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, zerovalent 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 <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 X-ray absorption near edge structure (XANES) analysis of core samples indicating the presence of As(V) in oxygen-bound form and As(III) in both oxygen- and sulfur-bound forms. XANES solid phase sulfur analysis indicated decreases in the peak amplitude of intermediate oxidized sulfur species and sulfate components with increasing distance and depth within the PRB.
National Risk Management Research Laboratory, Office of Research and Development, U.S. EPA, Ada, Oklahoma 74820, USA. ludwig.ralph@epa.gov
Ralph D
RD
Ludwig
David J A
DJ
Smyth
David W
DW
Blowes
Laura E
LE
Spink
Richard T
RT
Wilkin
David G
DG
Jewett
Christopher J
CJ
Weisener
D001151:Arsenic / Q000737:chemistry*; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D019216:Metals, Heavy / Q000737:chemistry*; D010865:Pilot Projects; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000737:chemistry*
D007220:Industrial Waste; D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D001151:Arsenic