Pilot Scale Ex-Situ Electrokinetic Remediation of Arsenic-Contaminated Soil

In this study, the effectiveness of ex situ electrokinetic remediation (EKR) in treating actual As-contaminated soil was evaluated at a pilot scale (1 m [W] × 1 m [L] × 1.5 m [H]). Ethylenediamine tetraacetic acid (EDTA) and sodium hydroxide as the catholyte and anolyte, respectively, were circulated to enhance the desorption of As. Two types of soil were collected from a real contaminated agricultural area: silty loam from a rice paddy and sandy clay loam from dry land. An average of 78% of the As was removed from the two types of soil after 8 weeks, and the residual As concentration met the level set by Korean legal regulations. The average removal rates were 1.06 and 1.55 mg/kg/day, respectively, for the paddy and dry field soil samples. In addition, fractionation analysis showed that most other fractions and even a large portion of the residual fraction were removed after EKR. The ex situ application provided electrolyte more uniformly to the entire soil sample; therefore, there was no significant variation in As removal depending on the depth of the soil. These results indicated that ex situ EKR is an effective technique for the remediation of As-contaminated sites.