An environmental assessment of the collection, reuse, recycling and disposal of clothing and household textile waste

Nynne Nørup

    Research output: Book/ReportPh.D. thesis

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    The textile sector is a highly polluting industry, in terms of the high emission of greenhouse gases, and has many resources tied up in the production of each piece. The consumption of textiles is high, and rising, especially for clothing, the worldwide figures for which are projected to grow to 160 million tonnes annually in 2050. Nevertheless, it is only in recent years that textiles have been integrated into the waste area as an independent waste fraction that requires separate handling. In spite of this increased focus, there is a real lack of data and knowledge on the topic, especially on assessing the potential for improving collection, studies into what used textiles actually replace through further sales for reuse and recycling and assessments of the environmental effects of improved management.
    Previous environmental assessments (such as life cycle assessments (LCAs)) indicate that the best waste treatment of textiles follows the waste hierarchy. However, these environmental assessment studies, particularly in relation to the waste management of disposed textiles, have been limited by a lack of data. Furthermore, despite the fact that international textile sorting centres are essential for ensuring the highest possible use of textiles, the database for these is severely inadequate, and the replacement rate for sorted textiles is a crucial factor in environmental assessment studies where the database is almost non-existent. The replacement rate is used to determine how much reused clothing replaces the purchase of new clothes. In general, textiles are complex to model in an example LCA, and this complexity increases when looking at the textile waste fraction. The proper handling of textile waste requires determining each product according to whether it can be reused or recycled, depending on the type of product, its state, method of manufacture and fibre composition.
    As a result of an EU requirement to ensure the mandatory separate collection of textiles, an increase in this practice is expected, and so it is important to clarify how large quantities can potentially be collected and what the quality of these are. Most textiles currently collected are exported from Western countries, mainly due to the very high consumption of new clothing, so with any collection, it will be even more relevant and urgent to include concrete collection, sorting and handling details in environmental assessments such as LCAs.
    The purpose of this PhD study is therefore to assess the environmental potential of an increase in the collection of textiles from Danish households. The environmental assessment is based on determining the potential for collecting more textiles from the Danish household waste, thereby improving data on the collection, handling and sorting of discarded textiles, and determining the replacement rates for second-hand textiles in three African countries.
    The focus on the potential of household waste was chosen because material flow analysis (MFA) studies have indicated that the potential is highest from households, and because the potential in the waste represents a quantity of textiles citizens have decided to discard. In order to determine this potential, it was necessary to develop a definition of textiles and a method for assessing their quantity and quality in waste. A review of the literature showed that this lack of a clear definition and method means that the amounts of textiles found in waste vary greatly at between 1% and up to 22% of the total amount of waste. Developing the definition and method was an iterative process based on a literature study, field study and waste sorting, as well as an evaluation of the method in relation to previous methods. The definition and method were applied to collected waste samples of residual waste and small combustibles from recycling stations, and this formed the basis for determining the Danish potential to increase the collection of textiles from household waste.
    An MFA, a life cycle inventory (LCI) and an economic analysis were used to analyse an international textile sorting centre’s mass flows and sorting rates, with the purpose of generating data for use, for example, in an environmental assessment.
    The replacement rates of used textiles exported and sold in Angola, Malawi and Mozambique were established based on a total of 3,485 face-to-face interviews and 14,100 products, and the statistics program JMP was used for data management and replacement rate calculation. The calculation model itself was the same as found in a previous study of the replacement rate, which is why the results are comparable, albeit the study was also used to evaluate the method especially in relation to its use in an African context.
    Based on the identified potential for increasing the collection of textiles from Danish households, and improved data for the textile management system, an LCA model was set up in EASETECH to assess the environmental benefits of realising this potential. This was done by setting up four scenarios: 1) Scenario 0, a baseline scenario with no sorting; 2) scenario 0a, which only included sorting out the potential found in rags; 3) scenario 1 where the full potential was sorted out followed by sorting at an international textile sorting centre; and 3) scenario 2 where the full potential was sorted out followed by sorting at a Danish textile sorting centre.
