Fluorides decontamination by means of Aluminum polychloride based commercial coagulant

The fluoride removal efficiency of the commercial product Actifluo (Brenntag) has been evaluated on both real industrial wastewater samples as well as on synthetic wastewaters. This study demonstrates that the treatment with the Aluminum polychloride (PAC) containing Actifluo, after a preliminary precipitation step with Ca(OH)2, improved the efficiency in the fluoride removal. This has been proved on wastewaters coming from four different companies of the south of Italy. In all the cases, the Actifluo treatment led to residual fluorides falling within the Italian law limits (fixed at 12 mg/L for sewage and 6 mg/L for surface waters). As a matter of fact, independently of the initial fluoride concentration, final values lower than 3 mg/L were obtained by treating wastewaters coming either from glass or dye factories. To determine whether pH and particle surface influenced the decontamination efficiency in surface water, synthetic wastewaters were analyzed by means of ζ-potential and Dynamic light scattering. The close relationship between pH and surface charge of the coagulant polymer present in the Actifluo was established and their effects on the fluoride removal efficiency assessed.