EVALUATING BARRIER PERFOMANCES OF PVC-, LDPE-, HPDEGEOMEMBRANES AGAINST ORGANIC COMPOUNDS IN WASTE LEACHATE BY LONG-TERM IMMERSION TEST

The barrier performance of the geomembranes against benzene, toluene, xylene, fluorobenzene, trichloroethylene and tetrachloroethylene which are typical organic compounds was evaluated from the continuous batch tests. The process that the organic compounds diffuse into the geomembranes was modeled using the diffusion coefficient and the distribution coefficient, and those parameters were estimated by the model fitting on the experimental results. As the results, the distribution coefficients that mean the adsorbability to the surface of the geomembranes became higher in the order of HDPE, LDPE, and PVC sheet. Therefore, the HDPE sheet exhibited a superior barrier performance. In contrast, the effects of the geomembrane’s thickness on the distribution coefficients were minor. The diffusion coefficient that mean the diffusivity into the geomembranes had 10-14 to 10-12 m2/s for any geomembranes according to the results of the continuous batch tests. The diffusion coefficient was increased with the thickness of the geomembrane.