Remediation and stimulation of selected chlorinated organic solvents in unsaturated soil by a specific enhanced electrokinetics

In this study, the remediation performance of a specific electrokinetic (EK) technology for removing chlorinated solvents including tetrachloroethylene (PCE), trichloroethylene (TCE), carbon tetrachloride and chloroform from unsaturated soils is investigated. The EK process is designed by a buffer solution of sodium acetate and a working-solution circulation system to neutralize the pH of the soil matrix. Results indicate that this EK process produces a roughly stable electro-osmotic (EO) flow rate (180 mL/day), pH (around 6.0), and current density (0.26–0.27 mA/cm2). All selected chlorinated organic compounds can be effectively removed from the soil with removal efficiency ranging from 85 to 98% after 2 weeks of treatment. The mobility of chlorinated solvents in soils increases with the increase of its water solubility, i.e., chloroform > carbon tetrachloride > TCE > PCE. The transport simulation by a mathematical diffusion–advection–sorption (DAS) model with the linear sorption isotherm is approximately feasible to describe the removal kinetics of chlorinated solvents in unsaturated soils under the enhanced EK conditions by tuning the parameter of mechanical dispersion.