Biostimulation of trichloroethylene degradation in contaminated aquifers

This study investigate the relative efficacy of selected oxygenase inducers to stimulate trichloroethylene (TCE) biodegradation at psychrophilic temperatures (12°C) encountered in shallow aquifers of the northern United States or mesophilic room temperature (24°C) typical of most laboratory experiments. Experiments were done in flask and batch-exchange column microcosms comparing methane and ammonium as biostimlunts.  In flask or column microcosms incubated at mesophilic temperatures, lag times preceding methanotrophic TCE biodegradation were shorter than those of the ammonia-oxidizers and methanotrophs in both microcosm systems was similar in terms of [¹⁴C]TCE mineralization levels, TCE biodegradation rates, and TCE biodegradation efficiencies (rates normalized to microbial activity).  Incubation at psychrophilic temperatures increased the lag periods and decreased the biodegradation rates and efficiencies for ammonia-oxidizers and methanotrophs in both microcosm types.  However, in both the flask and column experiments psychrophilic ammonia-oxidizers were consistently more effective TCE degraders than were psychrophilic methanotrophs.  These experiments demonstrated that in situ bioremediation of TCE is feasible at the psychrophilic temperatures common in surficial aquifers in the northern United States, and that for such applications biostimulation of ammonia-oxidizers could be more effective than previously believed.