Electroosmosis and pore pressure development characteristics in lead contaminated soil during electrokinetic remediation

Abstract

Physical and chemical reactions occur during the electrokinetic treatment. When an electric current was applied to soil for some duration, fluid transport phenomena occurred in the soil-water system and the characteristics of soil-water interface varied according to the pH levels due to electrolysis. In addition, reactions occurring within the electrokinetic system are changed according to the inter-reactions of the clay property and electrohydraulic conductivity. In this study, the hydraulic phenomena and the variations of its properties were investigated during the electrokinetic remediation treatment of lead contaminated soil. To do this, laboratory testing on the lead-contaminated soil was performed and the pH distribution, electroosmotic flow, and pore pressure were measured. The zeta potential, with respect to contaminant concentration and pH level, was also investigated through the analysis of the physicochemical relationships. The flow velocity of the electroosmosis was found to be sensitive to the chemical characteristics of the clay and contaminant concentration. As the concentration of lead increased, the flow rate decreased and negative pore pressure occurrs near the cathode due to the differences in flow rates between the electrodes. This negative pore water pressure was proportionate to the flow rate, i.e., a larger flow rate developed a larger negative pore water pressure.