United States
            Environmental Protection
                           WASHINGTON. D.C. 20460
                                                         OFFICE OF

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

     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



             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

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

                            TABLE OF CONTENTS

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


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

                             LIST OF TABLES
No.       	Title	              Page

2-1       Metal, Cyanide and Inorganic Compound                       20
           Concentrations Inhibiting Biological
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
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

                             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

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

                              1. INTRODUCTION

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

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.


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

           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

manual addresses  such concerns to only a limited degree, focusing mainly  on
interference as defined in the above-mentioned regulation.


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

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

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

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

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.

                       2. DETECTING 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

            chemically,   physically,   or   thermally   inhibiting   the   treatment

            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.

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 40C, 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

                     industrial discharge practices
                     acclimation of  POTW treatment  processes  to  the specific
                     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.

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

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

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

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.


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.

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

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.

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

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

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

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:

                      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.


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


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

The operational tools available fall into the following categories:

          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
          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

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

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

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.


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

           t     timed sampling with collection in discrete sample containers
                flow-proportioned sampling  with collection in discrete sample
                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

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

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,

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.

                                TABLE 2-1
                                 (in mg/1)
Biological Process
Chromium (Tot.)
0.04 - 0.4
0.05 - 10
0.5 - 10
0.1 - 20
0.1 - 1
0.05 - 20
5 - 500
0.1 - 10
0.1 - 5.0
1 - 5
0.03 - 5
0.30 - 20
0.25 - 1
0.05 - 0.5
0.3 - 20
0.5 - 1.7
2 - 12.5
0.25 - 5
0.01 - 1
Fixed Film
25 - 50
0.1 - 1
0.02 - 1
1.5 - 50
0.5 - 100
0.10 - 4
50 - 250
2 - 200
50- 100
1 - 10
N/A - Not Available

Sources:    U.S. EPA (1981a), Russell, et al. (1983), Geating (1981) and U.S.
           EPA (1986a).

                                TABLE 2-2
                                  (in mg/1)
Compound Type
Agricultural Chemical
Common Pesticides
Chlorinated Benzenes
Nitrogen Compounds
Oxygenated Compounds
Polynuclear Aromatic

0.05 -0.10
5 - 150
0.1 - 5
1 - 500
1ZO- 500
90 - 1,000
5 - 100
50 - 200
500 - 2,500
Biological Process
< 0.1 - 18
0.1 - 100
1 - 10

100 - 870
0.1 - 1
0.1- 100
20 - 1,000
100- 200
0.2 - 100
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)

                                 TABLE 2-3
                              (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

Fume Toxicity       - Build up of toxic fumes          -  Metals
                     - Pose a hazard to human health   -  Pesticides
                                                      -  Industrial solvents
                                                        (benzene, toluene)

                                                  TABLE 2-4
          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
Pin floe in overflow
Ash-like material floating on surface

Straggler  floe (< 1/4" dia) in
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
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)

                                            TABLE 2-4 (Continued)
          Possible Cause
Trickling Filters
  - Filters
  - Clarifier
Rotating Biological
Contactors (RBC)
                              Localized rising sludge

                              Sludge clumps and hubbies rising
                                to surface
Surface ponding


Slime colors

Increased effluent suspended solids

Poor effluent quality


Poor effluent quality

Excessive sloughing

White, stringy biomass

                                           Organic overloads in aeration tank
                                           Septic conditions
Organic overloads, excessive
  biological growth
Organic overloads, anaerobic
Metals, toxic shock

Excessive sloughing due to pH or
  toxic shock loads

Organic overloads, toxic shock
Low D.O., sulfides

Organic overloads, poor pH
Toxic shock, pH fluctuations

First stage organic overloads, sulfides
Septic influent, sulfides

                                           TABLE 2-4 (Continued)
          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
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

                                 TABLE Z-5
                            AND WASTE STREAMS
   Parameters Measured
Conductivity Meter
Density Meter
   gamma radiation
D.O. Meter
   membrane electrode
Flow Meter
   flume, venturi,
   magnetic, weir
Gas Analyzers
Potential (ORP) Meters

pH Meter
 Selective Ion
 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
Dissolved solids

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.

