Comparative efficiency of microbial systems for destroying carbon tetrachloride contamination in Hanford groundwater

摘要

Past waste disposal practices at the US Department of Energy's (DOE) Hanford site have resulted in carbon tetrachloride (CCl(sub 4)) and nitrate contamination in the groundwater. In situ bioremediation is currently being investigated as a cost effective means to destroy these groundwater contaminants. The cost effectiveness of bioremediation is significantly influenced by the nutrient amendments required to sustain the contaminant destruction reactions. This is particularly important for bioremediation of CCl(sub 4) because its biodestruction is the result of a cometabolic process. Nutrient amendments are also important in controlling the growth characteristics of the bacteria to prevent biofouling. Current and previous research has focused on determining the reaction kinetics and microbial processes for CCl(sub 4) destruction using acetate as the electron donor for indigenous microbes. This study was conducted to determine if electron donors other than acetate may be more cost effective, or may provide a better means of process control, for in situ bioremediation of CCl(sub 4) contamination. Three alternative electron donors, glycerol, methanol, and ethanol, were screened for their ability to stimulate CCl(sub 4) destruction. Detailed reaction kinetic experiments using an indigenous microbial consortium with these substrates and with acetate were conducted to determine the efficiency of each in destroying CCl(sub 4).