Analytical solutions for contaminant diffusion in two-layered porous media considering degradation

The organic contaminants are always more harmful to the environment than the inorganic ions. One-dimensional mathematical model for organic contaminant diffusion through two-layered porous media is developed to investigate the behavior of organic transport in the landfill liner system. Degradation of the organic contaminants in the porous media is considered. The bottom boundary conditions are assumed to be zero concentration or zero flux. The analytical solutions for the mathematical model are obtained by means of the method of separation of variables. The results obtained by the proposed analytical solution agree well with those obtained by the commercial software POLLUTE v7. The effect of degradation on organic contaminant diffusion through the layered media is investigated on the basis of the proposed solutions. The bottom concentration and flux of the soil liners can be greatly reduced when the degradation effect is considered. The bottom flux for the liner system with the half-lives of 5-10 years can be 4-8 times less than those assuming no degradation. Compared to that of the lower layer, the effect of the degradation of the upper layer is more important on reducing the organic concentration in the underlying environment.