>A
                               United States
                               Environmental Protection
                               Agency
                                Risk Reduction Engineering
                                Laboratory
                                Cincinnati OH 45268
                               Research and Development
                                EPA/600/M-90/017 Dec. 1990
ENVIRONMENTAL
RESEARCH   BRIEF
           Waste Minimization Assessment for a Manufacturer of
                                 Printed  Plastic Bags

                              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
hazardous waste but who  lack the expertise to do so.
Waste Minimization Assessment Centers (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 printed plastic bags
for snack  foods—approximately 1.8 million Ib/yr. Plastic
stock is ink printed and oven cured. To make single-layer
bags, a heat seal process is used, and the bags are then
packaged and shipped. For certain products, a plastic or
metalized film is laminated  to the printed plastic film, the
rolls are slit to obtain individual bags, and the bags are
packaged and shipped. The team's report, detailing
findings and recommendations, indicated the most waste
was generated in the lamination process and  that the
greatest  savings could be obtained by installing  an
automatic adhesive/solvent mixing system to reduce (75%)
the waste from the unused metalized film adhesive/solvent
mixture.

This  Research Brief was  developed by the principal
investigators and EPA's  Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce key findings of an
 University City Science Center, Philadelphia, PA 19104
                 ongoing research project. For additional information please
                 contact the authors.

                 introduction

                 The amount of hazardous waste generated  by industrial
                 plants has become an increasingly costly  problem for
                 manufacturers and  an additional stress  on the
                 environment. One solution to the problem 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 generation  of
                 hazardous 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
                 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 hazardous 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 a gross annual  sales not  exceeding  $50  million,
                 employ no more than 500 persons, and lack inhouse
                 expertise in waste minimization.
                                                                          Printed on Recycled Paper

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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 procedures outlined in the EPA Waste Minimization
Opportunity Assessment Manual  (EPA/625/7-88/003, July
1988).  The WMAC staff locates the  sources of hazardous
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
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

The plant produces printed plastic  bags for snack foods.
The plant operates 6,240 hr/yr to produce approximately
1.8 million Ib of bags.

Manufacturing Process

This plant prints  designs onto plastic roll stock and then
forms  the plastic into bags for  snack  foods and other
consumer  products. The  raw  materials include
polypropylene  and metallic films,  inks,  adhesives,  and
solvents.  The  adhesives  include  clear  film adhesive,
metalized film adhesive, and thermostripping adhesive;  the
solvents are ethyl acetate, ink solvent, and thermostripping
solvent.

The following steps are involved in making the bags:

•   Ink printing of plastic stock followed by oven curing.
    Unused  and  contaminated  ink/solvent mixture  is
    collected and transferred to the onsite distillation unit.
    Waste  ink  resulting  from  run  color changes  is
    disposed of offsite as hazardous waste. Solvent vapor
    is  emitted directly to the outdoor atmosphere by three
    of the four curing ovens. In the remaining curing oven,
    50%  of the  vapor is  recycled to the oven and  the
    remaining is  ducted to an incinerator  outside of  the
    plant building.

•   Single-layer bag-making. A heat seal process is used,
    and then these bags are packaged and shipped.

•   For certain products, lamination to form multi-layered
    plastic rolls followed by oven  curing. A clear plastic or
    metalized film is  laminated to the printed plastic film,
    or a special kind of lamination  called thermostripping
    is  done. Unused  adhesive/solvent  mixture from  the
    metalized film application are disposed of offsite  as
    hazardous  waste. Half of the  stack gases from  the
    curing oven, which contain evaporated solvents,  are
    directed back into the oven. The remaining gases are
    ducted to the outside incinerator.

•   Slitting of laminated plastic rolls to obtain  individual
    bags. These bags are then packaged and shipped.

Existing Waste Management Practices

•   Recovery of ink-contaminated solvent using an onsite
    distillation unit. The recovered solvent is reused in the
    inking operation or is used for cleanup.  Ink  still
    bottoms are disposed of offsite as hazardous waste.

•   Incineration of oven stack vapor  in the outdoor gas-
    fired incinerator.

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 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 hazardous 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  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
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 completely
analyzed because of insufficient data or minimal  savings
as indicated below. They  were brought to  the plant's
attention  for  future reference,  however,  since  these
approaches to  waste  reduction  may  increase in
attractiveness with changing plant conditions.

•   Mix the  ink and solvent in a smaller container directly
    at the presses to reduce the generation of ink/solvent
    waste. Minimal savings are projected for this measure.

•   Possibly recover  solvent on the used cleanup rags
    through some type of  evaporation  process. This
    opportunity was not analyzed further because of a lack
    of detailed data and limited field experience with such
    systems.

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Table 1. Summary of Current Waste Generation
             Waste Generated
            Source of Waste
                                                                                   Annual Quantity
                                                                                     Generated
  Annual Waste
Management Cost
 Unused ink
 Evaporated ink solvent
 Unused metalized film adhesive/solvent
 mixture
 Evaporated adhesive solvents



 Spent Ink


 Spent solvent on rags
Ink presses.                                      60 gal
Ink that cannot be used because of
changes in run color is collected and
disposed of as hazardous waste.
Ink presses.                                   8,550 gal
Solvent evaporates in the curing ovens
associated with the ink presses. A portion
of the solvent is lost to the atmosphere.
The remainder is fed to the onsite
incinerator.
Laminator.                                     2,490 gal
Unused adhesive/solvent required for
metalized film application is discarded
daily, collected, and disposed of as
hazardous waste.
Laminator.                                    39,100 gal
So/vents in  the adftestVes evaporate in the
curing oven associated with the laminator.
The vapor is fed to the onsite incinerator.
Solvent recovery distillation unit. Ink still             195 gal
bottoms from the distillation unit are
disposed of as hazardous waste.
Equipment and plant cleanup. Soiled rags         7,000 Ib1
wetted with solvent are disposed in              1,850 gal3
municipal trash.
       $970
                                                                                                               720
      43,690
       3,280
       4,880
'flags
2 Plant personnel report no incremental cost associated with present disposal in municipal waste,
3 Solvent
Table 2. Summary of Recommended Waste Minimization Opportunities
Waste
Generated
Evaporated
solvents





Unused
metalized film
adhesive/
solvent
mixture

Spent solvent
on rags


Minimization Opportunity
Install a condensing system on
each of the oven stacks to
recover evaporated solvents.
Remove any water collected
along with the solvents in a
distillation unit. Reuse the
solvents
Install an automatic
adhesive/solvent mixing
system. The amount of unused
adhesive/solvent will be
reduced as will evaporation of
the solvent.
Use solvent as a cleaning
agent only for equipment. For
all other cleanup use a
nonhazardous detergent.
fviuuai wdait
Quantity
23,900 gal






1,860 gal





1,750 /to*
463 gal6


, ncuuouu,/ Nat Annual Implemenfatinn Payhrtr.k
Percent Savings Cost Years
50 $69,800' $ 63,800 0.9






75 75.9002 27,900 0.4





25 204 0 0



1 Total savings reduced by annual operating cost of the condensing systems and distillation unit.
2 Includes savings on raw materials.
3 Rags
4 Total savings reduced by the purchase price of the new detergent.
^ Solvent

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This research brief summarizes a part of the work done
under Cooperative Agreement No. CR-814903 by the                                                               j
University City Science Center under the sponsorship of                                                            I
the U.S. Environmental Protection Agency. The EPA
Project Officer was Brian A. Westfall.
  United States                  Center for Environmental Research
  Environmental Protection         Information
  Agency                       Cincinnati OH 45268


  Official Business
  Penalty for Private Use $300

  EPA/600/M-90/017
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