United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-88/010 Mar. 1988
&EPA Project Summary
Waste Minimization Audit
Report: Case Studies of
Minimization of Solvent
Wastes and Electroplating
Wastes at a DOD Installation
Marvin Drabkin and Paul Sylvestri
The U.S. Environmental Protection
Agency (EPA) is encouraging hazard-
ous waste generators to develop pro-
grams to reduce the generation of
hazardous waste. To foster such pro-
grams, the Agency's Office of
Research and Development Hazardous
Waste Engineering Research Labora-
tory (ORD/HWERL) is supporting the
development and evaluation of a model
hazardous waste minimization audit
(WMA) procedure using the EPA hier-
archy of waste minimization (WM)
options, with source reduction being
more desirable and recycle/reuse less
desirable. Treatment options, although
not considered WM, are evaluated if
neither of the former alternatives is
available. The WMA procedure was
tested initially in several facilities in
1986. WM As were conducted at gener-
ators of a number of generic hazardous
wastes, including corrosives, heavy
metals, spent solvents, and cyanides.
In 1987. the HWERL WMA program
concentrated on ORD's top priority
RCRA K and F waste list. Audits were
conducted at generators of K071 and
K106 wastes (mercury cell chloralkali
plants), K048-K052 wastes (sludges
and solids from petroleum refining),
F002-F004 wastes (spent solvents),
and F006 wastes (wastewater treat-
ment sludges from electroplating oper-
ations). This Project Summary covers
a WMA carried out at a DOD instal-
lation responsible for the rehabilitation
of worn Army tanks. This audit was
aimed at developing WM options for
F002, F004, and F006 wastes.
The WMA carried out at the DOD
installation's electroplating facility
resulted in the development of three
source reduction options and two
recycle/reuse options for cadmium/
cyanide waste as well as two source
reduction options for chromium waste.
Successful implementation of appro-
priate combinations of these options
could result in the DOD installation
being able to achieve EPA delisting of
the F006 wastewater treated sludge.
Payback period for the incremental
investment needed to achieve these
WM results, could range from four
months to 1.9 years depending on the
choice of options. Savings in present
F006 waste disposal costs could
amount to $120,000 annually.
The WMA carried out at the DOD
installation's paint stripping solvent
facilities resulted in two alternative
source reduction options being deve-
loped by the audit team. Implementa-
tion of either of these two options could
result in payback period for the incre-
mental investment involved ranging
from 6 to 8 months with savings in
waste solvent disposal costs of
$53,000 annually.
This Project Summary was developed
by EPA's Hazardous Waste Engineering
Research Laboratory, Cincinnati, OH,
to announce key findings of the
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research project that is fully documented
in a separate report of the same title (see
Project Report ordering information at
back).
Introduction
The national policy objectives estab-
lished under the 1984 Hazardous and
Solid Waste Amendments to the
Resource Conservation and Recovery Act
of 1976 include the goal of reducing or
eliminating hazardous waste as expedi-
tiously as possible. To promote waste
minimization activities, the Hazardous
Waste Engineering Research Laboratory
(HWERL) of the U.S. Environmental
Protection Agency (EPA), Office of
Research and Development, has under-
taken a project to develop and test a
waste minimization audit (WMA) proce-
dure. It is envisioned that such a proce-
dure would be useful to generators of
hazardous waste as they search for
waste minimization alternatives. The
present HWERL project expands on an
audit procedure developed and tested in
1986 by conducting additional WMAs in
cooperating industrial and government
facilities. This project is one of several
current audit efforts being supported by
HWERL.
This study presents the elements of a
WM program, of which the audit proce-
dure is a central component and includes
details of the WMA procedure, its
development, and its final recommended
form. A case study is presented using
this WMA procedure, and covers audits
performed at a DOO installation that
includes facilities which generate listed
wastes F002 and F004 as well as a
facility which generates listed waste
F006. Findings and conclusions resulting
from these audits are presented below.
Description of the WMA
Procedure
The function of the WMA procedure
is to force the use of an orderly step-
by-step procedure for conducting an
audit at a host site. The initial WMA
procedure was developed in earlier work,
and was further refined during the
course of the present EPA-sponsored
audit effort. This procedure is applicable
to the development of both categories of
WM options (source reduction and
recycling/reuse) as well as to the
development of treatment options.
The team employed in carrying out the
audit described in the full report was
composed entirely of employees of an
outside consulting/engineering firm.
Following selection of the host facility
there were eight sequential steps
executed by the audit team:
1. Preparation for the audit.
2. Host site pre-audit visit.
3. Waste stream selection.
4. Host site waste minimization audit
visit.
5. Generation of WM options.
6. Preliminary WM options evaluation
(including preparation of prelimi-
nary cost estimates) and ranking of
options in three categories (effec-
tiveness, extent of current use, and
potential for future application).
7. Presentation, discussion, and joint
review of options with plant
personnel.
8. Final report preparation and pres-
entation to host site managmeent.
This procedure was followed in carrying
out the WMAs summarized below.
