Research advances in forward osmosis membrane separation

Forward osmosis(FO)is a concentration-driven membrane process,in which water transports across a semi-permeable membrane from a dilute feed solution into a concentrated draw solution.The basic factors of FO(driving force,draw solution and membrane materials)are introduced.The major hindrance to permeate water flux performance is the prevalence of concentration polarization on both sides of the membrane.Flux models that account for the presence of both internal and external concentration polarization for the two possible membrane orientations are presented.Internal concentration polarization is found to play a significant role in the reduction of driving force.This article comments the effect of membrane material,feed solution concentration,and draw solution concentration on FO and pressure-retarded osmosis(PRO)water flux performance.In addition,membrane fouling as well as energy consumption of FO is evaluated.