Waste Management 79 (2018) 8–21
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Development and testing of a sorting and quality assessment method for textile waste Nynne Nørup a,b,⇑, Kaj Pihl b, Anders Damgaard a, Charlotte Scheutz a a b
Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark Ulandshjælp fra Folk til Folk – Humana People to People, Kildebrogårdsvej 11N, 4622 Havdrup, Denmark
a r t i c l e
i n f o
Article history: Received 20 March 2018 Revised 15 June 2018 Accepted 3 July 2018
Keywords: Household textile waste Clothing Textile definition Residual waste Quality assessment Sorting method Textiles sorting
a b s t r a c t Due to the high resource consumption and environmental impacts of textile production, better handling of discarded materials has a great environmental improvement potential. A uniform definition of textile waste and a stringent sorting procedure is a precondition for thorough investigations of discarded textiles. A review of waste sorting studies showed that only a few included textiles, and mainly considered content and not quality. A lack of definition and quality assessment causes a high risk of mistakes when assessing the potential of textile waste prevention. This study establishes a method for sorting and quality assessment of textiles in household waste, validated through dialogue with professional textile sorting centres. It also suggests a minimum waste sample size. The quality assessment is based on analysis of product types, manufacturing methods, fibre composition and a product condition assessment based on 17 criteria. The developed method was applied in a case study and compared with other sorting methods. It showed that 61% of the clothing in residual waste and 83% in small combustibles and that 78% of the household textiles in residual waste and 85% in small combustibles was reusable or recyclable. The comparison with existing methods showed that sorted quantities varied significantly when different sorting methods were applied even when the sorting was done on the same sample. This study suggests a new standard for defining and assessing categories and qualities of used textiles, adapted to real contemporary sorting technologies, and tested on waste samples. Ó 2018 Elsevier Ltd. All rights reserved.
1. Introduction The textile sector is one of the most polluting industries in the world. In the EU alone, clothing and household textiles are the fourth most polluting products, seen from a lifecycle perspective (Beton et al., 2014). Globally, 3% of all greenhouse gas emissions are caused by the production and use of textiles (Laitala et al., 2012). Textile production is connected to major environmental costs in terms of the consumption of energy, water, chemicals and nutrients, as well as increased impacts on land areas in connection with cotton cultivation (WRAP, 2012). In Denmark and Sweden, the consumption of clothing and household textiles has increased, respectively, by 62% (2003–2008) and 40% (the period 2004–2014) (Tojo et al., 2012; Palm et al., 2014). In general, the consumption of textiles is rising, not only because of an increase in the population, but also because increased prosperity has also
⇑ Corresponding author at: Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark. E-mail address: firstname.lastname@example.org (N. Nørup). https://doi.org/10.1016/j.wasman.2018.07.008 0956-053X/Ó 2018 Elsevier Ltd. All rights reserved.
meant that countries such as China are beginning to approach European and American levels in this regard (Bartle, 2010). Despite the large environmental impact of textiles, textile waste has only within the recent years started being governed as a part of the waste area (Danish EPA, 2012). Therefore, there is a need to investigate how textiles are handled in the best possible way in environmental terms within the waste sector. Textiles presumably constitute a smaller waste fraction, but the potential contribution to climate change from production is very high per weight unit (Palm, 2011), which means that the potential for environmental improvement is also high, even if in small quantities. This environmental improvement potential can be realised by ensuring that textiles are collected, reused, recycled and disposed of in the best possible way (Farrant et al., 2010). Only few studies were found that have included textiles waste and in most cases only quantities of disposed textiles were considered (e.g. Hedeman et al., 2006; Saidan et al., 2016; Wagland et al., 2012). Knowledge about the quality of the disposed textiles is thus very limited, though it is crucial in order to assess whether textile materials can be reused, recycled or actually treated as waste. Merely two Swedish studies and one Norwegian study have examined their quality in terms of
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residual waste and small combustibles. The Swedish studies showed that 59% and 61% of the textiles could be reused, and in the Norwegian study this figure was 28% (Avfall Sverige, 2013; HultĂŠn et al., 2016; Laitala et al., 2012). Quality is determined by the condition of the individual product, how it has been produced and fibre composition. Furthermore, quality depends on whether materials are assessed in relation to their use in the investigating country or whether they are sorted and dispatched to the international market â€“ and at what sorting centre they are separated. Therefore, it is essential to know the basis of the quality assessment. Particularly for lower quality clothing and household textiles, sorting centresâ€™ marketing approaches vary, which is essential for whether items will be reused, recycled or regarded as waste. What can be reused or recycled changes over time, which contributes further to the need to know the criteria for quality assessment. These criteria are also crucial for the development of collection systems and recycling technologies, so the separation of textiles from the waste must be carried out with this in mind. Still, the majority of existing sorting guidelines for household waste only cover textiles as a fraction, i.e. without definition or consideration of their applicability, and deficient definitions make it unclear what the textile fraction includes (e.g. Nordtest, 1995; ASTM, 2003, 2008). Moreover, the use of the textile quantities in additional analyses becomes complicated and it is impossible to compare sorted quantities across studies. In the few guidelines and methods found that contain any form of quality assessment criteria are simplified to an extent that makes it difficult to assess their objectivity (e.g. Avfall Norge, 2015; Avfall Sverige, 2013; HultĂŠn et al., 2016). When sampling small waste amounts, it is very
important that the results are presented not only by weight, as a single heavy product can constitute a large proportion of a category and thus give a distorted impression of differences in terms of quality. Thus the overall purpose of this study is to develop and test a method for studying the quantities and quality of textiles in household waste, in order to reduce the amount of items disposed of alongside general household waste. The specific objectives are to: (i) define what constitutes textile fraction and quality, (ii) develop a quality assessment that includes product type, manufacturing method and fibre composition, (iii) test and evaluate the method in a specific waste sorting campaign, and finally (v) compare the results by using methods described in the literature. This study showed that the lack of a clear definition, sorting method and quality assessment presents a high risk of errors when assessing amounts and potential of improving the separate collection of textiles in the waste. This study provides such new definitions and methods tested on waste samples. 2. Materials and methods 2.1. Definition of textile fraction and quality 2.1.1. Definition of the textile fraction The textile definition shown in Table 1 is based on EU Nomenclature Chapters 61â€“63 and is applied through sorting campaigns and dialogue with professional textile sorting centres (Appendix A, Table A1). Hereby, a functional definition that enables data collection (quantities and quality) for use in mass flow analysis, environmental assessments and other analysis work has been
Table 1 Overview of the definition of textile fractions in residual waste, divided into three sub-fractions: Clothing, Household textiles and Other textiles. The â€˜Other textilesâ€™ fraction contains all textile products that are not included in the other two fractions. Clothing
25 product types:
13 product types:
Types of products included: duvets, shoes, belts, toys, yarn hats, caps, flags, bean bags, cushions, textile pieces and parts of soft furniture (couch cushions or couch cover)
1. 2. 3. 4. 5. 6.
