A NOVEL-APPROACH FOR MODELING CONCENTRATION POLARIZATION IN CROSS-FLOW MEMBRANE FILTRATION BASED ON THE EQUIVALENCE OF OSMOTIC-PRESSURE MODEL AND FILTRATION THEORY

A theoretical model for prediction of permeate flux during crossflow m embrane filtration of rigid hard spherical solute particles is develop ed. The model utilizes the equivalence of the hydrodynamic and thermod ynamic principles governing the equilibrium in a concentration polariz ation layer. A combination of the two approaches yields an analytical expression for the permeate flux. The model predicts the local variati on of permeate flux in a filtration channel, as well as provides a sim ple expression for the channel-averaged flux. A criterion for the form ation of a filter cake is presented and is used to predict the downstr eam position in the filtration channel where cake layer build-up initi ates. The predictions of permeate flux using the model compare remarka bly well with a detailed numerical solution of the convective diffusio n equation coupled with the osmotic pressure model. Based on the model , a novel graphical technique for prediction of the local permeate flu x in a crossflow filtration channel has also been presented. (C) 1998 Elsevier Science B.V.