Simple technique for measuring the concentration polarization level in a reverse osmosis system

This paper describes the application of a simple technique for determining the mass transfer coefficient and the concentration polarization level in a reverse osmosis (RO) system. The technique is based on evaluation of the permeate flux decline induced by the addition of a salt solution to an initially salt-free water feed. Since the net pressure driving force is influenced by the level of the osmotic pressure prevailing on the membrane surface, the magnitude of flux decline enables the evaluation of membrane surface concentration, and hence the determination of the mass transfer coefficient k. The mass transfer coefficient is given by: