Aerobic Degradation of Trichloroethylene at High Concentration by a Methane-Utilizing Mixed Culture

Abstract

A number of soil and activated sludge samples were screened as to their ability to degrade trichloroethylene (TCE). A mixed culture involving a soil sample was selected as the most active one. After several subcultures, this mixed culture was found to contain a type II methanotroph, which appeared to be responsible for the TCE degradation. The mixed culture required methane and oxygen for TCE degradation, but methanol, ethanol, ethane, formic acid, acetic acid or glucose could not be substituted for methane. TCE at the high concentration of lOppm was degraded to a level corresponding to 40% of the initial concentration in 10 days. The mixed culture was also able to degrade three other chlorinated alkenes, cis- and trans-1, 2-dichloroethylene and vinyl chloride, and four chlorinated alkanes, 1, 1, 2, 2-tetrachloroethane, 1, 1, 2-trichloroethane, 1, 2-dichloroethane and chloroform, but not tetrachloroethylene, 1, 1, 1-trichloroethane or carbon tetrachloride.