Biodegradation of Carbon Tetrachloride in Simulated Groundwater Flow Channels

摘要

Remediation feasibility studies were conducted in simulated groundwater flow channels for carbon tetrachloride (CT). CT was introduced at a concentration of about 2 mg/L (～13 μmoles/L) in three channels, two of them with alfalfa plants and the other with grass. Since no degradation products were found at the outlet after about 100 days, anaerobic conditions were created by adding one liter of 0.2% glucose solution in one channel (with alfalfa) and one liter of 0.1% emulsified soy oil methyl esters (SOME) to another channel (with alfalfa). The fraction removals of total chlorinated methanes in the outlet liquid were 94% in glucose fed channel and 92% in SOME fed channel. Supplements such as glucose, corn starch, cheese whey, and SOME stimulated the indigenous microbes to carry out the biodegradation of CT. In both glucose and SOME fed channels, the degradation continued several weeks after stopping the feeding of supplements. Most of the degradation process took place in the initial portion of the SOME fed channel, since SOME likely stayed near the inlet of the channel, due to sorption and retarded flow due to its low solubility; therefore, SOME should be added at multiple locations for effective bioreme-diation. No CT and degradation products were found in the headspace above the soil surface.