Abstract: Compacted clay liner system with isolation and barrier function used in solid waste disposal is of low permeability. Diffusion, as a consequence, is the dominant pattern of leachate solute migration in the clay liner. In engineering practice, multicomponent contaminants coexist in the leachate of storage yards. In view of this, the diffusion law of multicomponent solute in the impervious clay liner is researched. An equation of multicomponent contaminants diffusion in clay liner is built by introducing the coefficient of activity which reflects the effective concentration of components based on the principle of linear momentum balance. Numerical solution is calculated by finite element software COMSOL Multiphysics. Results show that the introduction of coefficient of activity has hindered the transport progress of individual component. The results could be regarded as theoretical basis when designing economic and reasonable impervious barrier for storage yards.

Key words: multicomponent, diffusion of contaminants, coefficient of activity, clay lining, concentration of components