Unique way to desalinate water
villagers living in coastal areas need not travel long distances anymore just to get pure drinking water. Scientists at the Central Salt and Marine Chemicals Research Institute (csmcri), Gujarat, have developed a pump powered by oxen to purify brackish water. Pushpito Ghosh, director of csmcri, came up with the idea. Nagendra Pathak, a mechanical engineer at csmcri, along with his team, developed the system that works on the principle of reverse osmosis.
In standard osmosis, water molecules diffuse through a semi-permeable membrane from a region of low-salt concentration to an area having high levels of salt, thus equalising the concentration on either side. In reverse osmosis, saltwater is forced in at high pressure, due to which dissolved salt concentrates on one side of the membrane, leaving pure water in the other section of a container. A pump is required to force water through the membrane against osmotic pressure.
The procedure is simple, but is difficult for Indian villages lacking power to run the pump. Therefore, csmcri scientists decided to replace the motor power with animal energy. In their system, a pair of bullocks, while trudging slowly in circles, powers a gearbox that converts animal power into mechanical energy, which is then supplied to the pump.
The system can cater to the cooking and drinking water needs of about 1,000 villagers when operated for six to eight hours per day, by purifying 500 litres of brackish water in an hour. The scientists claim that it can also remove fluoride, arsenic, nitrate and heavy metals. The water is also free from bacteria. Moreover, the system does not cause pollution; it is free from mechanical hitches, and is self-supporting considering the meagre resources of villages.
Very soon, csmcri shall install two such units, one funded by the department of biotechnology and the other by the Pepsi Relief and Rehabilitation Trust, in earthquake affected villages of Kutch. The unit is expected to cost less than Rs two lakhs when produced on a mass-scale. Its operational cost is around three to four paise per litre -- 20-25 per cent lower than that of a unit running on diesel generator.
However, the system does have some drawbacks. The oxen will have to be trained to work according to the set procedure, and, as living beings, they are bound to get fatigued. Hence, after every two hours the pair of oxen has to be changed. Moreover, the animals are rather unpredictable and might stop working on their own accord.
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