Removal of Lead and Copper from Contaminated Mixed Clay Soils Using Pulsed Electrokinetics

High energy consumption is one of the major setbacks of electrokinetic remediation (EKR) of contaminated soils. This study investigated the effect of bentonite/clay ratio, pulse duty cycle and voltage gradient on pulsed electrokinetic remediation (PEKR) of Cu and Pb contaminated soil. Maximum removal efficiencies of 17.81% and 62.41% were achieved for both Pb and Cu, respectively. Adsorption, as well as Precipitation, were found to contribute to the lower removal efficiencies due to high soil pH, soil properties amongst others. RSM Models with good predictability of behavior of the studied parameters were generated. The p-values for the individual models were found to be less than 0.05, implying the statistical significance of the models. An increase in the pulse duty cycle was found to increase the removal efficiencies of both Cu and Pb. An increase in voltage gradient increased the Pb removal efficiency but conversely decreased Cu removal efficiency. Also, bentonite ratio was found to decrease the Cu removal efficiency but had insignificant effect on Pb removal efficiency. The total energy consumption over the 3 weeks treatment time for maximum Cu and Pb removal was found to be 146.65 kwh/m³ and 1151.58 kwh/m³, which are both lower than 2068 kwh/m³ obtainable in the traditional EKR. This study shows that more reduction in energy consumption is feasible through careful selection of experimental conditions and factors (pulse duty cycle and voltage gradient).