                                 TABLE 2-6
Activated Sludge
Trickling Filters
Anaerobic Digestion
Dissolved oxygen
Sludge solids content
Sludge blanket depth
Dissolved oxygen
Mixed liquor suspended solids
Oxygen uptake rates
Microscopic examination
Sludge volume index

Slime thickness
Influent pH, temperature, HS
Effluent solids content

Dissolved oxygen (each stage)
Soluble BOD (each stage)
Biomass thickness
Shaft weight
Effluent solids content

Solids content
Metals content
Volatile acids/alkalinity
Supernatant solids, NHg
Methane content of gas


   As needed
   As needed
   As needed

   As needed
   As needed

Source:    James M. Montgomery, Consulting Engineers, Inc.

                              TABLE 2-7
                     OF INDUSTRIAL WASTEWATERS

BOD Serial Addition
Packaged Bacteria
Photo Luminescense
Testing Time
5 days
30-60 min.
30-60 min.
15 min.
Equipment Costs
$1,000 - $5,000
$1,000 - $2,000
$5,000 - $10,000
2-4 hrs.
4-8 hrs.
4-8 hrs.
20-40 hrs.
Source:    James M. Montgomery, Consulting Engineers, Inc.

                        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.


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.

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,

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.

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

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

           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.


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

          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-

           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

      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).

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

          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).


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.


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.

                             TABLE 3-1

Akron, OH
Bayville, NJ
Bergen, NJ
Bloomington, IN
Dayton, OH
Forth Worth, TX
Hillborough, FL
Jacksonville, FL
Los Angeles, CA
St. Paul, MN
Toledo, OH
Rubber Mfg.
Water Treatment
Grain Processing
Food Processor
Gasoline Station
Battery Salvaging
Organic Chemicals
Metal Finishing
Naphtha, Acetone,
Isopropyl Alcohol
Sulfides from
high BOD
High and low pH
Sodium Bisulfite,
low pH
Sources:   Busch (1986), AMSA

                                 TABLE 3-2

                      IMPACT ON TREATMENT PLANT
Boise, ID
Cam as, WA
Pulp Mill
Cu, Ni, Zn

upset (2 days)
Camden, NJ
Dallas, TX
Depue, IL
Dye Mfg.
Organic Chemicals
Fertilizer Mfg.
Aniline Biological
upset, sludge
Xylene, Toluene Fouled carbon
Sulfuric Acid Biological
process wiped
Sources:    Busch (1986), AMSA

                                 TABLE 3-3

Central Contra Costa, CA
Louisville, KY
Rockford, IL
San Diego, CA
Electroplating sludge
Cd, Cr, Pb, Zn, CN~
Biological process
wiped out

Treatment plant
out of operation
for 3 months

Hydrogen cyanide
gas production

Sewer explosion
Source:    U.S. EPA (1986a)

                                                                                                TRACE TO
NO _ r




                                                                                COMPOSITI COHKCCTIOK
                                                                                MOQKAM (((TtXT, AQI 2)
                                                                                  JAMES M. MONTGOMERY.
                                                                                  CONSULTIHa ENOINEEAS, INC.
                                          FIGT3RE 3-1


Supervisor inspect*
treatment pltist 1
pbonei key industries
to check iot spills

Source tracked by
sensory or field

Not directly
trackable source

Supervisor contacts
Coast Guard auid,'or
State Water Control
Board if pass*through
is evident
Sampler* set up it
key points in the
service are*
     Samples collected,
     labeled St preserved
     during tracking
Costs invoiced A
treatrneni plar.t
upset billed :D

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
                           rU permit aodified
                           to reflect compliance
                           schedule Se possibly
                           increased monitoring
                  nav ^e terniinated at
                  th-s tirr.e or later
                                           If discharge still
                                          . not m compliance
                                          i permit revoked
                                      FIGURE  3-2

                                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.


