United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/056 Jan 1988
Project Summary
Waste Minimization Audit
Report: Case Studies of
Minimization of Cyanide
Waste from Electroplating
Operations
To promote waste mirrifnization
activities in accordance with the national
policy objectives established under the
1984 Hazardous and Solid- Waste
Amendments to the Resource Conser-
vatism and Recovery Act of 1976
(RCRA), the Hazardous Waste Engi-
neering Research Laboratory (HWERL)
of the USEPA Office of Research and
Development has undertaken a project
to develop and test a waste minimiza-
tion (WM) audit procedure.
As part of this project, a total of 6
WM audits were carried out in four
separate facilities. This report presents
the results of the on-site WM audits
performed at two electroplating facilities
that generate cyanide-beating, wastes.
Thar report also describes the WM audit
procedure as it has-developed from the
initial (pre-project) sequence of steps,
to the modified (post-project) sequence
that reflects the1 experience gained dur-
ing this HWERL project.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, 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
To promote waste minimization activi-
ties in accordance with the national policy
objectives established under the 1984
Hazardous and Solid Waste Amendments
to the Resource Conservation and Re-
covery Act of 1976 (RCRA), the Hazardous
Waste Engineering Research Laboratory
(H.WERL)>of theUSEPA Olfic&af Research
and Development has undertaken a pro-
ject ta dtevetop and test a waste mini-
mization (WM) audit procedure.
As part of this project, a total of 6 WM
audits were carried out in four separate
facilities. The full report presents the
results of the on-site WM audits per-
formed at two electroplating facilities that
generate cyanide-bearing wastes. The
report also describes the WM audit proce-
dure as it has developed from the initial
(pre-project) sequence of steps, to the
modified (post-project) sequence that
reflects the experience gained during this
project. The 4 other audits, 2 dealing
with solvent wastes and 2 dealing with
heavy metal and corrosives wastes, are
discussed in two separate reports.
Waste Minimization
Audit Procedure
The main objective of the full report is
to provide useful guidelines for the con-
duct of a WM audit. The following sections
discuss how a WM audit fits into an
overall WM program, and provide brief
descriptions of the principal elements of
a WM audit.
The Role of the WM Audit
In a WM Program
The primary objective of a waste mini-
mization program is to reduce the quantity
and/or toxicity of waste effluents leaving
the production process. The essential
elements of a WM program include the
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initiation and planning of the program,
the planning and execution of a WM
audit, and the implementation of the
recommended measures that emerge from
the audit process.
During the program initiation phase,
the commitment of top management to
reduce waste generation must be estab-
lished, which results in the development
of an organizational structure for the WM
program and in the setting of waste
reduction goals for the entire organization.
The next step involves characterization of
waste generation rates and waste char-
acteristics. The program planning step
follows, with the selection of the audit
team(s) to carry out the actual auditing
phase. The auditing process constitutes
the most important element of the overall
WM program, since it provides the key
inputs for the generation of WM options,
as well as for the decisions of which
waste minimization measures should be
implemented. Following the audit, selec-
tion of options for implementation are
made based on feasibility analysis. Finally
WM measures go through the sequence
of design, procurement, construction,
startup, and performance monitoring.
Waste Minimization
Audit Procedure
The execution of a waste minimization
audit can be divided into three distinct
phases, as shown in Table 1. The overall
objective of the pre-audit phase is to
gather and analyze the information
necessary to select a waste stream(s) for
the facility audit. The audit phase follows,
the objective of which is to develop a
comprehensive set of WM options and to
screen them. The product of the audit
phase is a list of options selected for
further evaluation. A technical and
economic feasibility analysis is performed
for each selected option during the post-
audit phase of the program. This phase
ends with the preparation of a final report.
The following paragraphs provide a brief
description of each audit step.