1. 2. 3. 4. 5. 6.
T-shirts Tops Blouses Shirts Trousers Shorts
Linens Decoration pillowcases Bedcovers Curtains Towels Dishtowels
7. Winter clothing (with and without insulation) 8. Dresses
9. Skirts 10. Vests 11. Jackets 12. Infantsâ€™ clothes, incl. socks & gloves 13. Workwear 14. Apron
9. Rags 10. Tablecloths 11. Place mats 12. Plaids 13. Pieces of household textiles Household textiles matching the listed products made in leather are also included Home-made products are included as well
15. Swimwear 16. Underwear 17. Nightwear 18. Bathrobes 19. Socks 20. Gloves 21. Scarfs & ties 22. Handkerchiefs 23. Costumes 24. Parts of clothing 25. Pieces of clothing Clothing matching the listed products made in leather is also included Home-made products are included as well
Belts, shoes and bags made of leather are also included Product types not included: Carpets with underlay Upholstery, if not for the entire couch, box mattresses or armchairs Any kind of obvious production waste, e.g. fibres, balls of cotton Any kind of disposable personal hygiene products, disposable diapers as well as disposable napkins, table cloths and gloves
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achieved. The textile fraction consists of three sub-fractions (clothing, household textiles and other textiles), which must be divided further into product type, thus giving a clear and constant understanding of what the fraction may consist. The quality assessment in the method only covers Clothing and Household textiles. The fraction of Other textiles is included to ensure that they are all potentially sorted from waste. Other textiles thus highlight which products are at risk of being sorted out when in fact there is no limited textile definition. Note that the list of products under Other textiles is made up of examples (Table 1), as the number of products that can be made from these materials is very extensive. 2.1.2. Definition of quality Quality is defined by whether Clothing and Household textiles can be reused, recycled or considered as waste (Table 2).
Table 2 Definition of reuse, recycling and waste, including three quality categories (A, B and C) for reuse. Reuse
(A) Product types that can definitely be reused. (B) Product types that still are functional but have minor defects. The products are kept by their owner, mended or sent to a professional sorting centre. The definitions of textiles with minor defects that are still reusable are based on the international market for low quality clothing and household textiles and consist of products with small stains, minor holes and broken zippers. (C) Rags (wipers), as these do not fit in the normal reuse system. They can still serve their purpose, even with stains. Avoidable conditions are not a hindrance for reuse. Product types that are not reusable but can be recycled. The recyclability of a textile product is determined by its fibre composition, how it is produced and its size. Avoidable conditions are not an obstacle to recycling. Product types that cannot fulfil the requirements for being reused or recycled.
Reuse is divided into three sub-qualities, namely A, B and C (Table 2). Quality A includes products that can be reused in their current state, while Quality B includes products that are still functional but have minor defects. These products will be reusable by either the original owner or by consumers in the international textile reuse market. In order for the products to reach the international market, they must be sorted professionally and sold accordingly. Quality C includes only rags for reuse. The reason why rags have their own category is that they are only sold in the international reuse textile market if they are brand new. However, rags are still fully functional even with defects such as stains. Products with avoidable conditions, such as being soiled by other waste, are still considered reusable or recyclable, since these conditions could be avoided if the textiles were handled and disposed of properly (see Section 2.2.2). A flawless sweater, therefore, which is dirty from being thrown out in residual waste is still considered to be Quality A. Non-reusable products can be recycled when their condition, manufacturing method and fibre composition make it possible. If the product cannot be either reused or recycled, it is considered to be waste. An assessment of quality in relation to Table 2 is performed on the basis of the sorting method, as described in Section 2.2. 2.2. Method for the sorting and quality assessment of Clothing and Household textiles The method consists of two parts, namely sorting and quality assessment, each consisting of two levels (Fig. 1). In this section, sorting is described (Level 1 and 2), while quality assessment (Level 3 and 4) is described in Section 2.2.2. 2.2.1. The sorting The initial sorting campaign must follow general guidelines for sorting household waste, as described by Edjabou et al. (2015) and
Fig. 1. Model for sorting and quality assessment of Clothing and Household textiles.
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Nordtest (1995). As the majority of Clothing and Household textiles are not discarded on a daily basis, the sample must have a certain volume to ensure an accurate result for both volume and quality. The method is based on NRF (2005), guidelines for the random testing of household waste, based on examinations of sample sizes in relation to the amount of textiles in waste. At Level 1, the textile fraction is manually sorted from the waste. At Level 2, it is sorted into the three sub-fractions clothing, household textiles and other textiles, as defined in Section 2.1. In order to avoid overlap between other textiles and other waste fractions, a list should be made of products sorted as other textiles.
2.2.2. Quality assessment of Clothing and Household textiles Quality assessment of Clothing and Household textiles is very complex and depends on several factors. Level 3 therefore consists of four steps (I to IV), as shown in Table 3. Step I determines the product type, for example trousers, shirts, curtains, etc., which is crucial to the remaining steps in the quality assessment, as it portrays information about the size of the textile and whether there should be a pair for the product to be functional. There are 25 product types for clothing and 13 for household textiles. Step I-I describes additional product specifications for all products; underwear, for example, is divided into bra types and undershirts, to find information on the size of the textile material in the product, as it is relevant to the final quality assessment.
