Use of membrane technology for potable water production

Excess fluoride in drinking water is harmful for human health, so it is necessary to be removed. In this study the potential of a reverse osmosis (RO) membrane for defluoridation of underground water samples at different solute concentrations was studied. Because of the variation in feed water composition, its chemical properties, pH and operating conditions, effect of these parameters on the membrane separation process was studied. The results showed that pH, feed water composition, flow rate and pressure affect the membrane efficiency, and thus proper control of these factors is essential for successful operation. Optimum membrane properties and percentage rejection were determined for the RO system to minimize the overall cost of water treatment. The samples were collected from three villages in the Gurgaon district and treated at optimized conditions. The results indicate that RO membranes can be successfully used for the treatment of underground water to the desired purity level, as they remove up to 95% of fluoride present in water and also take care of other ions present in water.

1. pH has significant effect on the rejection ratio of fluoride. This behavior is due to the strong hydrogen bondings formed by the fluoride ion in acidic solution. 2. With an increase in operating pressure, the rejection rate increases. 3. The increase in flow rate results in higher flux and higher rejection, thus better permeate quality. 4. The RO process under study has proven to be a very efficient process for defluoridation of drinking water supplies beacuse it works at very low pressures and, in addition to fluoride, other inorganic pollutants are also removed without making any additional effort. No comparison has been carried out with other possible techniques.