MANAGEMENT OF SOLID WASTE 647
of miscellaneous waste matter resulting from maintenance
and general housekeeping.
Most crop waste is either plowed back into the soil or
composted. Some open burning takes place. In some special
cases such as bagasse (sugar cane stalks) industries have been
established to utilize the waste material. Essentially none of
this material finds it way into the usual disposal facilities.
Animal wastes pose a different problem because much
is produced in very concentrated areas such as feed lots
or poultry farms. The disposal of these wastes is posing a
greater problem than crop waste, but may be more easily
solved because it is concentrated and therefore susceptible
to processing without collection. Average waste yields for a
variety of domestic animals are summarized on Table 11.Mineral WastesMineral wastes including solids generated in mining, milling
and processing industries are expected to reach between two
and four billion tons per year in 1990. In 1965 this waste
amounted to 1.4 billion tons, as summarized in Table 12.Hazardous WastesHazardous wastes as defined by the federal government and
in many cases similarly by the states, must be receiving spe-
cial handling. These wastes generally include materials that are
injurious to human health, toxic, can cause irreversible environ-
mental damage, such as high concentrations of pesticides, are
corrosive, reactive (form toxic gases), or highly inflammable.
These wastes are defined in Federal Regulations (40CFR261).
They require special management from generation through
treatment and disposal as defined again by Federal Regulations.
A detailed discussion of Hazardous Waste Management is cov-
ered in a section on Hazardous Waste.Processing MethodsA variety of processing methods, as summarized in Table 13,
are available at present for handling solid wastes. Most have
been in use in some modification for at least the last 50 years.
The choice of processing method will depend not only on
the type of waste but also on location, sources, quantity of
waste, method of collection, public opinion, and ultimately
economics.
Solid waste management was a 4.5 billion dollar indus-
try in 1968. It is only in recent years that the public has
begun to worry about disposal of solids. Prior to that it was
“out-of-sight, out-of-mind.” With ever growing amounts of
solid waste as detailed in the discussion on sources, and con-
cerns about pollution of ground and drinking water as well
as release of hazardous materials, public pressure is becom-
ing a major factor in any decision on waste management.
The major disposal methods in use are landfill and incin-
eration. Of potential interest in the United States are high pres-
sure compaction and reclamation by recycling. Recycling is
being used, but requires solution of institutional and techno-
logical barriers before becoming a major factor. Compaction
is utilized in at least one major facility in the Meadowlands in
New Jersey. Composting is practiced in Europe, but also has
not been successfully applied in the United States although it
does have potential. There are new processes and techniques
appearing for waste disposal and for the first time an organized
research and development effort was mounted in the early ’70s
to look at solid waste disposal; it has slowed down but there is
ample opportunity for further progress.
Disposal methods could be discussed from the point
of view of source: a brief summary of the most used meth-
ods for a variety of sources may be found in Table 14. This
discussion will instead focus on the disposal methods most
commonly in use today, landfill and incineration, followed
by discussion of compaction, composting, and some of the
newer disposal techniques.
The oldest method of disposal is dumping either on land
or sea. Here dumping in distinguished from Sanitary Landfill
(see below). Dumping costs between $6 and $10 per ton and
has been used for all waste materials. It is totally unsatisfac-
tory for putrescible materials such as food wastes and unsatis-
factory from a public health as well as aesthetic and land use
viewpoint, even for inert material such as demolition waste.
Open burning is often used for demolition waste, tree
branches and stumps, and similar items; it is unacceptable
because of the air pollution it creates. Neither dumping nor
open burning have a place in the modern waste disposal
scheme and are illegal.Sanitary Landfi llLandfill is the most widely used method of waste disposal.
There are 8900 authorized sites (about half publicly oper-
ated) used by the 6300 communities surveyed in 1968.^14 There
appeared to be an equal number of unauthorized dumps. Unfor-
tunately only 6% of the sites were considered to be “truly”
sanitary. The remainder fell either into Category B or C on the
US Public Health Service Classification Scale, summarized inTABLE 4
Municipal refuseB ultimate chemical analysisConstituents % by weight (as received)Proximate Analysis —
Moisture 15–35
Volatile matter 50–65
Fixed carbon 3–9
Noncombustibles 15–25
Ultimate analysis —
Moisture 15–35
Carbon 15–30
Oxygen 12–24
Hydrogen 2–5
Nitrogen 0.2–1.0
Sulfur 0.02–0.1
Chloride 0.3–0.5 (16)
Noncombustibles 15–25
Heating values, Gross 3000–6000 Btu/1bC013_002_r03.indd 647C013_002_r03.indd 647 11/18/2005 2:27:18 PM11/18/2005 2:27:18 PM