Abstract
Background and objectives
As part of the Danish Textile Waste Partnership established by the Ministry of Environment, this project was commissioned by the Danish EPA and carried out by the Department of Environmental and Resource Engineering at the Technical University of Denmark (DTU Sustain) between September 2023 and February 2024.
The project investigates opportunities and barriers of recycling separately collected post-consumer textiles, distinguishing between two separate collection streams. The aim is to evaluate the mass flows of discarded clothes that could be separately collected through a non-reusable 2nd stream that could potentially be available for material recycling, as well as exploring different options in terms of applicable textile-to-textile recycling technologies, with associated advantages and disadvantages.
Methodology
We use import and export flows to calculate the total supply of clothing to Danish households in 2022, divided into the 10 most common clothing categories. By means of material flow analysis (MFA), and by applying pre-determined sorting criteria, we identify the main recycling routes that an item could be eligible for. The MFA is done for each of the 10 categories, as well as the total across these categories. Finally, through available literature and expert judgements, the study examines the potential substitution rates of the recycled material.
Potentially recyclable textiles from private households
Overall consumption of clothing by Danish households in 2022 is estimated to be 98,935 tonnes, and if all discarded textiles were collected, it is expected they could be split almost evenly between 1st (~47%) and 2nd (~53%) collection stream (home sorting). Of garments potentially collected through the 2nd stream, about one third (~34%) are either dirty, wet, or contaminated, and sent to incineration (manual sorting). The remaining ~66% are both clean and dry, of which two thirds (22,937 tonnes) are found to be suitable for reuse, while the rest (~33%) are marked as non-reusable (manual sorting). This means that, of the ~52,000 tonnes of textile waste that are potentially separately collected through the dedicated 2nd stream, ~22% (11,478 tonnes) are estimated to be both clean, dry, and non-reusable, and as such potentially available for material recycling.
Fine-sorted fraction and applicable recycling pathways
After applying additional sorting criteria (fine sorting), the quantity of textiles across the different product categories that could potentially be recycled is lowered to 5,586 tonnes, while around 3,298 tonnes are estimated to be downcycled, and the remaining incinerated. However, differences are seen across product categories, with trousers and shorts, dresses and skirts, shirts, blouses, and tops and t-shirts and vests representing the categories with the highest textile-to-textile recycling potentials, while some of the most challenging categories with this regard are overcoats and anoraks, suits and blazers, and sportswear and swimwear.
Evaluating textile recycling technologies
With regards to textile-to-textile technologies for recycling post-consumer textile waste, it becomes apparent that there is currently no absolute best practice. A wide range of options are available to treat different types of garments of different fibre composition, and the evaluation of the associated pros and cons can be done following a various set of criteria.
A feedstock with a high substitution potential can be obtained via chemical recycling technologies, which on the other hand rely on an intense use of chemicals and need to repeat the textile value chain almost completely. Mechanical recycling is a mature-scale technology associated with low direct environmental impacts, but the harsh processes applied lead to output fibres of inferior quality and to a low substitution potential.
The efficiency of both mechanical and chemical methods highly depends on the purity of the input as well as on the desired output, and both are associated with a wide range of environmental impacts. When evaluating such impacts, it should be kept in mind that various categories can be affected, either directly or indirectly, by one technology or the other, and as such a too narrow focus on a single impact category can result in burden shifting.
The assessment should therefore be done in a case-by-case basis, in the absence of a one-size-fits-all type of solution, as all current recycling methods hold potential for further improvements, and trade-offs occur when focusing on one aspect or the other. Both recycling methods will likely be necessary in different combinations, requiring further improvements to process post-consumer waste more efficiently.
How to increase the amount of textile potentially available for re-cycling
The report concludes by giving an overview of some of the challenges associated with the potential recycling pathways of specific post-consumer textiles, resulting in possible recommendations for targeted textile collection and sorting. New collection methods, improvements in the communication between the different actors of the textile recycling value chain as well as clearer sorting guidelines for both the citizens and the collectors may be needed to increase separate collection and recycling rates of post-consumer textile waste.
As part of the Danish Textile Waste Partnership established by the Ministry of Environment, this project was commissioned by the Danish EPA and carried out by the Department of Environmental and Resource Engineering at the Technical University of Denmark (DTU Sustain) between September 2023 and February 2024.
