&EPA
United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S-92/017 June 1992
ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a
Manufacturer of Military Furniture
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 manufacturing military furnitureap-
proximately 12,000 units/yr. Wood and formica are laminated
together via glue curing and then undergo woodworking opera-
tions including cutting, drilling, and routing. Finished boards are
either packaged and shipped or transported to assembly. Metal
stock is cleaned with solvent and then undergoes various
metalworking operations. Metal pieces are partially assembled,
painted, then either packaged and shipped or transferred to
assembly before being packaged and shipped. The team's
report, detailing findings and recommendations, indicated that
the majority of waste was generated during the painting opera-
tions and that the greatest savings could be obtained by
installing an electrostatic powder coating system to completely
eliminate paint solvent evaporation, paint solids waste, and
paint-laden air filters.
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 document 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 prob-
lem of waste 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 formation 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 $50 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, 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.
GyD Printed on Recycled Paper
University City Science Center, Philadelphia, PA 19104
-------
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 Afanoa/(EPA/625/7-88/003, July 1988). The WMAC
staff locates the sources of waste in the plant and identifies 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. Figure 1 shows a
simplified process flow diagram of the operation of the plant.
Plant Background
The plant manufactures military-specification furniture for use
in military barracks. Ninety employees operate the plant 2,080
hr/yrto produce approximately 12,000 units of furniture annu-
ally.
Manufacturing Process
The plant produces wooden, wood with steel frame, and steel
furniture. Raw materials include heavy-density particle board,
steel frame, rolls and strips of sheet steel, formica, and as-
sorted hardware. !
j
Unit operations performed in processing wood include the
following:
Raw wood and formica are glued together to form a
laminate. Several laminations are then positioned in a
press for glue curing. Next, the boards undergo vari-
ous woodworking operations including cutting, drilling,
and routing. Boards are either transferred to assembly
or directly packaged and shipped. ;
Metal processing involves the following unit operations:
Metal stock is cleaned by immersion in a toluene dip
tank. Waste from this process includes evaporated ,
toluene and sludge containing toluene, grease, and
dirt, which is pumped from the bottom of the tank.
After cleaning, the metal undergoes various metal-
working operations including cutting, punching, fold-
Wood/Formica
Laminating
Woodworking
Metal Stock
Dipped in
Toluene
2*.
^
Solvent
Evaporation
and Sludge
Generation
V
Partial
Assembly
Wastewater
5-Stage
Cleaning
Dip
Painting
Paint Waste
and
Wastewater
£
Spray
Painting
Assembly
Package and Ship
Flgun 1. Simplified process flow diagram.
-------
ing, and welding. Pieces are partially assembled, then
transferred to one of two spray-paint lines or a dip-
paint line.
In the spray-paint line, parts undergo a five-stage
cleaning in preparation for spray-painting. The first
stage is an alkaline-wash tank held at 110°F. That
wash stage is followed by a rinse tank. Next, parts are
sprayed with an iron phosphate solution. The fourth
stage is a rinse tank, fn the final stage, parts are
sprayed with a rust preventive. After cleaning, the
parts are conveyed first through a dry-off oven and
then through the spray-painting process.
In spray-painting, paint is applied to the parts with
hand-held spray guns. The paint booths are equipped
with continuously recirculating water curtains to en-
trap paint overspray. Entrapped paint solids and waste-
water are dumped to a holding tank periodically. Air
filters which are used in two of the four booths to
collect overspray are also disposed of periodically.
After painting, the parts are conveyed through a dry-
off oven and undergo further assembly.
Small metal parts are dip-painted, allowed to air dry,
and then transferred to the assembly area.
Assembly and packaging.
Existing Waste Management Practices
A steam-cleaning operation to eliminate the five-stage
cleaning of some metal parts is being investigated.
The use of dip-painting has been minimized.
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 man-
agement costs are given in Table 1.
Table 2 shows the opportunities for waste minimization that the
WMAC team recommended for the 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, 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 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 imple-
menting each waste minimization opportunity independently
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 additional measures were considered.
These measures were not analyzed completely because of
insufficient data or minimal savings as indicated below. They
were brought to the plant's attention for future reference, how-
ever, since these approaches to waste reduction may increase
in attractiveness with changing plant conditions.
If the spray paint process is not replaced as recom-
mended in the WMOs, there are two other possible
improvements to be considered. A state-of-the-art dip
paint line with safeguards to minimize paint dripping
on floors could be installed to replace the paint lines.
Another alternative is to switch from solvent-based to
water-based paints.
Use air-tight spray gun cleaning tanks to reduce evapo-
rative losses of toluene.
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
Annual Annual
Quantity Waste Manage-
Waste Generated
Toluene sludge
Evaporated toluene
Evaporated paint solvent
Paint-laden air filters
Source of Waste
Toluene-dip tank for cleaning of metal stock. The sludge, which contains
toluene, grease, and dirt, is hauled offsite as a hazardous waste.
Toluene-dip tank for cleaning of metal stock.
Spray-paint booths.
Spray-paint booths.
Generated
715 gal
172 gal
915 gal
832 filters
3,390 gal paint
ment Cost
$8,230
0'
0>
1,020
Toluene sludge
Evaporated toluene
Paint solids
Cleaning of paint guns. The sludge, which contains toluene and paint, 55 gal 630
is hauled offsite as a hazardous waste.
Cleaning of paint guns. 44 gal 0'
Holding tanks which receive wastewater from the five-stage cleaner 7,515 gal 3,750
and the painting operation.
' According to plant personnel, there are no waste management costs associated with evaporation of solvents.
U.S. Government Printing Office: 1992 648-080/60013
-------
Tsb!a2.
Summary of Recommended Waste Minimization Opportunities
Waste
Stream
Reduced
Evaporated
paint solvent
Paint laden air
filters
Evaporated
toluono
Paint solids
Toluene sludge
Evaporated
toluene
Minimization Opportunity
Install an electrostatic powder coating
system to replace the paint-spray and dip-
paint lines. The proposed system will
provide more even coating of parts and
easy collection and reuse of overspray
powder.
Protect the clean metal stock from
environmental dirt to eliminate the need
for subsequent cleaning In the toluene-dip
tank.
Annual Waste
Quantity
915 gal
832 filters
3,390 gal paint2
44 gal
7,515 gal
715 gal
172 gal
Reduction
Percent
100
100
100
100
100
100
100
Net Imple-
Annual ! mentation
Savings Cost
$49,770'
8,40V
$145,880
3,800
Pay-
back
Years
2.9
0.5
Evaporated Repair the lid of the toluene-dip tank to
toluene reduce evaporative losses. Institute a
program to keep lid closed whenever
possible.
86 gal
50
180'
100 0.5
Paint solids
Re-install the existing electrostatic 2,210 gal 29 39.SSO'-3
spray paint system in building 4 and
Install an electrostatic spray paint
system in building 3. The electrostatic
spray paint systems will be considerably
more efficient than the current spray-
paint systems.
66,900 1.7
* Paint associated with the spent air filters.
3 Total savings have been reduced by the operating cost of the proposed system.
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
i BULK RATE
PQSTAGE & FEES PAID
EPA PERMIT NO. G-35
r
Official Business
Penalty for Private Use $300
EPA/600/S-92/017
!
------- |