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4.5.5.4. Commingled Plastics
Commingled plastics recycling, although limited in its end-market application,
offers a relatively simple and flexible reprocessing alternative to sorting and
cleaning mixed plastics. Most programs that collect plastics for recycling
concentrate their efforts on one or two resins, but the opportunity to collect large
quantities of multiresin materials exists. Separating this growing variety of plastics
presents a significant technical challenge.
A number of ventures have successfully applied extruder and compression
mold technology to the reprocessing of unsorted, mixed plastics into dense
products such as lumber, automobile curbstops, and playground equipment.
Generally, higher solid contaminant levels and decreased tensile strengths restrict
this process to the manufacture of thick-walled end products.
Several commingled plastics processing systems currently are used in the
United States. Most facilities use extruder technology that incorporates the same
basic features discussed in the previous section. These systems are capable of
handling a wide range of unsorted and uncleaned or moderately cleaned scrap.
Most systems also use one segregated resin, preferably polyethylene, as a base or
matrix to which the unsorted scrap is added as filler., The resin mixture is
shredded, mixed, and extruded into molds. Because multiple resins, each with
distinct melt temperatures, may be used in commingled processing, process
temperatures must be carefully monitored to prevent overheating and
decomposition of any of the resins.
Additives are often used to improve the quality and expand the range of
products manufactured from commingled plastic wastes. Recent research has
explored the use of wood and glass fibers, calcium carbonate and mica crystals,
and reinforced plastics to strengthen these products (Salas et al., 1990). In
addition, colorants, impact modifiers, flame retardants, UV stabilizers, and
compounding agents may be added to meet the desired end-product specifications.
These additives are similar to those used in the manufacture of products from
virgin feedstock (see Tables 4-9 and 4-10).
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4.5.6. Steel/Tin •
4.5.6.1. Composition of Ferrous Metal Scrap
This section focuses on steel food containers and beverage cans, which
constitute the largest single source of ferrous metal scrap recovered from MSW
when durables (e.g., white goods) are excluded. The grouping of steel containers
in one category incorporates bimetal cans, tin-plated cans, and all-steel cans.
Bimetal cans contain aluminum ends attached to a steelbody that may or may not
be tin-plated.
The tinplating used in steel can construction is composed of 99 percent steel
and 1 percent tin (Carlin, 1989). Steel is an alloy of iron that contains <1 percent
carbon and is produced by oxidizing carbon, silicon, phosphorous, manganese, and
other impurities present in molten iron and steel scrap to specified minimum levels
(U.S. EPA, 1982). Tinplate is produced either by passing steel sheets through a
bath of molten tin or by electroplating in a continuous process (Grayson and
Echroth, 1980). The tin coating on steel cans protects the container's contents by
creating a layer between the steel and the contents, eliminating the possibility of
reactions between the two.
Steel cans include labels, adhesives, associated inks and pigments, and
container residues. In many recycling programs, either consumers or collection
facilities are responsible for removing labels and cleaning containers. However,
contaminants may still remain on recyclables received by reclamation facilities.
Cans may also include surface coatings that contain both organic and inorganic
chemicals.
The quantity of steel can scrap that can be used for iron and steel fabrication
depends on the product to be manufactured; the facility's ability to handle the
scrap; the density, chemical composition, and the tin content of the bales; and the
amount of tin in the facility's other scrap (Copperthite, 1989). The most important
parameter is the quantity of tin in the can scrap. If the steel cans have not been
detinned, the scrap can contribute only 1 to 4 percent of the steel mill's scrap mix.
If the can scrap has been detinned, the quantity of steel cans used may rise to 10
4-71
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to 20 percent, depending on the tin content of the remainder of the mix and the
product that is to be manufactured.
4.5.6.2. Processing Technologies
The industrial processes that steel cans follow during reclamation include iron
and steel manufacturing and detinning. Iron and steel manufacturers and detinning
facilities acquire steel cans from the collection and sorting facilities discussed
earlier. The steel cans that arrive at these facilities may be baled, shredded,
flattened, or unaltered. Because the steps involved in the recycling of steel cans
are distinctly different for each of the two industries, this section discusses the
processes separately.
Iron and Steel Manufacturing. The iron and steel manufacturing industry in
the United States uses two furnace types, the basic oxygen furnace and the
electric arc furnace, to produce iron and steel. The basic oxygen furnace, which is
used to produce about 60 percent of the steel in the United States, uses an
average of 30 percent scrap feedstock, whereas the electric arc furnace, which
produces about 40 percent of the steel, uses virtually 100 percent scrap (Heenan,
1991). The methods used to introduce (charge) ferrous metal scrap to the furnace,
where it mixes with virgin materials, vary slightly for each type of furnace and are
discussed separately. Despite the differences in the furnace charging steps, the
equipment used and raw material charged are comparable.
Basic Oxygen Furnace. A basic oxygen furnace is a large, open-mouthed
vessel lined with a refractory material. The furnace is mounted on trunnions that
allow it to be rotated 360 degrees in either direction. A typical vessel is 12 to 14
feet across and 20 to 30 feet high. The furnace receives a charge composed of
scrap and molten iron. The feedstock is composed primarily of virgin materials (at
least 70 percent molten iron) (U.S. EPA, 1982). Iron is produced in a blast furnace
using iron ore and other materials. Steel scrap is added to the furnace by dumping
4-72
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it from a large "charge box" or container that is loaded in the scrap yard (U.S. EPA,
1980a). Steel is produced in the furnace by introducing a high-speed jet of pure
oxygen, which oxidizes the carbon and the silicon in the molten iron (U.S. EPA,
1980b). Emissions including metallic oxides, particles of slag, carbon monoxide,
and fluoride are typically released from this process.
Electric Arc Furnace. Electric arc furnaces consist of a cylindrical vessel
made of heavy welded plates, a bowl-shaped hearth, and a dome-shaped roof.
Three graphite or carbon electrodes are mounted on a superstructure located above
the furnace and can be lowered and raised through holes in the furnace roof. The
electrodes carry the energy for melting the scrap charge. Bladders located at the
holes in the furnace roof cool the electrodes and also minimize the gap between
the openings in the roof and the electrodes to reduce emissions, noise, heat losses,
and electrode oxidation. When the electrodes are raised, the furnace roof can be
swung aside so that charge materials may be deposited in the furnace. Ferrous
scrap is added to the furnace from a large bucket, where it is typically placed
following removal from railroad cars or other forms of transport. Any required
alloying agents are added to the furnace through the side or slag door. Alloying
agents used in the electric arc furnace include ferromanganese, ferrochrome, high
carbon chrome, nickel, molybdenum oxide, aluminum, and manganese-silicon (U.S.
EPA, 1982).
Detinning. The chemical detinning process, which removes tin from tinplate
scrap and tin-coated food and beverage cans, is the only significant domestic
source of tin metal in the United States (Grayson and Echroth, 1980). This section
describes the following primary steps involved in detinning:
Unloading of tin-plated scrap
Shredders
Air classifiers and magnetic separators
Chemical detinning
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Separation
Tin removal
The chemical detinning and separation steps take place at all detinning facilities,
whereas the other steps are not always performed. Figure 4-9 illustrates the
primary processing steps involved in detinning plated scrap. The more efficient,
continuous process is used at most modern detinning facilities, although older
facilities may use a batch process.
Unloading of Tin-Plated Scrap. Heavy equipment is used to unload tin cans
from incoming vehicles and place them on a conveyor system that feeds the
shredding mill. Equipment most commonly used to load and unload tin cans are
cranes equipped with magnets and grapples. Once placed on the conveyor
system, the tin cans are automatically fed into a shredder.
Shredders. Tin cans must be shredded for two reasons. First, shredding
loosens and separates contaminants such as paper, glue, lacquer, plastic, organics
(e.g., food residues, dirt), and aluminum ends from the bimetal food and beverage
cans so they can be removed during magnetic separation and air classification.
Second, shredding exposes a greater area of the tin cans to chemicals used to
remove tin from the cans. The area exposed may be up to one square acre per ton
of tin cans (personal communication between TRC Environmental Corporation and
Jerry Bailey of Proler International Corporation on July 31, 1991). See Section
4.4.2 for further discussion of shredders.
Air Classifiers and Magnetic Separators. Once shredded, the cans are
carried by a conveyor system to an air classifier, a magnetic separator, or both to
remove contaminants. These contaminants, depending on their density, either fall
or are blown into disposal containers, which are then transported to a landfill.
Industry sources have reported that the combination of shredding, magnetic
4-74
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1 Tinplate Scrap 1
Continuous Processes y . Batch Processes
r
t
Shredder 1
t
1 Basket Loader 1
y V Detinning
Waste ^\
(Landfilled) ^1
Detinning
Rinse .IE 1
Hot -^ 1
Sodium ^^1
Sulfhydrate "^|
I
Magnetic Separator \
and Air Classifier 1
T
t
J"kS 1^, Rinse
,„.,, ,,. 1 ^1 Solution
1 1
1 .
Detinning
Scrap
t
1 Baler or 1
Bundle Press 1
- t
f Scrap §
1 Steel J
\ \
Treatment Tanks I
f
f
"Detinners Mud"
Sludge
1
t
Molten Tin- 1
Stripper 1
t
f
Ingots 1
ks V* VVatl
Storage
FIGURE 4-9
Detinning Process Utilizing Caustic Soda
4-75
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separation, and air classification removes 98 percent of nonmetallic contaminants
and 99 percent of the aluminum (Process Engineering, 1989). See Section 4.4.2
for further discussion of air classifiers and magnetic separators.
Chemical Detinning. After tin cans have passed through the shredder, air
classifier, and magnetic separator, they are considered clean and have enough
surface area exposed to increase the efficiency of the chemical detinning step.
Detinning is accomplished by treating cans with a hot alkaline solution, usualJy
caustic soda, which contains an oxidizing agent to dissolve the tin and precipitate
it as sodium stannate (Grayson and Echroth, 1980). This step also removes any
contaminants remaining on the scrap such as paints and glues. The cans are
placed in the detinning solution by steel baskets lowered into solution tanks (typical
of batch processes) or a tube-like device that works like a screw conveyor
(Watson, 1989).
Separation. Detinned cans are separated from the detinning solution by
rinse trommels (cylindrical rotating screens). The cans are rinsed with hot water
that is recycled into the detinning tanks. The residual tin remaining on the surface
of the detinned scrap is usually <0.06 percent (Watson, 1989). The detinned
scrap is baled and sold to iron and steel manufacturers for use in new products.
Tin Removal. Tin remaining in the detinning solution is removed through an
electroplating process, which uses electricity to turn the sodium stannate back into
tin metal (Watson, 1989). The tin is then melted off the plates and cast into ingots
that are sold. In older detinning plants, process residues, the spent caustic soda,
and "detinner's mud" are recovered and used by other industries, and any rinse
water is treated and reused. In newer facilities, the spent caustic soda is also
reused by the system. The detinner's mud or sludges are usually sold to tin
smelters as low-grade ore (CBNS, 1988).
4-76
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5. SAFETY CONCERNS ASSOCIATED WITH RECYCLING
AND MITIGATION OPTIONS
5.1. INTRODUCTION
This section considers each of the public health, occupational safety, and
environmental hazards that are associated with the recycling practices and
processes summarized in Chapter 4. The hazard-specific discussions address the
following:
• Sources of the hazard
• Nature of the hazard
• Prevention/mitigation options
Narratives for each hazard are supported by tables that provide a comprehensive
list of the process steps or technologies that are potential sources of a particular
hazard and summarize the prevention and mitigation options. In addition, the
tables indicate the relative significance (low, medium, high) of the hazards, based
on a qualitative assessment of the following criteria:
• The frequency or severity of the hazard
• The ability to control the hazard
• The ability to regulate the hazard
• The prevalence of the hazard in related industries
It should be stressed that the ranking is based on a database that is incomplete.
Much information available to characterize recycling hazards is anecdotal in nature.
Measures of hazard magnitude are generally unavailable.
Many prevention and mitigation options discussed in this section reflect the
requirements of Federal, state, and local regulations. Such regulations may affect
facility, process, and equipment design as well as day-to-day work practices and
procedures. Properly implemented, they may reduce direct hazards to workers and
5-1
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facility-related hazards to public health and the environment, which, range from
traffic accidents to facility emissions.
Compliance with certain regulations and implementation of safe work
practices may be reflected in facility operating plans used at MRFs and other
processing facilities. Although operating plans vary from facility to facility, they
may incorporate the following:
Functions of employees
Operation of equipment
Fire contingency
Contaminant isolation and removal
Staffing contingencies
Medical emergencies
Personal protective equipment
Summaries of applicable regulations
5.2. REGULATIONS APPLICABLE TO RECYCLING OPERATIONS
Occupational health and safety and environmental protection are two broad
regulatory categories that apply to the recycling industry to prevent and mitigate
the hazards addressed in this section. Because of the industry's relative infancy,
there are few laws that specifically target recycling. However, there are significant
Federal, state, and local laws that apply to operations commonly used in recycling.
Some of the more important regulations that serve to control or prevent recycling
hazards are outlined below.
5.2.1. Occupational Regulations
The safety of workers employed in the recycling industry falls under the
auspices of the U.S. Occupational Health and Safety Administration (OSHA),
established in 1970. As defined in 29 CFR 1910, OSHA health and safety
standards apply to workers employed by private sector businesses. OSHA
regulations do not cover the occupational safety of public employees, who are
employed by Federal, state, county, municipal, and other government bodies
5-2
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(Council on Environmental Quality, 1987-1988). Many municipalities operate their
own recycling programs rather than contracting the work to the private sector;
therefore, the population of workers not covered by Federal regulations is
potentially large. One survey indicates that municipal employees collect
recyclables in 33 of the 50 largest U.S. cities that have recycling programs (Smith
and Hopkins, 1992). Some states have established their own occupational health
and safety regulations. State legislation may extend health and safety coverage
under these programs to include government workers. Volunteer workers,
however, also a potentially large population, may be beyond the jurisdiction of both
Federal and state occupational health and safety regulations.
OSHA regulations are grouped into specific categories by equipment type,
operation type, or hazardous material (Table 5-1), along with a small number of
industry-specific rules (e.g., pulp, paper, and paperboard mills). Much of the
machinery used in recycling is common equipment that has been adapted from
other industries and is covered under general OSHA regulations. There is no OSHA"
rule that specifically targets the recycling industry or its workers. Some recycling
program managers have expressed concern over the fact that there are no
recycling-specific rules, whereas others feel current general regulations are broad
enough to cover most hazardous activities that would be encountered in the
recycling industry (Combs, 1992).
Additional regulations and guidelines that may have a bearing on worker
health and safety have been issued by the following organizations and
associations:
American National Standards Institute (ANSI)
American Society of Mechanical Engineers (ASME)
American Society of Testing Methods (ASTM)
National Solid Waste Management Association (NSWMA)
National Fire Protection Association (NFPA)
National Institute of Occupational Safety and Health (NIOSH)
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TABLE 5-1
OSHA Health and Safety Standards Applicable
to the Recycling Industry
OSHA standard
Part 1904
Part 1910
Subpart C
Subpart D
Subpart E
Subpart F
Subpart G
Subpart H
Subpart I
Subpart J
Subpart K
Coverage
Record Keeping
Safety and Health Standards
Access to Employee Medical Records
Walking and Working Surfaces
* Floor and wall openings
* Stairs and ladders
* Scaffolds (proposed changes include
falls)
Means of Egress
Manlifts and Platforms
Environmental Control
* Ventilation
* Noise
Hazardous Materials
* Acetylene
* Flammable liquids
* Others
Personal Protective Equipment
* Eye and face protection
* Respiratory protection
* Head protection
* Foot protection
* Electrical protective devices
General Environment
* Signs and tags
* Hazard identifications
Medical and First Aid
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TABLE 5-1 (continued)
OSHA standard
Subpart L
Subpart M
Subpart N
Subpart O
Subpart P
Subpart Q
Subpart R
Subpart S
Subpart Z
Coverage
Fire Protection
* Fire suppression equipment
* Fire protection systems
Compressed Air Systems
Materials Handling and Storage
* General rules
* Servicing vehicles
* Trucks
* Cranes
Machines and Guarding
* General rules
* Power presses
* Mechanical transmission apparatus
Portable Power Equipment
Welding, Cutting, and Brazing
Special Industries
* Pulp, paper, and paperboard
Electrical
* Systems
* Work protectors
* Maintenance
Hazardous Substances
* Airborne contaminants
* Asbestos
* Bloodborne pathogens
* Hazard communication standard
Source: Combs, 1992; 29 CFR 1910.
