United States
Environmental
Protection Agency
Office of Solid Waste Office of Air Off ice of Research EPA/530-SW-87-02TT
and Emergency Response and Radiation and Development June 1987
Washington, DC 20460 Washington, DC 20460 Washington, DC 20460
SEPA
Municipal Waste
Combustion Study
Recycling of Solid Waste
-------
June 1987
MUNICIPAL WASTE COMBUSTION STUDY:
RECYCLING OF SOLID WASTE
Prepared by:
Radian Corporation
3200 East Chapel Hill Road/Progress Center
P.O. Box 13000
Research Triangle Park, N.C. 27709
For Information Contact:
David Cleverly
Pollutant Assessment Branch
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
EPA Contract No, 68-02-4330, Work Assignment 9
Radian Project No. 239-001-09
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DTSCLAIMER
This document has been reviewed and ape oved for publication by the
Office of Air and Radiation, U.S. Environme al Protection Agency. Approval
does not signify that the contents necessar.iy reflect the views and policies
of the Environmental Protection Agency, nor does the mention of trade names or
commer al products constitute endorsement or recommendation for use.
-------
TABLE OF CONTENTS
Page
CONTENTS i
LIST OF TABLES i ii
LIST OF FIGURES iv
1.0 INTRODUCTION AND SUMMARY 1-1
2.0 EXTENT OF CURRENT RECYCLING 2-1
2.1 RECYCLING IN THE UNITED STATES 2-1
2.2 RECYCLING IN OTHER COUNTRIES 2-4
2.2.1 Sweden 2-4
2.2.2 Norway 2-5
2.2.3 Germany 2 -~5
2.2.4 Denmark « 2-7
2.2.5 Italy 2-8
2.2.6 Japan 2-8
2.3 REFERENCES 2-10
3.0 SEPARATION METHODS 3-1
3.1 SOURCE SEPARATION 3-1
3.1.1 Source Separation Methods 3-1
3.1.2 Source Separation Programs At Some Localities 3-4
3.2 CENTRALIZED PROCESSING 3-5
3.2.1 Description Of Centralized Processing Techniques 3-6
3.2.1.1 Separation Techniques For Ferrous Metals 3-8
3.2.1.2 Separation Techniques For Nonferrous Metals... 3-8
3.2.1.3 Separation Techniques For Glass 3-9
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Page
3.2.1.4 Seoaration Techniques For Paper 3-9
3.2.2 Description Of Commercial Centralized Processing
Systems 3-10
3.2.2.1 Sorain-Cecchini System 3-10
3.2.2.2 Stardust '80 3-11
3.2.2.3 ORFA Process 3-13
3.3 REFERENCES 3-16
4.0 MATERIALS AND MARKETS 4-1
4.1 ALUMINUM 4-1
4.2 FERROUS METALS 4-2
4.3 GLASS 4-3
4.4 PAPER 4-5
4.5 PLASTICS 4-8
4.6 WOOD 4-10
4.7 RUBBER 4-10
4.8 COMPOST 4-11
4.9 REFERENCES 4-13
5.0 EFFECTS OF RECYCLING ON COMBUSTION 5-1
5.1 EFFECTS OF RECYCLING ON THE COMBUSTION PROCESS 5-1
5.2 EFFECTS OF RECYCLING ON EMISSIONS FROM COMBUSTION 5-4
5.3 REFERENCES 5-8
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LIST OF TABLES
Table Page
2-i DISCARDS AND RECOVERY OF MATERIALS IN THE MUNICIPAL WASTE
STREAM, 1984 2-3
2-2 SEPARATION AND UTILIZATION OF RECOVERED WASTES IN SWEDEN IN
1981 AND 1982 2-6
3-1 SOURCE SEPARATION METHODS USED TO RECOVER RECYCLABLES FROM
MUNICIPAL WASTE 3-2
3-2 CENTRALIZED PRESSING TECHNIQUES USED TO RECOVER RECYCLABLES
FROM MUNICIPAL WASTE 3-7
11
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LIST OF FIGURES
Figures
2-1
3-1
3-2
Gross Discards, Materials Recovery, Energy Recovery, and Net
Discards of Municipal Solid Waste, 1960 to 2000
Separation Steps in Sorain-Cecchini Process
Optional Recovery Processes Available in Stardust
'80 Svstem
Page
2-2
3-12
3-14
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1. INTRODUCTION AND SUMMARY
This report is an assessment of recycling of solid waste as an
alternative or augmentative waste management strategy to municipal waste
combustion. The information presented in this report was developed as part of
a comprehensive, integrated study of municipal waste combustion. An overview
of the findings of this study may be found in the Report to Congress on
Municipal Waste Combustion (EPA ">0-SW-87-021a). Other technical volumes
issued as part of the Municipal kaste Combustion Study include:
o Emission Data Base for Municipal Waste Combustors
(EPA/530-87-SW-021b)
o Combustion Control of Organic Emissions (EPA/530-SW-87-021c)
o Flue Gas Cleaning Technology (EPA/530-SW-87-021d)
o Cost of Flue Gas Cleaning Devices (EPA/530-SW-87-021e)
o Sampling and Analysis of Municipal Waste Combustors
(EPA/530-SW-87-021f)
o Assessment of Health Risks Associated with Exposure to Municipal
Waste Combustion Emissions (EPA/530-SW-87-021g)
o Characterization of the Municipal Waste Combustion Industry
(EPA/530-SW-87-021h)
As landfill areas available for municipal waste disposal have become
increasingly scarce, renewed interest has been generated in volume reduction
as a part of waste management. A great deal of emphasis has been placed on
combustion as a waste volume reduction method, but there has also been an
increased interest in recycling materials that would otherwise end up in
landfills. While recycling is not expected to eliminate the need for
combustion, it is being increasingly seen as a possibility for augmenting the
volume reduction achieved through combustion.
Although the United States is not as active in the area of materials recycling
from waste as are some other countries, in 1984 about 10 percent of material
that would otherwise have ended up in disposal facilities was recovered and
reused. Most of the recovery in the United States was accomplished through
1-1
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source separation, that is, manual separation by the generator, rather than
separation from mixed refuse in centralized waste processing facilities.
There are thousands of source separation programs in operation across the
United States including 400 to 500 curbside recycling programs. Some states,
particularly in the Northeast, have made participation mandatory. Added to
the source separation programs, there are some 30 to 40 centralized waste
processing plants, separating materials from mixed refuse. These plants are
producing refuse-derived fuels and, in the process, are removing mostly
non-combustibles from the waste.
Centralized processing methods are becoming increasingly sophisticated
and effective at separating waste materials. A notable state-of-the-art
system developed in Europe, the Sorain-Cecchini process, is an integrated
recovery system that can produce paper pulp, animal feed, compost, aluminum
scrap, ferrous scrap, densified refuse derived fuel, and pelletized
polyethylene for production of sheet plastic used in garbage bags. A simila'r
process known as Stardust '80 has been developed and commercially demonstrated
in Japan. Moreover, plans are currently underway to construct integrated
waste recovery facilities in the United States based on the ORFA process.
Methods for separation and uses for recovered materials have been
established for paper, glass, scrap ferrous metals, aluminum, wood waste, yard
waste, and rubber. Also, separation methods and markets for recovered
plastics are currently the subject of rapidly advancing research. At the
present time, technical and economic factors combine to make paper and
aluminum the most extensively recycled materials from U.S. waste.
Recycling, as a part of an overall waste management strategy, should be a
positive measure for most localities. In general, recycling of noncombustible
materials would have a positive effect on combustion operations, allowing
the potential for smaller facilities, more reliable operation, and decreased
ash handling requirements.
The effect of recycling on the feasibility of combustion should be
considered, however, in the context of local refuse characteristics. For
example, one of the constituents of waste that is widely recycled is paper.
Because paper contains the largest portion of the heating value in the waste,
recycling goals for paper should be consistent with combustor design heating
1-2
-------
value requirements. Due to site-specific variations in refuse composition,
markets for recycled materials, combustor design option limitations, and other.
factors, judgements on the optimum combination of recycling and combustion for
a given waste management plan are most appropriately made on a site-specific
basis.
In addition to augmenting the volume reduction achievable through
combustion of municipal waste, recycling may provide an opportunity for
reducing emissions of hazardous materials resulting from combustion or direct
landfill of certain waste materials. In particular, recycling of alkaline
batteries, which contain about 1 percent by weight of mercury, represents a
potential means of substantially reducing mercury emissions from municipal
waste combustors. In Sweden, it is estimated that two-thirds of mercury
emissions from municipal waste combustors would be eliminated by recycling
alkaline batteries. This is significant in light of the fact that emissions
tests of state-of-the-art control technologies applied to municipal waste-
combustors have demonstrated only 30 to 40 percent control of mercury
emissions. (See "Municipal Waste Combustion Study: Emission Data Base for
Municipal Waste Combustors;" EPA/530-SW-87-02/b.) Furthermore, to the extent
that combustion conditions are improved through removal of noncombustible
materials, pollutants resulting from the combustion process (e.g. organics,
carbon monoxide) should also be reduced through recycling of noncombustibles.
Strategies for reducing emissions of other pollutants from municipal
waste combustion by removing materials from the waste are not as easily
discernible. For example, measurements at one test facility showed reduction
in lead and cadmium emissions when metals and glass are removed from the waste
prior to combustion. Metals such as cadmium, lead, and chromium, however, are
contained In paints, colorants, and stabilizers are distributed throughout the
combustible portions of the waste. Therefore, elimination of their emissions
through removal does not appear likely. Further, the major sources of
chlorine in the waste, and hence the sources of substantial quantities of HC1
emissions, are paper and plastics. But these materials also have the highest
heating values of the materials in the waste, so their total removal would not
be practical. Finally, removal of polyvinyl chloride (PVC) from the waste has
been suggested as a strategy for reducing emissions of chlorinated dibenzo-p-
dioxins (CDDs) and chlorinated dibenzofurans (CDFs). The mechanisms for
1-3
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formation of CDDs and CDFs in the combustion of waste are not thoroughly
understood at this time. While research shows that PVC can act as a precursor
in CDD/CDF formation, it is thought that other materials in the waste may also
participate in chemical reactions leading to CDD/CDF formation. Therefore,
the effectiveness of reducing CDD/CDF through removal of PVC is not clear.
In this report background information on recycling, its status in the
United States and abroad, and its technical feasibility are examined. Also,
because recycling is expected to be an integral part of a solid waste
management plan that includes combustion, potential effects on combustion of
removing materials from the waste are considered. This report resulted from a
brief investigation of a subject area in which a lot of things are happening.
Thus, it is designed to convey a sense of the current status of recycling and
its technical feasibility, rather than to embody comprehensive authoritative
reference material.
In Section 2, the current extent of recycling in the United States and in
several other countries is reviewed. The material on the current recycling
programs and approaches is followed by two sections on feasibility of
recycling. Section 3 contains information on methods for separation of
materials and Section 4 contains information on uses and markets for recovered
materials. Finally, Section 5 seeks to address questions concerning the
effects of recycling activities on combustion processes.
This work was performed by Radian Corporation under EPA Contract
68-02-4330, Work Assignment 9. EPA's Work Assignment Manager was
Mr. David Cleverly of the Strategies and Air Standards Division of the Office
of Air Quality Planning and Standards.
1-4
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2. EXTENT OF CURRENT RECYCLING
2.1 RECYCLING IN THE UNITED STATES
Recycling in the United States is on the increasing, as shown in Figure
2-1.* The quantities represented in the figure are reportedly conservative,
so that further increases in recycling and recovery activities would cause an
increase in the materials recovery segment shown. In 1984 total material
recovery amounted to about 10 percent of total discarded material, as shown in
Taole 2-1. This is compared to about 25-30% of municipal waste that has been
described as "easily" recyclable. Most of the recovery to date has been
3 4
accomplished through source separation. '
There is a movement underway in the U.S. to increase source separation
of constituents in municipal refuse. Recycling programs are being developed
by State and Local governments throughout the United States, but particularly
in the Northeast where land for disposal is scarce. The number of such
recycling programs is estimated in the thousands.
