An Anaerobic Trickle-Bed Reactor Filled with Siporax™ as a Novel Approach for Biomethanation of Hydrogen and Carbon Dioxide

To broaden the application of biomethanation for energy storage and renewable integration, this study investigates the performance of a trickle-bed reactor (TBR) for hydrogen (H2) utilisation in biogas upgrading, using both pure Carbon dioxide (CO2) and biogas-derived CO2 as substrates for methane (CH4) production. Renewable sources such as wind and solar are inherently variable, increasing the need for scalable storage solutions. Converting surplus electricity into H2 and CH4 via biological methanation offers an efficient and safer alternative to direct H2 storage. By reducing CO2 produced by biogas plants, methanogenic archaea produce CH4, enabling H2 valorisation and enhanced biogas yields. This study demonstrates that TBR technology can achieve CH4 formation rates up to 15 L-CH4/L-reactor/day under optimised conditions. Siporax carrier material supported dense biofilm formation and effective gas–liquid mass transfer, facilitating high conversion efficiency. The system showed operational robustness, with rapid recovery after prolonged idle periods and stable production rates of 10–12 L-CH4/L/day. Wastewater was used as a realistic medium to assess reactor performance under complex, variable conditions. Reactor design focused primarily on enhancing gas–liquid mass transfer and supporting sustained microbial activity through adequate nutrient supply, ensuring sufficient buffer capacity to maintain pH stability. These results demonstrate the potential of TBR-based systems for high-rate, stable biomethanation and highlight their applicability in future energy infrastructures for integrating H2 through decentralised biogas upgrading.