Valorization of Raw Wool Waste as a Sustainable and Biodegradable Alternative Infill for Artificial Turf Systems

This study presents a sustainable circular economy approach to valorize raw wool waste by developing engineered, biodegradable bio-pellets as a functional replacement for styrene-butadiene rubber (SBR) infills in synthetic turf systems. To overcome physical limitations and address upcoming regulatory restrictions on microplastics (Regulation (EU) 2023/2055), raw wool was processed into dense pellets through controlled water inclusion and compounding with density-increasing mineral additives (Dolomite and Barite). Thermogravimetric Analysis (TGA) was utilized to precisely quantify the inorganic fractions and thermal stability of the resulting formulations. The physical, mechanical, and biomechanical behavior of the wool-based composites was comprehensively evaluated, focusing on Shock Absorption (SA), Vertical Deformation (VD), and Energy Restitution (ER) across different elastic subbases. Results confirm that the developed bio-pellets fit within the stablished ranges of international mechanical standards (EN 15330-1, FIFA, and World Rugby). Furthermore, moisture-induced swelling permanently enhances damping performance and prevents particle displacement, while the intrinsic hydrophilic nature of the keratin matrix could provide hydro-thermal stabilization and reduce electrostatic charges compared to conventional SBR crumbs. By leveraging existing fertilizer processing infrastructure, this work demonstrates a scalable route to transform a problematic agricultural waste into a high-performance, non-toxic, and eco-friendly material for advanced engineering applications.