Data Summary of Municipal Solid Waste Management Alternatives. Volume 1: Report Text Page: 30 of 216
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in landfill volume permits reuse of the site, which is already zoned for land-
Combustion with Energy Recovery
Like landfilling, open burning has been used for centuries to dispose of waste. In the United
States, combustion of MSW to recover energy in the form of saleable electricity was first
practiced in about 1902, in New York City.
Many newer plants now recover energy. In modern plants, energy can be recovered in the
form of hot water, steam, and electricity, or in some combination of those three forms. Until the
1970s, MSW combustors included little, if any, air pollution control equipment. The units of the
1950s and 1960s were generally marked by bad odors and smoke. They were primarily operated
only to reduce the volume of the waste. Since the early 1970s, increasingly stringent environ-
mental controls have been applied; as a result, today's combustors produce less air pollution.
Two options commonly used for combustion are:
1. Mass burning
2. Preparation and combustion of refuse-derived fuel (RDF).
They differ in extent of pretreatment of the MSW before firing, the type of furnace used, and the
In a mass burn facility, pretreatment of the MSW includes inspection and simple separation
to remove oversized and noncombustible items and unacceptable components such as obviously
hazardous or explosive materials. The MSW is then fed into a combustor, where it is typically
supported on a grate or hearth. Air is fed below and above the grate to promote combustion.
Mass burn plants can be large facilities, with capacities of 3,000 tons of MSW per day or more;
however, they can be scaled down to handle the waste from smaller communities, and modular
plants with capacities as low as 25 tons per day have been built.
RDF production begins with inspection of the MSW, removal of bulky or hazardous waste,
and shredding of the remaining MSW. Noncombustible materials are often separated as well.
The shredded RDF is most frequently burned above a traveling grate. RDF preparation and
direct firing cannot be performed economically in small plants, and the minimum size of an RDF
plant tends to be large. If RDF is compressed into pellets or cubes, it can be used in existing,
conventional furnaces with grates. A few operating facilities now produce such pellets or cubes
at one location for sale or use at another.
The energy produced by both mass burning and RDF combustion is generally used for elec-
trical power generation. MSW combustion can thus eliminate the need to mine, burn, and dis-
pose of the residue of some of the coal or oil that would otherwise be used to generate electricity.
Regulatory requirements for control of MSW combustion have grown increasingly stringent
since they were first implemented in the 1970s. For both types of options, federal regulations
governing all facilities with capacities greater than 250 tons per day set limits on a range of
pollutants, including acid gases, metals, and dioxins/furans. The EPA is developing comparable
requirements for units with capacities of less than 250 tons per day. State and local requirements
may be more stringent and may apply to even smaller combustors. Current regulations for the
larger plants are more stringent than those governing fossil fuel plants.
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SRI International. Data Summary of Municipal Solid Waste Management Alternatives. Volume 1: Report Text, report, October 1992; Golden, Colorado. (https://digital.library.unt.edu/ark:/67531/metadc1310776/m1/30/: accessed May 25, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.