United States
                         Environmental Protection
                                        Risk Reduction
                                        Engineering Laboratory
                                        Cincinnati OH 45268
                         Research and Development
                                        EPA600/S-92/010  April 1992
                         Waste Minimization Assessment for a
                         Manufacturer of Aluminum Extrusions

                               F. William Kirsch and Gwen P. Looby*
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.

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-

                         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

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

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.

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.

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.

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.

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

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-
  • 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.

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
                       Annual Waste
                     Management Cost
    Hydraulic oil sludge
    Caustic cleaning solution
    Cooling water from well
    Aluminum shavings and cuttings


    Paint overspray
    Paint and xylene sludge
    Hydraulic oil and paint sludge
    Chromate conversion solutions
    Chromium chips


    Anodizing solutions


    Aluminum and epoxy cuttings
    Epoxy resin and methylene chloride

Waste water Treatment

    Chromate sludge


    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
Off-site landfill
Sold to recycler
Sold to recycler
      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
* Quantity and cost not available
' Revenue received
                                                                    •jSrUS. GOVERNMENT PRINTING OFFICE: 1992 - 64H-080/40Z55

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
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
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