Emerging membrane technologies for low-cost desalination

Reverse osmosis (RO) has become an attractive option to produce potable water to cater the global needs. Despite the potential advantages of the RO process, it has limitations too. To address such limitations membrane distillation (MD), forward osmosis (FO) and pressure-retarded osmosis (PRO) are now becoming emerging areas of research for seawater desalination. With significant advances in FO and MD for desalination, the entire operation to be conducted at low hydraulic pressure, which reduces fouling and improves membrane life. PRO is an osmotically driven process that produces green energy from the brine stream. However, hybrid desalination processes in combination with RO, are found to be efficient compared to stand-alone technology, with a reduced desalination cost. Although a few studies are available, practical integration of the current state of the art and its gradual progress is rarely addressed. In this context, emerging FO, MD, PRO processes, and the development of membranes for energy minimisation with improved performance are presented herein. Hybrid processes in combination with renewable energy resources are evaluated. Significant technological development and emergence of new materials is anticipated to play a pivotal role so that membrane-based desalination technologies become more efficient and economical in near future.