Abstract:Stepwise continuous precipitation method was applied to recover and purify the wasted oxalic acid (OA) solution from washing process of high concentration of Sb and As soil. The results show that OA recovery rate from wasted washing solution is 35.54% when the pH value is controlled at 1.4, and the washing efficiencies of recycled OA solution on Sb and As contaminated soil is 38.39% and 55.54%, respectively. When the pH value rises to 8—9, the removal rate of Sb and As in the waste solution is more than 99%. At the same time, the leaching toxicity of heavy metals such as Cd, As and Sb in sediment produced during the process is all lower than the relevant concentrations in the “Identification Standards for Hazardous Wastes-Identification for Extraction Toxicity” (GB 5085.3—2007). Therefore, the stepwise continuous precipitation method can recover OA from wasted washing solution, and reduce the cost and environmental risks of soil washing technology. Thus, this study provides a theoretical reference for the recovery and purification of wasted soil washing solution.