In Step II, product types are sorted according to the manufacturing method – is the textile made of knitted fabric (hosiery) or woven fabric? Additional information about the manufacturing method, such as lining or velour, should be noted in Step II-I. This information is used to evaluate the recyclability. The manufacturing method is important to determine whether the surface of the product is absorbent and how easily the material can be shredded (Elander and Ljungkvist, 2016; Danish EPA, 1997; Wulfhorst et al., 2006), since tightly woven fabrics such as shirts, for instance, are harder to shred than knitted fabrics. In Step III, the fibre composition of the product types is investigated, primarily to determine the recyclability of the clothing and household textiles. The specific fibre composition is found by reading the statutory label in the products. Where this is not possible, a physical judgement is made as to whether the clothing and household textiles are made from natural or synthetic fibres – or a mixture thereof. Knowledge of typical fibre types or fibre compositions for a variety of products must support this assessment. If it is not possible to determine the fibre type, the composition must be noted as ‘unknown’. Although some fibre combinations are more frequent than others, the variation is high, in which case fibre composition is divided into seven groups to provide an overall overview of fibre-level composition (Table 3). ‘Natural fibres’ are naturally occurring fibres, i.e. cotton, wool, silk, etc., or they are based on natural products such as viscose. ‘Oil-based fibres’ are based on (the refining of) oil, such as polyester, acrylic and
Table 3 Overview of Level 3: the different steps for sorting Clothing and Household textiles after quality. Level 3 Step
Quality assessment Sorting criteria
Sorting into products:
Clothing (25 products): T-shirts, tops, blouses, shirts, trousers, shorts, winter clothing (with and without insulation), dresses, skirts, jackets, vests, work wear, infants’ clothes incl. socks + gloves, underwear, nightwear, bathrobes, socks, gloves, scarfs, ties, handkerchiefs, costumes, parts of clothing and pieces of clothing
Household textiles (13 products): linens, decoration pillowcases, bedcovers, curtains, towels, dishtowels, facecloths, potholders, rags, tablecloths, place mats, plaids, pieces of household textiles
Products requiring further specifications:
Household textiles: The same as above, e.g. linen is sorted further into kinds of linen, like pillowcases, bed sheets, etc.
Clothing: The same as above, e.g. underwear is sorted further into kinds of underwear, like types of bra, etc. Knitted/tricot fabric
Woven Tricot fabric: jersey, double-face, fleece, etc. Woven: corduroy, velour, flannel, etc. Fibre composition (six compositions): natural fibres, manmade fibres (including viscose), mixed fibres, estimated fibres composition, leather and unknown Natural-based fibres and oil-based fibres are divided into 13 sub-groups*: 100%; 50 50%; Mix of two, one 50–59,9%; Mix of three, one 50–59,9%; Mix of three, one 60–69,9%; Mix of two, one 70–79,9%; Mix of two, one 80–89,9%; Mix of tree, one 80–89,9%; Mix of three, one 90–99,9%;
Mix of three all less than 50%; Mix of two, one 60–69,9%; Mix of three, one 70–79,9%; Mix of two, one 90–99,9%;
Mixed fibres are divided into 12 groups: the same as for natural- and oil-based fibres except from 100% Estimated: Natural fibres; cotton, wool, etc. Manmade fibres: synthetic, polyester, etc. Mixed fibres: cotton-mix, cotton/cotton-mix, wool mix, etc. Unknown Leather IV *
Assessment of the state of the product type
Imprecise label Assessing the clothing and household textiles for defects, avoidable conditions and informal use
All ranges, except 100%, must be understood as such that the product consists of several fibres, of which one fibre type is a value within the range mentioned.
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elastan. â€˜Mixed fibresâ€™ are mixed natural and oil-based fibres. â€˜Natural fibresâ€™ and â€˜Oil-based fibresâ€™ are divided into 13 subgroups and â€˜Mixed fibresâ€™ into 12, which are shown in Step III-I in Table 3. The number of subgroups in â€˜Estimated fibre compositionâ€™ depends on the knowledge level of the products, as well as oneâ€™s experience with identifying the fibre. â€˜Leatherâ€™ consists of products consisting primarily of leather. â€˜Imprecise labelâ€™ is where the label is not sufficient and â€˜Unknownâ€™ consists of products where it has not been possible to identify the fibre composition. In Step IV, the condition of the products is assessed on the basis of the criteria shown in Table 4. When searching for defects, the defectâ€™s nature, extent and location on the product are noted. In Step IV, the product type, determined on Step I, is used to assess if a minor defect, such as a hole, makes the product unsuitable for recycling. For example, jeans can still be used as jeans if there are holes on the knees, but not if there are big holes in the crotch. There is no international reuse market for underpants with minor holes; therefore, they can only be reused by the original owner, unlike the example of jeans. However, this process is very complex, and in order to reduce subjectivity, the assessment should be based primarily on the international reuse market. If the product cannot be reused, larger products, knitted products and cotton/natural fibre products can be recycled more frequently. A frequent recycling method involves the manufacture of rags, which requires that the product can be cut from a garment at a minimum size of 30 30 cm, has an absorbent surface and is made of a minimum 70% cotton (Elander and Ljungkvist, 2016). If doubt exists, the product should be evaluated as the lowest quality. â€˜Conditions that can be avoidedâ€™ are essential to register, as they may affect the weight of the product type and make it difficult to investigate for defects, though they will have no effect on the functionality of the product. Composition of the waste to be sorted may mean that all clothing and household textiles found will need to be considered dirty by definition, due to contamination by other waste. If in doubt as to whether the product has been made dirty by remaining waste, or was dirty as a result of discarding, it should be noted as both conditions. Based on the information provided at Levels 1â€“3, the overall assessment is made on Level 4 as to whether the individual product can be reused, recycled or treated as waste. For each individual product, all conditions must be noted and similar product types with the same quality assessment grouped and weighed together. The weight will be noted, and it is important to make it clear whether it is wet weight, which will mean that the clothes were moist when thrown out, or it has become moist before weighing
is included, or whether the clothes have been dried first. In this study, all values are given as wet weight. 2.3. Case study: testing of the method and comparison with other methods The sorting method was tested on residual and small combustible waste from two different areas, as well as compared to results obtained on the basis of other sorting methods. 2.3.1. Field of study The residual waste came from an area (Serup) in Jutland, which is representative of the residual waste collection system in many parts of Denmark, whereby households have only one waste bin for residual waste and there is no mandatory collection of source-sorted waste. Fractions like glass and paper, garden waste, hazardous waste, WEEE and bulky waste can be disposed of at municipal collection sites or recycling stations. Small combustible waste came from Gentofte Municipality, where there is a municipal recycling station that can be used by citizens and small businesses from the municipality and surrounding areas. The station is arranged to sort 27 fractions into 35 containers. In the two areas (Serup and Gentofte), there were no separate collections of textiles in the waste system. However, sorted textiles could be handed to charity organisations, either at dedicated charity shops or clothing containers located in different places in the municipality and at recycling sites. The amounts of textiles collected in the areas through charity organisations are unknown. 2.3.2. Waste collection The collection of residual waste followed standards and sorting guidelines, as posited by Nordtest (1995) and Edjabou et al. (2015), as well as guidance for sample sizes in relation to textile sorting (NRF, 2005). Residual waste, generated over two weeks, was collected from 100 households by following normal collection procedures, in order to avoid behavioural changes in handling the residual waste. Residual waste was collected separately for the sampling area, without compression, and transported to a sorting area where it was manually sorted. Three container loads of small combustibles were collected, corresponding to the number of containers available for the fraction at the recycling site, and the guidelines for taking samples followed Edjabou et al. (2015), Nordtest (1995) and NRF (2005) guidance for sample size relative to textile sorting. The waste was collected
Table 4 Overview of the criteria used to assess the state of Clothing and Household waste in Step IV (see Table 3). Criteria
Conditions where it is essential: which product type it is, where the defect is and how extensive it is and whether the product has more than one defect This is crucial: Product type Defect location Defect size Is there more than one defect?