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

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.

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:

           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).


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

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

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

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

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.



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.


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.

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

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.


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

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

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:

          orders and compliance schedules
          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

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

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


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.

                                                 TABLE 4-1

                                  BIOLOGICAL PROCESS CONTROL STEPS
   Method of
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

                      Improved toxic pollutant
                      biodegradation and acclimation
Source:    U.S. EPA, 1986a

                                                 TABLE 4-2

                                           CHEMICAL ADDITIONS


Point of
Result Addition
Reduce bulking
Various, particularly
textile and wood
products wastewater
Kills filamentous
Varies, but RAS &
aeration basin
effluent  common
 and Sulfur
Improve biological
treatment and
reduce bulking
High carbonaceous
strength waste
Corrects nutrient
deficient condition
Before aeration
Lime or
Polymers or
Reduce biological
Reduce biological
Heavy Metals
Toxic organics
Raises pH causing
metals to precipitate
Removes toxics and
improves sedimentation
Adsorbs organic
Before primary
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.

                                                 TABLE 4-3

                                 TREATMENT PLANT CONTROL MEASURES
 Primary Clarification

 Activated Sludge

 Trickling Filters


 Rotating Biological
  Contactors (RBC)
Source:    James M. Montgomery, Consulting Engineers, Inc.


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
      Surrey Industrial Community to
      Determine Poienlially Regulated

      Notify Appropriate Facilities to
      Collect Additional Information

      Development Classification Scheme;
      High, Moderate, Low Uisk

      Review all Lidustria! Data to
      Determine Each Facility's

      Develop List of Affected Uaeri
      ft Appropriately Categorize
                                                     ntioo tTogram
     Formally notify facilities to
     develop ASPPs

     Review /approve IU ASPPs

     Issue a control mechanism;  issue

     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

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

Determine Lead Agency for Spill
                                                                                       Formalize and
                                                                                       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
                                                                      (U.S. EPA, 196b)

    POTW notifies
    hauler of
    permit system
POTW random
of load
                                                POTW compliance
                                                action if permit
                     copy of
                     to POTW at
                     time of
                      FIGURE 4-2

                    (U.S. EPA, 1985a)

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,

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.

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.


        TABI.K A 1

Bark Kiver,
Balti-nore, Ml)

Baltimore, MI)
Union Beach, NJ
East Side,
Osw eg", NY
Hamilton Township,
Trenton, NJ
Horse Creek
North Augusta, SC
Hob Moore
Plant Manager
C01) Z88-6900

Herald Slattery
Pl.int Manager
(301) JS4^700
David Knowles
(201) 739-1095
John Mcfirath
Lab Supervisor
(315) 34^-3777
Thomas Andersen
Assistant Superintendent
(609) 890-3540
Stanley Wagher
(803) Z78-1911
Nature of
Kestrii -teil
Sludge disposal
Sewer syst fit
Explosion hazard
permit violations
Organic ov>rload-
pennit violations
Suspended solids
overload - permit
Upset conditions -
permit violations
Biomass inhibition
bulking sludge
I. ab analysis
Visual and sensory
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
BOD, COD, SS Only major
SS, BOD Only major
BOD, SS, Volatile industrial
Organics community
Alkalinity, pll Industrial
SS monitoring
Implemented pre-
treatinent program
              TABLE A-I


Maxim <"rrkt
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

Kdward < 'Uusman
(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
(201) U4-ISOO
A.V. Flores
Project Manager
(712) 279-6169
Sterling Pillow
(60Z) 936-3381
Nature of
Treatment ups'-t dip-
to shock loading -
permit violations


Sludge cont.vuinat ion

Treatmpnt upsot d.ie
1 o shock load MHJS -
permit viol.it urns
Nit rif ic.at ion
inhibition, process

Treatment ups-i -
pfrmit violation

Treatment upset due
to shock loadings -
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

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)
          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

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.

