Consortium of experts to prepare a detailed project report

In four years’ time, nearly 60% of the sewage generated in the city may be recycled for industrial and indirect reuse. Chennai Metrowater is working with a consortium of academic institutions to prepare a detailed project report to use recycled water for recharging waterbodies.

To reduce freshwater demand and also tap the large volume of sewage as a resource for rejuvenation of lakes,

Metrowater has proposed to build waste water reclamation plants in Kodungaiyur, Koyambedu, Nesapakkam and Perungudi and convey a total of 260 million litres a day (mld) of reclaimed water to nearby lakes.

Pilot project

As a pilot project aimed at indirect use of reclaimed water, Metrowater will start the construction of a 10 mld tertiary treatment plant in Nesapakkam and Perungudi next week, and blend the recycled water into Porur and Perungudi lakes. Recycled water will be blended with freshwater in lakes at a ratio of 1:100 and again pumped to be treated and distributed through the drinking water supply network.

Officials of Metrowater said there was a delay in starting work as every component of the project, including volume, point of intake and design of the structures along the lakes, had to be approved by IIT-Madras. The project would be ready by January 2020. This infrastructure would be further expanded to generate 260 mld to recharge lakes.

The consortium, comprising experts from different academic institutions, will present recommendations for holistic planning and reuse of waste water. As a short term plan, it will suggest specific locations for treatment plants, sewage treatment technology and monitor the quality of reclaimed water and its impact on lakes. Treated water from four waste water reclamation plants will be released into lakes in Kovilambakkam, Narayanapuram, Keelkattalai and Ayanambakkam, among others. Decentralised water treatment plants will be constructed for indirect reuse of recycled water.

Upgrading technology

Tenders have been called for renovating existing sewage treatment plants to meet Central Pollution Control Board (CPCB) norms. The treatment technology will be upgraded to bring down total suspended solids and biochemical oxygen demand level to less than 10 mg/litre.

Officials said the 45-mld capacity tertiary treatment plant in Koyambedu is in the final stages of completion. This will soon supply the industrial belt in Sriperumbudur. Work has been completed on another 45-mld tertiary treatment plant in Kodungaiyur.