Can biorefineries be fully circular? A life cycle thinking perspective on agro-industrial biorefineries

Agro-industrial biorefineries are central to the circular bioeconomy, but their circularity cannot be inferred solely from product recovery or process efficiency. Biorefineries integrating physicochemical pretreatments, biological conversion and extraction should be designed and assessed through a Life Cycle Thinking (LCT) perspective. Two major sources of non-circularity are contaminants present in biomass feedstocks and inhibitory or persistent compounds generated during processing. These compounds can impair enzymatic hydrolysis, anaerobic digestion, nutrient recovery, digestate quality and the safe reintegration of residual streams into agricultural soils. Although many unit operations have reached technological maturity, integrated assessments linking upstream decisions with downstream environmental performance remain limited. A fully circular biorefinery should therefore be defined by its ability to preserve residual-stream suitability for biological valorisation and safe environmental reintegration. Integrating Life Cycle Assessment, Material Flow Analysis, Substance Flow Analysis and Safe-and-Sustainable-by-Design provides a comprehensive framework for identifying trade-offs and supporting environmentally safe, resource-efficient biorefineries.