Victoria Bustos-Terrones
Crop residues are increasingly recognized as strategic biomass resources rather than disposal problems, yet many are still burned or poorly managed, causing emissions, air pollution, and soil degradation that limit their role in the circular bioeconomy. This scoping review maps recycling and valorization pathways for crop residues within a circular-bioeconomy framework, integrating technological readiness, environmental performance, and socio-economic dimensions. Using PRISMA-ScR methodology, 145 documents (2013-2025) from academic and institutional sources were analyzed. The review characterizes residue typologies and global generation patterns, and examines key valorization routes including composting, anaerobic digestion, biochar and thermochemical conversion, lignocellulosic biorefineries, bioplastics and biocomposites, recovery of bioactive compounds, and emerging nanomaterial and biofabrication pathways. Beyond individual technologies, the analysis highlights the importance of compositional characteristics and integrated and cascading systems that link residue properties with suitable processing routes and products. Mature options such as composting and anaerobic digestion (TRL 7-9) deliver benefits in soil health, nutrient recycling, and rural energy, whereas intermediate and emerging routes offer higher value creation but face stronger techno-economic, regulatory, and social barriers. Life-cycle assessment studies indicate substantial greenhouse gas mitigation and improved resource efficiency when residues are diverted from open burning, despite tradeoffs related to logistics, energy demand, and soil cover requirements. The article proposes a 2025-2040 roadmap prioritizing product standardization, low-energy pretreatments, integrated thermochemical-biological systems, green finance and cooperative governance, repositioning crop residues as key resources for circular bioeconomy strategies in emerging regions.