Generation And Impact Of Focusing Band On The Electrokinetic Remediation Of Chromium-contaminated Soil

In recent years, the rapid development of China’s industries leads to serious soilcontamination issue caused by heavy metals. As the levels of heavy metals accumulatedin soils reach to a certain extent, it will cause harm to the water, soil and floraenvironment system, and endanger human health. Heavy-metal contamination featuresinvisibility, irreversibility and long-term effect and the relevant studies are still hot spotsover the world. Electrokinetic remediation is a new in-situ remediation technology,characterized by saving time, low energy and reagent consumption, easy to installationand operation, especially suitable to the soils of low permeability.Soil conductance heterogeneity of contaminated sites is prevalent, and the highconductance bands could cause focusing bands in the soils during electrokineticremediation (EKR). This paper added KNO3with the formation of high conductivityinvestigates the generation and moving patterns of the focusing bands and its impacts onthe efficiency of EKR, using the Cr-contaminated kaolin-gypsum soil. We found that:(1) The high conductance band in soils can cause focusing phenomenon and thehigher the conductance the more significant the focusing phenomenon.(2) The focusing band can migrate laterally into the surrounding clean soil causingpollution diffusion to some extent.(3) The location of focusing bands could significantly impact the electrokineticremediation duration and energy efficiency. The long distance between the focusingband and the anode could prolong the duration of EKR resulting in higher energyconsumption.