Bio-integrated carbon capture and utilization: at the interface between capture chemistry and archaeal CO reduction.

Carbon capture and utilization (CCU) covers an array of technologies for valorizing carbon dioxide (CO). To date, most mature CCU technology conducted with capture agents operates against the CO gradient to desorb CO from capture agents, exhibiting high energy penalties and thermal degradation due to the requirement for thermal swings. This Perspective presents a concept of Bio-Integrated Carbon Capture and Utilization (BICCU), which utilizes methanogens for integrated release and conversion of CO captured with capture agents.

Dose-dependent effects of sodium dodecyl sulfate and hydrogen peroxide treatments on methane emission from pig manure during storage.

Mitigation of methane (CH) emissions from slurry pits within pig barns can be achieved through treatment of residual slurry left after frequent flushing of the slurry pits. In this study, dosages of additives such as sodium dodecyl sulfate (SDS) and hydrogen peroxide (HO) were optimized to achieve reduction in CH emissions from residual pig slurry during storage. In addition, the effects on emissions when both the treatments were combined and the effects of SDS treatment on slurry acidified with sulfuric acid (HSO) were studied in order to reduce CH and ammonia (NH) emissions from residual pig slurry storage.

Relevance of extracellular electron uptake mechanisms for electromethanogenesis applications.

Electromethanogenesis has emerged as a biological branch of Power-to-X technologies that implements methanogenic microorganisms, as an alternative to chemical Power-to-X, to convert electrical power from renewable sources, and CO into methane. Unlike biomethanation processes where CO is converted via exogenously added hydrogen, electromethanogenesis occurs in a bioelectrochemical set-up that combines electrodes and microorganisms. Thereby, mixed, or pure methanogenic cultures catalyze the reduction of CO to methane via reducing equivalents supplied by a cathode.

Exploring increased hydraulic retention time as a cost-efficient way of valorizing residual biogas potential.

Effective substrate utilization with low residual methane yield in the digestate is crucial for the economy and sustainability of biogas plants. The composition and residual methane potential of 29 digestate samples from plants operating at hydraulic retention times of 13-130 days were determined to evaluate the economic viability of extended digestion. Considerable contents of fermentable fractions, such as cellulose (8-23%), hemicellulose (1-18%), and protein (13-22%), were present in the digestate dry matter.

Enhanced process control of trickle-bed reactors for biomethanation by vertical profiling directed by hydrogen microsensor monitoring.

Biomethanation is an emerging Power-to-X technology enabling CO valorisation to produce biomethane using renewable H. A promising reactor for facilitating biomethanation is the trickle bed reactor (TBR), however, these bioreactors are conventionally operated with a black-box approach, where the system is solely described by the input and output characteristics. This study employed a novel approach for process surveillance of internal dynamics in TBRs by installing multiple H microsensors along its vertical axis.

Effect of ultrasonic and electrokinetic post-treatments on methane yield and viscosity of agricultural digestate.

The impact of post-treatment of digestate prior to its recirculation to the digester has been evaluated with industrial-scale ultrasonication and electrokinetic treatment units. Residual methane yields of untreated digestate samples from four biogas plants varied between 99 and 134 ml/g of volatile solids (after 97 days of digestion). At the tested conditions (1.

Wood-Ljungdahl pathway utilisation during in situ H biomethanation.

Biogas production from organic waste is a waste-to-energy technology with the potential to contribute significantly to sustainable energy production. Upgrading of biogas using in situ biomethanation with hydrogen has the potential for surplus electricity storage, and delivery of biogas with a methane content of >90%, allowing for easier integration into the natural gas grid, as well as conversion to other products. Microbial communities in biomethanation reactors undergo changes, however, these changes are largely unexplored.

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.

Methane production from syngas using a trickle-bed reactor setup.

Syngas from gasification of waste biomass is a mixture of carbon monoxide (CO), carbon dioxide (CO), and hydrogen (H), which can be utilized for the synthesis of biofuels such as methane (CH). The aim of the study research work was to demonstrate how syngas could be methanated and upgraded to natural gas quality (biomethane) in a fed-batch trickle-bed reactor system using either manure - (AD-M) or sludge-based (AD-WW) inoculum as microbial basis. The methanated syngas had a high concentration of CO and did not fulfil the criteria for natural gas quality biomethane.

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.

How Low Can You Go: Methane Production of at Low CO Concentrations.

Autotrophic hydrogenotrophic methanogens use H/CO as sole carbon and energy source. In contrast to H, CO is present in high concentrations in environments dominated by methanogens e.g.

Parameters affecting acetate concentrations during in-situ biological hydrogen methanation.

Surplus electricity may be supplied to anaerobic digesters as H gas to upgrade the CH content of biogas. Acetate accumulation has been observed following H injections, but the parameters determining the degree of acetate accumulation are not well understood. The pathways involved during H consumption and acetate kinetics were evaluated in continuous lab reactors and parallel batch C experiments.

In-situ biogas upgrading with pulse H additions: The relevance of methanogen adaption and inorganic carbon level.

Surplus electricity from fluctuating renewable power sources may be converted to CH via biomethanisation in anaerobic digesters. The reactor performance and response of methanogen population of mixed-culture reactors was assessed during pulsed H injections. Initial H uptake rates increased immediately and linearly during consecutive pulse H injections for all tested injection rates (0.

Dynamic microbial response of sulfidogenic wastewater biofilm to nitrate.

Nitrate is one of the chemicals often added to wastewater to control hydrogen sulfide production by sulfate-reducing bacteria (SRB). While the effect of nitrate in various SRB pure cultures is well documented, the effect observed in mixed microbial communities is not consistent. This study investigates the response of mixed SRB communities to nitrate, by examining the changes in activity and community composition of sulfidogenic wastewater biofilm over a 10-day period with 10 mmol L(-1) nitrate exposure.