Cincinnati, Ohio 14 October 2011 -- CL Solutions completed a bench-scale test of aerobic cometabolism of PCE and TCE in contaminated ground water. The purpose of the pilot study was to confirm applicability of aerobic cometabolism to a hazardous waste release site. Additional testing was undertaken to provide insight into the aerobic cometabolic pathway.
The pilot study included treated and untreated microcosms for comparison of contaminant levels, density of organisms producing relevant oxygenase, and potential intermediate organic acids. The treated microcosm received a single dosing of CL-Out organisms, dextrose as the cometabolic substrate, and nitrate.
The test results showed a decrease in PCE concentrations from 2,400 to 220 ug/L, TCE from 16 to 8.2 ug/L, DCE from 1,300 to 340 ug/L, and vinyl chloride from 3.9 to <1 ug/L. The density of oxygenase-producing cells was as much as 1,000 greater in the treated microcosm. Formic acid was not detected in either the untreated or treated microcosm. Trace levels of both di- and trichloroacetic acid were found in the treated, but not in the untreated microcosm.
The study results suggest that the aeobic cometabolic pathway for PCE and TCE degradation may be initiated by epoxidation and further oxidation to tri or dichloroacetic acid and final complete mineralization.