Abstract
The accumulation of blended-fiber textile waste poses a significant environmental challenge. Conventional recycling processes are often unable to efficiently process textile blends due to their heterogeneity. Blended fibers are typically composed of a wide variety of synthetic and natural fibers, dyes, and coatings. The inability to separate and reuse valuable materials such as polyester, nylon, and cellulose fibers limits the potential for a sustainable circular economy. In this work, this challenge is addressed by designing and simulating a chemical recycling route for mixed textile waste using Aspen Plus®. The overall process concept is selected based on a systematic screening of existing valorization approaches and implemented based on results from a lab-scale study. In a glycolysis reaction, polyester is depolymerized into bis(2-hydroxyethyl) terephthalate (BHET), which is the main product of the process. Nylon and cotton fibers are retrieved as intact fibers. Selected process variables of the most expensive unit operations are optimized. Additionally, two modifications to the process design are evaluated. A number of key performance indicators (KPIs) are calculated to evaluate the economic, thermodynamic, environmental and societal impacts. The process is simulated at a textile waste feed rate of 5000 kg/h. The calculated BHET minimum selling price of 2.03 $/kgBHET for the glycolysis-based recycling process is approximately four times larger than the market price. The process has an exergetic efficiency of 72.9%. A gate-to-gate life cycle assessment reveals green house gas emissions of 0.01 kgCO2eq/kgtextile compared to 5.88 kgCO2eq/kgtextile for incineration and 3.6 kgCO2eq/kgtextile for fluidized bed combustion. The waste reduction rate for the glycolysis-based recycling process amounts to 71.4%, with solvent purge streams being the only waste generated. Although the process is currently not cost-competitive, it shows significant potential for recovery of BHET and simultaneous separation of other fibers. Overall, the process represents a technically promising approach, combining a low carbon footprint with the potential to achieve high circularity in the textile industry, especially with further technological advancements or supportive policy frameworks.