The Tamil Nadu Pollution Control Board has detected two illegally operating dyeing units at Lakshmi Nagar and Angeripalayam areas during raids conducted over two days ending on Tuesday.

Both the units were found discharging effluents indiscriminately into the open in violation of the Madras High Court directives asking the dyeing units to adhere to the zero liquid discharge (ZLD) norms in the effluent treatment process.