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TRICHLOROETHYLENE REMOVAL FROM GROUNDWATER IN FLOW-THROUGH COLUMNS SIMULATING A PERMEABLE REACTIVE BARRIER CONSTRUCTED WITH PLANT MULCH
Citation:
SHEN, H. AND J. T. WILSON. TRICHLOROETHYLENE REMOVAL FROM GROUNDWATER IN FLOW-THROUGH COLUMNS SIMULATING A PERMEABLE REACTIVE BARRIER CONSTRUCTED WITH PLANT MULCH. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 41(11):4077-4083, (2007).
Description:
Ground water contaminated with TCE is commonly treated with a passive reactive barrier (PRB) constructed with zero-valence iron. The cost of iron as the reactive matrix has driven a search for less costly alternatives, and composted plant mulch has been used as an alternative reactive matrix at several sites. A column study was conducted that simulated conditions in a PRB at Altus Air Force Base, Oklahoma. The reactive matrix was 50% (v/v) shredded tree mulch, 10% cotton gin trash, and 40% sand. The mean residence time of ground water in the columns was 17 days. TCE was supplied at concentrations near 20 mM. Concentrations of TCE in the column effluents varied from 1% to 0.1% of the column influents. Sorption was not an important removal mechanism; the retardation factor for TCE was only 2.6. Concentrations of cis-DCE, vinyl chloride, ethylene, ethane, and acetylene could account for l% of the TCE that was removed; however, up to 7% of 13C added as [13C] TCE in the column influents was recovered as 13C in carbon dioxide. After 578 days of operation, three quarters of the TCE removal was associated with abiotic reactions with FeS that accumulated in the reactive matrix.