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Contributions of Fe Minerals to Abiotic Dechlorination
Citation:
WILSON, J. T. AND M. Ferrey. Contributions of Fe Minerals to Abiotic Dechlorination. Presented at University Consortium for Field-Focused Groundwater Contamination Research 2008 Focus Meeting. Natural Attenuation Tools for Quantification and Implications, Denver, CO, October 23 - 24, 2008.
Impact/Purpose:
The purpose is to observe the rates of TCE degradation by FeS that is produced by biological sulfate reduction
Description:
Most applications of enhanced in situ bioremediation are based on biological reductive dechlorination. Anaerobic metabolism can also produce reactive minerals that allow for in situ biogeochemical transformation of chlorinated organic contaminants such as PCE, TCE, and cis-DCE. Sulfate reduction can produce iron sulfides including FeS and FeS2. Magnetite (FeO.Fe2O3) can be produced in situ by iron reduction. FeS can degrade chlorinated ethylenes to acetylene under anaerobic conditions. Rates of TCE degradation by FeS that is chemically synthesized are near 0.067 per day at pH 7.0 in presence of 1.0 mole FeS in contact with 1.0 liter of water (M*). Rates of TCE degradation by FeS that is produced by biological sulfate reduction vary from 2.3 and 0.53 per day per M*. Magnetic susceptibility can serve as a very inexpensive screening test for the presence of magnetite. A magnetic susceptibility in the range of 0.1 to 1.0 X10-6 m3 kg-1 can sustain first order rates of removal near 0.3 per year.