West Bengaluru to get water from TG Halli, ozonation to purify it

In a first-of-its-kind initiative in Karnataka, the Bangalore Water Supply and Sewerage Board (BWSSB) will use ozonation technology to purify water at the water treatment plant it is setting up at the TG Halli reservoir.

The BWSSB is in process of rejuvenating the reservoir to meet the drinking water requirements of some parts of Bengaluru. A major source of water for Bengaluru in the 1970s, the reservoir turned dry by 2012 and its rejuvenation will allow the BWSSB to pump 110 MLD of water to western Bengaluru.

Senior BWSSB officials said that the new technology is being used since officials feared that the water from Arkavathy, which flows into the TG Halli reservoir, may be contaminated owing to a few settlements which have come up around it.

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“We suspected that a small amount of sewage or such other contaminants may pose a threat to the quality of water since a few settlements have come up near Arkavathy River. Hence, we have decided to use ozonation technology,” said BWSSB Chairperson Jayaram N.

That apart, the flow of contaminants from the Peenya Industrial Area could also bring down the water quality, officials said.

During ozonation, ozone (O3) will be infused into the water with the help of a high-voltage current. This will clear the water of any bacteria or virus, thus disinfecting the water in the process.

“As a general practice, we chlorinate water to disinfect it. But here, water from Yettinahole could already contain chlorine, and the use of more chlorine to disinfect is not an ideal solution. Also, since we suspect higher levels of contamination, ozonation will be followed,” explained Rajiv K N, Chief Engineer, BWSSB.

Once the ozonation is completed, water will pass through a carbon filter which will remove the ozone present.

“Once it passes through the carbon filter, the water would be free of any contamination and can be supplied for houses. However, to avoid pipe contamination during supply to residences, we will add residual chlorine,” Rajiv added.

At present, ozonation is being practised only in a few cities, Delhi and Nashik, for example.

Rejuvenation by year-end

The rejuvenation of the reservoir, which started in March 2019, has missed multiple deadlines, the most recent one being September 2022. Officials now say the work will be completed by year-end.

“A majority of the work is completed. The machinery which had to arrive from various countries has been delivered and we are hoping to finish the work by the end of the year,” Jayaram said.

Senior BWSSB officials attributed the delay to labour shortage and problems with respect to the import of equipment owing to the pandemic.