visual exaininat ion
Lab analysis
Lab analysis
Visual observation
Lab analysis
Method of
Causative Industrial
l'olliitant(s) Identification
Various tnel.tls
Various solvents Monitoring
Insect it ides, Uespirometry,
solvents, (-hemical
petroleum analysis
compounds
BOD, COD, SS Only major
industry
SS, BOD Only major
industry
BOD, SS, Volatile industrial
Organics community
Alkalinity, pll Industrial
SS monitoring
Mitigation
Step
Implemented pre-
treatinent program
I!e
-------
TABLE A-I
CASE STUDY SUMMARY TABLE (CONTINUED)
Treatment
Facility
Maxim <"r»»»rkt
Blandon, PA
MKTUO-West Point,
Seattle, WA
NPUSP River,
Raleigh, NC
Newark, OH
North Shore,
liurnpp, IL
Passaic Valley,
Newark, NJ
Sioux City, IA
Toileson, AZ
Contact
Person
Kdward < 'Uusman
Superintendent
(215) 926-4140
Douglas Milder-brand
Industrial Waste Supervisor
(206) 447-6743
Leon Holt
Pretreal ment Coordinator
(919) 779-2010
Roger Loom is
Assistant Superintenctanl
(614) 34S-0549
Frederic Winter
Director of Laboratory Services
(312) 623-6060
Frank D'Asrensio
Manager Industrial and Pollution
Control
(201) U4-ISOO
A.V. Flores
Project Manager
(712) 279-6169
Sterling Pillow
Manager
(60Z) 936-3381
Nature of
Interference
Episode
Treatment ups'-t dip-
to shock loading -
permit violations
N/A
Sludge cont.vuinat ion
Treatmpnt upsot d.ie
1 o shock load MHJS -
permit viol.it urns
Nit rif ic.at ion
inhibition, process
upsets
Treatment ups«-i -
pfrmit violation
Treatment upset due
to shock loadings -
slun
-------
BACK RIVER WASTEWATER TREATMENT PLANT
Baltimore, Maryland
The City of Baltimore owns and operates two wastewater treatment facilities,
Back River and Patapsco, with a combined flow rate of approximately
250 million gallons per day. The plants serve a combined population of nearly
1.7 million in an area which includes approximately 4,700 sources or potential
sources of nondomestic wastewater. In accordance with the requirements of the
General Pretreatment Regulations (40 CFR Part 403) established by the
U.S. EPA, the City developed an extensive industrial waste control program
requiring a significant commitment in terms of personnel, equipment, office
space, and supplies.
The Back River facility is currently undergoing a major renovation to replace the
30 acres of trickling filter rock media with complete-mix activated sludge, along
with significant alteration and expansion of most process units. The renovation
work is in preparation for new NPDES permit limits of 10/10 (BOD and TSS) and
2 mg/1 (NH3), which will require extensive modification of the system for
nitrification and multi-media filtration. Industrial flows to Back River total
approximately Z7 mgd, resulting in metals and solvents in the discharge.
The primary source of metals in the system is from the 12 metal plating
operations identified by the industrial waste survey. If too high, the metals
content in the wastewater restricts the ultimate disposal options for the digested
and dewatered sludge. When local limits were calculated based on unrestricted
distribution of the sludge, the limits were occasionally one-fourth of the
electroplating categorical standards. A compost facility now under construction
is expected to process 150 wet tons of the 450 tons produced each day, beginning
in March 1987.
The benefits of pretreatment for metals removal have been demonstrated at
Back River. An incinerator had been discharging 2 tons of fly ash per hour into
the collection system, which was high in metal content and was responsible for
90 percent of the cadmium in the POTW influent. Other wastewater containing
metals were from steel and automobile manufacturing. In each case, industrial
user pretreatment facilities have come on-line during the past year, with a
measureable drop in influent and sludge concentrations. A summary of the
improved metal content of the sludge from 1984 to 1986 is provided on
Table A-2. Based on the current metal content, the composted sludge will be
acceptable for agricultural use.
The second major area of concern at the Back River plant sterns from the large,
baich discharges of solvents, petroleum hydrocarbons and other toxic organics.
In 1985, a 2:00 am discharge of ethyl benzene, xylene and toluene resulted in the
evacuation of the largest pump station and other buildings in town. The problem
was traced to a paint and chemicals manufacturer, which has since improved its
in-house solvent recovery system. A similar evacuation resulted from a
4,000 gallon discharge of xylene by a waste hauler, which was traced to a
A-3
-------
specific location in the collection system. Tetrachloroethylene has been
discovered and traced to dry cleaning operations. While such discharges have not
usually resulted in interference with the plant's ability to meet its NPDES permit
limits, the health and safety issues and potential for explosion are of serious
concern to the City.
TABLE A-Z
AVERAGE METAL CONTENT OF
BACK RIVER SLUDGE
(mg/kg dry weight basis)
Metal Allowable1 1984 1986 % Reduction
Cr (total)
Cu
Pb
Ni
Zn
Cd
Hg
NA
1960
730
575
5,130
48
12
1,491
1,001
372
266
2,747
26
5
273
549
388
67
1,522
17
3
82
45
-4
75
45
35
40
From Compost Contract Schedule 2, City of Baltimore, MD
An interesting aspect of Baltimore's program for preventing interference and
sewer system hazards is the computer coding of the sewer collection system. By
knowing the constituents of each industry's discharge, the flow rate and their
location in the coded sewer system, a contaminant discovered at either Back
River or Patapsco can theoretically be traced back to its potential source or
sources. While such a backtracking program is of limited use for isolated
discharges, it could prove beneficial in locating chronic dischargers of specific
compounds.
In order to further protect the sewer system, a City Ordinance requires that the
atmosphere in a manhole receiving an industrial discharge must not exceed 10%
of the LEL (lower explosive limit) for any fuel. This regulation is in force by
manual monitoring of the sewer manhole and has been successful in curbing
intentional dumps or disposal of fuels and flammable solids.
A-4
-------
BACK RIVER WASTEWATER TREATMENT PLANT
BALTIMORE, MARYLAND
Design Flow:
Secondary Treatment:
110 mgd
Trickling Filter* and Activated Sludge
INFLUENT WASTEWATER
Ave. Flow, mgd
% Indus trill
BODj, rag/1
SS, tug/1
Typical (Dpiet)
180 1270)
15
no
!90
Industry
Metal Plating M Z)
Auto Mfr.
Paint tnd Chemical
Incinerator
Waste Haulers
SIGNIFICANT INDUSTRIES
Flovrate
(mgd)
0.18
1.5
N/A
NY A
N/A
Problem
Metals
Cr, Cu, Ni, Zn
Pollutaata
Ethyl benzene, toluene, xylene
Cd, Hg
Solvents, petroleum
hydrocarbons
PLANT LOADING
Primary CUri fieri
Overflow Rate, ga!/sf/day
Detention Time, hours
Effluer.; BOD5, mg/1
Effluent SS, mg/1
Secondary Clarifiers (A.S./T.F>
Overflow Rate, gal.'sf'diy
Detention Time, hours
SV1, ml/gm
Typical (Upset)
'30 11,170)
3.6
180
100
Typical (Upset)
750/950
:.5/M
95
Aeration
Ave. Flow, mgd
F/M, Lbs BOD5/:bs MLSS/day
MCRT, days
MLSS. mj/1
Detention Time, hours
Return Flow, To
D.O. Level, mg/1
Trickling Filter*
Ave. Flow, ragd
Hydraulic Loadings, ga/sf/i
Organic Loading, Ibs BOD/1000 cf/d
Return F!ow, %
Typical (Up*et)
60
0.4
6.1
:,ooo
3.5
30-40
Typical (Upset)
150 (2001
UO '13d
iO
3
30^;, rr.g/1
SS, mg/1
PLANT PERFORMANCE
Permit Limit
-15
45
Typical (Upset)
40 (50)
10 1531
«A«V WASTEWATER
BETHLEHEM STEEL
COOLING WATER
FINAL EFFLUENT
A-5
-------
PATAPSCO WASTEWATER TREATMENT PLANT
Baltimore, Maryland
A 1981 EPA-sponsored project on biomonitoring of direct discharges rated the
Patapsco plant as having the most toxic effluent of those surveyed. Ironically,
the second most toxic discharge came from an agricultural chemicals manufac-
turer who, in 1983, ceased direct discharging and now sends their pretreated
wastewater to Patapsco. The high level of toxicity has prompted the collection
of much bioassay, acute toxicity and respirometer data over the past four years
in order to evaluate the potential for both toxicity pass-through and toxic
inhibition of the plant biomass. Despite the presence of inhibitory levels of
pollutants in the influent, the plant currently meets its discharge limits for BOD
and SS, indicating the ability of activated sludge to acclimate to consistent
levels of many inhibitory compounds. It has, however, been necessary to operate
at a reduced organic loading in order to offset the effects of the inhibition. This
has reduced the wastewater treatment capacity of the plant.
The City is evaluating several measures to reduce this inhibition and thus
prevent any possibility of interference. They have begun daily routine operation
of a respirometer for measuring the inhibitory characteristics of the plant
influent. They are also evaluating the use of respirometry as a tool for assessing
the impacts of several industrial effluents on the plant.
Another concern to the City is the pass-through of toxicity. Acute influent and
effluent toxicity data using a Beckman Microtox unit have been collected since
November 1980. Some of the results of these analyses are shown on Figure A-l.
The data are on an inverse scale, with 0% indicating complete toxicity and
approximately 45 percent corresponding to no toxic effect.
Figure A-l illustrates the highly toxic nature of the plant influent and effluent
until September 1982, at which time the secondary treatment system went on-
line. The acclimation of the activated sludge improved the monthly average
effluent toxicity from 5 percent to 40 percent by December, where it remained
until secondary shutdown in February 1983. The average effluent toxicity again
increased until the secondaries returned on June 15, providing clear evidence of
the detoxification capability of acclimated activated sludge. Even though
overall effluent toxicity has been reduced, individual daily tests continue to show
substantial day-to-day variability, with significant effluent toxicity occurring in
more than one-third of the tests. Therefore, the City is continuing to study ways
to reduce this toxicity pass-through. In fact, the City of Baltimore is currently
performing a toxicity reduction evaluation (TRE) in conjunction with the U.S.
