The Hindu : Mobile desalination plant under development

Online edition of India's National Newspaper
Sunday, Jan 25, 2004

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National

Mobile desalination plant under development

By T.S. Subramanian

This file picture shows Anil Kakodkar, Chairman, Atomic Energy Commission (extreme left), and B. Bhattacharjee, Director, Atomic Research Centre (centre), at the reverse osmosis section of the nuclear desalination plant at Kalpakkam. The plant was commissioned more than 18 months ago. - Photo: K. Gajendran

CHENNAI, JAN. 24. A mobile desalination plant that will be mounted on a barge, moving some metres off the coastline, is under development at the Bhabha Atomic Research Centre (BARC), Trombay. It can desalinate seawater or brackish water into potable water, and supply it to the villages on the shore. It can also be mounted on a trailer or a vehicle on land, and desalinate water at places where there is water scarcity.

Anil Kakodkar, Chairman, Atomic Energy Commission, told The Hindu: "This barge-mounted desalination plant is under development" at the BARC. "It will be ready by the end of the Tenth Plan, may be in 2006 or 2007. People are working out the engineering details," he said. It will produce 30 tonnes to 50 tonnes of drinking water a day.

"It can go on any platform. It can go by water route or land route. But the first idea is to put it on a barge," the AEC Chairman said. On the sea, it would float, depending on the draught. "The barge may be able to come within 10 metres of the shore," he said. But there should be a storage tank on the shore, which can be filled with the water desalinated. Similarly, if it is trailer-mounted, it can be parked near a storage tank that can be filled with fresh water. Pipes from the mobile desalination plant will fill the storage tanks with purified water.

In another important development, a massive desalination plant that will produce 45 lakh litres of potable water a day will start functioning in six months at Kalpakkam, 55 km from Chennai. "Work is progressing fast on that," he said. It would use multi-stage flash (MSF) technology. A big desalination plant, that produces 18 lakh litres of potable water a day, is already functioning at Kalpakkam for more than 18 months now. This uses reverse osmosis technology. The18 lakh litres of water are used at the Kalpakkam site, where there are several nuclear facilities.

When it becomes functional, the entire plant with a capacity of 63 lakh litres a day will be the world's largest seawater hybrid desalination plant to be coupled to a nuclear power station. These two plants are located adjacent to the Madras Atomic Power Station (MAPS), Kalpakkam, which has two reactors generating electricity. These two desalination plants are linked to the MAPS, and have been built by the Desalination Division, BARC, Trombay.

In the MSF process, which the 45-lakh litre a day desalination plant will use, seawater is evaporated by using steam. It will make use of the low-pressure steam obtained from the turbines of the MAPS. This evaporated seawater at above atmospheric pressure is led to a lower pressure unit, which results in the release of vapour that is condensed to get potable water. In the reverse osmosis process, saline water or effluent water is forced through a semi-permeable membrane in excess of osmotic pressure and potable water is produced. The membrane, made of polymeric material, has big and small pores. Big tanks filled with layers of pebble, sand and activated carbon remove suspended salt particles from the water.

Dr. Kakodkar added, "We have a big desalination plant at Kalpakkam. We want to grow on that experience."

From 1975, the BARC, the premier Research and Development centre of the Department of Atomic Energy, has erected a number of desalination plants in Andhra Pradesh, Gujarat, Rajasthan, Port Blair and on the BARC campus itself at Trombay.

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