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ORIGINAL ARTICLE Table of Contents   
Year : 2008  |  Volume : 1  |  Issue : 2  |  Page : 56-58
Defluoridation of water by a one step modification of the Nalgonda technique


Kamineni Institute of Medical Sciences, Sreepuram, Narketpally, Nalgonda 508 254, Andhra Pradesh, India

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   Abstract 

Defluoridation of water by the Nalgonda technique is a commonly used household process in areas of endemic fluorosis in villages around Nalgonda (Andhra Pradesh, India). The aim of this paper was to modify the existing well-known procedure minimally and without much change in the cost to bring about a greater removal of fluoride. By doubling the concentrations of alum and lime, water fluoride levels fell significantly (p<0.001) in tap water and drinking water while pH levels and other inorganic factors remained unaffected.

Keywords: Defluoridation, Nalgonda technique

How to cite this article:
Suneetha N, Rupa K P, Sabitha V, Kumar K K, Mohanty S, Kanagasabapathy A S, Rao P. Defluoridation of water by a one step modification of the Nalgonda technique. Ann Trop Med Public Health 2008;1:56-8

How to cite this URL:
Suneetha N, Rupa K P, Sabitha V, Kumar K K, Mohanty S, Kanagasabapathy A S, Rao P. Defluoridation of water by a one step modification of the Nalgonda technique. Ann Trop Med Public Health [serial online] 2008 [cited 2014 Dec 19];1:56-8. Available from: http://www.atmph.org/text.asp?2008/1/2/56/50685

   Introduction Top


Defluoridation is the removal of excess fluoride from water. The National Environment Engineering Research Institute in Nagpur, India has evolved an economical and simple method of defluoridation, which is referred to as the Nalgonda technique. [1],[2],[3],[4] The Nalgonda technique has been repeatedly proven to be an economical and effective household defluoridation technique. [3],[4] In this commonly used technique, fluoride is precipitated using 500 mg/L of alum and 30 mg/L of lime. [1]

We have found that the removal of fluoride from potable water is not adequate when initial concentration of fluoride in the water is very high and the pH of the untreated water is alkaline. Moreover, different degrees of hardness of water require different concentrations of alum. [5] Therefore, we tried to modify the existing Nalgonda technique using the same materials in different concentrations. This preliminary study presents the effects of modification of the Nalgonda technique on the quality of tap water and drinking water.


   Materials and Methods Top


Water samples

Tap water (1 lit) samples were collected in plastic cans from 20 different villages in the Nalgonda district. This water originated from different bore wells that were collected in a common tank in the village. In some locations, the source of the drinking water was identical to the tap water pumped from bore wells. In other villages, separate wells were provided for drinking water; these drinking water samples were also analyzed.

Methods of defluoridation

Initially, varying concentrations of alum and lime were added to untreated water to find the combination that would decrease fluoride levels to a maximum extent. After the addition of lime and alum, water samples were allowed to stand for 30 minutes, 60 minutes, and 120 minutes to determine the shortest time for maximum flocculation [Table 1]. The weight of the sediment formed after 1 hour from 250 ml of water is also given in [Table 1]. Values are an average of results obtained from 5 water samples.

Analysis of water samples

Fluoride was analyzed using ion selective electrodes from Merck. Calcium levels in the water were analyzed by the ortho-cresolpthalein complexone method. [6] Magnesium was estimated by using the Magnon Complex method [7] and sodium and potassium were estimated using the flame photometer. [8] Chloride levels were measured by the Mercuric Thiocyanate method. [9] Iron was estimated using the Ferrozine method. [10] . Statistical analysis was done using Microsoft Excel (MS office, Windows 2000).


   Results and Discussion Top


All the water samples collected were found to be clear, colorless, and odorless, tasting brackish with an absence of suspended solids and visible impurities. The average pH of the tap water and the drinking water was found to be 7.4 ( 0.2).

Various combinations of alum and lime were used to defluorinate water samples [Table 1]. Combination I was the original Nalgonda technique, combinations II and III reduced fluoride levels significantly. However, the weight of the flocculated precipitate was greater with combination IV than with combinations II and III indicating that salts were precipitated to a greater extent. Hence, combination IV was used to defluorinate further samples [Table 1].