There are 400 to 500 curbside recycling programs of various sizes
operating across the country with a growing number, particularly in the
Northeast, stipulating mandatory participation. Typical participation rates
for voluntary curbside collection programs in the United States are reported
to be about 33 percent. Some programs, however, report much higher voluntary
participation rates. For example, a voluntary curbside recycling program in
San Jose, California reports 70 percent participation, while another program
g
in Kitchener, Ontario (Canada) reports 80 percent participation.
Sixty-eight municipalities in Pennsylvania report an average participation
a
rate of 54 percent and, Woodbury Township in New Jersey reports recycling
45 percent of its waste. Voluntary residential curbside collection programs
are estimated to reduce the amount of waste discarded in a service area by
about 8 percent. This estimate is based on a typical 33 percent participation
rate and assumes recyclables account for about one quarter of most residential
waste.
2-1
-------
200-
180-
160-
140
g 120-
o
s 100-
jO
60-
40-
20-
Gross Discards
Material Recoveredi^-Mv1';
^,.i«,% i'_»-,s'-rxt''-^'^-.*"'^
•\~_il»ii^i
Energy
•Net Discards
1960
1965
1970
1975
1980
'< f"1'
1985
1990
1995
2000
Finure 2-1. Gross discards, materials recovery, energy recovery, and net discards
of municipal solid waste, 1960 to 2000.
2-2
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TABLE 2-1. DISCARDS AND RECOVERY OF MATERIALS IN THE MUNICIPAL WASTE STREAM, 1984
(In millions of tons and percent)
1
Materials
Paper and Paperboard
Glass
Metals
Ferrous
Aluminum
Other Nonferrous
Plastics
Rubber and Leather
Textiles
Wood
Other
TOTAL NONFOOD PRODUCT WASTES
Food Wastes
Yard Wastes
Miscellaneous Inorganic Wastes
TOTAL WASTES DISCARDED
Gross
Discards
62.3
13.9
11.3
2.1
0.3
9.7
3.4
2.8
5.1
0.1
111.1
10.8
23.8
2.5
148.1
% of
Discards
42.1
9.4
7.6
1.4
0.2
6.5
2.3
1.9
3.4
0.1
75.0
7.3
16.1
1.7
100.0
Postconsumer
Materials
Recovery
12.9
1.0
0.3
0.6
0.0
0.1
0.1
0.0
0.0
0.0
15.1
0.0
0.0
0.0
15.1
Net
Discards
49.4
12.9
11.0
1.5
0.3
9.6
3.3
2.8
5.1
0.1
96.0
10.8
23.8
2.5
133.0
% of
Discards
37.1
9.7
8.3
1.1
0.2
7.2
2.5
2.1
3.8
0.1
72.2
8.1
17.9
1.9
100.0
Details may not add to totals due to rounding.
-------
Mandatory programs are currently achieving participation of at least 50
percent and, in some cases, as high as 80 to 90 percent. The proportion of
the total waste stream diverted by these mandatory programs is estimated to be
12 to 23 percent. Container deposit laws have resulted in 80 to 95 percent
recovery of returnable containers, reducing total waste in areas where they
211
apply by about 5 percent. ' No statistics were found for the amount of
waste diverted by central collection centers.
Materials being recovered most successfully in source separation programs
include paper, aluminum cans, and glass.
In addition to curbside recycling and source separation programs, there
are 30 to 40 centralized materials separation facilities operating in the U.S.
These plants are recovering materials for reuse from mixed refuse. Waste Age
listed 33 U.S. separation facilities with total design capacity of 41,000 tons
12
per day of waste operating in the U.S. in its November 1985 update. While
the list may not be all inclusive, previous experience with this, compilation
indicates that it probably contains most of the facilities.
2.2 RECYCLING IN OTHER COUNTRIES
2.2.1 Sweden
In Sweden about 40 to 45 percent of domestic waste is landfilled, about
45 to 50 percent is incinerated, and about 10 percent is separated and/or
composted in central processing plants. In the period between 1977 and 1982
about 15 to 20 centralized processing plants were built. In che first two
years of operation problems occurred with the new, undemonstrated technology.
Even bigger problems surfaced in the lack of markets for materials produced in
the centralized processing facilities. Meeting the high quality
specifications placed on recycled materials has been particularly difficult
for recovered materials. Moreover, refuse derived fuel (RDF) produced by the
processing plants has not been successfully burned in equipment designed and
built for burning other solid fuels. Compost produced in the centralized
plants has also been difficult to market because of its glass and plastic
content. Recent reports say that the compost is currently being used as
landfill cover. Still, with all the problems, progress is being made as shown
in Table 2-2, and the Swedish government is continuing to encourage and
promote recycling of municipal waste.
2-4
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Because of the negative experience with centralized separation plants,
there has been a growing interest in source separation. An advantage is seen
in the cleaner recovered fractions. During 1983 recovery of newspapers and
magazines reached 52 percent. An estimated 200,000 tons were collected, out
of an estimated recoverable portion of newspapers and magazines in Sweden's
waste of 220,000 tons per year. About 90 percent of the population
participates in wastepaper recovery (230 to 240 of 284 municipalities).
2.2.2 Norway
About 40 percent of the waste entering a centralized separation plant in
Oslo is reportedly processed into ferrous, paper, and plastic waste fractions,
which are then recycled. This state-of-the-art facility went into full scale
operation in 1985, processing household waste to paper, plastic chips, and
ferrous metal for use in finished products. It also has the capability to
compost grass, leaves and food waste.
The recovered paper is fed to a small pulper, then to an additional
pulping facility for marketing to a tissue manufacturer. The pulp, treated
with hydrogen peroxide, would reportedly be acceptable in Norway for food
packaging as well as for tissue and newsprint. The paper recovery program is
in accord with Norway's virgin fiber conservation policy which limits the
14
amount of forest products available for paper production.
14
2.2.3 Germany
Two notable features of German recycling efforts are a paper recycling
policy and numerous agricultural composting plants located in rural areas.
The government has a procurement policy favoring recycled paper, and even
school supplies are required to have a reeded paper content. In
Baden-Wurttemburg, compost is used in vineyards, gardens, parks, and orchards.
One environmental concern is the potential presence of heavy metal
comtamination in the compost. Heavy metals have reportedly bioaccumulated in
leaves of grape vines but not in the grapes themselves where compost was used
as fertilizer. Despite these concerns, composting is expected to increase to
90,000 tons per year in Baden-Wurttemburg.
2-5
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TABLE 2-2. SEPARATION AND UTILIZATION OF RECOVERED WASTES IN
SWEDEN IN 1981 AND 1982
(In metric tons)
Separated Used or sold
1981 1982 1981 1982
Iron Scrap
Plastic
Separated Fuel
Compost
4400
2400
37,000
108,000
6800
3900
75,800
121,500
200
0
4400
29,400
1300
30
32,300
56,000
2-6
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In addition, landfill ing in Baden-Wurttemburg has been limited to 50
percent of total waste disposal capacity. Thus about 50 percent of MSW is
managed by combinations of refuse recycling and refuse combustion.
Currently in Bavaria landfills account for only 30 percent of waste disposal
capacity, and, therefore, recycling and combustion are the major means of
waste disposal.
Another feature noted in Germany's waste management included collection
bins located at combustor sites „, Wurzburg and Stuttgart for separation of
hazardous items (batteries, aerosols, explosives) from waste before they enter
the combustor. By removing tnese items plant operators hope to avoid damage
to equipment and to minimize emissions of metals.
2.2.4 Denmark14
In Copenhagen labelled containers are available for disposal of
segregated waste, e.g., yard waste, furniture, aerosol cans, etc. Also in
Denmark, aluminum cans are not used for beverages, and beverage containers
must be commercially reusable. Containers were reported to be used an average
of 30 times compared to average usage of less than 10 times in U.S. markets.
The return rate was estimated to be 99.6 percent.
Government procurement efforts have helped to create a strong market for
recycled paper. Danish cardboard is more than 90 percent recycled and
photocopy paper contains 45 percent recycled paper and straw. All available
recovered ferrous scrap is recovered by the Danish steel industry, and
discarded tires are being considered for use in highway asphalt. Also under
investigation is the use of food waste from restaurants and institutions for
processing into pet food. A plastics reprocessing plant is scheduled to open
soon with a capacity of 25,000 tons per year for processing source separated
plastic.
2.2.5 Italy
The city of Rome has several materials separation and recycling plants
based on the Sorain-Cecchini process. These plants recycle about 65 percent
of the waste (about 500,000 tons/year) they receive from Rome. ' Paper,
p.lastic, ferrous metal, and compost are recycled.
2-7
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2.2.6 Japan
In 1983, about 67 percent of municipal solid waste collected in Japan was
incinerated and the remainder was landfilled. The shortage of available
landfill space has encouraged the practice of combustion which is expected
to continue to increase. Also, strong emphasis has been placed on recycling
and re; ,rce recovery (i.e., in the form of materials and/or energy) due to
Japan's dependency on imported resources. These objectives are being met
through a combination of source separation programs and centralized processing
facilities.16'17
Virtually all components of municipal solid waste are subject to
recycling and/or resource recovery including: paper, glass, ferrous and
nonferrous (i.e., aluminum) containers, plastic, and used electrical
appliances. In 1984, Japan recycled more than 50 percent of the discarded
18
newspaper as well as 81 percent of the discarded cardboard. The Japanese
government maintains a buffer stock of wastepaper to help stabilize the
19
market. By 1988, about 60 percent of returnable and nonreturnable glass
beverage containers is expected to be manufactured from used glass Gullet.
Supply of glass cullet is enhanced by an approximate return rate of 95 percent
of returnable beverage containers. Since 1977, Japan has operated a center
where discarded electric appliances (e.g., televisions, refrigerators, and
washing machines, etc.) are processed and separated into reusable
components. In general, Japan relies on non-profit organizations and
volunteer groups to promote public awareness and to encourage public
participation in recycling programs.
Centralized processing facilities play an important role in Japan's
recycling and resource recovery objectives. Commercial processes have been
implemented to sort mechanicall/ and manually valuable recyclables from mixed
refuse prior to combustion. Recently, Japanese innovations have been
demonstrated in pilot plants that produce methane gas from refuse by a high-
rate methane fermentation process. In addition, usable fuel oil has been
21
produced from paper and plastics by a pyrolysis oil recovery process. These
processes enhance resource recovery, are economical, and provide alternatives
to the predominant waste disposal techniques: landfill and combustion. The
Japanese government promotes these technological developments through
financial and tax incentives.
2-8
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2.3 REFERENCES
1. Franklin Associates, Ltd. Characterization of Municipal Solid Waste in
the United States, 1960 to 2000. Final Report. EPA Contract 68-01-7037,
Work Assignment 349. July 1986.
">. Clapham, W.B. An Analysis of the Potential Effect of Beverage Container
Deposit Legislation on Municipal Recycling Programs. Journal of
Environmental Systems, Volume 14, 1984-1985.
3. Cutter, Susan. Resource Recovery, An Overview in Environmental Policy:
Solid Wastes. Volume IV. Ballinger Publishing Company, Cambridge,
Massachusetts. 1985.
4. Resource Recovery Facts and Figures. Resource Recovery Update. Volume
9, No. 5. May 1980, p. 2. National Center for Resource Recovery, Inc.
Washington, D.C.
5. Bronstein, Scott. Where, Oh, Where to Empty the Trash in The New York
Times. September 14, 1986, p. 6F.
6. Hertzberg, Richard. New Directions in Solid Waste and Recycling.
BioCycle, Volume 27, January 1986. pp. 22-26.
7. Pettit, C.L. Trends in Collecting Recyclables. Waste Age, Volume 17,
June 1986.
8. Copeland, Vivian S. Recycling Success in Canada. 80% Participation!
Waste Age. November 1984. pp. 38-42.