EPA.
As a means of improving both the inhibition and toxicity pass-through situations,
the State of Maryland included the following in a consent order issued to the
City in 1984:
• install on-line toxicity monitoring of the plant influent
• develop a toxics emergency response plan
• enlarge the scope of the City sewer ordinance to include specifics on
toxicity and flammability for industrial effluents.
A-6
-------
EH
M
u
i-H
X
o
E-
CO
u
iiliUliliiai!ilHllliH\ltiii
!«.-»(_ j Oil I IT
FIGURE A-l
MONTHLY ACUTE TOXICITY
(Courtesy G.H. Slattery, City of Baltimore)
In spite of high influent toxicity, the plant is not currently experiencing
interference with its ability to meet its NPDES permit limits. With a mean cell
residence time varying between 10 and 15 days, the plant produces reasonably
stable operation and good plant performance on removals of conventional
pollutants. Although compliance with the NPDES permit has been achieved for
BOD and SS at Patapsco, the plant flow is well below the 70 mgd design
capacity. Toxic inhibition of the activated sludge bacteria is still present
despite the improvement since 1983. Evidence of this inhibition is provided by
the plant actual operating F/M of 0.3, which is significantly less than the design
value of 0.5, and also was verified by respirometry tests on the plant influent.
The attached data sheet indicates that Patapsco's current noncompliance has
resulted from discharging excess phosphorus and an effluent pH below 6.5. The
phosphorus problem is being dealt with by installing anaerobic/oxic (A/O)
technology in the oxygenation basins as a means of biological phosphorus
removal. The low pH is inherent in oxygen activated sludge systems, typically
producing an effluent in excess of 250 mg/1 of CO^ and a pH of 6.2. The problem
can be corrected with either chemical adjustment or post-aeration of the
wastewater.
A-7
-------
PATAPSCO WASTEWATER TREATMENT PLANT
BALTIMORE, MARYLAND
Design Flow:
Secondary Treatment:
70 mgd
ActIT»ted Sludge (Pure Oxygen)
INFLUENT WASTEWATER SIGNIFICANT INDUSTrUES
Ave. Flow, ragil
™t Industrial
BOD";, raz/1
SS, mg/l
TOX, %
Flovrate
Typical (TJpMt) Industry Imgd) Problem PoUutanti
•i2 Chemicals 1.0 Insecticides, Volatile*, phenols, metaU
30
165 13ZO) Metal Finishing C.13 pH, solvent^, raetali
325 (470)
15
Primary Clvillerm
Overflow Rate, gal'sf'day
Detention Time, hours
Effluent BOD;, mg/l
Effluent SS, rag/1
Secondary CUrifiers
Overflow Rate, gal, sf day
Detention Time, hours
PLANT LOADING
Typical I Upset) Aeration Eaiuu
1,150
1.5
PO
30
Tfpica! (Upsst)
-ISO
F/M, Ibs 3OD5/lbs MLSS/day
MCRT, clays
MLSS, mg/l
Detention Time, hours
Reijrn Flow, "
D.O. Level, mg,'.
lypicai (Upseti
0.3
1C-15
5,COO
3C
2-4
55. mg.M
Total-P, mg. !
PLANT PERFORMANCE
Permit Limit
•3.5-S.S
Typical (Upset)
: i 40'
:; 40'
RAW WASTEWATER
RA3
FINAL EFFLUENT
SCREENS
PRIMARY
CLARIFIERS
<3)
•
1
I
i
OXYQENATK3N
BASINS
(4)
•
AIR
FLOTATION
THICKENERS
(4)
SLUDGE
LENDING
TANKS
(2)
ASH TO
LAQOON
A-5
-------
BAYSHORE REGIONAL SEWERAGE AUTHORITY
Union Beach, New Jersey
The Bayshore Regional Sewerage Authority (BRSA) operates an activated sludge
treatment facility whose performance is largely dictated by a single industrial
waste discharger. Three manufacturers of flavors and fragrances (one of whom
is a perfume retailer) represent the total industrial wastewater flow of
325,000 gpd, or less than 5 percent of the POTW total. All three industries
discharge high concentrations of conventional pollutants and routinely violate
the maximum allowable monthly concentration limits for BOD (500), COD (1500)
and TSS (500) as specified in their industrial waste permits. Two of the three
manufacturers contribute less than 0.5 percent of the POTW flow, hence their
impact is minimal. However, one building of the largest industry produces in
excess of 200,000 gpd of wastewater with the following characteristics (in mg/1):
1984 October 1985
Monthly Monthly Daily Daily
Parameter Ave. High Lew Ave. High Low
BOD 1004 2054 245 2624 5250 522
COD 3Z38 4998 1440 7084 11380 2520
TSS 776 1835 94 1113 1698 672
The large variation in wastewater quality indicates that a two-stage primary
pretreatment system located at the industry is not sufficient to meet the
fluctuating demands of their process wastes.
The potential impact of such an industrial discharge is evident when analyzing
Figure A-2. The bar graph represents the percentage of total BOD being
contributed by the industry on a daily basis. The upper plot on the line graph
corresponds to the mass BOD loading, with the industry's contribution plotted
beneath. This graph clearly demonstrates that the effluent from this single
industry has increased the BRSA plant loading above the design limit of
15,000 pounds of BOD per day. This has interfered with the plant's ability to
meet its permit limit for BOD.
The BRSA has been particularly aggressive in their dealings with the industry in
question. It has taken a two-pronged approach:
• notification of violation with a subsequent discontinuation of service
if noncompliance persists after 15 days, and
• legal action to recover $1.25 million in back surcharge payments and
costs.
A-9
-------
•00 COMf AftMOW
WMMT** »OO ft! % Of TOTAL K>D
•:
Figure A-2
Impact of Industrial Waste Discharge on POTW Loadings
October 1985
In addition to the BRSA actions, the County Prosecutor's office made a surprise
visit to the industry in question, in which records were confiscated and samples
collected for analysis. The result was a $5 million fine levied by the State of
New Jersey in June of 1986, coupled with new NJPDES permit POTW limits. As
a direct consequence of the state and local acions, the industry's wastewater
BOD and SS have each been consistently below 100 mg/1 since July, 1986. To
date, $300,000 of the back payments have been received by the BRSA, with some
litigation still pending.
A-10
-------
BAYSHORE REGIONAL SEWERAGE ADTHORTTY
Union Beach, New Jer»ey
D«iign Flow:
Secondary Treatment:
8.0
Activated Sludge
(Modified Contact Stabilization)
Location: Eastern shore
Population Served: 80,000
INFLUENT WASTEWATER
Typical (Op*et)
Ave. Flow, ragd
% Industrial
BOD;, mg/l
55, mg/1
6.6
5
220 (380)
250 UOO)
Industry
Flavorl it Fragraj-.ces
(3 industries)
SIGNIFICANT INDUSTRIES
Flo write
(1000 gpd)
325
Problem Pollutants
BOD, TSS, COD
PLANT LOADING
Primary CUrifien
Overflow Rate, g«!/sf/day
Detention Time, hours
Effluent BODs, mg/1
Effluent SS, tngA
Secondary CUrifien
Overflow Rate, gal/«f/day
Detention Time, hours
SVT, ml/gm
Typical (Dpset)
825
1.75
150 (250)
100 (ZOO)
Typical (Upset)
540
3.35
IZS (500)
Aeration Basins
F/M, Ibs BODj/lbs MLSS/day
MCRT, days
MLSS, rag/1
Return Flow, "a
Detention Time, hours
Contact
Reieration
Typical (Dpset)
0.65 (1.25)
3-10
ZOOO-2500
25
3
12
BOD5, mg/1
SS, rag/1
D.O. rog/1
PLANT PERFORMANCE
Permit Limit
30
30
Typical (Upset)
35 '4?0)
2- .ir.
RAW
rVASTEWATEH
EFFLUENT
ASH TO
SLUDGE LAGOON
INCINERATOft
A-11
-------
EAST SIDE SEWAGE TREATMENT PLANT
Oswego, New York
The City of Oswego, East Side Treatment Plant has experienced significant non-
compliance problems associated with the loss of solids from their secondary
clarifiers. Half of the plant's hydraulic flow is from a paper mill which is the
only major industry in the city. From 1981 to 1983, the noncompliance problems
at the plant were attributed to severe hydraulic and organic load peaks from the
paper mill as well as operational difficulties such as frequent breakdowns of the
return sludge pump drives. It is not known whether filamentous growth in the
sludge occurred at that time. In 1983 the paper mill began reducing the
hydraulic and organic peaks to the plant. Solids losses from the secondary
clarifier still remained a problem. During 1984, the plant frequently exceeded
their NPDES discharge suspended solids by five times the limit and the BOD by
three times the limit. During that period, the plant still occasionally received
hydraulic peaks from the paper mill which were twice the average rate for two
to three hour periods, but a substantial cause of the problem was identified as
poor sludge settleability due to filamentous growth. The frequent washout of
biosolids from the secondary clarifiers resulted in a low mean cell residence
time and the generation of a young sludge that did not settle well. In the spring
of 1985, the belt drives on the return sludge pumps which had frequently been
out of service were replaced with electronic variable speed drives. This
improvement allowed the plant operators to maintain better control of the solids
inventory in the aeration tanks. Plant performance was still poor, however,
because of sludge bulking.
Several measures have been taken at the plant in an attempt to alleviate the
sludge bulking problem. The measures that were taken include:
• switching from plug flow feed to a step feed in the aeration tanks in
order to achieve better dissolved oxygen distribution;
• increasing the sludge return rate and mean cell residence time to
improve settleability; and
• chlorination of the return sludge for the destruction of filamentous
growth in the sludge.
