A review of resource recovery from seawater desalination brine

Abstract

In order to address freshwater scarcity, seawater desalination technologies have been widely studied in recent years. However, the disposal of desalination brine which contains an even higher concentration of salts than seawater can potentially damage the surrounding environment. Therefore, alternative approaches aiming to recover valuable resources from desalination brine have been conducted. Three resources that can be recovered have been studied in this paper, which are minerals, freshwater and energy. The techniques to recover minerals can be divided into pressure-driven techniques, thermal-driven techniques, electro-driven techniques and other techniques. The water recovery techniques employ mainly membrane/thermal integrated hybrid processes, while the energy recovery techniques such as pressure retarded osmosis (PRO) and reverse electrodialysis (RED) utilize the salinity gradient energy (SGE) to generate energy. The valuable mineral products have also been reviewed in this paper in terms of recovery methods, performance of processes and product quality. The reviewed products are sodium salts (NaCl, NaOH, Na2SO4), lithium salts (LiCl, Li2CO3), magnesium salts (struvite, Mg(OH)2, MgSO4, MgO), calcium salts (CaSO4, CaCO3) and other minerals (U, Rb, Cs). Based on the cost and revenues of each technique, an economic comparison has been conducted along with the cost analysis of operating desalination plants.