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5.2.2. Environmental Regulations
Most environmental regulations that apply to recycling facilities are based on
Federal regulations that are administered by state or local agencies or offices.
Local laws and ordinances regarding issuance of permits to facilities may also
apply.
5.3. SHARP OBJECTS
Source Activity: Opportunities to contact sharp objects are greatest at
points where recyclables are manually separated from MSW, sorted by material, or
otherwise handled (e.g., cleaned, crushed, transported, or stored) are shown in
Table 5-2. The extent of handling required of the consumer and the waste worker
varies depending on program-specific collection and sorting methods. Programs
that require consumers to separate, clean, and sort recyclables may present a
higher potential for public contact with sharp objects than those that collect
commingled recyclables and sort them at an MRF.
The degree and type of mechanization employed in collecting and sorting
also affect the potential for workers to contact sharp objects. Glass sorting, a
process that has proven difficult to automate, routinely exposes workers
performing manual sorting to sharp objects. Some forms of mechanization may
increase the occurrence of sharp objects such as broken glass and shredded metal.
During collection, for example, compactor trucks and elevated loading systems that
dump recyclables into bins from above can cause higher percentages of broken
glass (Glenn, 1990; O'Brien, 1991). Shredding and slicing equipment used in
aluminum, rigid plastics, and steel processing produces a sharp-edged flake or chip.
Hazard Type: Sharp objects found among recyclables fall into two primary
categories: process fragments and contaminants. Rigid recyclables (i.e., glass,
plastic, steel) broken or shredded during collection, sorting, or processing
frequently result in sharp-edged fragments. Hypodermic needles and razor blades
are among the sharp contaminants found mixed with recyclables. Injuries that can
result from contact with sharp objects include cuts, lacerations, punctures, and
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TABLE. 5-2
Sharp Objects Hazards
Type of
hazard
Source activity
Prevention/mitigation
Significance of
hazard
Collection
and sorting
Public health
Occupational
Separation in the
home
Drop-off centers
Buy-back centers
Curbside sorting
Dumping
Tipping floor
Bag breakers
Conveyor systems
Sorting stations
Slicers
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
Public education
Personal protective
equipment
Public education
Worker training
System and
equipment design
Personal protective
equipment
Low
Medium
Material
processing
Occupational
AL - Drying and
delacquering
GL - Manual sorting
PA - Manual sorting
S/T - Unloading scrap
S/T - Air classification
S/T - Magnetic
separation
Public education
Worker training
System and
equipment design
Personal protective
equipment
Low
AL - Aluminum processing
GL - Glass processing
PA - Paper processing
S/T - Steel and tin processing
5-7
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abrasions. These injuries are primarily an occupational hazard, especially to
workers handling recyclables during collection or sorting operations, but may also
be a public health hazard.
Any break in the skin caused by sharp objects can become the site of
infection following exposure to bacteria, viruses, fungi, or parasites (Clayton and
Clayton, 1991). Risk of infection, although uncharacterized, may be significant in
cases where container residues exist. In addition, the Center for Plastics Recycling
Research reports that workers regularly find hypodermic needles inside HOPE milk
jugs (personal communication between TRC Environmental Corporation and Wayne
Pearson, executive director of Plastics Recycling Foundation, on February 11,
1992). Although potential for puncture wounds is the greatest hazard associated
with needle exposure, exposure to infectious agents cannot be precluded.
Prevention and Mitigation Options: Contact with sharp objects can be
minimized through the use of personal protective equipment such as gloves, hard
hats, boots, safety glasses, and overclothes. This equipment must be available to
workers and its use required. Automated sorting systems as well as practicable
design controls effectively reduce sharp object hazards, because there is less
human contact with broken materials. Education is the most effective method to
warn consumers about potential sharp object hazards associated with recycling,
because it is not realistic to expect all consumers to use protective equipment in
the home. In addition, educating the public to avoid mixing sharp contaminants
with recyclables can reduce potential worker exposures during collecting and
sorting operations. Process and facility modifications can limit the generation of
sharp recyciables and the degree to which they must be handled. For instance,
recent trials with collection vehicles fitted with internal nets and baffles designed to
catch falling glass during loading have been found to reduce breakage. Within the
MRF, wooden floors, drop chutes at conveyor ends, and rubber bumper guards on
steel sorting tables have reduced glass breakage (Keller, 1992).
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5.4. ERGONOMIC AND LIFTING INJURIES
Source Activity: Table 5-3 summarizes collection and sorting activities that
often require repeated lifting and twisting motions, a common source of ergonomic
injuries. The public may sustain injuries while carrying heavy bins of recyclables to
the curb for collection. Worker injuries that occur during collection result from
lifting and dumping heavy bins, twisting and reaching during curbside sorting, and
repeatedly climbing in and out of vehicles. Manual sorting activities that occur at
an MRF commonly require reaching, lifting, and twisting motions. A 1988 study of
working conditions in Danish MRFs reported that inappropriate and monotonous
working conditions at conveyor belts resulted in ergonomic strain (Malmros and
Petersen, 1988). Falls and other miscellaneous ergonomic injuries may occur
throughout MRFs, drop-off centers, or other material processing facilities. Elevated
platforms, floor-mounted conveyor belts, and sunken bins or dumpsters increase
the opportunity for falls.
Hazard Type: The potential for ergonomic injuries is a significant
occupational concern for numerous recycling activities. Poorly designed work
stations and improper manual materials handling and lifting practices can result in
various injuries or disorders. These problems are not generally associated with a
single accident, but with repeated, low-level insults to a localized body region. The
back and upper extremities are the most commonly affected areas (Levy and
Wegman, 1988). For example, manual lifting and loading of waste materials into
trucks or containers can result in lower back injury and pain. Driving-related
injuries include back injuries as well as vibrational fatigue. Frequent or repetitive
forceful hand motions with awkward posture can affect the musculoskeletal
system or the peripheral nervous system at the fingers, hand, wrist, elbow,
forearm, and shoulder resulting in inflammation of tendons and joints and nerve
compression. The following are examples of repetitive motion disorders (Clayton
and Clayton, 1991; Levy and Wegman, 1988):
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TABLE 5-3
Ergonomic and Lifting Injuries
Type of
hazard
Source activity
Prevention/mitigation
Significance
of hazard
Collection
and sorting
Public health
Occupational
Separation in the home
Drop-off centers
Buy-back centers
Curbside sorting
Loading and dumping
of collection vehicles
Transportation during
curbside collection
Tipping floor
Conveyor systems
Sorting stations
Balers
Drop-off centers
Buy-back centers
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
Public education
Equipment design
Worker training
System and equipment
design
Rotating worker
activities
Personal protective
equipment
Low
Medium
Material
processing
Occupational
GL - Manual sorting
PA - Manual sorting
PL - Manual sorting
S/T - Unloading scrap
Lifting
Equipment operation
Worker training
System and equipment
design
Rotating worker
activities
Personal protective
equipment
Low
GL - Glass processing
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
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Carpal tunnel syndrome (nerve disorder of the wrist)
Degenerative joint disease
DeQuervain's disease (inflammation of the tendons of the thumb)
Trigger finger
Epicondylitis ("tennis elbow")
Rotator cuff tendinitis (shoulder)
Tension neck syndrome
Pain in the upper extremity and neck
Prevention and Mitigation Options: Poorly designed collection vehicles and
other equipment that require workers to make repeated awkward motions during
collection and sorting increase the possibility of ergonomic injuries. In many cases,
these hazards can be successfully eliminated through design improvements. Truck-
mounted automated lift systems, for instance, are now available to hoist and dump
containers of recyclables into collection vehicles. The distance workers must reach
to sort recyclables at the curbside is minimized on newer collection truck bodies
designed with "low-profile" sorting bins. The lower bin position on these models
reduces lifting heights, making sorting safer and more efficient. Taller driver
compartments with lowered floors and full-length doors allow workers to step from
the vehicle to the curb more easily.
Within the MRF, the potential for ergonomic injuries during material sorting
can be minimized substantially through the redesign of equipment and methods.
Stations where workers manually sort recyclables can be engineered to lessen the
range of motion required of the workers. Head-on sorting stations are believed to
minimize the physical strain during sorting, which often results from reaching and
twisting across a conveyor belt. The head-on method balances the workers' range
of motion to both sides, minimizes motion extremes, and eliminates the need to
stretch across the belt. Adjusting the height of conveyor belts or working surfaces
to meet worker dimensions also has been shown to reduce strain at sorting
stations and other operations (Solomon-Mess, 1991). To limit ergonomic stress
during sorting, some recycling firms rotate workers to other activities on a regular
basis (Powell, 1992). Cushioned floors in working areas and elevated foot rests
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effectively reduce the strain on workers' legs. The potential for falls can be
minimized by using guardrails, warning tape, and signs.
As new materials are recycled and members of the public become more
efficient recyclers, larger bins will be required to separate and store recyclables in
the home. Some consumer recycling bins already are designed with wheels to
facilitate moving recyclables from the home to the curb.
5.5. FIRES AND EXPLOSIONS
Source Activity: The sorting and storage of combustible paper products and
the presence of flammable chemical residues pose the primary fire and explosion
hazards associated with recycling (Table 5-4). Large volumes of paper stored in
the home or MRF are a fire hazard whether wet or dry. Dry paper easily can be
ignited in areas where it is stored or processed. Explosions may occur in shredder
chambers, slicers, crushers, and balers when residues of flammable or explosive
substances (e.g., gasoline, propane, cleaning solvents, mineral spirits, batteries) are
ignited (Kohn, 1989; Nollet, 1989a, b; Engineering News Record, 1990).
Explosions are more likely when an unsorted mixture of MSW is shredded. Many
of the heating methods and chemicals used in reprocessing recyclables also can
cause fires or explosions. When aluminum is melted, for example, moisture
trapped in the melt has been known to explode.
Hazard Type: Hazards associated with fire or explosions are primarily
occupational and environmental. Burns are the greatest hazard posed by a fire or
an explosion and can vary in severity from minor superficial burns to deep tissue
damage. Explosions can result in damaging noise exposure (Section 5.8).
Environmental impacts include fire-related air emissions.
Prevention and Mitigation Options: Frequent collection and processing
reduces combustible paper stockpiles in the home and MRF. Because loose paper
is more flammable than baled, baling can minimize the potential for fires. Storing
baled paper in a dry, well-ventilated location reduces the chance of spontaneous
combustion. Shredder explosions can be avoided by visually inspecting and using
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TABLE 5-4
Fire and Explosions
Type of hazard
Source activity
Prevention/mitigation
Significance
of hazard
Collection and
sorting
Public health
Occupational/
Environmental
Storage in the home
Drop-off centers
Curbside handling
Sorting stations
Shredders
Drop-off centers
Front-end separation at
transfer stations,
landfills, waste-to-
energy plants
Proper storage
Public education
Frequency of
collection (paper)
Public education
Frequency of
collection and
processing (paper)
System design (e.g.,
ventilation,
equipment isolation)
Emergency response
equipment/
procedures
Flammables removals
during sorting
Low
Medium/low
Material
processing
Occupational/
Environmental
AL - Smelting
PA - Material storage
PL - Shredding and
grinding
S/T - Shredding
Public education
Frequency of
collection and
processing (paper)
System design (e.g.,
ventilation,
equipment isolation)
Emergency response
equipment and
procedures
Flammables removals
during sorting
Low
AL - Aluminum processing
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
5-13
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magnetic detectors and separators to identify potentially dangerous metal
containers (e.g., propane tanks, aerosol cans) within the recyclable stream so that
they can be removed before shredding. Auxiliary ventilation systems that exhaust
flammable vapors and circulate fresh air through the shredder chamber also can
reduce explosion hazards. Locating shredders in dedicated, sealed rooms designed
to contain an explosion is an additional precaution that isolates the equipment and
protects workers throughout the facility. Adequate fire detectors, sprinkler
systems, and firefighting equipment should be installed in all recycling facilities.
5.6. FLYING AND FALLING DEBRIS
Source Activity: Debris can fly or fall during most stages of processing
(Table 5-5). Flying materials can result at drop-off centers where the public is
often required to sort recyclables by throwing or dropping them into uncovered bins
or dumpsters. Recyclables may fall on workers during operations when the
recyclables are being loaded into collection vehicles, sorted in overhead booths, or
conveyed through an MRF by belts or cranes. Collection vehicles fitted with
automated hoist loaders, for instance, lift bins high over the side of the truck where
recyclables are dumped and possibly fall onto workers below. In many MRFs, it is
customary for workers performing manual sorting to drop or throw sorted
recyclables down chutes into collection bins located below. Fast-moving
equipment commonly used in MRFs and other processing centers (i.e., bag
breakers, metal and plastic shredders, glass crushers and grinders) can throw
recyclables from the equipment at high velocities. For example, it is reported that
glass is frequently projected from the top of crushing or grinding equipment
(personal communication between TRC Environmental Corporation and Steve
Apotheker, journalist, Resource Recycling Magazine, on August 14, 1991). Heavy
bales of recyclables also represent potential falling object hazards when they are
transported or stacked precariously.
Hazard Type: Flying and falling objects may lead to a variety of
occupational injuries to unprotected workers. Items accidentally dropped from
5-14
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TABLE 5-5
Flying and Falling Debris
Type of
hazard
Source activity
Prevention/mitigation
Significance of
hazard
Collection and
sorting
Public health
Occupational
Drop-off centers
Loading and
dumping
collection vehicles
Tipping floor
Sorting stations
Air classifications
Magnetic separators
Glass crushers
Slicers
Shredders
Drop-off centers
Front-end separation
at transfer
stations, landfills,
waste-to-energy
plants
Public education
Equipment design
Worker training
System and
equipment design
(e.g., equipment
isolation,
shielding)
Personal protective
equipment
Low
Medium
Materials
processing
Occupational
AL-Shredding
GL-Crusher and
grinder
PA-Manual sorting
PA-Magnetic
separators
PL-Shredding and
grinding
Worker training
System and
equipment design
(e.g., equipment
isolation,
shielding)
Personal protective
equipment
Medium
5-15
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TABLE 5-5 (continued)
Type of
hazard
Occupational
(continued)
Source activity
S/T - Iron and
steel
manufacture
S/T - Separation
Prevention/mitigation
Significance of
hazard
AL - Aluminum processing
GL - Glass processing
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
5-16
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overhead may cause head, neck, and shoulder injuries, such as fractures,
concussions, and lacerations {Levy and Wegman, 1988). Objects also can be
dropped during material handling (lifting or carrying) and cause injuries to feet and
toes, such as crushing injuries, fractures, and contusions. Flying objects can cause
cuts and lacerations or strike unprotected eyes and result in eye injuries, including
blindness. To a lesser extent, the general public is susceptible to similar hazards as
recyclables are handled at drop-off centers.
Prevention and Mitigation Options: Personal protective equipment such as
hardhats and safety glasses helps prevent injuries from both flying and falling
debris. In addition, establishing and maintaining safety zones beneath elevated
equipment and in dumping areas are an effective means of limiting worker exposure
to falling objects. Objects hurled from processing equipment can be contained by
proper guards and housing on shredders and other equipment. Most new
equipment is sold as completely enclosed units; however, custom-made or adapted
equipment may lack adequate housings. In some cases, additional plastic sheeting
or other guards added to the mouth of a shredder will help to contain flying
objects. Employees should be trained to use equipment only when aii guards are in
place. Physically isolating equipment that can produce flying or falling objects in a
separate room whenever possible will further reduce hazards to workers.
5.7. TEMPERATURE AND PRESSURE EXTREMES
Source Activity: Recycling operations potentially expose workers to
temperature extremes during outdoor collection activities and indoor processing at
facilities with inadequate climate controls (Table 5-6). Indoor temperature
extremes are a particular concern because operations frequently occupy large
buildings, have numerous delivery doors and openings, and are therefore difficult to
heat and cool adequately. Because of prohibitively high costs, it is not uncommon
for small municipalities to operate facilities without a climate control system in
place. A variety of recyclable reprocessing techniques may expose workers to
temperature and pressure extremes. The primary concerns are heated liquids
5-17
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TABLE 5-6
Temperature and Pressure Extremes
Type of
hazard
Source of activity
Prevention/mitigation
Significance
of hazard
Collection
and sorting
Occupational
Tipping floor
Drop-off centers
Collecting and sorting
on route
Worker training
Facility design
(e.g., climate
control systems)
Personal protective
equipment
Low
Material
processing
Occupational
AL - Dying and
delacquering
Al - Smelting
AL - Casting and
cooling
PA - Pulper
PL - Washing
PL - Separation
PL - Extrusion
S/T - Chemical
detinning
Worker training
System and equipment
design (e.g.,
shielding, equipment
isolation)
Process modifications
Personal protective
equipment
Low
AL - Aluminum processing
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
5-18
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generated during container washing, plastic separation, or pulping operations and
hot machine parts such as extruder blades or aluminum and steel furnaces. Plastic
extruders and some paper pulping equipment also operate at high pressures.
Hazard Type: Exposure to high or low ambient temperatures and contact
with hot materials are primarily occupational hazards. Processes that involve
heating of materials or wash water (temperatures can be at least 160°F) can result
in burns. Many facilities have inadequate or no climate control, thus potentially
exposing workers to extreme temperatures. Prolonged exposure to high ambient
temperatures (e.g., in or around furnace or kiln areas or collection activities during
warm times of the year) may result in heat-related illnesses. Susceptibility to heat
stress also is dependent on physical fitness, the level of exertion required, and
clothing. Heat-related illnesses include heat exhaustion, heat cramps, and heat
stroke (Zenz, 1988).
Heat Exhaustion: Heat exhaustion occurs from increased stress on various
body organs. Signs and symptoms include general weakness and dizziness,
excessive perspiration, cool moist skin, and a weak pulse.
Heat Cramps: Heat cramps are caused by heavy sweating with inadequate
water and electrolyte replacement. Heat cramps are characterized by pain in the
hands, feet, and abdomen as well as muscle spasms.
Heat Stroke: Heat stroke, which is the most serious form of heat stress,
occurs when the body's temperature regulation mechanism fails and the body's
temperature rises to critical levels. Symptoms include hot dry skin, severe
headache, nausea, dizziness, and a strong rapid pulse. Left untreated, heat stroke
can lead to coma and death.
Exposure to severe or prolonged cold temperatures (in unheated process
areas) also can result in various adverse health effects. Cold weather injuries
include the following:
Frostnip and Frostbite: Frostnip is characterized by sudden blanching or
whitening of the skin. Superficial frostbite results in firm, waxy, or white skin with
5-19
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the tissue beneath remaining resilient. Deep frostbite results in cold, pale, and
frozen tissue.
Hypothermia: Hypothermia is a fall in the deep core temperature of the
body. Symptoms generally appear in five stages: severe shivering; apathy,
drowsiness, and rapid cooling of the body to less than 95°F; unconsciousness,
glass stare, slow pulse, and slow respiratory rate; freezing of the extremities; and
death, if left untreated.
Prevention and Mitigation Options: Exposures to indoor temperature
extremes can be controlled through the installation of adequate climate control
systems. A popular solution to the challenge of heating or cooling a large, open-air
building is to isolate workers within small enclosed booths. Sorting workers, for
instance, can be housed within a climate-controlled booth within the larger facility.
Collection workers can be encouraged to wear appropriate clothing and provided
with training on the symptoms and prevention of thermal stress. Training, in
addition to guards, shields, and personal protective equipment, also can prevent
exposure to temperature and pressure extremes associated with processing
equipment. Process modifications that minimize the use of temperature extremes
also can be implemented. One plant in Alabama has developed an aluminum
melting process that drastically reduces its use of high temperatures, minimizing
the potential for worker exposures (personal communication between TRC
Environmental Corporation and Mitch Chow of Alabama Reclamation of Sheffield,
AL, on August 7, 1991).
5.8. MOVING EQUIPMENT AND HEAVY MACHINERY
Source Activity: Stationary as well as mobile equipment present hazards to
workers in recycling facilities (Table 5-7). Examples of stationary equipment
include balers, conveyors, crushers, shredders, slicers, overhead cranes, and an
assortment of reprocessing equipment such as plastic extruders, paper pulpers, and
steel furnaces. Moving mechanical parts on this equipment, even under normal
operating conditions, present potential hazards. To meet the unique processing
5-20
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TABLE 5-7
Moving Equipment and Heavy Machinery
Type of
hazard
Source activity
Prevention/mitigation
Significance of
hazard
Collection and
sorting
Public health
Occupational
Drop-off centers
On-route collection
Loading and dumping
collection vehicles
Operation of heavy
equipment
Tipping floor
Bag breakers
Conveyor systems
Sorting stations
Slicers
Shredders
Balers
Drop-off centers
Front-end separation
at transfer
stations, landfills,
waste-to-energy
plants
Personal protective
equipment
Worker training
Public education
Facility design
Worker training
System and
equipment design
(e.g., shielding,
emergency shut-
off, safety zones,
emission controls,
ventilation)
Low
Low
Material
processing
Occupational
AL - Balers and
compactors
AL - Bale breaking
AL - Shredding
AL - Dying and
delacquering
AL - Casting and
cooling
Personal protective
equipment
Worker training
System and
equipment design
(e.g., shielding,
emergency shut-
off, safety zones,
emission controls,
ventilation)
5-21
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TABLE 5-7 (continued)
Type of
hazard
Source activity
Prevention/mitigation
Significance
of hazard
Material
processing
Occupational
(continued)
GL - Manual sorting
GL - Magnetic
separation
GL - Velocity trap
and air classifier
GL - Screening
PL - Material storage
PL - Conveyor
systems
PL - Screening and
cleaning
PL - Separators
PL - Manual sorting
PL - Shredders and
grinders
PL - Washing
PL - Separation
PL - Drying
PL - Aluminum
separation
PL - Extrusion
S/T - Iron and steel
manufacture
S/T - Unloading
scrap
S/T - Shredding
S/T-Air
classification
S/T - Magnetic
separation
Low
AL - Aluminum processing
GL - Glass processing
PL - Plastic processing
S/T - Steel and tin processing
5-22
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and handling demands of recyclables, recycling operations often adapt equipment
from farming or other uses. Safety attachments may be removed or hazardous
equipment configurations created in customizing equipment of processing systems.
Mobile equipment includes vehicles used during collection and transport and
within an MRF or other facility. Dedicated recyclable collection vehicles now
include a variety of hoists and loading mechanisms that increase hazards such as
pinch points and the opportunity for a vehicle to contact overhead trees and
electrical wires. Standard waste collection vehicles pose similar physical hazards.
Within recycling facilities, the close interaction of workers and equipment (e.g.,
forklifts, loaders), particularly on the tipping room floor, poses a considerable
accident hazard. The public also can be put at risk at drop-off centers if access to
areas where machinery is used is not strictly controlled.
Workers may endanger themselves if they do not take proper precautions
when they perform equipment maintenance. Balers, conveyor belts, shredders,
moving parts on collection vehicles, and other types of equipment can become
jammed with recyclables (e.g., plastic or metal containers, broken glass, paper).
Dislodging jams and other on-the-spot repairs may endanger worker safety because
of accidental start-ups if proper electrical lock-out procedures are not followed.
Hazard Type: Moving equipment and heavy machinery pose primarily
occupational safety hazards, although accidents can occur when consumers handle
recyclables at drop-off centers. Injury can be caused by the crushing, squeezing,
or pinching of a body part between a moving object and a stationary object or
between two moving objects (Levy and.Wegman, 1988). Examples of such
injuries include catching fingers and other body parts in conveyor belts (Martin,
1991), workers falling onto conveyors and being killed in a shredding machine (DPI,
1989), and workers contacting moving parts by climbing into trucks or bailer
chamber bins to dislodge jammed material (Keller, 1989).
Another hazard related to recycling equipment includes accidents (tipovers)
and emissions associated with forklift and loader operations (carbon monoxide [CO]
and particulates): A study conducted at the Langard Demonstration Project (a
5-23
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resource recovery facility in Baltimore, Maryland) measured carbon monoxide levels
of 100 ppm to 900 ppm on the facility's tipping floor when more than two trucks
were present (STC, 1979). The OSHA permissible exposure limit for CO is 35
ppm. Early signs of CO poisoning include headache, weakness, lassitude, and
mental confusion. If exposure is prolonged, CO prevents the normal uptake and
distribution of oxygen in the body and may ultimately have lethal effects (Section
5.12 "Gaseous Releases").
Prevention and Mitigation Options: Injuries associated with material
processing and handling equipment can be avoided through the appropriate
placement of guards and shields. Consideration of equipment interfacing is
especially important because unique hazards can exist when equipment of various
makes are integrated.
Injuries during equipment maintenance can be reduced by positioning
multiple emergency power shut-off buttons, cords, and switches along process
lines that include hazardous equipment (e.g., balers, conveyor belts, shredders).
As a result of incidents of crushing injuries associated with balers, easily accessible
safety switches are now being placed within baler chambers (Dessoff, 1991).
Strictly observed electricity lockout practices during the maintenance of automated
equipment limit the possibility of accidental start-ups.
Training regimens stressing safety practices for the use of specialized
equipment help prevent injuries resulting from equipment misuse. Safety zones and
warning signs alerting employees to hazardous areas and equipment also help
prevent accidents.
Proper ventilation and vehicle emission controls can help reduce worker
exposures to vehicle emissions during loading and unloading operations.
5.9. NOISE
Source Activity: A summary of recycling activities that generate significant
levels of noise, including collection, sorting, and general material handling, is
provided in Table 5-8. Aside from the noise associated with equipment motors and
5-24
-------
Significance
of hazard
Prevention/mitigation
Collection and
sorting
Public health
Occupational
Material
processing
Occupational
Consumer drop-off at
collection centers
Curbside collection
Transportation during
processing
Tipping floor
Air classification
Magnetic separators
Aluminum separators
Glass crushers
Slicers
Shredders
Front-end separation at
transfer stations,
landfills, waste-to-energy
plants
Residential drop-off at
collection centers
Curbside collection
Transportation during
processing
AL - Shredding
GL - Manual sorting
GL - Crushers/grinders
PA - Magnetic separators
Vehicle and
equipment design
Collection and
transport scheduling
Vehicle and
equipment design
System design (e.g.,
equipment isolation,
shielding)
Personal protective
equipment
Low
Medium
Vehicle and
equipment design
System design (e.g.,
equipment isolation,
shielding)
Low
5-25
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TABLE 5-8 (continued)
Type of
hazard
Occupational
(continued)
Source activity
PL - Shredders and
grinders
S/T - Shredders
Prevention/mitigation
Personal protective
equipment
Significance
of hazard
AL - Aluminum processing
GL - Glass processing
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
5-26
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engines, significant noise is generated by contact between aluminum, glass, and
steel containers when they are loaded on a collection vehicle, dumped on the
tipping floor, or transported on conveyor belts. Specific processing equipment
such as air classifiers, metal and plastic shredders, and glass crushing and grinding
equipment are also noisy. Noise may result from the use of heavy trucks,
compactors, and automated loaders and compactors during neighborhood
collection.
Hazard Type: Excessive noise is primarily an occupational hazard but also
can be a public health concern associated with certain collection activities. The
effects of noise on the ear are related to the duration of exposure and the intensity
of the noise. Noise can have direct effects on both the middle and inner ear. The
current OSHA standard for continuous noise for 8 hours is 90 dBA, with higher
levels permissible for shorter periods of time. The American Conference of
Governmental Industrial Hygienists (ACGIH) Threshold Limit Value is 85 dBA.
Noise levels above these standards are considered damaging. One study of noise
levels measured throughout the front-end processing stages at a resource recovery
plant revealed levels ranging from 85 to 90 decibels on the tipping floor and at the
shredders. Levels between 90 and 100 decibels were measured at the primary and
secondary shredders and at the magnetic separator (Mansdorf et al., 1981).
The primary health effect associated with noise exposure is noise-induced
hearing loss (NIHL). There are three categories of NIHL (Levy and Wegman, 1988;
Zenz, 1988; Clayton and Clayton, 1991): (1) acoustic trauma, which can be the
effect of a single intense noise followed by ringing in the ear and a shift in the
hearing threshold; there also can be damage to the eardrum if peak exposure levels
exceed 160 dBA; (2) temporary threshold shift (TTS), which is temporary hearing
loss with recovery within a few hours or days following removal from the noise if
the noise has not been too loud or the exposure too long; the cumulative effect of
noise levels of less than 85 dBA also can lead to TTS; and (3) permanent threshold
shift (PTS) can result if the noise is of sufficient intensity and duration to damage
the sensory cells in the inner ear. Diminished ability to understand speech in a
5-27
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setting with noisy background is a pronounced effect of NIHL. Some individuals
also experience ringing ears and headaches in addition to their hearing loss.
Prevention and Mitigation Options: A simple and inexpensive means of
reducing worker noise exposure is to require the use of earplugs or headphone-
style protectors. Another option is the use of engineered controls that reduce the
levels of noise generated. Using soundproof sorting booths as a means of isolating
workers from noisy operations is gaining popularity in MRFs nationwide. Sound-
deadening panels and dividers also can be used effectively to separate areas where
noise is generated, such as the tipping floor, from areas where workers are
stationed. Noisy equipment (e.g., shredders and grinders) can be fitted with
sound-deadening attachments, or it can be isolated in a separate room or
enclosure. Selecting quieter collection vehicles or reducing the number of vehicle
trips to collect all MSW can minimize noise effects on the public.
5.10. AESTHETIC IMPACTS
Source Activity: Collection vehicles and recycling facilities can constitute
aesthetic impacts themselves or generate other impacts including overall
appearance effects, odors, and litter (Table 5-9).
In general, the release of litter is a concern more during recyclable materials
collection than it is during MSW collection (personal communication between TRC
Environmental Corporation and Alan Watts, recycling coordinator for Solid Waste
Services, a division of the Environmental Conservation Services Department,
Austin, TX, in August 1991). Drop-off centers can be a source of litter and often
have an unkempt appearance because they are frequently unmanned. Discarded
items frequently are left on the ground when bins are full or the items are not
recyclable. In addition, people scavenging recyclables for profit can leave a drop-
off center in disarray. Odors may be emitted from unclean recyclables during
storage or reprocessing. For example, plastics that have absorbed butyric acid
have been knpwn to emit an acrid odor on exposure to heat during extrusion
(Hernandez et al., 1988).
5-28
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TABLE 5-9
Aesthetic Impacts
Type of
hazards
Collection and
sorting
Public health
Source activity
Consumer collection
Curbside collection
Drop-off centers
Transportation
during processing
MRFs
Prevention/mitigation
Public education
Facility design (e.g.,
screening
elements, secure
storage areas,
fences)
Significance
of hazard
Low
5-29
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Hazard Type: Aesthetic impacts are primarily a public health concern.
