The Optimum Conditions For Fluoride Removal From Drinking Water Using Nalgonda Method (Flocculation And Sedimentation)

Abstract

The Nalgonda method is one of the effective methods for fluoride removal, especially  with low and medium initial fluoride concentrations. In this research, the ideal conditions were found through studying the factors that affect the fluoride removal efficiency (initial fluoride concentration, pH, alum dose, mixing time for flocculation and coagulation processes, and the sedimentation time). The research results proved that initial fluoride concentration does not significantly effect the efficiency.As the removal efficiency amounted to (88%) for the initial fluoride concentration of (3) mg/L.While the removal efficiency was equal to (86%) for an the initial fluoride concentration of (10) mg/L. pH value was proved to be effective, as the removal efficiency was equal to (85%) when the (pH) value is equal to (7), while the removal decreased to (72%) and (63%) when the (pH) values were equal to (4) and (9) respectively.  Alum dose, time of mixing, and the time of sedimentation were also affecting on the removal efficiency. Best removal efficiency obtained at thetimesofmixing and flocculating equal to (1 min) and (5 min) respectively. Also it was found that it’s possible to get the same removal efficiency when increasing the period of rapid mixing to (3 min) and then directly move to the sedimentation process. Finally, the ideal sedimentation time has been set, best removal efficiency has been achieved a sedimentation time equal to (1 hour) and at the different measurement conditions. Keywords: Flouride removal, Drinking water, Nalgonda method, Flocculation, Sedimentation