FUNDAMENTAL STUDIES OF THERMAL DESORPTION OF CONTAMINANTS FROM SOIL

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Chemical and physical processes by which mutagens are destroyed, removed, sequestored, and generated during thermal treatment of contaminated soils will be studied using soils and conditions commonly encountered at Superfund Sites such as found in the Aberjona Basin. Specific objectives are to determine, for practically revelant temperatures, heating rates, treatment times, and contaminant concentrations, how rates and extents of mutagens removal or destruction, and the mutagenicity of the resulting residues, are affected by thermal desorption, in situ thermal decomposition, secondary chemical transformations, external treating agents (e.g. lime), and by in situ carbon formation leading to permanent or temporary sequestration of heteroatoms (e.g. halogens or metals). The research is important to environmental health sciences and to the Superfund Program because: soil remediation is critical to Superfund; various methodologies based on in situ or off-site thermal treatment show promise for effective remediation of Superfund soils; contaminants are complex mixtures including mutagenic and/or carcinogenic organics and metals; there is need to identify conditions for which thermal treatment removes or destroys mutagens and other contaminants, without generating toxicants that recontaminate the soil or air. The approach is to use small scale apparatus designed to simulate practical scale operating conditions and allow systematic study of how key chemical and physical processed (e.g. desorption) contribute to mutagens formation and destruction rates. Deliverables will be data bases and parameterized kinetic models for mutagens destruction, removal, and secondary formation, during thermal treatment of soil. Benefits will be better scientific and engineering foundations for the design and operation of environmentally sound thermal soil remediation processes, e.g., thermal stripping, plasma heating, incineration, and in situ heating with microwaves.