&EPA
United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S-92/028 Sept. 1992
ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment: for a
Manufacturer of Industrial Coalings
Marvin Fleischman and Dermont J. Collins",
F. William Kirsch and J. Clifford Maginn, Jr."
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 Louisville performed an
assessment at a plant manufacturing industrial coatings —
approximately 2,700,000 gal/yr. The products are diversified,
being made in batches of varying size to meet customer speci-
fications. Pigments are milled as needed, and batches are
prepared by controlled mixing of solvents, resins, pigments or
dyes, and additives. The products are packaged in small con-
tainers, drums or*tanker trucks, or held in bulk storage tanks.
The team's report, detailing findings and recommendations,
indicated that most waste occurred as solvent loss by evapo-
ration and as residual solvent in emptied containers, and that
the greatest savings could be obtained by fitting batch tanks
with covers and submerged-filling tubes to reduce vapor losses
and storing solvent drums on an incline to reduce residual
solvent remaining in drums.
This Research Brief was developed by the principal investiga-
tors and EPA's Risk Reduction Engineering Laboratory, Cin-
cinnati, 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 Louisville, Department of Chemical Engineering
" 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 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
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 at the University of Louisville's
WMAC. The assessment teams have considerable direct ex-
perience 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 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 experience1 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 pro-
066 Printed on Recycled Paper
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cedures outlined in the EPA Waste Minimization Opportunity
Asssssment 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 rec-
ommendations (including cost savings, implementation costs,
and payback times) is prepared for each client.
Plant Background
The plant produces industrial coatings including stains, var-
nishes, and pigmented products. It operates 2,000 hr/yr to
produce approximately 2,700,000 gallons.
Manufacturing Process
This plant produces lacquer and varnishes; solvent-based and
water-based pigmented metal, wood, and plastic finishes; and
stains. The raw materials include resins, fillers, milling pastes,
pigments, dyes, sealers, nitrocellulose, and solvents. Solvents
used are methyl ethyl ketone, methyl isobutyl ketone, toluene,
xylene, mineral spirits, and alcohol.
The coatings are made in batches. The following steps are
involved:
• Tint pastes are prepared by grinding pigments with solvent
in ball mills and sand mills. The mills are cleaned with a
solvent-resin mixture to be used in the batch.
• Other raw materials for the batch are charged to a mixing
tank.
• The batch is mixed, and the tints are added to adjust the
color to specifications.
• The batch is filtered to remove large particles and dirt and
packaged in designated containers.
• The mixing tank is cleaned to prepare for the next batch.
An abbreviated process flow diagram is shown in Figure 1.
Existing Waste Management Practices
This plant already has taken the following steps to manage and
minimize its wastes:
• The plant uses offsite solvent reclamation, purchasing the
recovered solvent for use in cleaning equipment. Off-spec
and obsolete products are reworked into saleable prod-
ucts.
• A still Is used to recover spent wash solvent onsite.
• A trial lid is under test on batch tanks to reduce evapora-
tion losses and avoid dust loss when charging pigments.
• A sweep-blade mixer with attached squeegees is used to
minimize the amount of solvent needed for cleaning the.
batch tank after mixing high-viscosity materials.
• The final solvent charge used to expel the last remaining
tint paste from a milling machine is incorporated into the
product formulation and not disposed of as spent solvent.
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 times are given in the table. The quantities of hazard-
ous 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 should also 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 would
result when the opportunities are implemented in a package.
Additional Recommendations
In addition to the opportunities recommended .and analyzed by
the WMAC team, several additional measures were consid-
ered. These measures were not analyzed completely because
of insufficient data, implementation difficulty, or a projected
lengthy payback as indicated below. Since one or more of
these approaches to waste reduction may, however, increase
in attractiveness with changing conditions in the plant, they
were brought to the plant's attention for future consideration.
• Use a commercial alkaline cleaner instead of aqueous
caustic to clean process materials buildup from the floor.
