vvEPA
United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati OH 45268
Research and Development
EPA600/S-92/010 April 1992
ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a
Manufacturer of Aluminum Extrusions
F. William Kirsch and Gwen P. Looby*
Abstract
The U.S. Environmental Protection Agency (EPA) has funded
a pilot project to assist small- and medium-size manufacturers
who want to minimize their generation of hazardous waste but
who lack the expertise to do so. Waste Minimization Assess-
ment Centers (WMACs) were established at selected universi-
ties and procedures were adapted from the EPA Waste Minimi-
zation Opportunity Assessment Manual (EPA/625/7-88/003, July
1988). The WMAC team at the University of Louisville per-
formed an assessment at a plant manufacturing aluminum
extrusions — over 10 million Ib/yr. Aluminum parts are ex-
truded and tempered followed by electrostatic painting, anodiz-
ing, or shipping. The team's report, detailing findings and
recommendations, indicated that the most waste was gener-
ated by the painting process and that the greatest savings
could be obtained by replacing the currently used paints with
electrostatic powder coatings.
This Research Brief was developed by the principal investiga-
tors and EPA's Risk Reduction Engineering Laboratory, Cincin-
nati, OH, to announce key findings of an ongoing research
project that is fully documented in a separate report of the
same title available from the authors.
Introduction
The amount of hazardous waste generated by industrial plants
has become an increasingly costly problem for manufacturers
and an additional stress on the environment. One solution to
the problem of hazardous waste is. to reduce or eliminate the
waste at its source.
' University Cfty Science Center, Philadelphia, PA 19104
University City Science Center (Philadelphia, PA) has begun a
pilot project to assist small- and medium-size manufacturers
who want to minimize their formation of hazardous waste but
who lack the in-house expertise to do so. Under agreement
with EPA's Risk Reduction Engineering Laboratory, the Sci-
ence Center has established three WMACs. This assessment
was done by engineering faculty and students at the University
of Louisville's WMAC. The assessment teams have consider-
able direct experience with process operations in manufactur-
ing plants and also have the knowledge and skills needed to
minimize hazardous waste generation.
The waste minimization assessments are done for small- and
medium-size manufacturers at no out-of-pocket cost to the
client. To qualify for the assessment, each client must fall
within Standard Industrial Classification Code 20-39, have gross
annual sales not exceeding $50 million, employ no more than
500 persons, and lack in-house expertise in waste minimiza-
tion.
The potential benefits of the pilot project include minimization
of the amount of waste generated by manufacturers, reduced
waste treatment and disposal costs for participating plants,
valuable experience for graduate and undergraduate students
who participate in the program, and a cleaner environment
without more regulations and higher costs for manufacturers.
Methodology of Assessments
The waste minimization assessments require several site visits
to each client served. In general, the WMACs follow the
procedures outlined in the EPA Waste Minimization Opportu-
Printed on Recycled Paper
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nty Assessment Manual (EPA/625/7-88/003, July 1988). The
WMAC staff locates the sources of hazardous waste in the
plant and identifies the current disposal or treatment methods
and their associated costs. They then identify and analyze a
variety of ways to reduce or eliminate the waste. Specific
measures to achieve that goal are recommended and the
essential supporting technological and economic information is
developed. Finally, a confidential report that details the WMAC's
findings and recommendations (including cost savings, imple-
mentation costs, and payback times) is prepared for each
client.
Plant Background
This plant manufactures painted, anodized, and mill-finished
aluminum extrusions. Over 10 million Ib of aluminum extru-
sions are produced each year by the plant's 100 employees
who operate the plant approximately 4000 hr/yr.
Manufacturing Process
The manufacturing processes of this plant and the wastes
generated are described below.
Extrusion
Three extrusion presses are used to produce aluminum parts.
Aluminum billets are processed in two of the presses. First,
the billets are coated with an extrusion compound to reduce
friction and heated to 900°F in a furnace. Then the billets are
extruded through the appropriate die and the ends of the billets
are cut off. The resulting parts are then moved to a cooling
station prior to age-hardening.
Aluminum logs are processed in the third press, which is
computer-controlled. These logs are also coated and heated
to 9008F prior to extrusion. The logs are extruded and cut to
size as determined by the control system. The resulting parts
are cooled before age-hardening.
The cooled, extruded parts are tempered in ovens at 365°F for
4 hr (age-hardening). The parts are then sent to painting,
anodizing, or directly to shipping.
Several wastes are generated by the extrusion process. Alu-
minum shavings and billet ends are recycled by a sister plant.