9. Curbside Recycling in Pennsylvania -- 1985. Pennsylvania Department of
Environmental Resources. Bureau of Waste Management.
10. Hang, Walter Liong-Ting and Steven Romalewski. The Burning Question:
Garbage Combustion Versus Total Recycling in New York City. The New
York Public Interest Research Center, Inc. 1986.
11. Steisel, Norman, Paul D. Casowitz, and Joan Edwards. A Status Report on
Materials Recycling Activities in New York City. The City of New York
Department of Sanitation. December 1985.
12. Update: Resource Recovery Activities Report. Waste Age. 16 (11):
99-183. November 1985.
13. Rylander, H. Waste Management in Sweden. A National Report. Waste
Management and Research (3) 81-88. 1985.
14. Hinchey, Maurice, Chairman. New York State Legislative Commission on
Solid Waste Management in Norway, Sweden, Denmark, and Germany: Lessons
for New York. December 1985. Albany, N.Y.
2-9
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15. Institute for Local Self-Re!iance (1985). A Practical Alternative Solid
Waste Management Program for the City of Philadelphia. Submitted to the
Rules Committee, Philadelphia City Council. January 8, 1985. p. 98 as
cited in Hang, Walter Liong-Ting and Steven Romalewski. The Burning
Question: Garbage Combustion Versus Total Recycling in New York City.
The New York Public Interest Research Center, Inc. 1986.
16. Recycling '86: Turning Waste into Resources. Published by the Clean
Japan Center. 1986.
17. Irisawa, Shizuko. Aiming at Creation of a Beautiful Town and Resource
Reutilization. Clean Japan, No. 7, 1985.
18. Resource Recycling Journal. Volume VI Number 4. September/October 1985.
p. 8 as cited in Hang, Walter Liong-Ting and Steven Romalewski. The
Burning Question: Garbage Combustion Versus Total Recycling in New
York City. The New York Public Interest Research Center, Inc. 1986.
19. Hinchey, Maurice 0., chair. The Economics of Recycling Municipal Waste.
A Staff Report to New York State Legislative Commission on Solid Waste
Management. Albany, New York. 1986.
20. Ida, Nobuo. Example of Development and Operation of Municipal Refuse
Recycling System. Clean Japan, No. 7, 1985.
21. Stardust '80: Putting Refuse to Work. Agency of Industrial Science and
Technology MITI (Japan). No date.
2-10
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3. SEPARATION METHODS
Two primary methods are used to separate recyclable materials from MSW:
source separation and centralized processing. Source separation is
accomplished when the waste generator (e.g., residential consumer, retail
store, office building) sets aside recyclable wastes from other waste
materials. Centralized processing separates recyclable waste from mixed
municipal waste after it has been collected for disposal. This section
describes how waste materials are recovered by these two methods and describes
a few current programs in the United States and other countries that have
successfully implemented recycling using these separation methods.
3.1 SOURCE SEPARATION
Materials most commonly recovered through source separation are used
newspaper, glass, and aluminum cans from residential waste, used corrugated
boxes from commercial waste, and high-grade office paper from office
buildings. Source separation of other municipal waste components such as
plastics, rubber, and organic materials is currently performed on a much
smaller scale. Source separation methods in use for recovering recyclables
from municipal waste (Table 3-1) are described in the following section.
3.1.1 Source Separation Methods
Source separation of residential waste components is primarily achieved
through programs relying on curbside collection, neighborhood collection
centers, or a combination of the two. Additional source separation of glass,
aluminum, and in some cases, plastic containers is achieved as a result of
container deposit laws.
An estimated 400-500 curbside recycling programs of varying sizes are
operating in the United States. Two successful programs are operating in San
Jose, California and in Kitchener, Ontario (Canada). Both of these programs
attribute their success in part to making attractive containers available in
which residents can store recyclables and which are placed at the curb on
2 3
pick-up days. ' Neighborhood collection centers, while requiring less
equipment, personnel and maintenance than curbside collection programs,
generally achieve lower participation and lower volumes of materials.
3-1
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TABLE 3-1. SOURCE SEPARATION METHODS USED TO RECOVER RECYCLABLFS FROM MUNICIPAL WASTE
Residential Waste
Source Separation
Methods
Materials.
Recovered'
Commercial Waste
Source Separation
Technique
Materials
Recovered
CO
i
IVJ
Curbslde collection
Voluntary drop-off centers
Profit buy-back centers
Private/civic organization
fund-raising drives
Container deposit laws
Newspaper, glass*
aluminum cans
Newspaper, glass,
aluminum cans
Glass, metal cans,
newspaper* magazines,
corrugated boxes,
plastics and wood
Newspaper
Aluminum, glass, and
plastic containers
Collection by waste
dealers
Employee recycling
program
Corrugated boxes,
11quor and wine
bottles
High-grade office
waste, newspaper
Home composting programs Organlcs
^Programs vary 1n types of materials recovered. Materials listed are typical,
-------
Container deposit laws encourage consumers to separate and return used
glass, aluminum, and plastic beverage containers by placing a returnable
deposit on them. Such laws are currently in effect in Oregon, Maine,
Massachusetts, Vermont, Delaware, Connecticut, New York, Michigan, and
Iowa.5'6
Source separation of used corrugated boxes occurs primarily at retail
stores, supermarkets, factories, and department stores. Waste paper dealers
and recycling mills purchase waste from large generators of used corrugated
boxes and arrange for its removal. The businesses generating corrugated waste
typically operate compacting and baling equipment to reduce the volume of the
waste for economical storage and transport. Recycling is also practiced by
smaller ;usinesses generating relatively small amounts of used corrugated
boxes. Private individuals collect waste corrugated cardboard free of charge
from these businesses and then sell it to waste paper dealers. About 40
percent of used corrugated cardboard is recycled in this manner in the United
States.6
Paper recycling programs in offices are becoming increasingly common as a
form of source separation, since an estimated 90 percent of office waste is
waste paper. Office paper also is usually high grade. A recant survey of 12
unidentified office paper recycling programs sponsored by EPA indicated an
average reduction in office waste of 34 percent, and, in one case, of 78
percent. Offices with waste paper recycling programs request employees to
separate recyclable waste paper in desk top or centrally located bins. The
collected high-grade paper is then sold to a waste paper dealer who performs
additional sorting and removal of contaminants, as necessary, and arranges for
sale and transport of the waste paper to a recycling mill.
Current source separation practices also recover small quantities of
plastics, rubber, and organics from municipal waste. Plastic soft drink
containers are the only plastic waste currently recycled in significant
quantities in the United States. The major mechanism for collecting these
plastic containers is beverage container deposit legislation which requires
consumers to pay a returnable deposit on all disposable beverage containers.
Retailers collect the used containers and sell them to used plastic bottle
processors, where the used containers are sorted, cleaned, and processed to
remove contaminants (e.g., metal caps, labels) by a variety of manual and
3-3
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mechanical processes. Used plastic is currently used to make fiberfill and a
variety of extruded products. Some recycling centers provide facilities for
individuals to dispose of tires. Some communities encourage recycling of
organic waste through composting. The communities operate facilities which
accept and process organic waste into commercial compost to be used in
landscaping and gardening. In addition, some communities have established
programs providing materials and instructions for residents to perform their
2
own composting.
3.1.2 Source Separation Programs at Some Localities
Successful recycling programs involving source separation of residential
and commercial waste have been implemented in numerous communities across the
United States. Some of the most aggressive source separation programs have
been implemented or are currently being implemented in large cities where
development of alternatives to landfilling of municipal wastes bas become a_
major issue. Examples of source separation programs in these cities are
described below.
In New York City, the Department of Sanitation nas recently implemented
five pilot programs with the objective of increasing the level of source
reparation of residential wastes (i.e., newspaper, glass, and metal
containers). These programs include: (1) a newspaper recycling program for
high-rise apartment buildings; (2) establishment of "buy-back" centers in
lower income neighborhoods that purchase glass, aluminum, bi-metal cans, tin
cans, newspaper, magazines, corrugated paper, plastics, and wood from local
residents; (3) curbside collection of newspaper, glass, and metal cans, in
low-density neighborhoods; (4) establishment of a network of voluntary
drop-off centers in Manhattan; and (5) containerized recycling program for
materials other than newspapers in apartment buildings. Collectively, the
City of New York estimates these residential source separation programs could
result in a 5 percent reduction in the total municipal wastes generated, or
about 1300 tons/day. The New York State Returnable Container Law could
potentially recover an additional 5 percent of the residential waste in the
Q
form of glass, aluminum, and plastic beverage containers.
The City of New York has also implemented programs to promote recycling
of office waste paper. The City funds a private organization which provides
3-4
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technical assistance to offices interested in setting up office paper
recycling programs. Further, the City recently expanded their city agency
office waste paper recycling program with a resulting increase in tonnage of
paper recycled. The City also sponsors waste paper recycling programs for
non-profit organizations and a program with scrap paper dealers to promote
desk-top recycling by their clients.
In San Francisco, used newspaper is collected for recycling by community
groups as fund-raising drives, by community nonprofit recycling centers,
by for-profit buy-back recycling centers, and by garbage collectors. In
addition, an apartment newspaper recycling program has recently been
implemented. Other recyclables, including glass and aluminum cans, are also
collected by voluntary drop-off and buy-back recycling centers. Residential
curbside collection of recyclable materials was discontinued in San Francisco
because of illegal scavenging and because it could never service more than
about one-third of the population, due to San Francisco's unique demographics
and topography.
In addition to source separation programs for residential wastes, the
City of San Francisco has implemented several programs to increase recycling
of commercial wastes. The City collects wine and liquo~ bottles from bars and
restaurants, separates corrugated boxes from mixed waste at the City's
transfer station, and sponsors an office paper recycling program. This office
program provides technical assistance and promotional materials to offices
interested in establishing a paper recycling program. In addition, all city
offices currently operate a waste paper recycling program. Recycling of waste
wood and metals is performed at the City transfer station, and a composting
program recycles animal waste at the City Zoo. Altogether, the City
estimates mat about 22 percent of the residential and commercial waste
generated by the community is recycled.
3.2 CENTRALIZED PROCESSING
Virtually all of the post-consumer newspaper, glass, and aluminum
recycled in the United States is recovered by the source separation methods
described in Section 3.1. Yet only one-third or less of the total quantities
of these discarded waste items are currently recycled by source separation
methods. Another method for recovering additional recyclables in municipal
3-5
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waste is by centralized processing of the mixed waste stream. Centralized
processing to remove recyclables is practiced to a small degree at municipal
waste transfer stations. It is also a key operation performed in conjunction
with many waste-to-energy facilities, particularly those producing and firing
RDF. Centralized processing techniques used to recover recyclable wastes from
mixed waste (Table 3-2) are described in the following section.
3.2.1 Description of Centralized Processing Techniques
Transfer stations are operated by some communities to reduce
transportation costs when convenient landfills are unavailable. To further
reduce waste hauling costs, many transfer station operators selectively remove
recyclables from the dumped waste. In particular, large metal appliances,
white goods, auto parts, etc., are removed to prevent damage to compacting
equipment. Used corrugated cardboard, newspaper, and wood may also be
recovered from the mixed waste. These sorting operations generally are
8 12
performed manually at the transfer station. '
Another example of centralized processing to remove recyclables from
municipal waste is selective sorting of commercial office building waste.
Instead of being combined with residential waste, commercial office building
waste is routed to a processing plant whe>d nonpaper waste is manually
removed. This technique is practiced in at least one city (San Francisco).
Resource recovery facilities recover the materials and energy value of
municipal waste, thereby reducing the volume that has to be disposed in
landfills by about 60 to 90 percent. Some of these facilities separate metals
and other noncombustibles from the waste, and combust the remainder for fuel.
Others process the mixed waste to maximize recovery of all recyclables
including paper and plastics.