Because the alkaline cleaner solutions are more effective,
a 50% reduction in the volume of cleaning waste is ex-
pected.
• Use the same alkaline cleaner instead of solvent to clean
up small spills that occur in daily operation.
• Dispose of collected pigment dust through a waste ex-
change. Pigment dust is now disposed of in a landfill and
is regulated as a hazardous waste.
• Use dedicated drip pans for particular raw materials in the
drum storage area, so collected material can be used in
product batches. At present the collected materials are
combined and disposed of as spent solvent.
• Make repeated use of wash solvent to reduce the amount
of solvent that must be purchased or reclaimed. Such
multiple use would require separation of solids present (by
decanting, filtering or centrifuging). At present, wash sol-
vent is used only twice.
• Implement procedures for complete discharge of material
from drums. This would result in additionaf charges for
labor or equipment.
• Recover solvent vapors now lost as fugitive and stack
emissions. This would require installation of equipment,
possibly at the point of emission of individual solvents.
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.
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Solvents
Raw
Materials
Lacquers, Paints,
Stains to Customers
Figure 1. Abbreviated process flow diagram.
Table 1. Summary of Current Waste Generation
Waste Generated
Source of Waste
Annual Quantity
Generated
Annual Waste
Management Cost
Pigment dust
Residual pigment in bags
Sludge and still bottoms
Solvent vapors
Residual solvents in containers
Drum leakage
Spent filter cartridges
Discarded bags and
spent filter media
Used staging pails
from prebatching
Pigment dust from process dust
collectors, bag breakage, and
sweepings is disposed of as
hazardous waste.
Empty bags with residual pigment
are disposed of as landfill.
Sludge and bottoms from
distillation of spent cleaning
solvent are disposed of in a fuels
or incineration program.
Volatile solvents are lost by
evaporation from mixing tanks and
from pigment mills operated at
140 "C or higher.
Solvents are lost in discarded or
recycled containers.
Drum leakage is collected and
combined with spent wash solvent
for distillation recovery by a
recycler.
Filter cartridges are used once and
disposed of as landfill.
Spent filter units are dried and
disposed of with empty pigment bags
as landfill.
Used pails are disposed of with
nonhazardous trash as landfill.
6,000 Ib
44,200 Ib
13,250 gal
27,518 gal
19,018 gal
9,1W gal
8,840 pcs
Unknown
48,620 pcs
$39,600
44,200
33,532
68,797
63,710
30,540
54,785
680
104,039
•fru.3. GOVERNMENT PMNTING OFFICE: IttM - 550-067/80154
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Table 2. Summary of Recommended Waste Minimization Options Identified
Waste Generated
Used staging pails
from prebatching
Used staging pails
from prebatching
Solvent vapors
Minimization Opportunity
Use a solvent spray washer
to clean the pails for
reuse instead of
discarding them.
The used pails can be
taken by a metal scrap
recycleratno charge.
Install lids on coating
Annual Waste Reduction
Quantity Percent
39,000 pcs
48,620 pcs
26,053 gal
80
100
95
Net
Annual Savings
$71,330
13,584
65,000
Implementation
Costs
$53,320
0
300
Payback
Years
0.5
0
0.0
Spent cartridge filters
Residual pigment
In bags
Solvent vapors
batch tanks to reduce
solvent vapor losses.
Replace disposable 8,840 pcs 100 51,887
cartridge filters with
reusable stainless steel
filters.
Shake or scrap the bags 33,165 Ib 75 28,100
for more complete
discharge of the pigment.
Modify process tanks for 4,655 gal 50 11,638
submerged-filling (through
a dip tube) to reduce
vapor loss.
6,640
3,202
0.1
0.3
Residual solvent
In drums
Incline solvent drums to
reduce the residual heel
of solvent.
4,559 gal 25 15,270
794 0.1
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-92/028
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