United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S-94/006 September 1994
ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a Manufacturer
of Prewashed Jeans
Richard J. Jendrucko*, Thomas N. Coleman*,
and Gwen P. Looby**
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 manufactur-
ers Waste Minimization Assessment Centers (WMACs) were
established at selected universities, and procedures were
adapted from the EPA Waste Minimization Opportunity As-
sessment Manual (EPA/625/7-88/003, July 1988). That docu-
ment has been superseded by the Facility Pollution Prevention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 re-
port, 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 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 University City Science Center.
* University of Tennessee, Department of Engineering Science and Mechanics.
"University City Science Center, Philadelphia, PA.
Introduction
The amount of waste generated by industrial plants has be-
come 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 manu-
facturing 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 minimiza-
tion.
The potential benefits of the pilot project include minimization
of the amount of waste generated by manufacturers and re-
duction 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.
-------
Methodology of Assessments
The waste minimization assessments require several site visits
to each client served. In general, the WMACs follow the proce-
dures 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 tech-
nological and economic information is developed. Finally, a
confidential report that details the WMAC's findings and recom-
mendations (including cost savings, implementation costs, and
payback times) is prepared for each client.
Plant Background
This plant prewashes predyed denim jeans for wear modifica-
tion 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.
Jeans
Pumice,
enzymes
Pumice
(for 10% of
loads)
Finished jeans
packaged and
shipped
Figure 1. Abbreviated process flow diagram for producing prewashed
jeans.
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 pos-
sible 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 indepen-
dently 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. Environmen-
tal Protection Agency. The EPA Project Officer was Emma
Lou George.
-------
Table 1. Summary of Current Waste Generation
Waste Stream
Generated Source of Waste
Wastewater Washers
Wastewater Tumblers
Evaporated water Dryers and other sources
Pumice and lint Removed from wastewater
using hydrosieve and shaker
screen
Pumice grit Settles out of wastewater in
holding pit
General plant waste Various processes
1 Includes waste treatment, disposal, and handling costs a
Table 2. Summary of Recommended Waste Minimization i
Waste Stream
Minimization Opportunity Reduced
Install an onsite wastewater Wastewater
treatment plant to treat spent from washers
water from the washing and Wastewater
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
washing operations during the from washers
Waste Management Method
Filtered; sewered
Filtered; sewered
Evaporates to plant air
Shipped to municipal landfill
Shipped to special landfill
Compacted; shipped to
municipal landfill
nd applicable raw material costs.
Opportunities
Annual Waste Reduction
Quantity (Ib) Percent
513,250,000 95
50,760 95
284,856,000 53
Annual Quantity Annual Waste
Generated (Ib) Management Cost1
533,869,230 $210,170
53,387,090 20,980
39,425,000 13,110
1,137,500 105,440
349,500 37,580
1,650,000 73,760
Net Annual Implementation Simple
Savings Cost Payback (yr)
$350,0001 $1,570,000 4.5
95,480 23,260 0.2
next washing cycle.
Install a screen over the dump- Pumice and lint 140,000 40
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
pumice lost in the space between
the housings and drums in the
tumblers.
23,690
18.6901
3,300
3,000
0.1
0.2
Meter the wastewater leaving the Wastewater
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.
7,125
5,140
0.7
1 Total annual savings have been reduced by the annual operating cost required for implementation.
-------
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/S-94/006
------- |