Although aesthetic impacts do not directly impair health, indirectly they affect the
psychologic confidence of individuals. Excessive odors and litter can diminish the
public's support and result in complaints and opposition to MSW programs.
Prevention and Mitigation Options: Visual impacts can be minimized
through the thoughtful use of screening elements (e.g., bushes, fences, walls,
trees, earth berms). New facilities can be designed with greater attention paid to
aesthetic quality. Litter and odors can be controlled by avoiding the use of
uncovered, outdoor material storage areas. Odors can be reduced by effective
washing of recyclables. Perimeter fences also can help to control windborne litter.
Stationing an overseer at drop-off facilities or restricting access to the facility
during nonstaffed hours will limit inappropriate dumping and scavenging. Garbage
containers placed at drop-off facilities will help decrease litter.
5.11. TRAFFIC
Source Activity: Traffic hazards are attributable to trucks collecting
recyclables at the curbside, private vehicles delivering recyclables to drop-off and
buy-back centers, and vehicles (e.g., trucks, trains, barges) transporting
recyclables between processing and within facilities. Traffic hazards are
summarized in Table 5-10. Specifics of program organization and equipment type
dictate the nature of traffic hazards. A drop-off or buy-back operation may have a
higher occurrence of vehicle accidents involving private vehicles, whereas a
curbside program may have a higher rate of accidents involving collection trucks.
Hazard Type: Traffic poses public health, occupational, and environmental
*
hazards. Vehicular accidents (including pedestrian accidents), release of materials
from collection vehicles, emissions (hydrocarbons, NOX, carbon monoxide, and
particulates) and maintenance-generated wastes, and noise are all traffic related
hazards.
Workers collecting recyclables may be subject to traffic-related hazards
during collection and truck-loading activities. Two-sided sorting may result in a
5-30
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TABLE 5-10
Traffic Hazards
Type of
hazard
Source activity
Prevention/mitigation
Significance
of hazard
Collection and
sorting
Public health
Occupational
Environmental
Drop-off centers
Buy-back centers
Consumer drop-off at
collection centers
Curbside collection
Transportation during
processing
Drop-off centers
Buy-back centers
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
Curbside collection
Transportation during
processing
Drop-off centers
Buy-back centers
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
Curbside collection
Transportation during
processing
Vehicle maintenance
Public education
Vehicle design (e.g.,
emission controls,
safety features)
System design (e.g.,
traffic flow)
Collection and
transport
scheduling
Worker training
Vehicle design (e.g.,
emission controls,
safety features)
System design (e.g.,
traffic flow)
Collection and
transport
scheduling
Personal protective
equipment
Vehicle design (e.g,
emission controls)
Proper waste
handling
Vehicle equipment
Low
Low
Low
5-31
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higher accident rate because it has the potential to place workers in the path of
traffic (personal communication between TRC Environmental Corporation and
Pamela Harris, director of Loss Control Services for Browning Ferris International
[BFI], Houston, TX, on September 13, 1991).
Although it is difficult to draw conclusions from the limited existing data on
traffic accidents associated with recycling operations, statistics from a program in
Austin, Texas, suggest that recycling vehicles can be more prone to accidents than
other MSW collection vehicles. Statistics from 1986 and 1987 reveal that
recycling vehicles accounted for approximately 30 percent of accidents involving
collection vehicles and approximately 20 percent of the total vehicles in the
collection fleet (personal communication between TRC Environmental Corporation
and Sergio Martinez, safety specialist for Solid Waste Services, a Division of the
Environmental Conservation Services Department, Austin, TX, in August 1991).
Specific vehicle design and route organization features (e.g., truck size, loading
design, number of workers assigned to each collection crew) are possible factors
contributing to these higher rates.
Prevention and Mitigation Options: A thorough, safety-conscious traffic-
flow plan can minimize potential accident hazards at all types of recycling facilities.
Traffic safety zones can be established within which no vehicles are allowed. A
well-organized collection strategy that anticipates and avoids periods and routes of
high traffic will help reduce road accidents. Conducting safe-driver training,
recognizing good drivers, and installing safety signs, mirrors, and other equipment
can reduce traffic hazards at facilities and on the road.
Emerging collection strategies such as those that utilize efficient, lightweight
collection vehicles that unload to larger vehicles for distance driving have the
potential to reduce energy use and emissions. The type of truck chassis and
engine used and the amount of stop-and-go driving required during collection
influence fuel efficiency and related vehicle emissions. Keeping vehicles well
maintained reduces emissions.
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5.12. PROCESS CHEMICALS AND CONTAINER RESIDUES
Source Activity: A summary of process chemicals and residues of
hazardous chemicals in recyclable containers that pose direct hazards at a number
of processing points (Sections 5.13 through 5.18 for indirect hazards associated
with these chemicals and other residues and contaminants) is provided in Table
5-11. Examples of common process chemicals include chlorine and other paper
bleaching and pulping agents, aluminum fluxing agents and compounds, plastics
additives, and equipment cleaning solvents. In some cases (e.g., paper deinking
and pulping), chemicals are used in open vats or other containers from which
splashing may endanger workers.
Container residues may include insecticides, herbicides, and other lawn and
garden products; paints, stains, and construction products; automotive oils and
cleaners; gasoline, kerosene, and other fuels; and miscellaneous household
cleaning products. Individuals may be exposed to these residues during collection,
cleaning (rinsing), and storage of recyclables in their homes. Workers are exposed
to residues primarily during collection, sorting, and washing steps. For example,
elevated pesticide levels also have been reported in wash water resulting from
pesticide-saturated paper labels (personal communication between TRC
Environmental Corporation and George Pisacano of the Center for Plastics Recovery
Research, Rutgers University, on February 12, 1992). Certain container and label
materials may be more likely than others to absorb and retain chemical residues.
Hazard Type: Mishandled or mismanaged process chemicals or residues can
cause adverse effects to workers and the public. Direct skin contact, inhalation,
and incidental ingestion exposures are possible. The health hazards associated
with the chemicals and residues that may be encountered are summarized below.
Process Chemicals: Chlorine and fluorine, process chemicals used to
remove magnesium from aluminum cans, are strong eye and respiratory irritants
(Sittig, 1991). Fluoride compounds also are associated with central nervous
system and skin disorders. Certain chemicals used in the deinking process could
result in adverse health effects if proper controls are not in place. Repeated
5-33
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TABLE 5-11
Process Chemicals and Container Residues
(Direct Impacts)
Type of
hazards
Source activity
Prevention/mitigation
Significance
of hazard
Collection and
sorting
Public health
Occupational
Consumer collection
Curbside sorting
Dumping
Bag breakers
Sorting stations
Drop-off centers
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
Public education
Public education
Worker training
Personal protective
equipment
System and
equipment design
(e.g., storage
practices,
ventilation)
Low
Medium
Material
Processing
Occupational
AL - Smelting
PA - Pulper
PA - Screening and
cleaning
PA - Clarifier
PA - Bleaching
PA - Effluent treatment
PA - Sludge disposal
PL - Manual sorting
PL - Washing
PL - Separation
PL - Extrusion
S/T - Chemical
detinning
Public education
Worker training
Personal protective
equipment
System and
equipment design
(e.g., storage
practices,
ventilation)
Medium
AL - Aluminum processing
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
5-34
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exposure to corrosive alkaline solutions such as sodium hydroxide can cause ,
dermatitis.
Chemicals used during plastics processing are not generally hazardous.
Difficulty in handling and disposing of hazardous solvents is one reason why more
benign detergents usually are used in washing steps. Plastic resins and container
labels can absorb organic residues such as pesticides. Health effects associated
with exposure to pesticides include primarily skin and central nervous system
disorders. Long-term exposures to certain pesticides can cause liver and kidney
damage. Some pesticides are carcinogens.
Container Residues: Potential effects associated with container residues
vary widely according to the type of residue. Possible effects range from short-
term irritant effects to long-term toxicity and cancer. Hazardous constituents
banned or reduced in concentration in current products may be present in old
containers collected for recycling. Potential health and safety issues associated
with residues are addressed under the regulatory authority of the Food and Drug
and Cosmetic Act. Fire and explosion hazards associated with chemical residues
are discussed in Section 5.5.
Prevention and Mitigation Options: Personal protective equipment including
glasses, gloves, and aprons is recommended for reducing chemical exposures.
Requiring workers to shed dedicated work uniforms before leaving the facility also
will help reduce exposures to chemical spills (Solomon-Hess, 1991). In addition,
showers and eyewash stations can help to minimize contamination. Adequate
enclosures on processing vats, secure storage practices, and enhanced ventilation
systems also prevent worker exposures to process chemicals. To minimize a
release in the event of a chemical spill, some recycling facilities have installed
separate run-off collection systems that are designed to collect and treat water
contaminated with oil and other waste substances (Combs, 1991). Both
occupational and public health exposures can be prevented by educating the public
to avoid recycling containers with exceptionally hazardous contents and to properly
wash or decontaminate containers before disposal.
5-35
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5.13. GASEOUS RELEASES
Source Activity: Gases released are summarized in Table 5-12. Aside from
occasional gaseous releases attributable to container residues (Section 5.12.),
releases from recycling operations often are associated with heating or melting
process stages or gases or volatile chemicals used to clean or refine recycled
materials (Sections 5.8. and 5.11. contain information on emissions from
equipment and vehicles). Potential release may vary with the material processed.
Emissions from aluminum delacquering processes that burn paint and coatings may
include organic contaminants and heavy metals such as lead and cadmium. Steel
melting and demagging operations typically release metallic oxides and chlorides as
well as acid and chlorine gases. Heavy metals contained in label inks also may be
released. Bleaching agents (e.g., chloroform and chlorine) are released from
processing and wastewater treatment operations associated with wastepaper
recycling.
Plastics processing involving heating, particularly drying and extrusion
molding operations, has the potential to release gaseous degradation products such
as acids, volatile organic compounds (VOCs), carbon dioxide, and carbon monoxide
(Allen, 1983). When most resins are melted, there is the possibility of releasing
small quantities of unreacted monomer as well as any additives, dyes, and
compounding agents. HOPE extruder operations have been found to release 0.63
kg of VOCs per mg of resin processed (Radian Corporation, 1985). One study has
confirmed that some degradation of HOPE resin can occur during heating (Gibbs,
1990). Melting polystyrene above 280 degrees also has been shown to produce
styrene monomer emissions (Brighton et al., 1979). Plastic degradation from
overheating, scorching, and burning usually occurs by accident and is usually
caused by equipment malfunctions, operator error, or improper equipment
maintenance. Commingled plastics processing also raises the likelihood of
exceeding resin degradation temperatures because it can involve simultaneously
heating resins with different melt temperatures.
5-36
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TABLE 5- 12
Gaseous Releases
Type of hazard
Collection and
sorting
Public health/
environmental
Occupational
Material
processing
Public health/
occupational/
environmental
Sources
MRFs
Front-end separation at
transfer stations,
landfills, waste-to-
energy plants
Consumer drop-off at
collection centers
Curbside collection
Transportation during
processing
Shredders
Front-end separation
Transfer stations.
landfills, waste-to-
energy plants
Consumer drop-off at
collection centers
Curbside collection
Transportation during
processing
AL - Drying and
delacquering
AL - Smelting
PA - Screening and
cleaning
PA - Bleaching
PA - Milling
PL - Extrusion
Prevention/mitigation
System and
equipment design
(e.g., emission
controls, chemical
reuse)
System and
equipment design
(e.g., emission
controls,
ventilation.
chemical reuse)
Personal protective
equipment
System and
equipment design
(e.g., emission
controls.
ventilation.
chemical reuse)
Personal protective
equipment
Significance
of hazard
Low
Low
Low
5-37
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TABLE 5-1 2 (continued)
Type of
hazard
Sources
S/T - Iron and
steel
manufacturing
S/T - Shredding
Prevention/mitigation
Significance of
hazard
AL - Aluminum processing
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
5-38
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Hazard Type: Gaseous releases associated with various recycling
operations may result in potential exposure of workers, the public, and
environmental receptors to a variety of toxic substances if proper controls are not
employed. The magnitude of releases from recycling facilities that can affect the
public and the environment is difficult to characterize.
In a remanufacturing facility, organic and metal oxide contaminant releases
are possible during the delacquering and smelting of aluminum to remove impurities
such as paints, coatings, and container residues. Exposure to metal oxides,
including zinc, copper, magnesium, aluminum, antimony, cadmium, copper, iron,
manganese, nickel, selenium, silver, and tin, may result in a flu-like condition
known as metal fume fever. The symptoms of metal fume fever include chills,
increased sweating, nausea, weakness, headache, muscle pain, and cough. The
fever often begins with thirst and a metallic taste in the mouth (Levy and Wegman,
1988). In general, acute effects of solvent exposure include irritation of the
respiratory tract, skin irritation, and central nervous system effects. Long-term
health effects associated with organic compound exposure include liver, kidney,
and gastrointestinal disorders. Certain solvents that may be used in or generated
during certain recycling processes are classified by EPA as potentially carcinogenic
to humans. In the paper deinking process, use of chlorine-based bleaches has been
associated with the releases of dioxins and chloroform, both of which are
potentially carcinogenic to humans. Exposure to dioxins also is associated with
disorders such as chloracne, nervous system disorders, and liver damage (Sittig,
1991).
Many of the emissions from thermal decomposition of plastic resins are
similar to those associated with the processing of virgin feedstock and include
various classes of organic compounds. Possible acute health effects associated
with worker exposure to organic compounds include irritation of mucous
membranes and the respiratory system, dermatitis, and central nervous system
effects (U.S. Department of Health and Human Services, 1990). Long-term
exposures may cause liver, kidney, and gastrointestinal damage.
5-39
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Prevention and Mitigation Options: Public exposure can be minimized
through emission control technologies that are available to reduce gaseous releases
from recycling facilities. Depending on their size and complexity, systems can
reduce worker exposures by venting gases outdoors or eliminating harmful
emissions altogether. Cost is the primary factor that limits the application of state-
of-the-art air filtration systems, particularly at small, start-up operations with limited
capital reserves. Fixed carbon-bed absorbers, electrostatic precipitators, distilling
equipment, and fractionalizers all can be used effectively to reduce air emissions.
For example, the acidic degradation byproducts of PVC processing can be
neutralized using a sodium hydroxide mist (personal communication between TRC
Environmental Corporation and Brian Doty, plant manager, Innovative Plastic
Products, Inc., Greensboro, GA, on July 29, 1991). Wet scrubbers can be used to
control gaseous emissions from drying and delacquering operations. In the
absence of emission control systems, personal protective equipment such as
respirators will reduce worker exposures.
5.14. PARTICULATE RELEASES
Source Activity: Virtually every operation within an MRF or processing
facility generates some airborne particulates. A summary of particulate releases is
provided in Table 5-13. Sorting activities, trommel screens, air classifiers, glass
crushers, shredders, and other equipment that moves or manipulates recyclables
are potential dust sources. Shredding and blowing equipment tends to generate
the most particulates. Studies conducted at the Langard resource recovery facility
in Baltimore, Maryland, identified high dust levels in the material receiving area
(STC, 1979).
