Characterization and Optimization of Dual Anaerobic/Aerobic Biofilm Process

The purpose of this Phase I STTR effort was to develop and characterize a dual anaerobic/aerobic biofilm process that promotes anaerobic reductive dehalogenation and aerobic cometabolic biodegradation, simultaneously, in a single biological reactor. The project focused on establishing the proof-of-concept for the simultaneous anaerobic dechlorination of tetrachloroethylene (PCE) and cometabolic oxidation of trichloroethylene (TCE) within a single laboratory-scale fluidized bed bioreactor (FBR) operated under bulk aerobic conditions . Concomitant BTEX (benzene, toluene, ethylbenzene, and xylenes) removal was also demonstrated. The bioreactor was inoculated with anaerobic sludge and a culture of the bacterium Burkholderia cepacia G4, which degrades TCE in the presence of Toluene. Over the length of the project, approximately 90 and 80 percent of the PCE and TCE added to the system was degraded, respectively. BTEX removal efficiencies were consistently greater than 99 percent. No dichloroethene or vinyl chloride was detected in liquid or vapor effluent samples. The bioreactor contained anaerobes that could dechlorinate PCE during serum bottle experiments. The anaerobes could use methanol or hydrogen, but not toluene, as electron donors to reduce PCE. Biomass removed from the bioreactor was also capable of degrading TCE in serum bottles at rates comparable to those observed during operation of ENVIROGEN's field-pilot TCE bioreactors.