Column Experiment for the Removal of Cadmium, Copper, Lead and Zinc from Artificially Contaminated Soil using EDTA, Rhamnolipids, and Soapnut

Abstract

Environmental contamination caused by high contents of toxic metals in the soil is a global concern. Soil washing using chelating agents and saponin can enhance metal removal from contaminated soils through the formation of soluble metal complexes, mobilization, and extraction with the washing solutions. Column experiments were conducted in this study to assess the feasibility of using a chelate (EDTA), a saponin (soapnut) and microbial (rhamnolipid) cleaning agents to enhance the removal of Cd, Cu, Pb and Zn from sandy loam contaminated soils. The cumulative removal of Cd after 10 pore volumes were 74.05 for EDTA, 63.08 for rhamnolipids, and 69.07 for soapnut. The cumulative removals of Cu after washing with 10 pore volumes were 64.72% for soapnut, 61.58% for rhamnolipids and 61.95% for EDTA. Also, the cumulative removals of Pb were 62% for soapnut, 59.65% for rhamnolipids and 59.95% for EDTA after washing with 10 pore volumes. The cumulative removals of Zn after washing with 10 pore volumes were 68.54% for soapnut, 62.65% for rhamnolipids and 66.08% for EDTA. The performance of these experiments demonstrates that the application of these cleaning agents in in-situ soil remediation can be effective alternative to ex-situ remediation.