United States
Environmental Protection
Agency
Industrial Environmental
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-152 Nov 1984
SEPA Project Summary
Field Manual—Performance
Evaluation and Troubleshooting
at Metal-Finishing Wastewater
Treatment Facilities
T. N. Sargent, G. C. Patrick, and E. H. Snider
The main purpose of this technical
field manual is to provide a trouble-
shooting reference document for iden-
tifying, analyzing, and solving prob-
lems encountered during the operation
of waste treatment equipment in
metal-finishing facilities. It is also
meant to assist owners and operators
in improving the performance and effi-
ciency of treating metal-finishing pro-
cess wastes from these facilities. The
manual describes general procedures
for evaluating treatment processes and
equipment commonly used in this in-
dustry, as well as other items related
to the effective operation of treatment
facilities.
The methodology used to evaluate
compliance problems and to develop
operation and maintenance (O&M) spe-
cifics is described in a review of the lit-
erature, followed by an assessment of
the causes of permit violations and the
recommended measures for improving
compliance.
The unit processes described in this
manual are those generally used in
treating metal-finishing wastes. These
procedures are: equalization, oil re-
moval, cyanide oxidation, chromium
reduction, pH control, metal precipita-
tion, flocculation, sedimentation, filtra-
tion, gravity thickening, belt filter press-
es, vacuum filtration, pressure filtration
for dewatering, and centrifugation. For
each of these unit processes, the man-
ual contains information on theory of
operation, description of equipment,
operational procedures, typical perfor-
mance values, and a troubleshooting
guide.
This Project Summary was de-
veloped by EPA's Industrial Environ-
mental Research Laboratory, Cincin-
nati, OH, to announce key findings of
the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Plant personnel responsible for waste
treatment processes and for achieving
permit compliance must be knowl-
edgeable, not only about the problem
area, but also about the electroplating
and related metal-finishing concepts,
and in-plant process modifications and
changes as they relate to the waste
treatment processes. Troubleshooting
guides, operating strategies, and pro-
cess monitoring material are discussed
in detail for each unit process com-
monly used in metal-finishing waste
treatment.
It is assumed that the manual user
has a general understanding of treat-
ment facilities and their operation. The
style, language, and format are directed
to the level and technical knowledge of
a technician having some experience
with in-plant operation, design, inspec-
tion, and performance evaluation.
Procedure
A literature review was conducted
utilizing technical publications, govern-
ment reports and documents, and a
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computerized literature search. The lit-
erature search also included equipment
manufacturers' information, data pro-
vided by professional organizations,
and communications with personnel
who were familiar with the treatment
and disposal of metal-finishing wastes.
The objectives of the literature review
were to collect data that would aid in
identifying the major causes of permit
violations, and to collect information
that could be used to develop O&M spe-
cifics on the treatment and disposal of
metal-finishing wastes. Furthermore,
by qualifying these data and informa-
tion, methods and techniques for im-
proving compliance of facilities could
be developed.
Analysis of Permit Violations
Permit violations were analyzed to
understand the problems associated
with treatment of metal finishing
wastes. The troubleshooting manual
was then prepared to address the prob-
lems. An analysis of permit violations
was performed utilizing the Quarterly
Noncompliance Report published by
the Office of Water of the U. S. Environ-
mental Protection Agency (EPA). The
report listed the major industries and
parameters that were out of com-
pliance. The violations in the Non-
compliance Report were listed by SIC
code. The SIC numbers used for iden-
tifying industries with metal wastes
were 3471 (electroplating), 3631, 3632,
3633, 3639, 3714, 3721, and 3731.
