United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S-93/008 September 1993
&EPA ENVIRONMENTAL
RESEARCH BRIEF
Waste Minimization Assessment for a Manufacturer
of Product Carriers and Printed Labels
Marvin Fleischman*, 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 Louisville performed an
assessment at a plant manufacturing high density polyethylene
product carriers and printed polystyrene packaging labels. The
team's report, detailing findings and recommendations, indi-
cated the most waste was generated by the cleaning of printing
presses and printing plates. Several opportunities for minimiz-
ing solvent waste were recommended to the plant.
This Research Brief was developed by the principal investiga-
tors and EPA's Risk Reduction Engineering Laboratory (RREL),
Cincinnati, OH, to announce key findings of an ongoing re-
search 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 be-
come an increasingly costly problem for manufacturers and an
additional stress on the environment. One solution to the prob-
lem of hazardous 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
University of Louisville, Department of Chemical Engineering
University City Science Center, Philadelphia, PA 19104
inhouse expertise to do so. Under agreement with EPA's
RREL, the Science Center has established three WMACs.
This assessment was done by engineering faculty and stu-
dents at the University of Louisville's WMAC. The assessment
teams have considerable direct experience with process op-
erations 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 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.
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 support-
OyD Printed on Recycled Paper
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ing technological and economic information is developed. Fi-
nally, 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 manufactures printed polystyrene packaging labels
and high density polyethylene (HOPE) product carriers. Over
400 employees operate the plant 8,400 hr/yr to produce eight
billion labels and over 500 million product carriers each year.
Manufacturing Processes
The manufacturing processes used in this plant and the wastes
generated are described below.
Polystyrene Extrusion
The production of polystyrene labels begins with the extrusion
of bulk polystyrene into rolls of film. Both new polystyrene
pelletized stock and re-pelletized reground polystyrene mate-
rial are used, along with additives. The polystyrene is co-
extruded into foam.rolls consisting of two layers using Freon-
22' blowing agent to form cells in the inner layer. The ex-
truded film is then slit and rolled. Running trim is removed from
the film as it is rolled and is pneumatically conveyed to the
regrind area of the plant for recycle. The rolls are then sent to
the warehouse for curing prior to printing. Volatile emissions
from the extrusion process include the blowing agent and
residual impurities in the polystyrene (including styrene mono-
mer and ethyl benzene), which leave the plant through its
ventilation system.
Photopolymer Plate Production
Artwork for the label-printing plates is generated onsite or
received from the customer. The artwork is photographed and
the resulting negative is then used to sensitize an ultraviolet-
sensitive sheet of plate stock. The plate is then washed with n-
butanol/perchloroethylene solvent mixture, leaving a raised print-
ing surface on the plate. Damaged or obsolete plates are
disposed of with the general trash. Any silver-containing
photoprocessing wastes are collected and sent to the film
manufacturer for reclamation. Spent solvent mixture is sent to
the solvent recovery area. A portion of the solvent mixture
evaporates to the plant air.
Polystyrene Label Printing
As production is scheduled, the required roll stock is delivered
to the printing area from the warehouse. The required blends
of solvent-based inks are prepared using concentrated disper-
sions. Propylene glycol methyl ether (PM glycol ether) is added
to the mixtures for volume and viscosity adjustment
The ink is transported to the correct press station, a circulating
pump is attached to each ink bucket, and the ink is pumped to
the appropriate feed tray on the press,
The presses are washed down with a mixture of fresh ethyl
acetate and reclaimed solvent following printing runs. Spent
solvent is sent to the solvent recovery system. Fresh PM glycol
ether solvent is used to wash the printing plates.
A large quantity of propylene glycol methyl ether solvent evapo-
rates from the printing operation and is vented from the plant.
Ethyl acetate, which is also used during clean-up, also evapo-
rates to plant air. Soiled shop rags are cleaned by an outside
service and reused by the plant. Misprinted polystyrene is
reground and sold to a reclaimer at a discount.
Post-Printing Operations
The post-printing operations are product specific. Defective
labels are removed, labels are die-cut and slit, and rolls of
labels are shrink-wrapped. The labels are then transferred to
the warehouse to await shipping.
HOPE Extrusion
The processing of HDPE for use in product carriers proceeds
in a manner similar to that for the processing of polystyrene
film. Running trim from this line is also sent to the regrind area
for recycle.
HDPE Thermoforming
The HDPE roll material is delivered to the thermoforming line
where the carriers are formed, cut, and packaged. The finished
carriers are then transported to the warehouse to await ship-
ping.
Regrind
Waste material (polystyrene and HDPE) from various areas of
the plant is sent to the regrind area. The material is separated
by type and reground into flakes. The flakes are then repelletized
in preparation for reuse onsite or sale to brokers.
Polystyrene
LDPE/HDPE
Finished product to customers
Mention of trade names or commercial products does not constitute endorse-
ment or recommendation for use.
Figure 1. Abbreviated process flow diagram for label manufacturing.
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HOPE
Extrusion
Warehousing
Thermoforming
Figure 2.
Finished Product to Customers
Abbreviated process flow diagram for product-earner
manufacturing.
Solvent Recovery
Two large distillation units are operated by the plant to recover
spent solvent (ethyl acetate and PM glycol ether) from the
printing operation. The recovered solvent is reused in cleaning
the presses. A smaller distillation unit is used to recover sol-
vent from the photopolymer shop for reuse in plate preparation.
Abbreviated process flow diagrams for the two products manu-
factured are shown in Figures 1 and 2.
