HAZARDOUS WASTE MINIMIZATION: PART 111
Waste Minimization in the
Paint and Allied Products Industry
Gregory A. Lorton
Jacobs Engineering Group
Pasadena, California
plied dry onto the object. The object is
then baked, causing the resins to melt
and/or polymerize. Upon cooling, a
tough, durable coating results. Radiation-cured coatings are applied to the
object, which is then irradiated with
ultraviolet light or electron beams,
causing the coatings to polymerize and
harden. Two-part catalyzed paints are
mixed together immediately before being applied to the object. These paints
then polymerize, forming a hard, dry
surface. None of these coating systems
relies on the evaporation of solvent or
water.
This paper looks at waste minimization practices available to the paint and
coatings industry. The paper begins with an introduction to the industry
and a description of the products. The steps involved in the manufacture of
paints and coatings are then described. The paper then identifies the wastes
generated. Source reduction and recycling techniques are the predominant
means o f minimizing waste in this industry. Equipment cleaning wastes are
the largest category o f wastes, and the paper concentrates on equipment and
techniques available \ to reduce or eliminate these wastes. Techniques are
described to reduce the other wastes from manufacturing operations. The
paper concludes with a discussion o f changing industry product trends and
the effect that these trends will have on the generation o f waste.
Paint Production Processes
The paints and allied products industry consists of firms that manufacture
paints, varnishes, lacquers, enamels
and shellacs, putties, wood fillers and
sealers, paint and varnish removers,
paint brush cleaners, and allied paint
products. The manufacture of pigments, resins, printing inks, adhesives
and sealants, or artists’ materials is not
included in this category. In 1986,sales
in the paints and allied products industry were just over $11billion.’
The paint manufacturing industry
terids to concentrate in poplilatioii ceiiters because of high transportation
costs. Nearly half of all paint manufacturing plants are located in California,
New York, New Jersey, Illinois, and
Ohio. Two-thirds of all plants are located ih ten states. Table I presents the
size of paint manufacturing companies
as a function of the number of employees.
product coatings, and special purpose
coatings. Table I1 presents the quantities and sales volume, as well as the
major uses of coatings within these categories.
Paint products are also categorized
by the vehicle, or carrier (solvent-based
or water-based). The vehicle, solvent or
water, evaporates after the paint has
been applied to the surface of the object being painted. The paint cures as
the evaporation takes place.
Nonvolatile coatings are categorized
according io the method of curing.
These include powder coatings, radiation-cured coatings, and two-part catalyzed paints. Powder coatings consist
of a finely divided powder of thermoplastic or thermosetting resins mixed
with pigments. Powder coatings are ap-
A typical plant produces both solvent-based and water-based paints.
The processes for both types of paints
are generally similar, although the ingredients vary. Water-based paints are
typically composed of water, pigments,
resins, extenders (to extend drying
time), ammonia, dispersant, antifoam
additives, polyvinyl alcohol emulsion,
and a preservative. Solvent-based
paints are typically composed of a solvent, pigments, extenders, resins, plasticizers, and drying oils. Figure 1 is a
simpiified flow diagram of the paint
manufacturing steps.
The manufacture of water-based
paints begins by mixing water, ammonia, and dispersant together in a mixing tank. Ground pigment and extenders are then added to this mixture.
Table I. Company size distribution.a
Products
1-19
Number of employees per facility
100+
2049
50-99
~
Paint industry products are broadly
categorized according to their use, The
categories are architectural coatings,
~
Number of companies
Number of emdovees
819
6.400
331
10.500
171
11.800
120
25.400
Total
~
1,441
54.100
~~
Source: U.S. Department of Commerce, Bureau of Census, 1982 Census of Manufacturers, Washington, D.C., 1985.
a
Copyright 1988-APCA
A 3 3
.-
^^
.
*
.
In some manufacturing planta, a single high-speed mixer is used in place of
the separate grinding and mixing steps.
Paint batch sizes typically range from
10to 500 gallons in smallplants and for
specialty paints, to lo00 to 3000 gallons
in large facilities.
