Ex-situ biomethanation for CO2 valorization: State of the art, recent advances, challenges, and future prospective.

Ex-situ biomethanation is an emerging technology that facilitates the use of surplus renewable electricity and valorizes carbon dioxide (CO2) for biomethane production by hydrogenotrophic methanogens. This review offers an up-to-date overview of the current state of ex-situ biomethanation and thoroughly analyzes key operational parameters affecting hydrogen (H2) gas-liquid mass transfer and biomethanation performance, along with an in-depth discussion of the technical challenges. To the best of our knowledge, this is the first review article to discuss microbial community structure in liquid and biofilm phases and their responses after exposure to H2 starvation during ex-situ biomethanation. In addition, future research in areas such as reactor configuration and optimization of operational parameters for improving the H2 mass transfer rate, inhibiting opportunistic homoacetogens, integration of membrane technology, and use of conductive packing material is recommended to overcome challenges and improve the efficiency of ex-situ biomethanation. Furthermore, this review presents a techno-economic analysis for the future development and facilitation of industrial implementation. The insights presented in this review will offer useful information to identify state-of-the-art research trends and realize the full potential of this emerging technology for CO2 utilization and biomethane production.

Emergency unit assessment of seven tertiary hospitals in Nepal using the WHO tool: a cross-sectional study.

BACKGROUND: In 2021, the Nepal national emergency care system's assessment (ECSA) identified 39 activities and 11 facility-specific goals to improve care. To support implementation of the ECSA facility-based goals, this pilot study used the World Health Organization's (WHO) Hospital Emergency Unit Assessment Tool (HEAT) to evaluate key functions of emergency care at tertiary hospitals in Kathmandu, Nepal. METHODS: This cross-sectional study used the standardized HEAT assessment tool. Data on facility characteristics, human resources, clinical services, and signal functions were gathered via key informant interviews conducted by trained study personnel. Seven tertiary referral centers in the Kathmandu valley were selected for pilot evaluation including governmental, academic, and private hospitals. Descriptive statistics were generated, and comparative analyses were conducted. RESULTS: All facilities had continuous emergency care services but differed in the extent of availability of each item surveyed. Academic institutions had the highest rating with greater availability of consulting services and capacity to perform specific signal functions including breathing interventions and sepsis care. Private institutions had the highest infrastructure availability and diagnostic testing capacity. Across all facilities, common barriers included lack of training of key emergency procedures, written protocols, point-of-care testing, and ancillary patient services. CONCLUSION: This pilot assessment demonstrates that the current emergency care capacity at representative tertiary referral hospitals in Kathmandu, Nepal is variable with some consistent barriers which preclude meeting the ECSA goals. The results can be used to inform emergency care development within Nepal and demonstrate that the WHO HEAT assessment is feasible and may be instructive in systematically advancing emergency care delivery at the national level if implemented more broadly.

Elucidation of microbial interactions, dynamics, and keystone microbes in high pressure anaerobic digestion.

High-pressure anaerobic digestion (HPAD) is a promising technology for producing biogas enriched with high methane content in a single-step process. To enhance HPAD performance, a comprehensive understanding of microbial community dynamics and their interactions is essential. For this, mesophilic batch high-pressurized anaerobic reactors were operated under 3 bars (H3) and 6 bars (H6). The experimental results showed that the effect of high-pressure (up to 6 bar) on acidification was negligible while methanogenesis was significantly delayed. Microbial analysis showed the predominance of Defluviitoga affiliated with the phylum Thermotogae and the reduction of Thiopseudomonas under high-pressure conditions. In addition, the microbial cluster pattern in H3 and H6 was significantly different compared to the CR, indicating a clear shift in microbial community structure. Moreover, Methanobacterium, Methanomicrobiaceae, Alkaliphilus, and Petrimonas were strongly correlated in network analysis, and they could be identified as keystone microbes in the HPAD reactor.

Nanoparticle-associated single step hydrogen fermentation for the conversion of starch potato waste biomass by thermophilic Parageobacillus thermoglucosidasius.

In the present study, starch-based potato peel waste biomass (PWB) was utilized as a potential substrate for hydrogen production via dark fermentation by the thermophillic amylase producing strain Parageobacillus thermoglucosidasius KCTC 33548. Supplementation of Fe3O4 nanoparticles (300 mg/L) led to a 4.15-fold increase in hydrogen production as compared to the control. The addition of optimized concentrations of both Fe3O4 nanoparticles (300 mg/L) and L-cysteine (250 mg/L) during hydrogen fermentation using pure starch and PWB generated maximum cumulative hydrogen yields of 167 and 71.9 mL with maximum production rates of 2.81 and 1.26 mL/h, respectively. Further, the correlation between Fe3O4 and the expression of hydrogenase isoforms and the related hydrogenase activity was explored. The possible mechanisms of the action of Fe3O4 on enhanced hydrogenase activity and hydrogen production was elucidated. To our knowledge, there are no such studies reported on enhanced hydrogen production from PWB in a single step.