The caustic solution that is used to clean the extrusion dies is
sent to the on-site wastewater treatment plant. Waste hydrau-
lic fluid from the presses is recycled on-site; sludge from the
recycler is landfilled. Wastewater from the cooling of the
extrusion presses is disposed of through a storm sewer drain.
Painting
Parts that require painting are hung on an overhead conveyor.
Prior to painting, the parts are run through a conversion coat-
ing system in which a coat of chromium phosphate is bonded
to part surfaces for corrosion protection. Parts are dried in a
25Q°F oven.
After drying, the parts are electrostatically painted in one of two
paint booths. Paint is cured in a 350°F oven. Selected parts
are then tested. Most of the failed parts are scrapped, but
some failed parts are reworked.
Waste generated by the painting process includes wastewater
from the conversion coating process that is sent to the onsite
wastewater treatment plant. Chromate chips that result from
the cleaning of the solution mixing tank are disposed of in a
hazardous waste landfill. A significant amount of overspray
paint waste is disposed of in a nonhazardous landfill. Sludge
containing xylene and paint results from the cleaning of the
paint atomizer parts and is disposed of as a hazardous waste.
Hydraulic oil that leaks from the atomizers mixes with paint and
xylene in the paint booths and is disposed of in a nonhazardous
waste landfill. Used filters from the booths are disposed of in
the dumpster with other miscellaneous trash.
Anodizing
Parts to be anodized are degreased, rinsed, etched, rinsed
again, and then dipped into the anodizing tank. After anodi;:-
ing, the parts are rinsed and dipped in a seal tank. Waste
solutions from the anodizing line are sent to the onsite WWTP.
Thermalfilling
Painted and anodized parts which will be used in household
windows and doors are sent to the thermalfill line. In this
process, the cavity of the part is filled with epoxy. Once the
parts have dried, a portion of the metal and epoxy is removed
to create a discontinuity, thereby providing greater insulation
potential.
Waste epoxy resin, aluminum and epoxy cuttings, and waste
methylene chloride, which is used to clean the epoxy discharge
nozzles, are disposed of in the dumpster.
Existing Waste Management Practices
This plant has already taken the following steps to manage and
minimize its wastes:
• The computer-controlled extrusion press operates more
efficiently and generates less waste aluminum than
standard extrusion presses. Eventually all of this
plant's extrusions will be produced by the computer-
controlled press.
• Hydraulic oil is cleaned onsite and reused.
• Scrap aluminum is reused by a sister plant.
• Waste from the conversion coating process is treated
to reduce chromium (VI) to chromium (III) before dis-
posal.
• High-solids electrostatic paint is used in the paint line
to reduce volatile organic compound (VOC) emissions
and overspray.
• An on-site wastewater treatment plant pretreats all
process wastewater prior to discharge to the public
owned treatment works (POTW).
Waste Minimization Opportunities
The waste streams currently generated by the plant, the waste
management methods applied, the quantities of waste, and the
annual treatment and disposal costs are given in Table 1.
Table 2 shows the opportunities for waste minimization that the
WMAC team recommended for the plant. Current plant prac-
tice, the proposed action, and waste reduction, savings, and
implementation cost data are given for each opportunity. The
quantities of waste currently generated by the plant and pos-
sible waste reduction depend on the production level of the
plant. All values should be considered in that context.
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It should be noted that the economic savings of the minimiza-
tion opportunity, in most cases, results from the need for less
raw material and from reduced present and future costs asso-
ciated with waste treatment and disposal. Other savings not
quantifiable by this study include a wide variety of possible
future costs related to changing emissions standards, liability,
and employee health. It should also be noted that the savings
given for each opportunity reflect the savings achievable when
implementing each waste minimization opportunity indepen-
dently and do not reflect duplication of savings that would
result when the opportunities are implemented in a package.
Additional Recommendations
In addition to the opportunities analyzed and recommended by
the WMAC, several other possibilities for waste minimization
were evaluated by the assessment team. These measures
were not completely analyzed because of insufficient data or
minimal savings. They were brought to the manufacturer's
attention for future reference, however, since these approaches
to waste minimization may increase in attractiveness with chang-
ing plant conditions.
• Recover chromium from the waste rinse waters using
ion exchange. This measure probably would not be
cost-effective because of the small amount of chro-
mium involved.
• Recover the aluminum from the caustic dip tank of the
anodizing line or arrange to sell the waste aluminum
hydroxide through a waste exchange. The recovery
of the aluminum would result in an unacceptably long
payback. It is possible that a buyer may be interested
in the waste.
• Use an alternate solvent or a non-solvent method for
cleaning the nozzles in the thermalfill line.
