&EHV
United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-123 Aug. 1981
Project Summary
Resource Recovery from
Plastic and Glass Wastes
Tom Archer and Jon Huls
As ona objective of the Resource
Conservation and Recovery Act, a
research program was initiated to
assess and evaluate the state-of-the
art for recovery of glass and plastics
from solid wastes. Currently, labor-
intensive source separation of glass
and plastics predominates, but me-
chanical and thermal recovery will
achieve greater importance in the
years ahead. Where data were available,
these technologies were discussed in
terms of technical, economic, and
environmental aspects, and obstacles
to recycling. Past and present research
efforts were identified, and research
needs to enhance recovery of resources
were addressed.
This Project Summary was devel-
oped by EPA's Municipal Environ-
mental Research Laboratory, Cincin-
nati, OH, to announce key findings of
the research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Plastic Manufacturing and the
Plastic Industry
Plastics is a generic term describing
strong, durable, light, easy to fabricate,
fairly inexpensive materials derived
from petrochemical feedstock. Plastics
are available in more than 40 families of
material types with a broad range of
performance characteristics (1). Plastics
are a rapidly increasing segment of the
economy, and new and variable uses
and markets make industry characteri-
zation difficult.
All plastics are either thermosetting
or thermoplastic. Thermosetting plastics
are set into permanent shape by the
application of heat and pressure, and on
reheating, they cannot be reshaped.
Thermosets account for more than 20
percent of the total U.S. polymer pro-
duction, and they are often used for
durable goods such as counter tops, pot
handles, knobs, and highly engineered
applications. They do not significantly
add to the municipal solid waste stream
(1).
Thermoplastics soften upon reheating
and harden upon cooling. Ease of use of
thermoplastics, plus specific resin char-
acteristics enhance their use. Thermo-
plastics are often found in the municipal
solid waste stream (1), and they account
for approximately 80 percent of polymer
production (2).
Plastic manufacturing is a diversified
and complex operation. From the raw
material input to the final consumer
product, the various operations within
the plastic industry are integrated into
various segments. Integration of opera-
tions within the plastic industry is
extensive. Thus one company can be a
resin producer, compounder, and fabri-
cator, and a manufacturer/packager
can sometimes operate as fabricator
and converter. As a plastic product is
made, starting from the resin, it normally
passes through manufacturing facilities
that progressively become smaller in
size and more dispersed geographically.
Glass Manufacturing and Glass
Industry
Glass is chemically inert, impermeable
to all liquids and gases, sanitary and
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odorless, capable of transparency, and
versatile and adaptable in that it can be
molded to almost any shape and size (3).
The manufacturing process is usually a
fully integrated, one-step process that
begins with raw material feedstock and
yields a finished product at the same
location. Basic raw materials include
soda ash, limestone, and sand. Lime-
stone and sand are cheap and abundant.
Gullet, or waste glass, can be used in
lieu of soda ash, which is in demand.
State of the Art for Resource
Recovery of Plastic Wastes
Plastic Waste Generation
Plastic waste is generated from in-
dustrial-manufacturer, commercial,
and municipal sources. The amount of
plactic wastes generated in 1977 and
projected for the years 1980-1990 is
presented in Table 1.
Plastics production in 1977 totaled
33,948 million Ib (1). Of that amount,
approximately 80 percent was thermo-
plastic, and thus amenable to remelting
and refabrication, to a certain extent.
The largest single end use for plastics is
in packaging, although most plastics are
put to long-term uses. As a result, the
source of plastics found in the municipal
waste stream is normally plastics pack-
aging. No hard data exist to indicate
exact quantities of plastics recovered
from waste streams. Estimates indicated
that 4,850 million Ib were recovered,
primarily through industrial recycling
(1). Solid wastes are produced at es-
sentially every step in the manufacture
of plastics, with the post-consumer
segment accounting for most of it.
