Performance prediction of a long crossflow reverse osmosis membrane channel

Abstract

Reverse osmosis membrane is often used in the form of a long membrane channel, in which the liquid under separation flows from one end to the other (crossflow). Permeate flux can vary significantly with location due to the substantial changes in the net driving pressure downstream in the channel. The conventional homogenous treatment of the long crossflow channel would result in erroneous recovery for highly permeable membranes. In this paper, the long crossflow membrane channel was treated as a heterogeneous system. A rigorous analytical model of recovery or average flux for the reverse osmosis membrane system was successfully obtained with the assumptions of complete salt rejection and constant driving pressure. The calculated recoveries were compared with experimental data from a 4-m long membrane channel. Results revealed that the performance of a long crossflow reverse osmosis membrane could be described effectively and accurately by the analytical model. © 2006 Elsevier B.V. All rights reserved.