Denitrification of drinking water in poly (vinyl alcohol) pellets by reduction with the aid of hydrogen and PdCu catalyst particles, which were immobilized inside the pellet, was modeled by the Stefan-Maxwell approach. Pure diffusivities of potassium nitrate were calculated using Molecular Dynamics. To obtain effective diffusion coefficients, the structure of a cryogel was first simulated by the ISING-model on a cubic lattice. The diffusion coefficients then result from the following lattice gas Monte Carlo simulation.