©EPA
United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/M-91/044 Oct. 1991
ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a Manufacturer of
Refurbished Railcar Bearing Assemblies
F. William Kirsch 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. Waste Minimization Assessment Cen-
ters (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). The WMAC team at the University of Tennessee
performed an assessment at a plant that rebuilds railcar
bearing assemblies — approximately 163,200 bearing com-
ponents per year. Bearings are disassembled, washed, then
inspected. "Premium" bearings, those still within specifica-
tions, are reassembled with new grease and bearing seals,
packaged, and shipped. Nonpremium bearings are buffed,'
rinsed in hot water, and then chrome plated to build up the
bearing surfaces. After chroming, the parts are rinsed, baked,
and allowed to air cool. Cooled bearings are reassembled with
new grease and seals, then packaged and shipped. The
team's report, detailing findings and recommendations, indi-
cated that the majority of waste was generated during the
railcar bearing cleaning operation and that the greatest sav-
ings could be obtained by instigating onsfte wastewater treat-
ment and recirculating recovered water to reduce (90%) water
consumption in the railcar bearing cleaning operation.
•University City Science Center, Philadelphia, PA 19104.
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 the authors.
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 is to reduce or eliminate the waste af 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 formation of waste but lack the
inhouse 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 atthe 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. Toqualifyforthe assessment, each client must fall within
Standard Industrial Classification Code 20-39, have gross
^£9 Printed on Recycled Paper
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annual sales not exceeding $50 million, employ no more than
500 persons, and lack inhouse expertise in waste minimization.
The potential benefits of the pilot project include minimization of
the amount of waste generated by manufacturers, reduced
waste treatment and disposal costs for participating plants,
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
/lss0ssmenfManua/(EPA/625/7-88/003.July1988).TheWMAC
staff locates the sources of waste in the plant and identifies the
current disposal or treatment methods and their associated
cosis.Theythen 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 refurbishes railcar bearing assemblies for outside
customers. Its 120 employees produce approximately 163,000
bearing assemblies annually.
Manufacturing Processes
This plant rebuilds railcar bearing assemblies. Raw materials
Include bearing lubricant (grease), new bearing seals, chrome
plating constituents (chromic acid and sulfuric acid), alkaline
detergent, and rust preventative.
The following steps are involved in refurbishing the railcar
bearings:
• Bearings, which are shipped to the plant from outside
customers, are disassembled and parts are separated.
Lubricant is removed by manually wiping off the bearing
parts, placing the parts in a centrifugation device, and
wiping off any residual lubricant. Discarded grease is dis-
posed of offslte as npnhazardous waste. Spent seals are
disposed of in municipal waste.
• Bearing parts are then washed in an alkaline-detergent
solution and rinsed. Contaminated water is shipped offsite
for disposal as a nonhazardous waste. Next, the bearings
are inspected to ensure proper surface thickness along the
cone surface. Those bearings that meet specifications and
are characterized as "premium" are reassembled with new
grease and bearing seals while the bearings that are
identified as "nonpremium" are transferred to the chrome
shop for electroplating buildup of the inside surfaces of the
bearings. In the chrome shop, the bearing surfaces are
buffed then rinsed in hot water. The parts are then racked
and dipped in the chromic acid plating tanks. After chrom-
ing, the parts are rinsed in hot and then cold water. Chromic
acid sludge that results from chrome shop operations is
shipped offs'rte as hazardous waste. Parts are then baked
in a dry-off oven, cooled, and reassembled with new grease
and seals.
Existing Waste Management Practices
• Trivalent chrome that is produced during chroming opera-
tions is regenerated into hexavalent chrome for reuse,
thereby greatly reducing the amount of waste generated
and the cost of raw materials and waste removal.
• The plant has sealed all but the sanitary sewer drains and
ships offsite all nonhazardous waste water generated from
bearing cleaning operations to avoid interaction with the
liquid municipal waste treatment agency (POTW).
• Plant personnel reduce residual drag-out from the chrom-
ing operations by individually rinsing each part and rack
above the chrome and rinse tanks, thus reducing the
concentrations of plating metals in the chromic acid sludge
that is shipped offsite as a hazardous waste. This additional
rinsing operation also supplies make-up water to the chrome
plating baths to compensate for evaporative losses.
Waste Minimization Opportunities
The type of waste currently generated by the plant, the source
of the waste, the quantity of the waste, and the annual treatment
and disposal costs are given in Table 1.
Table 2 shows the opportunities for waste minimization that the
WMACteam recommended forthe plant. The type of waste, the
minimization opportunity, 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 quantifi-
able by this study include a wide variety of possible future costs
related to changing emissions standards, liability, and employee
health. It should also 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 would result when the oppor-
tunities 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.
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Table 1. Summary of Current Waste Generation
Waste Generated
Source of Waste
Annual Quantity
Generated
Annual Waste
Management Cost
Spent grease
Spent bearing seals
Contaminated wash and
rinse water
Chromic acid sludge
Cleaning of railcar bearings. Grease that is 2,750 gal
removed from the bearing parts is disposed of
offsite.
Disassembly of railcar bearings. Spent bearing 326,400 units
' seals are disposed of in municipal trash.
Cleaning of railcar bearings. The wash and 249,975 gal
rinse water used in cleaning the bearings is
shipped offsite as nonhazardous waste.
Chroming processes. Chrome sludge that 660 gal
results from the rinsing and plating operations in
chrome shop is shipped offsite as hazardous
waste.
$13,200
3,150
50,050
33,530
Table 2. Summary of Recommended Waste Minimization Opportunities
... _ _, J Annual Waste Reduction Net Implementation Payback
Waste Stream Reduced Minimization Opportunity Quantity Percent Annual Savings Cost Years
Contaminated wash
and rinse water
Chromic acid sludge
Install a closed wastewater 244,480 gal
treatment system and
redrculate tine water for
bearing cleaning
Install a chromic acid
recovery system. It is
estimated that 90% of the
chromic acid can be purified
and reused in the chroming
165 gal
98
25
$32,170
15,120
$41,880
42.700
-1.3
2.8
•trV.S. GOVERNMENT PRINTING OFFICE: 1991 - S48-028/4007«
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EPA/600/M-91/044
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