Forward Osmosis: Current Status and Perspectives

Study Shows Forward Osmosis Desalination Not Energy Efficient

Forward osmosis (FO) is a natural process for water transfer through a selectively permeable membrane driven by the osmotic pressure difference across the membrane. Starting from Sidney Loeb's pioneering work in pressure-retarded osmosis (PRO) three decades ago published in the first issue of the Journal of Membrane Science (January, 1976), there has been a resurgence of interest in various osmotic processes in recent years. The renewed attention comes from the potential to either reduce energy consumption in wastewater treatment, water purification and seawater desalination, or produce energy from salinity-gradient energy harvesting, etc.

However, there are a number of technical barriers that impede FO's industrial applications. The major challenges to be overcome include (i) the lack of an ideal draw solution that exhibits high osmotic pressure and can be easily regenerated to produce pure water; and (ii) the lack of an optimized membrane that can produce a high water flux, comparable to commercial RO membranes, with low salt transmission, and possessing effective anti-fouling properties. In addition, a suitable module design is required to maintain long-term system performance for specific applications, etc. This virtual special issue of the Journal of Membrane Science provides the state-of-the-art of FO technology, including the contributions from the membrane community to address the above-mentioned challenges over the period from 1976 to June 2012.

Concluding remarks

Osmotically driven membrane processes are remarkable new and green technologies and have attracted extensive studies in recent years. Considerable R&D outcomes for FO have been published in the Journal of Membrane Science, in its role as the premier journal in the membrane field. The research activities are mainly focused on novel FO/PRO membrane development (28%), exploration of various applications of osmotic processes (24%), fundamental understanding of concentration polarization and modeling (21%), membrane fouling control (10%), invention of new draw solutes (8%) and module design (7%). The people most actively involved in this field currently include Elimelech's group, Cath and Childress's groups and McCutcheon's group in the United States, Chung's group and the Wang-Tang-Fane group in Singapore.

It is anticipated that the efforts from the membrane community will continue to achieve technology breakthroughs in novel FO membranes and draw solute developments in the near future. This virtual special issue is expected to provide a platform for easy access to state-of-the-art FO technology so as to facilitate further FO technology development.

Appendix: List of forward osmosis papers published in Journal of Membrane Science up to June 2012

Source: Elsevier

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Taxonomy

• Desalination
• Forward Osmosis