Soil Remediation For Cadmium Contaminated Soil By Washing And Stabilization Technology

Cadmium pollution in soil system is mainly due to human activities, which will reduce the yield and quality of crops, and enter the body through the food chain and harm human health. At present, soil cadmium pollution has caused widespread concern.This paper studied the leaching technology and stabilization technique to repair the cadmium contaminated soil via lab experiment.The purpose of soil washing is to select the appropriate leaching agent and research the optional operating conditions.The main content of stabilization is to determine the adding proportion of stabilizers.The main conclusions are as follows:(1)Compared EDTA, citric acid, tartaric acid, oxalic acid, hydrochloric acid and deionized water effect on leaching of soil samples selected EDTA, tartaric acid and hydrochloric acid as the eluent better follow-up experiment, to explore better leaching conditions. EDTA optimum leaching conditions are as follows:the concentration of 0.lmol/L, pH value of 3, leaching time was 8h, cadmium removal was 71.04%. Best tartaric acid leaching conditions as follows:the concentration of 0.05mol/L, leaching time was 6h, cadmium removal was 71.87%. Best hydrochloric acid leaching conditions were:concentration of 0.05mol/L, leaching time was 4h, cadmium removal was 79.64%. After rinsing twice better than the leaching one time, the better soil to liquid ratio as follows:EDTA and HC1 is 1:10, tartaric acid 1:15.(2) Selected lime, potassium dihydrogen phosphate, bentonite and fly ash as the stabilizer stabilization techniques. When lime is added in an amount of 1% potassium dihydrogen phosphate content is 10% fly ash adding 5%, the leaching solution of cadmium concentrations of 0.555mg/L,0.994mg/L,0.028 mg/L, were lower than the "hazardous Waste Identification standard extraction procedure toxicity" (GB 5085.3-2007) leaching standard value toxicity lmg/L. At this point the pH of the soil was 8.37,6.06,9.60. When bentonite dosage 20%, the concentration of cadmium leaching solution was 1.284mg/L, which is still greater than the national standard leaching toxicity criteria values. Thus, lime, potassium dihydrogen phosphate and fly ash can be used as cadmium contaminated soil stabilizer.(3) On the basis of a single stabilizer repair on the design of the composite repair experimental results showed that:the effect of composite restorations to repair a little better than a single effect. When the drug combination was 0.5%+5% potassium dihydrogen phosphate of lime, fly ash 0.5%+5% potassium dihydrogen phosphate, leaching concentration was 0.942mg/L and 0.913mg/L better than the single repair effect. When fly ash and lime dosage of 1%, the leaching concentrations were up to standard. Adding potassium dihydrogen phosphate concentration is 10%, the leaching concentration also comply with the relevant standards.0.5% ash+ 5%KH2PO4,0.5%CaO+5%KH2PO4 ideal for repairing combination...