Treatment by adsorption on a dual-layer filter of hyperfluoridated brackish water from the Ndamatou borehole in Touba, Senegal
Abstract
Fluorine is a common component of natural water and plays an important role in many metabolic processes, when present in small quantities in the human body.
A concentration higher than 1.5 mg/L, as set by the World Health Organisation (WHO), can cause serious health problems, such as dental or bone disorders, Alzheimer’s disease and infertility.
Various methods have often been used to remove excess fluoride from water, but their cost and difficulty of application are barriers to accessibility for middle-income populations.
The aim of this study is to apply adsorption technology by superimposing two adsorbents, namely zircon and carbon made from filao litter, activated with calcium chloride. The treated samples were taken from the Ndamatou borehole in Touba (Senegal), and raw water characterisation has led to the conclusion that this water is brackish and hyperfluorinated. A 500 mL sample was passed through a double-layer filter with a contact time of 10 minutes, resulting in a 66.45% reduction in fluoride ions, from a concentration of 4.65 to 1.56 mg/L. Analysis of the other constituents of natural water showed reductions of 25.22% for bicarbonates. On the other hand, increases were noted for chlorides (104.28%), sulphates (65.89%), nitrates (46.87%), calcium (1141.76%), magnesium (323.80%), sodium (13.93%) and potassium (41.43%). These results demonstrate the mixed filter’s ability to retain certain pollutants and release others. In most cases, the concentrations obtained in the filtrate meet the standards or do not present a risk to human health. The increase in chlorides and calcium can be attributed to the activating agent.
Downloads
References
Garmes, H., Persin, F., Sandeaux, J., Pourcelly, G., & Mountadar, M. (2002). Defluoridation of groundwater by a hybrid process combining adsorption and Donnan dialysis. Desalination, 145(1–3), 287–291. https://doi.org/10.1016/S0011-9164(02)00424-1
Bhatnagar, A., Kumar, E., & Sillanpää, M. (2011). Fluoride removal from water by adsorption—A review. Chemical Engineering Journal, 171(3), 811–840. https://doi.org/10.1016/j.cej.2011.05.028
Kalavathy, S., & Giridhar, M. V. S. S. (2017). Low cost adsorbents for removal of fluoride from water—An overview. In: 3rd National Conference on Water, Environment, and Society (NCWES-2017), 210–213.
Alhassan, S. I., He, Y., Huang L., Wu, B., Yan, L., Deng, H., & Wang, H. (2020). A review on fluoride adsorption using modified bauxite: Surface modification and sorption mechanisms perspectives. Journal of Environmental Chemical Engineering, 8(6), 104532. https://doi.org/10.1016/j.jece.2020.104532
Mohan, D., Sharma, R., Singh, V. K., Steele, P., & Pittman, C. U., Jr. (2012). Fluoride removal from water using bio-char, a green waste, low-cost adsorbent: Equilibrium uptake and sorption dynamics modeling. Industrial & Engineering Chemistry Research, 51(2), 900–914. https://doi.org/10.1021/ie202189v
Ly, A., Coly, A. M., Camara, N., Ngom, B., Gassama, D., & Tamba, S. (2024). Use of zircon in the physicochemical process of defluorination of hyperfluorinated brackish water from the Diouroup borehole (Senegal). Science Journal of Chemistry, 12(4), 63–72. https://doi.org/10.11648/j.sjc.20241204.11
MINES SENEGAL. (2025, February 4). Phosphates en Afrique: Le Maroc et la Tunisie en tête. https://minesenegal.com/blog/2025/02/04/phosphates-en-afrique-le-maroc-et-la-tunisie-en-tete/
Onyango, M. S., & Matsuda, H. (2006). Chapter 1: Fluoride removal from water using adsorption technique. In A. Tressaud (Ed.), Fluorine and the environment (Vol. 2, pp. 1–48). Elsevier. https://doi.org/10.1016/S1872-0358(06)02001-X
Eddine, D. N., Salem, B., & Khaled, B. Des déchets agro-alimentaires : Cas des grignons d’olives.
Ibañez, E. F. (2002). Étude de la carbonisation et l'activation de précurseurs végétaux durs et mous (Thèse de doctorat). Éditeur non identifié.
Ghalmi, N., & Sifer, A. (2006). Essais d’adsorption du phénol et du cuivre sur charbon actif valorisé à base de grignon d’olives (Mémoire d’ingéniorat). Université de Boumerdès.
Salifu, A., Petrusevski, B., Ghebremichael, K., Buamah, R., & Amy, G. (2016). Defluoridation of groundwater using aluminum-coated bauxite: Optimization of synthesis process conditions and equilibrium study. Journal of Environmental Management, 181, 108–117. https://doi.org/10.1016/j.jenvman.2016.06.011
Zhou, S., Liu, Y., Wang, X., Zhang, Q., & Chen, J. (2025). A comprehensive review of fluoride removal using low-cost adsorbents for environmental and industrial applications. Environmental Surface Interfaces, 3, 146–162. https://doi.org/10.1016/j.esi.2025.04.002
Guèye, C. (2002). Touba: La capitale des mourides. KARTHALA.
