United States
                         Environmental Protection
            Risk Reduction
            Engineering Laboratory
            Cincinnati OH 45268
                         Research and Development
            EPA/600/S-92/020 May 1992
                         RESEARCH   BRIEF
               Waste Minimization Assessment for a Manufacturer of
                              Motor Vehicle Exterior Mirrors

                               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 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.

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

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-

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

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

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

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

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

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.
1 Primer/paint overspray  2Solvent  3Cleaning solvent  4Still bottoms   5Sediment

                                                                                   GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40256

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