"It is all domestic sewage"

Print edition : February 16, 2018

The bacterial oxidisation plant at the CETP in Arulpuram. Photo: S. Siva Saravanan

“IT is all completely domestic sewage” from Coimbatore and Tiruppur towns that is let into the Noyyal river, declared S. Nagarajan, president, Dyers’ Association of Tiruppur (DAT). No effluent is discharged into the Noyyal by the licensed textile dyeing industries in Tiruppur because the Common Effluent Treatment Plants (CETPs) and Indiviudal ETPs (IETPs) to which they are linked have achieved zero liquid discharge (ZLD), he said when Frontline met him at his office in Tiruppur on October 25, 2017.

A couple of managers of CETPs also claimed that “only domestic sewage” was being discharged into the Noyyal and not effluents from dyeing industries. Nagarajan, who is chairman and managing director, Divyar Garments Exports Private Limited, Arulpuram, Tiruppur, alleged that the Coimbatore Municipal Corporation discharged 250 million litres of sewage a day into the Noyyal.

Although there were three treatment plants at Ukkadam, Nanjundapuram and Ondipudur in Coimbatore city for treating sewage, their capacity was not enough to treat all the sewage generated in the Coimbatore Municipal Corporation area, he said. Tiruppur Municipal Corporation had 64 wards but only 16 had sewage treatment plants. “Sewage from the remaining 48 wards goes into the [Noyyal] river,” Nagarajan said. “The culprits are the government and the [municipal] corporations,” he added.

He denied the farmers’ claims that the abnormally high levels of total dissolved solids (TDS) was because of effluents let into the Noyyal by dyeing industries, and said that those areas already had a high level of TDS because of “the nature of the soil” there. “There is black soil, which contains a lot of salt. So the wells in those areas will always contain a TDS of 3,000 to 6,000 ppm. These are areas where there are no dyeing units.... Even on days when the dyeing units do not function, the TDS in the river is 2,000 ppm,” Nagarajan said.

There are 500 dyeing units in Tiruppur district and all of them are members of the DAT. There was the “possibility” of a few unlicensed units discharging effluents into the river, Nagarajan said. It was difficult to locate them because they “operated from houses, he said. Illegal units located inside Tiruppur town would be “meagre”. It cost 30 paise to treat one litre of effluent. If units did not treat the effluents and discharged them illegally, their cost would be less in the market. “They will give a stiff competition” to those who have achieved ZLD, he said. “Our association will not permit them to do that. We will tell the government that these units are doing illegal things,” Nagarajan said.

The Noyyal could be polluted by units making zips and buttons discharging their waste into the river. Industries printing fabrics and unlicensed dyeing units often washed their empty dyeing drums in the river, he added. Units in Coimbatore repairing and painting cars and other vehicles also discharged their waste into the river.

Nagarajan said the DAT had paid Rs.95.72 crore to the government for the loss of ecology caused by the dyeing units, for cleaning the Orathupalayam dam, as compensation to farmers and fine levied by the court. (The Supreme Court said the DAT should pay for the loss of ecology caused by them.)

About farmers’ allegations that dyeing units discharged effluents at night and during the rainy season into the Noyyal, Nagarajan said: “If it is let out for four days during the rains, what will be the big damage?”

Nagarajan explained that there were several processes involved in dyeing fabrics. The fabric had to be bleached, neutralised, dyed, then washed three times, the colours fixed and finally washed with water at 90° Celsius. This “hot wash” cleaned up the fabric. All this happens in a big dyeing vessel. To dye one kilogram of fabric, 50 litres of water containing dyeing chemicals were needed.

B. Gajendran, the manager of the Arulpuram CETP, said the 12 units affiliated to the CETP sent the effluents generated by them by pipelines to the CETP. Here, the effluents are treated and converted into reusable water, which is sent back to the units.

There is a cavernous storage and homogenisation tank, which is a bacterial oxidation plant. “We introduce the bacteria in the tank and they eat the chemicals, dyes and foreign materials,” said Gajendran. The “purified” effluents are then sent to clarifiers, where they are clarified. Then they are filtered using different types of filters. Then they undergo reverse osmosis and reusable water is obtained, he said.

T.S. Subramanian

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