                                    BACK RIVER WASTEWATER TREATMENT PLANT
                                               BALTIMORE, MARYLAND
   Design Flow:
   Secondary Treatment:
110 mgd
Trickling Filter* and Activated Sludge

Ave. Flow, mgd
% Indus trill
BODj, rag/1
SS, tug/1

Typical (Dpiet)
180 1270)

Metal Plating M Z)
Auto Mfr.
Paint tnd Chemical
Waste Haulers

Cr, Cu, Ni, Zn


Ethyl benzene, toluene, xylene
Cd, Hg
Solvents, petroleum

                                                   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)
            Typical (Upset)

  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)

Typical (Upset)

   150 (2001
   UO '13d
                        30^;, rr.g/1
                        SS, mg/1
                    PLANT PERFORMANCE

                             Permit Limit

               Typical (Upset)

                   40 (50)
                   10 1531
           AV WASTEWATER
                                                                  BETHLEHEM STEEL
                                                                  COOLING WATER
                                                                                        FINAL EFFLUENT

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.

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.

           !.-(_  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

                                    PATAPSCO WASTEWATER TREATMENT PLANT
                                              BALTIMORE, MARYLAND
   Design Flow:
   Secondary Treatment:
70 mgd
ActITted Sludge (Pure Oxygen)

Ave. Flow, ragil
t Industrial
BOD";, raz/1
SS, mg/l
TOX, %
Typical (TJpMt) Industry Imgd) Problem PoUutanti
i2 Chemicals 1.0 Insecticides, Volatile*, phenols, metaU
165 13ZO) Metal Finishing C.13 pH, solvent^, raetali
325 (470)
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
            Tfpica! (Upsst)
                                         F/M, Ibs 3OD5/lbs MLSS/day
                                         MCRT, clays
                                         MLSS, mg/l
                                         Detention Time, hours
                                         Reijrn Flow, "
                                         D.O. Level, mg,'.
lypicai (Upseti


                        55. mg.M
                        Total-P, mg. !
                                               PLANT PERFORMANCE

                                                        Permit Limit
                                                                                Typical (Upset)

                                                                                    : i 40'
                                                                                    :; 40'
                                                                                             FINAL EFFLUENT



                                                                           ASH TO


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

                                  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.

                                   BAYSHORE REGIONAL SEWERAGE ADTHORTTY
                                               Union Beach, New Jerey
   Diign Flow:
   Secondary Treatment:
    Activated Sludge
    (Modified Contact Stabilization)
                   Location:           Eastern shore
                   Population Served:   80,000

                     Typical (Op*et)
  Ave. Flow, ragd
  % Industrial
  BOD;, mg/l
  55,  mg/1
220 (380)
250 UOO)

Flavorl it  Fragraj-.ces
(3 industries)
                                                                 SIGNIFICANT INDUSTRIES
                                          Flo write
                                          (1000 gpd)

                                            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)

                  150 (250)
                  100 (ZOO)
               Typical (Upset)

                  IZS  (500)
                       Aeration Basins

                         F/M, Ibs BODj/lbs MLSS/day
                         MCRT, days
                         MLSS, rag/1
                         Return Flow, "a
                         Detention Time, hours
Typical (Dpset)

  0.65 (1.25)

                       BOD5, mg/1
                       SS, rag/1
                       D.O. rog/1
                                              PLANT PERFORMANCE

                                                       Permit Limit
                                     Typical (Upset)

                                        35 '4?0)
                                        2- .ir.
                                                                                              ASH TO
                                                                                              SLUDGE LAGOON

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

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.

