UNDERSTANDING CURRENT APPROACHES FOR TEXTILE RECYCLING TO BETTER MANAGE FAST FASHION WASTE

Courtesy of Risto Kirjonen

Recycling is an obvious and logical part of this idea. However, recycling goes beyond simply repurposing or reusing textiles and involves technologies that allow for the breaking down of blended materials to single basic forms before creating new products. While the public is often told “recycling” is “better for the environment”, the underlying technology on the other hand, is rarely discussed or understood.

Recycling clothes to promote circular fashion is more complex than we think.

The fast fashion business model is defined by mass production at a fast pace. For perspective, approximately 100 million metric tons of textiles are produced annually. As incredible as it seems, ~80% of this volume gets discarded either through incineration or transport to landfills, contributing at least 5% of global waste [see Figure 1]. This not only causes serious harm to our environment, but it also jeopardizes the health and livelihood of communities where these landfill sites are located, usually in the global South. 

Figure 1

The idea of circular fashion is to break the old linear paradigm of “take, make, and trash” and maximize the life of garments, clothing, or fibres either by reselling, downcycling, or recycling. Reselling (i.e., second-hand shops) and downcycling (i.e., creating a different product in an open loop recycling system) of disposed garments are done at small scale and have limited potential because these approaches simply can’t keep up with the amount waste generated by mass production. That leaves recycling as the most logical means to mitigate textile waste, especially if we could break down and repurpose the recycled materials instead of consuming virgin raw materials to generate new products [see Figure 2]. Unfortunately, due to a variety of complex factors such as regulation and implementation by legislators, consistency in the system of recycling, costly recovery process, economic benefits, and overall low-quality blended material, less than 1% of fabric to produce new fashions is generated via recycling. 

Figure 2

The urgent need for effective strategies in mitigating textile waste have encouraged the scientific community to develop various recycling technologies, which can be largely categorized into 1) mechanical recycling and 2) chemical recycling. Breaking down textile waste and processing it into new secondary raw material is challenging, especially if synthetic (i.e., polyester) and natural (i.e., wool) fibres are part of the fabric blend. Further, a substantial amount of energy is also needed and consequently, the level of carbon emission released from recycling should be taken into consideration. Therefore, choosing the most appropriate approach or technology to recycle is crucial to close the loop in circular fashion. Below we will discuss some of the mechanical and chemical recycling technologies being currently employed and their pros and cons.

Courtesy of Alessia Aucoin

Mechanical and Chemical Recycling of Textile Waste

In general, mechanical recycling follows the sequence of collection, sorting and identifying of material based on type and color, shredding, blending, and respinning into secondary raw material. There are many advantages with mechanical recycling. For example, the method has been well developed, dating back to the industrial revolution, and therefore, the techniques involved have had more time to mature. Furthermore, mechanical recycling is more cost effective and energy efficient than chemical recycling by comparison making the approach more attractive from a sustainability point of view.  However, there are caveats. Mechanical rendering can destroy the integrity of natural fibres more so than synthetic fibres resulting in an end product that is poorer quality short fibres. To compensate, virgin or primary raw material is blended with the recycled fibre to improve quality. Another shortcoming of mechanical recycling has to do with the difficulty in processing complex textile waste in post-consumer products. Because a large portion of fast fashion materials are considered poor quality and often contain synthetic material, it makes this recycling method less effective. In these cases, chemical recycling becomes the alternative approach.

Courtesy of Milagros Pereda

In chemical recycling, the complex fibers in natural and synthetic material are broken down into small monomeric building blocks and subsequently yielding textiles that are generally more superior than mechanical recycling. The downside however, chemical processing consumes a lot of energy and often involves the use of hazardous solvents and chemicals. Thus, the generation of potentially toxic byproducts for the sake of “recycling” seems to be counterintuitive.  None-the-less, with the enormous amount of fast fashion dumped in landfills every year, this might still be the most encouraging means with which to reduce our reliance on virgin materials. 

The most common technologies in chemical recycling include hydrothermal, pyrolysis, enzymatic hydrolysis, gasification, ammonolysis, and glycolysis. Without getting too deep into the chemistry behind each (you can read the scientific review by Damayanti et al.), we will briefly explain what these technology does to benefit recycling and their drawbacks.

Courtesy of Risto Kirjonen

Pros and Cons of Different Chemical Recycling Technologies

Hydrothermal: a waste decomposition process that uses chemical crystallization engineering technique at high temperatures and pressures.

• Pros: Low ash by-product and reduced oxygen content
• Cons: Long process and low purity result

Pyrolysis: a promising technology to degrade carbon-polymers.

• Pros: Relatively simple process and suitable for recycling many kinds of raw materials 
• Cons: Requires high temperature and energy consumption

Enzymatic hydrolysis: a biochemical breakdown technology that relies on a reaction with water.

• Pros: Utilizes microorganisms and requires low energy and therefore quite environmentally friendly
• Limited to the recycling of natural material and requires excessive amount of water.

Gasification: as the name implies, this technology is conducted at low-oxygen and under high temperatures up to 1000°C

• Pros: Can be employed to recycle mixed textile waste, so wider range of products.
• Cons: High energy consumption which is not environmentally friendly

Ammonolysis: this technology is the primary way to breakdown nylon 6,6, a type of nylon/plastic waste.

• Pros: Various types of textile wastes can be recycled via this process
• Cons: Uses highly toxic ammonia combined with high energy demand, i.e. conducted under pressure and temperature conditions

Glycolysis: a degradation process that convert plastic polymers to smaller molecules.

• Pros: Requires lower energy to process
• Cons: Not very selective in terms of polymer types and very low in processing.

Courtesy of Alessia Aucoin

The Fashion Industry’s Responsibility and Where Do We Go From Here?

The need for better textile waste management, largely a consequence of irresponsible production in fast fashion, has become a priority for all stakeholders in the fashion industry. Despite scientists are working to advance technologies to recycle textile waste, the fashion industry has an obligation and should be prepared to be an active participant in reducing waste to protect our planet. This could start by reducing production and minimizing the consumption of virgin materials, and preferentially choosing biodegradable materials that are readily recyclable or easy to decompose. To ease the recycling process, brands should have a fabric waste management mindset in every manufacturing and consumption stages in their business model.

Another approach to enhancing textile recyclability is making it easy to identify and sort out material especially in complex/mixed fibres. This is key to reducing energy costs. One example is the Internet of Things (IoT), an application that can be used to map all the components in textiles. This includes tracking of material diversity and location at the feedstock, pre-consumer, and post-consumer stages of the textile life cycle. IoT is essentially a digital collection platform that captures data from various sensors, including smart meters, connected to all the stakeholders in the supply chain. These data are valuable in pre-determining materials for sorting and would greatly benefit waste management and recycling efforts.

Courtesy of Milagros Pereda

Furthermore, as mentioned at the beginning only 1% of material from textile waste are recycled, and most of which are white-colored wastes. This is because our current technologies have yet to develop an effective way for removing synthetic color dyes in textiles. Even with the most advanced technology, there is no guarantee of a decolorization success, or the final color result is rather not predictable. The fashion industry needs to focus on migrating to natural dye alternatives, which are biodegradable, non-toxic, and way safer for human health. One may argue the cost and accessibility to these resources, but this why we need to practice slow fashion. Most importantly, take sustainability and recycling more seriously – consume what you need, not in excess.

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