Two methods of separation are employed to remove recyclable waste
fractions: front-end separation and back-end separation. Front-end
separation removes recyclables before waste combustion. Back-end separation
removes recyclables from the combustion ash or from mixed fractions recovered
by front-end processing. Front and back-end separation techniques used to
recover recyclable materials are described below. Some commercial processes
using these techniques are described in Section 3.2.2.
3-6
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TABLE 3-2. CENTRALIZED PROCESSING TECHNIQUES USED TO RECOVER
RECYCLABLES FROM MUNICIPAL WASTE
Waste Type
Ferrous metals
Centralized Processing Techniques
Front-end separation
(before Incineration)
Magnetic separation
Back-end separation
(after Incineration)
Magnetic separation
Nonferrous metals
(e.g., aluminum)
Glass
Paper
Plastics
Jigging
Water elutrlatlon
Heavy media separation
Eddy-current separation
Electrostatic separation
J1 gg 1 ng/ sc r een 1 ng
Froth flotation
Optical sorting
Electrostatic separation
Manual sorting
A1r classification
Electrostatic separation
A1r classification
Electrostatic separation
Jigging
Electromagnetic separation
J 1gg1ng/screen1ng
Froth flotation
None
None
-------
3.2.1.1 Separation Techniques for_Ferrous Metals.
Magnetic seoaration--Ferrous metals are effectively removed from raw
refuse and combustor residue by magnetic separation. In front-end
separation processes, paper and other sheet materials entrained with the
ferrous fraction can be reduced with a multi-stage separator. The recovered
ferrous fraction may be air classified to separate "tin" cans from heavy
miscellaneous steel scrap. The tin cans must undergo a commercial detinning
process before being recycled as scrap.
Magnetic separation is also used to recover ferrous materials in
combustor residue. In contrast to ferrous scrap recovered by front-end
processes, ferrous recovered from back-end processes is cleaner having gone
14
through the combustion process.
3.2.1.2 Separation Techniques for Nonferrous Metals.
Jigging.--Jigging is a wet process that separates materials of different
specific gravities by pulsating water with a jig. Heavy particles settle on'
the screen and light particles are skimmed from the top. Jigging has been
demonstrated to separate aluminum effectively from heavy nonferrous metals
(zinc, lead, and tin) in raw refuse and to separate a glass and aluminum
fraction from heavy nonferrous metals in combustor residue.
Water e!utriation--In the water elutriation technique, a controlled
rising current of water is employed to create an effective, controllable
specific gravity. Light material floats to the surface and overflows while
heavy materials sink. This process has been used to process the air
classified, heavy portion of raw refuse, separating wood, textiles, rubber,
leather, and plastics from glass, aluminum, and other nonferrous metals. This
process has also been used to recover a high-grade metal concentrate from
scrap automobile shredder rejects (i.e., the nonmagnetic fraction from
shredding junk autos).
Heavy media separation—Heavy media separation utilizing fluids with
specific gravities greater than 1 have been demonstrated to separate aluminum
from heavy nonferrous metals in raw refuse and combustor residue.
Commercial recovery of aluminum has been achieved with heavy media separation
using suspensions of ferrosilicon, magnetite, or galena.
Eddv-current separation--Eddv-current separation is a dry separation
process based on the principle that an electromagnetic field passed through
nonferrous metals induces eddy currents in the metals which interact (or
3-8
-------
counteract) with the magnetic field. These interactions exert a repelling
force on the metals, separating them from the fields. Devices based on
eddy-current separation have been demonstrated to recover a nonferrous metal
fraction from raw refuse.
Electrostatic separation--Electrostatic separation devices use an
electrically grounded rotating drum and one or more electrodes. As feed
materials enter the electrostatic field generated by the electrodes, the
individual particles are charged. Conductors, including metal and paper,
immediately lose their charge and are repelled by the grounded drum.
Nonconductors, including glass, plastics, rubber, bone, wood, textiles and
ceramics behave as nonconductors and remain pinned to the drum. This process
has been demonstrated to recover aluminum and other nonferrous metals from
municipal refuse.
3.2.1.3 Separation Techniques for Glass.
J i qq i nq/screeni nq--J i qq i nq separates glass and aluminum from nonferrous'
fractions in raw refuse and combustor residue. Glass is subsequently
separated from aluminum by passing the mixture through a roll crusher which
pulverizes the glass and flattens the aluminum, followed by screening to
separate the two materials.
Froth flotation — Froth flotation is a technique using differences in the
chemical properties of finely ground glass and contaminants to achieve
material separation. The glass and contaminants are mixed with a
physicochemical reagent, which adsorb preferentially to the glass surface
glass. The coated glass attaches to bubbles formed by agitating the mixture
with air and is swept off the top. This process is generally performed in a
series of froth flotation cells.16
Optical sorting—Optical sorting is a process designed to remove foreign
materials from glass fractions and to separate glass by color. The process
employs a series of photocells which separate the opaque particles from the
transparent particles by matching the intensity of light transmitted through
the particles with a fixed-shade background.
3.2.1.4 Separation Techniques for Paper.
Manual sorting—Prior to shredding municipal waste for resource recovery
processing, large items that could potentially damage the shredding equipment
are removed. In conjunction with this step, sorting personnel may also be
3-9
-------
instructed to remove newspaper and corrugated boxes from the raw refuse.
These materials are relatively easy to remove and may be sold directly to
waste paper dealers.
Mr classification—After shredding, the first step in most materials
recovery processes is to air classify the mixed waste into a lighter, mainly
organic fraction and a heavier, mainly inorganic fraction. The light fraction
consists primarily of paper and plastic. The heavy fraction may be further
air classified to remove any remaining paper.
Electrostatic separation--Electrostatic separation, as described
previously, has been demonstrated to separate paper and plastic from air
classification streams.
3.2.2 Description of Commercial CentralizedProcessing Systems
17 18
3.2.2.1 Sorain-Cecchini System ' --The Sorain-Cecchini system,
developed about 20 years ago, automatically processes municipal waste into ~
recyclable fractions (Figure 3-1). The system further upgrades these
materials into marketable products, including aluminum and ferrous scrap,
baled cardboard, polyethylene pellets, paper pulp, soil conditioner (i.e.,
compost) and ecological fuel. Fourteen plants using the Sorain-Cecchini
process are under construction or operating presently worldwide. Locations
include Italy, Brazil, Japan, Canada, Equador, Norway, Yugoslavia and
Czechoslovakia. In addition, feasibility studies have been performed for
construction of additional facilities using the Sorain-Cecchini process in the
United States, England, Holland, Venezuela, Soviet Union, and numerous other
countries. The Sorain-Cecchini system processes waste through a series of dry
primary and secondary separating operations to segregate the following
fractions: ferrous metals, aluminum, film plastic, organics, and densified
refuse derived fuel (DRDF). The recovered organics fraction consists of hard
plastics, organics, glass, ceramics, sand, and ashes. This system can also
recover paper as cardboard and pulp. Also, the recovered organics fraction
can be processed as animal feed, high grade compost, and low grade compost.
The incoming waste is sorted to remove over-sized pieces and waste that
cannot be processed. The remaining waste is passed through a leveling device
and a primary screen which separates the large fraction (nominal 8 in.),
3-10
-------
consisting mainly of paper, wood, and film plastic from the small, heavier
fraction, consisting mainly of organics, glass, ceramics, metal, sand, and
ashes.
Both the large and small fractions from the primary screen undergo a
series of classification steps, each producing a light and heavy fraction.
These fractions are further processed into like fractions and distributed to
recover lines where materials are processed into a marketable form.
Ferrous metals are recovered by magnetic separation at three points in
the waste recovery process. The recovered ferrous fractions are fed to a
specially designed hammermill which cleans the ferrous fraction through
friction and densifies it through compression. A final magnetic separator
separates the ferrous metals from the nonmetals loosened by the hammermill.
Following ferrous recovery, the heavy fractions are processed by eddy current
separation to recover aluminum. The aluminum fraction is crushed to densify
the material and to reduce voids.
Paper is separated by a series of air classification steps from plastic
and other heavier materials and is either processed into DRDF or paper pulp.
After densification, the DRDF is sold or used as fuel on-site. The recovered
plastics fraction is shredded, washed, dried, and processed into pellets.
Organic fractions, consisting of small organics, glass, ceramics, sand,
ashes, hard plastic, small pieces of wood, and some of the smaller heavier
materials which are otherwise being recovered, are separated at several points
in the waste recovery process. These fractions are processed into a raw
compost in an aerobic digester and then cleaned to remove inorganic materials.
The remaining organics fraction may be further processed to make animal feed
or commercial compost.
19
3.2.2.2 Stardust '80 Stardust '80 is a comprehensive, multi-purpose
resource recovery system developed by the Japanese government. The system
features processes for sorting mixed waste into components from which compost,
pulp, fuel gas and oil, and light-weight aggregate may be recovered. The
system is currently in operation in Tokyo and Yokohama.
3-11
-------
i
rv>
Small
Fraction
i
Magnetic
Separation
I
Screening
I
Air
Classification
Mixed
Waste
Removal of
Oversized Objects
. Large
Fraction
Air
Classification
Differential
Shredder/
Rotary Screen
Figure 3-1. Separation Steps in Sorain - Cecchini Process
-------
At the Yokohama plant, incoming refuse is separated by a semi-wet
pulverizing classifier into three primary fractions: garbage, paper, and
plastics. Before 1981, the garbage fraction underwent further processing to
separate glass and dirt, before being converted to refined compost by a high
rate composting system. The glass and dirt removed was subsequently processed
into light-weight aggregate. The paper fraction was air assified and then
further processed to recover refined pulp. The plastics fraction was passed
through a magnetic separator to recover ferrous metal, shredded and then
processed into fuel gas (heating value - 620 Btu/scf) by a two-bed pyrolizer.
In 1981, a high rate fermentation system was added to convert the garbage
fraction into methane with a heating value of 650 Btu/scf.
At the Tokyo plant, only the paper and plastics fractions separated from
incoming refuse are further processed on-site. The paper-plastics fraction
recovered at the Tokyo plant is processed through a fluidized bed pyrolysis
oil recovery system into fuel oil having a heating value of 14,400 Btu/lb and
a solid fuel with a heating value of 6,660 Btu/lb.
Developers of the system emphasize that different combinations of the
recovery processes demonstrated at the Yokohama and Tokyo plants may be used
at other locations depending on site-specific needs. For example, the
composting process is recommended for facilities in cities with large
populations where refuse typically has a higher proportion of garbage.
Garbage is more difficult to incinerate than other refuse types. Likewise,
methane fermentation systems are recommended when municipal waste and sewage
treatment efforts can be combined. A flow diagram (Figure 2) illustrates the
basic recovery process operations offered by the Stardust '80 system.
3.2.2.3 ORFA Process A recent development in centralized waste
processing is the ORFA process. A prototype facility utilizing this process
has been operating in Switzerland for the past 3 years. Plans are currently
underway to construct commercial facilities based on the ORFA process in the
United States. The ORFA process converts municipal refuse into three
marketable fractions. The first fraction, ORFA fiber, is a sanitized and
stabilized fibrous material composed mainly of cellulose. Its expected uses
include feedstock for agricultural products and pulp and paper, and in energy
3-13
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Lightweight
Aggregates
Glass and Dirt
Separation
High-rate
Composting
High-rate
Fermentation
Mixed
Waste
±
Classification
Refined Pulp
Recovery
C Methane j
T
I
1
1
1
f
Pyrolysls OH
Recovery
T
l
L >.
Magnetic
Separation
Pyrolysls Gas
Recovery
Optional Process
• Routes
Figure 3 - 2. Optional Recovery Processes Available In Stardust 80 System
-------
and building materials industries. The second fraction, Granulite, is a
composite of plastics, glass, nonferrous metals, sand, dust, grit, and other
heavy materials, and is intended for use in building materials and road repair
applications. The third fraction, a ferrous metal fraction, is shredded for
sale to scrap metal dealers. The primary recovery steps in the ORFA process
include size reduction and ferrous metal removal followed by drying,
stabilization, and sanitization by ozone. The remaining processed waste is
then separated into ORFA fiber and Granulite by a series of size and density
classification steps. To reduce odorous emissions from the various process
steps, exhaust gases are vented to a bio-filter which traps odorants and
neutralizes them by aerobic digestion.