The report cited 34 industries that
were out of compliance from the third
quarter of 1979 to the second quarter
1982. The 10 parameters that were most
frequently out of compliance between
1979 and 1982 are listed below:
Number of Permit
Violation
Parameter
Nickel
Cyanide
Chromium
pH
Copper
Phenol
TSS
Cadmium
Zinc
Lead
Occurrences
17
16
15
12
11
8
7
6
6
4
This field manual addresses all the
parameters listed except phenol. Treat-
ment for removal of phenol was not in-
cluded because it is not specifically reg-
ulated in the effluent guidelines for the
electroplating industry. Treatment prac-
tices for control of the other nine
parameters, as well as oil and grease,
are included in the manual.
Operation and Maintenance
Specifics
O&M specifics for the treatment of
metal-finishing wastes were obtained
from a search of technical publications,
a computerized literature search, and
contacts with equipment manufacturers
and operators. The information col-
lected from these sources was then in-
terpreted, compiled, and developed
into this field manual.
Computerized Literature Search
A computerized literature search was
performed using DIALOG information
Service* of Lockheed Corporation. The
computerized literature review was
conducted in three steps. The first step
was to locate the abstracts from the
various data base files. The second step
was to search the abstracts for the ap-
propriate publications and documents.
The final step was to review the publica-
tions.
The first step was selecting the key-
words or series of keywords used to de-
scribe O&M specifics for metal-finish-
ing waste treatment. A series of
keywords coupled by the words "and"
or "or" is often used to select the de-
sired abstract. A question mark in a
keyword indicates that the identity of a
letter is unknown and the computer is
to identify all references including the
letters that precede the question mark.
For example, the keyword "chrom?"
will cause the computer to search re-
cords labeled chrome, chromium, chro-
mate, etc. The series of keywords selected
are listed below.
1. NPDES or Permit and (Violation or
Exceed) and Metal.
2. Wastewater and Operation? and
Maintenance.
3. Operation and Maintenance and
Metal?
4. Metal? and Precipitate? and Waste-
water?
5. Cyanide? and (Oxidation or Re-
moval or Treatment) and Waste-
water.
6. Chrom? and (Reduction or Re-
moval or Treatment) and Waste-
water.
•Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use.
The keywords were then used t
search the 37 data files in Lockheed'
DIALINDEX. The search of the data files
revealed the number of abstracts that
contained the keywords. The informa-
tion was used to ensure that the
keyword series was restrictive enough
without being overly restrictive. The
two files that contained the most
abstracts applicable to this project were
the Metals Index (File 32) and the Pollu-
tion Abstracts Index (File 41). The Met-
als Index contained 99 abstracts that
could be identified by the six series of
keywords described above. The Pollu-
tion Abstracts contained 445 abstracts.
The second step was reviewing the
abstracts identified by the keywords for
both the metals data file and the pollu-
tion data file. These abstracts were re-
viewed to see which publications were
most applicable to the project.
The final step was reviewing and
evaluating the article chosen from the
abstract search and incorporating this
information into the O&M manual.
Much of the information was used to
review current treatment practices and
to develop O&M specifics for the trou-
bleshooting manual. These articles
were only referenced when they con-
tained specific information such as sur-
face loading rates or mixing horse-
power.
Technical Publications
The review of literature included tech-
nical publications that were not in-
cluded in the computerized data base
or those publications that were more
easily obtained by a manual literature
search. The former category contained
articles that were published generally
before 1970 and contained many refer-
ence books. The search of articles be-
fore 1970 was performed by reviewing
annual indexes from publications such
as Proceedings of the Purdue University
Industrial Waste Conference, Journal
Water Pollution Control Federation, and
Water and Waste Engineering.
Sources from which information and
data on metal-finishing waste treatment
could be easily obtained were the EPA,
the Water Pollution Control Federation
(WPCF), the American Electroplating
Society (AES), and reference books.
More than 40 EPA publications relating
to metal-finishing wastes were re-
viewed. A series of seven EPA Technol-
ogy Transfer documents provided
much general information about metal-
finishing waste treatment. Twelve AES^
project reports were also reviewed.fl
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Numerous reference books on treat-
ment of metal wastes were also iden-
tified and reviewed. This review in-
cluded books written for treatment of
metal-finishing wastes, and materials
that described pH control, sedimenta-
tion, and sludge dewatering.