1. Preparation for the audit
The objective of this step is to gain
background information about the facility
to be audited. Preparation should include
examination of information sources re-
lated to the processes, operations, and
waste management practices at the
facility. The result of proper preparation
should be a well-defined needs list, in-
spection agenda, or a checklist detailing
what is to be accomplished, what ques-
tions or issues need to be resolved, and
what information needs to be gathered.
The needs list should be provided to the
facility before the actual site visit to allow
the facility personnel to assemble the
materials needed by the audit team in
advance.
2. Pre-audit meeting
The next step is a pre-audit meeting
with plant personnel. This initial contact
should include solicitation of plant per-
sonnels' views on the focus and function
of the audit. The information needs
identified in the previous step should be
discussed. A tour of the facility should be
performed to familiarize the audit team
with the operations performed. During
this meeting, it is important to establish a
key facility contact.
3. Data compilation and waste
stream selection
Selecting the principal waste streams
or waste producing operations for the
audit provides the audit team with the
focus for the effort. The criteria used for
waste stream selection include waste
composition, quantities, degree of hazard,
method and cost of disposal, perceived
potential for minimization, and compliance
status.
After all pertinent data are collected,
they should be assembled in the form of
a written facility description. The descrip-
tion should include facility location and
size, description of pertinent operations
or processes, and a description of the
waste streams centering on sources,
generation rates, and current methods of
management. The report should include
a written justification for selection of a
waste stream(s) for study.
4. Audit inspection
The audit inspection is the ultimate
step in the information gathering process.
The governing objective of this step is to
evolve a fuller understanding of primary
and secondary causes of waste generation
for the selected waste streams, and to
cover the items missed in the pre-audit
phase. The audit inspection must result
in a clear understanding of waste gen-
eration causes. Useful guidelines for this
step include having a detailed inspection
agenda ready in advance, scheduling the
Table 1. Recommended Waste Minimization Audit Procedure
Activities
Program
Phase
Product
Pre-Audit 1. Preparation for the audit
2. Pre-audit meeting and inspection
3. Data compilation and waste
stream selection
Audit 4. Facility inspection
5. Generation of a comprehensive
set of WM options
6. Options evaluation
7. Selection of options for feasibility
analyses
Post-Audit 8. Technical and economic feasibility
analysis
9. Final report preparation
• needs list/inspection agenda
• nofes
• facility and process description
• waste description
• rationale for selection
• notes
• list of proposed options with
written rationale
• independent options ratings by audit
team and by plant personnel
followed by joint review
• list of selected options
• options interim report
study or budget grade estimates of
capital and operating costs;
profitability analysis
' final report with recommendations
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inspection to coincide with the particular
operation that is of interest, obtaining
permission to interview plant personnel
directly, obtaining permission to photo-
graph the facility, observing the "house-
keeping" aspects of operation, and
assessing the level of coordination of
environmental activities between various
departments.
5. Generation of WM options
The objective of this step is to generate
a comprehensive set of WM options. It is
important at this point to list as large a
number of options as possible, including
WM measures currently in place in the
audited facility. Option generation should
follow a hierarchy to reflect the environ-
mental desirability of source reduction
over recycling, and of recycling over
treatment. Options can be generated by
examining the technical literature,
through discussion with manufacturers
of equipment or suppliers of process input
materials, and through the use of a
checklist. Table 2 provides a checklist
suitable for electroplating wastes.
6. Options evaluation
Each of the options postulated in the
preceding step must undergo a pre-
liminary qualitative evaluation. The ob-
jective of this evaluation is to weed out
the measures that do not merit additional
consideration and to rank the remaining
measures in the order of their overall
desirability. The evaluation should con-
sider aspects such as waste reduction
effectiveness, extent of current use in the
facility, industrial precedent, technical
soundness, cost, effect on product quality,
effect on plant operations, implementation
period, and implementation resources
availability. It is recommended that the
evaluation process be performed indepen-
dently by both the audit team and the
host facility personnel. A rating system
has been developed to rank the measures
in a consistent pattern and to provide a
framework for resolving the differences
in opinions.
