In an era where plastic pollution and fast fashion dominate environmental concerns, one company in Tamil Nadu, India, is demonstrating a powerful way to address both issues simultaneously. Shree Renga Polyester Pvt Ltd, founded by K. Sankar (also referred to as K. Sunar in some accounts) and now led in part by his son C. Tijo (or Senthil Sankar in related contexts), transforms discarded PET (polyethylene terephthalate) plastic bottles into high-quality polyester fibers and finished garments on a massive scale. Operating from Karur, the company processes around 1.5 million plastic bottles daily, converting them into approximately 25 metric tons of recycled polyester. This output supplies major global brands such as Adidas, Nike, Shein, Zara, and H&M, while the company also produces its own sustainable clothing line under the brand Ecoline.
Polyester remains one of the most widely used fabrics in the world, accounting for over half of all clothing material produced globally. However, only a small fraction—less than 15%—comes from recycled sources. Shree Renga’s approach not only diverts significant amounts of plastic waste from landfills but also reduces the environmental footprint of textile production. The process cuts greenhouse gas emissions by roughly 70% compared to manufacturing virgin polyester from petroleum-based raw materials.
The journey from waste bottle to wearable garment involves several carefully controlled stages, ensuring quality and efficiency while minimizing resource use.
Collection and Initial Preparation
The process begins with waste pickers and collection networks gathering used plastic bottles from urban and rural areas. These are delivered to sorting centers, where they are crushed and compressed into bales. Shree Renga purchases around 900 metric tons of this plastic waste each month, focusing primarily on PET bottles suitable for high-quality recycling.
Sorting and Cleaning at the Factory
Upon arrival at the facility, bottles undergo rigorous sorting. Non-PET components—such as polypropylene caps (often repurposed for items like battery cases), labels, and residual glue—are separated and sold or repurposed. Advanced sensors identify and remove contaminants like PVC, which could damage the melting process. Any remaining dirt or sand is collected and combined with ash to produce bricks used within the factory itself, promoting zero-waste principles.
Shredding, Washing, and Drying
The sorted bottles are mechanically shredded into small flakes, typically no larger than 14 mm. These flakes pass through a floatation tank, where denser PET sinks while lighter plastics float away and are removed. The PET flakes are then subjected to up to 10 thorough washes in a closed-loop water recycling system that reuses water efficiently, eliminating dirt, adhesives, and impurities. After washing, the flakes are dried and prepared for the next transformation.
Melting and Fiber Extrusion
Clean PET flakes are fed into an extruder, where they are melted at high temperatures. The molten material is often mixed with pigments using a dope-dyeing technique, which embeds color directly into the fibers. This method saves substantial water and energy compared to traditional post-production dyeing. The colored molten PET is forced through a spinneret—a precision metal plate with thousands of tiny holes—forming continuous thin filaments. As they emerge, the filaments cool, solidify, and are cleaned using high-frequency sound waves to remove any surface residue.
Stretching, Texturing, and Preparation
To enhance strength and performance, the filaments are stretched between rollers, aligning their molecular structure. They receive a light coating of starch-based lubricant to reduce static electricity, then undergo further stretching—often up to four times their original length. Heated rollers crimp the fibers to create a wavy texture, improving blendability with natural fibers like cotton. Finally, the fibers are cut to desired lengths, compressed into bales, and readied for shipment or further processing.
Yarn Spinning and Fabric Production
At connected facilities like Shree Renga Mills, the baled fibers are opened and carded into a thin web. This web is condensed into slivers—loose, rope-like strands—and refined for uniformity. The material then moves to spinning machines, where it is twisted into strong, consistent yarn wound onto bobbins.
Weaving, Cutting, and Garment Assembly
The yarn is woven into large fabric sheets on industrial looms. Quality inspections identify and remove any defects, with cut-out scraps recycled back into the system. Multiple fabric layers are stacked, marked with patterns, and precisely cut into garment pieces. Designs are applied through techniques like sublimation printing or heat transfers. The cut pieces are sewn together into finished apparel items, such as sportswear vests or casual wear. Under the Ecoline brand, the company produces around 400,000 garments annually, many made from 100% recycled polyester.
While Shree Renga’s model showcases the potential of circular economy practices in textiles, challenges persist. Recycled polyester can still shed microplastics during washing, and global plastic production continues to outpace recycling efforts. Nevertheless, operations like this highlight that sustainable fashion is achievable without sacrificing scale or quality, offering a blueprint for reducing waste and emissions in one of the world’s most resource-intensive industries.
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