Innovative Ex-situ Biological Biogas Upgrading Using Immobilized Biomethanation Bioreactors Combined With Micro Sorbents

Biogas upgrading enhances energy value by increasing methane content. This study investigates an ex-situ biological upgrading approach using immobilized biomethanation bioreactors (IBBRs) with micro sorbents. Microporous organic polymers (MOPs: XDV1, XDV3) and powdered activated carbon (PAC) were incorporated into hydrophilic polyurethane (HPU) matrices to improve H₂ and CO₂ adsorption, enhancing hydrogenotrophic methanogenesis. Semi-batch and continuous lab-scale IBBRs were tested to assess the impact of gas recirculation and micro sorbents on methane production, H₂ consumption, and CO₂ removal. XDV1 exhibited the highest CH₄ enhancement due to superior gas adsorption capacity. Reducing recirculation lowered methane yield, but MOPs-alginate reactors achieved the highest CH₄ (83%), surpassing PAC-based systems. Hydrogen consumption was highest in MOPs-alginate reactors, confirming enhanced gas transfer efficiency. These results highlight micro sorbents as an effective tool for optimizing biomethanation, offering a scalable solution for biogas valorization.