Performance Evaluation of Semnan Active Bauxite Mine (Tash) in the Removal of Fluoride from Drinking Water: Case Study on Kuhbonan Water

Background: Although excess fluoride intake is detrimental for humans, but fluoride shortage may cause health problems. This study aimed on evaluation of removal of fluoride from aqueous solution using province Semnan (Tash) bauxite mine. Methods: The study was conducted in laboratory scale, from May to October 2013, on both synthetic and real water sample of Kuhbonan city in the Kerman environmental health engineering research center. The adsorbent was made from Bauxite obtained from Tash bauxite mine in Semnan province. Characterization of bauxite was studied by XRD and XRF. Synthetic samples contained fluoride were considered to determine the effect of pH, contact time, adsorbent dose and initial fluoride concentration on the efficiency of fluoride removal. Experiments on real water samples were done based of optimized adsorption condition. The kinetics and isotherm of the adsorption process were evaluated in order to better understanding the adsorption process. Fluoride measurement was carried out by SPADNS method. Data analysis was done by Excel software. Results: The maximum removal efficiency of fluoride, in synthetic sample, was 68.2% which was obtained at pH=7, contact time of 120 minutes and absorbent amount of 25g/L. The efficiency for real water sample was 61.67%, in optimized condition. Fluoride adsorption was best fitted with the Langmuir sorption isotherm equation (R2=0.991) and the second order synthetic model (R2=0.985). Conclusion: Bauxite from Tash mine could be initially applied for fluoride removal from groundwater samples with the efficiency of 61.67% which could be used as a low-cost and effective adsorbent.