Experimental Determination of Sorption and Diffusion of Organic Pollutants through GCLS

Compared to the United-States where mainly Wyoming natural sodium bentonite is used, Europe is facing a variety of GCLs containing either natural sodium bentonites, natural calcium bentonites or Na-activated Ca bentonites. Furthermore the manufacturing process of GCLs varies from manufacturer to manufacturer in terms of geotextiles used and mode of assembly of the GCL (needlepunched or stitch for example). The question then arises of the performance of landfill composite bottom liners depending on the nature of the GCL. An adequate modelling of contaminant advective-diffusive flow through GCLs requires the quantification of sorption parameters of the geotextile and bentonite components of those materials for a variety of contaminants contained in leachate, as well as the quantification of diffusion coefficients. The aim of this paper will thus be to present the experimental results obtained regarding sorption on various constitutive geotextiles from GCLs of 4 volatile organic compounds (VOCs). Indeed these pollutants seem to be potentially dangerous substances for human health according to their amount found in leachate and their Toxicology Reference Value (TRV). 2 GCLs from two different manufacturers were selected for this study. They are both made of two polypropylene geotextiles, a woven and a nonwoven, which encapsulate bentonite. The nature of the geotextiles differ from one manufacturer to the other. Preliminary results regarding partitioning coefficients will be presented together with preliminary results of 1,2-dichloroethane diffusion through one of the GCLs.