The lakes in Retteri, Ayanambakkam, Nanmangalam, Keelkattalai and Narayanapuram have been identified to be used as an alternative source of water supply to the city.
Officials of the Chennai Metropolitan Water Supply and Sewerage Board said once approved, infrastructure would be created to build tertiary treatment plants using ultrafiltration (TTUF) and convey reclaimed wastewater to the lakes to replenish the water table and promote indirect potable use of recycled water.
The World Bank-funded project would not only help decentralise treatment but ensure storage in lakes for freshwater availability throughout the year, the officials said.
The water board had commissioned 10 million litres a day (mld) capacity in TTUF plant in Nesapakkam last year as part of its ambitious project to implement indirect use of recycled water in the city.
Officials said the quantum of secondary treated water had been stepped up in phases for operation of the ₹47.24-crore TTUF plant. As of now, 4 to 6 million litres of wastewater is treated at the plant daily and conveyed to Porur lake. “We are testing and calibrating for the past few months to ensure quality of tertiary treated water,” said an official.
The water from the lake is treated and blended with existing distribution network and conveyed to areas such as Valasaravakkam, Alandur, Porur and Kumananchavadi.
Similarly, work is in full swing to complete the the 10-mld TTUF plant at Perungudi. The tertiary treated wastewater would be discharged into Perungudi lake and then supplied to surrounding localities after treatment. It was expected to be commissioned by April or May.
The way forward
Describing it as the way forward, L. Elango, professor, Department of Geology, Anna University, said recycled water could meet 30% of the city’s requirements by 2030. Citing his study on reliable sources for water management, he said the gap between demand and supply may go up by nearly 380 million litres daily by 2030 and reclaimed water would play a vital role in bridging the gap.
However, concerns of contamination in the waterbodies should be addressed to reduce treatment expenditure. Sewage outfalls in the waterbodies must be plugged to sustain the projects apart from sensitising the community to the issue, he added.
Published - January 09, 2023 08:33 pm IST