Table 11. Distribution of paint products by use, quantity, and sales.a
Percent
Architectural coatings
Interior, solvent-based
Interior, water-based
Exterior,solvent-based
Exterior, water-based
Lacquers
Other and not specified
Product coatings
Metal Containers
Automotive
Machinery
Sheet, Strip, and Coil
Metal Furniture
Other
Special purpose coatings
High performance
maintenance
Automotive and
machinery refinishing
Traffic paint
Other
Production (1986)
(million gallondyear)
Sales (1986)
($ billion)
525
4.5
11
43
16
23
2
5
Wastes from Paint Manufacturing
371
3.9
250
2.7
The predominant wastes from paint
manufacturing facilities include:
0
Equipment cleaning wastes, including:
-waste rinsewater
-waste solvent
-paint sludge from cleaning operations
0
Off-spec paint
0
Obsolete paints and returned
paints
0
Empty raw material packages,
bags, and containers
Pigment dusts from air pollution
control equipment
0
Air emissions
0
Paint filter bags and cartridges
0
Accidental spills and discharges
Of these wastes, equipment cleaning
wastes are by far the largest, accounting for over 80 percent of the industry’s
wastes.2 Since paint manufacturing is
essentially a blending operation and
not a chemical conversion operation,
the compounds present in the waste are
the same compounds that are present
in the input materials. Paint manufacturing facilities typically segregate
their wastes to the extent required by
the waste disposal contractor. With increasing treatment and disposal costs,
and impending land disposal bans,
19
16
6
6
5
48
31
29
14
26
a Sources:D. Webber, “Coatingindustry headed for a record year,” Chemical and
Engineering News, Val. 62, No. 40, p. 51; and J. M. Winton, “Coatings ’87,”
Chemical Week,Vol. 141, No. 15, p. 30.
When mixing is complete, the material
is then ground in a mill and transferred
to an agitated mix tank. In the agitated
mix tank, resin and plasticizers are
added to the mixture, followed by the
preservative and antifoaming agent,
and then the polyvinyl acetate emulsion. Finally, water is added as a thinner to reach the desired consistency. At
this point, the paint is filtered to remove any undispersed pigment and
then loaded into cans. The cans are labeled, packed into shipping cartons,
and moved into storage.
The steps in the manufacture of solvent-based paints are similar to waterbased paints. Solvent-based paints are
made by first mixing ground pigments,
resins, and extenders in a high speed
mixer. Solvents and plasticizers are
also added during this operation. The
batch is then transferred to a mixing
tank, and tints and solvent thinner are
added. Once the desired consistency is
reached, the paint is filtered, packaged,
and loaded into shipping containers.
Solvent or Water
Resins
Additives
Solvent 01Water
Additives
BATCHING
I
1
!3
I
f
L
Products into
Packages
Figure 1.
Steps in the paint manufacturing process.
April 1988
Volume 38,NO.4
423
WASTE MANAGEMENT
Fresh solvcni make-up
Solvent still botlom
o blending (dF rework)
Flgure 2.
Recycling and reusing cleaning solvent.
paint companies are turning to waste
minimization, which includes source
reduction and recycling.
Waste Minimization
Waste minimization provides companies with the following incentives:
Reduced operating costs for:
-waste treatment and disposal
-raw materials and cleaning solutions/solvents
Improved regulatory compliance
Reduced environmental liability
and workplace safety liability
Also, successful waste minimization
will often result in an improved image
within the eyes of the community and
the employees.
Minimizing Equipment Cleaning Wastes
Equipment for making solventbased paints is often cleaned with solvents. The resulting waste consists of a
mixture of solvent and paint. Water or
caustic solutions are used to clean
equipment for making water-based
paints. Caustic cleaning solutions are
generally preferable, since they can
more easily remove dried paint from
the equipment surfaces. Two methods
of caustic cleaning are generally employed. In one method, the solution is
prepared in a holding tank, pumped
through the equipment to be cleaned,
and then returned to the holding tank.
In the second method, the caustic solution is made up in the mixing tank to be
cleaned and allowed to soak the tank
until the tank is clean.
Source Reduction of Cleaning
Wastes. Equipment cleaning wastes
can be reduced by reducing the frequency of required cleaning and/or reducing the amount of cleaning solvent
or solution used for cleaning. The toxicity of equipment cleaning wastes can
be reduced by using less toxic or nontoxic cleaning materials.
Wastes from equipment cleaning can
be reduced by reducing the frequency
of equipment cleaning. Scheduling for
long production runs, or scheduling
batches from light colors to dark
can reduce the need for
need for caustic
increases the yield of paint and also
reduces the amount of solvent or solution required to subsequently clean the
pipes. Inert gas is used to push the pigs
through the pipes, since air might increase the rate a t which the paint dries
in the pipes. The pig launcher and
catcher must be carefully designed t o
prevent accidental spills, sprays, and
injuries.2
High pressure water spray systems
have been designed to limit the amount
of water used in cleaning water-based
paint manufacturing equipment.
