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 (tDCE), 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 digester
sludge culture, 1,1,2-TCA was removed and converted to 1,2-dichloroethane (1,2-DCA) and VC. 1,2-DCA partially degraded, resulting in chloroethane
and ethene formation. Reductive dechlorination,
dichloroelimination, and dehydrochlorination simultaneously took place during the degradation of TeCA.
Dichloroelimination and dehydrochlorination played
important roles in the removal of TeCA and 1,1,2-TCA
under methanogenic conditions.