Advection and dispersion of Cl- in clay-bentonite barriers
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Abstract
Abstract: Clay-bentonite barriers composed of clay and bentonite mixtures are proposed to delay contaminant migration from landfills. Diffusions of ![]()
in the clay-bentonite mixtures with different contents of bentonite are analyzed by means of laboratory tests. The test results are fitted by an empirical formulation and an analytic solution respectively to get the effective diffusion coefficient. The feasibility of using the clay-bentonite barriers to prevent pollution by the contaminant in non-sanitary landfills is discussed. The test results show that the hydraulic conductivity and the effective diffusion coefficient of the clay-bentonite mixture decrease greatly as the content of bentonite increases. According to the tests, the logarithmic values of the hydraulic conductivity and the effective diffusion coefficient show a linear relationship with the bentonite content. The effective diffusion coefficient obtained from the analytical method is more accurate than that obtained from the empirical formulation because both effects of the diffusion and the advection on migration of ![]()
are considered in the analytical method. Advection-diffusion analysis is carried out considering leachate heads of 30 cm and 3 m on the bottom of a landfill. The results show that the surroundings are prone to being polluted by non-sanitary landfills and that the pollution can be effectively avoided or delayed by the clay-bentonite barriers.
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