Comprehensive Evaluation of a Hybrid Forward Osmosis - Reverse Osmosis System for Wastewater Treatment, Desalination, and Energy Recovery

Forward osmosis (FO) technology, though gaining interest in the last two decades, is still regarded as non-economically viable option. In the light of the recent advances in FO membrane technology and potential benefits of its integration with reverse osmosis (RO) for desalination, wastewater treatment and energy recovery, a comprehensive analysis for FO-RO integration was carried out. This integration considers a layout which concentrates FO feed (wastewater) and dilutes the draw solution, producing potable water via RO and methane from the concentrate through upflow anaerobic sludge blanket in a separate energy recovery unit. Compared to mainstream technologies exemplified by the seawater reverse osmosis (SWRO), membrane bioreactor followed by reverse osmosis (MBR-RO), and Hitachi’s REMIX water system, this study reveals that FO-RO integration for both potable water production and energy recovery has become economically viable with a 9% life cost advantage over MBR-RO and a 20% advantage over SWRO and conventional activated sludge process combined. Moreover, the FO-RO integration showed a cost benefit ratio of 1.17, reflecting its economic viability. With ongoing advancements in FO technology and energy recovery and the many overlooked advantages it offers, this integration has the potential to become the new norm for desalination and wastewater treatment.