The application of in situ permeable reactive (zero-valent iron) barrier technology for the remediation of chromate-contaminated groundwater: a field test

A small-scale field test was initiated in September 1994 to evaluate the in situ remediation of groundwater contaminated with chromate using a permeable reactive barrier composed of a mixture of zero-valent Fe, sand and aquifer sediment. The site used was an old chrome-plating facility located on a U.S. Coast Guard air base near Elizabeth City, North Carolina. Dissolved chromate concentrations were reduced to less than 0.01 mg/L via reduction from Cr(VI) to Cr(III) as a result of the corrosion of the Fe. As the Fe corrodes, pH increases, oxidation-reduction potential declines, dissolved oxygen is consumed, and Fe(II) is generated. Mineral phases formed as a result of the Fe corrosion include ferrous sulfides and various Fe oxides, hydroxides, and oxyhydroxides.