11 - Reverse osmosis and forward osmosis in integrated systems

Abstract

Since the osmotic pressure as driving force in forward osmosis is created by the osmotic gradient between feed solution and draw solution, the posttreatment of draw solution is generally required and conducted by reverse osmosis to recover product water and reuse draw solutes. Therefore, forward osmosis and reverse osmosis are often combined to be an integrated membrane system. The integrated forward osmosis-reverse osmosis system has been studied for saline water desalination, wastewater treatment, and renewable energy generation. The harsh fouling of conventional reverse osmosis process can be converted to reversible fouling of forward osmosis in the integrated system. It is possible to perform the desalination, water treatment, and energy generation simultaneously by employing different water (such as quality impaired water, saline water, and concentrated brine) in the integrated system. The integrated forward osmosis-reverse osmosis membrane system can play a promising role for the comprehensive management of water resource and promote the sustainability in water-energy nexus.