Equipment Manufacturers
Several manufacturers of equipment
for metal-finishing wastes were con-
tacted. Information obtained from man-
ufacturers' representatives was used to
characterize and describe the different
types of equipment, to develop O&M
specifics, and to obtain performance
data. This information on field O&M
was referenced when used.
Results and Discussion
Conventional Wastewater
Treatment
Conventional wastewater treatment
in the electroplating industry consists of
the following unit processes (see Figure
1):
• Chromium reduction (if needed)
of segregated chromium waste
streams to reduce the chromium
from its hexavalent form to the tri-
valent state, which then can be pre-
cipitated as chromium hydroxide
by alkali neutralization,
• cyanide oxidation (if needed) of
segregated cyanide-bearing waste
streams to oxidize the toxic cya-
nides to harmless carbon and nitro-
gen compounds,
• neutralization of the combined
metal-bearing wastewaters, acid/
alkali wastewaters, strong chemi-
cal dumps, and the effluent from
the cyanide and chromium treat-
ment systems to adjust the pH
within acceptable discharge limits
and to precipitate the dissolved
heavy metals as metal hydroxides,
• clarification, in which flocculating/
coagulating chemicals are added to
promote the initial settling of the
precipitated metal hydroxides, and
• gravity thickening over extended
time to increase solids content of
sludge before disposal.
These unit processes provide effec-
tive, reliable treatment for many elec-
troplating waste streams. This is not to
say, however, that such treatment is
suitable for all applications or that the
"normal" design parameters (retention
time, reagent dosage, and so forth) will
provide effective pollutant removal
Chrome Waste
Acid'
SO
Wastewater
Discharge
Cyanide
' Oxidation
Legend:
S - sulfonator
C = chlorinator
ORP = oxidation reduction potential
Thickening
Solid Waste}
Disposal
Figure 1. Electroplating industry conventional wastewater treatment.
from every individual plater's wastewa-
ter discharge.
Many of the items covered in this
manual have their basis in a conven-
tional wastewater treatment system
such as the one described above.
Problem Assessment
A plant assessment is the initial step
in a pollution control program and it in-
volves a thorough analysis of the opera-
tions of a metal-finishing plant that re-
late to pollutant sources and water use.
The information is used in evaluating
the application of in-plant changes for
reducing chemical loss and water use.
A plant assessment includes the follow-
ing steps: (1) inspect plating room lay-
out, (2) review plant operation prac-
tices, (3) examine process water use, (4)
perform sampling and laboratory anal-
ysis to characterize waste streams and
to determine dragout rates, and (5)
identify the frequency, volume, and
characteristics of batch dumps.
Laboratory analyses of wastewater
samples are performed using standard
EPA-approved techniques. Throughout
the manual, various analytical param-
eters and their concentrations are dis-
cussed. For all tests the analytical
methodology presented in the EPA doc-
ument, "Methods for Chemical Analysis
of Water and Wastes" or "Standard
Methods for the Examination of Water
and Wastewater" should be followed.
The successful O&M of a waste treat-
ment plant requires consistent perfor-
mance that exceeds regulatory com-
pliance levels. Failure to meet these
compliance levels can result in costly
disposal alternatives, fines, damage to
the environment, and adverse public re-
action. If a treatment facility fails to
meet compliance standards, the prob-
lem usually can be attributed to one of
the following causes:
1. shock loadings (hydraulic or con-
taminants) to the waste treatment
plant,
2. poor understanding of O&M pro-
cedures,
3. poor process control,
4. equipment failure, and
5. treatment plant design inadequa-
cies.
The potential effect of good O&M on
each of the five categories of non-
compliance reasons is discussed below.
If a plant is out of compliance, it should
be determined which categories of
causes are applicable and appropriate
action should be taken to see if im-
proved O&M procedures could affect
performance.