• Use more efficient heat exchangers for cooling the
extrusion presses.
This research brief summarizes a part of the work done under
Cooperative Agreement No. CR-814903 by the University City
Science Center under the sponsorship of the U.S. Environmen-
tal Protection Agency. The EPA Project Officer was Emma
Lou George.
Table 1, Summary of Current Waste Generation
Waste Stream Generated Waste Management Method
Annual Quantity
Generated
Annual Waste
Management Cost
Extrusion
Hydraulic oil sludge
Caustic cleaning solution
Cooling water from well
Aluminum shavings and cuttings
Painting
Paint overspray
Paint and xylene sludge
Hydraulic oil and paint sludge
Chromate conversion solutions
Chromium chips
Anodizing
Anodizing solutions
Thermalfill
Aluminum and epoxy cuttings
Epoxy resin and methylene chloride
Waste water Treatment
Chromate sludge
Miscellaneous
Metal packing bands
Empty drums
Paper, cardboard, rags, etc.
Off-site landfill
Treated onsite and sewered
Storm drain
Recycled by sister plant
Off-site landfill
Off-site hazardous waste disposal facility
Off-site landfill
Treated onsite and sewered
Off-site hazardous waste disposal facility
Treated onsite and sewered
Dumpster
Dumpster
Off-site landfill
Sold to recycler
Sold to recycler
Dumpster
5,400 Ib
57,600 gal
68,160,000 gal -
3,300 gal
55 gal
495 gal
3,720,000 gal
1,200 Ib
3,732,000 gal
42,000 Ib
15,000 Ib
33,830 gal
18,000 Ib
220 units
1,040 yd3
$ 4,210
180
0
13,680
360
1,170
11,840
920
15,040
1,370
460
13,700
(340)1
(220)'
450
* Quantity and cost not available
' Revenue received
•jSrUS. GOVERNMENT PRINTING OFFICE: 1992 - 64H-080/40Z55
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Tablo 2. Summary of Recommended Waste Minimization Opportunities
Present Practice Proposed Action
Waste Reduction and Associated Savings
Waste hydraulic oil unreclaimed after the
plant's on-site recycling process is sent to
an oti-sllo landfill.
Ship the remaining hydraulic oil to a
secondary fuels program at a lower
disposal cost Discontinue the addition
of lime kiln dust to the waste for solidification.
Waste reduction =* 2,700 Ib/yr
Waste management cost savings = $3,540/yr
Implementation cost = 0
Payback is immediate.
TTie paint spray booths operate continuously.
PaM Is sprayed during long gaps when no
parts are fed through the line.
High-solids, electrostatic paint is used
in the paint spray booths.
Wastowaterts released to the sewer
after on-site treatment.
Install optical sensors and controls to turn
off the flow of paint when no parts are being
fed through the line.
Replace the currently used paints with
electrostatic powder coatings.
Recycle the effluent from the on-site WWTP.
Waste reduction =1,650 gal/yr
Waste management cost savings = $6,840/yr
Raw material cost savings - $1,800/yr
Total cost savings = $8,640/yr
Implementation cost = $7,500
Simple payback = 0.9 yr
Waste reduction = 2,915 gal/yr
Waste management cost savings = $11,330/yr
Raw material cost savings = $12,600/yr
Total cost savings = $23,930/yr
Implementation cost= $118,000
Simple payback = 5.1 yr
Waste reduction = 5,520,000 gal/yr
Waste management cost savings = $6,790/yr
Water cost savings = $4,750/yr
Operating cost = $580/yr
Net cost savings = $10,960/yr
Implementation cost = $1,520
Simple payback = 0.2 yr
Overflow from the anodizing tank is sent
to the on-site WWTP.
Aluminum and epoxy cuttings from the
tharmalfiH Kne are disposed of hi the
dompstor.
Install an anion exchange-based acid
purification unit to recover the sulfuric
acid from the solution and return it to the
bath. Water usage will also be
reduced because it will no longer be led
continuously to the tank.
Separate the aluminum from the epoxy
in a zig-zag classifier and sell the
aluminum to the company's sister plant.
Waste reduction = 248,000 gal/yr
Waste management cost savings = $500/yr
Raw material cost savings = $5,250/yr
Total cost savings = $5,750/yr
Implementation cost = $35,000
Simple payback = 6.1 yr
Waste reduction = 21,000 Ib/yr
Waste management cost savings * $685/yr
Revenue received = $2,940/yr
Total cost savings = $3,625/yr
Implementation cost = $6,180
Simple payback = 1.7yr
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/S-92/010
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