Chennai Metrowater resumes pilot project on indirect use of reclaimed water

The plans include building tertiary wastewater treatment plants and modular water treatment plants, to add sources for Chennai’s growing water needs, officials said

Chennai Metrowater is building infrastructure to add more local sources for city water supply in places such as Retteri lake

As part of its approach towards a sustainable water supply alternative, Chennai Metrowater has accelerated work on its pilot projects to implement indirect use of reclaimed water in the city.

Sources at Metrowater said nearly 45% of the work to build tertiary wastewater treatment plants at Nesapakkam and Perungudi with a capacity of 10 million litres a day (10 mld) has been completed so far.

Work is also in progress to construct modular water treatment plants of 10 mld capacity each along Retteri, Ayanambakkam and Perumbakkam lakes. This is set to revive water bodies and add more buffer sources for Chennai’s growing water needs, officials said.

The pilot projects for indirect potable reuse of recycled wastewater are aimed at blending tertiary treated wastewater into Porur and Perungudi lakes also. Water drawn from the lakes would again be treated and distributed through the existing drinking water supply network.

Though the projects were slated to be completed by September, there would be a delay due to the lockdown period, officials said.

While the wait continues for imported materials such as treatment units and ultra-filtration membranes, the water agency plans to complete the civil work by mid-July. “Transportation of materials from other parts of the country is another challenge and supply is expected to resume in July,” an official said.

Of the total length of 24-km of pipelines to be laid between treatment facilities and lakes, pipelines have been laid for a distance of 11 km so far. “We are managing with 50% of the labour force as many workers have left for native places during the lockdown,” said an official.

These tertiary treatment facilities would have three processes of disinfection: pre-chlorination, ozonation and ultraviolet light disinfection. They have been developed based on designs approved by IIT Madras, officials added.

Once the pilot projects are implemented, plans are afoot to expand infrastructure for indirect use of reclaimed water to generate 260 mld and more water bodies, including Retteri, would be integrated with the network. The projects aimed at creating sustainable water resources and groundwater recharge.