LAUSR

Abstract Soil flushing solution (SFS) from Cr(VI)-contaminated soil flushing remediation is a kind of non-industry-sourcing Cr(VI)-containing wastewater. The requirement of on-site treatment of SFS proposes high level requirements for the operational simplicity and transportability. This paper exhibits an on-site application-oriented continuous electrocoagulation (EC) system for SFS treatment. By a novel design, the products of a series of electrochemical, redox and precipitation reactions were used to create an acidic region for Cr(VI) reduction by Fe 2+ and a basic region for Cr x Fe y (OH) z precipitation. The concentrations of Cr(VI), total Cr and total suspended solids in the treated SFS were less than 0.03 mg·L −1 , 0.16 mg·L −1 and 39 mg·L −1 respectively, complying with the typical environmental legislation for discharges. Experiments of stirring intensity effect shows that stirring is necessary to decrease Cr(VI)/TCr in sediments. Comparison of desorption kinetics between treated SFS and tap water shows that the Cr(VI) desorption efficiency with treated SFS is slightly higher than with fresh tap water, meeting the requirement for the reuse of SFS. Compared with other continuous EC systems, this continuous EC system eliminates the requirement of pH monitoring and adjusting and improves operational simplicity and transportability.