ABSTRACT
This chapter investigates the biodegradability of 1,1,1-trichloroethane (TCA), 1,1-dichloroethane, and dichloromethane under anaerobic conditions. Also, the acclimation potential of a mixed anaerobic culture to the compounds was assessed. The metabolic fate of the chemicals under aerobic conditions have been studied widely, and degradation, if any, or persistence patterns established. Anaerobic studies with halogenated compounds have shown several of these compounds are biodegradable. Although there are disadvantages, such as long startup time and incomplete understanding of the microbiology involved, there is more evidence for biodegradation of chlorinated compounds in anaerobic systems than in aerobic systems. The list of halogenated species includes pesticides, plasticizers, plastics, solvents, and trihalomethanes. Continuous acclimation studies were performed with TCA, using the separately developed acetogenic and methanogenic cultures. Half-kill doses, determined from batch experiments, define a relative degree of toxicity for each of the compounds.
