HYDRODYNAMIC ASPECTS OF CROSS-FLOW MICROFILTRATION - ANALYSIS OF PARTICLE DEPOSITION AT THE MEMBRANE-SURFACE

During a crossflow microfiltration operation, particle deposition is the first, and one of the major reasons, for flux reduction and fouling. The hydrodynamic field at the proximity of the filter surface is determined and discussed under various filtration conditions. A two-dimensional finite-element model is developed in order to compute the fluid flow near one or several square pores uniformly distributed on a flat plate modelling the membrane surface. This study at pore level confirms the existence of two flow structures which determine the possibility of particle deposition. Finally a simplified model of particle trajectories is proposed. The balance of forces takes into account Van der Waals and Stokes forces. Results show the particle deposition on the membrane surface.