Design and construction of a community-based water defluoridation system

Abstract

Fluoride ion is a double-edged sword as inadequate consumption is related with dental caries while excessive intake results into dental, skeletal and soft tissue fluorisis which are known to be irreversible and have no cure. Residents of Ntabago village Bunyangabu district have been affected by the continuous ingestion of high levels of fluoride ions above 1.5 mg/L by WHO. The existing technology such as bone cha that is used is unhygienic and harbors bacteria hence causing other health risks. This led to a need of a multi-disciplinary study to find a solution to this problem. A defluoridation system which involves the use of aluminium sulphate as a coagulant (300 mg/L) and lime (50%) alum dosage as a pH adjustment chemical has been designed to remove the fluoride ions to a desired range. It also involves coagulation at 100 rpm for 60 sec, flocculation at 40 rpm for 30 min, sedimentation for 30 min and then filtration to remove the remaining suspended particles in the treated water. Parameters like pH of the solution was determined using a pH meter since the influence the removal of fluoride ions. The fluoride ion removal concentration was known using SPADNS method and the removal efficiency to a desired level of fluoride ions in the water. This project also gives the economic analysis of the defluoridation system and recommendations for future innovations.