A ‘Smart’ approach on fluoride removal: detection in water sources and removal with biomass
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Date
2020-01
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Sokoine University of Agriculture
Abstract
Fluoride is one of the common minerals found in natural water, ingestion of which, at moderate concentration, is linked to good dental health. However, ingestion of higher concentrations of this mineral over a period is responsible for fluorosis, a disorder characterised by mottling of teeth and skeletal deformations. Therefore, the WHO sets the highest permissible level of this mineral in drinking water at 1.5 mg/L to limit its effect on public health. Consequently, a water source with fluoride concentration above this highest permissible level is regarded as unfit for human consumption, hence, requiring a treatment before consumption. As such, several studies have explored different low-cost methods to detect and remove this contaminant from drinking water. These include defluoridation and detection of fluoride by plant biomass and iron-based materials, respectively. These materials arc attractive because they have a potential for providing efficacious and cost-effective methods to deal with this water contaminant. In this thesis, the challenges delaying their field application (in detection and removal) of fluoride arc identified and suitable solutions are presented. Furthermore, the properties of iron that make it suitable for fluoride detection and removal enhancement in aqueous media arc presented.
A critical review of the studies published over the past three decades on water defluoridation by non-aciivated biomass reveals that, most studies explorc extensively only the defluoridation efficiency/capacily ofthese materials. This bias in studied properties is shown to be due to inadequacy in selection of study parameters, where, the defluoridation mechanisms are poorly studied. This could have resulted in the current poor understanding of their defluoridation mechanisms. Therefore, lessons from these studies were used to identify and propose the “must include” parameters to direct the future studies for better understanding of their defluoridation properties, especially, the defluoridation mechanisms. These are: effect of solution pH, point of zero charge and surface functional groups characterisation before and after material use.
For plant biomass ash, the major challenge associated with its application in water defluoridation was found to be related to media-induced contamination of the treated water, notorious being the elevation of the pH of the treated water. This challenge could have repelled many possible applications of this material in water treatment besides its great potentials as water treatment material. In this study, the Cyperus plants were successfully
Description
PhD-Thesis
Keywords
Fluoride Removal, Water Sources, Biomass