In situ thermal desorption (ISTD) is an intensive thermally enhanced
environmental remediation
Environmental remediation deals with the removal of pollution or contaminants from environmental media such as soil, groundwater, sediment, or surface water. Remedial action is generally subject to an array of regulatory requirements, and may al ...
technology that uses thermal conductive heating (TCH) elements to directly transfer heat to environmental media. The ISTD/TCH process can be applied at low (<100 °C), moderate (~100 °C) and higher (>100 °C) temperature levels to accomplish the remediation of a wide variety of contaminants, both above and below the water table. ISTD/TCH is the only major in situ thermal remediation (ISTR) technology capable of achieving subsurface target treatment temperatures above the boiling point of water and is effective at virtually any depth in almost any media. TCH works in tight soils, clay layers, and soils with wide heterogeneity in permeability or moisture content that are impacted by a broad range of volatile and semi-volatile organic contaminants.
History
ISTD using TCH was developed by Shell Oil Co. in the late 1980s and grew out of research and development for
enhanced oil recovery
Enhanced oil recovery (abbreviated EOR), also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. EOR can extract 30% to 60% or more of a reservoir's oil, compared to 20% to 40% using ...
. During the mid-1990s
Shell Oil Company
Shell USA, Inc. (formerly Shell Oil Company, Inc.) is the United States-based wholly owned subsidiary of Shell plc, a UK-based transnational corporation " oil major" which is amongst the largest oil companies in the world. Approximately 18,000 ...
commercialized ISTD with an investment of over $30 million.{{fact, date=March 2020
Method of operation
Thermal conductive heating is the application of heat to subsurface soils through conductive heat transfer. The source of the heat is applied via electric or gas powered thermal wells. Thermal wells are inserted vertically, or horizontally, in an array within the soil. Heat flows from the heating elements by conduction. The heating process causes contaminants to be vaporized or destroyed by means of:
# evaporation
# steam stripping
# hydrolysis
# oxidation
# pyrolysis
Vaporized contaminants are collected from vapor extraction wells and containerized for removal or recycling.
See also
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Soil vapor extraction
Soil vapor extraction (SVE) is a physical treatment process for in situ remediation of volatile contaminants in vadose zone (unsaturated) soils (EPA, 2012). SVE (also referred to as in situ soil venting or vacuum extraction) is based on mass tran ...
*
thermal blanket
A thermal blanket is a device used in thermal desorption to clean soil contamination. The primary function of a thermal blanket is to heat the soil to the boiling point of the contaminants (usually 100 to 325 °C and as high as 900 °C ...
References
Pollution control technologies
Soil contamination
Waste treatment technology