Advancing Decarbonisation through Sustainable Solid-State Digestate Management in Biogas Systems: Economic, Agronomic, and Environmental Implications

This study explores the role of solid-state digestate management in biogas systems as a decarbonisation strategy within the circular bioeconomy. A meta-synthesis of 45 Scopus-indexed studies reveals that, sustainable digestate utilization enhances bioenergy efficiency, soil health, and biodiversity, while simultaneously reducing Green House Gas (GHG) emissions through carbon sequestration. Key agronomic benefits include nutrient recycling, enhanced soil fertility, and reduced dependency on synthetic fertilizers, contributing to regenerative agricultural practices. Despite its potential, challenges such as contamination risks, policy gaps, and infrastructure limitations hinder widespread adoption, particularly in emerging economies. Developed regions employ advanced valorization technologies and regulatory frameworks, whereas low-cost, scalable solutions offer promise for resource-limited settings. Integrating biochar with solid-state digestate further enhances carbon storage, soil resilience, and microbial safety, supporting sustainable agroecosystems. Policy recommendations highlight the need for harmonized quality standards, financial incentives, and capacity-building initiatives to ensure Digestate's safe and effective utilization. This research underscores its role in circular agriculture, fostering economic and environmental sustainability in biogas systems by positioning solid-state digestate as a key enabler of the bioenergy transition.