Overview of hybrid desalination systems - current status and future prospects

Hybrid desalination systems combining both thermal and membrane desalination processes with power generation systems are currently, considered a good economic alternative to dual-purpose evaporation plants. Hybrid (membrane/ thermal/power) configurations are characterized by flexibility in operation, less specific energy consumption, low construction cost, high plant availability and better power and water matching. In this paper the state-of-the-art of simple and fully integrated hybrid desalination systems is reviewed. In recent years, the concept of simple hybrid multistage flash-reverse osmosis (MSF/RO) configuration has been applied to a number of existing or new commercial desalination plants. The SWCC Jeddah, Al-Jubail and Yanbu existing power/water cogeneration plants are expanded for more water production by combining with new SWRO desalination plants. The simple hybrid desalination arrangement enabled the increase of the water to power ratio and utilized effectively the available intake/outfall facilities. A large hybrid 100 MIGD SWRO/MSF desalination plant was recently built in Fujairah, UAE. In this paper, salient features of commercially available hybrid desalination plants will be highlighted. A promising approach for pretreatment of seawater make-up feed to MSF and SWRO desalination processes using nanofiltration (NF) membranes has been introduced by the R&D Center (RDC) of SWCC. NF membranes are capable to reduce significantly scale forming ions from seawater, allow high temperature operation of thermal desalination processes, and subsequently increase water productivity. This paper provides an overview of research endeavors carried out by RDC to develop NF/MSF and NF/SWRO/MSF hybrid desalination systems. The developed fully integrated systems result in high water productivity and enhance thermal performance compared to the currently used simple hybrid desalination arrangements.