Comparison of Cr/Ni removal by electrokinetic (EK) and electrochemical geooxidation (ECGO) processes: Remediation performance and economic analysis in an in-situ system

Abstract

This study aimed to evaluate the in-situ remediation performance of Cr/Ni contaminated soil by the electrokinetic (EK) and the Electrochemical Geooxidation (ECGO) processes. The standard operating procedures, including Phase I-III (pre-engineering, remediation, and site restoration), in an in-situ EK/ECGO system were established. The effects of electrode configuration (Honeycomb and Square), potential gradient, and processing fluid on remediation performance were investigated. Results showed that the removal efficiencies of Ni and Cr were 27.3–39.3% and 6.1–30.1% in the honeycomb system, respectively, and were 46.2–48.5% and 3.1–12.2% in the square system, respectively. In particular, using the Fe/Al oxidation electrode hugely shifted the soil-metal bonds from stable to a less stable. Results showed that the cost of Phase II varied under different experimental conditions. In contrast, the cost of Phase I and III was independent experimental parameters. Cr and Ni removal cost was 0.34–1.01 USD g-1 and 0.23–0.36 USD g-1 in the honeycomb system, respectively, and was 1.41–5.58 USD g-1 and 0.50–0.71 USD g-1 in the square system, respectively. In terms of remediation efficiency and cost analysis, this study demonstrated that the overall performance in the honeycomb system was better than that in the square system.