Removal and recovery of fluoride from wastewater by crystallization: effect of aluminum

The effect of aluminum on the treatment of fluorine-containing synthetic wastewater by crystallization was investigated. The results showed that the optimal conditions for fluoride removal were found at pH 7.2–10.5, and at an aluminum concentration of 80–700 mg/L. During operation of the fluidized bed reactor, the effluent fluoride concentration was 13–25 mg/L at an influent aluminum concentration of 80–150 mg/L. The recovered pellets matched well with the national standard of fluorspar in China (GB19321-88). It was feasible to recover calcium fluoride from fluorine and aluminum-containing wastewater by crystallization.