Determination of fluoride concentration and that's zonation in the villages' drinking water resources of Poldasht County and presenting of practical methods for healthy water supply from fluoride viewpoint

Abstract

Introduction: Fluoride is an essential trace element for human health. But high concentration (more than 1.5 mg/l) of that can cause significant effects on human via potable water. The adverse effects generally include dental fluorosis and skeletal fluorosis depending on the concentration of fluoride in water and period of exposure. The main aim of this study was determination and zoning of fluoride concentration in the rural water resources of Poldasht County in West Azerbaijan province. The other objective of this research was the survey of practical ways of elimination of fluoride from polluted water resources in studied villages. Materials and methods: Water samples (92 samples) were taken from water sources of the villages (61 villages’ whit 23 water sources) in the studied area in all of seasons of year according to the standard method and carried to the laboratory. Fluoride concentration was determined with SPANDS method. Then the zoning of fluoride concentration was done by Arc GIS software. Then different methods of removal excessive fluoride such as bone charcoal, contact precipitation, Nalgonda, activated alumina, reverse osmosis, calcined clays and also managing approaches were surveyed by literature review and scientific reports. Finally by considering the economical, technical and the feasibility of different approaches, the activated alumina, reverse osmosis designed and surveyed in pilot scale. Results: The results of study indicated that the average concentration of fluoride was 3.80±2.54mg/L, 5.42±3.89mg/L, 2.64±2.07mg/L, 2.92±2.17mg/L respectably in spring, summer, autumn and winter (whit annually average 3.69±2.48). The maximum concentration determined 10.98mg/L in the summer in one of studied village water sources. The fluoride concentration in the 30 villages (whit population of 123332 or 37.32% of total population of area) was more than maximum recommended concentration of 1.5 mg/L. The results of survey of reverse osmosis indicated the average removal efficiency of 80.66% (inlet fluoride concentration 6 mg/l). While the average removal efficiency of activated alumina determined 94.25% (whit inlet fluoride concentration 12 mg/l). Conclusion: Due to high concentrations of fluoride in some potable water sources of studied villages the application of suitable measures to remove of the excessive fluoride from drinking water for prevention of bad health effects (such as dental fluorosis and skeletal fluorosis) strongly propose as described below respectively: water supply from new pure sources or dilution of polluted water, if those be possible in the area; using bottled water; application of reverse osmosis and activated alumina in point of use scale for removal of fluoride