High-Performance Biogas Upgrading Using a Biotrickling Filter and Hydrogenotrophic Methanogens

Area of Science:

• Biotechnology
• Environmental Engineering
• Microbial Engineering

Background:

• Biogas upgrading is crucial for utilizing methane (CH₄) from anaerobic digestion.
• Conventional methods face challenges in efficiency and cost-effectiveness.
• Biotrickling filters offer a promising biological approach for gas treatment.

Purpose of the Study:

• To develop and evaluate a biotrickling filter (BTF) for efficient biogas upgrading.
• To investigate the use of hydrogen (H₂) addition to reduce carbon dioxide (CO₂) and enhance methane (CH₄) production.
• To assess the performance and microbial community dynamics within the BTF.

Main Methods:

• A bench-scale biotrickling filter (BTF) was constructed and packed with polyurethane foam (PUF).
• The BTF was inoculated with hydrogenotrophic methanogens and fed a gas mixture of H₂ and CO₂ (80:20% vol.).
• Methane production rates, H₂ and CO₂ removal efficiencies, and microbial viability/composition were analyzed.

Main Results:

• The BTF achieved maximum CH₄ production rates of 38 m³CH₄ m⁻³reactor day⁻¹, which is 5-30 times faster than other bioreactors.
• High removal efficiencies were recorded: 83% for H₂ and 96% for CO₂.
• Microbial analysis indicated lower methanogen viability and abundance towards the filter exit, suggesting room for optimization.

Conclusions:

• The developed BTF demonstrates highly efficient biogas upgrading with rapid methane production rates.
• Efficient mass transfer and high methanogen density contribute to the observed performance.
• Optimizing methanogen density and activity holds potential for further enhancing biogas upgrading rates.