This research work has been designed to remove the fluoride from aqueous solutions using alum by bench scale experiments. The defluoridating agent, which is easily available even in rural areas, has been selected. The known concentrations of fluoride solution were prepared. The removal of fluorides by the defluoridating agent was studied up to 4 hours for all the fluoride concentrations. The variations in the percentage removal and attainment of equilibrium were recorded. The solutions of 2, 4, 6, 8 and 10 mg/ L were prepared. Each Fluoride concentration was tested with 100, 200 and 300 mg/L of alum. The removal of fluoride increased at the rate of 10% per hour up to 55% by 4 h for 100 and 200 mg/L while it rose from 40 to 60% by 4 h equilibration time in 300 mg/L alum solution it reaches 60%. The difference of fluoride removal between 100 and 300 mg/L alum concentrations was only 5% i.e. 0.9 and 0.8 mg/L of fluoride remained after 4 h equilibration time. All the concentrations of defluoridating agent have successfully reduced the fluoride content in waters to permissible limits.
Deflouridation, Alum, Aqueous solutions, Equilibrium time, Batch tests