Abstract

High fluoride concentrations in groundwater pose a health risk to people living in the Rift valley of Ethiopia and beyond. The Nalgonda and electrolytic defluoridation (EDF) fluoride treatment systems were developed and adapted in India for fluoride removal. A recent study evaluated twenty Nalgonda techniques that were implemented in the Rift valley of Ethiopia. A number of these systems were found to be non-functional or had never been utilized. The purpose of this study is to evaluate the performance of the Nalgonda technique and seek ways to enhance the fluoride uptake capacities.  Further, pilot testing of the EDF system was conducted in the Rift Valley of Ethiopia to evaluate its effectiveness at fluoride removal using natural groundwater in this setting. This study has shown that the performance of the Nalgonda system was significantly enhanced by adding aluminum hydro(oxide) (AO) and cow bone char powder into the existing Nalgonda systems; the initial fluoride concentration of 9.3 mg/L was lowered to 2.5 mg/L on average.  In addition to the increased effectiveness at fluoride removal, the addition of AO and cow bone char powder produced significantly less sludge compared to the existing Nalgonda system. The EDF system proved to be effective at removing the excess fluoride concentration in drinking water in the Rift Valley of Ethiopia; the initial fluoride concentration of 7.9 mg/L was lowered to 2.8 mg/L meeting the USEPA standard fluoride level of 4 mg/L. The pilot study showed Aluminum leaching into the treated water. Thus, further optimization of the electrode size, electrolysis time, and voltage/current used during the electrolysis process is needed to meet the WHO target treatment goal of 1.5 mg/L fluoride level and eliminate aluminum leaching as well. 

Key words: Electrolytic defluoridation, fluoride, Nalgonda, pilot-testing, sustainability.