反应参数衰减时复合衬垫有机污染物运移半解析模型

Semi-analytical model for transport of organic contaminants in composite liners considering attenuation of reaction parameters

为了研究土工膜下卧黏土衬垫中有机污染物的吸附与降解等反应参数随深度衰减特性对复合衬垫防污性能的影响,将反应参数的衰减用具体函数表示,通过拉氏变换得到了有机污染物在复合衬垫中的一维运移半解析解。通过现场试验数据验证了该半解析模型。无量纲分析结果表明,压实黏土衬垫CCL中参数衰减较快时(β=0.1),能使击穿时间缩短68%;当扩散和降解作用主导时(如Pe2≤1和Q≥10),衰减效应对通量和浓度影响能超过40%,但当对流作用占主导并且降解较弱时(如Pe2≥10和Q≤1),反应参数的衰减效应可以忽略。不考虑反应参数的衰减时,亲水性有机污染物和疏水性有机污染物的击穿浓度可分别低估近61%倍和37%。该解能更好地模拟现场监测数据,评估填埋场衬垫的有效性,可用于复合衬垫的设计和复杂数值模型的验证。

In order to investigate the influences of the attenuating characteristics of reaction parameters including adsorption and degradation in the clay liners under the geomembrane on the antifouling performances of composite liners,the attenuation of reaction parameters is expressed as a specific function.The one-dimensional semi-analytical solution for transport of organic contaminants in composite liners is obtained by the Laplace transformation.The semi-analytical model is validated through the field test data.The results of dimensionless analysis show that when the reaction parameters in CCL decrease rapidly with the increase of depth(e.g,b=0.1),the breakthrough time can be reduced by 68%.The bottom concentrations and fluxes can be reduced by 40%when the diffusion and degradation dominate transport of contaminants(e.g.,Pe2≤1 and Q≥10).The attenuation effects of the reaction parameters can be ignored when the advection is the dominant process(e.g.,Pe2≥10 and Q≤1).Without considering the attenuation of reaction parameters,the breakthrough concentration of hydrophilic organic contaminants and hydrophobic organic contaminants can be underestimated by 61%and 37%respectively.The field monitoring data can be better fitted by the proposed model,and it can be used to evaluate the effectiveness of landfill liners.It can also be used for the design of composite liners and the verification of complex numerical models.