Remediation of heavy metals contaminated soil by enhanced electrokinetic technology: A review

Abstract

Electrokinetic (EK) remediation is based on EK concepts that can successfully remove heavy metals (HMs) from soil. Traditional EK remediation is limited by focusing effect, electrode polarization, soil acidification/alkalization, and other variables. Thus, many enhanced technologies have been studied to improve EK remediation. This review systematically summarizes the progress of research on enhanced technologies for EK remediation by optimizing EK system key components (ion exchange membranes, electrodes, electrolytes, and power supply), and the advantages and disadvantages of each technology were also compared. Specifically, appropriate electrode materials with high conductivity and EK activity positively influence HMs removal during the EK process. The arrangement of electrode matrix, electrode exchange, and electrode approaching significantly impact HMs removal efficiency and energy consumption cost. Additionally, selecting suitable electrolytes can enhance the dissolution of soil HMs to improve the remediation rate. AC is not commonly used for HMs removal but can effectively combine with phytoremediation techniques. Furthermore, we summarize the application of EK remediation on a field scale and the effects of EK remediation on soil resilience. Finally, we propose the following research prospects: (1) the development of enhanced technology should be based on practical considerations for application on a field scale, (2) soil resilience should be an important indicator for the evaluation of EK remediation, and (3) variation of HMs fraction before and after EK remediation need to be concerned.