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Treatment of Arsenic, Heavy Metals, and Acidity Using a Mixed ZVI-Compost PRB
Citation:
LUDWIG, R. D., D. J. Smyth, D. W. Blowes, L. E. Spink, R. T. WILKIN, D. G. JEWETT, AND C. J. Weisener. Treatment of Arsenic, Heavy Metals, and Acidity Using a Mixed ZVI-Compost PRB. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 43(6):1970-1976, (2009).
Impact/Purpose:
A 30-month performance evaluation of a pilot permeable reactive barrier (PRB)
Description:
A 30-month performance evaluation of a pilot permeable reactive barrier (PRB) consisting of a mixture of leaf compost, zero-valent iron (ZVI), limestone and pea gravel installed at a former phosphate fertilizer manufacturing facility was conducted. The PRB is designed to remove heavy metals and arsenic from groundwater by promoting both microbially-mediated sulfate reduction (i.e. sulfide precipitation) and arsenic sorption. Performance monitoring showed effective treatment of As, Pb, Cd, Zn, and Ni from concentrations as high as 206 mg L-1, 2.02 mg L-1, 0.324 mg L-1, 1060 mg L-1, and 2.12 mg L-1, respectively entering the PRB to average concentrations of < 0.03 mg L-1, < 0.003 mg L-1, < 0.001 mg L-1, < 0.23 mg L-1, and < 0.003 mg L-1, respectively within the PRB. Both As(III) and As(V) were effectively removed from solution with XANES core sample analysis indicating the presence of As(V) in oxygen-bound form and As(III) in both oxygen and sulfur-bound forms. Alkalinities measured as high as 650 mg L-1 as CaCO3 within the PRB indicated successful conversion of the high acidity influent ground water to a net acid consuming potential and 34S-SO4 isotopic enrichment observed within the PRB provided strong supporting evidence of sulfate reduction.
