664 MANAGEMENT OF SOLID WASTE
stream (again not including that contained in the batteries
which are recycled) is as follows:- 65% lead acid batteries (primarily car batteries)
- 27% consumer electronics
- 4% glass and ceramics
- 2% plastics
The primary sources of cadmium in the municipal waste
stream (after recycling) are as follows:- 54% household batteries
- 28% plastics
- 9% consumer electronics
- 5% appliances
- 4% pigments
To the extent that the lead and cadmium in the products
listed above can be eliminated or replaced, substantial source
reduction may be achieved.^41
Recycling is the next preferred alternative in the hier-
archy of integrated waste management options. As noted
above, it generally involves the reuse of secondary materials
as a supplement to or wholly in place of virgin materials in
the production of various goods. Whether or not the mate-
rial is used to produce the same goods which were recycled
depends on a number of technical, economic, and aesthetic
considerations. For example, plastics such as polyethylene
tetraphthalate (or “PET”) are currently being recycled from
large relatively uncontaminated one and two liter beverage
containers. They are not, however, used to produce new plas-
tic containers which will be used in contact with food. This
limitation is not a constraint where other types of beverage
containers made from aluminum or glass are concerned.
Aside from composting, which is addressed below, recycling
generally takes place as an in-plant practice or after certain
consumer products are used.
Recycling of process waste from a variety of industrial
and/or manufacturing operations has been practiced for some
time on a discretionary basis. The decision to use or dispose
of the byproduct of a given process often involves techni-
cal considerations such as chemical or physical differences
between the raw materials otherwise used and the scrap mate-
rial available. Assuming that no technical impediments exist,
the decision about whether to recycle is one of economics.
There is no question that the higher disposal costs currently
being experienced have driven more industries to recycle
as a business decision. However, the types and amounts of
materials and the number of industries potentially involved
are beyond the scope of this document.
The recovery of materials from municipal waste streams
or so called “post consumer” recycling has experienced sub-
stantial gains over the past several years due to diminishing
disposal capacity and dramatic increases in tipping fees. At
least 18 states have recycling goals established in legislation
including the four mentioned above where recycling is man-
datory. The materials most commonly recycled include news-
papers, glass, aluminum cans and to a lesser extent, corrugatedcardboard, various ferrous and non-ferrous scrap metals, and
plastics. These materials are typically accumulated by private
citizens and businesses and either collected curbside sepa-
rately from the remainder of solid waste destined for disposal
or brought to centralized collection facilities. As a matter of
convenience and to maximize citizen participation, many
systems collect commingled glass and cans or commingled
glass, cans, and newspapers in a single container.
The value of the materials described has varied widely,
depending on the quantity of material available, expected
levels of contamination, and transportation distance to end
markets. Furthermore, the rush to recycle by more and more
communities has resulted in erratic markets for certain materi-
als. For example, newspaper, which would demand approxi-
mately $60 per ton as recently as 1987, is now worth $20 per
ton in some cases and is taken for no compensation in other
cases. Projections by some waste newspaper exporters indicate
a probable net cost of $25 per ton by 1990. While markets for
other materials have been less volatile than this, considerable
variations have occurred. As of this writing, typical values per
ton for other recycled commodities are as follows:- aluminum $800
- Plastic PET bottles $120
- glass $40
- steel cans $10
Composting of vegetative waste is also a form of recycling.
It has become more widespread as landfill disposal costs have
risen. Leaves and other yard waste are amenable to this process,
which has proven more troublesome for grass clippings due
to the anaerobic odors often associated with grass not mixed
adequately to limit the development of such conditions.
Incineration of municipal solid waste has become
more widespread with new plants almost always incorpo-
rating steam generation and electrical power production.
Waterwall, or mass-burn incineration has become the tech-
nology of choice among those communities whose overall
management strategies include large scale volume reduction
processes after source reduction and recycling operations
have been utilized to maximum advantage and prior to sani-
tary landfilling of residuals or noncombustible materials.
Currently, 126 such facilities operate in 37 states. The aver-
age design capacity of these facilities is 814 tons per day.
Total design capacity for all these facilities is 68,399 tons per
day. This latter figure is projected to reach 107,832 tons per
day by 1992 when all facilities currently under construction
are completed and operational. The largest incinerators cur-
rently operating are a 3,300 tons per day plant in Michigan
and a 3,000 tons per day plant in Florida. There are also
124 modular plants currently in operation. These modular
plants are similar to mass burn plants but generally smaller
and sold as prefabricated units. The average modular plant
burns 124 tons per day.^42
While the process description of incineration remains as
described in the full text, significant design improvements and
air pollution control methodologies have been applied to new
facilities. The designs are all based on facilities establishedC013_002_r03.indd 664C013_002_r03.indd 664 11/18/2005 2:27:22 PM11/18/2005 2:27:22 PM