AATCC Journal of Research DOI: 10.14504/ajr.7.S1.3 Supply Chain of Waste Cotton Recycling and Reuse: A Review By Sara Johnson, Darlene Echeverria, Richard Venditti, Hasan Jameel, and Yuan Yao, North Carolina State University Abstract A comprehensive understanding of the waste cotton supply chain and different end-of-life options is essential to promote cotton recycling and reuse. This study analyzed global and US data to understand the quantity, current sources, and destinations of waste cotton. Globally, 11.6 million metric tons of waste cotton are generated per year during cotton garment production. This study also reviewed different options for recycling both pre-consumer and post-consumer cotton waste via chemical and mechanical processes. Different applications of waste cotton were compared to their virgin counterparts from technical, environmental, and economic perspectives. Unlike most previous studies, this research included applications that are not traditional textile products (e.g., biofuels and composites), shedding light on potential new markets for waste cotton that will not compete with virgin cotton. Key Terms Cotton End-of-Life, Cotton Reuse and Recycling, Cotton Waste, Mechanical and Chemical Recycling, Supply Chain Introduction effort to transit European economies toward circular reuse of materials, especially focusing on textile collection and Global cotton production exceeded 26 million metric tons recycling.9 In the United States, the Council for Textile 1,2 in 2018 to meet the growing demand for textile products. Recycling measured a 40% increase in textile waste between 1 Cotton represents a third of the total textile market, and the 1998 and 2009 with only a 2% increase in landfill diversion. production is projected to increase by 6.5% in 2019. Grow- In response, the Council set a goal for the United States to ing cotton production places stress on the environment, produce zero landfill-bound textile waste by 2037.10 In the with respect to land, chemicals, and water. In 2004, cotton textile industry, several companies are developing industrial- 3 production accounted for 2.6% of global water use. Cotton scale technologies to upcycle waste cotton using mechanical production also uses significant chemicals, including pesti- and chemical recycling methods. Start-up companies such 4 cides. It was estimated that cotton cultivation accounted for as Evrnu11 in the United States, Renewcell12 in Sweden, and 5 11% of the world pesticide consumption in 2013. TeKiDe in Finland have been developing industrial-scale Virgin cotton is mainly used as the raw material for clothing, chemical recycling of post-consumer cotton, in which cotton which is then worn and disposed. The US Environmental garment waste is dissolved into and extruded as a fiber.13 Protection Agency (US EPA) estimated that 9.5 million Another example is Recover, a Spanish company that shreds metric tons of apparel and textiles end up in landfills each pre-consumer waste while maintaining the staple length of year in the United States,6 and less than 1% of the clothing the cotton fiber so it can be respun.14 7 produced is recycled back into new clothing. However, it Established companies such as Lenzing15 are looking to add was estimated that more than 80% of the cotton wastes are recycled yarn to their supply chain in hallmark products. suitable for mechanical recycling into new textiles.7 A study Lenzing, one of the largest textile companies in the renew- estimated that if textile waste is all diverted from land- able fiber business, launched Tencel lyocell made with fills, there would be sufficient starting material for a viable Refibra technology in 2016. The company introduced pre- recycled cotton industry.7 Using recycled cotton has the consumer waste cotton, in addition to wood pulp, into their potential to reduce the use of water, energy, pesticides, and Lyocell product with a goal of further including post-con- dyeing chemicals, and reduce landfill waste.8 sumer waste cotton.15 Large fashion brands such as H&M, Some opportunities to enhance waste cotton recycling Levi’s, and The North Face have begun recycling programs and reuse have been explored at the policy, industry, and that reward their customers for bringing back old clothing. academic levels. For example, the 2015 European Union H&M increased its annual textile collection from 12,000 to (EU) Circular Economy Action Plan launched a three-year 21,000 metric tons of garments from 2015 to 2018.16 19 | Vol. 7, No. Special Issue One Sustainability 2020Delivered by Ingenta IP: 192.168.39.151 On: Sun, 26 Sep 2021 19:52:36 AATCC Journal of Research Given the growing technological interest in cotton recycling, strategic planning and decision making for large-scale pro- significant efforts have been made in academic research to motion and adoption of waste cotton recycling and reuse. address technical barriers