CIRCULAR BIOGAS SYSTEMS: INTEGRATING BIOMASS VALORIZATION AND RESOURCE RECOVERY TOWARD SUSTAINABLE BIOREFINERIES

Resumo

The transition toward low-carbon and resource-efficient systems demands new strategies for waste management and energy generation. Biogas production through anaerobic digestion represents a pivotal technology connecting renewable energy, waste reduction, and nutrient recycling within the circular economy framework. This review synthesizes findings from recent literature addressing how agricultural, agro-industrial, animal, and municipal biomass streams can be valorized for energy and material recovery. Key attention is given to co-digestion, pretreatment optimization, digestate utilization, CO2 valorization, and integration into biorefinery models. Evidence shows that coupling biogas production with by-product recovery such as biofertilizers, activated carbon, and CO2 utilization, enhances both environmental and economic sustainability. The analysis supports that biogas systems can evolve into multi-output biorefineries that close material loops and strengthen regional circular economy strategies.