Certain materials produce more particulates, or particulates that are more
hazardous, when they are shredded or processed. Paper, because of its fibrous
nature, generates significant dust when it is sorted or shredded. Other dusts
include fine glass shards from crushing or grinding, plastic fines from shredding,
and aluminum and steel bits from shredding and demagging and detinning. The
5-40
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TABLE 5-13
Particulate Releases
Type of hazard
Source activity
Prevention/mitigation
Significance
of hazard
Collection and
sorting
Public health/
environmental
Occupational
Drop-off centers
MRFs
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
Curbside collection
Transportation during
processing
Most other processing
facilities
Tipping floor
Trommel screens
Air classifiers
Shredders
Drop-off centers
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
Curbside collection
Transportation during
processing
System and
equipment design
(e.g., emission
controls)
System and
equipment design
(e.g., emission
controls, ventilation)
Personal protective
equipment
Low
Medium
5-41
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TABLE 5-13 (continued)
Type of hazard
Source activity
Prevention/mitigation
Significance
of hazard
Material
processing
Public health/
occupational/
environmental
AL - Drying and
delacquering
AL - Smelting
GL - Crusher and grinder
GL - Screening
GL - Aluminum
separation
PA - Trommel screens
PL - Shredding
S/T - Iron and steel
manufacture
S/T - Shredding
S/T - Separation
System/equipment
design (e.g., emission
controls, ventilation)
Personal protective
equipment
Low
AL - Aluminum processing
GL - Glass processing
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
5-42
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processing technique, material processed,,and the ventilation conditions all affect
the amount of airborne particulate material. Although some recycling facilities
report dust to be a significant problem, an inspection conducted by the Vermont
Health Department in a facility that regularly grinds PVC scrap found nuisance dust
to be below allowable levels (personal communication between TRC Environmental
Corporation and Fred Satink of the Vermont Department of Health on July 29,
1991).
Hazard Type: Particulate releases from recycling activities may pose
potential public health, occupational, and environmental hazards. Uncontrolled
dust may be inhaled or swallowed with food or saliva. In general, the principal
potential health effects of particulate exposure include the aggravation of asthma
or other respiratory or cardiorespiratory symptoms, increased cough and chest
discomfort, and increased mortality. In addition, the toxic action of some gases
may be enhanced when they are adsorbed to respirable particles. The health
effects associated with inhalation of particles is dependent on the location and
extent of their deposition in the respiratory system. Several factors influence
particle deposition, retention, and clearance, including the anatomy of the
respiratory tract, particle size, and breathing patterns. Children are considered to
be more susceptible to particulate pollution. Environmental effects of particulate
emissions include soiling and deterioration of building materials and other surfaces,
cloud formation, and interference with plant photosynthesis (Clayton and Clayton,
1991). Dust levels measured in studies at resource recovery plants have ranged
from 118 to 202 mg/m3 in the vicinity of a shredder to as low as 38 mg/m3 (Diaz
et al., 1981). The OSHA Permissible Exposure Limit (PEL) for inert or nuisance
dusts is 15 mg/m3 for total particulates and 5 mg/m3 for the respirable fraction.
Some dusts generated during certain recycling activities contain metal fines.
Acute exposure to metal dusts can cause irritation of the upper respiratory system
and eventually severe pulmonary irritation (Levy and Wegman, 1988). Heavy
metals reported in air emissions from MRFs include cadmium, chromium, nickel,
lead, and mercury (Visalli, 1989). Cadmium, chromium (hexavalent), lead, and
5-43
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nickel are carcinogenic to animals and humans when inhaled. Chronic exposure to
mercury and lead can result in adverse effects to the central nervous and
gastrointestinal systems; lead is also a probable carcinogen.
Exposure to fine glass particles can result in the development of silicosis
because silica is a primary component of glass. Particles less than one micron in
diameter present the greatest danger because they can penetrate to respiratory
bronchioles and alveoli (Last and Wallace, 1992; Zenz, 1988). Such particle sizes
are typically associated with grinding or sandblasting glass. Crushing of glass
during recycling activities is not likely to produce particles that small.
Prevention and Mitigation Options: Ventilation and filtration systems and
personal protective equipment are two approaches to controlling dust and
protecting workers from elevated levels of airborne particulates. Filtration systems
collect contaminated air and feed it to a bag house or an air scrubber system that
removes contaminants. The latter method has proved effective for removing glass
and other particulates from ambient air (U.S. EPA, 1977). Building-wide, negative
air flow systems also have been used to draw air to a central filtration unit, but
these systems are difficult to implement in large facilities like MRFs with many
openings. An alternative is dust collection hoods on specific pieces of equipment
that generate dust (e.g., shredders, air classifiers, plastics grinders). Operating
equipment such as shredders at slower speeds has been found to further reduce
dust generation rates (Toensmeir, 1987). The use of isolated booths to house
sorting workers in a climate-controlled environment also is gaining acceptance as a
method for limiting exposures to airborne contaminants. Dust masks and
respirators can reduce the hazard to workers; however, the equipment must be
properly selected, consistently used, and replaced when necessary. Workers often
do not use masks because they are uncomfortable and considered a nuisance.
5.15. WATERBORNE RELEASES
Source Activity: Wastewater is generated by recycling operations ranging
from washing containers in the home to industrial paper pulping and plastic
5-44
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washing systems (Table 5-14). The public generally washes food and paper
particles down the drain. MRFs and other facilities that receive recyclables and
commingled wastes can generate effluents containing a variety of liquids from
container residues to rain water. Run-off from the tipping floor and other
processing areas within a recycling facility often is discharged to the storm or
sanitary sewer.
Water-based cleaning and sorting processes have the potential to generate
large volumes of waste water. For example, water is used extensively at several
stages of wastepaper pulping and cleaning. Effluents containing chlorine and its
byproducts, inks, and dyes are generated by screening, bleaching, washing, and
filtering operations. The levels of chemical and physical contaminants vary
depending on the type of paper being processed and the degree of wastewater
treatment that takes place before release. Several types of plastics shredding or
grinding, cleaning, and separation equipment also use water to wash and transport
plastic flakes. A B.F. Goodrich vinyl recycling operation in Akron, Ohio, adds a
1-percent solution of dishwasher detergent to hot-water wash solutions (Summers
et al., 1990).
Another source of facility effluents is water-based air filtration systems (e.g.,
wet scrubbers) used to control air emissions. Air filtration skimming and scrubbing
processes are frequently used at aluminum and steel facilities. Contact cooling
waters also can include a number of contaminants.
Hazard Type: Process wastewater and effluents from emission control
systems result in primarily environmental hazards. Wastewater from aluminum
processing may contain metals, phenolics, oil and grease, and suspended solids.
Wastewater from paper processing may include chlorine-derived dioxins, PCBs, and
heavy metals and solvents from inks. Although toxic constituents in manufactured
goods are increasingly regulated, recycling of older products can contribute to the
release of these contaminants. These substances exhibit both carcinogenic and
noncarcinogenic health effects in humans. The primary environmental concerns are
BOD loading of receiving waters and toxic effects on aquatic organisms.
5-45
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TABLE 5-14
Waterborne Releases
Type of
hazard
Source activity
Prevention/mitigation
Significance
of hazard
Collection and
sorting
Public health/
environmental
Separation in the home
Tipping floor
System and
equipment design
(e.g., collection,
treatment, reuse)
Low
Material
processing
Public health/
environmental
AL - Scraping, drying,
and delacquering
AL - Smelting
AL - Casting and
cooling
PA - Separators
PA - Clarifiers
PA - Bleaching
PA - Dewatering and
thickening
PA - Milling
PA - Separation
PA - Washing
PL - Separation
PL - Washing
S/T- Iron and steel
manufacture
System and
equipment design
(e.g.,collection,
treatment, reuse)
Low
AL - Aluminum processing
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
5-46
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Prevention and Mitigation Options: Dedicated systems can be installed to
collect and treat facility effluents before release. Standard treatment techniques
include primary and secondary clarifiers, neutralization, activated sludge, aerated
stabilization, and anaerobic processes. Certain anaerobic processes can reduce
BOD by as much as 95 percent (Amoth et al., 1991). The use of alternative
chemicals such as nonchlorine bleaches and other nonhazardous process chemicals
has reduced the quantity of dioxins released by secondary paper plants. Most
wastewaters from cleaning, sorting, reprocessing, or air filtration also can be
recycled to minimize effluent discharges. For instance, paper recycling plant
effluents have been successfully filtered and recycled (Horacek, 1983).
5.16. SOLID WASTE AND SLUDGE
Source Activity: Residual material is generated as a result of sorting and
refining operations that purify waste materials for remanufacture (Table 5-15). An
assortment of gross solid discards and sludge byproducts generated as recyclables
is initially processed at the MRF. More rigorous sorting, filtering, and refining that
occur during subsequent processing generate a variety of sludges and finer
contaminants. These discards are generally landfilled, incinerated, landfarmed, or
discharged with wastewater.
A survey of 41 operating and proposed MRFs found residue generation rates
ranging from less than 1. to 25 percent of the material entering a facility. Most of
the discards frpm the MRFs generating more than 10 percent waste were found to
be mixed-color cullet (Glenn, 1989). The remainder of the residue is difficult to
categorize and is not generally salvageable.
Aluminum reprocessing generates both solid and sludge discards. Fabric
filters used to collect aluminum fines, slag and dross collected during skimming,
and demagging residues captured by emission control equipment are examples of
aluminum reprocessing wastes.
Paper recycling generates large quantities of sludge and a variety of solid
discards including plastic, bindings, cellophane, rubber bands, staples, and paper
5-47
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TABLE 5-15
Solid Waste and Sludge
Type of
hazard
Collection and
sorting
Public health/
environmental
Material
processing
Public health/
environmental
Source activity
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
MRFs
PA - Manual sorting
PA - Magnetic
separators
PA - Trommel
screens
PA - Pulper
PA - Screening and
cleaning
PA - Separators
PA - Clarifier
PL - Washing
PL - Separation
PL - Extrusion
S/T - Air classifiers
S/T - Magnetic
separation
S/T - Tin removal
Prevention/mitigation
Process and system
design (e.g., careful
sorting, reuse of
waste, glass
breakage reduction)
Treatment and
disposal facility
design
Process and system
design (e.g., careful
sorting, reuse of
waste, glass
breakage reduction)
Treatment and
disposal facility
design
Significance
of hazard
Low
Low
PA - Paper processing
PL - Plastic processing
S/T - Steel and tin processing
5-48
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clips (Sixour, 1991). It is estimated that deinking and pulping operations will
produce as much as 700,000 tons of sludge in 1995 (Usherson, 1992). This is
caused primarily by fiber losses and high clay and ink content of certain waste
paper grades. Heavy metals, PCBs, and dioxins are contaminants of concern in
paper processing sludges.
Plastics cleaning, sorting, and filtration often generate soil, rocks, off-
specification plastics, metals, labels, detergent, and solvents. Filtrate quantities
vary widely depending on the type and quality of the plastic being processed. A
filtration system that uses a coarse wire screen on an extruder for processing PET
bottles may collect 4 to 5 chips of aluminum (averaging 3 mm2 in size) per 10 kg
of PET processed (Wissler, 1990). One plastics recycling facility reported
landfilling more than 16,000 pounds of wet filtrate (as much as 50 percent water)
for every 5 to 10 cubic feet of plastics processed (personal communication
between TRC Environmental Corporation and Garry Thompson. M. A. Industries,
Inc. Peachtree City, GA, in July 1991).
Hazard Type: Many of the process chemicals and contaminants found in
effluent streams also can occur in sludge. Trace quantities of heavy metals, PCBs,
dioxins, and other chlorinated organic compounds are found in recycling plant
sludge. Metals measured in deinking sludges are listed in Table 5-16. As
mentioned previously, exposure to these contaminants can result in both
carcinogenic and noncarcinogenic toxic effects. Extent of exposure and the
bioavailability of chemicals in the waste and sludge will affect the potential for
adverse effects. Public health and environmental hazards can result from releases
during solid waste and sludge treatment and disposal.
Prevention and Mitigation Options: Solid waste and sludge residues from
recycling processes usually are landfilled or incinerated. Because there are no
completely satisfactory methods to dispose of these wastes, limiting the quantity
that must be discarded is the most effective alternative. Some communities have
begun to write contract clauses requiring waste haulers to limit the percentage of
5-49
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TABLE 5-1 6
Heavy Metal Concentrations in Deinking Sludges (ppm)
Municipal
heavy metal
Cadmium
Chromium
Copper
Lead
Manganese
Nickel
Zinc
Lowest
concentration
0
16.0
31.0
3.0
31.0
1.0
36.0
Highest
concentration
<0.02
118
400
210
880
25
1,000
Source: Hoekstra, 1991.
5-50
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residue per volume of recyclables processed. Such agreements encourage
contractors to perform more careful sorting, which results in fewer residuals.
To reduce glass residue discards, MRFs are being designed to include fewer
handling steps for glass containers. At a large facility in Las Vegas, Nevada, glass
that has been sorted at the curbside is dumped from the truck directly into sorting
bins, which are delivered to the processor. This system not only limits the mixing
of glass types at the MRF, it also requires that each container be handled only once
when it is collected at the curbside (Combs, 1991).
Another modification that reduces the amount of broken glass is the
installation of wooden floors in glass-handling areas (Salimando, 1989). Recently
developed equipment (glass beneficiation systems) has been aimed at purifying
glass residues to create a higher percentage of reusable product.
In some cases, wastes are reclaimed because of the value of certain
constituents. For example, detinning sludges are often reused for their high alkali
content (Grayson and Echroth, 1980). Reuse of other wastes such as paper mill
sludges, which may contain heavy metals, can be more difficult. Paper mill sludges
traditionally have been landfilled or incinerated; however, 58 percent of sludges
were landfarmed in 1990 (Diehn, 1991). Recently, landfarming has become a
popular sludge disposal method, but concerns about heavy metal concentrations
remain. Developing alternative uses for typical waste materials (e.g., the use of
mixed cullet in glasphalt).can reduce the quantity of residue that must be disposed
of.
5.17. MICROBIOLOGIC HAZARDS
Source Activity: Microorganisms such as bacteria, fungi, and viruses often
grow within recyclable containers or on paper products. A summary of source
activities is listed in Table 5-17. Newspapers used in animal litter boxes provide a
growth medium for microbes. Infectious agents also can be present on hypodermic
needles that contaminate the recyclable waste stream. Microbiologic agents are of
particular concern when recyclables are mixed with MSW before sorting, but
5-51
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TABLE 5-17
Microbiologic Hazards
Type of
hazard
Source activity
Prevention/mitigation
Significance
of hazard
Collection
and sorting
Public health
Occupational
Separation in the home
Drop-off centers
Buy-back centers
Curbside sorting
MRFs
Drop-off centers
Buy-back centers
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
Public education
Frequency of
collection and
processing
Public education
Frequency of
collection and
processing
Personal protective
equipment
Vehicle and
equipment
cleaning
Worker training
(cleanliness)
Low
Medium
5-52
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separated recyclables also provide suitable substrate for microorganisms. The
public can be exposed to these hazards when dirty recyclables are stored in the
home for extended periods of time. Operations that increase the risk of worker
exposure to microbiologic hazards include commingled MSW and recyclable
collection, the use of the same vehicles to collect both MSW and recyclables, bag
breakers and other equipment that stir up contaminated materials and potentially
disperse microorganisms, and manual sorting operations that require workers to
handle recyclables and remove putrescible wastes. Facilities that wash plastic
materials, however, report no significant bacterial problems (personal
communication between TRC Environmental Corporation and Garry Thompson, M.
A. Industries, Inc., Peachtree City, GA, in July 1991).
Hazard Type: Although the public may be exposed to microorganisms on
recyclables, exposure potential appears to be greatest among workers. Individuals
may be exposed to microorganisms in aerosols, on dust particles, or on objects
they contact. Pathogenic microorganisms of concern include coliform bacteria
species such as Escherichia co/i and fungi such as Aspergillis (Pahren, 1987). The
most common health problems associated with these pathogens include respiratory
infections, diarrhea, and skin diseases. Contact dermatitis can occur from contact
with fungi.
Worker illnesses have been reported at indoor waste processing facilities
where microbial densities tend to be higher. A 1987 study evaluated dust and
biologic airborne contaminants at Danish waste processing plants and measured
"demonstrated endotoxins {poisonous substances produced by bacteria) in excess
of recommended normal values for air content" (Malmros and Petersen, 1988).
Half the staff members at these facilities were found to suffer from some type of
respiratory system ailment. Additional symptoms included flu-like symptoms,
fever, and eye and skin irritation.
