Page 37 - Materials Chemistry, Second Edition

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8 Waste Management Practices: Municipal, Hazardous, and Industrial
D landfills accept many kinds of wastes, and not just MSW. Household items such as old newspa-
pers, food waste, plastic packaging and refrigerators may be present along with construction and
demolition debris. It has been a common practice to landfill nonhazardous industrial wastes, such
as those from the oil and gas industry, as well as residues from automobile salvage operations, along
with MSW. About 16% of municipal landfills are used for the disposal of sewage sludges
(“biosolids”) from wastewater treatment plants (Tammemagi, 1999). Such co-disposal practices are
fairly common, because wastewater treatment plants are often owned and operated by the same
municipal body, thus encouraging cooperation between the two facilities. Finally, MSW landfills
contain a significant proportion of potentially hazardous materials from homes. Households gener-
ate used motor oil, pesticide and paint containers, batteries, household solvents, and many other
hazardous wastes, albeit in small volumes.

1.2.2 HAZARDOUS WASTE

Hazardous wastes are produced by most, if not all, of the sources listed in Table 1.1. However, when
the monthly quantity generated exceeds a certain limit, both the wastes and the generator are subject to
compliance with federal and state regulations. RCRA defines hazardous waste as (40 CFR 240.101):
Any waste or combination of wastes which pose a substantial present or potential hazard to human
health or living organisms because such wastes are non-degradable or persistent in nature or because
they can be biologically magnified, or because they can be lethal, or because they may otherwise cause
or tend to cause detrimental cumulative effects.

In other words, an RCRA hazardous waste is a solid waste that, owing to its quantity, concen-
tration, or physical, chemical or infectious characteristics, may (1) cause or contribute to an increase
in mortality, serious illness, or incapacitation or (2) pose a substantial hazard to human health or the
environment when improperly treated, stored, transported or disposed of, or otherwise managed.
Solid wastes are classified as hazardous under the RCRA regulations if they exhibit one or more
of the following characteristics:

● Ignitability
● Corrosivity
● Reactivity
● Toxicity
Examples of hazardous wastes include residues from solvent manufacture, electroplating, metal
treating, wood preserving, and petroleum refining. Regulations require that these wastes be managed
much more stringently as compared with ordinary MSW. For example, an extensive “paper trail” is
required, indicating the status of the waste from the point of generation, through interim storage, treat-
ment (if any), transportation, and ultimate disposal. Requirements are stringent for facilities that gen-
erate waste, as well as for transporters, and treatment, storage and disposal facilities. This “cradle to
grave” approach to handling hazardous wastes has been central to promoting sound management.

1.2.3 INDUSTRIAL WASTE

Billions of tons of industrial solid waste are generated and managed on-site at industrial facilities
each year; the amount generated is approximately four times greater than the amount of MSW pro-
duced (Tammemagi, 1999). Generated by a broad spectrum of U.S. facilities, industrial wastes are
by-products from manufacturing and other processes. Many (but not all) of these wastes are of low
toxicity and are usually produced in fairly large quantities by an individual generator. Examples of
an industrial waste stream are coal combustion solids, including bottom ash, fly ash, and flue gas
desulfurization sludge. Other common sources of industrial wastes are the pulp and paper industry,
the iron and steel industry, and the chemical industry.