These systems can reduce cleaning water use by 80 to 90 percent. Also, high
pressure water sprays can remove partially dried paint, thereby reducing the
need for caustic cleaning.5 Mix tanks
used for making solvent-based paints
equipment to manufacturing a single
solution necessary to clean the tank.
type of paint. In this way, the equip- 1
ment is cleaned only occasionally, rathRecycling and Reuse of Cleaning
er than after each batch. In a California
Wastes. Cleaning wastes can usuallv be
plant, tanks that are dedicated to a sinreused in any of the following ways:
gle product are washed with solvent
collected and used in the next comthat remains in the tank and becomes
patible batch of paint as part of the
formulation.
part of the formulation of the next
batch.3
collected and distilled for reuse eiAny technique t h a t reduces t h e
ther onsite or offsite.
amount of paint adhering to the surcollected and reused over and over
faces of the process equipment and
for equipment cleaning until it is
connecting pipes will reduce t h e
too contaminated for further reuse.
Allowing the solids to settle out of the
amount of solvent, caustic solution, or
solvent can extend the solvent’s life for
water needed to clean the equipment.
cleaning. Cleaning solvent wastes can
Manual scraping with spatulas can inbe distilled to recover solvent for reuse.
crease the yield of product and reduce
Caustic solution wastes are typically
the quantity of waste paint. This, in
neutralized and then disposed of. The
turn, reduces the amount of cleaning
reuse of cleaning solution or solvent
solvent or solution required to clean
the tank. In larger mix tanks, rubber
can be increased by removing the accuwipers can be installed to scrape off the
mulated paint sludge. This can be acpaint that clings to the tank walls. New
complished by decantation, filtration,
or centrifugation. Simply allowing
mix tanks are available with automatic
enough time for the paint sludge to setwall scraper^.^ It has been recommendtle will allow the solvent to be decanted
ed that tanks lined with non-stick suroff and reused.
faces, such as TeflonTM
(Du Pont tradeSegregating, collecting, and reusing
mark), be used to reduce the amount of
solvents can significantly reduce the
paint clinging to the tank walls.2 By
generation of waste solvents. In one
designing mix tanks with length-to-diNorth Carolina company, waste solameter ratios of 1:1, the surface area to
vent was reduced from 25,000 gallons
volume of the tank can be minimized.
in 1981to 400 gallons in 1982 by schedThis reduces the amount of paint adhering to the sides of the tank for a
uling compatible paint batches and
-given batch size.
segregating, collecting, and reusing
The piping connecting the various
Icleaning solvents from different color
mixing tanks and the loading hoppers
batches. However, a second North Carretains paint after batches are comolina company tried this practice and
pleted. Plastic or foam “pigs” have
then abandoned it, because it proved
been used to remove paint from these
too complicated. This second company
pipes. The pig is forced through the
produced a wide variety of high-quality
specialty products. The high cost of
pipe, pushing paint ahead of it that had
been clinging to the pipe walls. This
raw materials and the risk of contami-
-
3
nating an entire product batch outweighed the savings in virgin solvent
costs and waste solvent disposal.6 The
attractiveness of solvent reuse and
waste segregation varies from company
to company. However, as treatment
and disposal costs continue to rise,
these practices will become more and
more attractive.
Figures 2 and 3 are simplified flow
diagrams of cleaning systems for solvent-based paints and water-based
paints, respectively. These systems reduce waste by reusing cleaning solvent
or solution as much as possible. In the
solvent system, a periodic bleed of the
reused solvent is taken and sent to the
solvent still. The volatile solvent is reclaimed from the still and returned for
reuse. The still bottoms are blended
into paint product. In the rinse water
and alkaline solution system, a periodic
bleed is taken and sent to a settling
tank. When the bleed i s alkaline
sludge, pH adjustment is necessary.
The clarified solution is discharged to
the plant's wastewater treatment unit.
The sludge from the settling tank is
reworked into product. A paint manufacturer in California operates systems
similar to these. The sludge from the
rinse water and alkaline cleaning solution system is reworked with fresh materials to produce a beige-colored water-based paint. The still bottoms from
the solvent cleaning system is reworked
with fresh materials to produce a primer p r ~ d u c t . ~
Cleaning Material Substitution.
