Techno-economic evaluation of forward/reverse osmosis hybrid system for saline water desalination

Forward osmosis (FO) hybrid systems have been developed recently as an alternative to conventional high-pressure membrane processes (reverse osmosis (RO)) for seawater desalination and wastewater treatment and recovery. However, the technical economic comparison with the RO processes for seawater desalination has not been clearly studied. The main objective of this investigation is to evaluate the detailed technical and economical feasibilities of the forward/reverse osmosis hybrid process for saline water desalination. The achievement of this study was conducted with the development of an economic model to calculate the effect of osmotic dilution of seawater feed stream on membrane area. A process design for hybrid FO/RO system for the simultaneous treatment of impaired and saline water with a pre-determined capacity, including material balance calculations, equipment sizing and selection were represented in this paper. Preliminary economic studies of the proposed systems for selected two cases were under taken: Ezz Steel Company treated wastewater with seawater, and El-Salam Canal water with brackish water. The results indicated that the application of FO/RO hybrid system for desalination is a promising system in the case of high TDS draw solution (such as seawater) but it is not beneficial in the case of low TDS draw solutions (such as brackish water).