Valorization of Post-Consumer Cotton Textiles: Technical Feasibility of Recycling Pathways

The increasing generation of textile waste, driven by the rise of fast fashion, poses significant environmental challenges across the textile life cycle, from raw material extraction and manufacturing processes to end-of-life disposal, with the majority of waste ultimately ending up in landfill. Current textile recycling practices are predominantly focused on post-industrial waste streams, which are relatively homogeneous and easier to process, while post-consumer textiles, representing significantly larger and more heterogeneous waste volumes, remain largely underutilized and are not yet recycled at scale. Addressing post-consumer textile waste therefore constitutes a critical challenge for advancing circularity in the textile sector. Within this context, cotton is a particularly relevant material for valorization. Despite being the second most widely used fiber globally after polyester, its cultivation is highly resource-intensive. Unlike synthetic fibers such as polyester, which are more readily recycled, cotton recycling faces greater technical challenges. Effective valorization of post-consumer cotton could contribute to circular economy objectives by improving resource efficiency and reducing the amount of textile waste sent to landfill. This thesis investigates the technical feasibility of two selected valorization routes for post-consumer cotton: mechanical recycling and the production of dissolving pulp for man-made cellulosic fibers. The study begins with a comprehensive evaluation of the properties of post-consumer cotton feedstock that are critical for the respective recycling pathways. This evaluation enables characterization of the starting material and identification of constraints affecting downstream processing. Based on these properties, adaptations to mechanical recycling processes are assessed with the aim of maximizing fiber valorization, including the extraction of longer fibers suitable for spinning and the utilization of shorter fibers in alternative applications. In parallel, the feasibility of substituting wood-based feedstock with post-consumer cotton in dissolving pulp production is investigated, with particular attention to process compatibility and material purity. By comparatively assessing these two recycling pathways, the thesis evaluates whether current technologies can effectively integrate post-consumer cotton and identifies which route shows greater potential for its valorization. The findings provide insights into the strengths and limitations of each pathway and highlight key technical challenges and opportunities for the effective valorization of cotton.