The step feed operation has resulted in better dissolved oxygen distribution but
did not significantly improve sludge settleability. The second two mitigation
efforts were ongoing at the time of writing. A chlorination dosage of
6 Ib C12/1000 Ib solids had been applied to the return sludge. Microscopic
examination of the sludge indicated that the filaments had shrunk and the SVI
level had dropped to the range of 60-80. The plant operators intend to chlorinate
whenever the SVI increases to 150. It has not been determined if these
mitigation measures can result in plant performance that will consistently meet
the permit discharge limits.
The paper mill periodically discharges slugs of waste containing high suspended
solids to the treatment plant. At these times, the sludge in the primary tanks
A-12
-------
takes on a gelatinous quality which makes sludge removal difficult. High
periodic input of clay filler materials from the paper mill has resulted in poor
sludge incineration with associated high fuel usage.
The City of Oswego is presently preparing an industrial discharge permit for the
paper mill. The permit will restrict the monthly and daily average BOD and
suspended solids levels in the influent from the paper mill as well as restrict the
daily maximum hydraulic peak allowed. Under the permit provisions the paper
mill will be required to submit listings of the chemicals used in their processes.
The paper mill is presently investigating the possible relationship of the
chemicals used in their manufacturing processes to the occurrence of
filamentous growth in the activated sludge process.
A-13
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EAST SIDE SEWAGE TREATMENT PIJUCT
OSWEGO, NEW YORK
Design Flow: 3 mfd
Secondary Treatment: Ping or Step Feed
Activated Sludge
INFLUENT WASTEWATER
Typical (TJpMt)
Ave. Flow, mgd 2.5
V, Industrial SO
Municipal Papa Mill
BODs, mg/1 100 300
SS, mg/1 120 450 (1000)
Location: Northern
Population Served: 10,000
SIGNIFICANT INDUSTRIES
New York
Flowrate
Industry (1000 gpd) Problem Pollutant*
Piper Mill 1,200
SS, BOD
Primary Clarifien
Ortrflow Rate, gal/if/iiy
Detention Time, hours
Effluent BOD$, tng/1
Effluent SS, mg/1
PLANT LOADING
Typical (Opaet) Aeration Baiin*
Municipal
70
40
600
2
Paper Mill
120
100
F/M, Ibi BOD5/lb« MLSS/day
MCRT, days
MLSS, mg/1
Detention Time, hours
Return Flow, %
D.O. Level, mg/1
Typical (Upaet)
O.Z
7 ;3i
2,000 1300)
1
i5 - 45
2-4
Secondary Clarifien
Overflow Rate, gil/if/diy
Detention Time, hours
SVT, ml/gm
Typical (Up»el)
soo
2
ICC (10001
PLANT PERFORMANCE
Permit Limit
Remainder of
Summer Year
Typical (Up«eO
BCD;, njg/1 30 45 20 UiOl
SS, oeg/1 30 70 25 (3001
«AW OOMEITIC K«W »«t« MH.I
WA.TIWATH WA.TEWATEH r(MAl
Y I CFFlUtMT
j icMlJ" t
! I I _
1 1 CHlOMMt
1 OMIT CHAIKEIt
CMAMCIIrl
1 L_
1 ,1 r*nu»i 1 1 I 1 j T t
^ ^JCIAHIFIMHIJ -] A...T«« MCOMO..Y
j U lAamt — *. CLAHtfitm _
( r\ ••'"*•» LJ F '*'
^> pL«BiF«»«(if j 1 — r1
i _J 1 — "**_ -J
L..___-_I__^A( _ J
1^^
X^'"^/ f~^-\ *=~~-~-^ " LAKOfK.1
t J HULTIPIE HEADTH
J
A-14
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HAMILTON TOWNSHIP WASTEWATER TREATMENT PLANT
Trenton, New Jersey
The Hamilton Township Wastewater Treatment Plant (HTWTP) is an unusual
facility in that plant upgrades over the past 30 years have been constructed as
parallel flow processes rather than as replacements for older, outdated techno-
logy. Although this results in a complicated plant schematic (see below), parallel
flow paths do provide operational flexibility and an opportunity to study the
impact of a combined industrial/domestic wastewater on different fixed-film
biological treatment processes. The HTWTP has had a difficult time meeting its
permit limit for BOD over the past few years, and is currently under a Consent
Order and Agreement and Compliance Schedule from the State Department of
Environmental Protection.
Despite being at just over 50 percent of the plant's hydraulic capacity, Hamilton
Township has experienced organic overloads, resulting in at least partial failure
of 15 of the 48 RBC units. With the advent of an Industrial Waste Monitoring
Program as part of a Sewers and Sewage Disposal Ordinance, the reasons for
such overloading became apparent. Although the industrial waste program is
still in its infancy, observations and analytical data have identified a pharma-
ceuticals manufacturer as a significant and potentially harmful discharger to the
POTW.
Dating back to the summer of 1984, high concentrations of volatile organics
were being discharged to the POTW on a once or twice-per-week basis. A
monitoring program at the HTWTP uncovered an increase in influent BOD from
150 to 350-500 mg/1 and high atmospheric levels of organic constituents with
this discharge pattern. The specific industry was identified when a high influent
pH reading led Hamilton Township personnel to the Pharmaceuticals manu-
facturer in March, 1985. Sampling conducted at that time detected significant
levels of ethyl benzene, toluene and xylene in the industry's effluent. These
findings precipitated an extensive testing program by the Township, with an
independent engineering study conducted by the industry. The results indicated a
correlation between the pharmaceutical discharges and high influent soluble BOD
at the POTW. Analyses conducted on the industry's flow streams resulted in the
following calculated average effluent concentrations:
Parameter Concentration (mg/1)
Arsenic 2.6
Phenols 25.7
Total Toxic Volatile Organics (TTVO) 1.3
BOD 21,800
TSS 557
TDS 65,800
Based on an average flow of 15,000 gpd, these wastewater characteristics should
not be harmful to an 8.5 mgd facility if discharged on a steady basis. It is the
intermittent discharge of this wastewater which has contributed to the over-
loading of the biological population of the POTW.
A-15
-------
During a three week shutdown of the industry in July of 1985, the HTWTP
recovered to the point of meeting their permit limits. Consequently, the
Township only permitted the industry access to the sewer system after the
installation of metering pumps to equalize flows. This requirement initially
improved POTW performance during the fall of 1985, biit a gradual deterioration
in effluent quality (indicating possible toxicity effects) lead the Township to
terminate service to the industry in late-November.
While the most recent action is being challenged, the industry is constructing an
anaerobic pretreatment facility on site to reduce its loading to the POTW.
A number of operations and personnel changes have been instituted at the
HTWTP to help mitigate the impact of the industrial discharges. These changes
include:
• installation of aeration equipment in the influent channels to the
RBCs to increase the first stage DO to 2-3 mg/1;
• extensive use of sludge depth measurement and visual monitoring to
augment reliance on control room instrumentation;
• performance of bioassay testing by an independent contractor to
assess toxicity effects;
• purchase of a toxicity tester to be used in calculation of local limits;
and
• hiring of four more people plus the purchase of a vehicle for an
extensive industrial sampling program.
A-16
-------
HAMILTON TOWNSHIP WASTEWATER TREATMENT PLANT
Teuton, New Jeney
Design Flow;
Secondly Treatment:
16 mgd
Trickling Filter and RBC
Location:
Population Served:
Central Western Borde
37,000
INFLUENT WASTBWATER
SlfiNOTCANT INDUSTRIES
Ave. Flo-*, rngd
"a Industrial
BOH5, mg/l
SS, mg/l
Typical (Op«etl
3.5
ID lejti
340 '500'
L6C :400!
laduatry
Pharraaceutical
^lectroplaters ''21
Flowrmte
(1000 gpd)
15
160
Problem Pollutants
SCO, phenol, ethyl beniene, toluene, xyier.e
Cd, Cr, Zn, Mi
Primary Clarifieri
Overflow Rate, g
Detention TiTEe,
PLANT LOADING
Typical (Op»et) Trickling FUtert
S30, IbO. iZO
v.s, A.?,, ;.ti
TyptcaJ (Dp»et)
Pli-.t 71ovc 'rngd! 1.5, 1.0
Hydraulic Loading, jal'sf/iay 100, ?-10
Organic '.oading,':'is 3OD/'1,000 cf/day 15, Id I30>
Return Flow, % 20,100
Secondary Clarifiers
Overflow Rate, jal'jf-'dav
Detention Time, hours
Typical (OpMt>
ilO, Ibd, :65
l.a, 4.S, 6.1
RBC«
Plant Flow (mgdi
First Stage Organic
Lna-iing, Ibj BOD/1.000 sf.'day
- Total
- Soluble
Typical (Dpaet)
;.i rio.a;
3.5 '6.71
PLANT PERFORMANCE
Permit Limit
303;. ras :
ss. -i :
NH3. Tg '. Zffective i/86:
30
Typical (Upset)
45 1100
:o .5-0;
:: 3-r
RAW
WA8TEWATEA
A-17
-------
HORSE CREEK POLLUTION CONTROL FACILITY
North Augusta, South Carolina
The Horse Creek Pollution Control Facility (HCPCF) is a regional plant,
operated by the Aiken County Public Service Authority (ACPSA), treating a
predominantly industrial wastewater. Ninety five percent of the industrial
wasteload is contributed by several large textile mills and is characterized by
high COD, BOD, alkalinity and pH. Combined domestic/industrial influent
wastewater pH and alkalinity fluctuations caused inhibition of the biomass,
poorly settling sludge and effluent suspended solids permit violations. Since
implementing a pretreatment program and issuing industrial wastewater
discharge permits, the treatability of the industrial waste has improved, the
result being that HCPCF has been free of NPDES permit violations for over
eight months.
