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TREATMENT OF HEAVY METALS USING AN ORGANIC SULFATE REDUCING PRB
Citation:
Ludwig*, R, K. Mountjoy, R. McGregor, AND D. W. Blowes. TREATMENT OF HEAVY METALS USING AN ORGANIC SULFATE REDUCING PRB. Second International Conf on Remediation of Chlorinated and Recalcitrant Compounds, Monterey, CA, May 22-25, 2000.
Description:
A mpilot-scale permeable reactive wall consisting of a leaf-rich compost-pea gravel mixture was installed at a site in the Vancouver area, Canada to evaluate its potential use for treatment of a large dissolved heavy metal plume. The compost based permeable reactive wall promotes microbially-mediated sulfate reducing conditions such atht dissolved metals are precipitated out as metal sulfides. The pilot-scale wall, measuring 10 m in length, 5.9 m in depth, and 2-2.5 m in width, has demonstrated good effectiveness in removing dissolved copper, cadmium, zinc, and nickel from ground water at the site over a 21-month period since installation. Performance has been particularly strong within the lower half of the wall where tidal influences are more limited and sulfate-reducing conditions are more easily maintained. Dissolved copper concentrations decrease from concentrations of over 4500 ppb in the influent ground water to less than 10 ppb, within the lower half of the wall. Zinc, cadmium, and nickel concentrtions decrease from average concentrations of over 2300 ppb, 15 ppb, and 115 ppb, respectively to concentrations of less than 30 ppb, 0.2 ppb, and 10 ppb, respectively within the lower half of the wall. The activity of sulfate reducing bacteria is evidenced by a significant increase in sulfide concentrations within the wall.