In situ field scale electrokinetic remediation of multi-metals contaminated paddy soil: Influence of electrode configuration

We evaluated the influence of electrode configuration on in situ electrokinetic remediation of As-, Cu-, and Pb-contaminated soil in a pilot-scale field application. Dense electrode configurations resulted in high current under a constant voltage gradient, the high current raised soil temperature, and it caused unnecessary electrical energy consumption. Additionally, temperature increase in soil transported pore water from bottom to top layer, which accumulated contaminants in the top soil layer because the mobilized contaminants was co-transported by the water flow. On the other hand, the groundwater flow, gravitational force, and electro-osmotic flow were combined together and affected complexly the transport of mobilized contaminants. Sequential extraction showed that electrokinetic treatment increased the residual fraction of As, the fraction of Cu bound to organic matter, and the fraction of Pb bound to organic matter and residual portion. This result implies that the groundwater flow and soil temperature should be monitored during the remediation and the configuration should be considered to minimized unnecessary transport of contaminants.