Conditions that can be avoided
Wear and tear Holes Stains Faded/discoloured Paint Over-washed Zipper Single glove/sock (solo) Other things Thrown out dirty Becomes dirty in residual waste Wet Moist Used as cloth Cut into pieces Other
Conditions where it can be difficult to determine when the defects have occurred and which may affect the assessment of whether the product has defects. They can also affect the weight of the product type The product is used for purposes other than the original; this may be both with and without processing of the product. Clipping of products is considered as informal recycling
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reports and five sorting guidelines for household waste sorting, of which textile was one of the sorted fractions. An overview of these sources and specific conditions for some of the methods can be found in Appendix B, Table B1. The EU’s Swa-Tool (Method 1) guidance provided the most thorough description of the textile fraction. The definition of textiles and sorting method in the NRF (2005) sorting guide (Method 2) are similar to the definitions and methods used in the majority of the articles (11 articles, cf. Apendix B, B1). However, it does have some examples of what the fraction may contain and does relate to the significance of the sample size, specifically for the sorting of textiles. The ASTM (2003/2008) sorting standard (Method 3) is the method most referred to in the reviewed articles (five articles
without compression and transported to a sorting area where it was manually sorted. As seen from Table 5, the total amount of residual waste was 1563 kg, collected from 100 households, and for small combustibles the total amount of waste was 6432 kg. 2.3.3. Comparison of six methods for textile sorting and quality assessment In order to highlight the importance of a defined definition and provide a thorough method for the sorting and quality assessment of textiles, the results of the study (Method 6) were compared with results from five different sorting methods (Methods 1–5). The methods (Table 6) were selected after a review of 26 articles, three
Table 5 Overview of collected waste. Table 5a gives an overview of residual waste, showing the type and number of households, numbers of citizens per household and amount of collected and sorted waste. Table 5b gives an overview of the catchment area, number of users and the amount of collected and sorted small combustible waste. 5a. Residual waste
5b. Small combustibles
Dominant housing type in the area Number of households in the area Number of citizens per household Amount of residual waste collected (kg) Total amount of sorted waste (kg) a b
Single family 100a 2.6a 1563 1563
Citizens in the catchment area Annual number of users in 2015 Total annual amount of small combustibles in 2015 (ton) Amount of collected small combustible waste (kg) Total amount of sorted combustible waste (kg)
890,000b 211,466b 2930b 6432 5593
Petersen et al. (2016). Gentofte Municipality (2017).
Table 6 Overview of the five methods used to compare the consequences of definition and quality assessment, as well as an overview of how it is sorted afterwards. Method
1. EU SWA-Tool 2004
2 NRF 2005
3 ASTM 2003/2008
4 Avfall Norge 2015
Household textiles Clothing
5 Liikanen et al. (2016)
(8) Textiles, shoes and bags
Shoes Household textiles Clothing
(8.1) Shoes and bags, (8.2.1) Clothing, (8.2.2) Other textiles
Clothes (T601) Natural and man-made clothing items excluding shoes Ex: trousers; skirts; socks; stockings; tights; underwear; shirts; blouses; Jumpers; cardigans; coats; hats; gloves (T602) Natural and man-made textiles and furnishings Ex: balls of wool; blankets; braids; carpets; cloths; cords; curtains; Household soft furnishings and upholstery; mats; pillow cases; pillows; Rags; ropes; rugs; sheets; threads; towels Wool, cotton, syntactic textiles – clothing, towels, curtains, linens, carpets etc. Textiles, rubber, leather, and other primarily burnable materials not included in the above component categories Towels, linens, curtains, tablecloths, pillows All types of clothing that can be suitable for reuse, including nice underwear Pairs of shoes not to worn out or damaged Textiles that are clean, but worn out and damaged and unsuitable for reuse Textiles that are clean, but worn out and damaged and unsuitable for reuse Textiles that are dirty and thrown out dirty or clearly been wet when thrown out. Worn out and damaged shoes. Single shoes. Small and worn out underwear and socksc 8.2.1 and 8.2.2 is classified as recyclable
The code in parenthesis refers directly to the specific ID code for the fraction in the method. N.D. indicates there is no definition given for this level. Therefore, the lowest level defined for this method is used. c The guide classifies dirty and wet clothing as not applicable but points out where an attempt to distinguish between thrown out dirty and/or wet or become dirty and/or from being thrown out. b
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– cf. Appendix B, Table1), and the Avfall Norge (2015) (Method 4) sorting guide and Liikanen 2016 (Method 5) method include a quality assessment of textiles. All five methods were tested on the dataset from the case study, to ensure a similar basis for comparison. The sorting follows the level of detail in each method, which means, for example, that Method 1 is only sorted to Level 2, since there is no additional information (Table 6). It is important to note that Methods 1, 2 and 3 include other products in the textile fraction than the textile definition of this study (Table 1), even when the ‘Other textiles’ fraction is included (Table 6). For Method 5, there is no description of the content of the fraction besides naming. Where there is doubt about the placement of a product, it is not included. Therefore, Methods 4 and 5 follow the study assessment of what is included in the Level 1 textile fraction. The quality assessment is only carried out in Methods 4 and 5, since the other methods do not include an evaluation (Table 6). In Method 4, reusable household textiles constitute a limited number of product types, and so only the specifically listed household textile products are assessed (Table 6). The quality assessment in Method 4 also includes shoes and pillows, which in this study are included under the subfraction ‘other’ textiles. The fraction ‘non-useable’ in Method 4 is considered waste. 3. Results and discussion Sections 3.1 and 3.2 refer only to the results using this study method. In Section 3.3, the results of this study are compared with results obtained using the five methods reviewed in Section 2.3.3. 3.1. The amount of textiles and the importance of sub-fractions The total textile content in the residual waste was 2.9% of the total amount, while the total textile content in small combustibles was 7.7% (see Fig. 2). Furthermore, in the residual waste, Clothing and Household textiles amounted to 2.1%, while it was 4.3% in small combustibles. The higher proportion of other textiles in small combustibles (3.4%) compared to residual waste (0.8%) may be due to different waste habits when disposing waste. Disposal through small combustibles is typically done in connection alongside the disposal of larger quantities of waste, while there are limits on