The project investigates opportunities and barriers of recycling separately collected post-consumer textiles, distinguishing between two separate collection streams. The aim is to evaluate the mass flows of discarded clothes that could be separately collected through a non-reusable 2nd stream that could potentially be available for material recycling, as well as exploring different options in terms of applicable textile-to-textile recycling technologies, with associated advantages and disadvantages.
Methodology
We use import and export flows to calculate the total supply of clothing to Danish households in 2022, divided into the 10 most common clothing categories. By means of material flow analysis (MFA), and by applying pre-determined sorting criteria, we identify the main recycling routes that an item could be eligible for. The MFA is done for each of the 10 categories, as well as the total across these categories. Finally, through available literature and expert judgements, the study examines the potential substitution rates of the recycled material.
Potentially recyclable textiles from private households
Overall consumption of clothing by Danish households in 2022 is estimated to be 98,935 tonnes, and if all discarded textiles were collected, it is expected they could be split almost evenly between 1st (~47%) and 2nd (~53%) collection stream (home sorting). Of garments potentially collected through the 2nd stream, about one third (~34%) are either dirty, wet, or contaminated, and sent to incineration (manual sorting). The remaining ~66% are both clean and dry, of which two thirds (22,937 tonnes) are found to be suitable for reuse, while the rest (~33%) are marked as non-reusable (manual sorting). This means that, of the ~52,000 tonnes of textile waste that are potentially separately collected through the dedicated 2nd stream, ~22% (11,478 tonnes) are estimated to be both clean, dry, and non-reusable, and as such potentially available for material recycling.
Fine-sorted fraction and applicable recycling pathways
After applying additional sorting criteria (fine sorting), the quantity of textiles across the different product categories that could potentially be recycled is lowered to 5,586 tonnes, while around 3,298 tonnes are estimated to be downcycled, and the remaining incinerated. However, differences are seen across product categories, with trousers and shorts, dresses and skirts, shirts, blouses, and tops and t-shirts and vests representing the categories with the highest textile-to-textile recycling potentials, while some of the most challenging categories with this regard are overcoats and anoraks, suits and blazers, and sportswear and swimwear.
Evaluating textile recycling technologies
With regards to textile-to-textile technologies for recycling post-consumer textile waste, it becomes apparent that there is currently no absolute best practice. A wide range of options are available to treat different types of garments of different fibre composition, and the evaluation of the associated pros and cons can be done following a various set of criteria.
A feedstock with a high substitution potential can be obtained via chemical recycling technologies, which on the other hand rely on an intense use of chemicals and need to repeat the textile value chain almost completely. Mechanical recycling is a mature-scale technology associated with low direct environmental impacts, but the harsh processes applied lead to output fibres of inferior quality and to a low substitution potential.
The efficiency of both mechanical and chemical methods highly depends on the purity of the input as well as on the desired output, and both are associated with a wide range of environmental impacts. When evaluating such impacts, it should be kept in mind that various categories can be affected, either directly or indirectly, by one technology or the other, and as such a too narrow focus on a single impact category can result in burden shifting.
The assessment should therefore be done in a case-by-case basis, in the absence of a one-size-fits-all type of solution, as all current recycling methods hold potential for further improvements, and trade-offs occur when focusing on one aspect or the other. Both recycling methods will likely be necessary in different combinations, requiring further improvements to process post-consumer waste more efficiently.
How to increase the amount of textile potentially available for re-cycling
The report concludes by giving an overview of some of the challenges associated with the potential recycling pathways of specific post-consumer textiles, resulting in possible recommendations for targeted textile collection and sorting. New collection methods, improvements in the communication between the different actors of the textile recycling value chain as well as clearer sorting guidelines for both the citizens and the collectors may be needed to increase separate collection and recycling rates of post-consumer textile waste.
| Original language | English |
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| Publisher | Danish Environmental Protection Agency |
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| Number of pages | 54 |
| ISBN (Print) | 978-87-7038-623-4 |
| Publication status | Published - 2024 |
| Series | Miljoeprojekter |
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| Number | 2266 |
| ISSN | 0105-3094 |