Textile dyeing units in quandary over disposing of salt sludge

COIMBATORE: The Tirupur textile dyeing units are in a quandary over disposing off the salt sludge generated in common effluent treatment plants (CETP) in the district.

Over the last 10 years, nearly 50,000 tonnes of salt, a hazardous waste, have been accumulated in the 18 CETP’s across the district. They were also stored individually by the dyeing units.

“In the wake of an acute space crunch and rain lashing out frequently, it has become a herculean task for dyeing units to store the salt safely. As per pollution control norms, the salt sludge shouldn’t be dumped in the open or let into water bodies. Therefore, the government should take immediate steps to evolve a permanent solution for their safe disposal,” said S Murugasamy, general secretary of Dyers Association of Tirupur.

There are around 450 dyeing units in Tirupur and they generate up to 70 tonnes of salt sludge on a daily basis. The salt sludge has been accumulating since the inception of zero liquid discharge (ZLD) by Tirupur dyeing units in 2011.

Until then, the dyeing units gave away the lime sludge as a raw material to cement manufacturing firms. But, after the setting up of ZLD, the dyeing cluster has stopped using lime in the process of textile dyeing.

“There are private desalination firms with the required technology to dispose of the accumulated salt. However, the only glitch factor in them is that the cost runs unaffordably high as they charge up to Rs 6,000 to process one tonne of salt sludge. Left with no other option, the dyeing units give away the waste by paying an excess amount and dispose of a few tonnes, whenever they reach beyond the maximum capacity,” said S Gandhi Rajan, president of Dyers Association of Tirupur.

Though leather manufacturing firms in Ranipet have been utilising the salt sludge to process leather, it’s only in minimal quantities. The dyeing unit owners alleged that in states like Gujarat, the dyeing clusters release the salt sludge into the sea periodically, sometimes without even processing.

“It is however not advisable as TDS level of water may rise phenomenally and thereby affect aquatic organisms,” said N Karthikeyan, a dyer.