                                     EAST SIDE SEWAGE TREATMENT PIJUCT
                                               OSWEGO, NEW YORK
Design Flow: 3 mfd
Secondary Treatment: Ping or Step Feed
Activated Sludge
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
New York

Industry (1000 gpd) Problem Pollutant*
Piper Mill 1,200


Primary Clarifien

  Ortrflow Rate, gal/if/iiy
  Detention Time, hours
  Effluent BOD$, tng/1
  Effluent SS, mg/1
                                                 PLANT LOADING

                                      Typical (Opaet)             Aeration Baiin*
                                             Paper Mill
F/M, Ibi BOD5/lb MLSS/day
MCRT, days
MLSS, mg/1
Detention Time, hours
Return Flow, %
D.O. Level, mg/1
                                                     Typical (Upaet)

                                                          7 ;3i
                                                         2,000  1300)
                                                         i5  - 45
Secondary Clarifien

  Overflow Rate, gil/if/diy
  Detention Time, hours
  SVT, ml/gm
Typical (Upel)

   ICC (10001
                                              PLANT PERFORMANCE

                                                      Permit Limit
                                                             Remainder of
                                                  Summer        Year
                                                 Typical (UpeO
BCD;, njg/1 30 45 20 UiOl
SS, oeg/1 30 70 25 (3001
j icMlJ" t
! I I _
1 1 CHlOMMt
1 L_

1 ,1 r*nui 1 1 I 1 j T t
j U lAamt  *. CLAHtfitm _
( r\ '"* LJ F '*'
^> pLBiF(if j 	 1  r1
i _J 1  	 "**_ -J
	 L..___-_I__^A( _ 	 J
X^'"^/ f~^-\ *=~~-~-^ " LAKOfK.1


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

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.

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

           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;

           hiring of  four  more people  plus the purchase of  a  vehicle for an
            extensive  industrial sampling program.

                                                  Teuton, New Jeney
   Design Flow;
   Secondly Treatment:
       16 mgd
       Trickling Filter and RBC
                   Population Served:
                Central Western Borde
                                                                   SlfiNOTCANT INDUSTRIES
  Ave. Flo-*, rngd
  "a Industrial
  BOH5, mg/l
  SS, mg/l
Typical (Opetl

    ID lejti
   340 '500'
   L6C :400!

^lectroplaters ''21
(1000 gpd)

          Problem Pollutants

SCO, phenol, ethyl beniene, toluene, xyier.e
Cd, Cr, Zn, Mi
Primary Clarifieri

  Overflow  Rate, g
  Detention TiTEe,
                              PLANT LOADING

                   Typical (Opet)              Trickling FUtert
                    S30, IbO.  iZO
                     v.s, A.?,, ;.ti
                                                              TyptcaJ (Dpet)
                          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
                         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:
                                      Typical (Upset)

                                          45 1100
                                          :o .5-0;
                                          :: 3-r

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

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 CREKK POLLUTION CONTROL FACUITY
                                            Alke* County, South Carolina
   Deiign Flow:
   Secondary Treatment:
Extended Aeration
Activated Sludge
Population Served:
                                                                                        itraj South Carolina
                     Typical (Upaetl
                                                                SIGNIFICANT INDUSTRIES
Are. Flow, mgd
% Industrial
BOD;, mg/1
SS, mg/1
COD, mg/l
Alkalinity, mg/1
1100 (1600)
10-11 (U.51

                Teitile chemicals

                                                                                       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
            Typical (Upset)


      -F/Mj-rbi-BODj/Ibi MLSS/day
      MCRT, days
      MLSS, mg/1
      Detention Time, hours
      Return Flow, r
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

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

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

           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

           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.