Shock Loadings
Frequently, noncompliancecan result
when shock loadings of flow or contam-
inants cause treatment process upsets.
Sources of these shock loadings can be
either spills or releases from production
batch operations or cleaning opera-
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tions. Their impact on the treatment
process can be mitigated by installing
sufficient equalization. Often their effect
can also be controlled by changes in
operating procedures in the production
facility or in the treatment plant. Of
foremost importance is communication
between production and waste-treat-
ment personnel. If waste treatment per-
sonnel are notified of potential shock
loads in sufficient time, mitigating ac-
tion often can be taken, such as divert-
ing the shock load to sidestream equali-
zation to temporarily bypass sensitive
processes or to manually modify pro-
cess operating parameters to adjust for
the shock loading.
Modifying spill control and operating
procedures for batch processes and
cleaning operations can reduce the
magnitude of shock loadings in several
ways: wastes from batch or cleaning
operations can be released slowly dur-
ing times of low flow; spills can be
cleaned up using dry chemicals, rather
than down the drain; and chemical
handling procedures can be modified to
reduce the likelihood of spills and
chemicals can be stored in diked areas
to contain spills that do occur.
In all cases, implementation of the
above procedures requires training of
all personnel in proper operating proce-
dures to control or mitigate shock load-
ings. Part of this training must include
making production personnel aware
that their procedures affect waste treat-
ment. This factor is becoming increas-
ingly important as some facilities have
had to curtail production in order to
achieve discharge compliance levels.
This action may be diverting flow to
sidestream equalization, bypassing an
oil water separator while a non-oily
hydraulic shock load is occurring,
notifying production to stop or slow an
excessive discharge, or other appropri-
ate procedures.
Poor Understanding of
O&M Procedures
Understanding O&M procedures is
essential to successfully operate a
metal-finishing wastes treatment facil-
ity. An operator who is well versed in
the proper O&M procedures can usually
operate the treatment facility to meet
permit compliance, even though one or
more of the above causes of permit vio-
lation exists at the treatment facility.
This manual was developed to assist
operators in implementing the proper
O&M procedures at the treatment facil-
ity. While no manual can be general
enough for all plants and yet specific
enough for one plant, the intention of
this manual is to aid in understanding
the cause/effect relationship for several
treatment processes. Once an operator
has developed a cause/effect relation-
ship for the control variables at the
treatment facility, specific adjustments
and/or set-points can be established. A
successful O&M program enables un-
derstanding the cause of the problem
and what effect it will have on com-
pliance, and then adjusting the control
variables so as to mitigate the problem.
Poor Process Control
One of the most common causes of
continuous poor performance and fre-
quent noncompliance is poor process
control, which results in the treatment
plant not achieving its full capacity and
efficiency. When the full or design effi-
ciency is not achieved, the blame is put
frequently on poor design, but it must
be remembered that the design is
based upon the assumption of good
process control, which may or may not
be occurring. Process control can only
be achieved by well-trained operators
who understand their equipment and
the purpose of all operating variables
under their control. This includes un-
derstanding the interaction between
operating variables and the trade-offs
often involved. As an example, increas-
ing the belt tension in a belt filter press
can result in a drier cake, more solids in
the filtrate, and a shorter belt life. How-
ever, the solids in the filtrate might ad-
versely affect the performance of other
treatment processes, such as an oil
coalescer.
Process control through good opera-
tions is particularly important in the
metal-finishing industry where several
waste treatment processes require criti-
cal control of operating variables to
achieve good treatment peformance.
Examples include pH control for metal
precipitation and pH and oxidation-re-
duction potential (ORP) control for
chromium reduction and cyanide oxida-
tion. A relatively slight change in these
operating variables can result in signifi-
cant degradation in performance, non-
compliance, and in the case of cyanide
reduction, the potential for release of
toxic gases.
