Treatment of Arsenic, Heavy Metals, and Acidity Using a Mixed ZVI-Compost PRB

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 was conducted at a former phosphate fertilizer manufacturing facility in Charleston, SC. The PRB is designed to remove heavy metals and arsenic from groundwater by promoting microbially mediated sulfate reduction and sulfide-mineral precipitation and arsenic and heavy metal 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