Contaminants that Can Be Treated

Electron donors can enhance the bioremediation of chlorinated solvents, such as chloroethenes, chloroethanes, and chloromethanes that are dissolved in ground water.  The most common chlorinated solvents include tetrachloroethene (PCE, or perchloroethene), trichloroethene (TCE), trichloroethane (TCA), and carbon tetrachloride (CT).  Other common ground water contaminants that are subject to reduction reactions are also susceptible to enhanced anaerobic bioremediation.  Many of the techniques to create anaerobic reactive zones for chlorinated solvents may also apply enhanced anaerobic bioremediation of the following constituents:  1. Chlorobenzenes; 2. Chlorinated pesticides (e.g., chlordane), polychlorinated biphenyls (PCBs), and chlorinated cyclic hydrocarbons (e.g., pentachlorophenol); 3. Oxidizers such as perchlorate and chlorate; 4. Explosive and ordnance compounds; 5. Dissolved metals (e.g., hexavalent chromium and hexavalent uranium); and 6. Nitrate and sulfate (AFCEE, 2004, US EPA, 2000).
 

Compounds such as chlorinated solvents exist in an oxidized state and therefore are usually not susceptible to aerobic oxidation.  However, such oxidized compounds are susceptible to anaerobic reduction.  In recent years, efforts have been made to enhance natural anaerobic processes through the injection of electron donors such as emulsified vegetable oils (EVO) into the subsurface.  An overview of these technologies was reviewed by US EPA (2000).