Fluoride removal from water and wastewater with a bach cylindrical electrode using electrocoagulation

[Display omitted] •An electrochemical reactor in a unique design was used.•97.6% Fluoride removal was obtained using Al cylindrical anode and rotating impeller cathode.•The recommended fluoride concentration of 1.2mg/L by WHO was obtained within 5min.•The effects of anions, cations and all ions together were determined. In this study, an electrochemical reactor with a unique design was used for defluoridation. A rotating impeller aluminium cathode and a cylindrical aluminium anode, which until now have not been employed for fluoride removal in the literature, were used, and various operating parameters, such as the electrode material (aluminium and iron), the current density (in the range of 0.5–2mA/cm2), the duration of electrolysis, the supporting electrolyte dosage (in the range of 0.01–0.03M Na2SO4), the initial pH (in the range of 4–8) and the presence of other ions(Ca2+, Mg2+, PO43-, SO42-), were examined to achieve optimal performance of the process. The experimental results revealed that the fluoride removal could be enhanced at pH 6, higher current density and higher electrocoagulation time using aluminium electrode. The presence of Ca2+ and Mg2+ ions also enhanced the removal efficiency while SO42- and PO43- ions effected adversely. The fluoride concentration was reduced from the initial value of 5.0–0.12mg/L, with a removal efficiency of 97.6% after 30min treatment at the current density of 2mA/cm2, pHi of 6 and presence of 0.01M Na2SO4. The required electrocoagulation time to reach the WHO-recommended fluoride limit of 1.2mg/L at 0.5mA/cm2 was 5min, with an energy consumption of 0.47kWh/m3. The obtained results show that this specially designed electrochemical reactor is an efficient alternative for the defluoridation of the water and the wastewater.