Remediation techniques for cadmium-contaminated dredged river sediments after land disposal

The remediation of heavy metal Cd contamination in municipal waste is one of the urgent environmental problems in China. To determine the best Cd pollution remediation technology, this paper investigates the applicability of various cadmium(Cd) remediation techniques in river treatment. These remediation methods are compared and analyzed based on the dredged river sediments after land disposal in a city in East China. Three remediation techniques of stabilization, soil leaching, and phytoremediation, are compared by analyzing the performance of the techniques for Cd-contaminated soil remediation. The experimental results show that the stabilization technique reduced the leaching rate of soil Cd from 33.3% to 14.3%, thus effectively reducing the biological toxicity of environmental Cd, but the total amount of Cd in soil did not decrease. Leaching soil with citric acid and oxalic acid achieved Cd removal rates of 90.1% and 92.4%, respectively. Compared with these two remediation techniques, phytoremediation was more efficient and easier to implement and had less secondary pollution but took a longer time(usually several years). In this study, these three remediation techniques were analyzed and discussed from technical, economic, and environmental safety perspectives by comprehensively considering the current status and future plans of the study site. Soil leaching was found to be the best technique for treating Cd contamination in dredged river sediments after land disposal.