Chennai’s sewage treatment facilities are set to get a makeover to adhere to the revised norms of the Tamil Nadu Pollution Control Board. The water agency has called for consultancy services to prepare a detailed project report to rehabilitate sewage treatment plants.
Metrowater operates 12 sewage treatment plants (STP) across the city to treat sewage collected from 218 pumping stations and discharge in the nearby waterways.
At present, the city generates 560 million litres of sewage daily (mld), which are treated at plants located in five zones — Koyambedu, Nesapakkam, Kodungaiyur, Perungudi and Alandur.
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The facilities in Nesapakkam and Koyambedu are some of the oldest treatment plants established nearly 40 years ago and as the city expanded, more number of plants were added to cater to the expanding city. The STPs, including the small one in Villivakkam, have a total capacity to treat 769 mld, according to sources in the Metrowater.
In a bid to adhere to the treated effluent quality parameters as per the revised norms of the TNPCB, Metrowater proposes to repair and replace worn out components. For example, pH value has been revised from 5.5 to 9 to 6.5 to 9.
It has sought consultancy services to conduct prefeasibility study and assess the treatment units for their stability and suggest the kind of equipment to rehabilitate the STP.
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The quality of the sewage received must also be studied and a detailed project report must be prepared on modifications. The pipeline network conveying sewage to the STP and also discharging treated sewage into waterways must also be reviewed for repair.
Apart from providing a detailed cost estimate to take up project, the consultants would have to suggest alternate plans for waste water management during rehabilitation works.
It will ensure that they adhere to the revised norms of the Tamil Nadu Pollution Control Board