27-09-2010, 12:11 PM
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Plasma Arc Treatment of Municipal and
Hazardous Wastes
Catherine Bodurow, USEPA/OPPTS/OPPT/RAD
Louis J. Circeo, Kevin C. Caravati, Robert C. Martin, Michael S. Smith
Georgia Institute of Technology - Georgia Tech Research Institute
abstract
Plasma treatment of waste materials offers a solution that could effectively and safely dispose of municipal, hazardous, and toxic wastes that are generated by the residential, commercial, and industrial sectors of our economy. Plasma arc technology uses electricity to create a form of artificial lightning with temperatures exceeding 7,000° C, which is up to three times hotter than fossil fuels. These sustained high temperatures, hotter than the surface of the sun, cause the organic compounds in the wastes to completely dissociate into their elemental components. These recombine as fuel gases and simple acid gases that are quenched and cleaned in a gas scrubber system.
The inorganic components in the waste are melted and vitrified into a glassy, rock-like solid residue, which is highly resistant to leaching. Both gas and solid by-products are potentially recyclable as useful fuel gases and road gravel. If electricity is produced from the fuel gases, about 40% would be used to operate the plasma torches and the plant, and the remaining 60% could be sold to the electric grid. Furthermore, the requirements for municipal or industrial waste landfills are eliminated. At throughput volumes of up to 1,000 tons per day, plasma arc system capital costs are about the same as traditional incineration technology. However, the advantages of plasma systems over incinerators are numerous. Prototype facilities for the plasma treatment of municipal solid waste, incinerator ash, asbestos, and medical waste have been successfully demonstrated and commercialized.
Recent technological advances in plasma arc technology permit the in situ transformation of most soil, rock, and waste types into a vitrified, rock-like material similar to obsidian that is durable, strong, and highly resistant to leaching. A plasma arc torch can be lowered into a borehole to any depth and be operated to pyrolyze or gasify municipal wastes and any contaminated soils. The
plasma torch is slowly raised and operated at progressively higher levels to thermally convert buried wastes into a vertical column of
vitrified and remediated rock-like material. In situ plasma vitrification (ISPV) would be directly applicable to all subterranean waste deposits such as municipal landfills, hazardous/toxic waste deposits, buried debris, sediments and sludges, radionuclides, and underground storage tanks.