7. Selection of options for
feasibility analysis
Following the evaluation process by
the two independent groups, the two sets
of ratings are compared and discussed in
a joint meeting in order to develop ratings
which are mutually acceptable. The pro-
duct of this meeting is a WM options list
with revised ratings. The final ratings are
then used as a basis for the selection of
options for additional feasibility analysis.
The number of measures promoted to the
Table 2. Source Reduction Options Checklist for Cyanide Wastes from Electroplating Operations
Options Comments
Drag-out minimization
Workplace positioning
Withdrawal speed and drainage
Drag-out recovery
Concentration
Temperature
Surfactants
Extension of bath life
Drag-in reduction
Deionized water
Impurity removal
Rack maintenance
Anodes
Return solution
Minimization of rinse water
Automatic flow control
Agitation
Multiple tanks
Spray/fog nozzles
Closed-loop rinsing
Non-cyanide solutions
Copper plating
Cadmium plating
Silver stripping
Alternate plating techniques
Ion vapor deposition
Good operating practices
Segregation
Training/supervision
Spill and leak prevention
Maintenance
Material tracking/control
— By reducing drag-out, less of the plating solution leaves the tank.
— Proper positioning of the part of the rack reduces solution drag-out.
— Slow speeds reduce drag-out. Parts should be allowed to drain over tank.
— Drain boards and drip tanks can be used to recover plating solutions.
— Reducing the concentration of the bath reduces losses due to drag-out.
— Increased temperature reduces solution viscosity/surf ace tension.
— Lower the surface tension of the solution which reduces drag-out.
— Reduces the frequency of spent bath replacement.
— Efficient rinsing prevents cross-contamination of solutions.
— Reduces the build-up of calcium and magnesium ions in the bath.
— Can be performed by chemical precipitation, freezing (carbonates), or by filtering (particulates).
— Corrosion and salt deposits on the rack can contaminate plating baths.
— Use of purer anodes and bags will prevent insoluble impurities in the anodes from entering the bath.
Anodes should be removed when not in use.
— Some manufacturers of plating solutions will reprocess spent baths.
— Reducing flow promotes recovery of metals and makes treatment more effective.
— Reduces water use while insuring required degree of rinsing.
— Increases rinsing efficiency which reduces the volume of water needed.
— Counter-current rinsing can reduce water requirements by 60 to 90 percent.
— More efficient than rinsing a part in a tank of water.
— Susceptable to impurity build-up and may require the use of a recovery system, e.g., evaporation, ion
exchange, reverse osmosis, electrodialysis.
— Eliminates the generation of a cyanide-bearing waste.
— Pyrophosphate copper plating solution may be used as a replacement.
— Substitutes include cadmium fluoborate and acid sulfate cadmium baths.
— May be performed with potassium nitrate and ammonium hydroxide.
— Eliminates the use of hazardous plating solutions.
— Can be used to plate parts with cadmium or aluminum. Required equipment is very complex and
expensive.
— Helps to minimize waste generation through procedural policies.
— Proper segregation can prevent mixing of hazardous and non-hazardous waste.
— Operator awareness can help identify and eliminate wasteful practices.
— Reduces the loss of materials and the generation of clean-up wastes.
— Preventive and corrective maintenance reduces spills, leaks, and upsets.
— Provides the facility with accurate material balances which can be used to identify and quantify material
and waste handling problems.
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feasibility evaluation stage depends on
the time, budget, and resources available
for such study.
8. Analysis of technical and
economic feasibility
The specific WM options selected for
additional evaluation must be analyzed.
Study-grade (e.g., ±30% accuracy) esti-
mates for the capital and operating costs
can be obtained from preliminary vendor
information or factored estimation tech-
niques. Once the costs are obtained, the
analysis is focused on an estimation of
profitability, based on conventional
methods (payback period, internal rate of
return, or net present value).