Local textile processes include grading operations, finishing processes utilizing
dyes, and specialized textile chemical manufacturing. The textile wastewater is
highly caustic with alkalinity as high as Z400 mg/1, and pH exceeding 1Z.5. Prior
to pretreatment the combined industrial/domestic influent to the HCPCF had
the following characteristics:
pH >11
BOD 360 mg/1
COD 910 mg/1
Alkalinity 1100 mg/l
TSS 210 mg/1
Other distinguishing characteristics of the influent wastewater included the
light, non flocculant nature of the suspended solids and a dark blue/black color,
typical of textile wastewater from washing and dying operations.
Prior to the summer of 1985, the textile industries employed a limited type of
pretreatment and flow equalization. This limited pretreatment and flow
equalization resulted in plant influent pH fluctuations of 2 to 2.5 units and
alkalinity fluctuations of up to 600 mg/1 in a given day. These fluctuations
caused some inhibition of the biomass, but because the hydraulic detention time
in the aeration basins was in excess of 3.5 days, effluent BOD was within the
permit limit of 33 mg/1. These pH and alkalinity fluctuations had their most
detrimental effect on biomass settling characteristics and solids carryover in the
secondary clarifier often resulted, lasting for 24-36 hours. During these
episodes, filamentous organisms were occasionally observed in the biomass. The
solids carryover problem worsened in the winter months when wastewater
temperatures were lower, but chlorination of the return activated sludge, the
influent to the secondary clarifier and the contents of the aeration basin was
somewhat successful at improving settleability. Despite this, the HCPCF still
experienced interference with its ability to meet suspended solids limits in 15 of
the 19 months prior to September, 1985.
The State of South Carolina mandated that the ACPSA implement and enforce a
pretreatment program in the spring of 1984. The ACPSA responded by
A-18
-------
developing such a program and issuing draft industrial wastewater discharge
permits. Final State approval came in May, 1985. As presently written, the
industrial wastewater discharge permits are not restrictive, allowing BOD, COD
and alkalinity levels as high as 600 mg/1, 1300 mg/1 and 1500 mg/1, respectively.
However, the permits have caused the textile industries to make small, but
meaningful alterations to their wastewater discharge practices, resulting in
average plant influent pH levels dropping from 11-12 to 10 and alkalinity from
1100 mg/1 to 700 rng/1. More importantly, maximum daily influent pH
fluctuations have been, reduced to 0.5 units or less. Figure A-3 shows the
magnitude of pH fluctuations both before and after the implementation of
pretreatment. Simple modifications at textile facilities to process operations
and waste pumping schedules were typical of the changes that were necessary to
realize the described results. Because of the more stable wastewater discharge,
the HCPCF has realized more consistent plant operation and has not violated its
NPDES permit in over eight months.
Some of the textile dischargers do not currently meet the pH and alkalinity
limits of their industrial wastewater discharge permits and are under a
compliance schedule to do so. The facilities are installing pretreatment works
for caustic recovery that should significantly lower pH and alkalinity levels. The
HCPCF is also presently studying the addition of floating mixing units -to
augment the turbine surface aerators in the aeration basins. To date, evidence
indicates that a more consistent secondary clarifier solids feed is achieved which
improves the quality of the secondary effluent.
FIGURE A-3
HORSE CREEK POLLUTION CONTROL FACILITY INFLUENT pH
A-19
-------
HORSE CREKK POLLUTION CONTROL FACUITY
Alke* County, South Carolina
Deiign Flow:
Secondary Treatment:
ZOmgd
Extended Aeration
Activated Sludge
Location:
Population Served:
Veat-cc
70,000
itraj South Carolina
INFLUENT WASTEWATER
Typical (Upaetl
SIGNIFICANT INDUSTRIES
Are. Flow, mgd
% Industrial
BOD;, mg/1
SS, mg/1
COD, mg/l
Alkalinity, mg/1
pH
10.4
80
360
210
910
1100 (1600)
10-11 (U.51
Jnduatry
Textile
Teitile chemicals
Flowrate
(lOOOgpd)
8,400
300
Problem Pollutant*
COD, Alkalinity, pH
COD, pH
PLANT LOADING
Primary CUrifiera
Overflow Rate, gal/if/day
Detention Time, hours
Secondary Clarifien
Overflow Rate, gal.'sf'day
Detention Time, hours
Typic
100.
4.4
Typical (Upset)
195
9.;
Aeration
-F/Mj-rbi-BODj/Ibi MLSS/day
MCRT, days
MLSS, mg/1
Detention Time, hours
Return Flow, r
-------
MAIDEN CREEK WASTEWATER TREATMENT PLANT
Blandon, Pennsylvania
The Maiden Creek Wastewater Treatment Plant (MCWTP) went on-line in
December, 1981 as a secondary treatment facility designed to remove both
carbonaceous and nitrogenous BOD. The plant uses a patented aerated sub-
merged fixed film biological treatment system, where flat asbestos plates
hanging vertically in the settled wastewater provide a growth surface for the
bacteria. Each of three contact basins contains 320 plates with 200 sq. ft. of
surface area. Oxygen is provided by fine bubble aeration through ceramic
diffusers.
During the first six months of operation following an initial acclimation period,
the MCWTP experienced gradual flow increases from 0.1 to 0.15 mgd while
consistently meeting their permit limits. In August of 1981, a local mushroom
processor began batch discharging high BOD wastewater to the POTW at flows
sometimes exceeding 100 gpm. The hydraulic and organic shock loadings
resulted in nitrifier washouts, solids carryover, reduced BOD removal efficiency
and at times total biological process failure. Although the industry was not
measuring their wastewater flow rates at that time, they were the only
significant non-domestic contributor. After factoring out any potential infiltra-
tion/inflow from stormwater flows, the discharge pattern from the industry was
obvious from an inspection of the weekly flow recordings at the POTW.
Figure A-4 illustrates the dramatic effect of the industrial discharges on the
MCWTP influent.
April, 1982
October, 1982
FIGURE A-4
WASTEWATER DISCHARGE AT INFLUENT METERING STATION (MGD)
A-21
-------
As a result of significant time and effort on the part of Maiden Creek Township
Municipal Authority two years ago, the food processor installed a physical-
chemical treatment system which included surge control tanks and aeration. The
system did reduce the solids load and partially mitigated the flow spike problem,
although the surge tanks were not capable of providing complete equalization.
Unfortunately, the great percentage of their organic waste is soluble, so the
pretreatment facility is ineffective in reducing the BOD loading to the POTW.
Additionally, wastewater production far exceeds the 50,000 gpd limit imposed by
their permit, so occasional flow spikes are still evident. The industry has
requested nearly ten times the current flow limit, necessitating the design of a
full secondary system to reduce their waste strength to domestic levels. Such a
system, including a 650,000 gallon aerated equalization basin, is scheduled to go
on-line in mid-1986. In the interim, the municipality has required that the
industry:
• control flow surges;
• meter and record their flows continuously;
• reduce the BOD in the effluent by in-house methods; and
• composite sample their discharge on a regular basis.
Failure to comply with the abovementioned program will result in a shut off by
the POTW, a measure used previously in February, 1985 when the industry's
wastewater was responsible for total process failure at the plant.
A number of operational changes were instituted in May of 1985 to help combat
the high organic loads in the contact basins. These changes included:
• increasing the aeration by using all blowers at the plant, resulting in
an increase in the first stage D.O. from 2 mg/1 to 5 mg/1;
• addition of selective strains of bacteria to increase the rate of BOD
removal;
• recycling the plant effluent to the head of the plant to dilute the
incoming wastewater; and
• reducing the allowable flow from the food processor and closely
monitoring their adherence to the limits.
Since these changes were implemented concurrently, it is impossible to isolate
the individual impacts of each operations change. However, the collective result
was a substantially improved compliance record. There have also been no flow
spikes at the POTW since mid-December, 1985, indicating better flow control on
the part of the food processor.
A-22
-------
MAIDEN CREEK WASTKWATER TREATMENT PLANT
BLANDON, PENNSYLVANIA
Design Flow:
Secondary Treatment:
0.45 aid
Aerated Submerged Fixed
Film (Contact Aeration)
Location:
Population Served:
Southeastern Pennsylvania
2,000
INFLnENT WASTEWATER
Typical (Upactj
SIGNIFICANT INDDSTRIES
Are. Flow, mgd
% Industrial
BOO;, mg/1
SS, mg/l
NH3, mg/1
0.25
20 (60)
350 (900)
ZOO
60
hvduatry
Food Processor
Dental Office
Flowral*
(1000 gpdj
50
negl.
Problem Polhitanta
BOD, Flow surges
HS
PLANT LOADING
Primary CUrlfiert
Overflow Rate, gal/sC/day
Detention Time, hours
Effluent BOD;, mg/1
Effluent SS, mg/1
Secondary CUriflen
Overflow Rate, gal/sf/day
Detention Time, hours
Typical (Djwet)
350 (1,000)
3.75 (1.25)
Z60
100
Tjrpic«l (Op««t)
450 (1,300)
2.8 (1.0)
Contact
Typical (Uptet)
Organic Loading (Ibs BOD5/1000 if/day)
Total Plant Z.8
First Stage 6.4
Detention Time, hours 12
D.O. Level, mg/1 5-10
BOD;, mg/1
SS, mg/1
NH3, mg/1
PLANT PERFORMANCE
Permit Limit
30
30
10/20
Typical (Upset)
15 MOO!
ID (50)
1 (60)
HAW
LAND APPLICATION
Oft
SLUOQE DRYING BEOS
A-23
-------
METRO-WEST POINT TREATMENT PLANT
Seattle, Washington
The Municipality of Metropolitan Seattle (METRO) has had an operational
industrial pretreatment program since 1969. With minor modifications, the
program was EPA-approved in 1981 as one of the first in the nation. Successful
reductions in influent wastewater and primary sludge heavy metal concentrations
during the last five years can, to a great extent, be attributed to implementation
and enforcement of pretreatment standards. As an outcome of this, self-
monitoring by industrial dischargers augmented with year-round spot monitoring
by Metro's Industrial Waste Section has reduced the incidences of toxic upsets in
the anaerobic digesters of the West Point Treatment Plant.
