I am waiting to get access to some fluoride testing kits so that I can visit C.K Pura again. I have been trying to find the chemicals needed for that, but in vain. Am still contacting people who might have them. I think I might just have found one!
Meanwhile, Mr.Vishwanath calmed me down by suggesting that I visit Professor Kesava Rao at IISc. He teaches in the Chemical Engineering department and works with treatment of drinking water, focusing on de-fluoridation. He was very kind and agreed to meet me right away. I spoke to him about what I was doing and asked him a few questions on effects of fluoride, de-fluoridation techniques and kits and he gave me a tour of his lab to look at projects that his students and himself have been working on.
Professor Kesava Rao
The first one was an M.E students thesis where he has built a device using a simple lunch box and a photo diode. A set of reagents are used to calibrate the resistance it offers which is then plotted on a graph to find out how much fluoride the sample contains. It is work in progress but it works! Something like this is easy to build as well as cost effective. Each box costs about Rs.250 (of course the chemicals and the gadgets apart) but would still work out lesser than testing the sample in a lab where they charge 1500-2000 rupees is what I was told. Here is a video of the professor explaining it to me.
Solar Still
This is another neat device that I was shown. It is a low-tech way of distilling water, powered by the heat of the sun. In a solar still, impure water is contained outside the collector, where it is evaporated by sunlight shining through the glass. The pure water vapor (and any other included volatile solvent) condenses on the cool inside surface and drips down off of the weighted low point, where it is collected in a bottle and removed. It distils and most impurities, I was told, including arsenic and fluorine. Volatile impurities also escape while it is heated up by the sun. It costs around Rs.850 to make a 0.5 sq ft/mt solar still. It has its advantages and disadvantages of course. The sun needs to be bright and out for this to work. It could also, at times be used to harvest rainwater and thus could even be a good idea to have in these villages since it requires low maintenance and cost. Here is a short clip of the one set up in the department terrace. They are soon going to take it to a fluoride affected area to test it and get some field data.
The last method was using activated Alumina (Aluminium Oxide)
The water is passed through a tube filled with activated alumina which absorbs the fluoride in the water to give out pure water. This powder though, gets saturated after a while and needs to be desaturated with some chemicals (which in turn become highly acidic). Thus it requires quite a bit of monitoring and maintenance once in a while. They are trying to reduce the costs so that this can be implemented. The water is stored in a plastic drum as seen in the first image and flows through the pipe, through the activated alumina (the powder in the second image) and comes out through the nozzle.
Sorry for the bad image quality! I wasn't aware that one could take videos inside the lab! Next time I'll make sure I take a better camera, these were shot on my cell phone.
This is a small part of a chart they have put up outside their lab on fluoride and flurosis and various methods of distillation that they are working on.
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