An analytical model for vapor‐phase volatile organic compound diffusion through landfill composite covers. (18th February 2016)

• Record Type: Journal Article
• Authors: Xie, Haijian; Yan, Huaxiang; Thomas, Hywel R.; Feng, Shijin; Ran, Qihua; Chen, Peixiong
• Is Part Of: International journal for numerical and analytical methods in geomechanics. Volume 40:Number 13(2016)
• Page Start: 1827
• Page End: 1843
• Publication Date: 2016-02-18
• Subjects: volatile organic compounds -- landfill -- composite cover barrier -- vapor diffusion -- analytical solution; Soil mechanics -- Mathematics -- Periodicals; Rock mechanics -- Mathematics -- Periodicals; 624.1510151
• DOI: 10.1002/nag.2514
• Languages: English
• ISSNs: 0363-9061

Abstract

Summary: One‐dimensional mathematical models for vapor‐phase volatile organic compound (VOC) diffusion through composite cover barriers are presented. An analytical solution to the model was obtained by the method of separation of variables. The results obtained by the proposed solution agree well with those obtained by a numerical analysis. Based on the proposed analytical model, the VOC breakthrough curves of five different composite covers are compared. The effects of degree of saturation of geosynthetic clay liner (GCL) or compacted clay liner (CCL) on VOC migration in the composite covers are then presented. Results show that the composite cover barriers provide much better diffusion barriers for VOC than the single CCL. The top surface steady‐state flux for a composite barrier, consisting of a 1.5 mm geomembrane (GM) and a 20 cm CCL, can be 8.3 times lower than that for a 30 cm CCL. The surface steady‐state flux for the case with (1.5 mm GM + 6 mm GCL) was found to be 2.3 times lower than that for the case with (1.5 mm GM + 20 cm CCL). The degree of saturation Sr of the CCL has a great influence on VOC migration in composite covers when Sr is larger than 0.5. The steady‐state flux at the surface of GM for the case with Sr = 0.7 can be 1.8 times lower than that for the case with Sr = 0.2. The proposed analytical model is relatively simple and can be used for verification of complicated numerical models, analysis of experimental data and performance assessment of composite cover barriers. Copyright © 2016 John Wiley & Sons, Ltd.