Assessment of fluoride removal in a batch electro‒coagulation process

A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Master’s Degree in Environmental Science and Engineering of the Nelson Mandela African Institution of Science and TechnologyA presence of excessive amounts of fluoride than the prescribed standards has been reported in sources of domestic water supply around mount Meru slopes and other parts in Tanzania while efforts to remove the excessive fluoride was carried out using various technologies and materials. This study was perfomed to understand the fluoride removal effeciency of the electrocoagulation technique. It has been reported that in the electrocoagulation process, ions removal efficiency depends on the electrolysis time, voltage, pH and initial ions concentration applied. In this electrocoagulation process, experiments were carried out to examine its efficiency on removal of fluoride ions. The fluoride concentration tested ranged from 1.37 to 48 mg/L in both synthetic and natural waters. The voltage applied for the electrocoagulation process ranged from 0 to 50 V while maintaining an optimal pH of 4 to 9. Experimental results showed the removal efficiency of 90% with an optimal time of 30 minutes, at an applied voltage of 20 V and a pH of 6 at initial concentration of 29.5 mg/L at 300 ml. The method showed efficient removal of fluoride in water to achieve the allowable limits by the World Health Organization and Tanzania Bureau of Standards (1.5 mg/L). At this voltage (30 V), the process could be inferred to have the capability of treating the water and hence rendering such water safe for use as reported previously