The fashion industry is among the most unsustainable industries. When unsold or at the end of their useful lives, billions of pieces of clothing are simply discarded, ending up in landfill or incinerators. As per estimates made by consulting firm McKinsey and the World Economic Forum, the annual production of garments has at least doubled since 2000. This will significantly increase the amount of waste generated, consequently placing a growing burden on landfills. In total, around 85 per cent of textiles go into landfills each year.1

Textile recycling is one of the main solutions identified to tackle the issue of textile waste, alongside strategies such as waste reduction, garment lifetime extension, and the growth of the second-hand economy. Textiles for recycling can be of two types: Post-consumer, which comes from garments discarded by consumers, and Pre-consumer, from the manufacturing process of a product, including scrap created as a by-product from yarn and fabric manufacture.2

According to Ellen MacArthur Foundation, only a fraction of the garment undergoes recycling, with approximately 87 per cent of fibres used to make garments either burned or dumped in a landfill. In the United States as well as other nations like Ghana and Chile, millions of unsold and donated articles of clothing frequently end up in landfills each year. It is estimated that 40 per cent of all clothing bundles sent to Ghana ultimately end up in landfills.3

64 per cent of the textile waste produced is made of synthetic fibre, among which 54 per cent is polyester; the rest of the fibres are shared by cotton (24.7 per cent), man-made cellulosic fibres (7.2 per cent), wool (one per cent) and other animal fibres. Furthermore, there may be additional components such as buttons, zippers, linings, and coatings, each with their own distinct compositions. To produce recycled fibres of superior quality, it is necessary to segregate the textile waste into fractions consisting of pure materials.4

Available Textile Recycling Technologies

With growing awareness of the significant environmental impact of textiles, there has been a substantial surge in textile recycling in recent years. Consequently, there is a strong demand for the advancement of recycling technologies as they broadly apply to specific fibres or fibre blends. Various technologies are developed for recycling textiles based on mechanical, chemical, thermo-mechanical, thermo-chemical, and biochemical processes.5

1.   Chemical Recycling

Chemical fibre-to-fibre recycling requires pure fractions, making the development of effective separation processes a crucial factor in the advancement of textile recycling. It encompasses various processes where changes are made on the molecular level to textile fibres through chemical treatments to create recycled fibres. Numerous companies are actively advancing efforts to prevent textiles from ending up in landfills by offering recycling technologies.

Tyton Biosciences (US) uses water as a solvent to produce cellulosic pulp and polyester monomers from cotton polyester blended fabrics which are further used to make polyester or other materials. Worn Again Technologies takes non-reusable textiles and then cleans, extracts, separates, and regenerates virgin-quality polyester and cellulose from them, which is used to make rayon.6 Ambercycle’s technology produces PET polymers from blended textile waste that can be spun into polyester yarn.

2.  Mechanical Recycling

Textiles may also be recycled mechanically, where they are mechanically defibrated into fibres that can be spun into yarns for textile production, either with or without the addition of virgin fibres. Here the fibre composition of the textile waste becomes the same as the recycled fibre. However, the mechanical recycling of most textile materials often results in fibres of lower quality, leading to a process known as down cycling.7 However, a higher level of quality can be achieved by blending recycled shorter fibres with virgin fibres. They are mostly CO2 emission-friendly, with a 60 to 90 per cent reduction potential across all fibre types on spun fibre levels. Companies such as Purfi and Recover are among those exploring advanced mechanical recycling techniques.

3.  Thermo-Mechanical Recycling

Thermo-mechanical recycling uses a combination of heat and pressure to melt synthetic textiles like polyester and polyamide and recover polymers. However, this technology does not apply to natural fibres such as cotton or wool or MMCF (man-made cellulosic fibres) like viscose. It is notable for its relatively low energy consumption and the potential to minimise quality degradation compared to many other mechanical recycling methods. So far, the technology has mostly been proven effective for non-textile waste.8

4.  Thermo-Chemical Recycling

Thermo-chemical recycling is an open-loop technology that uses gasification to produce syngas through the partial oxidation reaction of polymers. This approach is compatible with all types of fibres. However, it is essential to note that this technology is not a closed-loop application for textiles. This technology aims to tackle textile waste comprehensively without restricting fibre composition. Beyond textile waste, this recycling method can potentially address the residual waste from other recycling processes (such as the non-cotton share of the MMCF process).

5.  Bio Recycling

Textile waste recycling can be achieved through a bioprocess incorporating enzymatic hydrolysis with ultrasound pre-treatment to transform composite materials into bio-products. The polyester component can be re-spun into reusable yarn, while the generated cellulosic powder can undergo further processing to produce soluble glucose. The Green Machine, developed by the Hong Kong Research Institute of Textiles and Apparel (HKRITA), is a viable commercial solution to separate cotton and polyester blended textile.9

Challenges

Recycling and other sustainable practices can transform textile waste into valuable resources. However, to enable large-scale recycling, minimising the mixing of fibres is crucial, as separating fibre blends during the recycling process is both costly and difficult. Companies often encounter challenges when expanding their fibre-to-fibre recycling operations by recycling blended textiles into new fabrics for clothing production. Presently, recycling technologies face five primary challenges:10

1.   Absence of commercially viable recycling methods for low-grade textile fractions

2.  Lack of mainstreamed, up-scaled processes and expertise to separate fibre types from mixed blends and composite structures

3.  High cost of recovery processes

4.  Prevalence of low-quality materials and blends dominating the recycling end-market

5.  The expensive logistics and limited availability of textile recycling facilities at both local and regional levels.

Furthermore, textile recycling techniques should successfully pass the Life Cycle Assessment (LCA) to ensure environmental sustainability. The LCA highlights an important aspect of the textile supply chain, specifically focusing on recycling techniques, transportation distances between textile recycling plants and waste collection areas, and energy consumption during transportation.11