Field Application of In Situ Electrokinetic Remediation for As-, Cu-, and Pb-Contaminated Paddy Soil

An electrokinetic technique was used to remediate As-, Cu-, and Pb-contaminated paddy soil in a real field on a pilot scale. A hexagonal electrode placement with one anode at the center and six cathodes at the vertices of the hexagon was installed in the field. After operation for 4 weeks, the average removal of Pb was 64.9 % in the top layer (0-0.4 m), 81.2 % in the middle layer (0.4-0.8 m), and 66.9 % in the bottom layer (0.8-1.2 m). The removal of As was 28.2% in the top layer, 43.2 % in the middle layer, and 24.5 % in the bottom layer. The removal of Cu was 17.7 % in the middle layer and was not observed in the other layers. The relatively high removal of Pb might come from the more labile fraction of Pb in soil compared to As and Cu. However, the circulation of anolyte using an alkaline solution to enhance removal of As failed because the electrolyte leaked between the anode and surrounding soil. Effective circulation might enhance the performance of the electrokinetic process.