Coupling of PV-powered RO brackish water desalination plant with solar stills

Desalination of water is essential to supply sufficient good-quality water to remote areas to satisfy various needs. Saudi Arabia has enormous amounts of deep water, and the underground water in many areas of this country is so brackish that it requires extensive pre-treatment. In order to utilize inland reserves of brackish water by the local inhabitants, the Energy Research Institute (ERI) of King Abdulaziz City for Science and Technology (KACST) installed a photovoltaic- (PV) powered water desalination reverse osmosis (RO) plant in Riyadh, Saudi Arabia. The reject brine rate from this plant is very high. Due to the inherent advantages of solar still assemblies, for instance; simple to construct and maintain using locally available materials, and high technical feasibility in remote areas, a solar still plant capacity of 5.8 m(3) distillate per day is proposed to couple with the existing PV-RO plant in order to utilize most of the reject brine instead of releasing it into the ground. The estimated cost of product water obtained through this design is found to be Saudi Riyal 1.9 (US$0.50) per m(3). The proposed design of the solar still assemblies can be applied to configure a 100% solar-powered desalination system for any location and quality of brackish water.