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Engineering Technical Support Center (ETSC)

Thermal Technologies 

Thermal Technologies
  • Biological Technologies
  • Physical/Chemical Technologies
  • Thermal Technologies
    Thermal treatments employ heat to vaporize and collect contaminants for safe disposal. Thermal treatments are mostly used in locations high in organic material, rather than to treat mining contamination. Given the complex nature of thermal systems, they are active treatment systems.

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Thermal Desorption (TD)

ETSC assists thermal desorption studies.
ETSC assists thermal desorption studies.

Thermal desorption uses heat to transform chemicals into gases for collection, after they go through a process that removes a targeted substance according to the principles of adsorption-desorption. TD is most useful to clean soils polluted by coal tar, solvents, and wood-preserving chemicals and can be a fast, effective method of cleaning heavily polluted soils. For more information about TD, see A Citizen's Guide to Thermal Desorption (PDF) (2 pp, 65K, EPA/542/F-01/003).

Electrical Resistance Heating

Electrical resistance heating passes an electrical current through moist soil to heat the area and vaporize contaminants for collection and treatment. The soil's resistance produces the polluted heat and steam, and an SVE system most often captures the removed contaminants.

Steam Injection

This process involves the introduction of steam into the ground for the purpose of increasing the vapor pressure of the volatile contaminants in the soil. These contaminants then become part of the air/water vapor that rises to the soil's surface. The vapors are then collected, condensed through cooling, and treated. Variables such as soil permeability and chemical volatility may limit steam injection's ability to remove contaminants.

Conductive Heating

Conductive heating uses heating blankets or heating wells (i.e. steel pipes) to vaporize water; the vaporized water carries contaminants to the surface for collection and subsequent treatment.

Thermal technologies use heat.
Thermal technologies use heat.

Radio-Frequency Heating

Electrodes placed in the soil create a high-frequency, alternating electric field that heats the area, and a vapor extraction system (using SVE wells) collects the harmful substances for treatment. A grounded, metal buffer over and around the area prevents local radio interference and assures safe operation for neighboring communities.

Vitrification

Melt parts of soil? Sounds crazy, but one active thermal technology sends high voltages into the ground, heating and melting targeted substances. Stable glass or crystalline solids then form, capturing and encapsulating—literally vitrifying—the harmful substances. The gases produced are then captured by a hood for further treatment.

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