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EFFECTIVE REMOVAL OF TCE IN A LABORATORY MODEL OF A PRB CONSTRUCTED WITH PLANT MULCH
Citation:
WILSON, J. T. EFFECTIVE REMOVAL OF TCE IN A LABORATORY MODEL OF A PRB CONSTRUCTED WITH PLANT MULCH. Presented at RTDF Permeable Reactive Barrier (PRB) Action Team Meeting, Charleston, SC, October 11 - 12, 2006.
Impact/Purpose:
To inform the public.
Description:
Ground water contaminated with TCE is commonly treated with a permeable 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. Concentrations of vinyl chloride were consistently less than 0.02 mM. Concentrations of cis-DCE, vinyl chloride, ethylene, ethane, and acetylene could account for 1% of the TCE that was removed. After 578 days of operation, three quarters of the TCE removal was associated with abiotic reactions with FeS that accumulated in the reactive matrix.