9. Final report preparation
As the concluding step of a WM audit,
a final report should be prepared to
summarize all the pertinent data, results,
and recommendations.
Results of Waste Minimization
Audits for Cyanide Wastes
Waste minimization audits were con-
ducted at two electroplating facilities
generating cyanide-bearing wastes. The
following sections summarize the reports
prepared for each facility.
Facility C-1A/B
Facility C-1A/B, located in Southern
California, is a major aviation, industrial,
and seaport complex supporting anti-
submarine aircraft, helicopters, and air-
craft carriers of the Pacific Fleet. Cyanide
wastes are generated from various oper-
ations associated with the plating shop.
The principal metals plated at this facility
are chromium, nickel, aluminum, copper,
cadmium, and silver.
Plating is performed using racks or
barrels. The sequence of unit operations
is very similar for the plating of different
type of metals and includes alkaline
cleaning, acid cleaning, stripping (if the
removal of old coating is required), and
electroplating. Each operation is followed
by a single flowing water rinse.
The cyanide loss and subsequent waste
stream generation is due to (a) drag-out
of plating/stripping solutions, which
enter the rinse water, and (b) plating
solution filtrate, which is retained in the
filtering medium and disposed of as solid
waste. Owing to a high drag-out rate, the
solutions are replenished frequently and
do not have to be replaced periodically.
Out of 650,000 gallons of wastewater
generated daily, about 5 percent is esti-
mated to originate from cyanide-based
plating operations.
A total of 31 source reduction options
were considered and grouped into six
distinct categories based on the similarity
in end-result of the methods. The cate-
gories include drag-out minimization, bath
life extension, rinse water minimization,
substitution of non-cyanide solutions,
substitution of alternate plating metals or
techniques, and good operating practices.
Each measure was then rated based on a
pre-established rating system.
Through a joint review of the ratings of
each proposed waste minimization option
by the audit team and facility personnel,
a set of high-ranking options was selectee
for additional evaluation and analysis
The options chosen as candidates for
further analysis were reduction of drag-
out using drain boards and extension o1
bath life through impurity removal, re-
duction of drag-out using drain boards
and extension of bath life through con-
version to mechanical agitation, recovery
of drag-out using still rinsing, reduction
of water usage using spray rinsing, and
substitution of non-cyanide cadmium
plating solutions. Table 3 summarizes the
results obtained from the economic
feasibility study associated with these
options.
A preliminary economic feasibility study
was independently performed for 5 waste
minimization options selected from among
31 options initially considered. Since the
payback periods calculated for these
options did not exceed a "rule-of-the-
thumb" 3 year value, the options appear
feasible and may be considered for
implementation.
Facility C-2
Facility C-2 is a small shop located in
Southern California whose main business
is refinishing decorative items. The
principal metals plated at this facility are
nickel, brass, silver, and gold.
The basic operations performed at the
plating shop include paint stripping,
cleaning, electroplating, drying, anc
polishing. All operations are performec
manually.
Table 3. Summary of Economic Feasibility Study for Facility C-1A/B
Control
Category
Drag-out
Minimization
Waste
Reduction
Method
Use of drain boards
Use of drain boards/
impurity removal
Use of drain boards/
Waste
Reduction
90
90
90
Capital
Cost
890
1103
7030
Monthly
Cost
($/month)
—
1820
Monthly
Savings
($/month)
784
784
784
Pay-back Period
(month)
1.1
—
9.0
Bath Life Extension
Rinse Water
Minimization
mechanical agitation
Still rinsing
— Copper
— Cadmium
— Silver
Impurity removal
Mechanical agitation
Spray rinsing
40
40
40
50
560
1680
2800
213
6140
11685
1820
202
58
89
440
2.8
2.4 yrs
2.6yrs
2.2 yrs
4
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Cyanide-bearing waste is generated
from silver stripping, from silver, gold,
brass, and copper electroplating, and from
the associated rinsing operations. The
principal waste streams include waste-
water (e.g., overflows from the continuous
rinse tanks and water used for floor
washings) and plating tank filter waste.
