Tuesday, 17 April 2007

Role of Panchayats in De-Fluoridation of Drinking Water Examples; Experiences by Alok Srivastava, Pankaj Kumar, Resource Persons, Jeevan, Mohanty, Tina Mathur, Ramya Gopalan

The query solicited members’ suggestions and experiences in developing models wherePanchayats could deliver fluoride-free water to its constituents in the context of severe fluoridecontamination in Bellary district. In response, members suggested various technical andinstitutional mitigation mechanisms to tackle the issue.Respondents pointed out that excess fluoride in ground water is reported in 177 districts of India,causing multidimensional health impacts including skeletal and dental fluorosis. Discussing thecauses of occurrence of excess fluoride in water, discussants noted that normally fluoride-richlayers exist at great depths, but in some cases such layers are also present close to the earth’ssurface. Fluoride enters into water by leaching when water adjacent to such layers is extracted.A long term solution to the problem, members felt, would be identifying and recharging freshwater zones.The group shared various short-term technical options for defluoridation such as Coagulation-precipitation, Ion-exchange, Adsorption, which have been tried so far in India with varyingdegree of success. Ion-exchange based solutions, such as activated alumina filters, have theproblems of replacing fluoride with other potentially harmful elements such as alumina, as well asof recharging the filters and safe disposal of fluoride-rich residues. Members reported that theNalgonda technique has fallen into disuse due to various reasons, notably lack of regularmaintenance and adequate training. In general, the problems with the above techniques werenarrow range of operation on different water parameters, regeneration of adsorbent, poorremoval efficiency at high fluoride concentration, sludge generation and safe disposal of residues.Among promising technologies for defluoridation members mentioned a membrane-basedtechnique developed by the Indian Institute of Technology, Delhi; a domestic defluoridation unitdeveloped by the Indian Institute of Science, Bangalore and some other Reverse Osmosismethods. Another simple but effective method of increasing supply of fresh potable water thatmembers suggested was roof-top rainwater harvesting, which has been effectively used in Karnataka and other places.

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