    The results of the studies carried out showed that with a clear and functional definition and method for sorting textiles. The amount of textiles in household waste was small, but compared to the yearly consumption of new textiles per Dane it was high. In residual waste, an average of 1.4 ± 0.5% was Clothing, and an average of 0.6 ± 0.3% was Household textiles (based on weight). On an annual basis, this corresponds to 2.4 ± 1.9 kg Clothing and 1.1 ± 0.5kg Household textiles per citizen in Denmark. In small combustibles discarded at Danish recycling stations, an average of 4.5 ± 2.1% was Clothing and an average of 2.6 ± 1.2% was Household textiles. However, in terms of the quality of the fraction, the potential for improvement was high. In the residual waste, an average of 65 ± 8% and 65 ± 19% of Clothing and Household textiles, respectively, could be reused, while an additional average of 12 ± 5% and 15 ± 11%, respectively, could have been recycled. For small combustibles, an average 69 ± 6% of Clothing and 66 ± 10% of Household textiles could be reused, while an average 14 ± 4% of Clothing and an average 16 ± 9% of Household textiles could be recycled. In the residual waste, a large share of the reusable Household textile potential consisted of rags that were discarded in a condition similar to new (21± 15%). Both the definition and the method are essential to ensuring that the generated data are usable across different types of analyses and that there is transparency in relation to, for example, the validity of the results. In relation to understanding how a given potential can be realised, a clear method for determining quality is important, as there are differences in the possibilities of reusing, for instance, a rag compared to a blouse.
    The study of the international textile sorting centre showed that although the import of textiles into the facility increased in the period 2015-2017 (total imports were 35,739 tonnes in 2015, 35,668 tonnes in 2016 and 36,292 tonnes in 2017), the share of sorted textiles for reuse decreased from 80% to 75%. Furthermore, it was not just the quantity that fell, but also the quality of the reusable textiles, which was reflected in the fact that sorting levels from the centre’s fine sorting unit fell from 33% to 29%, and this happened at the same time as an increase in imports of pre-sorted textiles only fine-sorted. This in turn led to the consumption of more resources to sort out a tonne of reusable textiles. In addition, the costs of sorting amplified, especially for those categories demanding the most sorting, including the categories from fine sorting. Exports to countries outside Europe also increased during the period. At the same time, the amount of textiles exported for recycling increased from 13% to 17% and waste from 5% to 6%.
    The replacement rates for African countries were found to be lower than expected (63 ± 6% Angola, 35 ± 1% Malawi and 37 ± 5% Mozambique, average 45 ± 4%), demonstrating not only the need for the replacement rate to be based on actual investigations, but also the need for more knowledge and further development of the method for determining replacement rates in general. In this study, there was a strong indication that the respondents’ economic purchasing power affected the outcome of the replacement rates, seen in relation to both a national and a cultural context. Thus, the respondents did not have the opportunity to buy new textiles, which meant that the replacement rates were higher in the African countries, the richer the respondents were, while this seemed to be the opposite in the few previous studies conducted in European countries.
    The environmental assessment showed that even by only ensuring that rags are (re)used in households, there is a considerable environmental benefit in terms of avoided CO2-eq emissions (-1.4 kg per person or equal to -7,899 tonnes for the total Danish population). By modelling the full potential for increasing collection, the best handling method would save 30.2 kg of CO2-eq per person (172,104 tonnes for the total Danish population). Having the total potential sorted in Denmark only gives a saving of 12.4 kg CO2-eq per person, as less textiles would be sorted out for reuse or recycling, and because a larger share of the textiles are sorted out as waste. However, it should be considered that these savings are uncertain estimates, as the modelling of textiles in LCAs is extremely complex and highly limited by sparse data. Even with the large data collection in this PhD thesis there is still a need for improvements, especially with regards to the impact from production of textiles and the replacement rates.
    This PhD study has been part of the Innovation Foundation’s industrial PhD programme and has been a collaboration between the Department of Environmental Engineering at the Technical University of Denmark (DTU Environment) and the charity organisation Ulandshjælp from Folk til Folk - Humana People to People (UFF-Humana).
    Original languageEnglish
    Place of PublicationKgs. Lyngby
    PublisherTechnical University of Denmark
    Number of pages65
    Publication statusPublished - 2019


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