Removal of inorganic contaminants in soil by electrokinetic remediation technologies: A review

The soil contaminated by inorganic contaminants including heavy metals, radioactive elements and salts has been posing risks for human health and ecological environment, which has been widely paid attention in recent years. The electrokinetic remediation (EKR) technology is recognized as the most potential separation technology, which is commonly used to clean sites that are contaminated with organic and inorganic contaminants. It is the most suitable remediation technology for low permeability porous matrices. The main transport mechanism of pollutants in EKR include electromigration, electroosmosis and electrophoresis, coupled with electrolysis and geochemical reactions. Although arduous endeavors have been carried out to build optimal operating conditions and reveal the mechanism of EKR process, a systematic theoretical foundation hasn’t been sorted yet. A comprehensive review on electrokinetic remediation of inorganic contaminants in soil is given in this study, and a more systematic theoretical foundation is sorted out according to the latest theoretical achievements. This theoretical system mainly focuses on the scientific and practical aspects of the application of EKR technology in soil remediation, by which we try to dig into the core of this technology. It contains key motive power of electric phenomena, side effects, energy consumption and supply, and removal of heavy metals, radioactive elements and salts in soil during EKR. In addition, correlations between dehydration, crystallization effect, focusing effect and thermal effect are disclosed; optimal operating conditions for the removal of heavy metals by EKR and EKR coupled with PRB are discussed and sorted out. Also discussed herein is the relationship between energy allocation and energy saving. According to the related findings, some potential improvements are also proposed.