retention time, pH, temperature, voltage, number of aluminum plates between anode and cathode to assess the performance of this method. Results revealed that increase in hydraulic retention time by 5 min shows enhanced fluoride removal performance”. The concentration of fluoride reduces from 4 to 6 mg/L to less than 0.5 mg/L (Khatibikamal et al. 2010). According to the study of Emamjomeh and Sivakumar (2006) the performance of fluoride removal depends upon various parameters like current density, initial concentration of fluoride, flow rate of wastewater, and pH. The fluoride removal is directly related to aluminum F− hydroxide complex [AlnFm(OH)3n−m] formation during electrocoagulation (Emamjomeh et al. 2011).
2.6 Conclusion and Future Perspective
The contamination of fluoride in drinking water and groundwater has reached an alarming level already. This needs the immediate concern and involvement of people to alleviate this problem. Suitable remedial measures should be explored, meeting the geohydrological, sociocultural, ecopolitical, and environmental aspects of the area and also the people. Several defluoridation techniques have been employed when the level of fluoride increases in potable water. The fluoride concentration limit of potable water for any region is based on its dietary habits, annual daily temperature, nature, and level of exposure in the area. The remediation technology should consider the facts of availability of material, cost‐effectiveness, and level of fluoride removal, as well as technical complexity.
References
1 Alhababy, A.M. and Al, A.J. (2015). Groundwater quality assessment in Jazan region, Saudi Arabia. Current World Environment 10 (1): 22.
2 Al‐Hatim, H.Y., Alrajhi, D., and Al‐Rajab, A.J. (2015). Detection of pesticide residue in dams and well water in Jazan area, Saudi Arabia. American Journal of Environmental Sciences 11 (5): 358.
3 Ali, S., Thakur, S.K., Sarkar, A., and Shekhar, S. (2016). Worldwide contamination of water by fluoride. Environmental Chemistry Letters 14 (3): 291–315.
4 Ayoob, S. and Gupta, A.K. (2006). Fluoride in drinking water: a review on the status and stress effects. Critical Reviews in Environmental Science and Technology 36 (6): 433–487.
5 Barathi, M., Kumar, A.S.K., and Rajesh, N. (2019). Impact of fluoride in potable water–an outlook on the existing defluoridation strategies and the road ahead. Coordination Chemistry Reviews 387: 121–128.
6 Battaleb‐Looie, S. and Moore, F. (2010). A study of fluoride groundwater occurrence in Posht‐e‐Kooh‐e‐Dashtestan, South of Iran. World Applied Sciences Journal 8 (11): 1317–1321.
7 Bejaoui, I., Mnif, A., and Hamrouni, B. (2014). Performance of reverse osmosis and nanofiltration in the removal of fluoride from model water and metal packaging industrial effluent. Separation Science and Technology 49 (8): 1135–1145.
8 Bhagavan, S.V.B.K. and Raghu, V. (2005). Utility of check dams in dilution of fluoride concentration in ground water and the resultant analysis of blood serum and urine of villagers, Anantapur District, Andhra Pradesh, India. Environmental Geochemistry and Health 27 (1): 97–108.
9 Bhatnagar, A., Kumar, E., and Sillanpää, M. (2011). Fluoride removal from water by adsorption – a review. Chemical Engineering Journal 171 (3): 811–840.
10 Borah, J. and Saikia, D. (2011). Estimation of the concentration of fluoride in the ground water of Tinsukia town master plan area of the Tinsukia district, Assam, India. Archives of Applied Science Research 3 (3): 202–206.
11 Boyle, D.R. and Chagnon, M. (1995). An incidence of skeletal fluorosis associated with groundwaters of the maritime carboniferous basin, Gaspé region, Quebec, Canada. Environmental Geochemistry and Health 17 (1): 5–12.
12 Brindha, K. and Elango, L. (2011). Fluoride in Groundwater: Causes, Implications and Mitigation Measures. In: Fluoride Properties, Applications and Environmental Management (ed. S.D. Monroy), 111–136. New York: Nova Science Publishers.
13 Brunt, R., Vasak, L. and Griffioen, J., 2004. Fluoride in groundwater: Probability of occurrence of excessive concentration on global scale. International Groundwater Resources Assessment Centre (IGRAC), Utrecht, The Netherlands. 1–12.
