Concentration effect and operational parameters on electrodialysis reversal efficiency applied for fluoride removal in groundwater

The increase in dental fluorosis in young people shows that the methods used to tackle the disease are ineffective. Typically, people around the world use groundwater for most activities, and this is the case of people especially in western Bahia, Brazil. In this region, aquifers can contain anomalous concentrations of fluoride. Thus, it is necessary to apply technologies to solve this problem by converting water resources rich in fluorides into drinking water. Consequently, in the present study, electrodialysis reversal (EDR) technology was used for defluoridation of natural water and synthetic solutions, simulating the fluoride concentration of natural water. Laboratory scale tests performed to treat synthetic samples with different fluoride concentrations, 1.5, 6.5, 9.1 and 13.0 mg F-/L, resulted in average fluoride removal of 90%. Additionally, one sample of natural water collected in the region of Cachoeira, city of Santana, Bahia, with an initial fluoride concentration of 7.49 mg (-)/L was treated using EDR. Results showed that EDR removed around 80% of the fluoride. The EDR technology reduced fluoride water contamination and adjusted the water to drinkable standards at a feasible cost, showing the viability of EDR for treating water.