In this paper, a solute transport problem with non-equilibrium adsorption in a non-homogeneous porous medium consisting of two zones, one with high permeability (mobile zone) and another one with low permeability (immobile liquid zone) are considered. In the mobile zone, there are two zones in both of which adsorption of solute with reversible kinetics occurs. The results of this approach are compared with known, traditional approaches. It is shown that this method of modeling the process gives a satisfactory result. By appropriate selection of the parameters of the source term, one can obtain results close to those of the well-known bicontinuum approach.