Brine management in desalination industry: From waste to resources generation

Desalination brine has high salinity and contains various chemical contaminants and its disposal causes a major concern for desalination around the world. Environmentally friendly and economically feasible methods are essential for sustainable management of desalination brines. On the other hand, adequate supply of various minerals is essential in meeting the increasing demands of growing populations across the world. Land-based mining industries suffer from limited supply of water and energy, depletion of high-grade minerals, environmental issues and various geopolitical conflicts. Although suffers from high cost, low recovery efficiencies and absence of mature technologies, seawater mining offers a potential solution for this. Seawater contains large quantities of various minerals, of which some are rare and expensive in their land-based forms. This can mitigate the mineral scarcity to some extent and reduce the desalinated water price significantly as we get an additional product from desalination. In addition, the environmental impacts associated with the brine discharge can be avoided as well. This paper reviews recent research and technologies on recovering resources from desalination brine. Major thermal and membrane technologies for recovering water, minerals and energy are included. Recent developments in solar ponds, membrane distillation, membrane distillation crystallization, electrodialysis and reverse electrodialysis, chemical precipitation, adsorption/desorption, eutectic freeze crystallization, pressure retarded osmosis and microbial desalination cell etc. are discussed. Although extraction of several materials from desalination brine is technically possible, it is currently expensive and largely restricts the commercialization. Last decade has witnessed an increased academic interest on this topic, however, the number of pilot-scale research has been very limited.