School of Architecture and Civil Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003, China; Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing, 210098, China.
Institute of Geotechnical Engineering, Yangzhou University, Yangzhou, 225127, China.
J Environ Manage. 2019 May 1;237:155-162. doi: 10.1016/j.jenvman.2019.02.051. Epub 2019 Feb 19.
Leachate contains composite contaminants, and the chemical compatibility of soil-bentonite cut-off walls is unclear. To better understand the issue, Fujian standard sand is used to represent a sandy soil stratum. Two clays were used as additive to examine the chemical compatibility of the soil-bentonite model backfills under the condition of composite contaminants. The results indicate that there is a representative cation when the backfills are permeated with NaCl, CaCl, and ZnCl solutions and an NaCl-CaCl-ZnCl mixed solution of the same ionic strength. Ca has the highest maximum ionic strength among all cations from leachates. Moreover, the change in hydraulic conductivity, bound water content and effective porosity of sand-bentonite with the Ca concentration or chemical oxygen demand (COD) exhibit a concentration threshold; i.e., when the concentration is smaller than the threshold, the hydraulic conductivity and effective porosity significantly increase, whereas the bound water content rapidly decreases; when the concentration is higher than the threshold, the hydraulic conductivity, bound water content and effective porosity tend to stabilize. In addition, under the condition of composite contaminants, the threshold is observed, while the hydraulic conductivity, bound water content and effective porosity vary with the COD. Thus, both the type and concentration of chemicals can change the effective porosity and affect hydraulic conductivity. Furthermore, there is a power function relationship between permeability and the effective pore.
淋滤液中含有复合污染物，且土壤-膨润土防渗墙的化学兼容性尚不清楚。为了更好地理解这个问题，采用福建标准砂来代表砂土地层。使用两种粘土作为添加剂，研究了复合污染物条件下土壤-膨润土模型衬垫的化学兼容性。结果表明，当回填料分别被 NaCl、CaCl2 和 ZnCl2 溶液以及具有相同离子强度的 NaCl-CaCl-ZnCl 混合溶液渗透时，存在一种代表性的阳离子。在所有来自淋滤液的阳离子中，Ca 具有最高的最大离子强度。此外，砂-膨润土的水力传导率、结合水含量和有效孔隙率随 Ca 浓度或化学需氧量 (COD) 的变化表现出浓度阈值；即，当浓度小于阈值时，水力传导率和有效孔隙率显著增加，而结合水含量迅速下降；当浓度高于阈值时，水力传导率、结合水含量和有效孔隙率趋于稳定。此外，在复合污染物条件下，观察到了阈值，而水力传导率、结合水含量和有效孔隙率随 COD 而变化。因此，化学物质的类型和浓度都可以改变有效孔隙率并影响水力传导率。此外，渗透率与有效孔隙之间存在幂函数关系。
