Project ROCKY: Recycling Operations for Circular Knowledge and Yield in Plastic and Composite Waste Management

Plastic and composite wastes, particularly multi-layered and fiber-reinforced materials, remain a major barrier to achieving a circular economy due to their complex structures and limited recyclability. Recent technological advances offer promising pathways to improve recovery efficiency. This systematic review synthesizes current innovations in plastic and composite waste recycling, focusing on emerging sorting technologies, hybrid recycling processes, and circular design strategies.

A systematic literature search was conducted across major scientific databases (Scopus, Web of Science, and Google Scholar) for studies published between 2015 and 2025. Keywords included “plastic recycling,” “composite waste,” “chemical recycling,” “AI-assisted sorting,” and “circular economy.” Inclusion criteria encompassed peer-reviewed studies reporting on recycling technologies, efficiency metrics, or sustainability outcomes. Data were extracted and analyzed following PRISMA guidelines, with studies categorized by technology type and application.

A total of 78 studies met the inclusion criteria. AI-assisted sorting technologies improved material classification accuracy by up to 30% compared to conventional methods. Hybrid recycling approaches combining mechanical and chemical processes demonstrated higher recovery rates (up to 85%) for complex plastics. Composite recycling methods, including pyrolysis and solvent-based recovery, showed strong potential for fiber reclamation, although scalability remains a key limitation. Circular design interventions further enhanced recyclability and reduced lifecycle impacts.

Overall, innovations in sorting, processing, and design significantly improve the recyclability of plastic and composite waste. However, challenges related to cost, scalability, and policy integration persist. Future efforts should prioritize system-level approaches that integrate technology, design, and governance to enable sustainable and circular waste management systems.