United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-91/067 Feb. 1992
Project Summary
Evaluation of Five Waste
Minimization Technologies at the
General Dynamics Pomona
Division Plant
Lisa M. Brown and Robert Ludwig
Eight waste reduction technologies
encompassing five industrial process
areas at the General Dynamics Pomona
Division (GDPD) were technically and
economically evaluated under the Cali-
fornia/U.S. Environmental Protection
Agency (EPA) Waste Reduction Innova-
tive Technology Evaluation (WRITE) Pro-
gram. Evaluations were made through
site visits and followup discussions with
GDPD staff and equipment suppliers.
The technologies included (1) com-
puterized printed circuit board plating;
(2) sulfuric acid anodizing; (3) robotic
paint facility operations with (a) propor-
tional paint mixing, (b) water-based sol-
vent replacement, (c) electrostatic paint
spraying, and (d) solvent distillation; (4)
bead-blast paint stripping; and (5) Freon'
recovery.
Overall, there was a decrease in haz-
ardous waste generation and an in-
crease in productivity or reuse of
recycled materials. In most cases, the
technologies could be easily transferred
to other industries except for the pro-
hibitive costs of the computerized cir-
cuit board and some processes within
the robotic paint operation. The payback
period estimates ranged from less than
a year for the Freon recovery still to 67
yr for the sulfuric acid anodizing sys-
tem. Difficulties in estimating payback
periods resulted mainly from the un-
' Mention of trade names or commercial products does
not constitute endorsement or recommendation for
use.
availability of company-sensitive infor-
mation.
This Project Summary was devel-
oped by EPA's Risk Reduction Engi-
neering Laboratory, Cincinnati, OH, and
California's Department of Toxic Sub-
stances Control, Sacramento, CA, 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
This study, performed under the Cali-
fornia/EPA WRITE Program, was a coop-
erative effort among EPA's Risk Reduction
Engineering Laboratory (RREL), the Cali-
fornia Department of Toxic Substances
Control (DTSC), and GDPD whose waste
minimization processes are the subject of
this report.
GDPD builds various tactical defense
weapons, primarily air defense missiles
and gun systems. In 1984 General Dy-
namics established a corporate environ-
mental program with individual division
responsibility for hazardous waste reduc-
tion, including reductions in the use of
toxic substances.
As a result of implementing this corpo-
rate policy, several waste reduction pro-
cess modifications have been instituted at
the Pomona Division. GDPD has reported
a reduction of 97% in the annual discharge
of hazardous (about 10,600 tons), liquid,
and solid wastes and 95% in volatile or-
ganic contaminant (VOC) emissions (about
Vv Printed on Recycled Paper
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17.5 tons) through a combination of waste
reduction and treaitment technologies.
Of the 14 waste minimization technolo-
gies recently employed at GDPD, only 5
process areas encompassing 8 technolo-
gies were evaluated: (1) computerized
printed circuit board plating; (2) sulfuric
acid anodizing; (3) robotic paint facility with
(a) proportional paint mixing, (b) water-
based solvent replacement, (c) electrostatic
paint spraying, and (d) solvent distillation;
(4) bead-blast paint stripping; and (5) Freon
recovery.
Technologies
The 14 waste minimization technolo-
gies employed at GDPD were screened for
technology applicability, source reduction
potential, extent of process modification,
and cost-effectiveness. The Worth Assess-
ment Model that was used was developed
by EPA specifically for the WRITE Pro-
gram. As a result of applying the model,
the five process areas encompassing the
eight individual technologies were chosen
for further analysis.
Technical and economic evaluations
were conducted during site visits, and the
additional information required was ob-
tained through subsequent followup con-
versations with GDPD staff and system
suppliers. As economic objectives were
centered around return on capital, internal
rate of return, and payback periods, which
are considered company sensitive infor-
mation, a simple payback for each process
was calculated.
Technology Descriptions and
Evaluations
Printed Circuit Board Plating
System
Chemcut Corporation installed a new
computerized printed circuit board plating
system at GDPD in July 1988, at a cost of
$4,100,000. This new plating system com-
pletely eliminated rinse tanks from the pro-
cess by use of a unique spray-rinse
configuration contained in a transporter
hoist system that passes over the plating
bath tanks. This computerized hoist sys-
tem allows the circuit boards to be rinsed
for only a short time after being immersed
in a process solution. The rinse water dis-
charge from this new process is less than
10 gpm versus 60 gpm from the old pro-
cess. This reduction in wastewater dis-
charge allowed for a corresponding
reduction in the size of the metal recovery
system. The use of a spray rinse versus a
dip rinse can also be a major design factor
if water supply limitations must be consid-
ered or if space is limited in locating the
plating line.