The Metro-West Point Treatment Plant provides primary treatment and sludge
digestion for an average daily wastewater flow of 132 mgd, 4.7 percent origi-
nating from industrial sources. Approximately 70 metal finishing/electroplating
industries discharge to the sewer system in addition to a variety of other
categorical and non-categorical industries. Records of periodic digester upsets
go back as early as 1967, but their occurrences have become less frequent since
1980, coinciding with substantial overall reductions in heavy metal concen-
trations. Past upsets directly linked to toxic metals (generally chromium) caused
increased volatile acid concentrations, increased carbon dioxide content of the
gas produced, and reduced gas production. An October, 1980 chromium spill to
the West Point facility caused a typical upset and resulted in the plant influent
chromium concentration jumping 10 fold to greater than 2 mg/1. Primary sludge
concentrations of chromium reached 710 mg/1, resulting in a 30 mg/1 increase in
digester concentrations above their normal 16-17 mg/1 level. Metro practices
sludge application to forest lands. Application rates had to be decreased during
upsets, although no interference occurred.
Figure A-5 beiow typifies the reduction in metals realized during the 1981-1985
time period. Plant influent chromium levels dropped approximately 55 percent
while the digested sludge concentrations were reduced by more than 40 percent.
The magnitude of these decreases are typical of other heavy metals as well,
averaging 41 percent for chromium, cadmium, copper, lead, nickel and zinc
combined (see the accompanying data sheet). The primary reason for the
reduction of cadmium and chromium concentrations is improved industrial
pretreatment. In addition to pretreatment, a less corrosive city water supply has
also resulted in lower background metal concentrations for the other metals,
especially for copper. The city recently began chemically conditioning its water
in an attempt to extend conduit life.
Success of the Metro Industrial Pretreatment Program can be attributed to a
number of important factors including:
• development of stringent local limits for industrial discharges;
• year-round industrial waste sampling programs supported financially
by industry; and
A-24
-------
• follow-up procedures to industrial waste spills, taking enforcement
action and levying fines when necessary.
Metro has recently implemented the following steps to improve their
pretreatment program:
• information exchange with industries through the use of quarterly
newsletters and personal communication, and
• increasing public awareness of industrial discharge violators by
publishing the names of violating companies in local papers along
with a statement of Metro's enforcement policy.
Chromium Wast Point 1981 to 1985
H (-
H h
H h
Cr
Trgnd
Sludge -
•.
cx^
H h
- o- EFFLUENT LBS/DAY
- •- INFLUENT L8S/DAY
- 7- DD SLUDGE HC/KC
BEST LINE FIT SLUCCI
H h
II 7/11 2/U I/U I/I) t/tj 4/11 ll/t* 5/M IJ/M
T| ma
FIGURE A-5
WEST POINT CHROMIUM CONCENTRATIONS
A-25
-------
WEST POINT TREATMENT PLANT
SEATTLE, WASHINGTON
Design Flow:
Primary Treat c
125 mgd
Location: Weit-Ceatral Washington
Population Served: 600,000
INFLUENT WASTEWATER
Ave. Flow, ragd
7i Industrial
B005) mg/1
SS, rag/1
Cr, rag/I
Typical (Up«et)
UZ
5
160
:e>o
0.05 'Z.OI
Industry
Metal finishing and
electroplitin?
SIGNIFICANT INDUSTRIES
Problem Pollutant*
Flowrate
(mgd)
Cd, Cr, Cu, Ni, Zn
Primary Clarif ton
Overflow Rate, gal/»f/dav
Detention Time, hourj
Effluent BOO?, mg/1
PLANT LOADING
Typical (Upset)
1080
1.55
75-110
TO-90
Digested Sludge Metal Concentration*
Cadmium, mg/kg
Chroiiium, rug/kg
Copper, mg/kg
Nickel, mg/kg
Lead, nig/kg
1981 Level
45
430
1300
160
300
19S5 Level
28
350
'00
1ZO
400
PLANT PERFORMANCE
BOD:, m^ '1
Permit Limit Typical (Upset)
Summer Winter Summer Whiter
'.35
35 110
55 '30
5.0? <0.05
75
iD
MAW
WAtTIWATK
«*V*^*^HB»WM
A —*^ PRIMARY
BAR AERATED ~~
•CftCCN* QfMT CHAUMR*
(4)
x \
CHLORINE
^ CONTACT
(2)
J
EFFLUENT
LAND
APPLICATWH
CENTRIFUGE
THICKENINd ANAEROBIC
CENTRIFUQE
OEWATEHINfl
(3)
A-E6
-------
NEUSE RIVER WASTEWATER TREATMENT PLANT
Raleigh, North Carolina
The Raleigh case study illustrates the need for continuous survey and monitoring
even after the implementation of an industrial waste program in any dynamic
population center. In 1976, the 30 mgd Neuse River Wastewater Treatment
Plant (NRWTP) went on-line to replace the overloaded 16 mgd Walnut Creek
plant. In the early 1960's, influent BODs exceeded 300 mg/1 at Walnut Creek,
with the effluent ranging from 35 to 55 mg/1. These effluent levels violated the
Walnut Creek Plant permit, established by the state in order to protect the
quality of the Neuse River, which was used as the raw water source for the City
of Smithfield located downstream of Raleigh. Industries were encouraged to
conserve and recycle wastes, resulting in a Z50 mg/1 influent BOD by the
mid-1960's. The City's first Sewer Use Ordinance was enacted in 1972, with
continual modification to comply with changes in the federal regulations. The
net effect is a current influent BOD consistently below 200 mg/1, despite an
industrial flow volume representing 25 percent of the plant flow.
The only significant industrial discharger of metals to the Walnut Creek plant
was a large electroplater whose occasional plating bath dumps were not
prohibited by a sewer use ordinance during the 1950's. Digester upsets
(decreased gas production) and high sludge metals content were traced to this
particular industry. Since dried sludge was being made available to the
community for landscaping purposes at the time, concern for the metals levels
prompted adoption of a proposed ordinance which directed the industry to
construct a physical-chemical pretreatment facility.
Two other metals-related industries have been responsible for high sludge metals
since the construction of the NRWTP. In the current facility, wet sludge is land
applied to farmland adjacent to the POTW, hence metal content is critical. In
each case (an electroplater and a printed circuit board manufacturer), the
industries were discharging levels of Cr, Ni, Zn, Pb and Cu sometimes in excess
of 1,000 mg/1, with highly variable effluent pH, and were uncooperative in
dealing with the City of Raleigh. Fining the former industry $ 1,000, and
threatening the latter with the same, provided sufficient incentive to install
pretreatment.
In the early 1980's, a producer of amino acids for Pharmaceuticals in Raleigh
discharged slug loads totaling 1,000 Ibs of NH3 to the POTW each day.
Fortunately, an activated sludge system had been constructed for their facility
for BOD reduction, which possessed sufficient capacity to nitrify their
wastewater to an ammonia concentration of 50 mg/1. On one occasion, the NH3
levels became toxic to the lU's activated sludge pretreatment, resulting in a
gradual loss of nitrification at the POTW. Rapid identification of the NH3
discharge by City personnel preserved the POTW nitrifier population, which was
subsequently used to re-seed the industry's activated sludge with a viable
nitrifier population for a speedy recovery. The rapid response prevented the
monthly effluent NH3 levels from exceeding the permit limit, despite high daily
concentrations following the incident.
A-27
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A dairy product manufacturer who cleans the stainless steel tanker trucks on-
site had previously discharged these wastes directly to the sewer. Average BODs
of 10,000 mg/1, with occasional values in the 30,000 to 40,000 mg/1 range were
typical, often resulting in effluent BODs in excess of the 6 mg/1 (12 in winter)
allowed for the POTW. Working with the North Carolina State University, a
vacuum recovery system was developed and a market identified for the collected
whey waste. The effluent BOD now averages 2,000 mg/1, still resulting in a high
surcharge payment, but no permit violations at the POTW.
An unusual case at the NRWTP was the discovery of high zinc levels (1,000 mg/1)
in the discharge from an office building with no manufacturing component.
Through discussions with maintenance personnel, the City of Raleigh discovered
that the contaminated discharges corresponded to floor stripping activities in the
building. They learned that a Zn-based floor wax had been used, and stripping an
entire office building over the course of a week discharged enough Zn to the
POTW to significantly raise the level in their sludge. The elevated zinc level
threatened to interfere with the POTW's ability to dispose of its sludge.
The Raleigh plant is currently under construction to increase the hydraulic
capacity from 30 to 40 mgd, with an additional expansion to 60 mgd planned for
the near future (the schematic shown on the next page is for the 40 mgd
facility). The rapid growth of this community will continue to bring with it a
variety of challenging new industrial wastewaters with, in some cases, unpredict-
able impacts on the POTW.