Resource Recovery from
Plastic Wastes
Because of the tremendous growth in
the use of polymers or plastics, especially
for short-term packaging, increasing
attention has been focused on its re-
covery. But the recovery of plastics from
municipal refuse within the United
States is basically embryonic. Currently,
only specific plastics that are uncon-
taminated and segregated from other
polymers and wastes have potential for
recovery. Polyester-polyethylene ter-
ephthalate (PET) bottles, polyvinyl chlo-
ride (PVC) scrap, polyethylene containers,
and high-density polyethylene (HOPE)
film are currently sporadically recovered
for recycling. As a result, energy derived
from combustion in waste-to-energy
Table 1. Estimates and Forecasts by Year of Plastic Wastes Generated and
Recovered**
Category of Waste
1977
1980
1985
1990
Total solid waste (MTf
Municipal generation (MT)
Commercial generation (MT)
Industrial generation (MT)
Recovery (MTf
Total waste as generated (MT)
Total waste as disposed (MT)
Plastic in mixed wastes, %
148
6.9
0.8
0.6
1.4
6.9
6.9
4.9
160
8.4
0.9
0.7
1.6
8.4
8.0
5.3
180
11.2
1.2
1.0
2.4"
11.0
9.6
6.2
200
13.4
1.4
1.2
2.8"
13.2
10.0
6.6
Plastics recovery as a % of plastic
wastes (municipal) for energy
recovery 0
4.2
13.4
24.3
"Assume no variation in industrial-municipal, commercial ratios of generation.
^Composite of Midwest Research Institute and PES estimates.
''Million tons.
^Recovery is composite of source separation and energy recovery.
"Incorporates PET recycling at 25% efficiency.
plants most likely represents the future
prevalent made of plastics recycling.
A less familiar but equally important
area is that of pre-consumer wastes, or
those generated by producers, proces-
sors, and fabricators of products. Though
recovery of plastics from municipal
refuse is not extensive, industrial (and
to a certain extent commercial) recovery
is quite extensive. Essentially, scrap
recovery has long ceased to be an after-
thought in most plastic processing
operations. Scrap handling has the
potential for being as important a plastic
processing operation in its own right as
processing virgin polymers, since the
rising costs of feedstocks make even
small losses significant.
Reuse strategies have shown that
clean and single material plastic waste
streams derived from municipal waste
(PET, for example) can be collected and
recycled. Such activities are limited,
however, and are useful only for bever-
age packaging.
Except on such limited bases, recovery
of plastic materials from the mixed
municipal waste stream appears to be
technically or economically unfeasible
at present. The greatest potential for
successful plastic waste recovery seems
to be (a) the derivation or recovery of
energy from combustion of a mixed
plastic/organic waste fraction in the
municipal waste stream, (b) the enhance-
ment of volume reduction through
various forms of thermal treatment by
utilizing the high energy value of plas-
tics, and (c) selected source separation.
State of the Art for Recovery
of Glass Wastes
Glass Waste Generation
Waste glass generation in the United
States stems primarily from industrial,
commercial, and municipal sources.
The total glass production in 1978 was
estimated to be about 20 million tons.
About 70 percent of this glass was
container glass, but the amount of
container glass found in municipal
waste is reported to be about 90 percent
(4). Such a figure is expected, since in
the absence of reuse systems, the
useful life for container glass is rela-
tively short when compared with other
glass types such as flat glass and fiber-
glass. According to the latest available
statistics, glass is reported to make up to
10 percent of the total municipal waste-
load (5) of 148 x 106 tons. Table 2
presents a projection of glass waste and A
the amounts recovered from mixed "
municipal waste for the period 1980-
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Table 2. Projection of Glass Waste Generation, Processing, and Recovery, for
Municipal Waste'
Category
1972
1975
1980
1985
1990
Total solid waste (MTf 130 140 160
Glass available (MT) 13 14 16
Glass as % of
total waste 10.1 10.5 10.3
Glass processed for
recovery* (MT) 0 0.020 0.170
Glass recovery (MT)
source separation
collection 0.175 0.180 0.225
180
16
16
9.3
0.540 0.860
0.225 0.225
Cutlet dealers
Waste recovery plants
Total resource recovery
of glass (MT)
Amount recovered as %
of total glass waste
0.100
0
0.275
2.8
0.085
0.010
0.275
1.8
0.050
0.100
0.375
2.3
0.050
0.350
0.600
3.6
0.050
0.600
0.850
5.0
"Estimates by Midwest Research Institute.
"Million tons.
"Processed in central facility with glass subsystem.
1990, incorporating such factors and
beginning with the base year of 1972.
Resource Recovery from
Glass Wastes
The recovery of glass from municipal
waste within the United States today is
more representative of any emerging
technology rather than an age-old prac-
tice. Nonetheless, a secondary materials
industry does exist, and methods for
recovering materials from municipal
waste are achieving new levels of
sophistication and success.
Within the recycling "closed system,"
three defined segments exist: (a) glass
manufacturing and secondary materials
users; (b) cutlet dealers; and (c) munici-
pal and private collection programs.
Glass manufacturers are the principal
actors. Raw material users have tradi-
tionally used glass cullet derived from
off-specification glass, etc. Most re-
cycled glass from post-consumer sources
has been used by glass container manu-
facturers to produce new containers.