The new system employs copper
spheres in anode baskets rather than the
conventional anode bar-and-hook system
that was used in the old plating system.
This allows a 1-to-1 ratio of anode-to-cath-
ode for a very even plating across the
panel and through the holes.
When the new production equipment
was installed, Chemcut Corporation was
required to provide a nonsludge-producing
treatment system for all waste streams
generated by the process. This resulted in
a new copper-recovery system using short-
bed ion exchange columns and electro-
winning technologies. The system now
produces salable scrap copper metal and
eliminates a major waste stream to the
conventional sludge-producing waste treat-
ment system.
The difference in the cost of labor and
waste treatment between the newly in-
stalled printed circuit board plating system
and the original one resulted in a favorable
net annual operating savings. The payback
period for the new system was estimated
to be 8.3 yr. Annual cost savings of
$130,000 in waste treatment and disposal
were determined from the recovery of cop-
per from rinse water and process tank
solutions, which had previously been
treated and disposed of as a hazardous
sludge. An annual cost savings for water
use was estimated to be $10,000 based
on a net overall decrease in rinse water
discharges of 50 gpm.
Sulfuric Acid Anodizing System
In December 1988, GDPD replaced its
35-yr-old chromic acid aluminum anodiz-
ing system with a new computerized sulfu-
ric acid anodizing system—one that utilizes
computerized hoists and on-demand rins-
ing. The new system, supplied by NAPCO,
Inc., enabled GDPD to eliminate a major
source of chromium emissions.
GDPD used chromic acid in the original
aluminum anodizing process because of
military contract specifications. Typically,
when parts are either subject to stress or
contain blind holes (e.g., trapped areas,
recesses, porous castings) in which anod-
izing solution could be entrapped, the much
less corrosive chromic acid is used. Chro-
mic acid is also used to detect fine surface
flaws on finished parts. This process, in
spite of its higher operating costs, is used
by the aerospace industry, the military,
and military contractors.
General Dynamic's motivation for con-
verting to a sulfuric acid anodizing sys-
tem was that its original chromic acid
system could not be modified cost-effec-
tively to meet production requirements
and maintain compliance with current and
anticipated air and water regulatory re-
quirements. General Dynamics had deter-
mined that it was not possible to meet
proposed air emission requirements (99.8%
removal efficiency for chrome discharged
to the atmosphere) with their original pro-
cess. In addition, General Dynamics was
committed to eliminating all wastewater
discharges of chromium to ensure compli-
ance with the California Safe Drinking Wa-
ter and Toxic Enforcement Act of 1986
(Proposition 65), which prohibits an indus-
try from discharging detectable levels of
hazardous chemicals, including chromium,
into any source of drinking water. Because
GDPD's industrial wastewater discharges
to a local publicly owned treatment works
(POTW) which then uses the treated efflu-
ent for groundwater recharge, there was a
concern that the Pomona Division could
not maintain compliance with the law while
continuing to operate a chromic acid anod-
izing process.
In addition to chemical substitution to
eliminate chromium releases, adding the
automated hoists and the on-demand wa-
ter bath rinse system helped reduce waste-
water treatment requirements. The
computerized automated hoists monitor the
time intervals that parts are treated and
then allowed to drain. When compared
with manual immersion and parts draining,
this system reduces treatment requirements
by avoiding unnecessary drag-out of im-
mersion fluids to downstream rinse tanks.
Subsequently, the on-demand water rinse
system helps reduce rinse water use and
wastewater treatment requirements by re-
ducing water consumption and by monitor-
ing the conductivity of the rinse water in
the tank. Unlike manually operated rinse
tanks, which have constant overflows, the
on-demand system adds water only when
the conductivity of the tank exceeds a set
value. By using this on-demand water pro-
cess, rinse water requirements were re-
duced from approximately 15 to 20 gpm to
approximately 6 to 8 gpm. Spray rinsing is
an alternative approach to on-demand im-
mersion rinsing; however, in this case im-
mersion rinsing was required to maintain
coating performance with complex and vari-
able parts configuration.
This sulfuric acid anodizing system is
capable of retrieving samples from several
process baths, performing the required
chemical analysis, calculating the amount
of feed material needed, and activating a
chemical feed system to provide the nec-
essary amount of material needed. This
system is also capable of continuously
monitoring and automatically controlling
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physical process parameters such as bath
temperatures, rinse water quality, voltage,
and current density. The advantages in-
clude lowered labor costs, (i.e., fewer labo-
ratory personnel and machine operators),
improved worker health and safety, im-
proved productivity, improved product qual-
ity, lowered chemical usage, lowered
production wastes, and minimized process
waste.
