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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