1,1,2,2-tetrachloroethane aerobic cometabolic biodegradation by propane- and methane-utilizing consortia in slurry bioreactors

This slurry microcosm study was aimed at investigating the process of 1,1,2,2-tetrachloroethane (TeCA) aerobic cometabolic biodegradation by the indigenous biomasses of 5 aquifers, and the efficacy of different microbial inocula in enhancing the TeCA degradation process. Methane and propane were tested as growth substrates. 4 of the 5 tested indigenous biomasses were capable to start growing on propane and degrading TeCA within acceptable lag-times, indicating that aerobic cometabolism represents a potentially effective approach for the bioremediation of TeCA-contaminated aquifers. The introduction of the tested microbial inocula led to a rapid onset of TeCA aerobic biodegradation in the aquifer material that had proved unable to deplete TeCA in the absence of inoculation. In the microcosms containing the other 4 aquifer materials, the inocula induced marked decreases of the lag-time for the onset of the cometabolic process. Besides, in all the experimental conditions the TeCA biodegradation rates obtained in the inoculated tests were equal or higher than the corresponding rates obtained in the absence of inoculation. This study represents to the best of our knowledge the first investigation entirely dedicated to aerobic TeCA cometabolism.