The investigation of nanofiltration membrane efficiencyto remove fluoride from water

One of the most important parameter in water quality is the amount of fluoride in water. Fluoride can cause bad effects on human body in high concentration. The most important of these is dental and skeletal fluorosis. According to the WHO guideline، fluoride concentration in drinking water should be limited in 1. 5 mg/l. According to the recent study، in some parts of Iran fluoride concentration is more than this standard. At present time، membrane technologies have a lot of advantages; therefore get improved in water industry. The aim of this study is investigation of membrane processes efficiency to product water with suitable quality of fluoride concentration in permeates. In this study، the efficiency of nanofiltaration membrane (NF33، 1812-50، FILMTEC) to remove fluoride from water was investigated. The effect of some chemical (initial amount of fluoride، sulfate and electrical conductivity (EC) and the effects of associated cation with fluoride ion) and physical (flow rate) parameters to remove fluoride were studied. Obtained results showed that the fluoride removal efficiency decreased with increasing in initial amounts of fluoride، sulfate and EC in feed water and increasing in flow rate. Moreover، this efficiency for CaF2 was higher than NaF. Compare with standard، fluoride concentration in all samples was in standard range and fluoride removal efficiency for this membrane was over 85%.