Prevention and Mitigation Options: Teaching the public to wash containers
before recycling will reduce microbial growth. Washing vehicles and other
processing equipment regularly also minimizes the build-up of microorganisms.
5-53
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Frequent collection minimizes public exposure in the home. Personal protective
equipment such as water-resistant gloves have been shown to effectively protect
workers (personal communication between TRC Environmental Corporation and
Pamela Harris, director of Loss Control Services for Browning Ferris International,
Houston, TX, on September 13, 1991). Respiratory protection reduces
occupational inhalation exposures to airborne pathogens.
5.18. PESTS
Source Activity: Pests such as insects and rodents may be attracted to
containers and other recyclables as a food source or nesting medium. A summary
of the source activities is provided in Table 5-18. Pests are a concern when
recyclables are stockpiled in the home or at a recycling facility before collection or
processing. Recyclables contaminated with food residues are particularly
susceptible to pest infestation. Home refuse containers with accumulated residues
have been shown to produce more than 1,000 fly larvae per week (Chanlett,
1979).
Hazard Type: Insects and rodents represent both an occupational and
public health hazard. Flies are contaminated with hundreds of species of
pathogenic microorganisms that can be transmitted to humans (Last and Wallace,
1992). Some culex mosquitoes are wastewater breeders and will breed in dirty
water pools, including rainwater accumulated in stored cans and bottles and other
discarded items (Chanlett, 1979). Rats harbor the pathogens for leptospiras, rat-
bite fever, and salmonellosis (Chanlett, 1979).
Insect bites usually present nuisance conditions such as localized swelling,
itching, and minor pain. However, a hazard and common cause of fatalities from
insect bites—particularly bees and wasps—is a sensitivity reaction. Anaphylactic
shock from stings can include severe reactions by the circulatory, respiratory, and
central nervous systems, which may lead to death.
Prevention and Mitigation Options: Educating the public to avoid mixing
garbage and recyclables and to thoroughly clean containers before storage or
5-54
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TABLE 5-18
Hazards From Pests
Type of
hazard
Source activity
Prevention/mitigation
Significance
of hazard
Collection and
sorting
Public health
Occupational
Separation in the home
Drop-off centers
Curbside sorting
MRFs
Drop-off centers
Buy-back centers
Front-end separation
at transfer stations,
landfills, waste-to-
energy plants
Public education
Frequency of
collection and
processing
Public education
Frequency of
collection and
processing
Personal protective
equipment
Vehicle and
equipment
cleaning
Low
Low
5-55
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collection reduces pest hazards. Frequent and regular collection and processing
reduces excessive recyclable stockpiling, limiting pest habitats and food sources.
Pesticides also can be us.ed to eliminate rodent and insect pests, although their use
is discouraged because of their deleterious environmental effects.
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6. SUMMARY AND CONCLUSIONS
This report presents an overview of the practices and processes used to
recycle municipal solid waste and the associated public health, occupational safety,
and environmental concerns. Aluminum, glass, paper, plastics, and steel and tin
recyclables are tracked through collecting, sorting, and processing. Many safety
concerns identified are generic to the overall handling of MSW, regardless of
whether the materials are recycled or whether the recycling program includes
simple community drop-off centers or automated systems with state-of-the-art
collection vehicles and sorting facilities. Other recycling hazards are specific to the
material or product type being recycled.
Solid waste managements methods, including recycling, pose physical,
chemical, and biologic hazards to workers, the public, and the environment.
Workers typically encounter physical hazards when they handle recyclables during
the collection and sorting stages and also during material-specific processing.
Contact with sharp objects, moving parts, or flying or falling debris can cause
physical injury. Ergonomic injuries can result from poorly designed collection
vehicles or the repetitive motions required of workers at sorting stations within
MRFs. Traffic noise is a safety concern when recycling programs increase the
number of vehicle trips. Noise levels within some MRFs also are known to exceed
OSHA standards. Fires and explosions, although infrequent, are physical hazards
in addition to affecting property.
Chemical hazards can result from airborne (gaseous and particulate),
waterborne, and sludge and solid releases at recycling facilities. Postconsumer
recyclables can contain chemical residues or contaminants. The chemical
composition of the recyclable itself, the coatings and paints applied to products
and packaging, or other additives and process chemicals can contribute to chemical
releases during processing.
Microbes and pests present biologic hazards. Microbiologic agents can enter
MSW directly as a result of consumers discarding contaminated materials such as
6-1
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newspapers from pet litter boxes. Container residues and recyclables composed of
materials that provide suitable substrate present indirect means for the introduction
of opportunistic microorganisms. Rodents and insects are common pests
encountered at facilities handling MSW, regardless of whether the facilities are for
recycling.
Preventive and mitigative options exist to control most hazards encountered
in the recycling industry. Many specific hazards and their sources (equipment or
activities) are not unique to recycling and exist in other industries or in the
collection and disposal of MSW by other options. Although existing standards of
practice do not specifically target the recycling industry, Federal (OSHA, EPA),
state, and other standards apply to many practices and processes used in recycling
and serve to reduce or prevent hazards.
Pollution control technologies exist for most processing operations, but the
extent to which controls are used is difficult to quantify. There are documented
cases in which failure or lack of control equipment has resulted in unacceptable
worker exposures (e.g., noise, fugitive dust). In addition, it is difficult to control
occupational hazards occurring at the initial material-handling stages because some
manual sorting of recyclables is inevitable. Advanced sorting technologies have
the potential to limit worker exposure to recyclable materials and their byproducts,
but as yet the technologies are not widely applied.
Safety procedures, emission control devices, wastewater treatment systems,
and responsible solid waste management practices reduce many of the public
health, occupational, and environmental hazards. In addition, public and worker
education is essential to implementing a safe and successful program.
The significance of hazards identified in this report is summarized in Tables
6-1, 6-2, and 6-3. Each table presents ratings for hazards that occur during
collection and sorting and material-specific processing. The overall processing of
recyclables appears to contribute to increased occupational hazards because of
excessive worker contact through handling and separation of recyclables. The
types of occupational hazards appear to be reasonably similar between material
6-2
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TABLE 6-1
Summary of Public Health Concerns
Public health concerns
Sharp objects
Ergonomic and lifting injuries
Fires and explosions
Flying and falling debris
Moving heavy machinery
Noise
Aesthetic impacts
Traffic
Process chemicals and container residues
Gaseous releases
Particulate releases
Waterborne releases
Solid waste and sludge
Microbiologic
Pests
Activities
Collection and
sorting
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Low
Material-specific
processing
NMS
NMS
NMS
NMS
NMS
NMS
NMS
NMS
NMS
Low
Low
Low
Low
Low
Low
NMS = The hazard identified is not specific to any particular material.
6-3
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TABLE 6-2
Summary of Occupational Safety Concerns
Safety concerns
Sharp objects
Ergonomic and lifting injuries
Fires and explosions
Flying and falling debris
Temperature and pressure extremes
Moving equipment and heavy machinery
Noise
Traffic
Process chemicals and container residues
Gaseous releases
Particulate releases
Microbiologic
Pests
Activities
Collection and
sorting
Medium
Medium
Medium
Medium
Low
Low
Medium
Low
Medium
Low
Medium
Low
Low
Material-specific
processing
Low
Low
Low
Medium
Low
Low
Low
NMS
Medium
Low
Low
NMS
NMS
NMS = The hazard identified is not specific to any particular material.
6-4
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TABLE 6-3
Summary of Environmental Safety Concerns
Environmental concerns
Fires and explosions
Traffic
Gaseous releases
Particulate releases
Waterborne releases
Solid waste and sludge
Activities
Collection and
sorting
Low
Low
Low
Low
Low
Low
Material-specific
processing
Low
NMS
Low
Low
Low
Low
NMS = The hazard identified is not specific to any particular material.
6-5
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types. Available data suggest that the number of hazards potentially affecting
public health and the environment is smaller than that potentially affecting workers.
The separation and sorting of recyclables in the home is a popular collection
strategy. However, programs that require the public to handle and store
recyclables, especially containers and their contents, increase public health
hazards. Moreover, the additional preparation of recyclables that is required to
meet market specifications generates solid discards and cleaning byproducts (e.g.,
material rejects, detergents, effluents).
Generally, recycling increases the number of vehicle trips necessary to
collect MSW. Training and new truck designs can be used effectively to reduce
certain hazards and to increase efficiency.
Lack of data to characterize recycling hazards results from the newness of
recycling programs and certain processes, the proprietary nature of technologies,
and chemical formulations. Occupational health studies and databases on
workplace hazards will permit the significance of occupation hazards to be
assessed. More data to characterize and quantify emissions and effluents leaving
recycling facilities are required to estimate the magnitude of many public health and
environmental hazards.
6-6
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7. ADDITIONAL RESEARCH NEEDS
Insufficient data exist to fully characterize the nature and significance of
MSW recycling hazards. The lack of data is caused in part by recent increases in
recycling activities and innovations in recycling technologies and the corresponding
lag in time required to conduct studies and collect information. The following
research activities would assist in filling key data gaps.
• Characterize the air quality within recycling facilities (e.g., MRFs) and
emissions from these facilities.
• Study pollution and safety control devices and systems to determine the
frequency with which they are being implemented and their applicability,
effectiveness, and cost to the industry.
• Study the ergonomic effects of various practices and processes in
recycling programs. For example, evaluate curbside collection versus
drop-off centers or manual versus automated sorting stations within
MRFs.
• Characterize and quantify wastewater discharges from various types of
recycling facilities to ambient waters.
• Evaluate the impacts of waste-handling facility capacity on the
magnitude of facility-related activities.
• Conduct an epi.demiologic study of workers with acute and chronic
exposures attributable to recycling activities.
• Monitor changes in health biomarkers and the associated health status of
workers.
• Identify sources of microbial hazards associated with recycling facilities,
especially mixed waste processing facilities.
• Conduct a quantitative risk assessment for workers with microbial
exposures.
• Identify inhalation and dermal risks attributable to infectious agents in
MSW.
7-1
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Develop databases of occupational injuries and chemical exposures in
recycling.
7-2
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8-4
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Smith, S.; Hopkins, K. (1992) Curbside recycling in the top 50 cities. Resource
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Appendix B. COMMON RECYCLABLES: AMOUNTS AND MARKETS
ALCOA. (1991) Recycling: it's nature's way. Knoxville, TN.
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Amoth, A.; Lee, J., Jr.; Seamons, R. (1991) Anaerobic treatment of secondary
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Resource Recycling. June.
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U.S. EPA. (1989) The solid waste dilemma: an agenda for action. Office of Solid
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U.S. EPA. (1990) Characterization of municipal solid waste in the United States:
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042A.
Appendix C. FEDERAL, STATE, AND MUNICIPAL INVOLVEMENT
Apotheker, S. (1992) State and provincial recycling organizations get busy.
Resource Recycling. May 1992.
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U.S. EPA. (1989) The solid waste dilemma: an agenda for action. Office of Solid
Waste and Emergency Response. EPA/530-SW-89-019.
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APPENDIX A
GLOSSARY
Recycling is a rapidly evolving industry in which numerous technical terms
are used, many with several meanings or interpretations. The following list of
definitions is provided to assist the reader of this report.
Additive - A substance added to another material (e.g., plastic) in relatively small
amounts to impart or improve desirable properties or suppress undesirable
properties.
Alloy - A mixture or solid solution of two or more metals.
Baler - A machine used to compress recyclables into bundles to reduce volume.
Bottle bill - A law requiring deposits on beverage containers.
Buy-back facilities - A facility where consumers bring recyclables for payment.
Charge - The quantity of a material to be used or consumed that is loaded at one
time into an apparatus (e.g., furnace).
Commingled - Two or more recyclable materials or objects mixed together.
Gullet - Broken glass used to manufacture new glass.
Curbside collection - A MSW management program option in which materials are
collected at the curb and brought to processing facilities,
Drop-off facilities - A collection or processing facility to which consumers bring
recyclables.
Dross - The solid layer that forms on the surface of a molten or melting metal
largely as a result of oxidization or the rising of contaminants and impurities to the
surface.
Ferrous - Types of metal containing iron.
Flux - A substance used to promote fusion of metals by removing impurities or
contaminants.
A-1
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Hazard - A source or condition that can create or increase the potential for danger.
Incinerator - A facility in which combustion of solid waste takes place.
Landfill - An engineered structure designed to isolate waste from man and minimize
environmental risk.
Municipal solid waste - A mixture of household, commercial, and institutional solid
waste.
Nonferrous - Types of metal containing no iron (e.g., aluminum).
Plastic - Any complex synthetic or natural organic compound formed by
polymerization.
Polymer - Any of numerous natural or synthetic compounds consisting of linked
molecules. The words plastic and polymer are used interchangeably.
Recover - The process to regain useable material from waste.
Recyclable - A component of municipal solid waste that can be collected and
reused or processed for use in new products.
Recycling - The process during which an item is subjected to physical or chemical
alterations between the time it is separated from waste and processed into its final
form.
Resin - A class of solid or semisolid organic substances derived from plants or
synthetic materials.
Resource recovery facility or waste-to-energy plant - A facility that accepts and
combusts municipal solid waste as a means of generating energy.
Reuse - An activity in which a material is subjected to small or no alterations in its
physical form and is employed in the same function for which it was originally
designed or built.
Risk - The quantitative estimate of injury, disease, or death under specific
circumstances.
Scrap - Fragments or small pieces of recyclables (generally refers to metals).
Separation - Segregation of recyclables from municipal solid waste.
A-2
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Slag - A substance that floats on molten metal during refining, protects the metal
from oxidation, and removes contaminants.
Smelting - Purifying or separating alloys or ores by melting.
Sort - To manually or automatically select specific recyclable materials and place
them into homogeneous material streams.
Trommel screen - A large, rotating cylindrical screen that is used in MRFs and
paper sorting facilities to remove small and heavy contaminants (e.g., sand, rocks,
paper clips) from a material stream.
A-3
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APPENDIX B
COMMON RECYCLABLES: AMOUNTS AND MARKETS
INTRODUCTION
Aluminum, glass, paper, plastics, and steel and tin represent a large
percentage of the MSW generated in the United States. In 1988, these recyclables
accounted for approximately 63 percent (113 million tons) of the MSW generated
(Table B-1). A report by Franklin Associates (1990) states that in 1988, 19.5
percent (22.3 million tons) of recyclables generated, 12.4 percent of total MSW,
was recovered. Table B-1 lists the material-specific recovery rates. The remainder
was landfilled or incinerated. Recyclables that were disposed of in landfills
accounted for 68 percent of landfill volume. The 1988 recycling rate (12.4
percent) was nearly twice the 1960 rate of 7 percent. It is estimated that recovery
rates will approach 30 percent by the year 2000 (Franklin Associates, 1990).
Given recovery rate increases, markets must expand to absorb recovered materials.
To date, however, market growth for recyclables has not kept pace with recycling
rates. As states continue to pass legislation mandating recycling (see Appendix C),
the supply of recyclables will continue to increase. Although some market
development has occurred, recyclable markets are weak for some materials. This
creates supply excesses that lower the market prices paid for recyclables, making
their collection less desirable.
ALUMINUM AMOUNTS AND MARKETS
Amounts
Aluminum has many commercial applications, including beverage and other
containers, foil, closures, siding, window frames, roofing, mobile home awnings
and canopies, heating and ventilation applications, curtain walls, copper and
aluminum radiators, and appliances. In 1988, more than 4.3 million tons of
aluminum was produced, and an additional 2.4 million tons of scrap aluminum was
reused.
