Scale up study of a thermophilic trickle bed reactor performing syngas biomethanation

Microbial community development during syngas methanation in a trickle bed reactor with various nutrient sources

“…Carrier samples taken in startup, period 1 and period 2A were sequenced without replicates, due to lack of extracted material reactor), which could have been caused by factors such as (i) the presence of both methylotrophic and hydrogenotrophic methanogenesis, since hydrogenotrophic methanogens mainly utilise hydrogen during syngas methanation but acetate can be produced via acetogenesis from CO, requiring acetoclastic methanogens for further conversion to methane and (ii) high abundance of order Methanobacteriales, as several studies on biomethanation in TBR have shown enrichment of methanogens within this order, such as genus Methanobacterium and Methanothermobacter, indicating importance for biomethanation in such reactors (Aryal et al 2021;Sposob et al 2021). Previous studies on syngas methanation in TBR have used inoculum from biogas processes operating with manure (Aryal et al 2021) and sludge (Grimalt-Alemany et al 2020;Figueras et al 2021;Li et al 2021), or a mix of both (Asimakopoulos et al 2020a), as well as syngas-or H 2 -enriched cultures (Asimakopoulos et al 2020b(Asimakopoulos et al , 2021Sieborg et al 2020) and defined cultures comprising just a few organisms (Kimmel et al 1991;Klasson et al 1992). No obvious trends have emerged that some inocula are more suitable than others.…”

“…For biological CO 2 methanation, including TBR, several different non-defined cheap nutrient sources, such as digestate from different biogas processes and manure, have been evaluated and have been shown to be economically feasible for both mesophilic and thermophilic operation (for reviews, see Sposob et al 2021;Wegener Kofoed et al 2021). However, many previous studies have used defined nutrient medium for syngas methanation (Grimalt-Alemany et al 2018;Asimakopoulos et al 2020aAsimakopoulos et al , 2021Grimalt-Alemany et al 2020) and only a few have evaluated non-defined nutrients sources, mostly in batch systems (Ács et al 2019;Aryal et al 2021). To our knowledge, only one previous study has used a undefined nutrient source during continuous operation of a TBR for syngas methanation (Figueras et al 2021).…”

Microbial Enrichment Techniques on Syngas and CO2 Targeting Production of Higher Acids and Alcohols

“…Microbial communities present a series of benefits derived from their inherent microbial diversity and functional redundancy; however, their high complexity also constitutes one of their major limitations as they often result in decreased product selectivity, requiring further development of community management strategies. So far, application of MMC has been exceptionally promising for the production of methane and acetic acid [ 8 , 9 , 10 , 11 , 12 ], while it has also shown high potential for ethanol production, especially when the medium is supplemented with acetic acid [ 11 , 12 , 13 ]. Production of molecules with higher carbon atoms is mainly investigated in processes based on pure, wild or engineered microbial strains or co-cultures [ 14 , 15 , 16 , 17 ], while there is an emerging interest also in MMC [ 18 , 19 , 20 , 21 ].…”

Pilot-scale study of biomethanation in biological trickle bed reactors converting impure CO2 from a Full-scale biogas plant

“…Recent studies from Tsapekos et al (2021) and Cheng et al (2022) used a semi pilot-scale trickle bed reactor with a packed volume of 68 L and 35 L. However, the focus in both studies was on the microbial communities applying metagenomics and the reactors were operated at low gas feed rates. Asimakopoulos et al (2021) conducted a scale up study for syngas biomethanation in semi-pilot trickle bed reactor with a packed volume of 5 L. They reported 100 % H 2 conversion and CH 4 production capacity of 5.7 Nm 3 m − 3 d − 1 at a gas retention time (GRT) of 0.6 h.…”