Recently there has been a shift to
composites of glass, plastic, and fibers.
These new secondary uses promise
glass recycling an expanded cullet
capacity with reduced specification
levels. In addition, economic problems
exacerbated by inflation and energy
shortages have improved the economics
of smaller-scale enterprises. The theory
is that small scale, local industries will
be more apt to utilize locally derived
cullet, thereby eliminating high transfer
costs (6).
Cullet dealers represent a second
segment. As intermediate processors,
they provide the important function of
aggregation and quality control. Cullet
dealers are, however, a diminishing
segment of the industry. Fewer than 20
dealers exist today.
Finally, the delivery or collection
system, represented by grass roots re-
cyclers, municipalities, and small busi-
nesses, form the third segment. They
often deal through intermediate proces-
sors, although larger programs may sell
directly to a manufacturer.
Environmental and
Economic Evaluation
In the commercial and manufacturing
segments, resource recovery activities
have been straightforward. The eco-
nomics are based on materials of known
composition and quality that are free of
contamination. In particular, the eco-
nomics of the plastics industry is very
much dependent on the recycling of
scrap (waste) internally or by sale. Scrap
is usually reintroduced into the produc-
tion stream either directly or downstream
of the resin manufacturers. Through the
recovery of plastic and glass wastes,
adverse environmental and economic
impacts are mitigated and beneficial
impacts are realized.
By contrast, plastic and glass wastes
from municipal sources are mixed with
other wastes and are contaminated.
They must then be separated from other
solid wastes or at least concentrated
into suitable fractions, homogenized,
and decontaminated before any suc-
cessful utilization. Recycling from mu-
nicipal sources is presently limited. For
both plastic and glass cases, there
exists a paucity of environmental and
economic information. As a result,
environmental and economic impacts
are difficult to assess. Moreover, no
existing commercial recovery system
(other than certain pilot mechanical and
source separation systems) recovers
plastics or glass from MSW as a sole
product. Consequently, identification of
specific impacts and costs is, at best, a
most difficult proposition.
Obstacles to Recycling
Current obstacles exist that inhibit
increased glass and plastic recycling.
One obstacle is the general price dif-
ferential between virgin and recycled
materials. Virgin materials have been
cheaper in the United States because
natural resources have been plentiful,
because public policies favor virgin
materials, and because environmental
and other social costs (externalities)
have been omitted from the price (7). For
example, public policy on Federal land
use gives competitive advantage to
virgin material extractors (8), and tax
structures also favor extractive indus-
tries. Railroad freight rate discrimina-
tion is another advantage enjoyed by
industries dealing with virgin materials
(9).
Research on Plastic and Glass
Waste Recovery/Reuse
Basic plastic waste recovery research
programs generally focus on the site-
specific needs of manufacturers. These
include: (a) processes for the chemical
or mechanical separation of various
blends of plastic waste, (b) processes or
additives that improve the bonding
characteristics of mixed plastic types, (c)
development of specifications to aid
consumers in identifying plastic and to
enhance recyclability, and (d) processes
and systems to upgrade segregated
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plastic scrap types normally uniformly
contaminated (e.g., PVC molded around
copper wire).
Research efforts focusing on munici-
pal refuse as a source of plastic for
recovery are combustion-energy re-
covery operations, which favor the high
BTU content (10,000 BTU/lb) of plastics,
selected solvent separation, cryogenics,
source separation, air separation, elec-
trodynamics, sink flotation, and research
related to PET bottles.
Research efforts for glass recovery/
reuse have been concerned with me-
chanical separation, source separation,
new secondary products, and reuse
programs. Foremost, a market for the
recovered glass must exist, and presently
there are only limited markets. One area
of research that has been promising for
glass waste recovery is its use in sec-
ondary products such as glasphalt and
glass foam insulation.
Conclusions
The following conclusions were
developed based on the state of the art:
Plastics
1. Industrial and commercial sources
can efficiently recycle using simple,
proven technology. The main rea-
sons are that waste materials are
concentrated, relatively uncon-
taminated, and usually of known
quality and composition.
2. No proven commercial-scale re-
covery system singularly effects
recovery of waste. Rather, such
materials are recovered as one
component of an overall recovery/
collection approach.
3. Secondary products, on the whole,
have not had specifications devel-
oped on product reuse. This situa-
tion has acted as a barrier to
increased use, since reuse
processes have not necessarily
been standardized.
4. Combustion and energy recovery
hold the greatest promise for re-
covery of the bulk of the plastics
fraction of the solid waste stream
because of the number of different
types of plastics and the differing
degrees of degradation of compo-
nents.
