Chennai Metrowater will soon own the first-of-its-kind tertiary treatment plant in the State. The agency is in the process of finalising the design and treatment process of the facility that will reduce the amount of treated sewage let into waterways and also improve supply to industries.
The six-acre facility will be added to the existing sewage treatment plant in Koyambedu to treat the sewage another time to make it fit for industrial use.
The consultant, Engineers India Limited, is collecting data on the process to treat the sewage and also finalising the route to take the treated water from the plant to the industrial belt in Irungattukottai, Sriperumbudur and Oragadam.
Metrowater sources said the plant would reduce biochemical oxygen demand (BOD) and chemical oxygen demand in sewage to almost nil, a requisite for it to be used in industries. In the secondary treatment plants in Koyambedu, the BOD is reduced to 20 mg per litre from the nearly 350 mg/l found in the raw sewage.
The consultant is preparing a detailed project report for the plant a capacity to treat 45 million litres of sewage a day. “The design will be such that 60 mld of sewage can be treated in the future,” said an official.
The Koyambedu sewage treatment complex has two units that treat 94 mld. At present, the water agency supplies 37 mld to industrial units in Manali belt. Nearly Rs. 20 crore is generated through this. In order to meet the growing industrial demand, it was decided to recycle the water and provide it to the industries. The treated sewage will be conveyed through a 60 km pipeline to the industrial parks.
The consultant must also come up with project cost estimate and plans for funding pattern. The production cost of the treated water is estimated to be Rs.60 per kilo litre. The detailed project report and preparation of bids are expected to be completed in five months. Work on the tertiary treatment plant may start early next year.