Utilisation of solar thermal energy in forward osmosis (FO) can provide an attractive method for seawater desalination. This study presents a novel process for the regeneration of dimethyl ether (DME) as a draw solute in FO using thermal energy from a solar pond. The location considered for this process is Chabahar (Iran) which benefits from a very high solar irradiance and access to an abundance of seawater from the Sea of Oman making it an ideal location for the proposed process. The average daily volume of desalinated water produced using this process coupled to a solar pond of 10,000 m2 was determined. It is indicated that a solar pond of such moderate size can drive a forward osmosis plant to provide 5,210 m3 of freshwater in the first two years of operation in Chabahar. The proposed process provides freshwater at varying rates throughout the year and benefits from a very low electricity consumption rate of 0.46 kWh per cubic metre of desalinated water offering a viable option for solar desalination. Considering that there are vast uninhabited coastal areas particularly in the Middle East and North Africa (MENA) region, the proposed method can contribute towards addressing the growing potable water scarcity

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A two-step forward osmosis (FO) desalination process combining both FO and reverse osmosis (RO) systems has been developed by the Centre for Osmosis Research and Applications at the University of Surrey and commercialised by Modern Water plc. In the FO + RO process seawater was used as feed water (FW) and a concentrated aqueous solution was used as a draw solution (DS). By taking advantage of natural osmosis, pure water is transferred from the FW to the DS and then recovered from the DS by the RO process utilising low resistance membranes, and hence lower specific energy consumption (SEC). This paper presents results of FO experiments conducted on flat sheet membrane using a bench-scale rig. The osmotic agent investigated in this study was magnesium sulphate, which is non-toxic, and highly soluble in water. Furthermore experiments were carried out on the RO pilot in order to regenerate the DS for reuse in the FO process and produce clean water. This paper also presents some pilot plant results and data from commercial plants in Oman and Gibraltar. The data demonstrates the efficiency of the FO + RO compared with the conventional RO process in terms of SEC and membrane fouling performance.

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