Development of a low cost household bone-char defluoridation filter

Abstract

Regular intake of drinking water containing fluoride above permissible levels (>1.5 mgl^-1) is responsible for dental and skeletal fluorosis. The objective of this study was to develop a low cost and efficient water defluoridation filter using local materials. The filter frame was made from Polyvinyl chloride pipe of 125 mm diameter and 1 m height, with a useful filtration volume of 9.55 l. The filtration layer consisted of a sequence of three strata: gravel, bone-char and sand, giving a total weight of 15 kg. Based on the concentration of fluoride in drinking water in parts of northern Cameroon, three different fluoride ion concentrations (10 mgl^-1, 20 mgl-1 and 30 mgl^-1) were prepared in the laboratory using distilled water and allowed to flow through the filter at the rate of 3.33 lh^-1. High fluoride uptake capacity was observed (94.8% to 99.1%), depicting the suitability of the filter in defluoridation. The constructed filter costed about 17 US$. Based on these results, the filter can be recommended as an appropriate technology to mitigate fluoride health hazards problems in low income families. Although the estimated replacement frequency of biochar was three months, further research is required to optimize the point of use system performances.

Keywords: Bone-char, water filter, fluoride.