B-1
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TABLE B-1
Materials Recovery From Municipal Solid Waste, 1988
Paper and paperboard
Glass
Weight
generated
(in millions
of tons)
71.8
12.5
Weight
recovered
(in millions
of tons)
18.4
1.5
Percent
recovered
of each
material
25.6
12.0
Discards
(in millions
of tons)
53.4
11.0
Metals
Ferrous
Aluminum
Other nonferrous
Total metals
Rubber and leather
Textiles
Wood
Other
Total nonfood product
wastes
11.6
2.5
1.1
15.3
4.6
3.9
6.5
3.1
132.1
0.7
0.8
0.7
2.2
0.1
0.0
0.0
0.7
23.1
5.8
31.7
65.1
14.6
2.3
0.6
0.0
21.7
17.5
10.9
1.7
0.4
13.0
4.5
3.9
6.5
3.1
109.6
Other wastes
Food wastes
Yard wastes
Miscellaneous
Inorganic wastes
Total other wastes
Total MSW
13.2
31.6
2.7
47.5
179.5
0.0
0.5
0.0
0.5
23.4
0.0
1.6
0.0
1.1
13.1
13.2
31.6
2.7
47.5
157.1
Source: U.S. EPA, 1990.
B-2
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Aluminum recycling is widespread because of several factors. Deposit laws
and dealers who purchase aluminum scrap provide an incentive for the public to
recycle. Aluminum manufacturers prefer recycled aluminum because less than 5
percent of the energy required to make aluminum from bauxite (the principal
aluminum ore) is used to recycle aluminum (Copperthite, 1989; ISRI, 1990a,b;
ALCOA, 1991).
Although aluminum has many applications, the only items recycled in
significant quantities from municipal solid waste are used beverage cans (UBC) and
foil and closures (Franklin Associates, 1990). UBC comprises more than 90
percent of all aluminum recovered from municipal solid waste. Table B-2 shows
that in 1988, 55 percent of beverage cans and 5 percent of foil and closures were
recovered from MSW.
Markets
The recycling of UBC is a closed loop because its predominant market is new
aluminum beverage containers. Although aluminum is not plagued by the chronic
oversupply problems of other recyclables, recent increases in supply have
exceeded the capacity of remelting mills (Misner, 1991). UBC prices are more
dependent on the worldwide price of virgin aluminum ingot than their own supply
and demand because ingot prices reflect the supply and demand atmosphere for
aluminum-can sheet that is produced from UBC (Misner, 1991).
GLASS AMOUNTS AND MARKETS
Amounts
Postconsumer glass can be classified irito functional groups depending on
the method used to form it. Three groups, container glass (bottles and jars), flat
glass (window glass, plate glass, float glass, tempered glass, and'laminated glass),
and pressed and blown glass (ornamental glass and stemware), constitute virtually
all glass produced (U.S. EPA, 1979). As of 1988, 6.9 percent (12.5 million tons)
B-3
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TABLE B-2
Generation and Recycling of Aluminum Products in MSW, 1988
Product category
Major appliances
Furniture and
furnishings
Miscellaneous
durables
Miscellaneous
nondurables
Beverage cans
Other cans
Foil and closures
Total
Weight
generated (in
thousand of
tons)
107
89
280
240
1,439
67
324
2,546
Weight
recovered (in
thousand of
tons)
0
0
0
0
791
0
16
807
Percent
recovered
0
0
0
0
55
0
5
32
Discards
(in thousands
of tons)
107
89
280
240
648
67
308
1,739
Source: Franklin Associates, Ltd., 1990.
B-4
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of all MSW generated in the United States consisted of glass products, 92 percent
of which was container glass (Table B-3).
Nearly 100 percent of the glass recycled from MSW was container glass.
Plate glass does not provide a consistent market for recyclers, and little is recycled
because of the intended durability of the product. Pressed and blown glass also
generally is formed into items considered to be "durable goods."
The most common types of glass are soda-lime, borosilicate, lead silicate,
and opal. Approximately 77 percent of all glass manufactured is soda-lime glass,
which is used exclusively in the production of food and beverage containers
because of the ease and efficiency with which it is produced. Three colors of
soda-lime glass, clear (flint), green, and amber, are commonly produced and
recycled. Green and amber glass are produced by adding minerals such as
^chromium trioxide, iron oxide, and cupric oxide for green glass and sodium sulfide
for amber glass to a flint batch (Grayson and Echroth, 1980). Recyclers generally
segregate by color because clear glass can be used in any batch, whereas colored
glass generally is used to produce recycled products in a specific color.
Markets
The major market for recycled glass (cullet) is glass container manufacturers,
which receive approximately 70 percent of the cullet processed in the United
States. They maintain strict specifications regarding the cullet color and the
amount of contaminants present. In general, only a small amount of green or
amber glass can be added to a batch of flint glass. In the same regard,
manufacturers regulate the amount of off-specification glass in green and amber
batches.
Although glass container manufacturers have promoted their products as
100 percent recyclable, the current supply created by proliferating collection
programs is far exceeding domestic furnace capacity. In addition, relatively high
transportation costs associated with cullet, given its high weight-to-volume ratio,
may make export of the material unprofitable. Green glass imported from Canada
B-5
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TABLE B-3
Generation and Recycling of Glass in MSW, 1 988
Product
category
Durable
goods8
Weight
generated (in
millions of
tons)
1.2
Weight
recovered (in
millions of
tons)
Negligible
Percent
recovered
Negligible
Discards (in
millions of
tons)
1.2
Containers and packaging
Beer and soft
drink bottles
Wine and
liquor bottles
Food and
other bottles
and jars
Total glass
containers
Total glass
5.4
2.0
3.9
11.3
12.5
1.1
0.1
0.3
1.5
1.5
20.0
5.0
7.7
13.3
12.0
4.3
1.9
3.6
9.8
11.0
aGlass as a component of appliances, furniture, consumer electronics, etc.
Source: Franklin Associates Ltd., 1990.
B-6
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is not taken back by the only manufacturer in that country, Consumers Glass,
because it feels the supply of green bottles to Canadian bottlers by U.S.
manufacturers creates a balanced net flow of green glass across the border
(Apotheker, 1991; personal communication between TRC Environmental
Corporation and Steve Apotheker, journalist, Resource Recycling Magazine, on
August 14, 1991).
Fiberglass insulation and sandblasting material represent new markets for
green and mixed cullet. Although the fiberglass industry produces 1.4 million tons
of insulation per year, the market dislocation for green and mixed-color cullet
probably meets or exceeds that entire quantity (Apotheker, 1991; personal
communication between TRC Environmental Corporation and Steve Apotheker,
journalist, Resource Recycling Magazine, on August 14, 1991). One industry
representative estimates that the sandblasting market could absorb about 200,000
tons of cullet annually, although only about 10,000 tons are absorbed currently
(personal communication between TRC Environmental Corporation and Roger
Hecht, vice president, Bassichi's Company, on July 31, 1991).
PAPER AMOUNTS AND MARKETS
Amounts
Wastepaper grades have been defined by the U.S. Bureau of Census into five
major grades: old newspaper (ONP), mixed paper (MP), old corrugated containers
(OCC), high-grade deinking (HGD), and pulp-substitutes (PS) (Amoth et al., 1991).
PS are basically in-plant scrap and require little or no preparation aside from
repulping before being used as a fiber source. ONP, MP, OCC, and HGD may
require cleaning and deinking, but they are still valuable sources of secondary
fibers.
The major source categories of paper in MSW include corrugated boxes,
newspapers, office paper, and books and magazines. Of the 71.8 million tons of
paper waste generated in 1988, these items accounted for 49 million tons. These
items also accounted for the bulk of the paper that was recycled. Table B-4 lists
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TABLE B-4
Generation and Recycling of Paper and Paperboard in MSW, 1988
Weight
generated
(in millions
of tons)
Weight
recovered
(in millions
of tons)
Percent
recycled
Discards
(in millions
of tons)
Nondurable goods
Newspaper
Books and magazines
Office papers
Commercial printing
Tissue paper and towels
Paper plates and cups
Other nonpackaging
paper8
Total paper and
paperboard nondurable
goods
13.3
5.3
7.3
4.1
3.0
0.7
5.2
38.9
4.4
0.7
1.6
0.6
Negligible
Negligible
Negligible
7.4
33.3
13.2
22.5
14.6
Negligible
Negligible
Negligible
18.9
8.9
4.6
5.7
3.5
Negligible
Negligible
Negligible
31.5
Containers and packaging
Corrugated boxes
Milk cartons
Folding cartons
Other paperboard
packaging
Bags and sacks
Wrapping papers
23.1
0.5
4.4
0.3
2.9
0.1
10.5
Negligible
0.3
Negligible
0.2
Negligible
45.4
Negligible
7.7
Negligible
7.0
Negligible
12.6
Negligible
4.1
Negligible
2.7
Negligible
B-8
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TABLE B-4 (continued)
Other paper packaging
Total paper and
paperboard containers
and packaging
Total paper and
paperboard
Weight
generated
(in millions
of tons)
1.5
32.9
71.8
Weight
recovered
(in millions
of tons)
Negligible
11.0
18.4
Percent
recycled
Negligible
33.5
25.6
Discard (in
millions of
tons)
Negligible
21.9
53.4
Includes tissue in disposable diapers, paper in games and novelties, posters, tags,
cards, etc.
X"
Source: Franklin Associates, Ltd., 1990.
B-9
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the various constituents of waste paper in 1988 and the extent to which they were
recycled.
Markets
Historically, the use of recycled fibers, or secondary fibers, in the production
of new paper and paper products has been common practice. The contribution of
secondary fibers to paper production has increased steadily to constitute
approximately 25 percent of new paper production in 1988 (Franklin Associates,
1990).
Repulping or grinding paper into reusable fibers uses well-established
technologies. Removing the ink from newsprint and other inked papers, commonly
called deinking, is one of the primary technical challenges presented by paper
recycling.
A growing number of municipal recycling programs have boosted the amount
of newsprint collected and increased the demand for deinking capacity. Federal
and state legislation suggesting or mandating the use of secondary fibers in new
products has begun to play a role in the rise in secondary fiber utilization. It is
estimated that the use of deinked fibers will grow to 5.8 million tons in the next 10
years. Most of this will be used in newspaper production. If collection rates
continue to grow and deinking capacity expands as expected, it is estimated that
wastepaper utilization rates will rise to nearly 30 percent by 1995 (Franklin
Associates, 1990). Alternative developing markets for waste paper include the
following:
Animal bedding
Egg and fruit boxes from old cartons
Egg and fruit cartons for wastepaper pulp
Building material
Asphalted roofing sheets
Insulating material
Fuel
B-10
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Export is one outlet for the domestic oversupply of recycled paper. In fact, many
dealers or processors export nearly all their waste paper (Misner, 1991). For
example, various grades of paper from the United States are imported by countries
in Asia, where lower labor costs allow more economical paper processing. The
export of waste paper is dependent on the availability of shipping containers
(Misner, 1991).
PLASTIC AMOUNTS AND MARKETS
Amounts
Plastics are broadly classified by their polymer structure as either
thermoplastic or thermoset resins. Thermoplastics are commonly recycled because
they can be melted and reformed, whereas the cross-linked polymers of thermoset
resins cannot.
In the late 1980s, the Society of the Plastics Industry (SPI) voluntarily
devised and implemented a system of seven codes (Figure B-1) to facilitate the
identification and separation of common thermoplastic resins used in packaging
applications (SPI, 1988). The symbols usually appear on the bottoms of containers
and other disposable plastic items. Most postconsumer recycling programs focus
their efforts on reclaiming categories one through six.
Table B-5 lists the various plastic goods recycled in 1988 and their
contributions to recycling of plastics in general. At present, containers made from
polyethylene terephthalate (PET) and high-density polyethylene (HOPE) are the
postconsumer plastics recycled in significant quantities. Both resins are recycled at
higher rates because of their frequent use in packaging. PET is used to
manufacture carbonated beverage containers, 21 percent of which were recycled in
1988. The high recycling rate is attributable to high collection levels in states with
bottle-bill legislation. HOPE is used in base cups for PET bottles and milk and
bottled water containers. HOPE is easily recyclable and is considered a resin of
choice for numerous applications.
B-11
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x \
PET
HOPE
\ \
LPDE
PP
PS
OTHER
1. Polyethylene terephthalate
2. High-density polyethylene
3. Vinyl
4. Low-density polyethylene
5. Polypropylene
6. Polystryene
7. Other, including multilayer
FIGURE B-1
Society of the Plastics Industry Coding System for Plastic Resins
B-1 2
-------
TABLE B-5
Generation and Recycling of Plastics in MSW, 1988
Product category
Durable goods3
Weight
generated
(in millions
of tons)
4.1
Weight
recovered
(in millions
of tons)
<0.1
Percent
recycled
1.5
Discards
{in millions
of tons)
4.1
Nondurable goods
Plastic plates and cups
Clothing and footwear
Disposable diapers'5
Other Misc. nondurables
Total plastics nondurable
goods
0.4
0.2
0.3
3.8
4.7
0
0
0
0
0
0
0
0
4.7
Containers and packaging
Soft drink bottles
Milk bottles
Other containers
Bags and sacks
Wraps
Other plastic packaging
Total plastics containers
and packaging
Total plastics
0.4
0.4
1.7
0.8
1.1
1.2
5.6
14.4
0.1
Negligible
Negligible
Negligible
Negligible
Negligible
0.1
0.2
25.0
<1.0
Negligible
Negligible
Negligible
Negligible
1.7
1.3
0.3
0.4
1.7
0.8
1.1
1.2
5.5
14.3
aAppliances, toys, furniture, etc.
bDoes not include nonplastic materials in diapers.
Source: Franklin Associates, Ltd., 1990.
B-13
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Limitations of collection and sorting systems and other factors have hindered
reclamation of the other coded resins, which include low-density polyethylene
(LDPE), vinyl (V), polypropylene (PP), polystyrene (PS), and others. These resins
appear in a range of products from building materials and luggage to egg cartons
and garbage bags. In 1990, these resins together represented more than 34 billion
pounds of potentially recyclable plastics, 8.9 billion pounds of which were used in
packaging (Modern Plastics, 1991).
Markets
In a study of recycled plastics markets (Bennett, 1989), the Center for
Plastics Recycling Research (CPRR) indicated that current PET markets include the
following:
• Civil engineering-geotextiles and urethane foam
• Recreational-skis, surfboards, and sailboat hulls
• Industrial-carpeting, fence posts, fiberfill, fuel pellets, industrial paints,
strapping, unsaturated polyester, and paint brushes
Based on the CPRR report, current HOPE markets exist in the following areas:
• Agriculture—drain pipes and pig and calf pens
• Marine engineering-boat piers (lumber)
• Civil engineering-building products, curb stops, pipe, signs, and traffic-
barrier cones
• Recreational-toys and golf bag liners
• Gardening—flower pots, garden furniture, and lumber
• Industrial-drums and pails, kitchen drainboards, matting, milk-bottle
carriers, pallets, soft-drink base cups, and trash cans
B-14
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In addition to evaluating the markets for PET and HOPE, CPRR evaluated the
potential markets for mixed plastics, that is, recycled plastic consisting of several
resin types. Six potentially significant markets were identified:
Treated lumber
Landscape timbers
Horse fencing
Farm pens for poultry, pigs, and calves
Roadside pots
Pallets
Although the diversity of potential plastics markets appears great, the development
of these markets is not occurring fast enough, creating an oversupply of recycled
plastics. Industry representatives indicate that curbside collection programs create
a steady supply of recycled resins regardless of the ability of end-users to utilize
the material (Misner, 1991). Export of recycled plastics may assist in absorbing
the oversupply (Goldberg, 1990).
STEEL AND TIN VOLUMES AND MARKETS
Amounts
The broad category of ferrous metal scrap consists of all alloyed or unalloyed
ferrous materials containing iron or steel as the principal component (Schottman,
1985). In the model that Franklin Associates, Ltd. (1990) used to calculate MSW
ferrous metal scrap generation and recovery rates, only durable goods (e.g., white
goods, furniture, tires) and steel containers and packaging are considered. Durable
goods are usually collected separately from common recyclables and sent to
automobile processing facilities for shredding (U.S. EPA, 1989). This report
excludes durable goods and focuses instead on food and beverage containers.
