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A novel theory is developed for concentration polarization of non-interacting particles in crossflow-filtration systems. This theory reveals that the extent of concentration polarization, a s well a s the behaviour of the permeate flux, a r e characterized by an important dimensionless filtration number (N, = 4m:Ai3/3k~). There is a critical value of the filtration number for a given suspension and operational conditions. When the filtration number is smaller than the critical value, a polarization layer exists directly over the membrane surface and the wall particle concentration is determined by the pressure and temperature. At higher filtration numbers, a cake layer of retained particles forms between the polarization layer and the membrane surface. Mathematical models a r e constructed for both c a s e s and analytical solutions for the permeate flux a r e derived. An increase in permeate flux with increasing pressure is predicted for all operational conditions.

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