United States
Environmental Protection
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
  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

  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

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

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
                                        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

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
Post-Audit      8.  Technical and economic feasibility
               9. Final report preparation
                                            needs list/inspection agenda


                                            facility and process description

                                            waste description

                                            rationale for selection


                                            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

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
 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

Extension of bath life
    Drag-in reduction
    Deionized water
    Impurity removal
    Rack maintenance

    Return solution

Minimization of rinse water
    Automatic flow control
    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
    Spill and leak prevention
    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

 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.

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
                                     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
                                   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
 Table 3.   Summary of Economic Feasibility Study for Facility C-1A/B

Use of drain boards
Use of drain boards/
impurity removal
Use of drain boards/

Pay-back Period

Bath Life Extension
 Rinse Water
mechanical agitation

Still rinsing

Impurity removal

Mechanical agitation

Spray rinsing



2.4 yrs
2.2 yrs

  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
  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

Observations and
  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
  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

1. Drag-out
2. Extension of
Bath Life*
3. Rinse water
4. Good Operating

Use of drain boards

Use of deionized water

Use of spray rinsing

Use of plastic media















6.607 /yr

Pay-back Period


8. 1 years

4.4 years

* Economic analysis was performed in conjunction with the implementation of drain boards.

United States                        Center for Environmental Research                                            BULK RATE
Environmental Protection               Information                                                 .         POSTAGE & FEES FAID
Agency                             Cincinnati OH 45268                                                          EPA
                                                                                                        PERMIT N