Passing interim orders on a batch of writ petitions seeking to protect Ninnakaral lake from industrial effluents, a division bench of Justices S Manikumar and Subramonimum Prasad said, “TNPCB shall also submit details of treatment plants required to be set up by the new industrial units where effluent discharge process is involved.”

The court said the norms for establishing treatment plants for the already established industrial units and new units should be uniform in its considered opinion. “Merely because the industrial unit has been established earlier, it cannot be said that the said unit can escape from the vigour of pollution control laws,” the bench added.

The bench directed TNPCB to submit a report as to whether any orders have been issued to all the industrial units for undertaking necessary changes in managing effluents and steps taken in this regard, and posted the matter for further hearing to October 11.

Earlier, the bench recorded the submission of Commissioner Maraimalai Nagar Municipality that an oxidation pond was in use for the discharge of industrial sewage. The oxidation pond, a concrete structure, does not allow sewage to seep into the ground and there was no discharge into Ninnakarai lake, the official submitted.

However, the bench passed the directions to TNPCB after noting that since 1985 the position remains the same: the open oxidation pond was being used for industrial sewage, but the commissioner of Maraimalai Nagar Municipality has been denying the allegation of discharge of sewage into Ninnakarai lake.

The bench also recorded the commissioner’s submission that out of the 21 wards in Maraimalai Nagar Municipality spread out in an extent of 58.08 sq km, only 7 wards had underground sewage system. The collected sewage is treated using the extended aeration sludge process (EASP) in a sewage treatment plant (STP) with a capacity of 2 million litres per day and the discharged water meets the required TNPCB standards, the official said.