A-28
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NEUSE RIVER WASTEWATER TREATMENT PLANT
RALEIGH, NORTH CAROLINA
Design Flow: 40 tngd Location: Central North Carolina
Secondary Treatment: Actirated Sludge Population Served: 195,000
(Extended Aeration)
DJFLUENT WASTEWATER
Ave. Flow, rngd
^ Industrial
BOD$, mg/1
SS, mg/1
Typical (Upset)
25
Z=,
165 :350)
Industry
Electroplaters, Metal
Finishers 15)
Pharmaceutical
Dairy
Snack Foods
SIGNIFICANT INDUSTRIES
Flowrate
(1000 gpd)
750
•100
no
100
Problem Pollutants
Cd, Cr, Cu, Ni, Pb, Zn, Cn", Fe, pH
BOD
BOD
Primary Clarifiers
Overflow Rite, sjal'sfriav
Detentioi Time, hours
Secondary Clarifiers
Overflow Rate, gal'sf/4av
Detention T;me, !iours
SVI, iil/gm
Effluent BOD;, m?/l
Effluent SS, m«/l
Effluent NH3, rag/1
PLANT LOADING
Typical (Upset) Aeration Baiini
650
3.0
Typical (Up«et)
3.2
130-200 :350I
F/M, Ibs BODs/lbs MLSS/day
MCRT. days
MLSS, mg/1
Detention Time, hours
Return Flow, ^o
C.O. 'Lfvel, mg.'i
Multi-Media Filters
Hydrauhc loading, gpm.'sf
PLANT PERFORMANCE
Permit Limit
Summer Winter
Typical (Onset)
Typical (Upset)
0.08-0.10
1Z-ZO
2.500
15
50
Typical (Upcet)
2.5
BCD;, mg/I
SS. T"; ',
NH3. mg".
o 12 51151
30 30 4
3 t 1.5 (51
NAW
WA«tBWATCM
•AM »CREEM»
AND
«MT CHAUMR_
EFFLUCNT
LAND
APmjCATIOM
-------
NEWARK WASTEWATER TREATMENT PLANT
Newark, Ohio
The Newark Wastewater Treatment Plant (NWTP) had been in substantial non-
compliance with its 1981 NPDES permit from the beginning of 1983 until the
middle of 1984. This consistent violation had resulted primarily from increased
waste loads on the POTW from industrial sources. Between 1979 and 1984, the
percentage of industrial wastewater increased from 12 to 22 percent by volume,
with influent BOD increasing from 220 to 330 mg/1, while suspended solids
increased from 200 to 350 mg/1. To complicate the non-compliance problem,
four separate ammonia discharge episodes occurred from August to October,
1983 which resulted in both the loss of activated sludge viability (interference)
and the pass-through of the NH3 and the subsequent killing of 80,000 fish in the
Licking River. The fish kill precipitated the submission of Verified Complaints
to the Ohio EPA on August 6, 1984 by the Black Hand Gorge Preservation
Association, against the City of Newark and the NWTP. Following an
investigation, the Ohio EPA issued Director's Final Findings and Orders,
specifying a compliance schedule and interim discharge limits for the POTW
until a planned facility upgrade is completed by July 1988.
There are two significant industrial contributors to the NWTP who were also
issued Director's Final Findings and Orders in May, 1985. A fiberglas insulation
manufacturer had been discharging high concentrations of phenol (2-5 mg/1) and
NH3 (up to 500 mg/1), with occasional spills of formaldehyde into the collection
system. The activated sludge bacteria were acclimated to the phenol in the
wastewater, but were susceptible to interference from shock loadings of the NH3
and formaldehyde. Fortunately, the industry was responsive to the problems of
the NWTP, and instituted a corrective program to:
• conserve and recycle plant flows, which have reduced their discharge
by 60 percent (from 1.22 to 0.45 mgd) over the past two years;
• construct an aerated equalization basin to air-strip phenol and
distribute diurnal fluctuations; and
• construct a pretreatment facility for their landfill leachate.
The POTW is still subject to occasionally high NH3 loads from the industry,
which is currently the only identifiable cause of isolated interference problems
in the plant. The municipality and industry continue to work cooperatively to
resolve this problem through the implementation of a spill prevention and control
program. Additionally, the renovated POTW will use some of the existing
clarifier tankage for off-line storage in the event of future spill episodes.
The replacement of coarse bubble aerators with fine bubble equipment in mid-
1984 significantly improved BOD removals and the NWTP compliance record.
Nitrification, which did not occur previously, now takes place in the last two
aeration basins, because of the improved carbonaceous BOD (CBOD) removal in
the initial basins. The only incident of non-compliance with the interim permit
in 1985 resulted from an NH3 discharge from the fiberglass manufacturer. In
A-30
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this case, even though the average monthly BOD measured 29 mg/1, the
carbonaceous component was less than 10 mg/1. The final permit will have a
more stringent NHj requirement and will also designate CBOD as a permitted
parameter.
A second major industry is a dairy which came on-line in 1976. Initially, the
dairy stored whey waste in a silo and typically bled it into the sewer system.
The discharge was high in both BOD and suspended solids (2,000 mg/1), and would
occasionally be batch discharged to the POTW, resulting in a shock loading to the
activated sludge and violation of the NPDES permit limits. The industry has
since installed a reverse osmosis treatment system for the whey waste which has
reduced the solids and organic loading to the plant.
The only categorical industry that currently discharges to NWTP is an electro-
plater who constructed a metals removal system in conformance with federal
pretreatment regulations. In the past, dewatered sludge had been applied to corn
fields adjacent to the plant property. However, when heavy metals were
detected in seven of ten monitoring wells, Newark began hauling liquid sludge
off-site. The planned facility upgrade will include installation of belt filter
presses, so that the existing sludge (with acceptable levels of heavy metals) can
once again be dewatered and more economically hauled off-site to farm land.
A-31
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NEWARK WASTKWA-TCR TREATMENT PLANT
NEWARK, OHIO
Design Flow:
Secondary Treatment:
S.O (12.0 Hydraulic) tngd
Activated Sludge
(Conventional)
Location: Central Ohio
Population Served: 41,000
INFLUENT WASTEWATER
Ave. Flow, rogd
% Industrial
BODs, mg/l
SS, m?/l
Typical (Upwt)
305
Industry
Fiberglass
Dairy
Electroplater
SIGNIFICANT INDUSTRIES
Problem Pollutants
Rowrate
(1000 gpd)
PhenoL, NHj, Formaldehyde
3OD, Phosphorus, SS
Cr. Cd. Pb, Ni, Zn, Cvanide
Primary Clarifien
Overflow Rate, gal.'sf'lav-
Detention Time, hours
Effluent BODj, mg/1
Eft'.uent SS, mg/1
Secoodary Clarifien
Overflow Rate, ?al'sf iav
Detention Time, hours
S\l, Tll/yill
Typical (Upwt)
560
3.1
i?4 :zso>
147 iZUI
Typical
5:0
3.7
0 '350'
PLANT LOADING
Aeration Baiini Typical (Upset)
F.-M, Ibs BODj/lbs MLSS/day O.Z5 '0.4!
MCRT, -layi 5-i>
MLSS, mg/1 ?,GOO
Detention Time, hours b.3
Returi F'.ow, " 50
3.O. Level, rne.'l 2.0
PLANT PERFORMANCE
Permit Limit
Typical (Upset)
•"-"•;. T = \ Summer1
RAW
WASTEWATER
WAS
V7—
AERATED
QRIT
CHAMBER
M
PRIMARY
CL APIFIERS
(7)
AS |
*,
AERATION
(fl)
ANAEROBIC^
I f ( DIGESTERS
(3)
LIQUID
SLUDGE
HAULING
FIKrfAL
EFFLUENT
A-32
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NORTH SHORE SANITARY DISTRICT GURNEE PLANT
Gurnee, Illinois
The Gurnee Plant of the North Shore Sanitary District (NSSDGP) receives an
average daily wastewater flow of 12.4 mgd from a variety of sources. Those
sources include a major naval installation, domestic sewage discharges,
secondary effluent from the District's North Chicago Sewage Treatment Plant,
and other industries which contribute 17 percent of the total flow.
Since startup in 1976, the NSSDGP has experienced periodic failures at achieving
nitrification in the two-stage activated sludge system. The failures to achieve
nitrification to the ammonia levels of the District's NPDES effluent limits have
also, at times, been accompanied by general process upsets which have resulted
in effluent SS and BODs violations. One of the major industrial contributors to
the Gurnee Plant, a pharmaceutical manufacturer discharging an average flow of
750,000 gpd, has similarly experienced upsets of its own activated sludge
pretreatment system which have resulted in violations of the District's local
sewer use ordinance. It was initially believed that the observed interferences at
the NSSDGP were the result of the discharge of filamentous organisms and other
solids by the manufacturer. The initiation of in-plant solids control methods
(which significantly lessened the quantity of solids entering the industrial
wastewater pretreatment system) and pretreatment system upgrades did not,
however, eliminate interferences at the NSSDGP.
In 1980, District personnel began to suspect that the presence of a nitrification
inhibiting antibiotic, erythromycin, in the pharmaceutical wastewater was the
main cause of the process upsets at the NSSDGP. By 1983, test and control
bench-scale activated sludge reactors were placed in operation and the effects
of the pharmaceutical wastewater and erythromycin on the NSSDGP were
investigated. A bioassay test for the presence of erythromycin and other
nitrification inhibitors was also developed, along with a Direct Insertion
Probe/Mass Spectrometric technique for confirmation. The results of the bench-
scale testing indicated that the presence of soluble and/or solid constituents of
the pretreated pharmaceutical wastewater inhibited nitrification and, at high
levels, could completely suppress nitrification. Additionally, it was found that
although erythromycin inhibited nitrification, acclimation to low concentrations
of erythromycin could occur in the absence of extreme concentration
fluctuations.
During January of 1984, an observed average industrial pretreatrnent effluent
erythromycin concentration of 53 mg/1 with mass loading fluctuations of greater
than two orders of magnitude completely inhibited nitrification in the^Gurnee
Plant. The resulting BODs and SS concentrations were as high as 26 mg/1 and
67 mg/1, respectively. Lower concentrations of erythromycin in the absence of
such strong concentration fluctuations did not interfere with the performance of
the Gurnee Plant during August of 1984, with average effluent BODs and SS
concentrations of 11 mg/1 and 8 mg/1, respectively, and effluent ammonia
concentrations ranging from 0.4 mg/1 to 1.5 mg/1 as N. Experience at the
Gurnee Plant and with the bench-scale test systems has also indicated that a lag
period of two to three mean cell residence times is required before the effects
A-33
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of erythromycin on the activated sludge process become apparent. Erythromycin
also was found to disrupt the settling of the first-stage carbonaceous organisms.
Measures undertaken by District personnel to lessen the effect of the
pharmaceutical discharge on plant performance have included:
• The addition of inorganic coagulants to aid primary clarifier
performance;
• the addition of polymer to the first-stage activated sludge system,
• daily bacterial (staphylococcus aureus) bioassays of industrial
wastewaters for the presence of inhibiting substances; and
• the development of an ordinance governing the discharge of
erythromycin to the NSSDGP.
