Globally, more than 90 million tonnes of waste textiles are generated each year, with China alone producing over 29 million tonnes annually. Faced with such a massive "mountain of clothes," landfilling takes up land and releases microplastics and greenhouse gases, while incineration may produce harmful smoke, making the recycling and reuse of waste textiles a key issue in the global circular economy.

Key Points

  • China generates over 29 million tonnes of waste textiles each year, with the global total exceeding 90 million tonnes.
  • Near-infrared spectroscopy combined with AI smart sorting systems has reached recognition accuracy of over 98%, processing thousands of used garments per hour.
  • Recycling technologies fall into three routes—mechanical, chemical, and biological—with the separation of blended materials as a common bottleneck.

Waste Textiles Are Not the Same as "Old Clothes"

The waste textiles handled by the industry fall into two major categories. One comes from factories, such as spinning waste, cutting scraps, and fabric edges, with clear composition and fewer impurities, making recycling relatively easier; the other comes from consumers, including discarded old clothes, old sheets, and old curtains, with complex sources often mixed with zippers, buttons, stains, and multiple fibers, making processing significantly harder. In particular, clothing today commonly uses blended structures such as "cotton + polyester" or "spandex + cotton," with different fibers entangled, making separation very difficult.

The First Step in Recycling Is Identifying Materials

In the past, workers judged fiber composition by "looking, touching, and burning"—cotton burns with a paper-like smell, while synthetics melt into balls. This method is inefficient, error-prone, and carries safety risks. Today the industry is turning to smart sorting: using near-infrared spectroscopy to "shine light" on different fibers, distinguishing material categories based on reflected spectral signals, and combining AI algorithms to automatically identify cotton, polyester, nylon, and other components. Some advanced systems have achieved recognition accuracy above 98%, processing thousands of used garments per hour.

Green Alternatives for Disinfection

Disinfection and sterilization before recycling are equally critical. High-temperature steam sterilization is effective but easily damages fibers, while chemical methods such as ethylene oxide may leave harmful residues. Supercritical carbon dioxide is a closely watched new path: under high pressure, carbon dioxide enters a special state between gas and liquid, penetrating inside fibers to kill bacteria and viruses, remove stains, and leave no chemical residue. Ozone disinfection and low-temperature plasma technology have also begun to be applied in this field.

Three Technology Routes: Mechanical, Chemical, and Biological

Mechanical recycling is the most traditional and widely used method, turning old clothes back into fibers through shredding, opening, and carding, then spinning them into mops, carpets, filling cotton, and even denim. It is low-cost and low-pollution, but fibers are broken and shortened, quality declines, and most products can only be downcycled. Some companies have developed gentler opening equipment to reduce damage, significantly improving recycled cotton quality.

Chemical recycling takes a different approach: polyester clothing is decomposed through chemical reactions into basic chemical monomers, then repolymerized into new polyester fibers, with product performance almost equivalent to virgin materials. Some companies have achieved a closed loop of "old clothes—recycled fibers—new clothes," and some sports and fashion brands use large amounts of recycled polyester. However, chemical recycling equipment is expensive, the process is complex, and separating blended materials remains a challenge.

Biological recycling is the most cutting-edge direction in recent years, using enzymes and microorganisms like "biological scissors" to precisely break down fibers. Cellulase can decompose cotton fibers into glucose, and certain special enzymes can break down PET polyester. Researchers have developed "plastic-eating" enzymes that can decompose plastics and polyester. Biological methods react gently and are more environmentally friendly, and are considered likely to transform textile recycling as a whole.

From Rags to Cars and Building Materials

The uses of recycled fibers have long gone beyond low-end rags, entering high-end sportswear, automotive soundproofing materials, building panels, and even oil drilling materials. Some companies use waste textiles to make automotive sound-absorbing cotton, while others add recycled fibers to concrete to improve crack resistance.

Links Still Needing Breakthroughs

Currently, waste textile recycling faces problems such as difficult separation of blended materials, high costs of green technologies, and inconsistent standards for recycled products. With advances in artificial intelligence, green chemistry, and biotechnology, old clothes recycling is moving toward a smarter, more environmentally friendly, and more efficient direction, and waste textiles are also being seen as an urban "fiber mine."

Source: Where Do Old Clothes Go? Unveiling the "Rebirth" Path of Waste Textiles · Originally published on 2026-09-24