in cotton reuse, such as character- izing different types of the mixed textile waste,17 enhancing Review of Supply Chain of Waste separation efficiency of cotton from polyester blends,18,19 and Cotton Streams developing value-added products from waste cotton that can be used in place of virgin material.20,21 Waste cotton is produced at almost every step in the produc- tion of a cotton garment. A good understanding of the type, Despite the current movement in the cotton recycling field, quantity, and quality of the waste cotton alone within the there are knowledge gaps that hinder the implementation and supply chain will be helpful to identify hotspots suitable for adoption of cotton recycling and reuse. First, there is a lack recycling and reuse. Fig. 1 is an estimation of cotton waste of understanding of waste cotton supply chains. The waste generated in the global supply chain of cotton and garment cotton supply chain can be complex and have large variations production using standard cotton processing methods. The across various companies and regions. A confident estimation percentages shown in each box represent the ratio of input of quantity and quality of waste cotton available at different material that is wasted or does not flow to the following steps. supply chain stages is essential to inform decision making for end-of-life options. Second, although some studies have Production begins with the cultivation of cotton, where evaluated the technical feasibility and environmental benefits waste is left in the field to decompose. Next, in the ginning of different waste cotton options, few of them have provided process, cotton fiber is separated from the lint (~35% of seed cotton) is separated from cottonseed and trash, and a comprehensive review and comparison of different applica- 22 tions from a life-cycle perspective. lint is used in the next spinning process. For the non-lint fraction, ~85% is the cotton seeds that can be used to make This paper addresses the previous two knowledge gaps by oil or stock feed, and the remaining 15% is classified as a providing a comprehensive review of waste cotton sup- waste product.22 However, this waste product is potentially ply chains in the United States and different waste cotton usable for ethanol manufacturing, fertilizer, or oil spill applications from technical and environmental perspec- clean-up.22 Next, the cotton fiber travels in bales to be spun. tives. Global data and analysis of supply chain and material In preparation for spinning, the bales are opened, blended, flow for countries other than the United States were also cleaned, and carded. In the carding process, studies showed reviewed for comparisons. Both mechanical and chemical that 4.7% of the material is separated as waste, and of that recycling, and the potential applications of recycled fibers waste, in flat and undercard wastes, 65% and 56% of the were reviewed and compared with virgin counterparts. The fiber has the potential to be recovered, respectively.23 Next, data collected and presented in this paper will be helpful for in the drawing process, the sliver is blended, straightened, further quantitative analysis related to the cost and envi- and the density is adjusted to the desired level. In the ronmental impacts of different end-of-life options for waste combing process, the final waste is removed to obtain fine, cotton. The review and discussions could also inform future strong, smooth, and uniform yarn. Combed yarn is more Fig. 1. Annual fiber waste generated during global cotton garment production from August 2018 to July 2019.1,6,22–28 Delivered by Ingenta Sustainability 2020 Vol. 7, No. Special Issue One | 20 IP: 192.168.39.151 On: Sun, 26 Sep 2021 19:52:36 AATCC Journal of Research expensive than carded yarn and creates a high-quality prod- 1999, in the United Kingdom, 43% of used clothes went uct; however, the process removes on average 20% as waste.24 to second-hand clothing, 22% to filling materials, 12% to This waste is largely usable in applications requiring cotton wiping cloths, and 7% to fiber reclamation.32 The Textile linter quality material, such as dissolution and respinning.20 Recycling Association in the United Kingdom estimated that in Europe on average about 15–20% of disposed textiles Next, in preparation for spinning, the sliver is condensed were collected while the rest was landfilled or incinerated. and lightly twisted into a finer strand or roving. The rov- Of the collected material, about 50% was down-cycled and ing is spun using one of three main systems: ring, rotor, or 50% was reused, mainly through exporting to developing air-jet spinning. While waste can vary based on the spinning countries.33 However, there are large variations within Euro- process and machine, yarn waste is about 5%.25 Finally, the pean countries. Germany collected about 70% of disposed yarn is woven into fabric on a loom.