Equipment Failure
Equipment failure can readily cause a
treatment plant to fail to meet regula-
tory compliance levels. The effect of the
equipment failure can be minimal when
repairs are implemented quickly or the
effect may be major, since parts and re-
pairs may take days to obtain and in-
stall. Therefore, it is essential to mini-
mize equipment failure and downtime.
Minimizing downtime can be achieved
partially by a sufficient parts inventory
and overdesign; it also requires proper
O&M of existing treatment plant equip-
ment. Mechanical equipment has a set
of design operating conditions, and
anytime these conditions are exceeded,
premature equipment failure can occur.
Treatment plant personnel should be
aware of these design conditions and
integrate them with plant operating
procedures to ensure that mechanical
equipment is not unduly stressed. It
should be noted that this stress does
not always come from mechanical
forces. Improper pH levels can corrode
equipment and excessively high tem-
peratures can cause construction mate-
rials to fail. Once equipment failure has
occurred, prompt repair of equipment
by well-trained maintenance personnel
is essential to minimize the effect and
prevent recurrence. A regular and or-
derly inspection of equipment for wear
or other early signs of trouble, such as
vibration, can also prevent premature
equipment failure.
Treatment Plant Design
Inadequacies
No amount of proper O&M can make
an incorrect or improperly designed
treatment plant achieve consistent
compliance with regulatory standards;
conversely, inadequate O&M practices
can render even the best designed
treatment plant incompliant. Before any
major design modifications are imple-
mented, the potential for treatment plant
performance improvement through im-
proved O&M should be investigated
thoroughly.
Conclusions
This manual details performance
evaluation of wastewater treatment fa-
cilities for metal-finishing wastes. Trou-
bleshooting guides on unit process op-
erations are included to help pinpoint
causes of treatment malfunctions.
It is concluded that operators and
owners of metal-finishing plants can
use this manual to help bring their
wastewater treatment facilities into
compliance. This can be accomplished
best by a joint effort on the part of man-
agement and the operators.
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Monitoring of treatment parameters
is the key factor in determining perfor-
mance of facilities and an early warning
for non-compliance trends.
Recommendations
Improving Permit Compliance
The level of pollutants discharged to
publicly owned treatment works by
plants following pretreatment must
meet new regulations. The electroplat-
ing and metal-finishing point source
categories is regulated by the EPA (Fed-
eral Register, 48(137), 32462-32488J
July 15, 1983).
Improving the level of permit com-
pliance for treatment of metal-finishing
wastes is a two-step process. The first
step is to identify the problem and the
second step is to take the necessary cor-
rective actions. Permit compliance
problems are generally in the following
four categories: 1) design, 2) operation,
3) administration, and 4) maintenance.
The importance of proper design can-
not be overstated. Each unit process
along with the integrated waste treat-
ment system must be designed with
numerous factors accounted for. An im-
properly designed plan seldom oper-
ates well. Design improvement to en-
hance permit compliance is a long-term
process; near-term improvements are
seldom attainable through design
changes.
Performance of a well-designed sys-
tem may be affected by improper oper-
ating procedures. Thus, an operator's
familiarity with correct O&M procedure
can directly improve operation of a sys-
tem. It is the goal of this publication to
provide adequate O&M procedures and
troubleshooting guides to produce im-
proved levels of permit compliance in
metal-finishing waste treatment plants.
Administration affects permit compli-
ance, although often in an indirect man-
ner. Such items as staff supervision,
motivation, funding, and planning af-
fect the operation of a facility, which, in
turn, affects all aspects of the treatment
plant.
Finally, maintenance affects permit
compliance directly. In numerous in-
stances throughout the descriptions
that follow, routine inspection and
maintenance are cited as the chief de-
terrents to operating problems, and
hence to permit violations. A compe-
tent, well-trained maintenance group is
indispensable in the smooth and suc-
cessful operation of a treatment plant.
