A comprehensive laboratory investigation was performed to characterize the geochemistry of the soils contaminated with heavy metals and to enhance the heavy metal removal. Two types of soils were used in this study; kaolin, a typical low buffering soil, and glacial till, a typical high buffering soil.; Based on the geochemical characterization experiments, it was observed that, precipitation of nickel and cadmium in the cathode region and adsorption of Cr(VI) near anode were found to hinder the removal of heavy metals in kaolin. Acetic acid, EDTA, and sequentially enhanced electrokinetic remediation process (SQEEK) were used to enhance the migration of chromium, nickel and cadmium in kaolin. In SQEEK tests, various purging solutions were introduced into the soil at different stages of the experiment. EDTA performed better for the removal of chromium and acetic acid was better in removing nickel and cadmium. For the removal of all the three contaminants, chromium, nickel and cadmium, SQEEK performed better.; In high buffering soils, precipitation of nickel and cadmium was found to be the major fixation mechanism. EDTA, acetic acid, citric acid and sulfuric acid were used to enhance the migration of the heavy metals. In another test with EDTA, the conductivity of medium was increased by adding NaCl from the anode reservoir. This test yielded highest removal of chromium as compared to the other purging solutions. Nickel and cadmium migration towards the anode was very efficient in the same test, however, all the nickel and cadmium was accumulated near anode region. Overall, the results showed the feasibility of heavy metal removal from high buffering soil, such as glacial till, however, further study is needed to determine the effective purging solution remove nickel and cadmium from the anode region.
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