The fashion industry generates vast textile waste, which is often sent to landfills. Textile recycling, while promising, faces challenges like effective fibre separation. Diverse recycling technologies, including chemical and mechanical processes, are in development to tackle issues like low-grade recycling, and sustainability through Life Cycle Assessment.
The fashion business is one of the least environmentally friendly. Billions of pieces of clothes are simply discarded when they are unsold or have reached the end of their useful lives; they end up in landfills or incinerators. According to projections from the World Economic Forum and consulting company McKinsey, the annual manufacturing of clothing has increased by at least a factor of two since 2000. As a result, there will be a huge rise in the amount of waste produced, which will put more stress on landfills. In sum, 85% of textiles end up in landfills every year.
Along with tactics like waste reduction, extending the lifespan of clothing, and fostering the expansion of the second-hand economy, textile recycling is one of the primary options proposed to address the problem of textile waste. There are two categories of textiles that can be recycled: post-consumer textiles, which come from clothing that customers have discarded, and pre-consumer textiles, which come from a product manufacturing process and include trash made as a byproduct from yarn and fabric production.
Only a small portion of clothing is recycled, according to the Ellen MacArthur Foundation; 87% of the fibers used to produce clothing are either burned or disposed of in landfills. Millions of unsold and donated articles of clothes commonly wind up in landfills every year in the United States as well as other countries like Ghana and Chile. According to estimates, landfills receive 40% of all garment bundles donated to Ghana.
The majority of textile waste is composed of synthetic fiber, of which 54 percent is polyester. The other fibers are formed of cotton (24.7%), man-made cellulosic fibers (7.2%), wool (1%), and various animal fibers. Additionally, there could be other parts like zippers, linings, buttons, and coatings, each of which has a unique composition. Separating the textile waste into fractions of pure materials is important to manufacture recycled fibers of the highest quality.
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.
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. Ambercycle 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. 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.
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.
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:
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.
