Chennai Metrowater's ambitious pilot projects to add more local drinking water sources and also implement indirect use of reclaimed water are set to be commissioned in a phased manner from June.
In a bid to decentralise water storage and distribution, the water agency had proposed to draw water from the neighbourhood lakes in Retteri, Ayanambakkam and Perumbakkam. Nearly 35% of the construction work of the modular plants to treat the water has been completed so far, said officials of the Metrowater.
The objective of the ₹53 crore project is to revive the local water bodies and tap them as drinking water sources. However, release of raw sewage into the lakes continues to be a challenge for the source augmentation project.
“We have identified points where sewage is being released. We plan to have constructed wetlands with layer of canna plants and other aquatic plants depending on the quantum of sewage discharge. A combination of other waste water treatment methods may be adopted to remove suspended solids in the sewage,” said an official.
The water agency has roped in Care Earth Trust, a city-based voluntary organisation and a team that was involved in restoration of Jakkur lake in Bengaluru, to assess and rejuvenate lake ecology. They would help in designing the model for improving water quality.
A total of 30 million litres of water a day (mld) would be drawn from the lakes, treated in the modular plants and transmitted to the nearest distribution station. For instance, water from Ayanambakkam lake would be conveyed to the facility under construction in Mogappair, officials noted.
Work is also progressing on a full swing to create infrastructure for indirect use of recycled water. Nearly 35% of the work has been completed to build 10-mld tertiary treatment plants in Nesapakkam and Perungudi.
Sewage that is recycled at the plants would be blended with freshwater in Porur and Perungudi lakes at a ratio of 1:100. The water would again be pumped, treated and distributed through drinking water supply network.
Officials said it has been found that the flow in Adyar and Cooum rivers has reduced owing to overexploitation of resources in the neighbourhood. Reuse of treated sewage has an important role in groundwater recharge and restoring lakes.
“We are improvising the technology to ensure high standard of water quality as we are pioneering in the project. For instance, there are three stages of disinfection in the treatment process-use of sodium hypochlorite, ozonation and UV dose at different stages,” said an official.
There are also plans to expand the project of blending recycled water in Retteri, Ayanambakkam and Perumbakkam lakes for drinking water supply in the next phase .
