Abstract
Abstract Fluoride concentration in drinking water higher than the recommended value imposes different health problems and there are advanced and chemical based defluoridation techniques, even if they are not feasible for developing countries and have limitations. Due to this, defluoridation by using locally available plants is one of the most efficient and sustainable options. Therefore, the current study was intended to investigate fluoride removal efficiency of Tulsi (Ocimum Sanctum) from water, which can be an alternative means to reduce the problem related to its high concentration. A laboratory-based experimental study was implemented by using potentiometric determination in Haramaya University. The leaves of Tulsi were collected, washed with tap water, rinsed with distilled water, and then dried at room temperature, crushed and sieved through a 500-μm stainless steel sieve. The experiments were conducted on water artificially fluoridated by anhydrous fluoride and natural water samples collected from deep well water sources from Adama and Harar town. Data was analyzed using Design of Expert (DOE) and Microsoft Excel. Twenty-nine runs for aqueous solution were conducted at different factor combinations and the optimum combinations were applied for natural water samples. The study depicts that the plant has an efficiency of removing 68.4% of fluoride from water. The best factor combinations to achieve this efficiency was 0.2 g/100 ml, 22.6 min, 5.7 and 6.6 mg/l, adsorbent dose, contact time, pH and initial concentration respectively. pH and initial concentration have a negative effect and adsorbent dose and contact time have a positive effect on removing fluoride from water. Hence, people living in fluorosis endemic areas can use the processed plant as a de-fluoridating agent to minimize adverse health effects.
Highlights
The presence of fluoride in drinking water in minute quantities is essential for normal mineralization of bones and formation of dental enamel
A recent study in the country shows that the mean level of fluoride in ground water is 6.03 mg/l and the pooled prevalence of dental fluorosis among residents in the rift valley area is 32% (Demelash et al 2019)
Because of its health impacts, the World Health Organization (WHO) cut the maximum value of fluoride concentration in water to be 1–1.5 mg/l and any water having higher than this level of fluoride needs to be treated with appropriate defluoridation techniques (WHO 2011)
Summary
The presence of fluoride in drinking water in minute quantities is essential for normal mineralization of bones and formation of dental enamel (reducing dental cavities, preventing tooth decay). It causes various effects if it is found in excessive concentration in drinking water (Dissanayake 1991; Wiem et al 2017; Yadav et al 2019). A recent study in the country shows that the mean level of fluoride in ground water is 6.03 mg/l and the pooled prevalence of dental fluorosis among residents in the rift valley area is 32% (Demelash et al 2019). Because of its health impacts, the World Health Organization (WHO) cut the maximum value of fluoride concentration in water to be 1–1.5 mg/l and any water having higher than this level of fluoride needs to be treated with appropriate defluoridation techniques (WHO 2011)
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