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Review Article STUDIES on DEFLUORIDATION- a CRITICAL REVIEW 1Dr Journal of Engineering Research and Studies E-ISSN0976-7916 Review Article STUDIES ON DEFLUORIDATION- A CRITICAL REVIEW 1Dr. Shrikant S. Patil 2DR. Nitin W. Ingole Address for Correspondence 1Director, Students W elfare, Sant Gadge Baba Amravati University, Amravati (Maharashtra) INDIA 2Professor in Civil Engineering, Prof Ram Meghe Institute of Technology and Research Badnera, Amravati (Maharashtra) INDIA. ABSTRACT Several materials including aluminium salts, calcined alumina, magnesia, lime, activated carbon sulphonated carbonaceous materials and ion exchange resins have been screened for their utility in defluoridation of water. Aluminium impregnated cation exchange resin and sulphonated carbonaceous materials prepared from coconut shell, paddy husk have been found to have a significant defluoridation capacity. Aluminium sulphate (Filter alum) solution is also found efficacious. On the basis of results extensive investigations, different researchers have developed a simple and economical domestic defluoridation processes. This paper represents the critical review of the past work on defluoridation studies by using conventional and unconventional materials and different methodologies such as ion exchange, precipitation, adsorption etc. KEYWORDS Defluoridation, ion exchange, precipitation, adsorption, and bone charcoal INTRODUCTION etc. The runoff carries available minerals due to Air, water and food are the three basic needs for the above activities and percolates with rainwater and survival of human beings. It is also very important joins the ground water. Some of the commonly that the drinking water should be safe and potable. In occurring general the public particularly in rural areas has no Constituents are calcium, magnesium, sodium, freedom of selection in respect of drinking water. In potassium, iron, manganese, arsenic, nitrate, common with other forms of life, man has a need for chlorides, fluoride bicarbonate etc. Presence of these water as an essential nutrient. Water is required for ions in excess of permissible limits, as prescribed by variety of function including regulation of the body IS 10500 & WHO in 1983, results in undesirable temperature, as a solvent and as a vehicle in the health effect. Among various ions present “Fluoride” transportation of other nutrients and waste products has physiological properties of the great interest and through the vascular system and through the inter and importance for human health and well beings. intracellular spaces. The requirement of water may Fluoride is a salt of an element called fluorine. vary from individual and in any one individual from Fluorine is the most highly reactive element of time to time under the influence of external stimuli halogen family. It has been estimated that fluorine is (Pande & Rao, 1978). Besides the several the seventeenth most abundant element constituting international and national conferences on water, the about 0.065% of the earth’s crust. It does not exist as problem for potable and safe water is yet to be a free element. Small amounts are found in seawater, solved. “Safe water and Sanitation for all” alongside bones and teeth. I exist in water mainly as fluoride “Health for all” is the new target for the year 2000 associated with monovalent cations such as NaF and (Killedar & Choube, 1996). The United Nation had KF are water soluble, while those forms with divalent proclaimed the 1980’s as the “International Drinking cations such as CaF 2 and PbF 2 are generally Water Supply and Sanitation Decade” (IDWSSD) insoluble. The fluoride forms many stable complexes during the UN water conference in Mar Del Planta, with ammonium and iron. Other compounds, which Argentina in 1977. The target of drinking water exist in acid solution, are mono and hexa- decade, 1981-1990 was to promote the provision of fluoroaluminate; and mono and hexa-fluoroferrate. clean water, may it come from a pressure water The simple free fluoride ion exists in alkaline supply. Water intended for human consumption solution (Choudhary & Kar, 1996). should be not only “Safe” but also wholesome water In India, fluoride commonly occurs in earth’s crust as is defined as the water that is: fluorspae (CaF 2), Appetite and rock phosphate and • free from pathogenic agents phosphorites. • free from harmful chemical substances Fluorspar: Fluorspar occurs in limestone, sandstone, • pleasant to taste and granite, quartz, calcite and berite. The major deposits • Usable for domestic purposes. of the above are found in nine states of India viz. Though surface water sources have fulfillde the water Gujrat, Rajasthan, Andhra Pradesh, Bihar, Himachal needs for a long time, presently with gradual Pradesh, Jammu & Kashmir, Madhya Pradesh, West extinction of surface water sources due to the Bengal and Tamilnadu. persistently increasing utilization, ground water Apatite and Rock Phosphate: The two major apatite sources are looked upon as the promising States in India are Bihar and Andhra Pradesh. Minor alternatives. Ground water often contains high occurrences have been reported from