考虑降解时有机污染物在完好复合衬垫中的扩散分析

Analysis of organic contaminant diffusion through intact composite liners considering degradation

建立有机污染物在土工膜+压实黏土衬垫(CCL)和土工模+土工复合膨润土衬垫(GCL)复合衬垫中的一维扩散模型,同时考虑有机污染物在衬垫中的降解作用,得到模型的解析解。在此基础上,探讨土工膜中非稳态与稳态过程、不考虑土工膜等条件下有机污染物的运移特征,对比复合衬垫底部污染物通量的差异。研究结果表明:降解参数对有机污染物在CCL复合衬垫中的迁移有较大影响,在分析CCL复合衬垫中有机污染物的扩散运移时,需要考虑降解作用;将CCL复合衬垫简化为CCL单层衬垫分析时,误差很小,土工膜的作用可以忽略;对于GCL复合衬垫,由于GCL厚度很小,土工膜的作用不可忽略。

One-dimensional mathematical model for organic contaminant diffusion through geomembrane（GM）＋compacted clay liner（CCL） and GM＋geosynthetic clay liner（GCL） composite liners was developed to investigate the behavior of organic transport in the landfill liner system. Considering the degradation of the organic contaminants in the CCL or GCL, the analytical solution for the model was obtained. Migration characteristic of organic contaminant was studied under the conditions of steady-state diffusion in GM, unsteady-state diffusion in GM and without GM. The bottom fluxes of organic contaminants under the three conditions were compared. The results show that degradation parameters have a greater impact on the migration of organic contaminant in CCL composite liners, so the degradation can not be ignored. When the composite liner is simplified to single-layer CCL, the error caused by the simplification is very small. For GCL composite liner, geomembrane can not be ignored because the thickness of GCL is very small.