Degrémont, G. (1972). Mémento technique de l’eau. Éditions Techniques Ingénieur.
Mamane, O. S., Zanguina, A., Daou, I., & Natatou, I. (2016). Préparation et caractérisation de charbons actifs à base de coques de noyaux de Balanites egyptiaca et de Zizyphus mauritiana. Journal de la Société Ouest-Africaine de Chimie, 41, 59-67.
Demirbas, A. (2004). Effect of initial moisture content on the yields of oily products from pyrolysis of biomass. Journal of Analytical and Applied Pyrolysis, 71(2), 803–815. https://doi.org/10.1016/j.jaap.2003.10.008
Gueye, M. (2015). Développement de charbon actif à partir de biomasses lignocellulosiques pour des applications dans le traitement de l’eau (PhD thesis, Fondation 2iE). Retrieved September 23, 2025, from https://agritrop.cirad.fr/579887
Ly, A. (2023). Contribution à la potabilisation des eaux saumâtres hyperfluorées de la région centre du Sénégal: Application au forage de Diouroup (Doctoral thesis, Université Iba Der Thiam de Thiès).
Labaier, Z., & Bouzidi, N. (2022). Élimination des ions fluorures en utilisant un charbon actif élaboré à partir des noyaux d’olives (Master’s thesis, Université Kasdi Merbah Ouargla). Retrieved September 22, 2025, from http://dspace.univ-ouargla.dz/jspui/handle/123456789/29625
Reffas, A. (2010). Étude de l’adsorption de colorants organiques (Rouge Nylosan et Bleu de Méthylène) sur des charbons actifs préparés à partir du marc de café (Doctoral thesis, Université de Savoie, Chambéry). Retrieved September 23, 2025, from https://theses.fr/2010CHAMS041
Pabyam, M. S., Gueye, M., Blin, J., & Some, E. (2009). Valorisation de résidus de biomasse en charbons actifs: Tests d’efficacité sur des bactéries et dérivés de pesticides. Sud-Sciences & Technologies. Retrieved September 23, 2025, from https://agritrop.cirad.fr/558482/
Omlin, J., & Chesaux, L. (2010). Évaluation de charbons actifs en poudre (CAP) pour l’élimination des micropolluants dans les eaux résiduaires urbaines (Master’s thesis, École Polytechnique Fédérale de Lausanne).
Organisation Mondiale de la Santé (OMS), Normes de l’OMS sur l’eau potable.
Rodier, J., Legube, B., & Merlet, N. (2009). L’analyse de l’eau: contrôle et interpretation [Water analysis: control and interpretation]. Dunod.
Microsoft Word - WSH_Guidelines_DrinkingWater_Quality-fr.doc. Consulté le: 24 septembre 2025. [En ligne]. Disponible sur: https://iris.who.int/server/api/core/bitstreams/b78fe338-e148-4e4a-90dc-c632f8e38ba1/content
El Achheb, A., Mania, J., & Mudry, J. (2001). Processus de salinisation des eaux souterraines dans le bassin Sahel-Doukkala (Maroc occidental). In First International Conference on Saltwater Intrusion and Coastal Aquifers – Monitoring, Modeling and Management (Essaouira, Morocco). Consulté le: 24 septembre 2025. [En ligne]. Disponible sur: https://www.researchgate.net/profile/Jacques-Noel-Mudry/publication/237779841_Processus_de_salinisation_des_eaux_souterraines_dans_le_bassin_Sahel_Doukkala_Maroc_occidental/links/00b7d52725f7486f42000000/Processus-de-salinisation-des-eaux-souterraines-dans-le-bassin-Sahel-Doukkala-Maroc-occidental.pdf
Organization Mondiale de la Santé (OMS) (2017). Directives de qualité pour l’eau de boisson. Quatrième édition, intégrant le premier additif.
FA_Bonvin_low.pdf. Consulté le: 22 septembre 2025. [En ligne]. Disponible sur: https://www.membratec.ch/data/documents/Presse/FR/FA_Bonvin_low.pdf
Valdez-Jiménez, L., Soria Fregozo, C., Miranda Beltrán, M. L., Gutiérrez Coronado, O., & Pérez Vega, M. I. (2011). Efectos del flúor sobre el sistema nervioso central. Neurología, 26(5), 297–300.
https://doi.org/10.1016/j.nrl.2010.10.008
Srimurali, M., Pragathi, A., & Karthikeyan, J. (1998). A study on removal of fluorides from drinking water by adsorption onto low-cost materials. Environmental Pollution, 99(2), 285–289. https://doi.org/10.1016/S0269-7491(97)00129-2
This work is licensed under a Creative Commons Attribution 4.0 International License.
