Activated Alumina: Defluoridation of Water and Household Application – a Study

In fluoride endemic areas, especially small communities with staggered habitat, defluoridation of potable water supply is still a problem. In this respect household defluoridation techniques with attendant regeneration would be more appropriate and the present study is directed towards development of point-of-use domestic candletype filters for removal of fluoride from water employing activated alumina (AA) which is a proven material for defluoridation. Batch sorption kinetic studies employing activated alumina for sorptive removal of fluorides from water were conducted and observed to be dependent on various system parameters like contact time, pH, dose and ionic environment. Down-flow column studies further demonstrated the practical applicability and effectiveness of activated alumina in removing fluorides from an initial fluoride concentration of 5.0 mg FL -1 at a flow rate of 955 L/h/m 2 to the permissible limits of < 1.0 mg FL -1 . Experimental studies were also conducted to investigate the household applicability of activated alumina for removal of fluorides by filling the candles of domestic (candle) water filters with AA and found to be effective. Further, regeneration studies (cyclic adsorption – desorption studies) indicated that the spent AA may be regenerated and this would offset the overall cost of fluoride removal.