Enhanced Oxidative Bioremediation of cis-dichloroethene (cis-DCE) and Vinyl Chloride (VC) using Electron Shuttles

Abstract : Biogeochemical transformation is defined as "processes where contaminants are degraded by abiotic reactions with naturally occurring and biogenically-formed minerals in the subsurface" (AFCEE et al., 2008). These biogenically-formed minerals are created as a result of biogeochemical reactions typically under anaerobic iron- and sulfate-reducing conditions. Biogenically-formed minerals are particularly important because they are continuously replenished in the subsurface and have high surface area and reactivity. In situ biogeochemical treatment systems are defined as systems that capitalize and/or enhance such natural processes via engineered reaction zones in the subsurface. Examples of this application include permeable reactive barriers (e.g., biowalls) and injection of organic carbon (e.g., soluble electron donors or vegetable oil emulsions) into a contaminated aquifer with the specific purpose of creating biogenically-formed minerals. The use of organic carbon-based permeable reactive barriers for treating chlorinated ethenes is an emerging technology that has shown its potential to be a cost-effective method of treatment (AFCEE, 2008). A carbon-based substrate such as plant mulch or vegetable oil is used to promote in situ biogeochemical transformation of chlorinated solvents such as trichloroethene (TCE) and tetrachloroethene (PCE) into benign end products such as carbon dioxide, chloride ion, and water.