Improvement in electrokinetic remediation of Pb-contaminated soil near lead acid battery factory

To improve the conventional electrokinetic remediation of Pb-contaminated soil, the Pb-contaminated soil near a lead acid battery factory in the Pearl River Delta region of China was electrokinetically remedied with polarity exchange technique. The variations in Pb removal efficiency and the soil pH value with the treatment time and the exchange polarity interval were determined. It is found that the removal efficiency of Pb reaches a maximum of 87.7% when the voltage gradient is 1 V/cm and the exchange polarity interval is 48 h. This value is far higher than that obtained with conventional electrokinetic remediation (61.8%). Additionally, the “focusing effect” which appears in the conventional electrokinetic remediation can be avoided, and thus additional chemicals are not needed for the polarity exchange technique. The mechanism of Pb electromigration behavior in soil during the treatment with the polarity exchange technique was described.