Both tap water and drinking water samples collected from 20 villages were treated with alum and lime as in combination IV and the results were presented in [Table 2] and [Table 3]. Using the original Nalgonda technique, fluoride levels in tap water decreased by 46.4% and fluoride levels in drinking water decreased by 59%. By using combination IV of alum and lime concentrations, fluoride levels decreased by 75% in tap water and 88.2% in drinking water. The precipitation of the salts that followed treatment by combination IV was 8.6 times the original Nalgonda technique in tap water and 1.3 times in drinking water. There was no significant difference between treated and untreated water samples for sodium, potassium, chloride, magnesium, and iron levels. The average pH was increased from 7.4 to 7.6 in tap water but decreased from 7.3 to 7.1 in drinking water, indicating that the composition of tap water and drinking water was different. The addition of extra lime led to a significant increase in calcium content of the water following treatment with combination IV (p<0.01).

To increase the removal of fluoride without excessively modifying the existing well-practiced Nalgonda method, we examined if altering the concentrations of readily available materials could remove excess fluoride from drinking water without affecting the quality of water. Our results show that doubling the concentrations of alum and lime results in a significant decrease in fluoride when compared to the existing Nalgonda technique [Table 1].

However, we recommend that the water defluoridated by combination IV can be used for domestic purposes only. Further studies are required to examine the implications of use of the modified method in decreasing fluoride in drinking water.

 
   References Top

1.Susheela AK, Das TK, Gupta IP, Tandon RK, Kacher SK, Ghosh P, et al. Fluoride ingestion and its correlation with gastro-intestinal discomfort. Fluoride 1992;25:7-12.  Back to cited text no. 1    
2.Phantumvanit P, Songpaisan Y, Moller IJ. A defluoridator for individual household: Appropriate technology. World Health Forum 1988;9:555-8.   Back to cited text no. 2    
3.Chinoy NJ, Narayana MV. Studies on fluorosis in Mehasana district of North Gujarat. Proc Zool Soc Calcutta 1992;45:157-61.  Back to cited text no. 3    
4.Chinoy NJ, Narayana MV, Sequeria E, Joshi SM, Barot JM, Purohit RM, et al. Studies on effects of fluoride in 36 villages of Mehasana district, North Gujarat. Fluoride 1992;25:101-10.  Back to cited text no. 4    
5.Susheela AK. Sound planning and implementation of fluoride and fluorosis mitigation programme in an endemic village. Proceedings: International workshop on fluoride in drinking water: Strategies, management and mitigation, Bhopal: 2001. p. 1-12.   Back to cited text no. 5    
6.Bowers GN Jr, Rains TC. Measurement of total calcium in biological fluids: Flame atomic absorption spectrometry. Methods Enzymol 1998;158:302-19.  Back to cited text no. 6    
7.Burcar PJ, Boyle AJ, Mosher RE. Spectrophotometric determination of magnesium in blood serum using Magnon. Clin Chem 1964;10:1028-38.  Back to cited text no. 7  [PUBMED]  [FULLTEXT]
8.National committee for clinical laboratory standards: Standarisation of sodium and potassium ion-selective electrode systems to the flame photometric reference method: Approved standard C 29 -A. Wayne, PA, National committee for clinical laboratory standards, 1995.  Back to cited text no. 8    
9.Schales O, Schales SS. A simple and accurate method for the determination of chloride in biological fluids. J Biol Chem 1941;140:879-84.  Back to cited text no. 9    
10.Rice EW, Fenner HE. Study of ICSH proposed reference method for serum iron assay: Obtaining optically clear filtrates and substitution of ferrozine. Clin Chem Acta 1974;53:391-3.   Back to cited text no. 10    

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Correspondence Address:
Pragna Rao
Kamineni Institute of Medical Sciences, Sreepuram, Narketpally, Nalgonda 508 254, Andhra Pradesh
India
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DOI: 10.4103/1755-6783.50685

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    Tables

  [Table 1], [Table 2], [Table 3]



 

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