Jiangsu Key Laboratory of Urban Underground Engineering and Environmental Safety, Southeast University, Nanjing, 211189, Jiangsu Province, China.
Environ Sci Pollut Res Int. 2023 Apr;30(18):53702-53711. doi: 10.1007/s11356-023-26094-2. Epub 2023 Mar 3.
Landfill leachate-contaminated soil is widespread all over the world. In order to study the removal of mixed contaminants from landfill leachate-contaminated soil by flushing with bio-surfactant, soil column test was conducted to select an optimum concentration of bio-surfactant saponin (SAP) at first. Then, the removal efficiencies of organic contaminants, ammonia nitrogen, and heavy metals from landfill leachate-contaminated soil by flushing with SAP were studied. At last, the toxicity of contaminated soil before and after flushing was estimated by sequential extraction of heavy metals and plant growth test. The test results showed that the SAP solution with the concentration of 2.5 CMC could effectively remove the mixed contaminants from soil and would not introduce excessive pollutants of SAP in soil. Specifically, the removal efficiencies of organic contaminant and ammonia nitrogen were 47.01% and 90.42%, respectively. And the removal efficiencies of Cu, Zn, and Cd were 29.42%, 22.55%, and 17.68%, respectively. During flushing, hydrophobic organic compounds as well as physisorption and ion-exchange ammonia nitrogen in soil were removed by the solubilization effect of SAP, and heavy metals were removed by the chelation of SAP. After flushing with SAP, the reduced partition index (I) value of Cu and Cd increased, and the mobility index (M) value of Cu decreased. In addition, flushing with SAP reduced the plant toxicity of contaminated soil, and the residual SAP in soil promoted the plant growth. Therefore, flushing with SAP offered great potentials in remediating the landfill leachate-contaminated soil.
垃圾渗滤液污染土壤在全球范围内广泛存在。为了研究生物表面活性剂冲洗法去除垃圾渗滤液污染土壤中的混合污染物，首先进行了土壤柱试验以选择最佳生物表面活性剂皂素（SAP）浓度。然后，研究了 SAP 冲洗法去除垃圾渗滤液污染土壤中有机污染物、氨氮和重金属的效率。最后，通过重金属的顺序提取和植物生长试验来评估冲洗前后污染土壤的毒性。试验结果表明，浓度为 2.5CMC 的 SAP 溶液能有效去除土壤中的混合污染物，且不会在土壤中引入过量的 SAP 污染物。具体而言，有机污染物和氨氮的去除率分别为 47.01%和 90.42%。Cu、Zn 和 Cd 的去除率分别为 29.42%、22.55%和 17.68%。在冲洗过程中，SAP 的增溶作用去除了土壤中疏水性有机化合物以及物理吸附和离子交换氨氮，SAP 的螯合作用去除了重金属。SAP 冲洗后，Cu 和 Cd 的减少分配指数（I）值增加，Cu 的迁移指数（M）值降低。此外，SAP 冲洗降低了污染土壤的植物毒性，土壤中残留的 SAP 促进了植物生长。因此，SAP 冲洗在修复垃圾渗滤液污染土壤方面具有很大的潜力。