Existing Waste Management Practices
This plant has already taken the following steps to manage and
minimize its wastes:
All extrusion wastes that have not been inked are
reground and reworked onsite.
A minimum amount of waste is generated by the ink
formulation process. Off- specification inks and sur-
plus inks are reworked.
Ink runs are scheduled to allow light-to-dark transi-
tions in the printing trays. The trays on the presses
are dedicated to specific colors as much as possible.
Wash-up solvent is recovered onsite for reuse.
The number of different solvents used by the plant for
ink formulation has been reduced.
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 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 other possibilities for waste minimiza-
tion were evaluated by the assessment team. These measures
were not analyzed completely because of insufficient data or
minimal savings. They were brought to the manufacturer's
attention for future reference, however, since these approaches
to waste reduction may increase in attractiveness with chang-
ing plant conditions.
Recover the Freon blowing agent used in conjunc-
tion with polystyrene extrusion. A large capital cost
would be required for implementation of this opportu-
nity. Alternative blowing technologies are being inves-
tigated by the plant.
Develop a better use for the waste inked-polystyrene.
Convert to water-based inks to reduce or eliminate
solvent emissions and waste management costs.
Recover stack gases from the curing ovens.
This research 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. She can be reached at:
Pollution Prevention Research Branch, MS 466
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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Table 1. Summary of Current Waste Generation
Waste Generated
Source of Waste
Annual Quantity
Generated
Annual Waste
Management Cost
Freonru-22
(blowing agent)
Residual volatiles
Perchloroethylene
n-butanol
Propylene glycol
methyl ether
Ethyl acetate
Soiled shop rags
Misprinted polystyrene
Wash solvent still
bottoms (ethyl
acetate/propylene
glycol methyl ether)
Plate washing
solvent still bottoms
(perchloroethylene/
n-butanol)
Purge waste from
wash solvent recovery.
General trash
Polystyrene extrusion. The Freon 579,000 Ib
blowing agent is used during the formation
of the polystyrene film. The unretained
blowing agent is vented from the plant.
Polystyrene extrusion. The residual volatile 21,610 Ib
impurities present in the polystyrene are
vented from the plant during the extrusion process.
Photopolymer plate preparation. A portion of 6,000 Ib
the perchloroethylene used in the cleaning
of printing plates evaporates to plant air.
Photopolymer plate preparation. A 1,500lb
portion of the n-butanol used in the cleaning
of printing plates evaporates to plant air.
Label printing. A portion of the propylene 728,540 Ib
glycol methyl-ether that is used for thinning
ink and cleaning the presses and
plates evaporates to plant air.
Label printing. A portion of the ethyl 146,000 Ib
acetate that is used for cleaning the presses
evaporates to plant air.
Label printing. The rags used in the 35,000 pieces
cleaning operations are laundered off site and
returned to the plant.
Label printing. Misprinted labels are 4,000,000 Ib
reground and sold to a broker at a discount.
Solvent recovery. Still bottoms from the recovery 18,770 gal
process for the wash solvent are shipped
offsite as hazardous waste.
Solvent recovery. Still bottoms from 385 gal
the recovery process for plate washing
solvent are shipped offsite as hazardous waste.
Solvent recovery. The entire contents of the 9,500 gal
wash solvent recovery system are purged
periodically as a result of maintenance problems.
The waste is shipped offsite as hazardous waste.
Various processes. 6,000 yd3
$ 550,0501
1,8601
5701
393,4001
62,0501
N/A
-1,208,9502
154,130
3,160
39,0201
18,750
'Includes cost of raw material.
2Revenue received.
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Table 2. Summary of Recommended Waste Minimization Opportunities
Waste Generated
Purge waste from
wash solvent
recovery
Minimization Opportunity
Install a membrane pervapor-
ation system to remove water
from the spent wash solvent
prior to solvent recovery in
the distillation units. Tlte
removal of water will alleviate
the corrosion problems which
have led to the need tc purge
the system periodically.
Annual Waste Reduction
Quantity Percent
9, 500 gal 100
Net Annual
Savings
$ 44,0601
Implementation
Cost
$ 123,700
Payback
Years
2.8
Wash solvent still
bottoms (ethyl
acetate/propylene
glycol methyl ether)
Wash solvent (ethyl
acetate/propylene
glycol methyl ether)
Propylene glycol
methyl ether
Wash solvent (ethyl
acetate/propylene
glycol methyl ether)
Install a secondary solvent 15,020 gal
recovery system to recover
reusable solvent from the
still bottoms. The proposed
system consists of a solvent
recovery still equipped with a
vacuum recovery attachment.
Dispose of the secondary still
bottoms cake as a delisted
nonhazardous waste in order
to reduce disposal costs.
Install a fractional distillation 0
unit to recover PM glycol ether
and ethyl acetate as essentially
pure components. Reuse the
ethyl acetate for washing the
presses and reuse the PM
glycol ether in formulating the
inks. No waste reduction will
result from this measure, but
significant cost savings will
be realized.
Install a cooling system to chill 31,440 Ib
the ink/solvent mixture in the
press station trays to reduce
the evaporative losses of PM
glycol ether.
Install hand-held rinse spray 0
guns on each of the rinse
stations on the printing
presses to reduce the
amount of solvent needed
for rinsing.
80
88,710
1.3
71.300L2
350,000
4.9
16,9801
67,1301
11,200
770
0.7
0.01
'Includes savings on raw materials.
2Total savings reduced by annual operating cost of system.
fcu.8. GOVERNMENT HUNTING OffTICC: I*H - T9M71/INM
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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-93/008
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
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