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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 That document has been superseded by the Facility Pollution Prevention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 the

University of Tennessee performed an assessment at a plant

that prewashes denim jeans prior to retail sale. Predyed jeans

are received from other facilities and washed. An abrasive

material is used in some of the wash loads. Some of the jeans

are processed in tumblers in order to give the jeans a faded

look. After processing, the jeans are dried, inspected, mended,

pressed, packaged, and shipped. The assessment team’s report, detailing findings and recommendations, indicated that

the waste generated in the greatest quantity is wastewater

from the washers and tumblers and that the greatest cost

savings could be realized by installing an onsite wastewater

treatment plant.

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.

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

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 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 Prewashed Jeans

United States

Environmental Protection

Agency

Risk Reduction

Engineering Laboratory

Cincinnati, OH 45268

ENVIRONMENTAL

RESEARCH BRIEF

Research and Development EPA/600/S-94/006 September 1994

Richard J. Jendrucko*, Thomas N. Coleman*,

and Gwen P. Looby**

* University of Tennessee, Department of Engineering Science and Mechanics.

** University City Science Center, Philadelphia, PA.

E AP
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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 prewashes predyed denim jeans for wear modification prior to retail sale. Over 7 million pairs of jeans are

processed annually by this plant.

Manufacturing Process

The following steps are involved in processing the jeans:

• Predyed jeans are received from other facilities and sorted

into lots.

• Jeans are washed to strip dye and starches from the material.

An abrasive is used in 10% of the washing loads. Some of the

jeans go directly to tumblers.

• Some of the washed jeans and other jeans not previously

washed are processed in tumblers where they are physically

and chemically abraded with pumice and enzymes to give the

jeans a faded and “worn” look. Other jeans go directly to

drying after washing. Jeans are rewashed after tumbling.

• The garments are dried, inspected, and mended as needed.

• Garments are graded as first, second, or third quality.

• Garments are steam pressed, labels are applied, and the

prewashed jeans are packaged and shipped to distribution

centers.

An abbreviated process flow diagram for producing prewashed

jeans is shown in Figure 1.

Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes:

• Containers in which the jeans are received are disassembled

and shipped back to the supplier for reuse.

• Pumice of an acceptable size is reused.

Waste Minimization 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 treatment and disposal cost for each

waste stream identified 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 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 the need for less raw

material and from reduced present and future 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 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.

Jeans

Unpacking

and

sorting

Washing

Pumice

(for 10% of

loads)

Pumice,

enzymes Tumbling

Drying

Sorting

Inspection,

mending,

grading

Pressing

Tagging

Auditing

Finished jeans

packaged and

shipped

Figure 1. Abbreviated process flow diagram for producing prewashed

jeans.
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Table 1. Summary of Current Waste Generation

Waste Stream Annual Quantity Annual Waste

Generated Source of Waste Waste Management Method Generated (lb) Management Cost1

Wastewater Washers Filtered; sewered 533,869,230 $210,170

Wastewater Tumblers Filtered; sewered 53,387,090 20,980

Evaporated water Dryers and other sources Evaporates to plant air 39,425,000 13,110

Pumice and lint Removed from wastewater 1,137,500 105,440

 using hydrosieve and shaker

 screen Shipped to municipal landfill

Pumice grit Settles out of wastewater in 349,500 37,580

 holding pit Shipped to special landfill

General plant waste Various processes Compacted; shipped to 1,650,000 73,760

 municipal landfill

1 Includes waste treatment, disposal, and handling costs and applicable raw material costs.

Table 2. Summary of Recommended Waste Minimization Opportunities

Annual Waste Reduction

Waste Stream Net Annual Implementation Simple

Minimization Opportunity Reduced Quantity (lb) Percent Savings Cost Payback (yr)

Install an onsite wastewater Wastewater 513,250,000 95 $350,0001 $1,570,000 4.5

 treatment plant to treat spent from washers

 water from the washing and Wastewater 50,760 95

 tumbling operations. Reuse from tumblers

 treated water. A nonhazardous

 sludge will be generated if this

 opportunity is implemented.

Reuse rinse waters used in the Wastewater 284,856,000 53 95,480 23,260 0.2

 washing operations during the from washers

 next washing cycle.

Install a screen over the dump- Pumice and lint 140,000 40 23,690 3,300 0.1

 ster that is used to collect pumice

 from the hydrosieve and the

 shaker screen in order to recover

 additional pumice stones for reuse.

Install plastic shrouds to reduce Pumice and lint 140,000 40 18,6901 3,000 0.2

 pumice lost in the space between

 the housings and drums in the

 tumblers.

Meter the wastewater leaving the Wastewater — — 7,125 5,140 0.7

 plant in order to reduce sewer

 charges. Currently, the plant’s

 sewer charges are based on the

 amount of water purchased not on

 the amount of water sewered.

 A significant amount of water is

 absorbed by the jeans in the

 washing process and subsequently

 removed by drying. In addition other

 water losses from spills and steam

 pressing occur.

1 Total annual savings have been reduced by the annual operating cost required for implementation.
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United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-94/006

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35