Concentration of brines from RO desalination plants by natural evaporation

Development of desalination technologies in recent years, specially in the case of reverse osmosis process, enables now the massive production of water with a moderate cost, providing flexible solutions to different necessities within the fields of population supply, industry and agriculture. The great development of reverse osmosis (RO) technology has been a consequence of several factors such as energy consumption reduction and membrane cost decrease. Nevertheless, one of the problems of RO desalination plants is the generation of a concentrate effluent (brine) that must be properly managed. In the case of seawater desalination plants the brine is usually discharge to the sea since they are placed near it. However, in the case of brackish water desalination, brine management can be specially critic if the plants are placed far from the coast and far from any public channel or water-treatment plant where discharge the brine. The best option in this case is to concentrate the brine by reverse osmosis up to the technical limit of the process (around 70 g/L of salinity), and after that continue concentrating by means of evaporation until getting a solid waste that can be valued or directly managed by an authorised company. The aim of this work is to asses the viability of using natural evaporation (without heat supply) opposite to conventional evaporation for concentrating brines from brackish desalination plants. The main purpose of applying natural evaporation is to reduce the energy consumption of the treatment and the associated costs.