Research project: Effective mass transfer of hydrogen into digester mixed liquor for biomethanisation of biogas CO2

The mass transfer of H2 from the gaseous phase into the digester liquor has been identified as the limiting step in the biochemical conversion of H2 and CO2 into CH4. This research project aims to address this by developing a robust system for H2 injection into food waste digesters to achieve in-situ gas upgrading and efficient feedstock carbon utilisation.

Objectives

• To select a hollow-fibre membrane (HFM) diffuser suitable for use in a digester liquor
• To quantify the mass transfer efficiency of the device and to size it in relation to the anticipated H2 demand within the digester
• To assess the kinetics of H2 uptake in a hydrogenotrophic-adapted digestate derived from food waste treatment
• To assess any inhibition as a result of disruption of syntrophy in the system biology
• To test the diffuser system in a modified continuously-stirred tank reactor (CSTR) digester
• To operate the digester continuously with a food waste and H2 feed with the objective of producing an output concentration equal to natural gas (>95% CH4)