                                 MAIDEN CREEK WASTKWATER TREATMENT PLANT
                                             BLANDON, PENNSYLVANIA
   Design Flow:
   Secondary Treatment:
   0.45 aid
   Aerated Submerged Fixed
   Film (Contact Aeration)
               Population Served:
                Southeastern Pennsylvania

                    Typical (Upactj
                                                                 SIGNIFICANT INDDSTRIES
  Are. Flow, mgd
  % Industrial
  BOO;, mg/1
  SS, mg/l
  NH3, mg/1
 20 (60)
350 (900)

Food Processor
Dental Office
(1000 gpdj

Problem Polhitanta

 BOD, Flow surges
                                                  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)
                Tjrpicl (Opt)

                  450 (1,300)
                   2.8 (1.0)
                                                       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

                                Typical (Upset)

                                    15 MOO!
                                    ID (50)
                                    1 (60)
                                                                               LAND APPLICATION
                                                                               SLUOQE DRYING BEOS

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

           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
Sludge -
                                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 TREATMENT PLANT
                                           SEATTLE, WASHINGTON
 Design Flow:
 Primary Treat c
                        125 mgd
                                        Location:           Weit-Ceatral Washington
                                        Population Served:   600,000
Ave. Flow, ragd
7i Industrial
B005) mg/1
SS, rag/1
Cr, rag/I
Typical (Upet)

   0.05 'Z.OI

           Metal finishing and
                                           SIGNIFICANT INDUSTRIES

                                                                 Problem Pollutant*
                                                                                    Cd, Cr, Cu, Ni, Zn
Primary Clarif ton

  Overflow Rate, gal/f/dav
  Detention Time, hourj
  Effluent BOO?, mg/1
                                               PLANT LOADING

                                    Typical (Upset)
                                                  Digested Sludge Metal Concentration*
                                              Cadmium, mg/kg
                                              Chroiiium, rug/kg
                                              Copper, mg/kg
                                              Nickel, mg/kg
                                              Lead, nig/kg
                                                       1981  Level
19S5 Level
                                            PLANT PERFORMANCE
BOD:, m^ '1
                                                   Permit Limit    Typical (Upset)

                                                 Summer Winter  Summer  Whiter
                                                           35       110
                                                           55       '30
                                                           5.0?     <0.05



	 x 	 \



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

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  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.

                                  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)

Ave. Flow, rngd
^ Industrial
BOD$, mg/1
SS, mg/1

Typical (Upset)
165 :350)

Electroplaters, Metal
Finishers 15)
Snack Foods
(1000 gpd)

Problem Pollutants
Cd, Cr, Cu, Ni, Pb, Zn, Cn", Fe, pH
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

                   Typical  (Upet)
                    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)

                                                                                   Typical (Upcet)

BCD;, mg/I
SS. T"; ',
NH3. mg".
o 12 51151
30 30 4
3 t 1.5 (51

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

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

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.

                                    NEWARK WASTKWA-TCR TREATMENT PLANT
                                                  NEWARK, OHIO
   Design Flow:
   Secondary Treatment:
                         S.O (12.0 Hydraulic) tngd
                         Activated Sludge
              Location:           Central Ohio
              Population Served:   41,000
Ave. Flow, rogd
% Industrial
BODs, mg/l
SS,  m?/l
                    Typical (Upwt)

                                                              SIGNIFICANT INDUSTRIES

                                                                                    Problem Pollutants
(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)

                               i?4 :zso>
                               147 iZUI
                                 0 '350'

               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

AS |


                                     I     f (  DIGESTERS

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

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

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
          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.

                                NORTH SHORE SANITARY DISTRICT GORNEE PLANT
                                                GURNKZ, HJJONOE
   Dciign Flow:
   Secondary Treats
       13. mgd
       Activated Sludge
       (Two-Stage, Uodlfied-Contact}
                  PopuUtion Served:
                Northeastern Illinois
  Are. Flow, mgd
  n Industrial
  BOD;, mg/1
  SS, mg/1
  NH3, mg/1
Typical (Opsct)

      India try

Nonferrous Metal>
Military Initallation
                                                                SIGNIFICANT INDUSTRIES
(1000 gpd)

                                                                                      Problem Pollutant*
Antibiotics, SS
Cu, CN
                                                 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)


                  TfpicaJ (Dpset)

                  Typical (upacl)

                      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

                                        Typical (Dpeet)

                                           5     (17)
                                           5     (23)
                                          0.5    (15)

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


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


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.

