Analytical model for organic contaminant transport through GMB/CCL composite liner with finite thickness considering adsorption, diffusion and thermodiffusion. (1st February 2021)

• Record Type: Journal Article
• Authors: Peng, Ming-Qing; Feng, Shi-Jin; Chen, Hong-Xin; Chen, Zhang-Long; Xie, Hai-Jian
• Is Part Of: Waste management. Volume 120(2021)
• Page Start: 448
• Page End: 458
• Publication Date: 2021-02-01
• Subjects: Landfill -- Thermodiffusion -- Diffusion -- Composite liner -- Analytical model; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2020.10.004
• Languages: English
• ISSNs: 0956-053X

Abstract

Graphical abstract: Highlights: The present model can be used to design and evaluate GMB/CCL composite liners. Two typical bottom boundaries in engineering can be considered in the model. The molecular diffusion, thermodiffusion and adsorption can be simulated. When ST is not less than 0.01 K −1, the thermodiffusion effect should be considered. Thermal conductivity has little effect on the barrier performance of GMB/CCL. Abstract: A new analytical model for organic contaminant transport through GMB/CCL (geomembrane and compacted clay liner) composite liner is developed, which can consider adsorption, diffusion and thermodiffusion processes and is applicable for typical bottom boundary conditions. The separation of variables method is adopted to derive the solution. The present model is first verified against experimental results and a numerical model. The influence of thermodiffusion on organic contaminant transport in composite liner is then investigated. Toluene is adopted as the representative organic contaminant. The results reveal that when the Soret coefficient ST is not less than 0.01 K −1, the effect of thermodiffusion should be taken into account on the contaminant transport in GMB/CCL composite liner in wet landfills. When the Soret coefficient ST is 0.03 K −1, the breakthrough time of a GMB + 0.75 m CCL composite liner and a 2 m CCL would be overestimated by 20% to 76% due to omitting of the effect of thermodiffusion. Namely, the barrier performance would be greatly overestimated if the effect of thermodiffusion is neglected in these cases. In other aspects, the thermal conductivity of GMB and CCL has little effect on the contaminants transport in GMB/CCL composite liners, so there is no need to modify the materials for this parameter. The present model is an applicable tool for evaluating the barrier performance of the GMB/CCL composite liner, and can provide valuable advices for improving the liner materials.