3-15
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3.3 REFERENCES
1. Hertzberg, Richard. New Directions in Solid Waste and Recycling.
BioCycle, Vol. 27, January 1966. pp. 22-27.
2. Copeland, Vivian S. Recycling Success in Canada: 80% Participation!
Waste Age, Vol. 15, November 1984. pp. 38-42.
3. Salimando, Joe. Empire: Pioneers in Recycling. Waste Age, Vol. 17,
January 1986.
4. Pettit, C. L. Trends in Collecting Recyclables. Waste Age, Vol. 17,
June 1986.
5. Bronstein, Scott. Where, Oh, Where to Empty the Trash? The New York
Times. September 14, 1986. p. 6F.
6. Plastics Recycling: A Revival. Chemical Engineering, June 25, 1984.
pp. 22-26.
7. How To Recycle Waste Paper. Published by the American Paper Institute,
Paper Recycling Committee, 1985.
8. Transfer Center Serves Oregon Communities. Waste Age, Vol. 14,
December 1983. pp. 27-30.
9. Steisel, Norman, Paul D. Casowitz, and Joan Edwards. A Status Report on
Materials Recycling Activities in New York City. The City of New York
Department of Sanitation. December 1985.
10. Cotter, Daniel A. San Francisco's Integrated Recycling Program.
Proceedings of the Twelfth Biennial Conference, 1986 Waste Processing
Conference. ASME. Denver, Colorado. June 1-4, 1986.
11. Franklin Associates, Ltd. Characterization of Municipal Solid Waste in
the United States, 1960 to 2000. Final Report. EPA Contract 68-01-7037,
Work Assignment 349. July 1986.
12. Transfer Station Designed for Maximum Recycling. World Wastes, Vol. 26,
April 1983.
13. Bernheisel, J. F. Materials Recovery Systems. Resource Recovery and
Utilization, ASTM STP 592, American Society for Testing and Materials,
1975, pp. 64-70.
14. Mahoney, Patrick F. There's Gold in That There Ash! Waste Age, Vol. 17,
April 1986.
3-16
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15. Makar, H. V. and R. S. DeCesare. Unit Operations for Nonferrous Metals
Recovery. Resource Recovery and Utilization, ASTM STP 592, American
Society for Testing and Materials, 1975, pp. 71-88.
16. Archer, Tom and Jon Juls. RCRA Study of Glass and Plastic Resource
Recovery. Proceedings of the Seventh Annual Research Symposium,
EPA600/9-81-002C. March 1981.
17. Cashin, Francis J. and Pretio Carrera. The Sorain Cecchini System for
Material Resource Recovery. Proceedings of the Twelfth Biennial
Conference, 1986 Waste Proc^sing Conference. ASME. Denver, Coloraoo.
June 1-4, 1986.
18. KLES Incorporated. Energy and Materials from MSW - Sorain Cecchini. No
date.
19. Stardust '80: Putting Refuse to Work. Agency of Industrial Science and
Technology MITI (Japan). No date.
20. Introduction to the ORFA Process and ORFA Corporation of America. ORFA
Corporation of America. September 1986.
3-17
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4. MATERIALS AND MARKETS
This section presents information on the separation feasibility and
marketability of individual municipal waste constituents. The municipal waste
components covered in this section include: aluminum, ferrous metals, glass,
paper, plastics, wood, rubber and organics. Techniques currently used or
under development to separate each of these components from municipal waste
for recycling are identified. Current and potential markets for recovered
materials in the United States are described.
4.1 ALUMINUM
Aluminum recycling in the United States has been very successful. In
fact, it has been so successful that Reynolds Metals found it advantageous to
solicit recycled aluminum in the United States rather than continue alumina
and bauxite production overseas. A further indication of aluminum recycling's
success is found in U.S. Bureau of Mines statistics showing 32 percent of U.S.
consumption of aluminum in 1982 was recycled aluminum.
In 1984, approximately 1.5 million tons of aluminum was discarded with
municipal waste. Although steadily increasing, the tonnage of aluminum
discarded is small. About 643,000 tons of aluminum were recovered in 1984
from discarded containers and packaging. The recovered aluminum containers
were then used to make sheet for new cans. Recovery of aluminum waste is
expected to continue to grow slowly with the increased demand for aluminum
cans. The percent recovery is expected to stabilize at about 50 percent of
the cans in the total municipal waste stream. The amount of aluminum
recycled may have little effect on landfill space, but revenues generated from
the sale of aluminum waste are high and help to offset other waste handling
and recycling costs.
Source separation has been a major method of separation of aluminum cans
and packaging from the municipal waste stream. In addition, several
separation processes for recovering aluminum scrap from mixed refuse have been
described. Eddy current separation has demonstrated 70 to 80 percent
recovery of aluminum from mixed refuse. '
4-1
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4.2 FERROUS METALS
Discarded ferrous metals totalled about 11 million tons in 1984. Of the
11 million tons, about 2.9 million is estimated to be steel packaging (cans,
pails, buckets, drums). Steel once accounted for all beverage cans but has
been largely supplanted by aluminum. The percent decline in the proportion of
ferrous materials in municipal waste is expected to continue.
Ferrous metals are easily removed magnetically from mixed municipal waste.
Centralized separation processes typically include an operation for separating
shredded ferrous scrap. Combustion operations may separate ferrous
materials before combustion or after combustion, when the metal has been
sterilized. Even though ferrous scrap is one of the easily separated constituents c
mixed refuse stream, it is not an intensively recycled part of municipal
refuse. Franklin Associates reports a continuing decline in quantities
recycled, because other sources of high quality ferrous scrap are available to
secondary ferrous metal producers. This, coupled with declining demand for'
steel, means that ferrous scrap recovered from municipal waste is marginal in
the marketplace.
One of the major technical problems associated with recycling steel
packaging can be overcome through detinning processes that remove tin from the
scrap, thereby producing a high quality scrap and increasing its utility for
use by secondary metals producers. An optimum scheme for recovery of
ferrous materials is the separation of steel cans from unburned refuse after
Q
shredding, followed by detinning to recover the tin. The scrap can then be
further shredded or compacted to make a premium scrap.
While the market for shredded ferrous scrap recovered from
municipal waste does not look favorable nationally, local market conditions
may make recovery economically feasible. Location of municipal waste recovery
facilities near detinning or copper mining operations may capitalize on good
local market potential. For example, New York City, in developing its
recycling strategy, found one market for steel cans in the local area - a
Q
detinning facility in New Jersey. The largest use of recycled tin cans is in
refining copper ore. For ores rich in oxides, a leaching process based on a
copper-iron ion exchange is used with cans as a source of iron. The demand
for cans to be used in this process is localized in Arizona and Utah.
4-2
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4.3 GLASS
Glass accounted for an estimated 14 million tons of waste generated in
the United States in 1984, or about 9 percent by weight of the total municipal
solid waste generated. The proportion of glass in the waste stream peaked in
the early 1980's at 11 percent. Over the past 5 years, glass containers have
lost considerable market share to aluminum and plastic containers. The trend
is expected to continue and by the year 2000, the percentage of glass in the
2
waste stream is projected to fall below 8 percent.
In 1984, about 1.0 million tons of glass was recovered for reuse.
Virtually all of the recovered glass was in the form of glass containers
(i.e., beer and soft drink containers, wine and liquor bottles, food bottles
and jars, etc.). The primary market for recycled glass containers is the
glass container manufacturing industry. Glass manufacturers can replace at
least 50 percent of their raw materials with cullet derived from recycled
glass containers and from scrap cullet (i.e., in-house scrap or scrap
purchased from bottling plants). However, to be suitable for use by the glass
manufacturing industry, cullet from recycled glass containers must be
separated by color (i.e., clear, amber, and green) and be relatively free of
contaminants such as paper, plastic, metals, and rocks. Strict quality
specifications are maintained by the glass manufacturing industry for recycled
11 12
cullet. ' For these reasons, and because raw materials for making glass
are relatively inexpensive, most glass manufacturers use no more than 20
percent cullet in their glass batches.
Other markets for recycled glass which have less stringent quality
requirements include manufacturers of glass wool and certain building and
14 15
paving materials. ' Many of these markets can accept mixed-color cullet
with relatively high levels of contaminants. Consumption of recycled glass
by these markets, however, is minimal at present. Efforts to develop more
fully these and other markets for used glass by experimental production and
testing of materials made from recycled glass are being undertaken by the
Bureau of Mines.
4-3
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Glass containers are recovered for reuse in three ways: source
separation, mechanical separation, and reuse programs. Source separation
accounts for the majority of recovered glass containers. Some processing is
typically required to sort the collected bottles by color and to remove
contaminants before the recovered glass can be turned into cullet for reuse by
the glass industry. These processing steps have traditionally been performed
manually. Recently, mechanical processes have been developed to process
".dirty" glass. Also, processes relying on optical sorting of mixed-color
glass into single-color glass fractions have been demonstrated. ' In
general, though, processing of glass into clean, single-color components is
likely to continue to be a labor-intensive process.
Mechanical separation of glass from mixed municipal waste for purposes of
resource recovery, or to enhance the fuel quality of the residual waste, is
practiced by a number of facilities. The glass fraction recovered by these
processes is generally not suitable for use by the glass container
manufacturing industry because it is mixed-color and has a relatively high
12
level of contaminants. Instead, the recovered glass fraction may be used in
production of various building materials, as an aggregate in paving and
construction projects, or as landfill. ' ' Mechanical separation of glass
usually is achieved by a series of classification and separation steps to form
a glass-rich fraction which is then subjected to froth flotation to
13 19
concentrate the glass further. '
Reuse programs rely primarily on container deposit legislation requiring
consumers to pay a deposit on beverage containers which is redeemed when the
containers are returned to the retailer. Nine states have passed returnable
container deposit laws (Section 3.1.1). An additional twenty-three states
20
reportedly are considering similar legislation. Bottles collected as a
result of these laws have the advantage of being easily color-separated by
redemption centers, thereby facilitating their processing for reuse by the
glass container manufacturing industry. The impact of container deposit laws
on overall recycling efforts is uncertain. Although these laws have been
effective in diverting up to 90 percent of discarded glass containers from
4-4
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municipal waste, they have resulted in consumers switching to containers that
21
are more convenient to handle (e.g., plastic and aluminum). Further, they
22
have created flooded markets for some types of glass cullet. In New York
City, for example, availability of green cullet primarily from imported beer
bottles has increased significantly and exceeds current market demand for
green glass. In general, the increased availability of glass cullet from
container deposit laws tends to drive down the price for green and amber
9
cullet but has little effect on ?ar (i.e., flint) cullet. The net result
is that privately owned recycling businesses which are no longer able to
collect ^d process glass (and aluminum) containers profitably may decline,
21
thus reducing recycling efforts for other materials.
4.4 PAPER
Waste paper and paperboard is the single largest component of municipal
waste, accounting for an estimated 37 percent by weight of total municipal
waste generated in 1984. Of the approximately 62.3 million tons of paper and
paperboard waste generated in 1984, an estimated 13 million tons, or 21
percent, was recovered for reuse. Both the total amount of waste paper
generated and the amount recycled are expected to increase slowly over the
2
next few years.
Most of the recovered paper and paperboard ^n the United States is reused
by the paper and paperboard manufacturing industry. Of the 600 paper and
paperboard mills in the United States, 200 depend exclusively on waste paper
for raw material and another 300 mills use a percentage of waste paper as
23
their raw material. To make use of recycled fiber, paper and paperboard
mills require special equipment and facilities to perform pulping, cleaning,
f\ *
screening, and refining operations needed to prepare recycled fiber-stock.
