A little common sense

  • 14/11/1993

A little common sense EVERY day, Surat's 220 synthetic textile processing units and 15 dyestuff manufacturers release more than 35 million litres of largely untreated effluents into drains and creeks around the city. Surat is one of India's biggest synthetic textile centres, with a capacity to manufacture 10 million metres of fabric a day. And, as B C Deshpande of Colourtex, a dyestuff manufacturer, points out, "We have to be extra careful because our effluents are highly visible and evoke stronger criticism than the release of more toxic, but colourless effluents from other industries."

In July this year, a waste management group (WMG) was set up in Surat, comprising 70 industrialists and academicians. The group aimed at minimising waste generation and dispensing altogether with effluent treatment. Says Chittaranjan Desai, whose textile unit Paradise Prints was one of the first in Surat to implement waste minimisation, "Waste treatment mostly transfers pollutants from one medium to another -- from water to land. So end-treatment of wastes should be replaced by reducing pollutants." Desai's company has cut water consumption by at least 10 per cent and pared the consumption of chemicals and energy by 85 per cent and 40 per cent, respectively.

"I spent months examining each stage of textile processing, studying how waste could be reduced," says Desai, who was instrumental in setting up the WMG. WMG members share information and experience on waste minimisation and evaluate the properties of chemicals and dyes. "A database 'green list' and 'blacklist' of safe and harmful substances, respectively, will be drawn up," says WMG president R S Gandhi.

Waste minimisation in the textile industry can be achieved mainly through the reuse and recycling of water and chemicals and by chemical substitution. Textile units in Surat guzzle 10 million gallons of water every day, most of which is mixed with dyes and chemicals and simply drained out.

Says Gandhi, "There is ample scope for water optimisation." For instance, Bhavin Textiles has built storage tanks into which water that is otherwise drained out will flow. "This will save 67 per cent of the water consumed normally," says chief executive Dinesh Mehra. "Where 5,000 litres of water were released daily, we now release the same amount only once a week." Bhavin will also reuse effluents from its secondary treatment plant to wash screens and blankets. Mehra's team is now working on a system to ensure fabrics are washed continuously in baths without the water being drained out from the baths after each batch.

The Garden Vareli Mills at Surat also recently installed Rs 2-crore effluent water reuse plants. Says Garden's technical assistant, Tejash Naik, "About 80 per cent of the effluents discharged by our unit every hour are now reused." The unit also recycles the water used to cool jet dyeing machines.

At Paradise, six printing machines were wasting 43 per cent of the water used because it kept flowing even when the machines stopped. So the company introduced automation to stop the water flow with the machines. New jet dyeing machines, which need less than one-third of the normal water requirement, have also been installed.

"We save 1.1 million litres of water a month and Rs 79,000 annually with these measures," says Desai. His latest modification is reusing dyebath water, which he claims "conserves another 70,000 litres a month, reducing 90 per cent of the dyebath's chemical oxygen demand (COD) load, and cutting down on energy by 40 per cent and chemical use by 85 per cent."

Energy conservation is indispensably linked with waste minimisation. Paradise has reduced steadily its specific energy consumption (SEC) by 40 per cent. "Lines and machines have been insulated," explains Desai, "heat recovery units installed, boiler efficiency improved, pipelines of machines modified to eliminate energy wastage, steam condensate reused in water boilers and dye-bath water reused."

However, the industries have not yet embarked on large-scale machinery modifications that would follow changes in the production sequence itself. And, the industry is still wary of using substitutes. Says Mehra, "With some substitutes, the feel of the cloth may change and the prints become dull."

Desai dismisses these apprehensions. "There has been no change in the quality of fabric at Paradise," he asserts. "The substitution of harmful chemicals can most effectively reduce pollution at source." Paradise has selected substitutes on the basis of their biodegradability, aquatic toxicity, COD and BOD values and metal concentration (See table). He says the substitutes are also less expensive.

Less harmful
Warns M R Bhat of the environment engineering division of Sardar Vallabhai Patel Regional Engineering College in Surat, "Substitute chemicals could prove toxic in the long-run", but he concedes they are less harmful than those presently in use.

Other measures to reduce waste include inventory management to avoid dumping excess and out-of-date dyes and chemicals, and reducing dyestuff consumption by using computers to work out optimum and economical quantities. "The first step towards waste minimisation for any industry is a comprehensive waste audit," recommends Desai. "Machinery and process should be examined to identify the waste generators." Support by technicians and engineers is also essential.

The push towards reducing waste has come from depleting natural resources, stringent pollution norms and cost efficiency. Says Mehra, "The textile industry has no choice but to go in for waste minimisation." Overexploitation of groundwater has lowered the table from 18 metres to 55 metres. "The deeper we go, the more brackish and unfit for use the water becomes," says Mehra.

The Gujarat pollution control board's norms, which specify BOD and COD limits of 30 and 100 kg per month for discharges going into surface waters or public sewers, are also pushing the disgruntled textile industry to reduce its effluent load.

The most attractive aspect of waste minimisation is that investment is relatively negligible, unlike expensive effluent treatment processes. In addition, conservation of water, chemicals and energy improves cost efficiency. "Just common sense is required to streamline operations to cut down waste," points out Desai, "and a willingness to experiment with different raw materials and processes."

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