Abiotic trichloroethylene dehalogenation using sodium hydrosulfite: Laboratory and field investigation

A microcosm study and field study were undertaken to investigate the feasibility of using the reducing agent sodium hydrosulfite to induce abiotic degradation of selected chlorinated hydrocarbons in groundwater. Aqueous microcosm tests were conducted with trichloroethylene (TCE), 1,1,1-trichloroethane (TCA), and carbon tetrachloride. Microcosm tests indicated abiotic dehalogenation of each of the compounds tested as evidenced by the production of the by-products 1,1-dichloroethylene, 1,1-dichloroethane, and chloroform, respectively. Parent compound losses of at least 20% relative to controls not containing sodium hydrosulfite were observed. An in situ field study involving injection of sodium hydrosulfite into an aquifer contaminated with TCE and 1,1,1-TCA was conducted at a Landfill site near Ottawa. The field test did not indicate significant degradation of TCE and 1,1,1-TCA in the aquifer. The results suggest that although an abiotic degradation process may be induced through the addition of sodium hydrosulfite, the process is likely too insignificant to have a measurable impact in an aquifer restoration application.