Accumulated mixed waste salt and bio sludge that are generated from effluent treatment of textile processing units are a major challenge to the textile processing sector in Tiruppur.
It is said that nearly 60,000 tonnes of mixed waste salt and about 50,000 tonnes of bio sludge lie piled up at the common and individual effluent treatment plants in the knitwear town.
Industry sources point out that about 300 operating textile processing units are connected to 18 common effluent treatment plants (CETPs) and these units recover 80 % of water used for processing. The CETPs reuse the water. The remaining 20 % of treated water goes through reverse osmosis membranes and evaporators and waste mixed salt, bio sludge, and chemical sludge are recovered. While the chemical sludge is sent to cement factories for use as co-processing material, bio sludge and waste salt are piled up at the units. Over the last 10 years, with the textile processing units in Truppur going in for zero liquid discharge, the salt and sludge that are generated in this process have turned out to be major challenges.
The sources point out that the CETPs are trying out different technologies to process the salt for reuse. They have partnered with various institutions to develop and try the solutions. “We need to look at cost effective methods and the government should support with initial investments,” says B. Murugabhoopathi, Chief Executive Officer of Dyers’ Association of Tiruppur.
Recently, the South India Textile Research Association partnered with MAK India and released salt-free dyeing technology. Meanwhile, the State government has signed a Memorandum of Understanding (MoU) with Incompressible Fluid Control System (IFCS) to reduce and reuse the salts from the waste. A technical team is expected to visit Tiruppur next week to study the technology implemented by IFCS at Rayapuram CETP.
T. Gopinath, Managing Director of IFCS, said the CETP, with 13 textile processing units connected to it, treats 40 lakh litres of effluent a day and 10 lakh litres is the reject water. A technology commissioned by the company in 2019 at a cost of nearly ₹ 12 crores at the CETP has reduced hazardous salt generation to just 5 % and the second grade sodium chloride recovered is consumed by the CETP.
“The technology has reduced generation of hazardous mixed salt by 95 %, brought down coal and energy consumption by 40%, and saved on the overall operating expenses of CETP by 40%,” he said.