Although the tendency is to categor-
ize permit compliance problems as be-
longing strictly to one of the four areas
discussed above, the fact is that most
problems have aspects of two or more
areas. Plants owners and operators that
hope to improve permit compliance
must strive to achieve improvement in
all four categories.
Resource Recovery
Recommendations
Pollution control legislation has af-
fected industry by increasing the eco-
nomic penalty associated with ineffi-
cient use of resources. In the plating in-
dustry, for example, loss of a raw mate-
rial in the wastewater can result in three
distinct cost items: replacement of the
material, removal of the material from
the wastewater before discharge, and
disposal of the residue. Similar cost
items exist for process water: replace-
ment of water (no longer inexpensive
to purchase) used in processing, pro-
cessing the water in the wastewater
treatment system, and processing the
water by the treatment plant after dis-
charge into a public sewer system.
In response to the increased cost of
raw material losses, plating shop pro-
cesses are being modified to reduce
these losses as well as water consump-
tion. Recent years also have seen the
cost-effective application of various
separation processes that reclaim plat-
ing chemicals from rinse waters, en-
abling both the raw material and the
water to be reused.
The impact of resource recovery and
pollutant load reduction modifications
on waste treatment and solid waste dis-
posal costs must be measured, if these
modifications are to be evaluated. Cost
of sophisticated treatment necessary
for electroplating wastewater and of
residue disposal often provides a signif-
icant economic incentive for resource
recovery.
Reduced Loading
Recommendations
Modifications that will reduce the pol-
lutants or wastewater loadings on a
treatment facility range from using flow
restrictors to eliminate excess dilution
in rinse tanks to installing recovery
units, such as reverse osmosis and
evaporation, to separating plating
chemicals from rinse water for recycle
to the plating bath. Actions that can
minimize wastewater volume include
the following:
• implementing rigorous housekeep-
ing practices to locate and repair
water leaks quickly,
• employing multiple counterflow
rinse tanks to reduce rinse water
use substantially,
• employing spray rinses to mini-
mize rinse water use,
• using conductivity cells to avoid
excess dilution in the rinse tanks,
• installing flow regulators to mini-
mize water use, and
• reusing contaminated rinse water
and treated wastewater where
feasible.
Steps to minimize pollutant loadings in-
clude:
• implementing a rigorous house-
keeping program to locate and re-
pair leaks around process baths, re-
placing faulty insulation or plating
racks to prevent excessive solution
drag-out, installing drip trays
where needed, etc.
• using spray rinses or air knives to
minimize solution drag-out from
plating baths,
• recycling rinse waters to plating
bath to compensate for surface
evaporation losses,
• using spent process solutions as
wastewater treatment reagents
(acid and alkaline cleaning baths
are obvious examples),
• using minimum process bath
chemical concentrations,
• installing recovery processes to re-
claim plating chemicals from rinse
waters for recycle to the plating
bath, and
• using process bath purification to
control the level of impurities and
prolong the bath's service life.
Closed-loop chemical recovery from
a rinse stream can often provide the sol-
ution to treat. Applying a closed-loop
recovery system to a plating operation
eliminates the need to treat the rinse
water normally associated with that
step.
In the case of rinse streams requiring
pretreatment (for example, cyanide or
chromium) or rinses containing pollut-
ants not effectively removed by conven-
tional end-of-pipe technology (for
example, some types of complexed
metals), installing a closed-loop system
to recycle the rinse may reduce the in-
vestment needed to comply with the
effluent quality limitations.
i USGPO: 1984 — 559-111/10725
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T N. Sargent, G. C. Patrick, and E. H. Snider are with Engineering-Science,
Inc., Atlanta, GA 30329.
T. J. Powers is the EPA Project Officer (see below).
The complete report, entitled "Field Manual—Performance Evaluation and
Troubleshooting at Metal-Finishing Wastewater Treatment Facilities," (Order
No. PB 85-107 274; Cost: $23.50, subject to change) will be available only
from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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