United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S-92/020 May 1992
&EPA ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a Manufacturer of
Motor Vehicle Exterior Mirrors
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 waste but who lack
the expertise to do so. Waste Minimization Assessment Cen-
ters (WMACs) were established at selected universities and
procedures were adapted from the EPA Waste Minimization
Opportunity Assessment Manual (EPA/625/7-88/003, July 1988).
The WMAC team at the University of Tennessee performed an
assessment at a plant manufacturing exterior motor vehicle
mirrors approximately 3 million mirrors per yr. Galvanized
steel and stainless steel stock undergo stamping, pressing, and
cutting operations followed by degreasing. Stainless steel
mirror housings are buffed, assembled, packaged, and shipped.
Galvanized steel, zinc die-cast, and plastic mirror parts are
washed then electrostatically primed and painted. Parts are
assembled, packaged, and shipped. The team's report, detail-
ing findings and recommendations, indicated that the majority
of the waste was generated in the cleaning and washing areas
but that the greatest savings could be obtained by installing an
electrostatic powder coating system to reduce primer/paint
overspray (100%), solvent evaporation (55%), cleaning solvent
evaporation (80%), and still bottoms (80%).
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 waste generated by industrial plants has be-
come an increasingly costly problem for manufacturers and an
University City Science Center, Philadelphia, PA 19104
additional stress on the environment. One solution to the
problem of waste is to reduce or eliminate the waste at its
source.
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 waste but who lack the
inhouse expertise to do so. Under agreement with EPA's Risk
Reduction Engineering Laboratory, the Science Center has
established three WMACs. This assessment was done by
engineering faculty and students at the University of
Tennessee's (Knoxville) WMAC. The assessment teams have
considerable direct experience with process operations in manu-
facturing plants and also have the knowledge and skills needed
to minimize 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-
^g£> Printed on Recycled Paper
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nhy 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 th'e
essential supporting technological and economic information is
developed. Finally, a confidential reportjhat 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 exterior mirrors for motor'vehicles.
The plant operates 6,120 hr/yr to produce approximately 3
million mirrors.
Manufacturing Process
This plant takes galvanized and stainless steel stock and forms
ft into mirror housings for use on both automobiles and trucks.
Raw materials in use include sheets and rolls of galvanized
steel, stainless steel, zinc die-cast parts, plastic stock, hard-
ware, and mirror glass.
The following steps are involved in making the mirrors:
Raw materials undergo stamping, pressing, and cutting
operations to form mirror housings and arm braces.
Galvanized steel mirror housings and parts and stainless
steel mirror housings are rinsed in water to remove any
residual dirt or grease. Buffing stones are added to the
tank for parts degreasing to aid in the removal of dirt and
grease. Contaminated water from the degreasing opera-
tion is sent to the plant's on-site water treatment facility.
The degreased stainless steel mirror housings are me-
chanically buffed. Spent buffing compound, metallic waste,
and soiled cleaning rags are discarded in municipal waste.
Degreased galvanized steel parts, zinc die-cast parts, and
high temperature plastic parts are cleaned and their sur-
faces are prepared for priming and painting in a nine-stage
washer. The nine-stage washer consists of an alkaline-
wash tank followed by two water rinse tanks, a titanium
conditioner tank, a zinc phosphate-accelerator additive tank
for further surface preparation followed by a water rinse
tank, and a chromic acid rinse tank followed by two water
rinse tanks. Contaminated wash and rinse water is sent to
the on-site water treatment facility. Spent ion-exchange
columns used to produce deionized water are taken off-
site by an outside contractor.
After the nine-stage washer process, galvanized steel, zinc
die-cast, and high temperature plastic parts are electro-
statically primed, dried, electrostatically painted, and dried
again before assembly. Primer and paint overspray is
collected on plastic sheets which are disposed of in mu-
nicipal waste.
Other plastic parts are cleaned and prepared for painting
in a five-stage washer. The five-stage washer consists of
a heated water-rinse tank, three currently unused stages,
and a conductive surface treatment tank. Contaminated
water is sent to the on-site treatment facility.
Following the five-stage washer process, plastic parts are
electrostatically painted and dried before assembly. Paint
overspray is deposited on paint booth filters which are
disposed of in municipal waste.