how much waste can be put into household residual waste bins. Petersen et al. (2011) indicated in their study that larger residual waste containers lead to larger amounts of waste and poorer waste sorting. That the amount of Household textiles represents the smallest amount in both residual waste (0.6%) and small combustibles (1.6%) is probably due to two reasons. First, the amount of Household textiles in a household does not increase in line with the number of residents to the same extent as the amount of Clothing, and second, it is presumed that the lifespan of Household textiles in Denmark is still expected to be significantly longer than for Clothing, since the consumption of Household textiles is primarily functional-oriented rather than fashion-minded. An overview of the product types found in Other textiles can be found in Appendix C, Table C1. Other textiles are not included further in the quality assessment. 3.2. Quality assessment 3.2.1. Product types and manufacturing method Fig. 3 shows product compositions in Clothing (Fig. 3a) and Household textiles (Fig. 3b). In both residual waste and small combustibles, the range of products thrown out is high; however, in Clothing, there is significantly greater variation in the type of products that are disposed of through small combustibles (24 products) than in residual waste (15 products). Rags account for most of the Household textiles in the residual waste (33%) and weight wise represent a large proportion of the Household textiles in small combustibles (4%) (Fig. 3b). Fig. 3a and b shows that small textile products are not only thrown out with residual waste, since underwear and facecloths are seen in both waste types, while the handkerchiefs in this study only occur in small combustibles. Knowledge of the product types is crucial when assessing quality, as the significance of other factors in the assessment depends on it. In addition, products also contribute to additional knowledge of the manufacturing method, as certain product types are often made either by knitting or weaving. In particular, it turned out that further specification of the product types in Step I-I was supplementary to specifying the manufacturing method in Step II-I. Knowledge of the manufacturing method contributes in itself only to an overall assessment of the applications possible for clothing or household textiles; for example, knitted products are more
Fig. 2. Textile content (%) in the residual waste and small combustibles divided into three sub-fractions: Clothing, Household textiles and Other textiles.
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Fig. 3. (a) Distribution of products in Clothing as a percentage of the total amount of Clothing in the residual waste and small combustible respectively. (b) Distribution of products in Household textiles as a percentage of the total amount of Household textiles in residual waste and small combustibles, respectively.
Fig. 4. The fibre composition in Clothing and in Household textiles in residual waste and small combustibles, respectively.
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likely to be recycled than woven fabrics. However, in order to really evaluate the potential for recycling, the manufacturing method must be compared with the product type as a minimum. For example, T-shirts and regular socks are often made in the same way, but whereas T-shirts can often be recycled as rags, regular socks are apparently not recycled, due to their size. However, if the socks were made of rough knitwear (such as home-knitted socks), they could probably be recycled, because this type of knit is more often recycled through shredding, where the size of the product is less important. Information about the type of knit is available in Step II-I. In this study, it was not possible to determine all of the manufacturing methods in Step II-I, but by supplementing information about product type in Step I-I, it was possible to take this into account. The detailing of the manufacturing method in Step II-I contributes to an overall understanding of complexity and which kind of recycling will be most likely.
3.2.2. The fibre composition of Clothing and Household textiles It was possible to assess the fibre composition for more than half of the Clothing and Household styles in small combustibles. In addition, an amount (about 8% for Clothing and 42% for Household textiles) can be added that was estimated on the basis of information from other levels and products of the same type (Fig. 4). For residual waste, fibre composition could be determined for about half of the amount of Clothing when including the estimated amount, while 67% of the amount of Household textiles could be determined in the same regard (Fig. 4). Fig. 4 shows that the fibre composition in Clothing is determined to a greater extent from the label, whereas most of the fibres in Household textiles are estimated and thereby unknown. It is important to be aware that composition is calculated on weight and not on the number of products, so a heavy product without a label may mean that the proportion of the amount of fibre composition that can be determined in fact changes. However, fibre composition calculated solely on quantity can be used for an overall assessment of the environmental potential, for example recycling rather than combustion. Since fibre composition is determined primarily from the label of a product, the method is considered to be valid and of low risk to an incorrect assessment. An assessment based solely on the
experience and feel of textiles, however, can lead to significantly incorrect assessments; for instance, a chemical analysis of the material that a professional sorting centre separated as being 100% cotton was actually found to contain products in which the cotton content was only 50–70% (Östlund et al., 2015). In order to estimate fibre composition, some knowledge on typical fibre compositions for products in a particular country and area is required, as well as experience in how the different fibres feel to the touch. Another way to assess fibre composition, for example, would be through chemical analysis, combustion analysis or microscopy (ASTM, 2012), any one of which would provide a more accurate result that would take into account that the fibre composition may have changed due to the washing and use of the textiles. Such analyses are demanding, though, as they must be performed on each individual product to provide a more accurate indication of composition than using the method in this study. In addition, it is not only fibre composition that determines whether a product can be recycled, which is also taken into account herein. In the absence of a label or any other possibility of making a valid estimation of fibre composition, the recyclability of the product in this study was determined from the product type, manufacturing method and condition (Appendix E, Fig. E1).
