Transport of volatile organic compounds through PVC and LLDPE geomembranes from both aqueous and vapour phases

Abstract

The diffusive migration in the aqueous and vapour phases of four volatile organic compounds (VOCs: benzene, toluene, ethylbenzene and xylenes) through samples of 0.76 mm (30 mil) thick flexible poly-vinyl chloride (PVC) and 0.76 mm (30 mil) linear low-density polyethylene (LLDPE) geomembranes are compared based on both sorption and diffusion tests. Diffusion coefficients for the PVC geomembrane were in the range of 5.0–10 × 10−13 m2/s for diffusion from both the aqueous and vapour states. The range for LLDPE was 2.5–5.0 × 10−13 m2/s. Diffusive transport of VOC contaminants through geomembranes in a simulated landfill environment (i.e. in the presence of water vapour) is identical despite the phase they originated from, simplifying the analysis of contaminant transport. The partitioning (sorption) coefficients for PVC were in the range 100–1075 with respect to aqueous phase concentrations. The corresponding values with respect to vapour phase concentrations were 22–290. LLDPE partitioning (sorption) coefficients were 200–475 with respect to aqueous phase concentrations and 44–123 with respect to vapour phase concentrations.

Potential solution to pollution of groundwater by diffusion of volatile organic compounds through the primary HDPE geomembrane in composite lining systems of landfills

“…The two GMs would be identical and the theory applied for the calculation of the sorption and diffusion coefficients will remain. A study by McWatters and Rowe (2009) investigated the transport of VOCs through GMs from both aqueous and vapour phases and found that: "… diffusive transport of VOC contaminants through geomembranes in a simulated landfill environment is identical despite the phase they originated from, simplifying the analysis of contaminant transport".…”

“…Diffusion tests were done following the examples given in the work by McWatters and Rowe (2009) to determine the rate of diffusion of the VOCs through the HDPE GM by measuring the change in concentrations of solutions on either side of the HDPE GM. Diffusion tests were carried out in three phases.…”

A review of the performance of geosynthetics for environmental protection

“…The diffusion coefficient can be obtained from doublecompartment tests (Islam and Rowe, 2009;McWatters andRowe, 2008, 2010;Sangam andRowe, 2001, 2005;Touze-Foltz et al, 2012b) or immersion tests (Park et al, 2012).…”

Breakthrough time-based design of landfill composite liners

“…The main mechanism for inorganic contaminant transport in the composite liners is advection through GMB defects and advection-dispersion in the underlying GCL, CCL, or attenuation layer (Rowe, 2005;Varank et al, 2011). Unlike inorganic contaminants, organic contaminants can readily transport through intact GMB by molecular diffusion (Edil, 2003;Chen et al, 2009;McWatters and Rowe, 2009, 2014Mendes et al, 2014;Shackelford, 2014). Cleall and Li (2011) provided an analytical method for the design of landfill composite liners considering pure diffusion.…”