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G. Gurumurthy

COIMBATORE, April 18

MEMBERS of the dyeing and bleaching units coming under the seven common effluent treatment plants (CETPs) in the hosiery town of Tirupur are facing the stick from the State Pollution Control Board (TNPCB) for failing to install the secondary effluent treatment facility.

The seven CETPs have been served with notices by the Board under Section 33A of the Water Act with a directive that if they failed to bring down the total dissolved solids (through segregation of salts used in dyeing) in treated effluents in line with the board's norms by May 31 next, action including closure of the units would be initiated against them, the Board has warned.

The TNPCB, which has found the TDS levels in the treated effluents released from these CETPs far above the permitted 2100 ppm, has been pressuring the CETPs to set up solar evaporators to facilitate segregation of the dye bath which is currently discharged along with the treated effluents.

The board has alleged that the dyeing units covered under the CETP arrangement are allowing discharge of the concentrated dye water along with the wash-water without removing the salts used in dye-fixation, thereby leading to ground water pollution.

The board has served notices on seven of the eight CETPs functioning in Tirupur, directing them to comply with the pollution treatment norms. The eight common treatment plants are attached to 288 dyeing units. These CETPs handle about 87 million litre of effluents every day, which is only put through the primary treatment process.

The dyeing units in Tirupur use approximately 300 to 350 tonnes of salt. But, in the absence of a system to recover these salts, the treated effluents discharged into the Noyal river undergo heavy sedimentation, affecting the ecology in the river system.

The Tirupur dyers have, however, sought more time from the board to implement its directive on segregation of dye concentrate and salt recovery. They have sought time to identify a suitable technology that would help them achieve a sustainable salt recovery process.

Though the solar evaporation technique would be relatively cheap to install, the Tirupur dyers point out that they are constrained by the availability of land for installing solar evaporators within the CETP premises. A 1,000-litre of dye-bath, they say, would need a 2,000 sq feet pan area for solar evaporation.

Besides the scarcity of land close to the CETP, evaporation in the rainy season would be difficult, they add.

The dyers estimate that it would cost a dyeing unit processing 1,000 kg of fabrics per day around Rs 10 lakh to instal a dye bath segregation system.

Though they could go in for multiple effect evaporators (MEE) (which operates on the system of distillation), the investment on such a system would be prohibitive. It was estimated that it would cost 40 paise to put one litre of dye-bath through the MEE system.

The third option open to the dyers was the use of reverse osmosis to achieve `0' discharge.

But here again, they were faced with the problem of handling the dye-concentrate.

They were awaiting the outcome of a pilot RO plant being put up in Tirupur by a dyeing house to recover `sodium sulphate'.

Since all these procedures may require more time, the Government should extend the deadline beyond May 31, they say.

Even while facing the TNPCB's tough talk, the Tirupur dyers have approached the Tamil Nadu Minister for Forest and Environment seeking a relaxation in the norms on the permissible levels of TDS in treated effluents.

The dyers have also asked the State Government to relax the two Government Orders that bar location of hazardous industries within specified distances of the river sources.

They fear that the two GOs, if implemented in letter and spirit, would create further problems for at least a few CETPs in the region.

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