Use of zero-valent metals in in-situ remediation of contaminated ground water
- Univ. of Waterloo, Ontario (Canada)
- National Water Research Inst., Burlington, Ontario (Canada). Canada Centre for Inland Waters
Technologies based on the ability of metals to release electrons are being developed as possible methods for in-situ remediation of contaminated ground water. Laboratory tests have indicated considerable potential for removal of electroactive metals and for degradation of a wide range of halogenated aliphatic organic compounds. A laboratory column 15 cm in length was packed with 50 mass % each of iron fillings and quartz sand. After passage of 150 pore volumes of a solution containing 18 mg/L chromium, the concentration in the effluent remained below detection (0.05 mg/L). Under the highly reducing conditions in the column, the hexavalent chromium was precipitated as a highly insoluble chromium hydroxide/ferric hydroxide precipitate. It is postulated that the process could be effective for removal of other electroactive chemicals. In both batch and column tests, the addition of elemental iron was shown to be highly effective in enhancing degradation rates of chlorinated aliphatic compounds. The process appears to be reductive dechlorination, with iron serving as the source of electrons for the reduction process. Of 14 chlorinated methanes, ethanes, and ethenes that were tested, all (with the exception of dichloromethane) showed measurable rates of degradation. Normalizing the experimental results in 1 m{sup 2} of iron surface per ml of solution gave t{sub 50} values ranging from 0.013 to 20 hr. The normalized rates were 5 to 15 orders of magnitude greater than rates reported for natural abiotic degradation. Field studies are in progress to evaluate the use of metals as a fully passive in-situ method for groundwater remediation.
- OSTI ID:
- 398081
- Report Number(s):
- CONF-941124--; ISBN 0-935470-85-9
- Country of Publication:
- United States
- Language:
- English
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