Defluoridation of fluoride-rich groundwater in Mayo Tsanaga River Basin-Cameroon using locally produced bone char

Wilson Y Fantong,Clifford Ngappe,Ernest Chi Fru,Mathias F Fonteh,Hycinth S Banseka,Hubert Onibon,Etienne Yanne,Bertold D Dontsa Tsafack,Samuel N Ayonghe

doi:10.4314/jcas.v15i1.2

Wilson Y Fantong, Clifford Ngappe + Show 7 more

Open Access

https://doi.org/10.4314/jcas.v15i1.2

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Abstract

With fluoride-rich groundwater causing a climatic-dependent fluorosis in Mayo-Tsanaga River Basin, the overall objective of this study was to reduce fluoride concentrations in drinking water to acceptable levels thereby improving the resilience of the population to this climate change induced pathology. The specific objectives were to: (1) assess water chemistry in the study area to re-affirm the undesirable fluoride levels; (2) assess the impact of seasons on the concentrations of fluoride; (3) construct and evaluate the performance of a household bone char-based adsorption defluoridation filter. A combination of hydrogeochemical and engineering analyses demonstrated that the groundwater is predominantly Ca+Mg-HCO3 type, which contains as much as 6.73 mg/l of undesirable concentrations of geogenic fluoride. These concentrations increased with elevated pH, electrical conductivity and in the dry season, and were reduced to less than 0.2 mg/l when the groundwater was subjected to filtration through 300 g of 0.2-0.8 mm faction of charred cow bones in a home-based defluoridation filter. The bone char in the filter can effectively reduce fluoride concentration to less than 0.7 mg/l, which is the local threshold limit, without negative impact on the organoleptic (taste, color and odor) characteristics of drinking water. Compared with the commercially activated carbon, the bone char has an additional capacity of adsorbing fluoride at a rate of 4 mg/liter in 30 minutes, which indicates that with a defined saturation time, the bone char filter can protect the population against climate change-induced fluoride enrichment in drinking water.Keywords: Groundwater. geogenic fluoride. climate dependent fluorosis. bone char defluoridation. water chemistry

Highlights

A study by Fantong et al (2010), revealed that geogenic fluoride in groundwater resources in Mayo Tsanaga River Basin (MTRB) was affecting the oral/dental health of mostly children of about 500,000 residents in the basin. (Fig. 1)
Groundwater sampling, chemistry and effect of seasons on fluoride concentrations Sampling campaigns were conducted during the rainy and dry season months of September and April, respectively, for a total of 40 water samples; thirty-six (36) (Fig. 2b) from 18 villages, and four dry season samples from four boreholes in the Meri Sub Division based on their use, location and results obtained in the rainy season
The pH values showed acidic (5.9) to circumneutral (7.25), the lowest observed in Lycee Technique Meri, and the highest in Godola 1

Summary

Introduction

A study by Fantong et al (2010), revealed that geogenic fluoride in groundwater resources in Mayo Tsanaga River Basin (MTRB) was affecting the oral/dental health of mostly children of about 500,000 residents in the basin. (Fig. 1). Fantong et al (2010; 2013), suggested that the WHO upper limit of 1.5 mg/l fluoride in drinking water (WHO, 1994), should be adjusted to 0.7 mg/l for the Mayo Tsanaga River Basin, where consumption rate of groundwater is on the rise due to climate change-induced increase in atmospheric temperature. The defluoridation techniques can be broadly classified into the following four categories; adsorption, ionexchange, precipitation, and other techniques, which include electro chemical defluoridation and reverse osmosis (Piddennavar and Krishnappa, 2013). Among these categories the adsorption technique, which uses charred bones has been successfully employed to remove fluoride from fluoride-rich groundwater in Tanzania, Kenya, Uganda, Ethiopia, and South Africa (Dahi, 2016; Pindjou, 2015)

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