3.2.3. Assessment of the quality of clothing and household textiles The research shows that approximately 51% of Clothing and 61% of Household textiles in residual waste can be reused, and correspondingly 63% of Clothing and 62% of Household textiles in small combustibles have a second use (Fig. 5). If the recyclable share is added to, respectively, by approximately 10% and 16% for residual waste and 22% and 24% for small combustibles, it is even more apparent that there is a great potential for improving the collection of Clothing and Household textiles (Fig. 5). Fig. 6a and b also shows that the majority of reusable Clothing (36% in residual waste and 56% in small combustibles) and Household textiles (respectively 32% in residual waste and 56% in small combustibles) is of Quality A, which means it consists of products without defects. Evaluating the condition of the rags in the Quality C category also showed that, unlike other Household textiles, it was increasingly thrown out without defects. The smaller amount of reusable Household textiles compared to the amount of reusable
Fig. 5. Overall distribution of the quality of Clothing and Household textiles in residual waste and small combustibles, respectively.
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Fig. 6. (a) Composition of the quality of Clothing as a percentage of the total amount of Clothing in residual waste and small combustibles. (b) Composition of the quality of Household textiles as a percentage of the total amount of Household textiles in the residual waste and small combustibles. NB: In this study, all Clothing and Household textiles that were found in the residual waste are considered dirty due to ‘Other waste’ – this depends on the composition of the residual waste (see Appendix E, Fig. E1 for further specifications on quality).
Fig. 7. (a) The product composition in the different qualities of Clothing as a percentage of the amount of the individual product in Clothing, (b) product composition in the different qualities of Household textiles as a percentage of the amount of the individual product in Household textiles. RW: residual waste. SC: small combustibles.
Clothing can be explained by two factors. The main reason is that Household textiles are used in Denmark primarily according to functionality, and thus the most common reason why Household textiles are disposed of is that they simply wear out. Second, the international reuse market for products with minor defects (Quality B) is smaller for Household textiles than for Clothing. However,
as mentioned earlier, this does not apply to the discarded rags of Quality C, which would most likely be used only in homes. Fig. 6 a and b also shows that the difference between the recyclable amounts in residual waste and small combustibles is that residual waste consists primarily of ‘informal use’ products (about 3%), while small combustibles consists primarily of ‘one defect’
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products (about 16%). The reason why some of the products labelled ‘informal use’ could still be recycled was that the informal recycling consisted of the products being cut into pieces. In the part of the Clothing considered to be waste, the reason was normally due to ‘One defect’, but fibre composition and manufacturing method, meant that it was unrecyclable. Fig. 7a and b shows that there is a relatively even distribution of the different types of products in the reusable part of both Clothing and the Household textiles in residual waste and small combustibles, respectively. It is not just big products that are thrown out that are reusable, such as T-shirts or towels, but it is also underwear and rags. Fig. 7b also supports the image of rags (Quality C) being primarily thrown out in a reusable state. Only about 1% of the rags in small combustibles had defects that would render them waste, while 10% of the rags in the residual waste had such defects (Fig. 7b). In residual waste, seven of the 15 product types in Clothing could be reused, while in small combustibles it was three out of 24 product types. Fig. 7a illustrates that all workwear and socks in residual waste were in a condition that was considered waste, while in small combustibles only, all ‘‘Part of the Clothing” was considered waste. In the Household textiles, two of the seven product types in residual waste could be recycled, while in the small combustibles it was possible for just one of the 13 product types (Fig. 7b). None of the product types in the Household textiles, in either residual waste or small combustibles, was considered to be waste only. Fig. 7a and b indicates that the complexity of Clothing is higher than Household textiles; however, it is the overall assessment of the individual product that is essential for the final assessment of its quality. Fig. 8a and b shows fibre composition in various levels of quality, namely reuse, recycling and waste, in Clothing and Household textiles, respectively. The assessment of fibre type by checking the label was easiest in the reusable products. In the recyclable items, there were a number of products that were cut into pieces, and therefore there were no labels. The amount of ‘Mixed fibre’ in the recyclable Clothing (Fig. 7a) must be seen in relation to two aspects. First, products with an absorbent surface and over 70% cotton can be recycled (Elander and Ljungkvist, 2016), and second, heavy products such as trousers are often recycled if they are denim jeans, even though they are woven and more frequently made from cotton-blended synthetic fibres. The finding that clothing made from ‘Oil-based fibres’ is the largest waste category (Fig. 8a and b) can be explained by the fact that the recycling possibilities for oil-based fibres are smaller and largely dependent on how the product is manufactured. However, fibre composition must be seen in relation to product type (Fig. 7a and b) and the assessed condition (Fig. 6a and b). For exam-
ple, a piece of workwear that is rated as waste may mean that the overall assessment changes completely, which is why it is important that the sample size is large enough and that the quality is seen in relation to it. Generally, it is a very complex undertaking to assess the applicability of textile products, as each product must be evaluated in terms of both reusability and recyclability. Figs. 6–8 show that recyclability especially depends on many conditions. In this study, applicability is held up against current practice in four international sorting centres, rather than a purely theoretical assessment (Appendix F, Table F1). By setting the assessment as shown in Figs. 6–8, it is possible to gain insights into the basis for the assessment, thus making it possible to analyse what a change in the market means. Methodologically, it was easier to assess reusability rather than recyclability, as it is relatively easy to determine whether the functionality of a product is intact. However, it can be discussed whether cosmetic conditions make the product useless. Therefore, Quality B was assessed on the basis of the international market requirements for reuse, rather than on whether the original owner would be able to use the product. This emphasises the importance of knowing the international textile trade market, as the criteria for what can be reused are dynamic and depend primarily not only on economic conditions, but also the availability of reusable textiles and alternatives. It is debatable whether it is ethically sound to count on a market for lower quality goods; however, division into Quality A and B is also applicable to a general understanding of the potential for reducing textile products in waste, in line with EU legislation on following the waste hierarchy. The results of the quality assessment in this study, as seen in Figs. 5 and 6, are in line with the results of the Nordic Council of Ministers report ‘Exports of Nordic Used Textiles: Fate, benefits and impacts’. The same report also discusses the pros and cons of a market for lower quality reuse and the recycling market (Watson et al., 2016). Compared to previous quality studies, another Norwegian study showed that significantly less could be reused (28%), while two Swedish studies showed that, respectively, 59% was reused and 61% could be reused and recycled, which is comparable to this studýs results (Avfall Sverige, 2013; Hultén et al., 2016; Laitala et al., 2012). Conversely, one should be careful about comparing the results directly, as there are different textile definitions and quality assessments in the previous studies. The significance of the lack of insight into how these results have arisen is discussed further in Section 3.3. The method in this study provides an insight into the potential for reducing Clothing and Household textiles in waste, and how this potential can be realised. For example, it is possible to assess whether there is better environmental benefit in finding a use for
Fig. 8. (a) Fibre composition in Clothing in the different qualities of Clothing as a percentage of the total amount of Clothing, (b) fibre composition in Household textiles in the different qualities of Household textiles as a percentage of the total amount of Household textiles.
