Kinetics of tetrachloroethylene transformation investigated up to solubility by a dechlorinating microbial assemblage.

Abstract

In order to investigate the applicability of bioremediation of tetrachloroethylene (PCE) in source zones, batch experiments were carried out using a dechlorinating microbial assemblage. Initial aqueous PCE concentrations were in the range of 0.09 to 0.8mM and up to the solubility limit ( 1.2mM) with the presence of PCE as a separate phase. Although recent publications suggest that PCE could be dechlorinated up to saturation concentrations by mixed cultures, the dechlorinating microbial assemblage tested in this study was only able to dechlorinate PCE up to approximately 0.5 mM. No dechlorination was found at higher initial PCE concentrations. Dechlorination of PCE was described by a biokinetic model with the Michaelis-Menten equation including self inhibition with a maximum degradation rate of 80 mol PCE l����1 day����1, a half saturation constant of 0.33mM and a PCE inhibition constant of 0.5 mM. In the literature, microbial capabilities to transform PCE are found to be higher. However, these reported values on dechlorination of saturated PCE concentrations by laboratory cultures might have resulted in adaptation to higher PCE concentrations.