Reductive Dehalogenation

Larry N. Britton

Widespread use of degreasing solvents like tetrachloroethene (PCE) and trichloroethene (TCE) has left a legacy of subsurface contamination. One of the strategies for remediation of contaminated sites is biological reductive dehalogenation whereby soil microorganisms sequentially remove chlorine atoms from the compounds in a reductive pathway under anaerobic conditions. However, in heavily contaminated source zones the rates of biological dehalogenation often are nil because of inhibitory effects.

 Reductive DehalogenationWe are developing a chemical approach that borrows on biological mechanisms that include use of transition metal-containing, oxidation/reduction (redox) catalysts and reductants. Straight-forward, rapid dehalogenation of chlorinated solvents can be achieved with select redox catalysts and reductants, and this chemical approach can be used in source zones where the solvents exists as dense non-aqueous phase liquids (DNAPL).

The research seeks to discover highly effective, environmentally-acceptable catalysts and other chemicals that can be injected into the contaminated sites to achieve cleanup. It is important to understand the mechanisms and issues related to the flow and transport of the remediation fluids to the subsurface sites such that the entire remedial process can be reliably engineered.