The capital cost of the new sulfuric acid
anodizing system was $955,000 and in-
cluded the computerized hoist and on-de-
mand anodizing rinse systems. The
operating and maintenance costs were
lower for the new system when compared
with those of the old chromic acid system
because it is less energy intensive, it has a
smaller plating interval, and wastewater
treatment costs are less. Because sulfuric
acid is much more conductive as an elec-
trolyte, the anodizing process requires less
power. The cost savings for electricity were
estimated to be $10,900, based on an
annual decrease in electrical consumption.
The sulfuric acid process is also much
faster than chromic acid, so less process
time is needed for a given film thickness.
The increased throughput potential results
in lower operating costs.
Wastewater treatment costs are less
for the new system due to a decrease in
metals removal requirements. The sulfuric
acid process requires only aluminum re-
duction and results in a nonhazardous
sludge; the chromic acid system required
aluminum and chromium reduction and the
additional tanks and chemicals for treat-
ment and settling. The disposal costs for
the aluminum sludges generated from the
sulfuric acid process are less than the
hazardous chromium and aluminum sludge
generated from the chromic acid process.
The computerized hoists and on-de-
mand spray rinse systems realize addi-
tional cost savings. Both of these systems
have reduced labor requirements; water
consumption has been reduced from 20 to
8 gpm. The cost savings in reduced water
consumption has been estimated to be
$2,300 annually. GDPD also expects the
computerized hoist system to lower costs
associated with rejects and rework.
Robotic Paint Facility
The GDPD paint production operations
facility was completed in December 1988
to replace manual mixing and hand spray-
ing of metal parts in naval weapons sys-
tems. It includes computer-controlled robots
(a GRI OM 5000 Unit) that allow quick,
automated precision painting. A propor-
tional paint mixer was also added; this
feeds preselected quantities of individual
paint components directly to a paint spray
nozzle thus eliminating batch makeup op-
erations. Electrostatic spray guns and au-
tomatic waste cleaning solvent collection
systems were also introduced to allow for
recycle and reuse of waste paint. Spray
paint booths are also available for touch-
ups. Stills are used for recycling paint clean-
ing solvents.
The painting facility uses both oil- and
water-based paints. For oil-based paints,
polyurethane thinner is used for paint thin-
ning and equipment cleaning. A thinner
containing isopropyl alcohol and xylene is
used with water-based paint. Paint waste
was reduced from 42 tons in 1987 to 31
tons in 1988 and was further reduced to 17
tons in 1989. About 1,000 gal of polyure-
thane cleaning solvent per year is now
being recycled through the paint shop sol-
vent stills; this results in approximately 60
to 100 Ib of still bottoms per week or about
5,000 Ib/yr. The still bottoms and waste
paint are sent offsite for incineration.
Paint purchases decreased from 6,530
gal in 1988 to 5,230 in 1989; solvent pur-
chases decreased from 2,500 gal in 1988
to 1,080 gal in 1989. These decreases are
mainly due to changes in equipment and
operating purchases in the paint shop but
are also partially due to changes in inven-
tory and a decrease in production rates.
Only polyurethane solvent (for oil-based
paints) is currently being recycled in the
stills. When distilling the water-based paint
solvent, which contains isopropyl alcohol
and xylene, the recycled solvent separates
into two layers, a water and a solvent
layer. Even when the water is removed by
draining, water contained within the sol-
vent prevents the solvent from being re-
used for thinning and cleaning. Potentially,
the water can be removed by adding a
water separator upstream and a molecular
sieve downstream of the stills.
The installation cost of the robotic paint-
ing system was $1,400,000. The system
included a parts conveyor, computer-con-
trolled robots, electrostatic spray guns, pro-
portional paint mixing, and cleaning solvent
collection equipment. The disposal of 42
tons of waste in 1987 would have cost
about $73,000 at the current disposal rates
of $420 per drum, plus $7,000 per truck-
load for transportation (80 drums). The
disposal costs of 21 tons in 1989 would be
about $36,000. The payback period from a
waste disposal standpoint alone would be
40 yr. This substantially overstates the
payback period, however, because the sav-
ings in labor costs from painting and waste
disposal and any decrease in rejects in
parts were not included, as it was consid-
ered company sensitive information.
Payback for the solvent stills is only about
4 yr, but it would be less if all cleaning
solvent were being recycled.
Bead-Blast Paint Stripper
The plastic bead-blast paint stripper at
GDPD was installed in June 1988 to re-
place methylene chloride stripping. Reus-
able plastic beads or media are used in
this mechanical stripping operation, which
is similar to sand blasting. Paint is stripped
from the hangers used to hold parts being
painted in the paint shop and from parts
having paint defects.
