United States
Risk Reduction
Environmental Protection
Agency
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S-94/014 September 1994
ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a Manufacturer
of Coated Parts
Harry W. Edwards*, Michael F. Kostrzewa*,
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 waste but who lack
the expertise to do so. In an effort to assist these manufactur-
ers, Waste Minimization Assessment Centers (WMACs) were
established at selected universities, and procedures were
adapted from the EPA Waste Minimization Opportunity As-
sessment Manual (EPA/625/7-88/003, July 1988). That docu-
ment has been superseded by the Facility Pollution Prevention
Guide (EPA/600/R-92/088, May 1992). The WMAC team at
Colorado State University performed an assessment at a plant
that produces specialty coated parts—approximately one mil-
lion per year. Special-purpose coatings such as chromate con-
version, zinc phosphating, and paint are applied to
customer-supplied aluminum, steel, and plastic parts. The team's
report, detailing findings and recommendations, indicated that
rinse water is the waste stream generated in the greatest
quantity and that significant waste reduction could be achieved
by redirecting the effluent from one rinse to another.
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 University City Science Center, Phila-
delphia, PA.
* Colorado State University, Department of Mechanical Engineering, Fort Collins,
CO
"University City Science Center, Philadelphia, PA
Introduction
The amount of waste generated by industrial plants has be-
come an increasingly costly problem for manufacturers and an
additional stress on the environment. One solution to the
problem of waste generation is to reduce or eliminate the
waste at its source.
University City Science Center has begun a pilot project to
assist small and medium-size manufacturers who want to
minimize their generation of waste but who lack the in-house
expertise to do so. Under agreement with EPA's Risk Reduc-
tion Engineering Laboratory, the Science Center has estab-
lished three WMACs. This assessment was done by engineering
faculty and students at Colorado State University's (Fort Collins)
WMAC. The assessment teams have considerable direct ex-
perience with process operations in manufacturing plants and
also have the knowledge and skills needed to minimize 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 $75 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 and re-
duction of waste treatment and disposal costs for participating
plants. In addition, the project provides valuable experience for
graduate and undergraduate students who participate in the
program and a cleaner environment without more regulations
and higher costs for manufacturers.
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Methodology of Assessments
The waste minimization assessments require several site visits
to each client served. In general, the WMACs follow the proce-
dures outlined in the EPA Waste Minimization Opportunity
Assessment Manual (EPA/625/7-88/003, July 1988). The WMAC
staff locate the sources of waste in the plant and identify 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 tech-
nological and economic information is developed. Finally, a
confidential report that details the WMAC's findings and recom-
mendations (including cost savings, implementation costs, and
payback times) is prepared for each client.
Plant Background
This plant produces specialty coated aluminum, steel, and
plastic parts. It operates 2,210 hr/yr to produce approximately
1 million units.
Manufacturing Process
The plant operates as a job shop to apply special purpose
surface coatings to customer-supplied parts. The specific jobs
and raw materials used vary widely over time. Coatings applied
to the parts include chromate-conversion, zinc phosphating,
and organic coatings, including paints and specialized coat-
ings.
Parts that receive conversion coatings are first cleaned in a
heated alkaline bath, rinsed, desmutted in a nitric/sulfuric acid
solution, and rinsed again. Then the parts are immersed in a
heated chromic acid solution to form a corrosion-resistant coat-
ing, rinsed again, and air dried.
Parts that receive zinc phosphate coatings are first cleaned in
a heated alkaline bath and rinsed. Then the parts are soaked
in the zinc phosphating bath to impart a protective coating,
rinsed, and soaked in a sealing rinse.
Several dry paint booths are used to apply other coatings
including solvent-based paints and EMF shielding. Primer ap-
plication occurs first and is followed by two applications of
topcoat. Following paint application the parts are passed through
an oven, touched up as needed, and inspected.
Figure 1 depicts the processes used in this plant and the waste
streams generated.
Existing Waste Management Practices
This plant already has implemented the following techniques to
manage and minimize its wastes:
• High volume, low pressure (HVLP) paint guns are used for
most painting to reduce overspray. The plant reported that it
has realized paint usage reductions of 30-35% and savings
of over $50,000/yr since implementing this practice.
• Operators use care in raising parts bins slowly from process
solutions and allow sufficient drainage time to reduce drag-
out.
• Some solvents are recovered onsite for reuse.
Waste Minimization Opportunities
The type of waste currently generated by the plant, the source
of the waste, the quantity of the waste, the waste management
method, and the annual waste management cost are given in
Table 1.
Table 2 shows the opportunities for waste minimization that the
WMAC team recommended for the plant. The minimization
opportunity, the type of waste, the possible waste reduction
and associated savings, and the implementation cost along
with the payback time are given in the table. The quantities of
waste currently generated by the plant and possible 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 also should 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 may result
when the opportunities are implemented in a package.
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.
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Steel
parts from
customers
Aluminum
parts from
customers
Zinc
phosphating
• Alkaline cleaner
• Zinc phosphating
• Rinse
• Seal rinse
Spent process
solutions and rinse
water discharged
to sewer
Chromate
conversion coating
• Alkaline cleaner
• Rinse
• Desmut
• Chromating
• Rinse
Plastic
parts from
customers
Painting
• Masking
• Coating application
• Oven cure
• Inspection, unmasking
Evaporated
solvents
Waste solvent
and waste paint
to offsite incineration
Coated parts
returned to customers
Figure 1. Abbreviated process flow diagram.
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United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/S-94/014
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