Since passage of the ordinance in November, 1985, in which the discharge limits
for erythromycin were established, the NSSDGP has substantially been in
compliance with its NPDES permit and ammonia levels of 0.25 mg/1 to 1 mg/1 as
N have been consistently achieved.
A-34.
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NORTH SHORE SANITARY DISTRICT GORNEE PLANT
GURNKZ, HJJONOE
Dciign Flow:
Secondary Treats
13.« mgd
Activated Sludge
(Two-Stage, Uodlfied-Contact}
Location:
PopuUtion Served:
Northeastern Illinois
45,000
IWL0ENT WASTEWATER
Are. Flow, mgd
n Industrial
BOD;, mg/1
SS, mg/1
NH3, mg/1
Typical (Opsct)
1Z.4
37
140
180
15
India try
Pharmaceutical
Electroplating
Chemical
Nonferrous Metal>
Military Initallation
SIGNIFICANT INDUSTRIES
Flowrate
(1000 gpd)
750
100
170
90
3,500
Problem Pollutant*
Antibiotics, SS
Cu, CN
Organic!
W
pH
PLANT LOADING
Prinary Clarificn
Overflow Rate, gal/if/day
Detention Time, houri
Effluent BOD5, mg/1
Effluent SS, mg/1
Fint Staf« Clarlfien
Overflow Rate, gal/sf/day
Detention Time, houri
Second Stag* CIvifien
Orerflow Rale, gal/if/day
Detention Time, hours
Typical (Upaet)
695
2.7
100
100
TfpicaJ (Dpset)
780
2.S
Typical (upacl)
645
3.1
Fint Stage Aeration Basins Typical (Uptet)
F/M, Ibl BOD5/lbi MLVSS/djy 0.95
MCRT, diyj 7
MLSS, mg/1 3000
Detention Time, houri 4.Z
Return Flo*, ft IS
D.O. Level, mg/1 2.5
Second Stage Aeration Baaisu Typical (Upset)
F/M, lb» NH3-N/lbs MLVSS/day 0.07
MCRT, days 13
MLSS, mg/1 3500
Detention Time, hours 5.8
Return Flow, % 50
D.O. Levels, mj/1 Z.S
BOD;, mg "
SS, mg/1
NH3, mg 1 summer)
PLANT PERFORMANCE
Permit Unit
10
1Z
1.5
Typical (Dpeet)
5 (17)
5 (23)
0.5 (15)
HAW
WAtTCWATIN
TO
CENTRALIZED
DEWATCniNO
FACILITY
A-35
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PASSAIC VALLEY WASTEWATER TREATMENT PLANT
Newark, New Jersey
Coping with industrial waste discharges to a 300 mgd POTW in a highly
industrialized area is a challenging task. The Passaic Valley Sewerage
Commissioners (PCSC) maintain an industrial waste control staff to monitor
nearly 400 industries that contribute 20 percent of the wastewater volume and
50 percent of the waste strength. The PVSC performed their first Industrial
Waste Survey for database development in 1972, and adopted a set of Rules and
Regulations (including local limits) in 1976. By 1982, a comprehensive system
consistent with the Federal Clean Water Act of 1977 had been adopted, which
established uniform user fees for mass and volumetric loadings in the Passaic
Valley plant.
The influent wastewater to the POTW is considered a high-strength waste, with
typical BOD and TSS values of 290 and 450 mg/1, respectively. Despite the
strength of the influent, the plant is close to meeting the 30/30 NPDES discharge
limits, even though the primary clarifiers are not scheduled to go on-line until
later this year (1986). The high percentage of industrial flow volume is
responsible for the high influent BOD, and hence an interference exists, although
the number of industries makes it impossible at this time to determine which are
responsible for the interference. The PVSC believes that the addition of primary
treatment coupled with the economic incentives for pretreatment created by the
user charge system will reduce the effluent to consistently below the limits.
The individual constituents of concern to the PVSC fall into three general
categories:
• metals
• flammables
• fibers
The sources of heavy metals are chemical manufacturers, platers and tanneries.
One of the smaller (30,000 gpd) chemical companies had been identified as a
significant contributor (120 Ibs/day) of mercury to the POTW. Although the
mercury level of 50 ug/1 at the influent was not inhibitory to the activated
sludge, the concentration of mercury in the sludge limited the municipality's
disposal options. It is anticipated that ocean disposal of sludge will not be
permitted much longer, which will require the PVSC to incinerate. The Federal
Air Pollution Standards limit the mercury discharge to 3,200 g/day, which
translates into a local limit of 0.4 Ibs/day in the wastewater from the industry in
question. The chemical company responded by isolating the relevant process
streams and utilizing a batch recovery system for the mercury, reducing the
discharge from 120 down to 5 Ibs/day. When ocean disposal is formally
eliminated as a disposal option, the company can employ carbon treatment for
removal of the remaining mercury.
The oxidation of trivalent chromium to the hexavalent form in a POTW sludge
incinerator is a problem caused by the chromium-laden discharge from various
industrial users. An additional problem caused by the tanning industrial category
A-36
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is the clogging of local sewers that results from hides being inadvertently
discharged from the companies. Similar clogging problems existed at the
pretreatment plant due to the balled-up fibers from the pulp and paper
manufacturers which close off sludge return lines, orifices and nozzles. This
condition improved substantially when the moving-bridge primary clarifiers were
placed in service in December, 1985.
The Passaic Valley "plant had a unique problem with high concentrations of
flammable materials in the influent wastewater. The lower explosive limit (LEL)
is defined as the "lowest concentration of a combustible substance in air through
which a flame, once ignited, will continue to propogate". When a wastewater
approaches 50 percent of the LEL, it is important that it not be discharged into
the sewer collection system. The pure oxygen process has a control built into
the system which vents all oxygen away from the activated sludge treatment
process when high LEL is detected. Since the venting of the oxygen reduces the
treatment efficiency it can result in a permit violation as well as creating a
health hazard.
The PVSC instituted a three-part program in October of 1984 to mitigate the
problems of flammables:
• required industries using or manufacturing solvents which come in
contact with discharged wastewater to install LEL detection
instruments, and to provide pretreatment to isolate the flammables if
high LELs were detected;
• surveyed other industries which used solvents but had no such
discharge to determine if a potential existed, requiring necessary
control mechanisms; and
• monitored the collection system more closely for illegal dumping of
such chemicals.
Representatives of Passaic Valley made it clear that a cooperative attitude on
the part of industry was an important factor in successful mitigation of
interference problems. In fact, it was the local pharmaceutical manfacturer
that conducted the research resulting in the type of LEL instrument
recommended by the Advisory Committee when the LEL regulation was adopted.
A-37
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PASSAJC VALLEY WASTCTATW TUATVKNT PLAMT
Krwwk, Kww;
Design Flo*:
Secondary Tr*ala*ai:
JJO
Location:
Population S«r»«a:
A.J,
1.
DtrLOKNT WASTCWATTR
SIGNIFICANT DCDOSTUES
AT*. Flow, ngd
1 Industrial
BOD;, mg/1
SS, mg/1
(Open)
:so
19
190 (500)
4iO(7iO>
Pulp tnd P«p«r
6 Xyltnt, Toluen«, HUM*
L.5 Cr
0.5 Cd, Cr, Kg, Pb
PLANT LOADING
Haarr CUrlftan
Overflow Rut, gll/>(/d*f
D«(«ntidn T(ai<, houn
E(nu«ol BOD;, mg/1
E(llu«nt SS, mg/1
"tttmtti> CUriAcn
Rait, gal/if/
D«t«otloo Tlra«, houn
SVI, ml/gtn
1,100
Z.B
;zs
H5
Tfpicai (DpMt)
410
5
65
F/M, Ibt BOD;/1bi MLSS/daf
MCRT, dar«
MLSS, m(/l
Detention Tin*, houri
R«turn Flow, %
D.O. Lartl, m|/l
0.6
5
1,800
1.6
JS
SS,
, mf/1
PLANT PXJtrORMANCS
Pwmit Llailt
30
30
Typical (0*Ml)
i5 1401
Z5 (601
RAW
WA3TEWATER
HAS
"I
I
QUIT
CHANNELS
)XYQENATION
BASINS
0)
1
SECONDARY
CLARIFIERS
(12)
FINAL
EFFLUENT
(OCEAN)
3LUDQE
THICKENERS
(12)
. OCEAN
OUPOtAL
A-38
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SIOUX CITY WASTE TREATMENT PLANT (SCWTP)
Sioux City, Iowa
The Sioux City Waste Treatment Plant (SCWTP) treats a combined industrial and
municipal wastewater average flow of 13.5 mgd and discharges to the Missouri
River. More than 140 industries were identified by an industrial survey as
potential sources of wastewater. Of these, four are categorical metal finishing
or electroplating industries and, as of recently, eleven industries contributed
significantly to the suspended solids, BOD and oil and grease discharged to the
SCWTP. Although the total volumetric load of the industrial wastewater is
typically less than 10 percent of the total flow, the industrial organic loads to
the plant account for greater than 50 percent of the observed loads.
The SCWTP has experienced two separate incidents in which industrial
discharges have interfered with normal plant operations. Isolated slug loads of
zinc were experienced by the SCWTP in March and again in April of 1984.
Levels as high as 16 nog/1 Zn were observed in the treatment plant influent and
both slug-load incidents resulted in an upset of the activated sludge process and
violations of the NPDES discharge limits. Effluent BODs concentrations
exceeded 60 mg/1 and effluent suspended solids concentrations in excess of
200 mg/1 were observed. The investigation of the first slug load of zinc was
somewhat hampered by the lack of in-house capabilities for metals analysis and
the first indication of a contamination problem was the process upset itself.
Upon confirmation of the nature of the interference, a temporary system for the
continuous addition of lime to the primary clarifiers, which would result in the
precipitation of subsequent slug loads of zinc, was installed and operated until
such time that frequent and periodic monitoring and analysis of the influent for
metals could be performed at the SCWTP.
