Thermal Desorption Treatment 1
Thermal desorption is an ex situ means to physically separate volatile and some semivolatile contaminants from soil, sediments, sludges, and filter cakes by heating them at temperatures high enough to volatilize the organic contaminants. For wastes containing up to 10 percent organics or less, thermal desorption can be used in conjunction with off-gas treatment for site remediation. It also may find applications in conjunction with other technologies at a site.
Thermal desorption is applicable to organic wastes and generally is not used for treating metals and other inorganics. The technology thermally heats contaminated media, generally between 300 to 1,000°F, thus driving off the water, volatile contaminants, and some semivolatile contaminants from the contaminated solid stream and transferring them to a gas stream. The organics in the contaminated gas stream are then treated by being burned in an afterburner, condensed in a single- or multistage condenser, or captured by carbon adsorption beds.
The use of this well-established technology is a site-specific determination. Thermal desorption technologies are the selected remedies at 31 Superfund sites . Geophysical investigations and other engineering studies need to be performed to identify the appropriate measure or combination of measures to be implemented based on the site conditions and constituents of concern at the site. Site-specific treatability studies may be necessary to establish the applicability and project the likely performance of a thermal desorption system. The EPA contact indicated at the end of this chapter can assist in the identification of other contacts and sources of information necessary for such treatability studies.
This chapter discusses various aspects of the thermal desorption technology including applicability, limitations of its use, residuals produced, performance data, site requirements, status of the technology, and sources of further information.