1

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 That document has been superseded by the Facility Pollution Prevention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 manufactures commercial food service equipment. Raw

materials used by the plant include stainless steel, mild steel,

aluminum, and copper and brass. Operations performed in the

plant include cutting, forming, bending, welding, polishing, painting, and assembly. The team’s report, detailing findings and

recommendations, indicated that paint-related wastes are generated in large quantities and that significant cost savings

could be achieved by retrofitting the water curtain paint spray

booth to operate as a dry filter paint booth.

This Research Brief was developed by the principal investigators and EPA’s National Risk Management Research 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.

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 (Philadelphia, PA) 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

National Risk Management Research 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 pollution prevention opportunity 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 pollution

prevention.

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.

Pollution Prevention Assessment for a Manufacturer

of Food Service Equipment

ENVIRONMENTAL

RESEARCH BRIEF

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

and Gwen P. Looby**

 * Colorado State University, Department of Mechanical Engineering.

** University City Science Center, Philadelphia, PA.

United States

Environmental Protection

Agency

National Risk Management

Research Laboratory

Cincinnati, OH 45268

Research and Development EPA/600/S-95/026 September 1995
2

Methodology of Assessments

The pollution prevention opportunity 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 manufactures commercial food service equipment,

storage bins, cabinets, and other miscellaneous sheet metal

products. Sixty employees produce one-half million pounds of

stainless steel and painted steel products during approximately

2,200 operating hours annually.

Manufacturing Process

Specialty Sheet Metal Fabrication

Food service equipment, counter tops, case work, and other

products required on a job-shop basis are produced in the

custom shop area of the plant. Raw materials used include

stainless steel (primarily), mild steel, aluminum, and copper

and brass.

Stainless and mild steel arrive at the plant in sheets of precut

blanks that are trimmed to size using hydraulic shears. Operations performed include plasma cutting, forming, bending, custom welding, polishing, finishing, and assembly.

Ice Storage Equipment Fabrication

The other production activity at this plant is the fabrication of

ice storage equipment. Trimmed sheet metal received from the

shearing operation is cut, formed, welded, finished, prepared

for painting, painted, and insulated with a polyurethane foam.

An abbreviated process flow diagram depicting the production

operations of this plant is shown in Figure 1.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes.

• Scrap stainless steel is collected and sold to a scrap metal

dealer for reuse.

• A citrus-based cleaner is used instead of solvents in some

wipe-down cleaning operations.

• Most of the ice storage products are coated using powder

coating technology rather than conventional painting, thereby

reducing the generation of paint-related wastes.

• The nozzle of the foam insulation application system is

cleaned with ethylene glycol rather than methylene chloride.

Pollution Prevention Opportunities

The type of waste currently generated by the plant, the source

of the waste, the waste management method, the quantity of

the waste, and the waste management cost for each waste

stream identified are given in Table 1.

Table 2 shows the opportunities for pollution prevention that

the WMAC team recommended for the plant. The opportunity,

the type of waste, the possible waste reduction and associated

savings, and the implementation cost along with the simple

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 opportunities, 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 pollution prevention opportunity independently

and do not reflect duplication of savings that may result when

the opportunities are implemented in a package.

Additional Recommendations

In addition to the opportunities recommended and analyzed by

the WMAC team, two other measures were considered. These

measures were not analyzed completely because of projected

lengthy payback times. Since these approaches to pollution

prevention may, however, increase in attractiveness with changing conditions in the plant, they were brought to the plant’s

attention for future consideration.

• Install a solvent recovery unit to recover waste toluene

generated during parts cleaning and wipe-down in the painting area.

• Install an enclosed spray gun washer in order to reduce

solvent air emissions associated with paint gun cleaning.

This research brief summarizes a part of the work done under

Cooperative Agreement No. CR-819557 by the University City

Science Center under the sponsorship of the U. S. Environmental Protection Agency. The EPA Project Officer was Emma

Lou George.
3

Stainless Steel

And Other Metals

Shearing

Custom Shop

Ice Storage Equipment

Fabrication

- Plasma Cutting

- Forming

- Bending

- Welding

- Polishing

Fabrication

- Plasma Cutting

- Forming

- Bending

- Welding

- Polishing

- Finishing

Painting Preparation

Painting

Foaming

Assembly

Completed Products

Fabrication

Figure 1. Abbreviated process flow diagram for production of food service equipment.
4

Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

Waste Stream Generated Source of Waste Waste Management Method Generated (lb/yr) Management Cost ($/yr)

Scrap stainless steel Shearing operations Sold as scrap 112,500 not available

Evaporated mineral spirits Cleaning Evaporates to plant air 360 $1201

Evaporated lacquer thinner Cleaning Evaporates to plant air 4,290 1,8401

Spent alkaline cleaner Preparation of mild steel for painting Discharged to sewer as industrial wastewater 49,980 0

Rinse water Preparation of mild steel for painting Discharged to sewer as industrial wastewater 49,980 0

Spent phosphating solution Preparation of mild steel for painting Discharged to sewer as industrial wastewater 49,980 0

Waste toluene Cleaning of cabinets prior to painting Shipped offsite as hazardous waste; distilled for 1,060 9001

reuse or incinerated

Evaporated toluene Cleaning of cabinets prior to painting Evaporates to plant air 380 1301

Waste toluene Cleaning of small parts Shipped offsite as hazardous waste; distilled for 520 4601

reuse or incinerated

Evaporated citrus-based cleaner General cleaning in custom shop Evaporates to plant air 230 2201

Evaporated solvent from primer and thinner Painting operations Evaporates to plant air 490 501

Paint overspray Painting operations Captured in paint booth water curtain; shipped offsite 520 1,7901

with paint sludge (water) as hazardous waste; distilled

for reuse or incinerated

Paint sludge (water) Paint booth water curtain Shipped offsite as hazardous waste; distilled for reuse 3,3302 2,9402

or incinerated

Evaporated toluene Paint gun cleaning Evaporates to plant air 750 2601

1Includes lost raw material value.

2An additional 12,510 lb of paint sludge currently is stored onsite awaiting disposal.
5

Table 2. Summary of Recommended Pollution Prevention Opportunities

Annual Waste Reduction

Net Annual Implementation Simple

Pollution Prevention Opportunity Waste Stream Reduced Quantity (lb/yr) Percent Savings Cost Payback (yr)

Retrofit the currently used water curtain paint spray booth Paint sludge 3,330 100 $3,760 $ 2,000 0.5

to operate as a dry filter paint booth. Savings will result from

reductions in the generation and disposal of hazardous paintrelated material, labor costs for periodic paint booth cleaning,

and energy costs for operating the booth. Filters containing

paint overspray can be dried and disposed of as municipal

trash.

Replace the currently used conventional paint spray guns Evaporated solvent from 220 45 1,260 900 0.7

with high-volume low-pressure spray guns. Savings will primer and thinner`

result from reductions in the amount of paint and associ- Paint overspray 380 73

ated thinners that must be purchased and in the quantity

of waste paint-related material that must be disposed of.

Replace toluene used for cleaning small parts in the paint- Waste toluene from 520 100 280 670 2.4

ing area with an alternate, less toxic solvent. Waste re- cleaning of small parts

duction will result from reduced generation of spent

toluene and savings will result from a decrease in waste

disposal costs and a decrease in solvent purchases.

A small quantity of oil will be collected on filters; the oil

can be shipped to an oil recycler at little or no cost.
6

United States

Environmental Protection Agency

National Risk Management Research Laboratory (G-72)

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-95/026

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35