                                             Krwwk, Kww;
   Design Flo*:
   Secondary Tr*ala*ai:
                                   Population Sra:
                                                            SIGNIFICANT DCDOSTUES
  AT*. Flow, ngd
  1 Industrial
  BOD;, mg/1
  SS, mg/1
190 (500)
Pulp tnd Ppr 
 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(nuol BOD;, mg/1
  E(llunt SS, mg/1
"tttmtti> CUriAcn
           Rait, gal/if/
  Dtotloo Tlra, houn
  SVI, ml/gtn
              Tfpicai (DpMt)

                       F/M, Ibt BOD;/1bi MLSS/daf
                       MCRT, dar
                       MLSS, m(/l
                       Detention Tin*, houri
                       Rturn Flow, %
                       D.O. Lartl, m|/l
                          , mf/1
                     PLANT PXJtrORMANCS

                             Pwmit Llailt

                                  Typical (0*Ml)

                                      i5 1401
                                      Z5 (601

                                                                              .  OCEAN

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

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.

                                      SIOOX CITY WASTT TREATMENT PLANT
                                                3OU* CITY, IOWA
   Design Flow:
   Secondary Treatment:
                  Population Served:
                Northwest Iowa
                                                                SIGNIFICANT INDUSTRIES
  Ae. Flow, mgd
  % Industrial
  BOD;, mg/1
  SS, mg/1
Typical (Cp*eO

   380 (6U)
   550 (630)
Meat Processing
Metal Finishing
Flo write

         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 (Dpet)             Aeration Baaina
                     220 (3701
                     240 (2351
                  Typical CUp*et)

                        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)
                       BOD;, mg/1
                       SS, mg/l
                                              PLANT PERFORMANCE

                                                      Permit Limit
                                    Typical (Upset)

                                        34 '371
                                        33 [45i
                                                                            LUOQE LAGOON*

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
          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

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.

                                   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

Ave. Flo*, mgd
% Industrial
BOD,, mg/1
SS, mg/1
                                APPENDIX B

                        INTERFERING SUBSTANCES

     Biochemical Oxygen Demand
     Fats, Oil and Grease




     Chlorophenoxy Herbicides
Suspended Solids
Organometallic Pesticides


      Carbon Tetrachloride                       Methylene Chloride
      Chloroform                                Tetrachlorodibenzodioxins
      Chloromethane                            Tetrachlorodibenzofurans
      Dichloroethane                            Tetrachloroethane
      Dichloroethylene                           Tetrachloroethylene
      Dichloropropane                           Trichloroethane
      Hexachlorobutadiene                       Trichloroethylene
      Hexachlorocyclohexane                     Vinyl Chloride


      Acetanilide                                Dyes
      Acetonitrile                               EDTA
      Acrylonitrile                              Ethylpyridine
      Aniline                                    Fluorenamine
      Benzidine                                 Hydrazine
      Benzonitrile                               Nitrosodiphenylamine
      Chloroaniline                              Pyridine
      Dichlorobenzidine                          Trisodium Nitrilotriacetate
      Dimethylnitrosamine                       Urea

OXYGENATED COMPOUNDS   (Acids,  Alcohols,  Aldehydes,  Esters,  Ethers,

      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

              Catechol                                  Pentachlorophenol
              Chlorophenol                              Phenol
              Cresol                                    Trichlorophenol
              Dichlorophenol                            Trinitrophenol
              Dinitrophenol                             Vanillin


              E thylhe xylphthalat e


              Anthracene                               Naphthalene
              Benzo (a)  Anthracene                      Phenanthrene
              Chloronaphthalenes                        Pyrene
t> U.S. flOVERNMENT PfWnTNG OFFICE: 17- 7 1 6- 0 0 2i  60699