ABSTRACT
The natural bioremediation of chlorinated solvents depends on the appropriate subsurface environmental conditions. These conditions must promote growth of either anaerobic or aerobic microorganisms and allow for the contact between chlorinated solvent and these microbes. Microbially-mediated reactions of chlorinated solvents usually involve oxidation or reduction reactions. These reactions, oxidation for removal of electrons from chlorinated solvents and reductions for addition of electrons to chlorinated solvents, are dependent to some extent on the degree of chlorination of the chlorinated solvent and upon the redox conditions of the microorganisms. The dechlorination occurs under anaerobic conditions and results in less chlorinated, and often aerobically degradable, products. The sequential anaerobic/aerobic biodegradation of chlorinated organic compounds might be a viable treatment technology, either naturally or induced. As natural bioremediation of chlorinated compounds is controlled in part by the natural redox of the ground water, sites amenable to anaerobic reductive dechlorination require information regarding the ability of indigenous microbes to undergo anaerobioses.
