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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 That document has been superseded by the Facility Pollution Prevention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 manufactures wooden kitchen and bathroom cabinets.

Components purchased from vendors are prepared for production through cutting, sanding, and routing operations. Stain,

sealer, and top-coat are applied in separate spray booths. After

the final coating, the components are dried and assembled.

The assessment team’s report, detailing findings and recommendations, indicated that paint sludge from the spray booth

water curtains is generated in a large amount and that significant cost savings could be achieved by dewatering the sludge

before it is shipped offsite for disposal and reusing the water.

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

Wooden Cabinets

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-95/024 September 1995
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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 wooden kitchen and bathroom cabinets. It operates 2,200 hr/yr to produce about 150,000 cabinets

annually.

Manufacturing Process

Most of the cabinet doors and components used in producing

the cabinets are received pre-cut from outside vendors. Other

components are sent to a preparation area where they are cut,

sanded, and edged. Components are then stored until needed

on the painting line.

Employees use a printout of the day’s scheduled production to

send the correct components to the painting area in the proper

order and quantity. First, the parts are sent by conveyor to a

staining booth that uses air-assisted airless spray guns that

rotate and coat the components on one side as they are

passed through the booth. After exiting the booth the parts are

flipped over and sent through a second staining booth where

they are stained on the other side. Overspray is captured by a

water curtain, and solvents are allowed to evaporate.

Next the components travel to another spray booth for sealer

application. The sealer booth uses air-assisted airless guns to

spray one side of the components. Again, overspray is captured by a water curtain. The parts then travel to a final

painting booth for top-coat application. Overspray is collected

in the same manner as in the other booths.

After the final coating, the components are dried in a large kiln

and then sent to the assembly line. The parts are glued and

stapled into finished cabinets, and drawers are assembled in a

similar manner. The face boards are added as the cabinets

move down the line. The cabinet doors are pre-hinged and

then fastened to the cabinets. Assembled cabinets are inspected and shipped.

An abbreviated process flow diagram is shown in Figure 1.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes.

• Soap is used instead of lacquer thinner for cleaning the steel

conveyor bands on the painting lines. Prior to the change to

soap cleaning, approximately one drum of lacquer thinner

was used each day for cleaning the bands.

• Used wooden pallets are recycled offsite when possible.

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 annual 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, in most cases, the economic savings of

the minimization opportunities result from reductions in raw

material and costs associated with hazardous 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 that pollution prevention opportunity alone and do not

reflect duplication of savings that would 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 insufficient data, implementation difficulty, or a projected lengthy

payback. Since one or more of 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.

• Replace the water curtains in the paint booths with a dry filter

bed for collection of overspray.

• Install air-assisted airless fine finish paint guns and paint line

heaters to reduce the amount of paint overspray generated.

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.
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Pre-Cut Cabinet Doors

and Other Components

Preparation

- Cutting

- Sanding

- Routing

Stain

Application

Sealer

Application

Top Coat

Application

Drying

Assembly

Inspection

Completed Cabinets

to Customers

Figure 1. Abbreviated process flow diagram for wooden cabinet manufacturers.
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BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

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-95/024

Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

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

Paint sludge Water curtain in sealer and top-coat Shipped offsite for disposal as 130,000 $101,000

spray lines hazardous waste

Evaporated lacquer thinner Stain, sealer, and top-coat lines Evaporates to plant air 19,030 10,0101

Evaporated paint solvents Spray booths Evaporate to plant air 236,000 0

Waste lacquer thinner Cleaning of equipment Shipped offsite for disposal as 38,900 33,2001

hazardous waste

Miscellaneous solid waste Various operations Shipped offsite to municipal landfill 364,000 23,600

1Includes lost raw material value.

Table 2. Summary of Recommended Pollution Prevention Opportunities

Annual Waste Reduction

Net Annual Implementation Simple

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

Install a purification system to reduce the Paint sludge 47,000 36 $45,070 $9,600 0.2

water content of the paint sludge generated through treatment of the wastewater

from the water curtains in the sealer and

top-coat spray booths. Implementation

of this opportunity will lead to a reduced

volume of hazardous waste shipped

offsite.

Capture the lacquer thinner used for line Evaporated lacquer 9,520 50 3,880 500 0.1

cleaning in the paint spray booths and thinner

reuse it. Current practice is to use the

thinner once and spray it into the water

curtain from which it evaporates.

Segregate waste cardboard from other Miscellaneous 0 —- 5,670 4,600 0.8

solid waste, bale it, and sell it to a card- solid waste

board recycler. The resulting reduction

in volume of solid waste will lead to

lower landfill costs. No waste reduction

will result from this opportunity.