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Tuesday, June 13, 2006

MIT students develop low cost water purifier

MANIPAL: Civil engineering students of Manipal Institute of Technology have developed a low cost filter to purify water.

The filter developed by the students as part of their project under MAHE-Philips BOP programme, is designed using locally available materials such as coconut shell, charcoal, sand and pebbles to remove the excess iron from water and make it fit for drinking and other domestic purposes.

"In well water, iron is usually found in its ferrous state. The water is clear when freshly drawn, but once exposed to air, the iron will oxidize it. It will be seen as red discolouration of water and forms insoluble rust particles.

Percentage of excess iron in well water of Udupi taluk is high ranging from 10.5 to 23.34 mg/litre against the Indian Standards Institution’s limitation of 0.3 to 1.0 mg/litre. With this concern, we decided to develop this filter," said Dr Narayan Shenoy, professor, Civil Engineering Department, MIT, Manipal.

The filter consists of three units- aeration, activated carbon and sand. These units are assembled inside a drum of about three feet height and eight inch diameter of non-corrosive material.

The drum consists of metallic mesh fixed in the bottom just six inches above the outlet. Sand unit placed above the mesh consists of three inch thick layer of pebbles and its size varies from 2.36 mm to 40 mm at the bottom followed by 3 inches of coarse sand of grade I (size

Sand is the main component of the purifying system, which has the highest iron removal capacity among all the three units. "It strains out suspended matter and other impurities," Shenoy said.

Above the sand layer there is a six-inch layer of activated carbon. This is obtained by burning coconut shells, which is later, treated with calcium carbonate solution. The obtained carbon is crushed to 5 mm size and is washed thoroughly. This layer is provided to remove undesirable odour, taste, turbidity etc.

Water enters the filter from an overhead tank to the aeration unit and gets uniformly sprinkled over the activated carbon unit. "The main objective of providing the aeration unit is to remove the iron load on the filter. Its inclusion aids in increasing the iron removal capacity of the filter, uniformly distributing water over the filter and decreasing the maintenance required for the filter.

Water, from the activated carbon unit, moves to the sand unit. In each unit, varying degree of iron removal is affected, as well as general purification", Shenoy added.

The total fabrication cost of the filter is around Rs 2,000. The Rotary Club, Udupi-Manipal has taken the initiative to transfer this technology to rural areas.

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