Results of the WMA
Conducted at a Generator of
F002 and F004 Waste: Audit
at a DOD Installation Paint
Stripping Facility
A DOD installation in the South, a
portion of whose facilities is devoted to
the rehabilitation of worn Army tanks
was studied in a WMA for the reduction
of F002 and F004 wastes. These listed
F wastes are partially defined in 40 CFK
261.32 as follows:
• F002: Spent halogenated solvents
including methylene chloride.
• F004: Spent non-halogenated sol-
vents including cresols and cresylic
acid.
At three buildings in the DOD installa-
tion, tank part paint stripping facilities
using methylene chloride solvent formu-
lationsfcontaining phenolic-type constit-
uents to enhance solvent action), gener-
ate F002 and F004 wastes. F002 and
F004 wastes include:
• Approximately 20,000 gallons per
year of spent methylene chloride-
based paint stripping solvent and
about sixty, 55-gallon drums of paint
sludge are generated in the paint
stripping operations and sent offsite
for hazardous waste disposal. Spent
solvents are presently disposed of in
bulk approximately every 6 months.
Drummed hazardous paint sludges
are shipped offsite within 90 days of
accumulation.
• Wastewaters from stripped parts
rinsing operations are sent to the
onsite wastewater treatment plant
where biological treatment is used to
reduce phenol level to meet NPDES
permit requirements prior to
discharge.
The audit team studied possible source
reduction and recycle/reuse options for
these wastes. The focus of this effort was
primarily on ways to prolong the life of
the paint stripping solvents as the most
effective short-term options. The long-
term waste reduction options, i.e.,
development of non-solvent formula-
tions and other paint removal tech-
niques, could not be meaningfully
addressed in this study.
The most promising source reduction
options for paint stripping solvent waste
reduction were:
• Continuous centrifugation of the paint
stripping solvent to remove paint
sludge as it is generated thus prevent-
ing buildup of this sludge in the
stripping tanks and significantly
extending the life of the solvent.
• As an alternative to continuous cen-
trifugation of the solvent, continuous
2-stage basket/cartridge filtration of
the solvent to prevent paint sludge
buildup.
In summary, it is believed that success-
ful implementation of either of these
options could result in solvent life being
extended to at least one year prior to
replacement. In this regard, a small scale
test by a centrifuge vendor on a sample
of spent solvent heavily loaded with paint
sludge, indicated that clear solvent could
be produced by this technique. Each of
the six main paint stripping solvent tanks
at the facility would be equipped with
either a solid-bowl type centrifuge or a
basket/cartridge type 2-stage filter.
Table 1 summarizes the results of the
preliminary technical and economic
feasibiliy study of these two options.
Annual waste solvent disposal cost
would be cut in half (approximately
$50,000 per year savings) if either of
these two options were adopted, with
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Table 1.
Tabulated Projected Costs and Required Site Modifications: WM Options for DOD Installation F002 and F004 Wastes
WM
Option^
Waste Source Option Description
Proposed Equipment
Modifications
Estimated
Estimated Annual
Installed Direct Operating
Cost($) Cost*($/yr)
Required Site
Modifications
Payback
Period
(years)
(1)
12)
Waste paint
Continuous removal
stripping solvent of paint sludge from
disposal
Waste paint
Add a pump and solid
bowl centrifuge to each
solvent (using a solid of the six paint stripping
bowl centrifuge).
Solvent replaced
annually.
Continuous removal
solvent tanks; unit
operates at about 5 gpm
flow rate.
Add a pump and two-
stage filtration unit to
solvent (using a two- each of the six paint
stage filtration unit), stripping solvent tanks
(first stage is basket type
filter for large pieces and
second stage is a porous
metal filtration cartridge
for micron-size particles).
stripping solvent of paint sludge from
disposal
Solvent replaced
annually.
50,000 5,000 Adequate floor space is 0.5
available in front of
each of these stripping
tanks to permit
installation without
major existing
equipment relocation.
60,000 9,000 Adequate floor space is 0.67
available in front of
each of these stripping
tanks to permit
installation without
major existing
equipment relocation.
1AII options shown are source reduction options.
2Other than the cost of replacing spent paint stripping solvent, which is estimated separately.
payback periods ranging from 0.5 to 0.7
year.
Results of the WMA
Conducted at a Generator of
F006 Waste: Audit at the DOD
Installation Electroplating
Facilities
Electroplating operations at the DOD
installation are conducted in one building
and include cadmium plating of miscel-
laneous cleaned and/or remachined
tank parts using cadmium/cyanide (Cd/
CN) solutions in either an automatic
barrel plating line or a manual rack
plating line. Chromium (Cr) plating of
appropriately prepared tank parts is
conducted in a rack plating line. Both
plating operations are fairly standard-
ized.
The facility has been experiencing
significant problems in meeting NPDES
permit limitations for Cd and CN in the
treated wastewater discharge. Thus, the
audit team focused primarily on waste
reduction options which could reduce or
eliminate Cd and CN levels in the raw
waste (principally rinsewaters from both
Cd plating lines). Approximately 2,000
gallons per day of these wastewaters
typically containing 20 mg/l of Cd and
25 mg/l CN are discharged from the
electroplating facility. About 35,000
gallons per day of Cr-bearing waste
averaging 110 to 120 mg/l Cr are also
discharged from this facility.