Noncaustic alkaline cleaning solutions
are available that can be used in place
of caustic cleaning solutions. These solutions tend to be more stable than
caustic solutions, less toxic, and do not
present the disposal problems that
caustic solutions do. At one facility, the
frequency of cleaning solution replacement has been reduced by a factor of
two by replacing caustic solutions with
alkaline cleaner^.^
Water washing can be used to clean
equipment producing water-based
paints. When water is used to wash the
equipment, considerable quantities of
wastewater is generated. However, this
wastewater can be collected and reused
in subsequent compatible paint batches as part of the formulation, or can be
reused for equipment cleaning until it
loses its cleaning ability. Although water washing may be less effective than
caustic solution washing, it eliminates
the toxicity problems associated with
caustic.
Good Operating Practicesto Minimize
Other Wastes
Good operating practices offer the
primary means for dealing with many
of the other wastes from paint manufacturing operations. Good operating
practices are defined as organizational
or administrative methods of influencing the work patterns of employees so
as to promote their participation in
waste minimization activities. Careful
attention to production and maintenance operations will reduce waste
generation resulting from spills or the
production of off-spec paints. Making
employees aware of the impact of hazardous wastes on a company's costs, as
well as the impact on the environment,
can help to reinforce this. Employee
training is another important good operating practice.
Most off-spec paint is generated by
small shops t h a t produce specialty
paints. Since the production costs for
specialty paints are typically high,
most off-spec paints are reworked into
marketable products. There is a clear
economic incentive for this. However,
the costs of reworking off-spec paints
are avoided if better trained and supervised operators and quality control are
p i n , water reuse Imp,
Rinse solution reuse loop
*
I
I
Make-up solution
Auraline Cleaning
Equipment
*
I
Equipment
10 tK clcancd
i
Waler Rinsing
Equipment
f-
Mike-up water
<
Acid
(for pH adjustment)
Sepdrdtor overflow
10 WdSleWdlr trC.ItrIIWl
Settled solids Io
blending (ds rework)
Figure 3.
Recycling and reuslng rinse water and alkaline cleaning solution.
April 1988
Volume 38,No. 4
reinforced so that the generation of offspec products is avoided in the first
place.
Obsolete paint products and customer returns can be blended into new
batches of paint. Obsolete products result from changes in customer demand,
new superior products, and expired
shelf life. Careful production planning
and inventory control can reduce obsolescence resulting from expired shelf
life. Marketing policies, such as discounting older paints, can also reduce
the amount of obsolete products.
A variety of good operating practices
are available for minimizing waste. Soliciting employees' suggestions for
ways to minimize waste often works
since the employees understand the
process operation. This can also make
it easier to implement waste minimization plans, since the employees are taking part in the planning. Incentives, rewards, and bonuses can be used to support a waste minimization program. In
large facilities where cost center accounting is used, consider apportioning
waste management costs to the departments or cost centers that generate the
waste.
Plant Automation
The intent of plant automation is to
avoid operational accidents and improve production efficiency. The effect
is to reduce waste in much the same
way as good operating practices. The
use of automation also reduces operating and maintenance labor costs. Examples of this include programmable
controllers and automatic batching. As
the costs of plant automation equipment decrease, the use of automation
in paint manufacturing facilities will
increase.
Minlmizing Empty Bag, Package, and
Container Wastes
Pigments may contain hazardous
compounds. The bag used for packaging dry pigments will typically contain
several ounces of pigment after they
have been emptied. As such, these bags
become hazardous waste themselves
unless they are cleaned. Cleaning and
drying the bag allows it to be disposed
of as nonhazardous waste. Ordering
pigments in slurry or paste form eliminates the problem of waste bags or
packages. Empty containers of liquid
raw materials that contain hazardous
compounds (such as solvents, resins, or
'fungicides) are typically cleaned or recycled back to the original raw material
manufacturer or to a local drum recycler. This avoids the cost of disposing
of the containers. Used cans that con425
.
’.
.
‘WASTE MANAGEMENT
tained non-hazardous containers can
be sold to metal recyclers.
Water-soluble bags and packages
have been developed for water-based
paint pigments and for toxic additives,
such as bactericides. These bags will
dissolve in the paint, thus eliminating
the disposal problems with the bags.
