Hydrodynamic analysis of full-scale in-situ biogas upgrading in manure digesters.

The addition of hydrogen to anaerobic digesters is an emerging technique for the sustainable upgrading of biogas to biomethane with renewable electricity. However, it is critically dependent on the effective gas-liquid transfer of hydrogen, which is a sparingly soluble gas. Very little is known about the impact of liquid and gas flow and bubble size on gas-liquid transfer during H injection in full-scale anaerobic digesters.

Cellulolytic and Xylanolytic Microbial Communities Associated With Lignocellulose-Rich Wheat Straw Degradation in Anaerobic Digestion.

The enzymatic hydrolysis of lignocellulosic polymers is generally considered the rate-limiting step to methane production in anaerobic digestion of lignocellulosic biomass. The present study aimed to investigate how the hydrolytic microbial communities of three different types of anaerobic digesters adapted to lignocellulose-rich wheat straw in continuous stirred tank reactors operated for 134 days. Cellulase and xylanase activities were monitored weekly using fluorescently-labeled model substrates and the enzymatic profiles were correlated with changes in microbial community compositions based on 16S rRNA gene amplicon sequencing to identify key species involved in lignocellulose degradation.

Stick or leave - Pushing methanogens to biofilm formation for ex situ biomethanation.

Biomethanation exploits the ability of methanogenic archaea to convert CO and renewable H from electrolysis to biomethane. Biofilm reactors are promising for biomethanation scale-up due to high CH productivity and low energy input for H gas-liquid mass transfer. Effects of operational conditions on biofilm dynamics remain largely uncharacterized but may increase reactor potentials further.