The source of the metal discharge was identified from the City's industrial use
survey and from samples of wastewater and solids collected at specific locations
in the wastewater collection system. The floor drain at the manufacturing
facility through which the zinc discharges occurred was disconnected from the
sanitary sewer. In addition to the process upsets, several years accumulation of
sludge held in storage lagoons and slated for disposal by land application became
contaminated with zinc. Upon receipt of special permitting from the State, the
SCWTP was allowed to dispose of the sludge as planned.
In 1985, a pharmaceutical manufacturer came on-line discharging batches of high
strength waste without pretreatment. The strength of the waste ranged from
10,000 to 100,000 mg BOD5/1 and the waste contained high levels of salt and
sulfite. The average BOD5 of the waste was 35,000 mg/1 and the batch dumps
represented 45 percent of the total organic load to the SCWTP. The activated
sludge process was severely overloaded and intermittent depressions of the D.O.
level occurred. It was possible to operate the activated sludge process to
accommodate the severe organic loads, but the process would again be upset
during the weekends when the pharmaceutical manufacturer was not discharging
waste and the organic loads were reduced. Throughout 1985, the SCWTP
experienced severe violations of their NPDES BOD5 and suspended solids
discharge limits. Frequent violations of the pharmaceutical manufacturer's
A-39
-------
discharge permit occurred with respect to the organic strength and daily mass
loading of the waste. The industrial user was placed on a compliance schedule
and continued violations of the discharge permit necessitated actions that would
result in flow equalization and reductions in the levels of methyl mercaptan,
sulfite and sulfide. Presently, all batch waste dumps are transported by bulk to
the SCWTP where they are metered, by SCWTP personnel, into the plant influent
under controlled conditions.
The upset conditions presented in the following table represent conditions
related to the discharge of the pharmaceutical wastewater. The reported upset
conditions represent averages for several months of 1985 whereas the typical
conditions were based on data for 1984 which spanned nine months and included
those months in which the slug loads of zinc were experienced.
A-40
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SIOOX CITY WASTT TREATMENT PLANT
3OU* CITY, IOWA
Design Flow:
Secondary Treatment:
30ni|d
Stodge
Location:
Population Served:
Northwest Iowa
135,000
INFLCENT WASTEWATER
SIGNIFICANT INDUSTRIES
A»e. Flow, mgd
% Industrial
BOD;, mg/1
SS, mg/1
Typical (Cp*eO
13.5
7
380 (6U)
550 (630)
Meat Processing
Pharmaceutical
Metal Finishing
Flo write
(lOOOgpdJ
1,000
70
20
Frouiem FoUtitut*
EOD5, oil and greue, SS
BOD;, methyl mecsptir,, sulf;;e
Zn, Cr, Ni
Primarr CUrlfier*
Overflow Rate, gal/if/day
Detention Time, hours
Effluent EOO;, mg/l
Effluent SS, mg/1
Secondary CUrif ten
Orerflow Rate, gal/if/djy
Detention Time, hours
SV], Di/gn
PLANT LOADING
Typical (Dp«et) Aeration Baaina
577
2.9
220 (3701
240 (2351
Typical CUp*et)
722
3
150
F/M, Ibs BOD5/lb« MLSS/day
MCRT, days
MLSS, mg/1
Detention Time, hours
Return Flow, % .
D.O. Level, mg/~i
Typical (Opaet)
0.2 (0.3)
10
2500
15
40
2.5
BOD;, mg/1
SS, mg/l
PLANT PERFORMANCE
Permit Limit
30
30
Typical (Upset)
34 '371
33 [45i
HAW
FINAL
EFFLuiNT
PM-AIMATIOW
TAKKB
(4)
••LUOQE LAGOON*
A-4I
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TOLLESON WASTEWATER TREATMENT PLANT
Tolleson, Arizona
The Tolleson Wastewater Treatment Plant (TWTP) is a two stage trickling filter
plant that treats a predominantly domestic wastewater from Phoenix, Arizona
suburbs. The successful operation of the TWTP is dependent on the one
significant industrial contributor to the treatment plant, a meatpacker who
processes 1,000 to 1,400 head of beef per day.
The influent to the TWTP could be typified as medium to high-strength municipal
wastewater with average BODs and SS levels being 275 mg/1 and 225 mg/1,
respectively. Approximately 25 to 30 percent of the average organic and solids
loading is contributed by the meatpacker average at levels of 1,100-1,600 mg/1
BODs and 700-1,200 mg/1 SS, for wastewater flows of 0.8-1.0 mgd. In general,
the domestic /industrial waste stream BOD5, and SS can both be treated to below
10 mg/1, well within the 30/30 discharge limits. However, in the past the
meatpacker has upset the treatment process by slug discharging blood or other
high strength organic slaughter by-products with BODs and SS levels of up to
2,200 mg/1 and 1,375 mg/1, respectively. Prior to 1982, these upset conditions
would last for several days and result in weekly and monthly effluent suspended
solids of 30-40 mg/1, in violation of permit limits.
Treatment upsets have diminished in frequency and intensity since 1982 for two
reasons:
• A legal contract with the meatpacker limits flow to 0.8 mgd,
to 10,675 Ibs per day (1,600 mg/1) and SS to 6,670 Ibs per day
(1,000 mg/1), and provides for fines or disconnection if these limits
are exceeded, and
• Improved treatment plant process monitoring has enabled operators
to better detect, and thus act on, a potentially upsetting condition.
The contract with the meat packer attempts to prevent waste blood from being
stored for more than about eight hours at a time before discharging to the sewer.
Prior practice resulted in blood being held back for up to a week at a time before
being discharged all at once.
Primarily through trial and error, the operators of the TWTP have established
several operating parameters that help them in detecting upset conditions in the
plant. The depth of sludge in the primary clarifiers is monitored closely; a high
or rapidly increasing sludge depth is indicative of upset conditions and is caused
by the high solids content of the meatpacking waste. The mixed liquor in the
solids contact basin following the second trickling filter is monitored closely as
well, with levels above 500 mg/1 signaling possible problems. Mixed liquor
A-42
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concentrations of 1,500 nag/1 generally result in effluent suspended solids of
greater than 30 mg/1. To remedy an upset condition, primary sludge pumping
rates are manually increased above their normal levels to reduce the solids
inventory and prevent escape in the effluent.
A-43
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TOLLESON WASTEWATKR TREATMENT PLANT
TOLLESON, ARIZONA
Design Flow:
Secondary Treatment!
Z Stage TricUlnc FUter
vitk Solid* Coo tact
Location: South Central Arizona
Fopulalion Served: 65,000
INFLUENT WASTEWATER
Ave. Flo*, mgd
% Industrial
BOD,, mg/1
SS, mg/1
Typical
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APPENDIX B
INTERFERING SUBSTANCES
CONVENTIONAL
Biochemical Oxygen Demand
Fats, Oil and Grease
METALS AND INORGANICS
Alkalinity
Ammonia
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Chloride
Chromium
Cobalt
Copper
Cyanide
Iodine
Iron
Lead
Magnesium
AGRICULTURAL CHEMICALS
Aldrin/Dieldrin
Chlordane
Chlorophenoxy Herbicides
DDT
Endrin
pH
Suspended Solids
Manganese
Mercury
Molybdenum
Nickel
Nitrogen
Phosphorus
Selenium
Silver
Sodium
Sulfate
Sulfide
Sulfite
Tin
Thallium
Vanadium
Zinc
Heptachlor
Lindane
Malathion
Organometallic Pesticides
Toxaphene
AROMATICS
Benzene
Chlorobenzene
Dichlorobenzene
Dinitrotoluene
Nitrobenzene
PCBs
Toluene
Zylene
B-l
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HALOGENATED ALIPHATICS
Carbon Tetrachloride Methylene Chloride
Chloroform Tetrachlorodibenzodioxins
Chloromethane Tetrachlorodibenzofurans
Dichloroethane Tetrachloroethane
Dichloroethylene Tetrachloroethylene
Dichloropropane Trichloroethane
Hexachlorobutadiene Trichloroethylene
Hexachlorocyclohexane Vinyl Chloride
Hexachloroethane
NITROGEN COMPOUNDS
Acetanilide Dyes
Acetonitrile EDTA
Acrylonitrile Ethylpyridine
Aniline Fluorenamine
Benzidine Hydrazine
Benzonitrile Nitrosodiphenylamine
Chloroaniline Pyridine
Dichlorobenzidine Trisodium Nitrilotriacetate
Dimethylnitrosamine Urea
Diphenylhydrazine
OXYGENATED COMPOUNDS (Acids, Alcohols, Aldehydes, Esters, Ethers,
Ketones)
Acetone Ethylene Glycol
Acrolein Formaldehyde
Adipic Acid Esters Formic Acid
Allyl Alcohol Heptanol
Benzoic Acid Hexanol
Boric Acid Isophorone
Butanol Linoleic Acid
Butyl Benzoate Malonic Acid
Chlorobenzoate Methanol
Chloroethyl Ether Methylethyl Ketone
Cinnamic Acid Methylisobutyl Ketone
Crotonol Octanol
Cyclohexanecarboxylic Acid Polyethylene Glycols
Diethylene Glycol Polyvinyl Alcohols
Ethoxy Ethanol Protocatechuic Acid
Ethyl Acetate Syringic Acid
B-Z
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PHENOLS
Catechol Pentachlorophenol
Chlorophenol Phenol
Cresol Trichlorophenol
Dichlorophenol Trinitrophenol
Dinitrophenol Vanillin
Nitrophenol
PHTHALATES
Dimethylphthalate
Disoctylphthalate
E thylhe xylphthalat e
POLYNUCLEAR AROMATIC HYDROCARBONS
Anthracene Naphthalene
Benzo (a) Anthracene Phenanthrene
Chloronaphthalenes Pyrene
di-Isopropylnaphthalene
B-3
t> U.S. flOVERNMENT PfWnTNG OFFICE: 1»«7- 7 1 6- 0 0 2i 60699
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