However, the use of water-soluble bags
does not lend itself to high-quality
paints designed to give smooth finishes.
input Material Substitution
Some additives, solvents, and pigments are hazardous materials, and
thus render waste paint as hazardous
when the paint is discarded. Lead and
chrome pigments are well-known for
their toxicity. Similarly, solvents render solvent-based paints as hazardous
because of their flammability and/or
toxicity. In addition to pigments and
solvents, other additives are occasionally used that cause waste paint to be
hazardous. For example, mercurybased fungicides and bactericides are
used to prevent paints from deteriorating. The presence of these compounds
in an otherwise nonhazardous paint
will render the waste paint hazardous.
The substitution of nonhazardous
additives for hazardous ones is taking
place to some extent in the industry.
However, this substitution is hampered, since many of the substitute additives are less effective than the original materials. Other hazardous compounds t h a t are now undergoing
scrutiny are tributyltin, used in marine
paints, and methylenedianiline, used
-in making urethane coatings. As the
costs of waste disposal and the regulation of hazardous materials increases,
the incentives to find acceptable substitutes will increase.
Some paint pigments are available in
slurry or paste form. By using pigments
in these forms, rather than powders,
the need for air pollution equipment to
control pigment dusts can be reduced
or eliminated. This, in turn, reduces or
eliminates the generation of pigment
dust wastes.
Waste Paint Filters
Cartridge filters are commonly used
to remove large particles of pigment
from paints before packaging. Bag filters or fine mesh metal screen filters
are preferable to cartridge filters from
a waste point of view, since used cartridge filters retain substantially more
paint. Bag or screen filters are more
easily cleaned, leading to reuse of the
filter or disposal as a nonhazardous
waste.
Wastes from Spill Cleanup
Wastes resulting from accidental
spills can be reduced by recovering as
much of the spilled materials as practical. A California paint manufacturer
sends scooped up water-based paint
spills to its water treatment unit and
sends solvent-based spills to its solvent
recovery unit.3 If possible, the recovered material should be blended into
another batch to reduce the amount of
1M
64
Roduction
Volume
(Millions of
Dry Gallons)
4c
2c
a
19ai
Flgure 4. Production trends In coating systems.
1983
1993
waste. After scooping up as much of the
spilled material as possible, the remaining spill should be cleaned up with
dry absorbent. On the other hand,
cleaning up a spill with large quantities
of solvents, alkaline solutions, or water
should be avoided. Of course, wastes
from the cleanup of spills can be minimized by preventing spills in the first
place.
Trends in Product Substitution
The Clean Air Act and the Occupational Safety and Health Act were both
passed in 1970. These acts have been
largely responsible for the major shift
in paint products from solvent-based
products and toxic materials to waterbased products and nontoxic materials.
The switch from toxic heavy metal pigments, such as lead and chrome pigments, to less toxic or nontoxic materials has resulted from toxic materials
regulations, as well as a general public
desire to use less toxic paints. Air pollution regulations are responsible for the
switch from volatile solvent-based
products to water-based products and
solvent-based products with lower volativity. The markets for powder coatings and radiation-cured coatings are
also benefitting from the need to use
paints with low volatility. Figure 4 illustrates the shift in paint industry
products between 1983 and 1993.
Pigment Substitution
The paint industry has eliminated
the use of lead pigments to a large extent. The toxicity of lead-based paints
is well known, and these paints are no
longer available for general consumer
use. However, there still is a market for
red lead primers. Red lead pigments
are excellent as industrial primers, and
there are few substitutes in some applications. However, red lead primers represent only a small fraction of the output of most plants. With the increasing
regulation of lead compounds as toxic
materials, the market for lead-based
paint is expected to continue to decrease.’
Chrome-based paints are no longer
available for general consumer use.
Chrome yellow produces a bright color
and is now used mainly in traffic paint
(for example, lines on streets and parking lots). The current alternatives are
yellow organic.+igments, which are
generally more expensive, and yellow
iron oxide, which is not as bright. The
replacement of chrome yellow pigment
is impeded by governmental regulations requiring the use of these pigments in traffic paint.
Lead-based and chrome-based pig-
ments generally produce a more durable paint. Also, these pigments produce
desirable colors. The extent to which
these pigments are replaced by less
hazardous substitutes is a function of
both environmental regulations and
consumer demand for these products.
Reducing Air Emissions
The federal Clean Air Act and state
air emission laws have had a profound
effect on paint and coating products.
For example, in California, the EPA
has implemented requirements for solvent content in paints. Since September 1987, all nonflat architectural
paints must contain less than 250
grams of volatile organic compounds
(VOCs) per liter of paint. In some
cases, technical difficulties in formulating compliant products have resulted in delay in making these changes.
