Experimental Study on In-situ Leaching and Electrokinetic Remediation of Composite Heavy Metal-contaminated Soil

摘要

[Objectives] This study was conducted to investigate in-situ leaching and electrokinetic combined remediation of composite heavy metal-contaminated soil.[Methods] Leaching and electrokientic combined remediation was applied to remediate artificially-simulated composite Cd,Cu,Pb,and Zn-contaminated soil.The electrokinentic remediation of the soil was carried out using EDTA and acetic acid as the eluents with electrodes placed on the top and bottom of the soil,to investigate the effects of different types and concentrations of eluents,reaction time and energization methods on the remediation.[Results]Applying electrodynamic force to the leaching remediation process achieved good removal effects of Cd,Cu,Pb,and Zn in the soil.Compared with pure leaching,the leaching and electrokinetic combined remediation saved 23.8% of EDTA consumption.EDTA showed the ability to complex heavy metals better than acetic acid,and after 10 d of reaction,the 0.1 mol/L EDTA achieved very good removal effects on Cd,Cu,Pb,and Zn from the upper and middle layers of the soil column,exhibiting removal rates of 94.4%,93.3%,91.4% and 92.8% in the upper layer and 87.2%,88.2%,83.3% and 84.6%,respectively.Compared with the conventional experiments,the intermittent energization method and the voltage-increasing method improved the removal rates of Cd,Cu,Pb and Zn by 6.3%,6.1%,5.9%and 6%,and 0.6%,0.9%,0.5% and 0.4%,respectively,and saved 46.8% and 10.3% of energy consumption,respectively.[Conclusions]The study provides reference for the remediation of composite heavy metal-contaminated soil.