From Urban-Industrial Symbiosis towards Smart Sustainable Cities, a Pathway for Circular and Carbon-neutral Cities

Rapid urbanisation has intensified resource pressures, with cities consuming over 75% of global resources. This paper reviews the evolution of Industrial Symbiosis (IS) into Urban-Industrial Symbiosis (UIS) between 2010 and 2024, focusing on how Smart City (SC) infrastructures enable city-wide circular resource flows. The study combines a scoping review of 92 peer-reviewed studies with five illustrative city cases to examine how digital systems can coordinate multi-sectoral resources in urban environments. The analysis identifies three persistent barriers: governance fragmentation, financial risk, and technological limitations, and matches them with digital and policy enablers. Findings show that real-time data integration reduces CO2 and solid waste while enhancing investment confidence. A barrier-enabler matrix illustrates how technology-policy packages can reposition Circular Economy (CE) projects as low-risk, performance-driven assets. The study introduces a policy-technology pathway and discusses socio-economic and ethical implications. It concludes with a research agenda to embed UIS as standard urban practice, directly supporting Sustainable Development Goals (SDGs) 9, 11, 12, and 13.