College of New Energy and Environment, Jilin University, Changchun 130021, People's Republic of China; Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, People's Republic of China.
School of Hydrology and Water Resources, Nanjing University of Information Science and Technology, Nanjing 210044, People's Republic of China.
Sci Total Environ. 2022 Oct 20;844:157167. doi: 10.1016/j.scitotenv.2022.157167. Epub 2022 Jul 2.
Cadmium (Cd)-containing wastewater has been used to irrigate agricultural land. However, long term usage has resulted in the accumulation of Cd in the soil systems, which can eventually leach into the aquifer, contaminating groundwater. Microbial-induced carbonate precipitation (MICP), an economical and effective method, was used to block the in situ migration of Cd in the soil profile. The results of the laboratory experiments showed that the maximum Cd adsorption capacity of the soil exposed to MICP (8.92 mg/g) was higher than that of soil without MICP (7.12 mg/g). The Thomas model provided a good fit for the Cd migration process in soil exposed to MICP (R > 0.96), and Cd was trapped more effectively by soil exposed to MICP than by soil alone. Further testing showed that the Cd retention time in the MICP soil column increased with increasing soil urea content and pH but decreased with increasing flow rate. Soil physico-chemical properties showed that the MICP process increased the soil particle size and Cd capacity and decreased the proportion of exchangeable Cd in the soil. Scanning electron microscopy and X-ray diffraction analyses confirmed the generation of CdCO in the MICP soil column. The findings of this study indicate that MICP can be effectively used to immobilize Cd and prevent its migration in the soil profile.
含镉废水已被用于灌溉农田。然而，长期的使用导致镉在土壤系统中积累，最终可能会渗滤到含水层中，污染地下水。微生物诱导碳酸钙沉淀（MICP）是一种经济有效的方法，用于阻止土壤剖面中镉的原位迁移。实验室实验结果表明，暴露于 MICP 的土壤的最大镉吸附容量（8.92mg/g）高于未暴露于 MICP 的土壤（7.12mg/g）。Thomas 模型很好地拟合了暴露于 MICP 的土壤中镉的迁移过程（R>0.96），并且暴露于 MICP 的土壤比单独的土壤更有效地捕获了镉。进一步的测试表明，MICP 土壤柱中镉的保留时间随着土壤尿素含量和 pH 值的增加而增加，但随着流速的增加而减少。土壤理化性质表明，MICP 过程增加了土壤颗粒大小和镉容量，降低了土壤中可交换镉的比例。扫描电子显微镜和 X 射线衍射分析证实了 MICP 土壤柱中生成了 CdCO。本研究结果表明，MICP 可有效用于固定土壤中的镉，防止其在土壤剖面中迁移。
