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Experts suggest ways to purify water at home

K.S. Sudhi

Contamination of Periyar waters

KOCHI: As muddy water from the Periyar flows through the pipelines here, water quality experts have come up with a "do-it-yourself" action plan for making the water supplied at homes potable.

Experts suggest mixing of water with alum, passing of electric current through water and the traditional three-layer filtering technique for consumers to purify water, without waiting for the intervention of the authorities.

Mixing of potash alum (a combination of potassium sulphate and aluminium sulphate) in water collected at homes has been suggested by E.J. James, executive director of the Centre for Water Resources Development and Management, Kozhikode, and M.K. Mukundan, head of the quality assurance and management division of the Central Institute of Fisheries Technology, Kochi.

Alum should be added at the rate of .01 g a litre and stirred. Leave the water for some time for the impurities to settle down. Once that happens, the water can be safely transferred to other containers, they say.

Use of alum for water treatment is safe and will not cause any health hazards, as it helps to precipitate the impurities and settle them down. During the process, only a small fragment of the chemical will be left in the water, Dr. Mukundan says.

Alum can be purchased from shops dealing in chemicals. While these shops may charge around Rs. 100 for half a kg, you may get it much cheaper if bought in bulk from companies selling them, says a dealer. Bulk quantities can be had from chemical manufacturing units in the industrial belt of the district.

Dr. Mukundan suggests discharge of electricity through water — a technology that has been experimentally proven in fish processing plants to treat effluents — for clearing impurities. Power generated by a car battery or its equivalent will be sufficient for the process, he says.

Dip two diodes connected to the power source for a few minutes in the water and allow the sediments to settle. The electric charge in the impurities will be discharged and they will be forced to form big particles and settle down, he explains.

Dr. James suggests the application of the traditional wisdom of the three-layer water filtering system.

This system will have clean sand on the bottom layer followed by another layer of charcoal. Clean sand with bigger grain size will be used in the upper layer. Water filtered through the system will be potable and the method is widely used for filtering in rainwater harvesting units.

Bhadran, former Government analyst of the Regional Analytical Laboratory, suggests using a combination of bleaching powder and slaked lime for purifying water. For treating 4,000 litres of water, 10 g of bleaching powder and 125 g of slaked lime should be added and the combination should be given a contact time of two hours. Filtering of water using thick cloth is also advisable. Boil the filtered water for drinking purposes, he suggests.

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