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single product types than in reducing the amount of products that have been used ‘informally’. In Appendix G, further details of the impotency of the different criteria for assessing the quality of products are discussed. 3.3. Comparison of different sorting methods 3.3.1. The importance of definition and sorting Fig. 9 shows the amount and composition of sorted textiles, using six different methods. Total textile content in residual waste varied between 2.3% (Methods 1 and 2), 2.8% (Methods 4, 5 and 6) and 4.3% (Method 3). In small combustibles, textiles content varied between 6.3% (Methods 4, 5 and 6), 11.3% (Methods 1 and 2) and 37.8% (Method 3). When sorting by Method 3, significantly larger amounts of textiles were obtained, due to the fact that the method does not actually sort out textiles per se but a mixed fraction called ‘combustibles/other non-organic’, in which textiles are included. It can be argued that it is possible to sort textiles out from this amount, but the results will be similar to the results for Methods 2 or 5, because of the lack of a sorting method. Methods 1 and 2, respectively, provide a smaller amount of textiles in residual waste and a greater amount in small combustibles, due to the fact that these two methods do not include shoes but do include carpet with backing. That fact that the quantities using Methods 4 and 5 (Fig. 9) are the same as when using the method developed in this study (Method 6) can be due to two reasons – either they actually give the same result in relation to the overall amount of textiles or the quantities are actually too small, as this study has not included products for which there was any doubt as to whether they were covered by the textile fraction in the methods. In general, the results of the five methods depend on what the individual user understands as constituting a textile. Even with Method 4, which has the best explanation on which parts of the sub-fraction to include, there is no explanation whatsoever of what the ‘nonuseable (waste)’ sub-fraction contains. It is assumed that it contains products unsuitable for reuse and recycling, but whether, for example, it might also may contain soft furniture, hygiene products and toys is unclear. The method for this study (Method 6) provides insights into which product types are in the different sub-fractions, whereas for the other methods it is only possible to obtain the total amount of either the entire textile fraction or
a given sub-fraction. As seen in Fig. 9, it means that in Method 3 it is not possible to tell how much is actually classed as textiles, and with Method 2 one can only see the amount thereof. With Methods 1 and 5, the clothing sub-fraction gives an indication of what the fraction contains, while it is unclear what the ‘nonclothing/other textiles’ sub-fraction may contain. It is thus only because the comparison is made on the same dataset and compared to the results of this study (Method 6) that insights can be obtained on what the amounts consist of. 3.3.2. The importance of the method for assessing the quality of clothing and household textiles The quality assessment shown in Fig. 10 is only done for Methods 4, 5 and 6. The figure illustrates that in spite of the same amounts in Methods 4, 5 and this study (6), the assessment of quality is different. The proportion of textile content considered reusable or recyclable varies between 40% (Method 4), 47% (Method 6) and 75% (Method 5) in residual waste and 34% (Method 4), 47% (Method 6) and 77% (Method 5) in the small combustibles. These differences are due to the varying definitions of what the sub-fractions contain as well as the assessment criteria. Method 4 estimates that 60% of the textile content in residual waste and 66% in small combustibles was waste (Fig. 10). Compared to the results of this study (Method 6), it is evident that only 24.4% of the textile content in residual waste and 8.9% in small combustibles is considered as waste, while 29.1% of textile content in residual waste and 44% small combustibles is not assessed (Fig. 10). It is important to remember that the quality assessment in Method 4 includes certain products, which in this study are represented by the sub-fraction Other textiles and thus are not quality-assessed. Shoes and duvets weigh considerably more per item than many of the other products. Method 4 supports the notion in this study of a need to set up better management of the sub-fraction Other textiles. It will therefore not be correct just to conclude that in this study it may be considered as waste. Method 4 is significantly better than Method 5, as it considers both reuse and recycling as well as explains the need to assess the products. However, the lack of specification in the quality assessment makes Method 4 subjective and difficult to apply, as the assessment is left to individual sorters and the use of the results is also made difficult and up to the individual’s interpretation.
Fig. 9. Composition of the textile fraction in the waste when using the following six methods: Method 1 EU SWA Tool 2014, Method 2 NRF, 2005, Method 3 ASTM 2003/2008, Method 4 Avfall Norge, 2015, Method 5 Liikanen et al. (2016) and Method 6, namely the method used in this study.
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Fig. 10. The quality of the textile content, evaluated using Methods 4 and 5 and the method used in this study (6). NB: Note the method in this study only assesses the quality of Clothing and Household textiles. A more detailed figure is found in Appendix H, Fig. H1.
Method 5 estimates 75% of the textile content in residual waste and about 77% in small combustibles as recyclable (Fig. 10). It is important to remember that the assessment is based solely on a methodological determination of the two sub-fractions and not an assessment made of the individual product. As shown earlier in the review of the method, and the results of this study, recyclability is the most complex part of the assessment of textiles and depends on many aspects. Combined with Method 5, and also considering the ‘other textiles fraction’ as recyclable albeit without specifying what it contains, it is unrealistic on a theoretical level that the two sub-fractions can be completely recycled. The advantage of Method 5 is that it is simple and that ultimately it provides an incentive to look at the use of fractional textiles. However, it does not outweigh the fact that the assessment alone is based on the assumption that all textiles can be recycled, as well as the completely neglected environmental advantage in prioritising reuse. 4. Conclusion and perspective This study has developed and tested a method for assessing the quantity as well as quality of textiles disposed of in household waste. The quality assessment includes an analysis of product types, manufacturing methods and fibre composition as well as an assessment of an item’s condition. When using the method, it is shown that while the amount of Clothing and textiles is small in relation to the total amount of waste, namely 2.1% in residual waste and 3.8% in the small combustibles, the potential for improving separate textile collection is high. Testing on clothing and household textiles from residual waste (31 kg) and small combustibles (about 241 kg) showed that nearly 61% of and nearly 78% of textile in residual waste, and 83% of and 85% of textiles in small combustibles, could be reused or recycled. The quality assessment is thus comprehensive but necessary in order to assess whether textiles can be reused or recycled. It is possible to present data for the total amount of clothing and household textiles, but the assessment must be made on each piece of textile product. Moreover, it is easier to assess reusability than recyclability, since an evaluation of reusability depends primarily on the condition of the textile products, while the assessment of recyclability depends on the product type, i.e. its condition, how it has been made and its fibre composition.
