sir/mam myself Dharmaraj though i am doing a wonderful project which was purely based on the nalgonda technique of deflouridation.so i need the ppt/pdf which will includes all the armamentarium and the working model of the technique.

nalgonda technique ppt

The Nalgonda technique In the Nalgonda Technique two chemicals, alum (aluminium sulphate or kalium aluminium sulphate) and
lime (calcium oxide) are added to and rapidly mixed with the fluoride contaminated water. Induced by a subsequent gentle stirring, “cotton wool”-like flocs develop (aluminium hydroxides) and are subject to removal by simple settling. The main contents of the fluoride is removed along with the flocs, probably due to a combination of sorption and ion exchange with some of the produced hydroxide groups. The removal process, which is still not fully understood, has by some authors been designated as a co-precipitation. The Nalgonda Technique has been applied in India at different levels. On household scale it is introduced in buckets or drums and at community scale in fill and draw plants. For larger communities a waterworks-like flow
system is developed, where the various processes of mixing, flocculation and sedimentation are separated in different compartments (NEERI 1987). In the guidelines for household defluoridation published by NEERI in 1987, alum is to be added as a 10 per cent solution to a 40 litre bucket equipped with a tap. This was a modification of the previously described method,
where alum was added as tablets (Bulusu et al 1979). The amount of chemicals required to reach 1 respectively 2 mg/l fluoride are presented as a function of the fluoride concentration and the alkalinity of the raw water in a dosage design table, originally published by Nawlakhe etal. (1975). Unfortunately, the experiences gained in Tanzania and Denmark have shown that the usability of these design guidelines has two serious limitations: Many water sources have fluoride/alkalinity limits outside the ranges presented in the table. Furthermore, the recommended addition of lime, as 5 per cent of the added alum, have shown to result in pH-values in the treated water which are significantly different from what is optimum for the fluoride removal (Lagaude et al. 1988, Dahi et al. 1995).