&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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