Study On The Remediation From Copper And Lead Polluted Soil By Electrokinetic Combining With Washing

The heavy metal pollution have been getting more and more serious recent years. The pollution of mining areas and arable lands is a big threat to local people. There are many procedures to remediate the heavy metal polluted soil. Electrokinetic remediation is one of these remediation procedures and is known for its high efficiency and low cost. It is particularly suited for water solubility pollutant in soil with low permeability and high density. Moreover, pH value has a high influence on the removal rate of electrokinetic remediation. Alkaline environment in soil is near cathode zone and it is a big hinder to the remediation. Because of it, metal ions precipitate too early to get anode zone, and removal rate become quite low. So it is necessary to optimize the electrokinetic remediation.In this study, electrokinetic remediation is used to investigate the removal and transformation of Pb and Cu in artificial polluted soil. The reactor has three parts and made by polymethyl methacrylate. Exploring the influencing factor in electrokinetic remediation, and combining soil washing with it. Meanwhile, metal content,metal speciation and soil properties are analyzed before and after the remediation to check the influence of the remediation on the soil. The main contents include:(1) the traditional electrokinetic remediation;(2) soil washing remediation;(3) remediation of electrokinetic combining with washing.By far, the conclusions are as follows:(1) Remediation voltage should below the hydrogen evolution potential, and remediation time should consider both efficiency and power consumption. Acidified soil had the high removal date as 35.90%、25.29% with 5days and 1.5 V/cm. However, due to the soil buffering and the influence of hydroxide ion, the removal rate was pretty low.(2) Citric acid was better in leaching for heavy metal extraction and the concentration could reach 32845.10 mg/L and 19742.50 mg/L. The stability of Pb and Cu became much better after citric acid, but the acidity and organic content of soil was worse than before. Alkaline soil transfered to acid soil and organic content had dropped with 30%.(3) Remediation of electrokinetic combining with Washing had a better removal rate result with 91.04% and 84.69%. The metal became stable with the improvement of residual form and organic matter-sulfide bounded form. The toxicity of metal was reducing. This remediation showed better in soil pH and organic content.The study of electrokinetic combining with washing remediation on artificial polluted soil could be a reference for remediation of the actual polluted soil. It showed an excellent result by changing the concentration of citric acid. It also could give an idea for developing new technology to remediation heavy metal polluted soil with low cost and high efficiency.