Before recovered waste paper can be used by the paper industry, steps must be
taken to remove contaminants introduced during production and fabrication of
paper products or during the use of those products. Example of contaminants
introduced during production and fabrication include: non-emulsifiable
latexes; plastics laminated to paper; wet strength resins; nondeinkable inks,
hot metals in bindings; waxes, resins and other polymers for special products;
chemical additives; pressure sensitive tapes for sealing; heat seal labels;
4-5
-------
and some paper coatings. Dirt, food, metal, rags, wire, glass, and plastics
25 ?6
are examples of waste paper contaminants introduced during use. ' The
ability to use various grades of waste paper to replace virgin raw materials
depends on the type of paper being manufactured. For example, mills that
produce business printing and tissue paper can utilize only the highest
quality grades of waste paper. Examples of these include scrap from
paper-converting plants and data processing centers, ledger paper from
offices, and printed bleached paper that has been processed at a deinking
mill. Bulk grades of waste paper, including recycled newspaper, corrugated
boxes, and mixed office waste paper, are used by mills that make newsprint,
g
paper board, and construction paper.
Source separation is the most prevalent method of recovery of waste paper
for reuse by paper and paperboard mills. Most notably, source separation is
used to recover newspaper, corrugated boxes, and high grade office paper.
Newspaper is particularly well suited for recycling because a competitive
market for used newspaper exists and because it comprises a significant enough
portion of the municipal waste stream to afford appreciable landfill savings
22
when recycled. Approximately 3.3 million tons of newspaper was recycled in
P
1984 corresponding to abou* 24 percent of the discarded newspapers.
Newspaper collected by residential source separation programs is typically
sold to a waste paper dealer who processes the paper by removing contaminants
and densifying for bulk resale to paper mills. Major markets for used
newspaper are mills producing boxboard or newsprint and producers of
specialized construction and building materials.25'26
Used corrugated boxes are the largest single source of waste paper for
recycling. In 1984, an estimated 6.8 million tons, or about 36 percent, of
used corrugated boxes were recycled.2 As with paper dealers handling used
newspaper, used corrugated cardboard dealers manually remove contaminants from
the recovered corrugated boxes and perform any additional processing required
by paper mills purchasing the used corrugated paper. Major markets for used
corrugated boxes are paperboard mills and producers of specialized
construction and building materials.9'26
4-6
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Current programs to recycle high grade office paper are motivated by the
relatively high value of these materials in the waste paper market. Dealers
typically pay more for high grade office paper than for bulk grades of waste
paper, such as newspaper and used corrugated boxes, because of the capabi,;ty
of paper mills to use the waste paper as a direct substitute for wood pulp in
Q
the papermaking process. Recycling programs have been established in a
growing number of office buildings to recover the value of their high grade
waste paper. In 1984, about 800,000 tons (16 percent) of high grade office
2
paper waste were recycled.
Waste paper recovered mechanically from mixed municipal waste generally
does not meet industry specifications for use by paper mills in the
United States, although some paper mills have indicated their willingness to
use waste corrugated boxes and mixed paper recovered from mixed waste that is
26
predominantly commercial or office waste. However, in most cases, the paper
industry would require waste paper recovered from a mixed waste .stream to
undergo extensive cleaning and sterilization before it could be used to make
even low-grade paperboard. Other markets with less stringent quality
requirements for recovered waste paper from mixed waste streams include
manufacturers of cellulose insulation, packing and cushioning materials, and
23
building products. These markets can accept the lowest grades of waste
26
paper and are an outlet for otherwise unusable paper fiber. Although
consumption of waste paper by these markets at present is limited, development
of these and other markets for mixed waste paper is considered an important
factor toward increasing significantly the amounts of waste paper that can be
27
economically recycled and reused in the future.
Most of the waste paper recovered in the United States is consumed in
U.S. paper mills. In 1984, however, an estimated 3.4 million tons of waste
23
paper was exported for use as raw material in foreign paper mills.
Estimates of future exports of waste paper are favorable in light of projected
shortages of indigenous forest resources in Europe, Japan, and other parts of
Asia. Cities like New York City are depending on the expansion of foreign
markets to help absorb the waste paper collected under their comprehensive
q
recycling programs.
4-7
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4.5 PLASTICS
Approximately 9.7 million tons of plastic waste was generated in the
United States in 1984, representing about 6.5 percent by weight of the total
generated municipal waste. Of the total plastic wastes generated, plastic
containers and packaging make up the largest fraction, accounting for over
half of plastic discards in 1984. The amount of plastic waste discarded
annually has more than doubled since 1960 and, while still a small fraction,
plastics is currently the most rapidly growing material in the solid waste
stream. By the year 2000, discarded plastic containers and packaging alone
are projected to represent more than 5 percent by weight of the total waste
2
stream.
Recycling of post-consumer plastic waste is currently not a common
practice. In 1984, less than 100,000 tons of post-consumer plastic was
2
estimated to be recycled. However, one type of plastic waste is currently *
the focus of a limited but successful recycling effort. Polyethylene
terephthalate (PET), most commonly used in 2-liter soft drink containers, is
currently being recovered and reused in a variety of applications. In 1984,
an estimated 63,000 tons of PET containers, or about 18 percent of the total
PET containers discarded, was recycled. The primary source of PET containers
2
for recycling was states with container deposit laws. The principal market
for recycled PET is polyester fiber staple, used in clothing, pillows or other
items, or for glass-fiber products. Plastic strapping for pallet wrapping is
another use for recycled PET, but this market is small (5 to 18 million pounds
28
per year). Methods are also under development to convert PET to polyols for
•ise in rigid or flexible urethane foams.
The FDA regulations for food packaging materials preclude reuse of
recycled PET to make new soft-drink containers. ' Different processes are
used by intermediate dealers to process soft-drink containers for PET recycle.
These containers typically contain several components in addition to PET,
including a high-density polyethylene (HOPE) base cup, paper or paint labels,
and an aluminum and/or plastic cap. Some processors separate these materials
by first removing the cap and base cup (manually or mechanically), grinding
the remaining material, and then washing the ground PET to remove paper and
adhesive. Another system first grinds the whole bottles and then passes the
4-8
-------
ground materials through an air classifier to remove paper, an electrostatic
precipitator to remove aluminum, and a flotation system to separate plastic
resins. Both methods are reported to be capable of supplying high purity
° Also, the recovered HOPE may be sold to plastic scrap users for
production of flower pots, plastic tubing and other products as well as for
29
the manufacture of new base cups. Recycling of PET containers is expected
to continue to increase as additional states pass container deposit laws, and
as additional uses for recycled DJT are identified.
Several factors contribute to the overall low level of post-consumer
plastics recycling. Technologies for removal of contaminants in the form of
metal, paper, wood, ceramic, and other substances which have been integrated
into plastic products have been slow to develop. ' Further, to recycle
more post-consumer plastic wastes, the majority of which consist of multiple
resins, further technological development is needed for processes that
segregate plastic resins into homogeneous groupings or for end uses which can
utilize mixed resin scrap. Processes that separate mixed plastic wastes into
recyclable fractions or that use mixed resin scrap for manufacturing new
931
plastic products are practiced on a limited scale at present. For
example, the Sorain-Cecchini process described in Section 3.2.2 is capable of
separating and recovering so-called film plastic (i.e., low density
polyethylene) from other plastic waste by a series of air classification
steps. The recovered film plastic is either baled and sold to the injection
and compression molding plastic industry or formed into pellets and combined
with 5 to 10 percent of virgin materials to make new film plastic. The
remaining plastic wastes (i.e., PVC, PET) are not currently salvaged by this
32
process, but some could be recovered through source separation.
One suggestion for improving the ability to recycle plastic products is
to require manufacturers to label clearly plastic products so that the
consumer could identify easily the type(s) of resin contained in the plastic
product. This would facilitate recycling of plastic waste by source
separation because the consumer would be able to segregate plastic waste into
single-resin components.
4-9
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Emphasis has also been placed on developing techniques for processing
recovered mixed plastic waste into a reusable form. One process in use is the
Reverzer process, developed by Mitsubishi Petrochemical in Japan, which
utilizes mixed thermoplastic wastes with up to 20 percent non-thermoplastic
materials (e.g., paper) to make extruded and molded plastics products with
thick cross sections. These products include fence stakes, irrigation pipe,
pallets, part benches, road drains, cable drums and building panels. At least
30 companies worldwide reportedly are using this technology to make plastic
products. Other processes include: (1) the Japan Synthetic Paper process
which compression molds film scrap (from mixed plastics) with wood chips to
make chip/wall board, and (2) the Regal Packaging process which first
granulates mixed plastic wastes and then fuses the granules with heat into
sheets used in compression molding to produce a variety of plastic products.
The latter technology is reportedly capable of handling plastics with paper,
metal, glass, and sand contamination.
4.6 WOOD
Discarded wood wastes comprised to about 5.1 million tons in 1984. Wood
waste removed from the waste stream reportedly has been sold as wood chips for
34
firing boilers. Waste wood recovered from refuse also has been used to make
34 35
paper pulp. '
In San Francisco, wood is reported to be separated by hand from
construction delivery boxes. After the wood passes through a hammer mill and
grinder, the wood chips are sold for boiler fuel. Tree branches from city
parks and from tree pruning companies are also processed in this way by two
companies that began work in 1984. Recycling wood from construction waste in
this manner results in a significant reduction in wood waste to be landfilled
and is reported to be a lower cost alternative to landfilling.
4.7 RUBBER
Gross discards of rubber products in 1984 comprised 1.9 million tons, of
which 1.2 million tons were tires and tire products. Tonnage of discarded
rubber tires has been declining with decreasing car sales and the advent of
smaller and more durable tires. Small growth in discards is anticipated as
4-10
-------
2
car sales increase with the increase in number of people of driving age.
Recovery of tires for reuse or recycling accounted for 5.2 percent of discards
in 1984, down from 20 percent in 1960. Thirty-three thousand tons of tires
was retread in 1984, and rubber recovery for other uses amounted to 103,000
?
tons.
Recycling options for rubber tires include retreading and rubberized
asphalt. Rubber asphalt mixtures have been demonstrated in Arizona to
extend substantially pavement life and reduce the amount of resurfacing
42
required. The Danish government is reportedly considering using discarded
38 9
tires in highway asphalt , as is the city of New York. However, analysts
have not seen an optimistic future for recycling rubber products.
Tire disposal presents problems because landfill ing is an inefficient use
of landfill space, and tires are non-biodegradable. Air trapped in tire rims
causes the tires to rise to the surface. Burning tires in regular combustion
equipment can cause high levels of sulfur emissions and black, sooty-laden
smoke. Many old tires are stacked outdoors where they can harbor rodents and
43
insects. Shredding is one procedure that can reduce the volume required in
landfill ing. New York City is currently using shredded tires as a part of
40
their daily landfill cover. Combustion of shredded rubber or whole tires in
specially designed equipment as a cheap energy source is receiving attention
as a disposal method, thus reducing required landfill space and recovering
energy.16'37
4.8 COMPOST
Quantities of disposed yard waste are poorly documented and vary widely
across the United States. Disposed yard waste was estimated in 1984 to be
23.8 million tons. Some yard waste is composted but the quantity is not known
2
and is expected to be small compared to the total waste stream.
There are reportedly numerous composting facilities in rural Germany.38
Markets for compost exist in Rhineland vineyards, gardens, parks, and
orchards. In the United States, the city of San Francisco has established
production of compost from zoo animal bedding and manure. The composted
materials is marketed commercially as "Zoo Doo." San Francisco is also
reportedly planning composting for tree trimmings, leaf litter, and grass
clippings from Golden Gate Park for use on city parks and golf courses.
4-11
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In New York City, low grade compost is being used as landfill cover.
This measure is a volume reduction measure because cover material consumes
39
about 70 percent of available landfill volume. Compost is also being
produced in Berkeley, California in a centralized city compost facility.
