Volume 6, Issue 5 (May 2009)
Enhanced Electrokinetic Remediation of Mercury-Contaminated Tailing Dam Sediments
This study evaluates the use of different extracting solutions at the cathode during electrokinetic remediation to optimize the removal of mercury from gold mine tailing dam sediments in Iran. The total mercury concentration of the soil was 210 mg/kg and the duration of this experiment was 4 weeks. Experiments were conducted on the mine tailing recovered sediments with two voltage gradients (1.0 VDC/cm and 1.5 VDC/cm) to assess the effect of the voltage gradient when employing 0.1M Na-EDTA, 0.1M, and 0.4M KI solutions and distilled water. The test conducted on the soil showed that when the 0.1M and 0.4M KI concentrations were employed with a voltage gradient of 1.0 VDC/cm, approximately 50 % and 70 %, respectively, of the mercury was removed from the sediment. Also, it is understood that when the 0.1M and 0.4M KI concentrations were used with a voltage gradient of 1.5 VDC/cm, 65 % and 56 %, respectively, of the mercury was removed from the contaminated soil. The tests showed that mercury removal from sediment was less with distilled water and Na-EDTA as the extracting agents. The results also indicated that electrokinetic remediation for the concentration of 0.4M KI and with a voltage gradient of 1.0 VDC/cm was optimal for the approximately 70 % removal of the initial contamination. The reason for the remaining mercury in the sediment could be the presence of CaO, other metals, and organic compounds.