EK-PRB联合酵母菌对镉污染土壤修复研究

Remediation of Cd-contaminated soil by EK-PRB combined with yeast

运用固定化微生物技术制备粉煤灰-酵母菌小球,联合电动-可渗透反应墙(EK-PRB)技术,研究电压梯度和PRB材料对于Cd污染土壤修复效果的影响。试验修复周期设定为120 h,初始含水率为30%,电解液为CA和EDTA,设置6组电压梯度(1.0,2.0,3.0,4.0,5.0,2.5 V/cm),进行试验得到最适合的电压梯度后,再对比PRB材料(粉煤灰-酵母菌小球、粉煤灰)的影响,共计7组试验。结果表明,电压梯度在1.0~5.0 V/cm范围内增加对Cd去除有促进作用,Cd去除率可提高23.4%,粉煤灰–酵母菌小球作为PRB材料对Cd污染土壤修复效果更好。考虑电能消耗成本与应用,选择电压梯度2.5 V/cm,PRB材料为粉煤灰-酵母菌小球,Cd去除率可达53.7%,体现了固定化微生物联合EK-PRB技术的可行性以及修复优势,为后续深入研究去除机理以及材料创新提供基础支撑。

The influence of voltage gradient and permeable reaction barrier(PRB) material on the remediation of Cd-contaminated soil was studied by immobilized microorganism technology to prepare fly ash-yeast pellets,and combined with electrokinetic-permeable reaction wall(EK-PRB) technology.The repair period was set at 120 h;the initial water content was 30%;the electrolyte was CA and EDTA.Six sets of voltage gradients(1.0,2.0,3.0,4.0,5.0,2.5 V/cm) were set,and the most suitable voltage gradient was obtained.The effect of PRB materials(fly ash-yeast pellets,fly ash) were compared.A total of seven sets of tests were conducted.The results showed that the increase of voltage gradient in the range of 1.0~5.0 V/cm has a facilitating effect on Cd removal,and the removal rate of Cd can be increased by 23.4%.Fly ash-yeast pellets are more effective as PRB materials for the remediation of Cdcontaminated soil.Considering the cost of electrical energy consumption and application,the voltage gradient is selected as 2.5 V/cm and the PRB material is fly ash-yeast pellets.The removal rate of Cd can reach 53.7%,which reflects the feasibility and remediation advantages of immobilized microorganisms combined with EK-PRB technology,and provides basic support for the subsequent indepth study of the removal mechanism and material innovation.