Electrodialysis reversal as an alternative treatment for producing drinking water from brackish river water: A case study in the dry season, northeastern Brazil

Abstract

Water scarcity has been a cause of concern throughout the world. Brazil, home of the largest freshwater reserve in the world, is no different, as it suffers recurring problems of scarcity and the uneven distribution of water reserves. This research evaluated the Electrodialysis Reversal (EDR) process applied to the treatment of brackish water from the Almada River Basin, southern Bahia, known as the Cocoa Region, in northeast Brazil. In periods of water scarcity, marine intrusion causes high levels of salinity in rivers and freshwater wells. Water collected directly from the Almada River, with high concentrations of sodium and chloride, 661.3 mg/L 1,091.9 mg/L respectively, and electrical conductivity about 2.98 mS/cm, was treated in pilot-scale EDR equipment. The treatment reduced conductivity by 70–80 %, especially removal of sodium and chloride, found in higher concentrations than those found in higher concentrations than those established in regulations for drinking water. After EDR treatment under two different values of applied electric current, the water reached levels suitable for consumption. The system operated at 80 % water recovery rate. The power consumption calculated for each treatment was 1.06 kWh or 2.6 kW/m3 and 0.66 kWh or 1.7 kW/m3. EDR proved to be an efficient alternative to guarantee the supply of drinking water during periods of severe drought.