The plastic bead-blasting booth is a
Pauli and Griffin Pram Machine approxi-
mately 3ftx3ftx3ft and uses size 20 to
30 mesh Poly Plus beads. The unit is used
only on an as-needed basis, generally a
few hours per week.
The waste generated during the opera-
tion of the plastic-bead blasting unit, which
consists primarily of paint chips with a
small amount of spent plastic beads, is
sent offsite for incineration. Stripping by
methylene chloride resulted in about 10,000
Ib/yr of toxic solvent contaminated with
paint sludge, which was also sent offsite
for incineration. The bead-blast paint strip-
per was installed at a cost of $18,000. This
system eliminated the disposal of the sol-
vent. Both the methylene chloride and
bead-blast waste are disposed of by incin-
eration; the annual waste disposal costs
are $10,000 for methylene chloride and
$5,000 for bead-blast waste. The plastic
bead-blast paint spripper provides a cost
savings of $5,000/yr. The payback period
from a waste disposal perspective is about
3.6 yr. This does not consider differences
in operator time, maintenance require-
ments, and stripping materials that will vary
depending on parts being stripped, whether
methylene chloride stripping is being done
by spray-on or dip tank methods, operator
skill, and recovery of stripping material.
Freon Recovery Stills
Three Freon recovery stills manufac-
tured by Recyclene were installed in De-
cember 1988 to collect and distill waste
from solvent degreasing operations
throughout GDPD at a cost of $240,000,
plus $40,000 for add-on equipment to ad-
dress operating problems. Recovered sol-
vent is tested and reformulated under a
quality assurance program to ensure that
all the manufacturer's specifications are
met before returning the solvent to material
stores for reissue to production operations.
Still bottoms are dried in the distillation
process and sent offsite for incineration.
Before installing these stills, a single
Freon recovery still was installed in No-
•&U.S. GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40151
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vember 1985 to extend the life of Freon
used in conveyorized cleaners. This ex-
tended the solvent change out period to
once per year and annually saved 35,000
Ib in Freon purchases.
Tests of the Freon recovery stills in
1988 indicated that the distillation process
was working but that the Freon being re-
cycled was contaminated with water, which
degraded the quality of the recovery prod-
uct. The Pomona Division has installed
separators to remove water and molecular
sieves to further dry the Freon after distilla-
tion. Although the additions to each still
cost $13,000, plus installation, they allow
the Freon recovery to be operated as
planned to produce a quality recycled sol-
vent.
Reduction in Freon purchases through
1988 have primarily come through improved
operating procedures such as extended
change out times for Freon and reduced
evaporative losses. A baseline of 421,000
Ib of Freon for 1988 was used to calculate
the reduced Freon use that is attributable
to the three Freon stills; it is assumed they
were utilized at full capacity for the first
time in 1989. The capital cost of the stills
was $270,000 with annual operating costs
considered negligible. The amount of Freon
recycled or the amount of avoided pur-
chases were 212,473 Ib, the cost of which,
at $1.64/lb, was $348,456. The cost to
incinerate 11,183 Ib of still bottoms was
$8,000 with a cost savings from avoided
Freon disposal equal to $148,583. The
total savings were $489,039 with a payback
period of 0.55 yr. This is a minimum
payback number based on recycling all of
the Freon that is not lost through evapora-
tion and drag-out losses.
Conclusions
Under the EPA/California WRITE Pro-
gram, five waste minimization technolo-
gies were evaluated at the GDPD. The
level of technology varied from a comput-
erized printed circuit board system costing
$4.1 million to a bead-blast paint stripper
costing $10,000. The range of payback
periods also varied—from a high of 67 yr
for the sulfuric acid anodizing system to a
low of 0.55 yr for the Freon recovery stills.
The full report was submitted in fulfill-
ment of Contract No. 68-03-3389 by PEI
Associates, Inc., under the sponsorship of
the U.S. Environmental Protection Agency.
This Project Summary was prepared by Lisa M. Brown (also the EPA Project Officer,
see below) of the Risk Reduction Engineering Laboratory, Cincinnati, OH 45268, and
Robert Ludwig of the State of California Department of Toxic Substances Control,
Sacramento, CA 94234-7320, based on the draft report by PEI Associates, Inc.
The complete report, entitled "Evaluation of Five Waste Minimization Technologies at
the General Dynamics Pomona Division Plant," (Order No. PB92-125756/AS; Cost:
$19.00, 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:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA PERMIT NO. G-35
Official Business
Penalty for Private Use $300
EPA/600/S2-91/067
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