Emerging membrane technologies for low-cost desalination

Abstract

Sustainable supply and utilization of water is required for the global economy and growth. In order to cater the needs, seawater desalination by membrane technique, reverse osmosis (RO), have become more attractive to produce potable water. Despite the potential advantages of RO process, it has limitations like low water recovery, low selectivity, membrane fouling, high energy requirement and brine disposal. Recent progress and developments in membrane materials, membrane modules and processes had laid foundation to novel technologies. Membrane distillation (MD), forward osmosis (FO) and pressure retarded osmosis (PRO) are emerging as niche area of research for seawater desalination. It is noteworthy to mention that advances in FO and MD for desalination allows the entire operation at low hydraulic pressure, which reduces the fouling and improves the membrane life. Whereas PRO is an osmotically driven process that produces the green energy from the brine stream. On the other hand, hybrid desalination processes in combination with RO, emerging technologies and renewable energy sources are found to be efficient compared to stand alone technology with a reduced desalination cost. Although a wide number of literatures are available, but practical integration of current state-of-the-art and its gradual progress is rarely addressed. In this context we represent emerging FO, MD and PRO processes, its principles, development of membranes for energy minimization and improved performance. Various configurations of hybrid processes in combination with renewable energy resources have been evaluated. Significant technological development and emergence of new materials is anticipated to play the pivotal role to make membrane-based desalination technologies more efficient, green, and economical in near future.