Contaminated water received from various areas of the
plant is treated in the on-site facility. First, hydrochloric
acid is added to the water to reduce its pH. Contaminants
precipitate from the water and collect as sediment which is
piped to a filter press to remove water. The water which is
removed is directed back to the treatment tank, then
pumped to a second tank where additional sediment is
collected. That sediment is also processed in the filter
press. The water is then passed through an ion-exchange
column to remove residual heavy metals before being
released to the municipal sewer.
Existing Waste Management Practices
Only non-hazardous primer and paint products are used.
Contaminated water generated on-site is treated within the
plant before being released to the municipal sewer.
Hexavalent chrome which is used in one stage of the nine-
stage washer is converted to the less hazardous form of
trivalent chrome prior to water treatment.
A portable distillation unit recycles spent solvent generated
by the spray gun and paint-line cleaning.
Electrostatic primer and paint application systems maxi-
mize paint application efficiency.
Waste Minimization Opportunities
The type of waste currently generated by the plant, the source
of the waste, the quantity of the waste, and the annual man-
agement costs are given in Table 1.
Table 2 shows the opportunities for waste minimization that the
WMAC team recommended for the plant. The type of waste,
the minimization opportunity, 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, in most cases, the economic savings of
the minimization opportunities result from the need for less raw
material and from reduced present and future costs associated
with waste treatment and disposal. Other savings not quantifi-
able by this study include a wide variety of possible future costs
related to changing emissions standards, liability, and em-
ployee health. It should also be noted that the savings given
for each opportunity reflect the savings achievable when imple-
menting each waste minimization opportunity independently
and do not reflect duplication of sayings that would 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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Table 1. Summary of Current Waste Generation
Waste Generated Source of Waste
Contaminated wash water Degreasing of galvanized steel and
stainless steel components.
Spent buffing compound and Buffing of stainless steel components
metallic waste
Contaminated wash and rinse water Nine-stage washer.
Spent ion exchange columns Nine-stage washer.
Evaporated solvents Primer and paint application
Primer and paint overspray collected Primer and paint application.
on plastic sheets
Contaminated water Five-stage washer.
Paint overspray collected on filters Paint application.
Sediment Water treatment facility.
Evaporated solvent Spray gun and paint-line cleaning.
Still bottoms Distillation unit for recovering spray gun
and paint line cleaning solvent.
Primer and paint ash Bum-off oven for cleaning parts racks.
1~The plant reports no waste management cost associated with solvent evaporation.
Table 2. Summary of Recommended Waste Minimization Opportunities
Annual Waste Reduction
Waste Stream Reduced Minimization Opportunity Quantity Percent
Evaporated solvent and Install an electrostatic 12 bbl1 100
primer and paint powder coating system 3,076 gal2 55
overspray collected on to replace painting of gal- 766 gal3 80
plastic sheets. vanized steel and zinc 616 gal4 80
Annual Quantity Annual Waste
Generated Management Cost
142,800 gal $7,688
1,123 bbl 5,100
797, 150 gal 9,188
24 units 9,057
5,620 gal O1
12 bbl 8,925
10,200 gal 4,687
6,375 filters 8,925
162 bbl 26,688
957 gal 01
770 gal 15,097
3,825 Ib 7,687
Net Implementation Payback
Annual Savings Cost Years
$113,418 $236,880 2.1
Contaminated wash and
rinse water from the
nine-stage washer.
Evaporated solvent.
Contaminated wash and
rinse water from the
degreasing, five-stage,
and nine-stage washing
processes.
Contaminated wash and
rinse water from the
nine-stage washer.
Sediment from the
water treatment facility.
die-cast parts.
Install a metal recovery 8 bbl5 5
system (an ion-exchange
or electrodialysis system)
to recover and reuse zinc
phosphate from the nine-
stage washer. '
Recover solvent from the 3.794 gal 68
paint curing oven stacks
using a freon-refrigeration
system,
Construct a water recir- 855,135 gal 90
culating system in
conjunction with the on-
site treatment facility.
Install air curtains in the 79,715 gal 10
nine-stage washer to 13 bbl5' 8
reduce solution con-
tamination and loss.
Use a gas-fired dryer 138 bbl 85
to dry the solid waste
from the filter press before
shipping the waste off-site.
17,349
74,600
4.3
11,337
11,027
7,197
8,199
104,000
42,760
6,500
40,000
9.2
3.9
0.9
4.9
1 Primer/paint overspray 2Solvent 3Cleaning solvent 4Still bottoms 5Sediment
3
GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40256
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United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
BULK RATE
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EPA/600/S-92/020
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