other states, viz. inorganic minerals under favourable conditions. Gujrat, Tamilnadu, Orissa, Rajasthan and West The conditions mainly are dissolution or weathering Bengal. of rocks and soils, dissolving of lime, gypsum and Phosphorites: The third major source of fluoride is other salt sources, mining activities, industrial and phosphorites-the sedimentary phosphate deposits. agricultural activities, geological formations of area The two regions in India with abundance of JERS/Vol. III/ Issue I/January-March, 2012/111-119 Journal of Engineering Research and Studies E-ISSN0976-7916 phosphorites are: North-West of India, comprising Besides rocks and soil, food items especially the States of Uttar Pradesh, Jammu & Kashmir, agricultural produce are heavily contaminates with Rajasthan and Tamilnadu. There are few major fluoride, which entrance into the human body occurrences in other state also. Dinesh Chand (2001), through various food items. Fluoride contents in reported that fluoride occurs significantly in rocks, different food items have been shown in the Table 2. soils, Plants and crops, drugs, industrial processes The fluoride leavel in industrial emissions and etc. A large group of minerals containing minor wastewater were exhibited in Table 3. fluorine was made up of the fluorocarbonates, Balusu K.R. and Nawalakhe W.G. (1979), state the fluorosulphates, fluorophosphates, fluoroarsenates occurrence of fluoride in excess of 1.5 mg/1 and and fluorocolumbates. The fluoride contains in same information is as shown in Table 4. mineral soils is as shown in Table1. Table 1. Fluoride Content in Minerals Soils Minerals Fluoride (mg/L) Meteorites 28-30 Dunite 12 Basalt 100 High Calcium 520 Granite - - - Alkali rocks 1200-8500 Shale 740 Sand stone 270 Deep seaa clays 1300 Deep sea carbonates 540 Table 2. Fluoride Content in Agricultural Crops and Other Edible Items Food Items Fluoride in mg/L Sengupta & Pal Lakadwala & Chari et al. Rajya Laxmi ( 1971 ) Punekar (1973) ( 1975 ) (1982 ) Wheat 4.60 2.59-3.30 -- -- Rice 5.90 3.27-14.03 2.90 -- Bajara -- 1.72-2.23 2.82 74.00 Soyabean 4.00 -- -- -- Red gram dal 3.70 2.34-4.84 -- -52.80 Cabbage 3.30 1.28-2.29 -- -- Lettuce 5.70 -- -- Tomato 3.40 1.00-2.08 0.33 -- Ladies Finger 4.00 2.20-3.62 1.74 -- Brinjal 1.20 1.62 1.24 -- Carrot 4.10 1.90-4.90 -- -- Potato 2.80 1.27-2.92 -- -- Onion 3.70 1.00-3.00 -- -- Banana 2.90 0.84-1.58 0.84 -- Grapes -- 0.84-1.72 -- -- Mango 3.70 0.80-1.80 -- -- Apple 5.70 0.24-0.52 -- -- Almond 4.00 -- -- -- Coconut 4.40 -- -- -- Groundnut 5.10 -- -- -- Tea(dry leaves) -- 39.80-68.59 -- -- Tea infusion -- 11.13-37.34 -- -- Aerated drinks -- 0.77-1.44 -- -- Mutton -- 3.00-5.00 -- -- Beef -- 4.00-5.00 -- -- Fishes 3.75 -- -- -- Table 3. Estimated total inorganic fluoride emission from majour industries in the United States Sources Emission Tons/Year Steel 40100 Ceramics 21200 Phosphet fertilizer and processsing Industry 18700 Aluminium Industry 16000 Combustion of coal 16000 Non Ferrous metal foundries 4000 Welding operations 27000 Table 4. Summarized information on the occurrence of excessive fluoride in ground water in India State No. of habitation with excess fluoride State No. of habitation with excess fluoride Andhra Pradesh 7548 Meghalaya 33 Bihar 12 Maharashtra 39 Gujrat 2376 Orrisa 1138 Karnataka 860 Punjab 700 Kerala 287 Rajasthan 16560 Madhya Pradesh 201 Tamilnadu 527 Haryana 334 Uttar Pradesh 1072 Himachal Pradesh 488 West Bengal 21 Delhi 46 JERS/Vol. III/ Issue I/January-March, 2012/111-119 Journal of Engineering Research and Studies E-ISSN0976-7916 There was a need for development of a broad concept The permissible limits of fluoride concentration in to tackle excess fluoride problem and its drinking water prescribed by various organizations implementation of strategy. The objective of are shown in Table 5. (Gopalkrishnan S. et al, 1991) supplying fluoride free water on regular basis may be Table 5. Permissible limit of fluoride in drinking achieved by adopting the following two options. In water prescribed by various organizations the first option the aquifers at different depths within Name of organization Permissible or in the vicinity of habitations were analyzed to limit of fluoride ion (mg/1) identify dependable safe sources or alternative safe World Health Organization 0.50 sources at economical depth and distance. In the (International standard for drinking second option, the fluoride water of the existing water) source was to be treated by using proven US Public Health Standard 0.8. technologies before supplying to the public (Chand The committee on public health Dinesh, 2001). Fluoride in excess of permissible limit engineering manual and code of 1.00 practice, Government of India. in water causes various kinds of fluorosis such as the Indian Council of Medical Research dental fluorosis, skeleton fluorosis and non-skeleton recommendations 1.00 manifestations. Chronic ignition of fluoride rich ISI recommendations 1.50 fodder and water in endemic areas leads to India is among 23 nations in the world, where development of fluorosis in animal (Patra R.C., fluoride contaminated ground water is creating 2000).
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