TRANSFORMATIONS OF 1,1,2,2-TETRACHLOROETHANE UNDER METHANOGENIC CONDITIONS

Abiotic and biotic transformations of 1,1,2,2-tetrachloroethane (TeCA) under methanogenic conditions were studied. TeCA degradation started without lag with municipal digester sludge. 1,1,2-Trichloroethane (1,1 ,2-TCA), trans-1,2-dichloroethene (to CE), and cis-1,2-dichloroethene (cDCE) were products of biotic transformation, while trichloroethene ( TCE) resulted from abiotic degradation. TCE was further transformed to cDCE, vinyl chloride (VC), and ethene. Ethene, VC, and tDCE were the persistent products of TeCA transformations. With the same municipal d igester sludge culture, 1,I,P-TCA was removed and converted to 1,2-dic hloroethane (1,2-DCA) and VC. 1,2-DCA partially degraded, resulting in chloroethane and ethene formation. Reductive dechlorination, dichloro elimination, and dehydrochlorination simultaneously took place during the degradation of TeCA. Dichloroelimination and dehydrochlorination p layed important roles in the removal of TeCA and 1,1,2-TCA under metha nogenic conditions.