Ludhiana, Feb. 16 -- Even as the deadline to adopt zero liquid discharge (ZLD) technology expired in December, 19 scattered dyeing units in the city are yet to fully comply with the directions, raising questions over enforcement by the Punjab Pollution Control Board (PPCB).

The board had earlier directed all scattered dyeing units either to install ZLD systems or shut down/shift out of the city. The move came after it was found that untreated effluents from these units were being discharged into municipal sewer lines, eventually reaching sewage treatment plants (STPs) that are not designed to treat industrial wastewater. The partially treated waste then flows into the polluted Buddha Nullah.

While some progress has been reported on pape...