Investigation On The Column Performance Of Water Defluoridation By Modified Fluorine Absorbent In A Fixed-bed

The fluorine is an important micronutrient for normal mineralization of bones and formation of dental enamel. Excess intake of fluoride would result in slow, progressive crippling scourge known as fluorosis. Various technologies for defluoridation based on the principle of adsorption, ion-exchange, precipitation-coagulation, and membrane separation process have been developed or are at the development stage. Among these methods, adsorption is probably the most wildly used in drinking water treatment because of its efficiency and economy.It has been substantiated that MgOP composite exhibits excellent performance for fluoride adsorption in batch experiment. For application of MgOP in field, fixed-bed column was selected due to simplicity in operations, cost-effective, as well as efficiency contact and separation from sorbent.In order to investigate the adsorption capacity of MgOP in column, breakthrough curves of fluoride on MgOP were measured by dynamic method under various experimental conditions and fitted by mathematical model such as the Thomas and Yan model, looking for theoretical support. The optimum operation parameters were found out. Experimental data confirmed a longer service time required to reach breakthrough when the bed mass was high, and when flow velocity was low. The adsorption capacity reached peak as the initial concentration was kept at 10 mg/L. Neutral solution and the present of HCO3- made a bad effect on defluoridation of MgOP in column while temperature showed little impact. What is more, the breakthrough behavior was found to fit better with the Yan Model in comparison of the Thomas Model, while the adsorption capacity predicted by the Thomas Model was closer to the experimental data.Furthermore, the stability of MgOP in colum was also taken into consideration. The level of magnesium ions transferred to the solution was monitored at about 1.5 mg/L under the level allowable. And only ten percent of descend in adsorption capacity was detected after 6 month storage.Above all, it can be confirmed that MgOP is a potential effective and safe sorbent for fluoride removal in a fixed-bed column.