Household-level Fluoride reduction from drinking water using crushed fired clay – proof of concept

Abstract

Residents of Bunyangabu District in Uganda have reportedly suffered from cases of dental fluorosis due to consumption of water with high levels of Fluoride from Ntabago Stream. A household-level sand filter incorporating crushed fired clay as an adsorbent was designed for a household to reduce the Fluoride concentration in their drinking water from the natural raw water levels (2-3 mgF/L) to permissible, healthy levels (0.5-1.0 mg/L). Pieces of fired clay bricks were crushed, and particles of 150 µm to 300 µm in size were selectively obtained by sieving. Stream water was filtered through replicate model layered filter columns of the prepared clay, sand (fine sand of 150 µm-2 mm; coarse sand of 2-5 mm), and gravel (6-15 mm). It was found out that fired clay layers of 2.5 and 5 cm thick reduce the concentration of Fluoride in water by up to 74%, to less than 1.0 mg/L. This was deduced by evaluating Fluoride concentration in both the clay and water before and after filtration, using the SPADNS Colorimetric method. Use of crushed fired clay for reduction in Fluoride concentration in drinking water is the focus of this paper. Additional work will optimise filter design to improve overall water quality.