Comparing the method of this study with previous methods it can be concluded, that a clear definition of the textile fraction is crucial, as the amounts that are sorted may vary significantly without this clear definition. Furthermore the comparison showed that without this clear definition the following quality assessment, the results will be very uncertain. The proposed method is therefore essential to understand the specific textiles discarded in waste, and thus the potential for improving the collection. This is clearly identifying a need for more research in the potential for minimizing the textiles in the household waste. Acknowledgments The work presented herein is part of an industrial PhD project hosted by Humana People to People and The Technical University of Denmark (DTU). The PhD project is funded by the Innovation Fund Denmark (File No. 0603-00523B), Humana People to People and DTU Environment. The authors would like to thank ECONET for making the sorting campaigns possible. We would also like to thank Humana People to People in Lithuania, Slovakia, Bulgaria and Turkey for assisting in the validation in the preparation of the textile definitions and quality assessments. Specifically, we wish to thank Rita Starkauskienė at Humana in Lithuania for her contribution of knowledge and experience to the quality assessment. Appendix A–H. Supplementary material Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.wasman.2018.07. 008. References ASTM, 2003. Standards test Methodes for Determinination of the composition of unprocessed municipal solid waste (D5231–92). ASTM International, West Conshohocken, USA. ASTM, 2008. Standards test Methodes for Determinination of the composition of unprocessed municipal solid waste (D5231–92). ASTM International, West Conshohocken, USA. ASTM, 2012. Standard Test Methods for Identification of Fibers in Textiles1 (D276– 12). ASTM International, West Conshohocken, USA.
N. Nørup et al. / Waste Management 79 (2018) 8–21 Avfall Norge, 2015. Veileder – plukkanalyser av husholdningsavfall (in Norwian), Rapport 10/2015, ISBN: 82-8035-018-7. Avfall Sverige, 2013. Textilt avfall, En framtida resurs – pilotprojekt i Stockholm(in Swedish), Rapport U2013:15, ISSN: 1103-4092. Bartle, A., 2010. Fiber Recycling: Potential or Saving Energy and Resources, Institute of Chemical Engineering. Vienna University of Technology, 1060, Vienna. Beton, A., Dias, D., Farrant, L., Gibon, T., Le, G.Y., Desaxce, M., Perwuelt, A., Boufateh, I., Wolf, O., Kongoulis, I.S., Cordella, M., Dodd, N.P., 2014. Environmental improvement potential of textiles (IMPRO textiles), 2014. EUR - Scientific and Technical Research Reports. https://doi.org/10.2791/52624. Edjabou, E.M.E., Jensen, M.B., Götze, R., Pivnenko, K., Petersen, C., Scheutz, C., Astrup, T.F., 2015. Municipal solid waste composition: Sampling methodology, statistical analyses, and case study evaluation. Waste Manage. 36, 12–23. https://doi.org/10.1016/j.wasman.2014.11.009. Elander, M., Ljungkvist, H., 2016. Critical aspects in design for fiber-to-fiber recycling of textiles, IVL Swedish Environmental Research Insitute. Mistra Future Fashion report number 2016, 1 http://mistrafuturefashion.com/wpcontent/uploads/2016/06/MFF-report-2016-1-Critical-aspects.pdf. EU SWA-Tool, 2014- Methodology for the Analysis of Solid Waste (SWA-Tool) User Version, European Commision, iC consulenten ZT GmbH, Austria, Kaiserstrasse 45, A-1070 Vienna, https://www.wien.gv.at/meu/fdb/pdf/swa-tool-759-ma48. pdf (Accessed December 8, 2017). Farrant, L., Olsen, S.I., Wangel, A., 2010. Environmental benefits from reusing clothes. Int. J. Life Cycle Assess 15, 726–736. Hedeman, B., Burvall, J., Nilsson, C., Marklund, S., 2006. PCDD/F in source-sorted waste fractions and emissions from their co-combustion with reed canarygrass. Waste Manage. 27 (11), 1580–1592. https://doi.org/10.1016/j. wasman.2006.08.008. Hultén, J., Johansson, M., Dunsö, O., Jensen, C., 2016., Plockanalyser av textilier i hushållens restavfall- En kartläggning av mängder och typ av kläder, hemtextilier och skor (in Swedish), Sveriges Meteorologiska och Hydrologiska Institut, 601 76 Norrköping, ISSN: 1653-8102. Laitala, K., Klepp, I.G., Morley, N., Meistad, T., Chapman, A., Chen, W., Hebrok, M., Daae, J., Austgulen, M.H., 2012. Potensiale for økt materialgjenvinning av tekstilavfall og andre avfallstyper (papir/papp, metall og glass) (in Norwian) Rapport TA -2994, Statens institutt for forbruksforskning (SIFO) Grensesvingen 7, 0661 Oslo. Liikanen, M., Sahimaa, O., Hupponen, M., Havukainen, J., Sorvari, J., Horttanainen, M., 2016. Updating and testing of a Finnish method for mixed municipal solid waste composition studies. Waste Manage. 52, 25–33. https://doi.org/10.1016/ j.wasman.2016.03.022. Gentofte Municipality, 2017. Personal communication with M. Frøding Cand. scient, Gentofte Kommune, Teknik og Miljø, Forsyning, Affald og Genbrug Bernstorffsvej 159, 1. sal, 2920 Charlottenlund. Nordtest, 1995. Municipal solid waste: Sampling and characterisation (No. NT ENVIR 001), Nordtest Method. Espoo, Finland.
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Published on Aug 11, 2018