Wastewaters from non-cyanide sources
such as paint stripping, buffing, and floor
washing, and from electroplating opera-
tion are routed to a common sump. The
contents of the sump (approximately
300-400 gallons of sludge) are pumped
out periodically and disposed of as
hazardous waste. Owing to high drag-out
rate, plating solutions are adequately
purged and thus need not be replaced on
a periodic basis.
A total of 23 options were initially
postulated for the reduction of cyanide-
bearing waste from the plating shop. As
was the case for facility C-1A/B, the WM
options were grouped into six categories:
drag-out minimization; bath life extension;
rinse water minimization; substitution of
non-cyanide solutions; good operating
practices; and plant layout alterations.
Most of the proposed options are the
same as those proposed for facility C-
1 A/IB, with the exception of the options
involving good operating practices and
plant layout alteration (both are site-
specific measures). The options were
rated by the project staff and were then
presented to the facility personnel for
review.
High-ranking options were selected for
feasibility evaluation. These included
reduction of drag-out using drain boards,
extension of bath life through the use of
deionized water, reduction of water usage
using spray rinsing, and use of plastic
media blasting instead of paint stripping
(in conjunction with waste stream segre-
gation). Table 4 presents a summary of
the results obtained from the economic
feasibility study of these options.
A preliminary feasibility study was
performed for 4 waste reduction options
selected from among 23 options initially
considered. Of these four options, only
spray rinsing appears to be economically
unviable. The other options appear
feasible and may be considered for future
implementation.
Observations and
Recommendations
The following observations and recom-
mendations were made as the result of
the pilot audits:
• For the two facilities audited, the
availability of the required process
documentation was not satisfactory.
Experience with these and other sites
indicated that the availability and
quality of the information varies
significantly. Much information is
available, however, from outside
sources such as vendors, chemical
suppliers, and literature.
• Pre-audit activities, particularly the
pre-audit site visits, were found to
be extremely important in facilitating
the audit process. Cooperation by the
plant staff was improved when the
audit team spent more time getting
to know the host facility staff and
how their organization functioned.
• Participation in the options ratings
process is much improved when the
host facility personnel are required
to independently develop ratings of
each of the WM options under
consideration.
• Good operating practices recom-
mendations must be presented with
their economic dimension stressed
in order to retain the interest of the
host facility personnel. Otherwise,
they can be seen as trivial and trite.
This Project Summary was prepared by staff of Versar, Inc.. Springfield. VA.
Harry M. Freeman is the EPA Project Officer (see below).
The complete report, entitled "Waste Minimization Audit Report. Case Studies
of Minimization of Cyanide Waste from Electroplating Operations," (Order
No. PB 87-229 662/AS; Cost: $18.95. subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
Table 4. Summary of Economic Feasibility Study for Facility C-2
Description
of
Options
1. Drag-out
Minimization
2. Extension of
Bath Life*
3. Rinse water
Minimization
4. Good Operating
Practices
Method
Use of drain boards
Use of deionized water
Use of spray rinsing
Use of plastic media
blasting
Percent
Waste
Reduction
1%)
50
50
50
90
Capital
Cost
($)
315
582
2,825
17.900
Monthly
Cost
($/month)
.
38
2.519/yr
Monthly
Savings
IS/month)
241
241
29
6.607 /yr
Pay-back Period
(month)
1.3
2.9
8. 1 years
4.4 years
* Economic analysis was performed in conjunction with the implementation of drain boards.
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United States Center for Environmental Research BULK RATE
Environmental Protection Information . POSTAGE & FEES FAID
Agency Cincinnati OH 45268 EPA
PERMIT N
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