Producing a refuse material for composting requires several processing
steps aimed at reducing the size of the refuse components and separating
compostable materials from other materials. One recommended system ncludes
the following steps: 1) shredding, 2) magnetic separation of ferrous
materials, 3) air classification to remove a large portion of heavy
inorganics, and 4) screening to removal grit, glass, and small hard
particles.44
4-12
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4.9 REFERENCES
1. Cutter, Susan. Resource Recovery, An Overview in Environmental Policy:
Solid Wastes. Volume IV. Ballinger Publishing Company, Cambridge,
Massachusetts. 1985.
2. Franklin Associates, Ltd. Characterization of Municipal Solid Waste in
the United States, 1960 to 2000. Final Report. EPA Contract 68-01-7037,
Work Assignment 349. July 1986.
1. Pettit, C. L. Trends in Collecting Recyclables. Waste Age. Vol 17, No.
" July 1986. pp 49-56.
4. Makar, H.V. and R.S. DeCesare. Unit Operations for Nonferrous Metals
Recovery. Resource Recovery and Utilization, ASTM STP 592, American
Society for Testing and Materials, 1975, pp 71-88.
5. Kenny, Garry, and Edward J. Sommer, Jr. A Simplified Process for Metals
and Noncombustible Separation from MSW Prior to Waste-to-Energy
Conversion. ASME Meeting, Orlando, Florida. June 3-6, 1984.
6. Interrant, C.G. Report on the Ferrous Metals Workshop in Resource
Recovery and Utilization, ASTM STP 592, American Society for Testing and
Materials, 1975, pp. 146-152.
7. Groetsch, J.G., Jr., R.C. Gabler, Jr., and D.A. Wilson. Electrostatics
stripping of Tin in an Acid Fluoroborate Electrolyte. Report of
Investigations 8887. U.S. Department of the Interior. 1984.
8. Kaplan, R.S. Deterrents to the Recycling of Ferrous Scrap from Urban
Refuse in Resource Recovery and Utilization, ASTM STP 592, American
Society for Testing and Materials, 1975, pp. 91-105.
9. The Waste Disposal Problem in New York City: A Proposal for Action.
Volume 7: Recycling Strategies. Supplement to Preliminary Planning
Report Submitted to the Board of Estimate in April 1984 by the Department
of Sanitation in Response to a Resolution (Calendar No. 87) Adopted by
the Board on June 16, 1983.
10. Miller, Robert E. and Oscar E. Dickerson. Management of Solid Waste in
Cold Regions: Resource Recovery Potential in Proceedings of Third
Symposium on Utilities Delivery in Cold Regions. May 25-26, 1982.
11. Scientific Energy and Recycling Group, Inc. Resource Recovery:
Experience and Systems Description, [no date]
12. Seeley, C.E. Glass in Solid Waste Recovery System: Resource Recovery and
Utilization, ASTM STP 592, American Society for Testing and Materials,
1975, pp. 114-121.
4-13
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13. Archer, Tom and Jon Juls. RCRA Study of Glass and Plastic Resource
Recovery. Proceedings of the Seventh Annual Research Symposium,
EPA-600/9-81-002C. March 1981.
14. Scott, Pickett. Report on the Glass Workshop. Resource Recovery and
Utilization, ASTM SIP 592, American Society for Testing and Materials,
1987, pp. 159-164.
15. Stanczyk, Martin H. and Roger S. DeCesare. Resource Recovery from
Municipal Solid Waste. U.S. Department of Interior: Bureaus of Mines.
Bulletin 683 1985.
16. Bronstein, Scott. Where, Oh, Mere to Empty the Trash? The New York
Times. September 14, 1986 p. 6F
17. Boyhan, George E. and S. Sengupta, eds. Waste Disposal and Resources
Recovery. (Dade County), Inc. in 2nd Conference on Management of
Municipal, Hazardous & Coal Wastes: Proceedings. Resource Recovery,
Inc. Miami University, Miami, Florida. September 1984.
18. Mahoney, Ps:rick F. There's Gold in That There Ash! Waste Age, Vol. 17,
April 1986.
19. Marsh, Paul. Recycling: Glass in Kirk-Othmer, Concise Encyclopedia of
Industrial Technology. John Wiley & Sons, New York. 1985.
20. Plastics Recycling: A Revival. Chemical Engineering. June 25, 1984.
pp. 22-26.
21. Clapham, W.B. An Analyses of the Potential Effect of Beverage Container
Deposit Legislation on Municipal Recycling Programs. Journal of
Environmental Systems Vol 14, 1984-85.
22. Five Perspectives on a Hot Topic. Waste Age. Vol 17, No. 7, July 1986.
pp. 29-37.
23. Twelve Facts About Waste Paper Recycling. Distributed by the American
Paper Institute - Paper Recycling Committee. 1985.
24. Robins, James H. and James R. Grant. Recycling: Paper. Kirk-Othmer,
Concise Encyclopedia of Industrial Technology. John Wiley i Sons,
New York, 1985.
25. How to Recycle Waste Paper. Distributed by the American Paper Institute
- Paper Recycling Committee. 1985.
26. Arnold E. W. Report on the Paper Workshop. Resource Recovery and
Utilization. ASTM STP 592. American Society for Testing and Materials,
1985, pp. 177-184.
4-14
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27. Graminski, E. L. Problems and Potentials in Paper recycling. Resource
Recovery and Utilization, ASTM STP 592, American Society for Testing and
Materials. 1975 pp. 132-139.
28. Lipsky, Richard. The Collection, Processing Of, and Markets For, Post
Consumer PET, New York State Legislative Commission on Solid Waste
Management Conference on Materials Recycling and Composting. Albany,
New York. October 9, 1985 as cited in Hinchey, Maurice D., Chair. The
Economics of Recycling Municipal Waste. Staff report to New York State
Legislative Commission on Solid Waste Management. Albany, New York.
1986.
29. PET Plastic Recovery. Resource Recycling. Vol II, No. 1 March/
April 1983, pp. 17-19, 35.
30. Plastics Recycling. Viable Means of Energy Conservation. Resource
recovery Update. Vol 10, No. 5. May 1981.
31. Hellman, Eric. Plastics Recycling: Understanding the Opportunities.
Prepared for the Toronto Recycling Action Committee. December 1981.
32. KLES Incorporated. Sorain Cecchini: Energy and Materials from MWS.
No date.
33. Ingle, G.W. Report on the Plastics Workshop. Resource Recovery and
Utilization, ASTM STP 592, American Society for Testing and Materials,
1975, pp. 165-176.
34. Zerbe, John. Wood Products Laboratory. Telecon. Conversation with
G. E. Wilkins, August 25, 1986.
35. Carr, Wayne. Telecon. Conversation with G.E. Wilkins. August 27, 1986.
36. Cotter, Daniel A. San Francisco's Integrated Recycling Program in
Proceedings of the Twelfth Biennial Conference, 1986 Waste Processing
Conference. ASME. Denver, Colorado. June 1-4, 1986.
37. Goddard, Haynes C. Options for Resources Recovery and Disposal of Scrap
Tires: A Review of Technologies and Economics in Municipal Solid Waste
Resource Recovery in Proceedings of the Seventh Annual Research
Symposium, EPA600/9-81-002C. March 1981.
38. Hinchey, Maurice, Chairman New York State Legislative Commission on Solid
Waste Management in Norway, Sweden, Denmark, and Germany: Lessons for New
York. December 1985. Albany, NY.
39. A Status Report on Materials Recycling Activities in New York City. City
of New York Department of Sanitation. December 1985.
40. Taldone, Vincent. Telecon. Conversation with G.E. Wilkins, Radian
Corporation. September 8, 1986.
4-15
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41. Buchanan, Marc. Recycling Yard Waste in California in Biocycle. V. 25
No. 8 Jan-Feb. 1984. pp. 40-41.
42. Scrap Tires: A Resource and Technology Evaluation of Tire Pyrolysis and
Other Market Alternative Technologies. Idaho National Engineering
Laboratories. Idaho, 1983 as cited in Hinchey, Maurice D., Chair. The
Economics of Recycling Municipal Waste. Staff Report to New York State
Legislative Commission on Solid Waste Management. Albany, New York.
1986.
43. Berling, J. A Potential Public Health Problem Associated With Tire
Stockpiles. New York State Legislative Commission on Solid Waste
Management Conference on Materials Recycling and Composting. Albany,
New York. October 9, 1985 as cited in Hinchey., Maurice D., Chair. The
Economics of Recycling Municipal Waste. Staff Report to New York State
Legislative Commission on Solid Waste Management. Albany, New York.
1986.
44. Glaub, J.C., L.F. Diaz, and G.M. Savage. Preparing Municipal Solid Wa~ste
for Composting in Biocycle. V. 25, No. 8. Nov-Oec 1984. pp. 32-36.
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5. EFFECTS OF RECYCLING ON COMBUSTION
Because recycling is not expected to completely eliminate the need for
combustion, it is necessary to consider the effects of removal of recycled
materials on waste combustion. Test results show that combustion can reduce
the volume of waste by 60 to 90 percent. If a portion of the waste can be
removed and recycled prior to combustion, however, a 100 percent volume
reduction is possible. Therefore, the goal in both methods of waste management
is reducing landfill space required for waste disposal.
Waste constituents recycling can reduce combustion costs in three ways.
First, less combustion capacity is needed and smaller equipment usually
decrease construction costs. Second, combustor residue is decreased when
glass and metals are removed, thus lowering operating costs and tipping fees3.
Finally, maintenance cost savings may be realized if abrasive waste components
2
such as glass, metal and grit are removed.
Two types of effects of recycling on combustion will be considered
briefly in this section: 1) effects of materials removal on the combustion
process and 2) effects of materials removal on emissions from combustion.
Much of this section is based on logic and supposition. Little data were
found to determine what effect intensified recycling will have on
refuse combustion.
5.1 EFFECTS OF RECYCLING ON THE COMBUSTION PROCESS
When considering the effects of materials removal from the municipal
waste stream available for combustion, it is useful to identify two
categories of waste constituents, combustible and non-combustible, because the
combustion process acts only on the combustible portion to effect a volume
reduction. The non-combustible portion may also be changed chemically and
physically by the process and may affect the operation, but it is not actually
combusted.
aTipping fees are the fees charged by a waste handling facility to accept
waste.
5-1
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It appears logical that removal of non-combustibles would not adversely
affect the combustion process. Removal of significant quantities of metals,
glass and grit should, in fact, decrease slagging and clinker formation
through removal of substances that form slag and clinkers. Decreased slagging
and clinker formation should then, in turn, improve combustor on time
availability and improve overall combustor operations and performance.
Few data were found that could be used to affirm or deny this logic.
Data concerning combustion of processed waste such as RDF to unprocessed waste
are largely noncomparable because of differing combustor designs. However, a
series of tests run at a rotary combustor designed for mass firing was
performed to determine what effects non-combustibles removal has on energy
recovery from refuse. The tests showed removal of glass, grit, and metals
resulted in reduced clinker formation and slagging and improved combustor
availability of up to 40 percent; long-term availability was increased by 20
percent. The comparative tests of processed versus non-processed fuel also^
showed improved feed and ash handling, and steam generation rates were higher
and more consistent.
These few data would tend to support the logical deduction that removal
of non-combustibles from refuse may improve combustor performance. Other
benefits, as mentioned previously, include improved equipment life and the
ability to use smaller combustion equipment due to processing smaller
quantities of waste. Also, the remu/al of noncombustibles would tend to
increase the heating value of the waste, and therefore allow more efficient
combustion.
Removal of combustibles, on the other hand, would remove constituents
that support combustion, mostly paper. (Note: Yard waste is also combustible,
but is associated with so much moisture that :ombustion is poorly sustained.
Therefore, removal of yard waste or other wet organic waste would not
generally be considered detrimental to the combustion process.) It appears
that recycling efforts might compete for the fractions of the refuse needed by
the combustion process to reduce the volume of the remaining waste. For, if
Slag is rock-like mineral material formed by the melting and subsequent
solidification of ash in a furnace. A clinker is a large solidified mass of
slag material.
5-2
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a heat content high enough to sustain combustion is not maintained, the
addition of fossil fuel may be required to carry out the combustion process.
