Advances in forward osmosis (FO) technology for enhanced efficiency and output: A critical review

Abstract

Freshwater scarcity is one of the most important issues facing the world today. To address this issue, processes have been developed to purify and desalinate water at an industrial scale, especially based on membrane reverse osmosis (RO). However, because of the drawbacks of conventional RO – including the inability to handle high salinity and susceptibility to fouling – forward osmosis (FO) has been introduced as a complementary technology. FO can be coupled with other desalination techniques like membrane distillation and RO to remedy these issues. We aim here to review recent advances in FO and the challenges facing this technology. Important parameters in FO operation include transmembrane water flux and output, energy consumption, fouling, draw solution type and regeneration, and membrane type. Several methods to increase the water flux are discussed, including changes in system temperature, development and alterations in draw solution (DS) properties, modeling and development of new membranes, and techniques to reduce concentration polarization. These developments help to increase water flux and water recovery and to mitigate membrane fouling and concentration polarization. We also discuss the various applications of these novel techniques in different areas, and how they can improve the efficiencies of hybrid systems. Finally, we make recommendations for future developments, to allow the use of FO at a large scale in water purification systems.