A study of the electroplating operations
that generate F006 waste (including
discussions between the audit team and
plant personnel), led the audit team to
develop a total of five WM options for
Cd/CN plating-related waste and two
WM options for Cr plating-related waste.
These options include commercially
demonstrated processing techniques
designed to minimize or eliminate Cd, Cr,
and CN levels in the rinsewater wastes
as well as reducing the amounts of
wastewater. These options together with
their estimated capital and operating
costs are summarized in Table 2. One
proposed source reduction option: elec-
trolytic reverse current destruction of CN
(both simple and complexed) in the still
rinse tanks of the two Cd plating lines
during the plant downtime period, is
currently being evaluated at the facility.
One proposed recycle/reuse option:
recovery of Cd from the two plating lines'
still rinse tanks, has since been imple-
mented and appears to have resulted in
the facility being able to consistently
meet the Cd limit in their NPDES permit.
It is believed that successful imple-
mentation of appropriate combinations of
these WM options could result in the
DOD installation being able to achieve
EPA delisting of the F006 wastewater
treatment sludge as well as meeting Cd
and CN permit limits in the NPDES
discharge. Payback periods for the
incremental investment involved range
from 6 months to 1.9 years. Savings in
the present F006 waste disposal costs
could amount to $120,000 annually if the
F006 waste can be delisted.
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Table 2. Tabulated Projected Costs: WM Options for DOD Installation F006 Wastes1
WM Option Proposed Equipment
Option Waste Source Type Option Description Modifications
(a)(1) CD/CN Barrel Plating
Line
fa)(2) Cd/CN Manual
Plating Line
(b)( 1 ) Cd/CN Barrel Plating
Line
(b)(2) Cd/CN Manual
Plating Line
(c)(1) Cd/CN Manual
Plating Line
(c)(2) Chromium Manual
Plating Line
fd) Both Cd/CN Plating
Lines
fej(l) Cd/CN Barrel Plating
Line
(e)(2) Cd/CN Manual
Plating Line
(fj Chromium Manual
Plating Line
(g) Chromium Manual
Plating tine
Source
reduction
Source
reduction
Source
reduction
Source
reduction
Source
reduction
Source
reduction
Recycle/
reuse
Recycle/
reuse
Recycle/
reuse
Source
reduction
Source
reduction
Use of electroclean rinse
waters as feed to pickling
rinse water tank
Use of electroclean rinse
waters as feed to pickling
rinse water tank
Destruction of cyanides
in still rinse tank
Destruction of cyanides
in still rinse tank
Improved dragout
recovery;
drain board, spray/fog
rinsing nozzles over
plating tank
Improved dragout
recovery; drain
board, spray/fog
rinsing
Evaporation of Cd/CN
rinse water discharge
and recycle to
both plating lines
in appropriate
quantities to
maintain individual
plating bath
water balances
Plating out of cadmium
in still rinse tank
Plating out of cadmium
in still rinse tank
Improved dragout
recovery:
replacement of running
rinse tank with spray
chamber
Reduction of chromium
metal losses from
hood vents over
plating tanks
Water piping and pump
Water piping and pump
Insertion ofSS cathodes and
anodes in still rinse tank
and operation in a CN
destruction mode during
plating line downtime
Insertion ofSS cathodes and
anodes in still rinse tank
and operation in a CN
destruction mode during
plating line downtime
Add drain board between Cd
plating tank and still rinse
tank; install spray/fog rinse
Add drain board between Cr
plating tank and still rinse
tank; install spray/fog rinse
nozzles over plating tank
Install evaporation unit and
auxiliaries in Building 114
basement near Cd/CN
waste sump
Insertion of SS cathodes and
anodes in still rinse tank
to operate in a Cd plating
mode during plating line
downtime
Insertion ofSS cathodes and
anodes in still rinse tank
to operate in a Cd plating
mode during plating line
downtime
Install suitable banks of
spray nozzles in empty
running rinse tank
Add layer of plastic balls
on surface of chromium
plating tanks
Estimated Estimated Annual
Installed Operating Cost
Cost {$)' l$/yr)
$ 1,000
1,000
2.000
2.000
1,500
1,500
79,000
Use the
same
equipment
as in (b)
Use the
same
equipment
as in (b)
5,000
Nil
$ 500
500
10,000
10,000
1,000
1,000
27.000
20,000
2O.OOO
2,000
Nil
^Order of magnitude costs (± 50 percent accuracy).
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M. Drabkin and P. Sylvestri are with Versar, Inc., Springfield, VA 22151.
Harry F. Freeman is the EPA Project Officer (see below).
The complete report, entitled "Waste Minimization Audit Report: Case Studies
of Minimization of Solvent Wastes and Electroplating Wastes at a DOD
Installation," {Order No. PB 88-166 780/AS; Cost: $14.95, 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
62SOICO'
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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•ft U S. GOVERNMENT PRINTING OFFICE. 1988-548-013/87'
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