Chennai Metrowater, as part of its efforts to become eco-friendly, is keen on reducing carbon dioxide emission from its new sewage treatment plants. For this purpose, it plans to commission a consultant for preparing the project concept and design note.

Metrowater is setting up three sewage treatment plants — at Nesapakkam with a capacity to treat 54 million litres a day; Perungudi (60 mld); and Koyambedu (120 mld). While the STPs in Perungudi and Nesapakkam are under construction, the project proposal of the Koyambedu facility is awaiting funds under the Jawaharlal Nehru National Urban Renewal Mission.

The water agency also plans to apply for carbon credit given to countries that emit less of green house gases under the ‘Clean Development Mechanism'. Officials of the Metrowater said the chosen consultancy firm is required to prepare the project concept with details such as technology to be adopted for reducing the carbon dioxide emissions, expected level of green house gases emission and environmental benefits of the project.

They must also obtain the host country approval from the Union Ministry of Environment and Forest, which is the authority designated by the United Nations Framework Convention on Climate Change, for the project. Besides getting the project registered with the UNFCCC for issue of emission reduction certificate, the consultant has to assist Metrowater in getting carbon credit validation, the officials said.

The targeted emission reduction is expected to be about 70,000 tonnes of carbon dioxide from the three new plants per year. Apart from saving electricity cost of Rs.2-Rs.3 crore per year, Metrowater would generate a revenue of Rs.4 crore per year by trading its credits with other countries.

The water agency has been generating electricity through biogas from sewage sludge to operate four of the existing STPs. “We have already submitted the project to earn carbon credit and it is being scrutinised for validation,” an official said.

Estimates are being prepared to provide facilities for gas-based power generation in the remaining five STPs, the official added.

The new STPs would also meet their power requirement from biogas. The consultant would have to complete the project in six months. While the construction of the plant in Perungudi would be finished by May next year, the upcoming STP at Nesapakkam would be completed in January 2012.

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