eBioMeth

Biological methanation (BM) allows for the conversion of carbon dioxide (CO2) and dihydrogen (H2) into biomethane thanks to the activity of specific microbes. This process can be considered as fundamental to deal with the current climate challenge to reduce CO2 emissions and fossil energy use. While the world energy consumption is predicted to rise by nearly 50% between 2018 and 2050 according to the US Energy Administration (EIA), replacement of natural gas by sustainably produced biomethane is therefore a valuable fossil fuel alternative solution. With a methane content above 95%vol, biomethane obtained from biomass and/or the valorization of CO2 from industry is suitable as an energy carrier or transportation fuel. Biomethane has the advantage of being able to benefit from the same infrastructure that is currently used by natural gas; therefore, this is also a rapid solution.

BM happens during the last step of anaerobic digestion (biogas production from biomass, such as farmyard waste), yet little is still known about the microbes involved in this specific step. Indeed, to the best of our knowledge, information about which microbes are involved in this process, which functions do they perform exactly and what controls their abundance rates, activities, and interactions are missing. It has been observed that during BM, competition for substrates such as CO2 and H2 is high. For example, hydrogenotrophic Archaea producing CH4 compete with homoacetogenic bacteria producing acetate, leading to CH4 yield loss. A knowledge gap is also existing concerning the behaviour of the BM microbiome toward process operating conditions that can be used. Thus, difficulties are observed at the experimental scale to run an efficient (e.g., mesophilic) BM in terms of CO2 conversion rate, whereby there is a high biomethane concentration rate in the final produced gas with an acceptable flow, allowing potential large industrial application.
 

The main objective of this research project is to study the microbial community involved in the mesophilic BM, to generate new important knowledge towards future microbial engineering. To do so, eBioMeth will investigate the effect of different mesophilic BM operating conditions such as inoculum, hydraulic retention time, gas retention time and pH on the microbiome involved in the mesophilic conversion of CO2 and H2 and the resulting process performances. Microbial community structure, function and interactions will be characterised by 16S rRNA amplicon sequencing and metatranscriptomics. This work will be done with the view of identifying the key microbial actors and functions that provide optimal CO2 and H2 conversion into CH4.
 

With this insight, mesophilic BM operating conditions may be adapted in a near future to naturally engineer the microbial community toward the best adapted organisms for an efficient process and push biological methanation as a core microbial technology for the CO2 valorization and for renewable energy production.

The know-how developed in the framework of eBioMeth is of high interest as well to push forward and promote our Dense membrane Gas Capture technology developed at laboratory (5L) and pilot scale (2x 800 L reactors installed in a mobile container).