For example, alkyd gloss architectural
paints containing less than 380 g/L of
VOCs have been plagued by yellowing
problems and poor application and
drying characteristics.’ The ultimate
result of these regulations is increased
consumer demand for products with
high-solids (low solvent) paints, powder coatings, and water-based substitutes.
The use of solvents is generally decreasing in light of the air quality environmental regulations. The production
of conventional solvent-based coatings
has dropped from about 100 million
dry gallons in 1983 to 65 million dry
gallons in 1987. It is expected to drop to
40 million dry gallons by 1993. On the
other hand, production of the newer
high-solids solvent-based coatings has
jumped from 18 million dry gallons in
1983 to 35 million in 1987, and is expected to grow to 35 million dry gallons
in 1993.
Powder coatings contain little or no
solvents in their formulation. These
coatings are sprayed on dry, usually
with electrostatic spray equipment.
The coated part is then baked, forming
a polymeric coating on the surface of
the part. Powder coatings are now finding increasing applications, including
use in the automotive industry.’
Radiation-cured coatings have little
or no volatile solvents in their formulation. These coatings are cured in the
presence of either ultraviolet light
(W-cured paints) or high-energy electron beams (EB-cured paints). These
coating techniques do not require high
temperatures to cure the coatings and,
therefore, are especially useful on heatsensitive materials, such as paper,
wood, or plastics. Two-part catalyzed
paints also avoid the use of solvents
and, therefore, are finding increasing
April 1988
Volume 38,No. 4
applications in place of solvent-based
paints.
The industry is feeling pressure from
alternative products, such as prefinished interior wallboard, vinyl siding
and laminates, wallpaper, plastic panels, and glass. For example, plastic panels are now used increasingly on new
us. cars.1
Conclusion
Environmental and health issues
have had a major impact on the paint
manufacturing industry since the early
1970s. The industry is seeing substantial pressure from environmental regulators and consumers to change the formulation of paint products. In particular, the paint industry has significantly
reduced its use of toxic heavy metal
pigments and is gradually shifting from
solvent-based coatings to water-based
coatings, powder coatings, and radiation-cured coatings.
Although environmental and safety
issues have a major impact on the formulation of paints and coatings, customer preferences and requirements
are also very important. The customer’s preference for a durable finish
may warrant the continued use of hazardous components. Similarly, military
requirements dictate the use of certain
coatings that give high performance in
harsh environments. I n many instances, paint companies are facing
strong counteracting pressures to provide paints and coatings that are compliant with governmental regulations,
on one hand, and meet the customers’
needs on the other hand.
Waste minimization is making significant inroads into paint manufacturing plants. Since equipment cleaning operations are the largest source of
waste in the industry, source reduction
and recycling techniques will be important in the industry’s efforts to further
reduce wastes. Because of the increasing costs of waste treatment and disposal, most companies see attractive
economics in waste minimization. The
future will see continuing efforts and
developments to minimize waste from
paint manufacturing operations.
fornia Department of Health Services,
Sacramento, CA, 1987.
4. G. Weismantel, S. Guggilam, “Mixing
and size reduction,” Chemical Engineering 9 2 13 (1985).
5. “Development Document for Proposed
Effluent Limitation Guidelines, New
Source Performance Standards, and Pretreatment Standards for the Paint Formulating Point Source Category,” EPA440-1-79-049b,
US. Environmental Protection Agency, Office of Water and
Waste Management, Washington, DC,
1979.
6. J. Kohl, P. Moses, B.Triplett, “Managing and Recycling Solvents: North Carolina Practices, Facilities, and Regulations,” North Carolina State University,
Raleigh, NC, 1984.
References
1. J. M. Winton, “Coatings ’87,”Chemical
Week 141: 30 (!987).
2. Waste Minamlzataon Issues and Options, Volume 2, Appendix B, “Process
Studies,” US.Environmental Protection
Agency, Office of Solid Waste and Emergency Response, Washington, DC, Oct6ber 1986,pages B8-1to B8-24.
3. Waste Audit Study: Paint Manufacturing Industry, Jacobs Engineerin Group
Inc., Alternative Technology .lection,
Toxic Substances Control Divlsion, Cali-
Gregory A. Lorton is a senior
chemical engineer and project manager for the Hazardous and Toxic
Materials Division of Jacobs Engineering Group Inc., 251 S. Lake Avenue, Pasadena, CA 91101.This paper
was submitted for peer review February 1, 1988; the revised manuscript
was received February 23,1988.
427