Two sewage treatment plants to replenish groundwater in lakes

CHENNAI: In a first of its kind initiative, Metro Water is setting up two tertiary plants at Nesapakkam and Perungudi to treat sewage water. These plants, with 10 MLD capacity each, will be instrumental in groundwater recharge as the treated water will be released into lakes. 

“We are going to adapt a circular water use concept. In sewage water, there will only be one per cent waste but we are replenishing it with 100 per cent fresh water. This way we are wasting 99 per cent water. If we are going to continue treating it this way, there will never be enough water no matter how much it rains,” said an official from Metro Water.

A study has been conducted at IIT and it was decided that sewage water will be stripped of smell and toxic pollutants through tertiary treatment with ultra filtration.  The treated water will then be let into the shallow wells dug close to waterbodies. Through this method groundwater levels within a radius of 2-3 km from the lakes will be recharged. This will depend on the soil type.

According to the official, water from Nesapakkam plant will be let into Porur lake and from Perungudi plant into Perungudi lake. The pilot project is being undertaken at the cost of `18 crore from the capital grant from the State government. The work is expected to get over by September.

In future, the existing method will be completely replaced with the new technology so that 550 MLD of sewage generated in the city can be treated and used to recharge waterbodies. The Metro Water department has also proposed tertiary treatment with ultra filtration plants of 260MLD across the city.