In addition to iron and steel, tin can be a significant component of ferrous
scrap. The main source of tin in MSW is the tinplate that is used for steel food and
beverage containers. Excluding white goods and other durables, tinplated steel
B-15
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cans constitute the largest single source of ferrous metal scrap (approximately 60
percent) recovered from MSW (personal communication between TRC
Environmental Corporation and Gregory L. Crawford of the Steel Can Recycling
Institute on August 13, 1991). The remaining 40 percent falls into a category
called other ferrous scrap, which may include a number of discarded items such as
old, broken, or worn out toys, tools, and automobile parts.
According to Franklin Associates, Ltd. (1990), approximately 11.6 million
tons of ferrous metals in MSW (including durable goods as well as steel containers
and packaging) were generated in 1988, of which an estimated 400,000 tons was
recovered from steel containers and packaging (Table B-6) (Franklin Associates,
Ltd., 1990). This figure indicates a recycling rate of 13.8 percent for steel
containers and packaging. The Steel Can Recycling Institute (Heenan, 1991)
reported that the steel-can recycling rate for 1990 had increased to 24.6 percent.
Markets
In general, ferrous metals markets are the most established of all recyclable
markets. Ferrous metals have been recycled for more than 50 years into a variety
of products. Most steel industry experts expect the domestic market for recycled
steel cans to be consistent because of continued growth in the scrap-consuming
minimill sector of the steel industry (Goldberg, 1990). It is expected that this
growth will accommodate anticipated increases in the amount of steel cans
collected from MSW.
B-16
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TABLE B-6
Generation and Recycling of Ferrous Metal in MSW, 1 988a
Product category
Weight
generated
(in million
of tons)
Weight
recovered
(in million
of tons)
Percent
recovered
Discards
(in million
of tons)
Durable goods
Ferrous metalsb
8.8
0.3
3.4
8.5
Containers and packaging steel
Beer and soft drink cans
Food and other cans
,Other steel packaging
Total containers and
packaging steel
Total ferrous metals
0.1
2.5
0.2
2.8
11.6
Negligible
0.4
Negligible
0.4
0.7
Negligible
16.0
Negligible
16.0
6.0
0.1
2.1
0.2
2.4
10.9
aNumbers may not add to totals because of rounding.
bFerrous metals in appliances, furniture, tires, and miscellaneous durables.
Source: Franklin Associates, Ltd., 1990.
B-17
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APPENDIX C
FEDERAL, STATE, AND MUNICIPAL INVOLVEMENT
FEDERAL INVOLVEMENT
In response to the 1976 passage of the Resource Conservation and
Recovery Act (RCRA), EPA developed guidelines that outline requirements and
recommendations for the recycling activities of Federal agencies, state and local
governments, and the private sector.
Throughout the 1980s, EPA made several proposals to encourage the
establishment of recycling programs. In February 1988, EPA created the Municipal
Solid Waste Task Force to specifically address MSW problems and, 1 year later,
presented its suggestions in a final report titled The Solid Waste Dilemma: An
Agenda for Action. The task force recommendations are summarized in the
concept of "integrated waste management." This concept encourages recycling as
the preferred waste management option, second only to source reduction. EPA,
therefore, established a national goal of 25 percent source reduction and recycling
by 1992. The guidelines EPA set forth to achieve this goal include the following:
• Stimulation of markets for secondary materials
• Enhancement of separation, collection, and processing of recyclables
• Establishment of a national recycling council
• A review of the incentives and disincentives of liability potentially
affecting recycling industries
The report suggested that all levels of government and the private sector
participate in establishing these guidelines to achieve the 25 percent source
reduction and recycling goal (U.S. EPA, 1989).
C-1
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Aside from EPA, other Federal agencies also have begun to address recycling
issues. The U.S. Food and Drug Administration continues to evaluate the use of
recycled plastic in food packaging materials.
STATE INVOLVEMENT
Because RCRA placed the responsibility for MSW management on state
governments, the majority of laws passed in the United States regarding recycling
have occurred on the state level. An annual nationwide survey conducted by the
journal Biocycle indicates that the first state law to have a significant effect on
recycling efforts was Oregon's "Opportunity to Recycle " Act of 1983 (Glenn and
Riggle, 1991). This law banned many recyclables from landfills and incinerators
and required municipalities to provide recycling services. Connecticut, Rhode
Island, and New Jersey passed similar legislation several years later. In addition to
the requirements mentioned above, Rhode Island and New Jersey mandated citizen
and business participation. State recycling laws proliferated between 1987 and
1989, with 22 states enacting comprehensive recycling laws (National Solid Waste
Management Association [NSWMA], 1989). NSWMA defines a comprehensive
recycling law as one providing a framework for statewide recycling and mandating
local government and citizen participation in some cases.
In 1990, new recycling legislation focused less directly on recycling and
more on waste reduction goals. Requirements of various laws can be separated
into three categories. The first type requires local governments to pass ordinances
mandating citizens and businesses to source separate and recycle. Connecticut
joined the District of Columbia, New Jersey, New York, Pennsylvania, and Rhode
Island in enacting this type of law. The second type of legislation requires
municipalities to provide recycling programs without making participation
mandatory. Arizona was the only state to pass such legislation in 1990, joining
nine other states that already had such laws. The third type, which is generally
combined with one of the first two types, requires municipalities to reach a
specified waste reduction goal. Alabama, California, Maryland, Minnesota, North
C-2
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Carolina, Vermont, and Virginia added this type of legislation to mandatory source
separation ordinances. New Jersey and Rhode Island added goals to mandatory
participation requirements. Florida, Georgia, Illinois, Iowa, Louisiana, and Ohio
passed waste reduction goals alone (Glenn and Riggle, 199.1). Table C-1 lists state
recycling goals as well as whether the states have made these goals mandatory
and the deadlines for meeting goals.
Land disposal bans are another method states use to encourage recycling of
MSW. In 1990, only Massachusetts and Wisconsin passed land disposal bans on
traditional constituents of MSW. Connecticut removed disposal bans in favor of
mandating recycling of the once-banned items.
Aside from mandating the establishment of recycling programs, many states
encourage recycling by financing market development. Four types of financial
incentives exist: tax credits, low-interest loans, grants, and tax exemptions. As
the promulgation of new recycling legislation waned in 1990, so did the enactment
of financial incentives for market development. Virginia was the only state to
enact a tax credit program in 1990, joining California, Colorado, Maryland, New
Jersey, North Carolina, and Oregon. Low-interest loan provisions were enacted in
California and Wisconsin, bringing the total number of states with such provisions
to 11. As of 1990, 10 states have grant provisions with Virginia and Wisconsin
being the most recent additions. In total, 19 states provide some type of financial
incentive for market development (Glenn and Riggle, 1991).
Another way in which states can encourage market development is to
establish procurement guidelines for the purchase of products made with some
fraction of recycled feedstock. By the end of 1990, 34 states had procurement
legislation enacted and another 3 had executive orders passed.
A dilemma shared by many states following enactment of recycling
legislation is finding the funding to support budgets for the various programs. In
states that depend on general tax revenues, the current recession has made
implementation difficult. Fifteen states have some form of disposal tax or
C-3
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TABLE C-1
State Recycling Goals
State
Alabama
California
Connecticut
District of
Columbia
Florida
Georgia
Illinois
Indiana
Iowa
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
New Hampshire
i —
New Jersey
New Mexico
New York
North Carolina
Ohio
Recycling goal3
NS
NS
25%
45%
30%b
NS
25%
50%b
50%
NS
50%
15-20%
25%
20-30%
25-35%
NS
NS
NS
25%
NS
40-42%
NS
25%
Mandate
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Deadline
1991
2000
1991
1994
1995
1996
2000
2000
2000
1992
1994
1994
2000
2005
1993
1996
1998
2000
1990
2000
2000
1993
1994
C-4
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TABLE C-1 (continued)
State
Pennsylvania
Rhode Island
Vermont
Virginia
Washington
Recycling goal3
25%
15%
NS
25%
NS
Mandate
Yes
Yes
No
Yes
Yes
Deadline
1997
1993
2000
1995
1995
Includes yard waste composting (except for New Jersey),
Includes source reduction.
NS = Not specified.
Source: Glenn and Riggle, 1991.
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collection fee in place to fund programs. New Mexico enacted a 0.12 percent tax
on business gross receipts in 1990 to fund its recycling program.
t
MUNICIPAL INVOLVEMENT
The success of state recycling programs requires that municipalities take an
active role in researching, planning, and implementing programs that meet their
specific community and regional needs. Municipalities in turn look to state
agencies for information and funding and to recycling organizations for information
and support.
The increase in municipal recycling programs nationwide is reflected in the
growth of state recycling organizations, which have experienced more than a 50
percent increase in membership in the last 3 years (Apotheker, 1992). These
organizations comprise individuals, businesses, nonprofit groups, and governments.
Their efforts concentrate on disseminating information on recycling issues to their
membership and the public. The newly formed Southern States Recycling
Coalition, which represents individuals from 16 states and Puerto Rico, has
established objectives that include seeking to develop, stimulate, and stabilize
markets for recyclables and to promote effective recycling methods (Ramay, 1992).
To better characterize local programs, the Municipal Waste Management
Association, an affiliate of the U.S. Conference of Mayors, conducted a survey of
the 163 cities applying for the Heinz National Recycling Awards Program (U.S.
Conference of Mayors, 1991). Although all 163 cities have recycling programs,
more than 80 percent responded that landfilling and energy recovery through
combustion were still their predominant methods of solid waste disposal. Sixty-
nine percent of the cities landfilled more than 50 percent of their MSW, whereas
2 percent of the cities reported combusting for energy recovery more than 50
percent of their MSW. Of the 163 cities, 104 reported marked increases in the
cost of traditional MSW disposal methods. The survey noted the correlation
between increased disposal costs and an increase in the number of recycling
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programs; more than 65 percent of the responding cities started their programs
within the last 3 years.
The survey also gathered information on the types of recycling programs
implemented and the key recycling issues facing cities in the next 5 years. For
residential customers, 87 percent of the cities operate curbside collection systems,
68 percent operate drop-off facilities, and 27 percent operate buy-back centers.
Many cities offer more than one type of program and offer services to multifamily
dwellings. The key issues facing cities, in descending order of importance follow:
Market development and stability for recyclables
Cost and funding of programs
Development of waste reduction
Public education
Establishing local ordinances and requirements
Enforcement of recycling ordinances
Purchasing recycled products
Increased public participation
Improved technology
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APPENDIX D
BIBLIOGRAPHY ON
MUNICIPAL SOLID WASTE MANAGEMENT OPTIONS
LANDFILLS
Bingemer, H.; Crutzen, P. (1987). The production of methane from solid wastes.
J. Geophysical Research. 92 (D2): 2181-2187.
Dwyer, J. R., et al. (1986). Evaluation of municipal solid waste landfill cover
designs. U.S. EPA, Hazardous Waste Engineering Lab, Cincinnati, OH. PB88-
171327.
Lu, J.C.S.; Eichenberger, B.; Stearns, R. J. (1985). Leachate from municipal
landfills, production and management. Park Ridge, NJ: Noyes Publications.
Pohland, F. G.; Harper, S. R. (1987). Critical review and summary of leachate and
gas production from landfills. U.S. EPA, Hazardous Waste Engineering Research
Laboratory. EPA/600/S2-86-073.
U.S. Congress. (1989). Facing America's trash. What next for municipal solid
waste? Office of Technology Assessment. OTA-O-424.
U.S. EPA. (1986). Critical review and summary of leachate and gas production
from landfills. PB86-240181/XAB.
U.S. EPA. (1988). Summary of data on municipal solid waste landfill leachate
characteristics; Criteria for municipal solid waste landfills (40 CFR Part 258).
Office of Solid Waste. EPA/530-SW-88-038.
U.S. EPA. (1989). The solid waste dilemma: an agenda for action. Office of
Solid Waste, Washington, DC.
U.S. EPA. (1989). Decision-makers guide to solid waste management. Solid
Waste and Emergency Response. EPA/530-SW-89-072.
U.S. EPA. (1991). Criteria for municipal solid waste landfills (40 CFR Part 258; 56
FR 51016, October 9, 1991). Office of Solid Waste.
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INCINERATION
Brna, T. G. (1988). State-of-the-art flue gas cleaning technologies for municipal
solid waste combustion. U.S. EPA, Air and Energy Engineering Research Lab,
Research Triangle Park, NC. PB88-184601/XAB.
Denison, R. A.; Silbergeld, E. K. (1989). Comprehensive management of
municipal solid waste incineration: understanding the risks. Toxic Chemicals
Program. Environmental Defense Fund, Washington, DC.
Hahn, J. L.; Sussman, D. B. (1988). Municipal waste combustion ash: testing
methods, constituents and potential risks. Resource Recovery. 2(5):16-18.
National League of Cities. (1986). Waste-to-energy facilities: a decision maker's
guide. Washington, DC.
Penner, S. S.; Wiesenhahn, D. F.; Li, C. P. (1987). Mass burning of municipal
wastes. Ann. Rev. Energy. 12:415-444.
Radian Corporation. (1989). Database of existing municipal waste combustion
studies. Database maintained for the U.S. Environmental Protection Agency;
Research Triangle Park, NC.
U.S. EPA. (1987). Characterization of municipal waste combustor ashes and
leachates from municipal solid waste landfills, monofills, and co-disposal sites.
Office of Solid Waste. PB88-127980/XAB.
U.S. EPA. (1987). Municipal waste combustion study, report to Congress.
Washington, DC. EPA/530-SW-87-021a.
U.S. EPA. (1987). Municipal waste combustion study: assessment of health risks
associated with municipal waste combustion emissions. EPA/530-SW-87-02.
U.S. EPA. (1987). Municipal waste combustion study, characterization of the
municipal waste combustion industry. EPA/530-SW-87-021h.
U.S. EPA. (1987). Municipal waste combustion study, emission data base for
municipal waste combustors. EPA/530-SW-87-021b.
COMPOSTING
BioCycle. (1988). Composting projects for grass clippings. BioCycle. 29(5):47.
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The BioCycle guide to composting municipal wastes. BioCycle. January 1989.
Connecticut Department of Environmental Protection. (1989). Leaf composting - a
guide for municipalities. DEP, Local Assistance and Program Coordination Unit,
Recycling Program; Hartford, CT.
Ernst, A. A. (1988). 30 years of refuse/sludge composting. BioCycle. 29(6): 34-
35.
Finstein, M. S.; Miller, F. C.; Strom, P. F. (1986). Monitoring and evaluating
composting process performance. J. Water Pollut. Control Fed. 58: 272-278.
Illinois Department of Energy and Natural Resources. (1987). Economics and
feasibility of co-composting solid wastes in McHenry County (Illinois). Springfield,
IL: Illinois Department of Energy and Natural Resources Clearinghouse. ILENR/RE-
EA-78-12.
Massachusetts Department of Environmental Quality Engineering. (1988). Leaf
composting guidance document. DEQE, Boston.
Mayer, M.; Hofer, H.; Maire, U. (1988). Trends in yard waste composting.
BioCycle. 29(6): 60-63.
Ron Albrecht Associates, Inc. (1988). Composting technologies, costs, programs
and markets. Report prepared for U.S. Congress, Office of Technology
Assessment.
Rosen, C. J.; Schumacher, N.; Mugaas, R.; Proudfoot, S. (1988). Composting
and mulching: a guide to managing organic wastes. Minnesota Extension Service
Report. AG-FO-3296.
Taylor, A. C.; Kashmanian, R. M. (1989). Study and assessment of eight yard
waste composting programs across the United States. U.S. Environmental
Protection Agency. EPA/530-SW-89-038.
D-3 *U.S. GOVERNMENT PRINTING OFFICE: 1994 - 550-001/80396
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