Cometabolic and biotic conversions were observed to be significant mechanisms for the transformation of chlorinated ethanes by the methanogenic consortium in a UASB reactor by van Eekert et al. (1999). The effect of 1,1,2,2 tetrachloroethane (TCE) on a UASB reactor fed with a synthetic wastewater was determined by Navarrete et al. (1999). The results showed that the UASB had
the potential to treat industrial wastewaters containing TCE.