Advancing secondary raw material flows through cleaner production: integrating mechanical recycling and eco-design of post-industrial textile waste

The transition towards a circular textile economy requires approaches that simultaneously address material recovery, design for recyclability, and product durability. However, these dimensions are often addressed independently in the existing literature, resulting in limited operational integration between recycling processes and product design decisions. This study proposes an integrated engineering–design methodology that combines mechanical recycling of post-industrial polyester–cotton cutting waste with eco-design strategies aimed at enabling circular and resource-efficient garment production under realistic industrial conditions. The approach encompasses waste characterisation, optimisation of fibre opening parameters, yarn and fabric production incorporating 30% recycled content, and the development of a functional capsule collection guided by design for disassembly and recyclability principles. The optimisation of the mechanical recycling process improved fibre length by up to 28% relative to baseline opening conditions, enabling the production of yarns with tenacity values in the range of 15 - 16 cN/tex, approaching industrial reference values for comparable yarns counts. Fabric production using the optimised yarn demonstrated that mechanically recycled fibres can be incorporated into structurally stable woven fabrics within conventional spinning and weaving infrastructure. Beyond material performance, eco-design principles were applied to minimise mixed components, support durability-oriented design choices, including long-lasting aesthetic design and repair-friendly garment construction, while maintaining recyclability and facilitating future recycling. The study therefore demonstrates how process-level constraints of mechanical recycling can be translated into practical garment construction rules that support circularity. Environmental implications are discussed as screening-level estimates derived from literature-based assumptions. Under these assumptions, diverting 1 tonne of cutting waste from incineration to mechanical recycling may potentially avoid approximately 2.4 t CO 2 -eq emissions and save 8–10 m 3 of water, although a full scenario-based life cycle assessment remains necessary to confirm these impacts. Overall, the results indicate that mechanical recycling optimisation and eco-design can function as complementary levers to operationalising circular textile production, while highlighting technical trade-offs and industrial constrains that require further validation.