New approaches to remediate heavy metals containing polluted soil via improved PCPSS

Abstract

Soil pollution with heavy metals is worldwide problem. Recently, a new process for removing heavy metals, known as the perforated cathode pipe soil electrokinetic remediation (SEKR) system (PCPSS), was proposed and tested with Pb2+ and Zn2+. In this study, the PCPSS design was improved by changing electrode configuration and by incorporating a drainage system to prevent the formation of an unsaturated zone and to improve the distribution pH throughout the contaminated soil. Our five newly-developed designs were compared with the typical PCPSS design. In our tests, we used pure clay (kaolinite) polluted with Cu2+ at an initial concentration of 200 mg kg−1. The best design from our pilot study was then compared with the typical PCPSS design using natural, clayey soil polluted with Zn2+, Cd2+, Co2+, Mn2+, Pb2+, Ni2+, Sr2+ (total strontium), and Cu2+. Our results showed that a vertical anode/perforated cathode pipe SEKR system (VA-PCPSS) is the best alternative to the typical PCPSS design because neither a pH jumping zone nor an unsaturated zone formed in the soil. VA-PCPSS is suitable for removing Zn2+, Cd2+, Co2+, and Mn2+; however, little Pb2+, Ni2+, Sr2+, and Cu2+ were removed.