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ITRC ISB Team operated from 1995-2003 and produced eight documents. The document contains information that may not provide current best practices for evaluating or implementing the specified technology or may no longer be supported by current regulations. Therefore, access to the document has been removed from the ITRC website. If you are interested in reviewing the following archived document, please email ITRC at firstname.lastname@example.org.
In Situ Bioremediation (ISB) is the biological treatment of contaminants in the subsurface, typically in groundwater. ISB melds an understanding of microbiology, chemistry, hydrogeology, and engineering into a cohesive strategy for planned and controlled microbial degradation of specific classes of organic. ISB creates subsurface environmental conditions, typically through manipulation of the degree of oxidation or reduction, which induces the degradation of chemicals via microbial-catalyzed biochemical reactions. To accomplish this chain of events, the following aspects must be considered:
- type of microorganisms
- type of contaminant
- geological conditions at the site
ISB of chlorinated solvents in groundwater involves the input of an organic carbon source, nutrients, electron acceptors, and/or microbial cultures to stimulate degradation. ISB systems may be used to remediate high-concentration areas within plumes or, in some cases, source areas, to help provide containment of a chlorinated solvent plume, or as part of a treatment train downgradient from a primary cleanup or containment system. The major biological processes by which chlorinated solvent compounds degrade include anaerobic reductive dechlorination, aerobic co-metabolism, and oxidation.
A key factor in the design of ISB systems is the delivery mechanism of the various amendments to the targeted portion of the groundwater plume. Different types of delivery mechanisms have been used, including vertical well recirculation, horizontal well recirculation, filtration trench recirculation, direct liquid amendment injection, gas amendment injection, and pass-through or reactive cell designs.