IIT-Delhi develops breakthrough method to recycle denim into high-quality garments

In a significant breakthrough, researchers from the Indian Institute of Technology-Delhi (IIT-Delhi) have developed a method to recycle denim waste into knitted garments without compromising on quality.

Led by Prof Abhijit Majumdar and Prof BS Butola of the Department of Textile and Fibre Engineering, the team successfully converted waste denim into yarn with minimal damage to fibre properties by optimising process conditions. The recycled yarn is then blended into knitted fabric using seamless whole-garment technology, resulting in garments containing 25 per cent to 75 per cent recycled yarn.

The team found that up to 50 per cent recycled yarn content could be used in knitted clothing without affecting the feel of the fabric. “To reduce the roughness of recycled yarns, a softening treatment is applied, ensuring the final product feels just like one made from virgin materials,” said Prof Majumdar. He added that while the study focused on denim waste, the method could be extended to other types of textile waste.

The research, published in the Journal of Cleaner Production, also included a life cycle assessment (LCA) to quantify environmental benefits in the Indian context. PhD scholar Satya Karmakar collected energy and material data from the Panipat textile recycling cluster. The LCA showed that recycling could mitigate 30-40 per cent of environmental impacts such as greenhouse gas emissions, acid rain and fossil fuel depletion. For ozone layer depletion, the reduction is as high as 60 per cent.

Using recycled fibres also reduces the demand for virgin cotton, thereby saving water, pesticides and fertilisers used in cotton cultivation — a process that alone contributes 24 per cent to global warming among all production stages.

“The team is now exploring the feasibility of recycling textile waste multiple times,” said Prof Butola.

India generates about 3.9 million tonnes of post-consumer textile waste annually, of which only 4 per cent is recycled. Most of this waste ends up in landfills due to variability in fibre blends and colours. Mechanical recycling also weakens fibre quality, making it challenging to produce high-quality garments from recycled textiles.