Membrane filtration in municipal and industrial wastewater treatment is a technology being, increasingly employed to enhance the quality of purified water, increase the productivity of existing plants, and build smaller, yet more effective purification processes. Barrier to a breakthrough of the technology is the increased operational cost due to fouling and membrane replacement. Simulation studies with rigorous process models are a powerful tool to increase the understanding of the process and its decisive characteristics in order to design optimal processes and efficient operational strategies. In this paper, two enhancements of existing modeling approaches are proposed. One is taking into account the adhesive forces between the particles and the membrane surface, which indeed strongly effect cake layer formation and back flushing efficiency. The other is assessing the decisive influence of particle and membrane pore size distributions on both cake layer formation and pore blocking and their mutual dependencies. Both phenomena are essential characteristics which need to be considered for a reliable prediction of process behavior. The model is successfully tested in simulation studies and compared to experimental data from a pilot wastewater treatment plant with submerged hollow fiber membranes.