14 Chae, G.T., Yun, S.T., Kim, K., and Mayer, B. (2006). Hydrogeochemistry of sodium‐bicarbonate type bedrock groundwater in the Pocheon spa area, South Korea: water–rock interaction and hydrologic mixing. Journal of Hydrology 321 (1–4): 326–343.
15 Chae, G.T., Yun, S.T., Mayer, B. et al. (2007). Fluorine geochemistry in bedrock groundwater of South Korea. Science of the Total Environment 385 (1–3): 272–283.
16 Chakraborti, D., Chanda, C.R., Samanta, G. et al. (2000). Fluorosis in Assam India. CurrSci 78: 1421–1423.
17 Chandrajith, R., Dissanayake, C.B., Ariyarathna, T. et al. (2011). Dose‐dependent Na and Ca in fluoride‐rich drinking water – another major cause of chronic renal failure in tropical arid regions. Science of the Total Environment 409 (4): 671–675.
18 Chandrawanshi, C.K. and Patel, K.S. (1999). Fluoride deposition in central India. Environmental Monitoring and Assessment 55 (2): 251–265.
19 Chatterjee, M.K. and Mohabey, N.K. (1998). Potential fluorosis problems around Chandidongri, Madhya Pradesh, India. Environmental Geochemistry and Health 20 (1): 1–4.
20 Chaudhry, M., Prabhakar, I., Gupta, B. et al. (2017). Prevalence of dental fluorosis among adolescents in schools of Greater Noida, Uttar Pradesh. Journal of Indian Association of Public Health Dentistry 15 (1): 36.
21 Choubisa, S.L. (2001). Endemic fluorosis in southern Rajasthan, India. Fluoride 34 (1): 61–70.
22 Cohen, D. and Conrad, H.M. (1998). 65,000 GPD fluoride removal membrane system in Lakeland, California, USA. Desalination 117 (1–3): 19–35.
23 Cronin, S.J., Manoharan, V., Hedley, M.J., and Loganathan, P. (2000). Fluoride: a review of its fate, bioavailability, and risks of fluorosis in grazed‐pasture systems in New Zealand. New Zealand Journal of Agricultural Research 43 (3): 295–321.
24 Dar, M.A., Sankar, K., and Dar, I.A. (2011). Fluorine contamination in groundwater: a major challenge. Environmental Monitoring and Assessment 173 (1–4): 955–968.
25 Das, D.K., Burman, G.K., and Kidwai, A.L. (1981). Chemical composition of monsoon rainwater over Bhopal, Madhya Pradesh (India) during 1977 and 1978. Indian Journal of Meteorology, Hydrology, and Geophysics (at present Mousam) 32 (3): 221–228.
26 Datta, P.S., Deb, D.L., and Tyagi, S.K. (1996). Stable isotope (18O) investigations on the processes controlling fluoride contamination of groundwater. Journal of Contaminant Hydrology 24 (1): 85–96.
27 Demeuse, M.T. (2009). Production and applications of hollow fibers. In: Handbook of Textile Fibre Structure (eds. S.J. Eichhorn, J.W.S. Hearle and T. Kikutani), 485–499. Woodhead Publishing.
28 DenBesten, P. and Li, W. (2011). Chronic fluoride toxicity: dental fluorosis. In: Fluoride and the Oral Environment, vol. 22 (ed. M.A.R. Buzalaf), 81–96. Karger Publishers.
29 Dubey, S., Agarwal, M., and Gupta, A.B. (2018). Recent developments in defluoridation of drinking water in India. In: Environmental Pollution (eds. V.P. Singh, S. Yadav and R.N. Yadava), 345–356. Singapore: Springer.
30 Edmunds, W.M. and Smedley, P.L. (2005). Fluoride in Natural Waters Essentials of Medical Geology (eds. B.J. Alloway and O. Selinus). Science and Education Publishing, Elsevier.
31 Emamjomeh, M.M. and Sivakumar, M. (2006). An empirical model for defluoridation by batch monopolar electrocoagulation/flotation (ECF) process. Journal of Hazardous Materials 131 (1–3): 118–125.
32 Emamjomeh, M.M., Sivakumar, M., and Varyani, A.S. (2011). Analysis and the understanding of fluoride removal mechanisms by an electrocoagulation/flotation (ECF) process. Desalination 275 (1–3): 102–106.
33 Emamjomeh, M.M., Safari Varyani, A., Alijani, M.H. et al. (2018). Effect of temperature and pressure on removal of fluoride from groundwater using