Addition of fuel would increase the cost of combustion.
According to Franklin Associates, municipal waste discarded nationwide in
1984 was composed of 37 percent paper and paperboard and 7 percent plastic
after current recycling. Assuming the paper fraction has a higher heating
value 'HHV) of 7,925 Btu/lb and the plastics fraction has a HHV of 11,708
Btu/lb and assuming the total w -te has a higher heating value of 4,50u
Btu/lb, it can be seen that in excess of 80 percent of the heating value may
be found in the plastics and paper in the waste available for combustion, with
most of it in the paper fraction.
Based on the previous discussion, paper is the combustible component
which would be most likely removed for recycling in the near future. For
purposes of combustion, paper is an important constituent in the waste. It is
estimated that about half of the wastepaper generated each year in the -
United States is not recyclable, either because the paper is too contaminated,
having been used in some way that precluded its recovery from the refuse
stream, or because it is uneconomical to collect. Even so, removal of half
the paper (using national average figures) and holding everything else
constant, would reduce the HHV of the waste to about 3750 Btu/lb, a reduction
in heating value of 17 percent. The value of 3750 Btu/lb is about the lower
limit of the value required to sustain and complete combustion for current
combustor designs. Though this heating value would likely still be sufficient
to support combustion, it may not be high enough to allow combustion practices
that minimize organic emissions to be achieved. Therefore, combustion of a
low heating value waste would probably require the addition of supplemental
fuel to meet guideline requirements.
Though removal of some combustibles may adversely affect combustion,
refuse and local market conditions are highly variable, and the effects of
removing paper or other combustibles from waste that is to be incinerated has
to be considered on the local level. The fact that recycling programs also
may include removal of noncombustibles must also be considered. For example,
in plans for solid waste management, Essex County in New Jersey analyzed the
effects of a planned materials recovery program on a planned combustor.
Essex County's analysis showed that in that particular situation, using
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specific Essex County waste characteristics, materials recovery was actually
predicted to increase the higher heating value of the waste, even with almost
complete removal of paper. Essex County found that the effects of removal of
paper tended to be offset by the removal of glass and metals which have no
heating value. Similar situations might be anticipated where RDF is being
produced for combustion, if recycling of paper is extensive before the waste
reaches the waste-to-energy facility.
The effects of recycling on the fuel value of incinerated waste have been
addressed by one major manufacturer of waste combustion equipment, Signal
Environmental Systems, Inc. According to this manufacturer, an all -
encompassing recycling program removing both combustibles and non-combustibles
should not appreciably alter the fuel value of the incoming waste. Under such
conditions, the removal of non-combustibles (i.e., glass, metal cans, etc.)
would have no effect on thermal efficiency, and on a per-ton basis, enough
paper should remain after recycling to maintain present levels of electricity
and steam production with no requirement for auxiliary fuel. One study
estimated that a newspaper recycling program achieving 25 percent
participation would reduce the fuel value of the remaining waste by only 2.8
2
percent.
5.2 EFFECTS OF RECYCLING ON EMISSIONS FROM COMBUSTION
Removal of non-combustibles from the refuse through recycling should
cause no increase in emissions to the atmosphere from combustion. Logically,
it would seem that removal of non-combustibles from the feed to the combustor
would decrease ash quantities to be disposed and particulate emissions. Also,
if the removal of metals and glass improves combustion conditions (Section
5.1), lower emissions of carbon monoxide and organic compounds would be
predicted. Results of tests at the previously mentioned Gallatin, Tennessee
facility tend to support this.
The Gallatin, Tennessee conclusion (Section 5.1) tests also showed
decreased lead and cadmium emissions. However, it is not clear just what
effects on toxic metal emissions can be generally predicted. Toxic metals
such as lead, cadmium, and chromium are found in significant proportions in
the combustible fraction of waste in the form of colorants, paints,
stabilizers, and inks. Therefore, removal of iron, aluminum, and other
non-combustibles from the waste may not eliminate emissions of the heavy
metals from incinerated waste.
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The Swedish Environmental Protection Board has estimated that 5 percent
of Sweden's annual cadmium emissions can be attributed to nickel-cadmium
batteries; therefore, removal of batteries from the waste stream should result
in a decrease in cadmium-containing ash and particulate matter formed in the
combustion process. Even more significant is the Swedish government's
estimate of mercury emissions due to combustion of alkaline pyrolusite
batteries. Alkaline batteries contain about 1 percent mercury by weight. Of
an estimated 5,400 kg of mercury emitted in 1984 in Sweden, approximately
2,200 kg was attributed to combustion of batteries and 1,100 kg to combustion
of other mercury-containing waste. With goals of reducing both cadmium and
mercury levels 1n the Swedish environment, a campaign to separate batteries
from municipal waste has now begun. Environmental hazards posed by batteries
have also been noted at a combustor in Wurzburg, West Germany, where a special
bin was provided for battery disposal. In the case of mercury emissions,
these separation practices may represent the most effective means of reducing
emissions, because test data Indicate only 30 to 40 percent control of mercury
emissions by available control technologies (see "Municipal Waste Combustion
Study: Flue Gas Cleaning Technology.")
Separation of other toxic materials such as paints and pesticides,
possibly could decrease the potential for toxic materials emissions from
combustion. However, the significance of emissions decreases that could be
achieved through such measures Is not presently clear. Such measures could
help diminish, and certainly would not be expected to exacerbate,
environmental effects of combustion.
Hydrochloric add emissions are also of concern in the operation of
municipal waste Incinerators. Paper and plastics have been shown to be major
sources of chlorine In the waste and are, therefore, assumed to be major
contributors to HC1 emissions. With that in mind, one may presume that
removal of significant quantities of paper and plastic from the waste stream
should reduce HC1 emissions significantly. But, there are also significant
quantities of chlorine In other parts of the refuse, such as food, so, it is
not clear what effect removal of large quantities of paper and plastic would
have on HC1 emissions from combustion. No confirming data on reducing HC1
through removal of paper and plastic were found.
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Another issue raised with chlorine in the waste is the question of its
contribution to the formation of chlorinated organics, particularly
chlorinated dibenzo-para-dioxins (CODs) and chlorinated dibenzofurans (CDFs),
in the combustion process. The presence of CDOs and CDFs in emissions from
municipal waste combustion is well documented. However, despite extensive
study, the mechanism (or mechanisms) leading to formation of these compounds
is not well understood. A discussion of potential COO/CDF formation
mechanisms is given in the volume titled "Municipal Waste Combustion Study:
Combustion Control of Organic Emissions."
The potential for PVC-bearing wastes to act as a precursor for CDD/CDF
emissions from municipal waste combustors has been studied by several
researchers. Swedish laboratory experiments demonstrated that CDDs and CDFs
12
are formed from PVC under pyrolytic conditions. Furthermore, in research
sponsored by the Ontario Ministry of the Environment and conducted by
F.W. Karasek at the University of Waterloo in Ontario, Canada-, catalytic -
formation of CDDs and CDFs was observed when the thermolysis products of PVC
o 14
combusted in air were heated to 300 C in the presence of clean flyash. The
results of these experiments have not yet been published, pending attempts to
reproduce these findings.
Despite these findings which tend to link PVC with CDD/CDF formation, it
is unclear how separation and removal of PVC-bearing waste would affect
emissions of CDDs and CDFs from municipal waste combustors. In one recent
study, flyash samples from 6 municipal waste combustors in 4 countries were
collected and analyzed for CDOs and COFs using the same analytical
procedures. The lowest concentrations of CDOs and CDFs were found in a
flyash sample from a Japanese waste combustor where refuse was first sorted to
remove metal and plastic wastes before combustion. The remaining facilities
burned unsorted waste. Although the COD and CDF concentrations were found to
be lower in the Japanese combustor flyash samples, the isomer patterr.^ in all
of the combustor flyash samples were found to be similar, indicating that the
same basic mechanisms and precursors were operating at all facilities.
Swedish researchers also noted a similarity in the pattern of individual COD
and CDF isomers measured in samples of emissions from municipal waste
combustors and from laboratory pyrolysis experiments involving PVC and other
chloroal iphatic compounds, despite the wide variation in chlorine content (1
l ?
to 90 percent).
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Research to date has shown that PVC is capable of producing CDDs and CDFs
under laboratory conditions. However, the mechanism by which this
transformation occurs is not clearly defined. More research is needed to
explain the role of PVC and other potential pathways and reactants that may
contribute to formation of CDO/CDF in municipal waste combustors. Based on
the recent studies cited above, it appears unlikely that 100 percent removal
of PVC and other plastic waste materials from municipal waste before
combustion would eliminate emissions of CDDs and CDFs from municipal waste
combustors. For this reason, the importance of combustion optimization and
effective flue gas controls as a means for reducing CDD/CDF emissions must
continue to be emphasized. These measures are described in more detail in two
other volumes titled, "Municipal Waste Combustion Study: "Combustion Control
of Organic Emissions;" EPA/530-SW-87-021c and "Municipal Waste Combustion
Study: Flue Gas Cleaning Technology," EPA/530-SW-87-021d.
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5.3 REFERENCES
1. Bozeka, Carl G. Nashville Combustor Performance Tests in 1976 National
Waste Processing Conference Proceedings. ASMI.
2. Mazanec, F.J. Compatibility of Recycling with Resource Recovery.
Presented at the Fifth National Recycling Congress, September 24-26,
1986, Seattle, Washington.
3. Sommer, Edward J. and Garry Kenny. Effects of Materials Recovery on
Waste-to-Energy Conversion at the Gallatin, Tennessee Mass Fired Faculty
in ASME Conference. Or! and-..Florida. June 3-6, 1984.
4. Franklin Associates, LTD. Characterization of Municipal Solid Waste in
the United States, 1960 to 2000. EPA Contract No. 68-01-7037, Work
Assignment 349. July 1986.
5. Shapiro, Peter, e_£. aj.. The Integration of Energy and Material Recovery
in the Essex County Solid Waste Management Program. Department of
Planning and Economic Development, Division of Solid Waste Management.
April 1983.
6. Salas, Ada C., David F. Lewis, and Donald A. Oberacker. Waste-To-Energy
Facilities: A Source of Lead Contamination in Municipal Solid Waste:
Resource Recovery, 7th Annual Research Symposium. EPA-600/9-81-002C.
U.S. Environmental Protection Agency, Cincinnati, Ohio. March 1981.
7. Energy From Waste, Chapter 10. The National Energy Authority and The
National Environment Protection Board for the Swedish government.
August, 1986. Translated by Garden Associates, Inc. Edina, MN.
8. "The Report of the National Electrical Manufacturers Association Dry
Battery Section." January 24, 1985.
9. Hinchey, Maurice, Chairman. New York State Legislative Commission on
Solid Waste Management in Norway, Sweden, Denmark, and Germany: Lessons
for New York. December 1985. Albany, N.Y.
10. Churney, K.L., fii aj.. The Chlorine Content of Municipal Solid Waste from
Baltimore County, MD. and Brooklyn, NY. U.S. Department of Commerce,
National Bureau of Standards. Gaithersburg, MD. NBS/R 85-3213.
October 1985.
11. Konheim, Carolyn S. fi£ 4].. Authoritative Answers to Common Questions
on Emissions from Resource Recovery Facilities. Konheim & Ketcham,
Brooklyn, N.Y. October 1986.
12. Rappe, C. and K. Ballschmidter. The Chemistry of Dioxins. Working Paper
prepared for the WHO working group on risks to health of Dioxins from
Combustion of Sewage Sludge and Municipal Waste. Naples, Italy. March
1986.
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13. long, H.Y. and F.W. Karasek. Comparison of PCDD and PCDF in Fly-Ash
Collected from Municipal Incinerators of Different Countries.
Chemosphere. Vol. 15, 1986.
14. Karasek, F.W. and L.C. Dickson. Model Studies of the Formation of PCDOs
during Municipal Waste Incineration. (In press). Science.
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