Monetise chemical waste to enhance efficiency

A few years back, manufacturers in the industrial clusters of Vatva, Naroda and Odhav near Ahmedabad were facing problem of spent acid as companies were finding it difficult to individually store, handle or treat spent acid effectively. Spent acid is generated in chemical companies involved in manufacturing dyes, dye intermediates and other chemicals, where acid is used as raw materials. As a solution to this, industries association of the area formed Novel Spent Acid Management to help its member on no-profit, no-loss basis.
 
Novel Spent Acid Management, which collected and stored spent acid generating from the industrial clusters near Ahmedabad, supplied this spent acid (based on the quality) to the manufacturers of single super phosphate (SSP) and other chemicals as raw material. The remaining acid, which cannot be used, was neutralised after further segregation and gypsum produced during this process was sent to the cement manufacturer as raw material. Due to this facility, Gujarat Pollution Control Board claims that the incidences of the illegal discharge of the acid into the open environment have considerably decreased.
 
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This example shows how chemical industry waste can be put to good use with industry collaboration using simple technology.
 
Keep a tab on waste generation
In the words of late Barry Commoner, a global renowned environmental scientist and activist, “Environmental pollution is an incurable disease, it can only be prevented”. This is true especially in chemical industry, which is now relying on using E-factor (kgs waste per kg of desired product) to measure and minimise waste.
 
“How will manufacturers know if their chemical plants are green and sustainable if they have no way of measuring their sustainability? A major goal of green chemistry and sustainability is the minimisation of waste and the E factor (kgs waste per kg of desired product) is an excellent yardstick for quickly assessing how wasteful a chemical process is,” said Dr Roger A Sheldon, Professor of Biocatalysis & Organic Chemistry, Delft University of Technology, The Netherlands, who was recently in Mumbai to attend a Green Chemistry workshop.”
 
According to him, many major pharmaceutical companies, such as Pfizer and GSK, have calculated the E-factors of the processes used to manufacture all of their drugs and set goals for E-factors for the future. Similarly, many of the top chemical companies are taking steps to become greener by minimising waste formation and avoiding the use of toxic and/or hazardous substances.
 
“If you allow chemical waste to go untreated, then it creates problem. The first step in the waste management strategy is to reduce waste generation itself. We have been successful in improving efficiency of our manufacturing processes, thus leading to reduced wastage and effluents. This was achieved by optimising the production processes,” claimed Ashwin Shroff, Chairman & Managing Director, Excel Industries Ltd.
 
Reusing waste
There is no process which can give you 100% yield, thus there will always be wastages and by-products. Hence, it is important to find ways to recycle and reuse this waste in an optimal manner. “We are also working on converting chemical plant’s waste into energy by using anaerobic method,” informed Shroff.
 
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While treating waste discharge is mandatory requirement for chemical industry, using it to make useful products requires innovative thinking. For example, Heubach Colour, a leading pigment maker in India, has developed pharmaceutical aluminum hydroxide from green solid waste. “This process was indigenously developed and implemented by Heubach India and is a complete success, what is especially gratifying that this set a trend for solid waste reduction in the green pigment manufacturing industries who had to follow suit and this was Heubach's contribution to society as a Responsible Care company,” said Ravi Kapoor, Managing Director, Heubach Colour Pvt Ltd. From a potential 40,000 tonnes of waste per annum the project reduced this by 85% and made a pharma by-product.
 
According to a Tata Strategic Management Group (TSMG) report, the chemical industry is responsible for 20% of global effluents although it accounts for only 3% of the global chemicals market. Conventional synthetic chemistry based processes generate products with high E-factor. Hence, many chemical companies have now started exploring green chemistry based routes of synthesis to bring down wastage and optimise raw material consumption.