Dynamics and characterisation of membrane fouling in a long reverse osmosis membrane channel

Abstract

Fouling alleviation and control in long reverse osmosis (RO) membrane channel is seriously hindered by ineffective fouling characterization. It has been realized that SDI and related indices are not capable of quantifying fouling strength of all possible foulants in feed water to RO membranes and average permeate flux is not sensitive to the initial fouling development under certain operating conditions. In this study, an advanced characterization method to effectively reflect and accurately quantify fouling is developed. The behavior of permeate flux in long RO membrane channel is first investigated. A new fouling potential that includes all foulants to RO membrane is proposed for more accurate quantification of feed water fouling strength. By treating the membrane channel as a heterogeneous system, the fouling potential can be readily used to predict fouling development in long membrane channel. An operational technique is also developed to effectively reflect fouling in RO processes, even when no obvious flux decline is observed.