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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 manufacturers, Waste Minimization Assessment Centers (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). That document has been superseded by the Facility Pollution Prevention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 million per year. Special-purpose coatings such as chromate conversion, 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 investigators and EPA’s Risk Reduction Engineering Laboratory, Cincinnati, 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, Philadelphia, PA.

Introduction

The amount of 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 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 Reduction Engineering Laboratory, the Science Center has established 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 experience 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 minimization.

The potential benefits of the pilot project include minimization

of the amount of waste generated by manufacturers and reduction 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.

Waste Minimization Assessment for a Manufacturer

of Coated Parts

United States

Environmental Protection

Agency

Risk Reduction

Engineering Laboratory

Cincinnati, OH 45268

ENVIRONMENTAL

RESEARCH BRIEF

Research and Development EPA/600/S-94/014 September 1994

Harry W. Edwards*, Michael F. Kostrzewa*,

and Gwen P. Looby**

E AP

* Colorado State University, Department of Mechanical Engineering, Fort Collins,

CO

** University City Science Center, Philadelphia, PA
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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 procedures 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 technological and economic information is developed. Finally, a

confidential report that details the WMAC’s findings and recommendations (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 coatings.

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 coating, 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 application 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 dragout.

• 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 minimization opportunity, in most cases, results from the need for less

raw material and from reduced present and future costs associated 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 independently 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. Environmental Protection Agency. The EPA Project Officer was Emma

Lou George.
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Steel

parts from

customers

Aluminum

parts from

customers

• Alkaline cleaner

• Zinc phosphating

• Rinse

• Seal rinse

Chromate

conversion coating

• Alkaline cleaner

• Rinse

• Desmut

• Chromating

• Rinse

Painting

• Masking

• Coating application

• Oven cure

• Inspection, unmasking

Spent process

solutions and rinse

water discharged

to sewer

Zinc

phosphating

Evaporated

solvents

Waste solvent

and waste paint

to offsite incineration

Coated parts

returned to customers

Plastic

parts from

customers

Figure 1. Abbreviated process flow diagram.
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Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

Waste Generated Source of Waste Generated (lb) Waste Management Method Management Cost*

Cleaning, desmut, and coating solutions Chromate conversion line 7,500 Combined and sewered $1,030

Cleaning, coating, and sealing solutions Zinc phosphating line 8,500 Combined and sewered 2,890

Rinse water Chromate conversion and 24,800,000 Sewered 5,780

 zinc phosphating lines

Spent methyl ethyl ketone Paint line 1,700 Shipped offsite for incineration 1,300

Spent xylene Paint line 1,380 Shipped offsite for incineration 900

Spent toluene Paint line 1,850 Shipped offsite for incineration 1,240

Spent isopropyl alcohol Paint line 420 Shipped offsite for incineration 830

Spent methyl isobutyl ketone Paint line 1,700 Shipped offsite for incineration 1,640

Spent lacquer thinner Paint line cleanup 840 Shipped offsite for incineration 640

Paint sludge Paint line 2,200 Shipped offsite for incineration 2,440

Evaporated methyl ethyl ketone Paint line 2,330 Evaporates to plant air 870

Evaporated xylene Paint line 600 Evaporates to plant air 180

Evaporated lacquer thinner Paint line cleanup 2,420 Evaporates to plant air 900

Evaporated ethyl alcohol Paint line cleanup 70 Evaporates to plant air 110

Evaporated 1,1,1-trichloroethane Vapor degreasing 170 Evaporates to plant air 130

* Includes waste treatment, disposal, and handling costs and applicable raw material costs.
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BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-94/014