5. Source separation from the indus-
trial to the residential levels con-
stitutes the only significant recovery
of waste from municipal waste
sources.
6. For the immediate future, indus-
trial and commercial sources will
constitute the majority of recycling
activity. Recovery from post-con-
sumer wastes must overcome
significant market, institutional,
technical, transportation, and
specification barriers to compete
successfully with virgin products.
Glass
1. Glass manufacturers claim that
25 percent of the post-consumer
waste stream could presently be
recycled. Transportation and col-
lection/delivery problems and
contaminant levels mitigate
against such recovery.
2. Industrial and commercial sources
can efficiently recycle using
simple, proven technology. The
main reasons are that waste
materials are concentrated, rela-
tively uncontaminated, and usually
of known quality and composition.
3. Municipal wastes are most often
mixed with other refuse compo-
nents; hence recovery is difficult
and not economical. Also, the
ease of obtaining raw materials
prevents a significant recovery
incentive.
4. No proven commercial-scale re-
covery system singularly effects
recovery of glass. Rather, such
materials are recovered as one
component of an overall recovery/
collection approach.
5. Source separation often lacks in
collection equipment and efficient
processing; hence recovery is
inhibited.
6. Secondary products, on the
whole, have not had specifica-
tions developed on product reuse.
This situation has acted as a
barrier to increased utilizations,
as reuse processes have not
necessarily been standardized.
7. Mechanical recovery systems for
glass wastes have primarily orig-
inated from other industries such
as mining. They lack proven usage
in waste separation, where
moisture, composition, physical
properties, and economics vary
widely.
8. A national market for mixing
color glass cullet could signifi-
cantly enhance recovery of glass
wastes from municipal sources
by simplifying collection and
processing.
9. Source separation from the in-
dustrial to the residential levels
constitutes the only significant
recovery of waste from municipal
waste sources.
10. For the immediate future, indus-
trial and commercial sources will
constitute the majority of recycling
activity. Recovery from post-con-
sumer wastes must overcome
significant market, institutional,
technical, transportation, and
specification barriers to compete
successfully with virgin products.
The full report was submitted in ful-
fillment of Contract No. 68-03-2708 by
Pacific Environmental Services, Inc.,
under the sponsorship of the U.S. Envi-
ronmental Protection Agency.
References
1. National Center for Resource Re-
covery, Inc. Plastics Fact Sheet,
October 1973. Washington, D.C.
2pp.
2. Marynowski, C.W. Disposal of Poly-
mer Solid Waste by Primary Polymer
Producers and Plastics Fabricators.
EPA-PA 86-68-160, U.S. Environ-
mental Protection Agency, Washing-
ton, D.C. 1972. 92pp.
3. Hutchins, J.R. and R.V. Harrington.
Glass. Corning Glass Works. Reprinted
from Encyclopedia of Chemical
Technology, 2nd edition, vol. 10, pp.
533-604.
4. Duckett, E.J. Glass Recovery from
Municipal Solid Waste. National
Center for Resource Recovery, Inc.
Washington, D.C., June 1978.
5. Anon. Fourth Report to Congress on
Resource Recovery and Waste Re-
duction. SW-600, U.S. Environmen-
tal Protection Agency, Washington,
D.C., 1977, 142pp.
6. Seldman, N.R. Anthony, J. Huls, M.
Kershner, J. Specter, and J. Sullivan.
National Recycling Research Agenda
Project. NSF-OPA-79-170-13, Na-
tional Science Foundation, Wash-
ington, D.C., 1980. 100pp.
7. Seldman, N. and D. Knapp. Waste
Knot; The Politics of Garbage Re-
cycling. Institute for Local Self Re-
liance. Washington, D.C., 1981.
8. League of Woman Voters. Recycle.
Washington, D.C. 1972. 40 pp.
9. Resource Conservation Committee.
Choices for Conservation. Report to
President and Congress. U.S. Gov-
ernment Printing Office, Washing-
ton, D.C., July 1979. 130 pp.
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Tom Archer is with Pacific Environmental Services, Inc. Santa Monica, CA
90404, and Jon Huls is with Secondary Resources Development, Alexandria.
Va 22314.
Stephen C. James is the EPA Project Officer (see below).
The complete report, entitled "Resource Recovery from Plastic and Glass
Wastes," fOrder No. PB 81 -223 471; Cost: $ 14.00, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
> U.S GOVERNMENT PRINTING OFFICE: 1081 -757-01Z/7306
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