Critical Review of Reverse Osmosis and Pretreatment Techniques of Inland Desalination Plants

Freshwater, which accounts for less than 1% of world water resources, is rapidly decreasing due to extreme levels of withdrawals and the influence of seawater in areas under tension. This decreasing trend has reached a critical level in the Middle East since the water per capita in this area is much lower than the world average. Desalination is an approach for reducing water stress by producing freshwater from seawater, saline groundwater, drainage water, and wastewater in the coastal and inland areas. During these processes, rejected streams with high salinity as a sub-product are produced in which disposing of them is costly. A large amount of concentrated water containing the remaining compounds discharge into the environment and is potentially considered as a serious problem. Inland desalination due to the impossibility of disposing the produced brine is different from the desalination of seawater. In desalination of underground saline waters, fouling occurs with water-soluble salts and sedimentation reduces the production of water with a certain amount of energy during these processes. Therefore, the evolution of desalting technologies makes it cheaper, more reliable, and less productive.