A novel biological process to upgrade biogas was developed and optimised during the current study. In this process, CO in the biogas and externally provided H were fermented under mesophilic conditions to volatile fatty acids (VFAs), which are building blocks of higher-value biofuels. Meanwhile, the biogas was upgraded to biomethane (CH >95%), which can be used as a vehicle fuel or injected into the natural gas grid. To establish an efficient fermentative microbial platform, a thermal (at two different temperatures of 70 °C and 90 °C) and a chemical pretreatment method using 2-bromoethanesulfonate were investigated initially to inhibit methanogenesis and enrich the acetogenic bacterial inoculum. Subsequently, the effect of different H:CO ratios on the efficiency of biogas upgrading and production of VFAs were further explored. The composition of the microbial community under different treatment methods and gas ratios has also been unravelled using 16S rRNA analysis. The chemical treatment of the inoculum had successfully blocked the activity of methanogens and enhanced the VFAs production, especially acetate. The chemical treatment led to a significantly better acetate production (291 mg HAc/L) compared to the thermal treatment. Based upon 16S rRNA gene sequencing, it was found that H-utilizing methanogens were the dominant species in the thermally treated inoculum, while a significantly lower abundance of methanogens was observed in the chemically treated inoculum. The highest biogas content (96% (v/v)) and acetate production were achieved for 2H:1CO ratio (v/v), with Acetoanaerobium noterae, as the dominant homoacetogenic hydrogen scavenger. Results from the present study can pave the way towards more development with respect to microorganisms and conditions for high efficient VFAs production and biogas upgrading.

The present study proposes a novel alternative method of the current biogas upgrading techniques by converting CO 2 (in the biogas) into valuable chemicals (e.g., volatile fatty acids) using H 2 as energy source and acetogenic mixed culture as biocatalyst. The influence of thermal treatment (90°C) on the inhibition of the methanogenic archaea and enriching the acetogenic bacteria in different inocula (mesophilic and thermophilic) was initially tested.The most efficient inoculum that achieved the highest performance through the fermentation process was further used to define the optimum H 2 /CO 2 gas ratio that secures maximum production yield of chemicals and maximum biogas upgrading efficiency. In addition, 16S rRNA analysis of the microbial community was conducted at the end of the experimental period to target functional microbes. The maximum biogas content (77% (v/v)) and acetate yield (72%) were achieved for 2H 2 :1CO 2 ratio (v/v), with Moorella sp. 4 as the most dominant thermophilic acetogenic bacterium.

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High efficient ethanol and VFAs production from gas fermentation: effect of acetate, gas and inoculum microbial composition. Biomass & Bioenergy, 105,[32][33][34][35][36][37][38][39][40]. https://doi. Abstract 21In bioindustry, syngas fermentation is a promising technology for biofuel production 22 without the use of plant biomass as sugar-based feedstock. The aim of this study was to 23 identify the optimal conditions for high efficient ethanol and volatile fatty acids (VFAs) 24 production from synthetic gas fermentation. Therefore, the effect of different gases 25 (pure CO, H 2 , and a synthetic syngas mixture), media (acetate medium and acetate-free 26 medium), and biocatalyst (pure and mixed culture) were studied. Acetate was the most 27 dominant product independent of inoculum type. The maximum concentration of 28 volatile fatty acids and ethanol was achieved by the pure culture (Clostridium 29 ragsdalei). Depending on the headspace gas composition,VFAs concentrations were up 30 to 300% higher after fermentation with Clostridium ragsdalei compared to mixed 31 culture.The addition of acetate has a negative impact on the VFAs formation with a 32 varying degree depending on gas compositions. 33 pathway [6]. Several mesophilic pure cultures especially within the species Clostridium 66 have been used for syngas fermentation [7]. Prominent among these is Clostridium 67 ragsdalei, which has been successfully used for syngas fermentation [8,9]. However 68 still important challenges need to be addressed before commercial application. Gas-69 iquid mass transfer limitations, syngas quality, microbial catalysts and product recovery 70 are the major issues to be addressed in order to make syngas fermentation more 71 economically feasible [10]. 72Recently mixed culture fermentation has gained more attention due to several 73 advantages compared to the pure culture, such as process robustness during continuous 74 processes and no need for highly sterile conditions [11]. However, systematic 75 comparison of pure and mixed culture syngas fermentation to alcohols and/or acids, 76 which could permit developing efficient biofuels and biochemicals processes, has not be 77 made so far. 78In addition to the microbial catalysts, syngas composition in terms of H 2 /CO ratio is 79 also an important factor that significantly affects the output of the syngas fermentation 80 process [12]. It has been recently reported that some Clostridia species could further 81 reduce the volatile fatty acids (VFAs) to their corresponding alcohols by using syngas 82 as electron donor [13]. Thus, it is of importance to investigate the influence of precence 83 of VFAs (e.g., acetate) on the gas fermentation processes [14]. 84Based on the points highlighted above, the main objective of this study was to identify 85 the optimal conditions (media, gas compositions andmicrobial catalyst) for high 86 efficient alcohol and VFAs production from synthetic gas fermentation. Moreover 87 129 Morpholino) ethanesulfonic acid sodium salt) buffer solution, vitamin and...

An Au/Fe(III)ClTPP/p-Si/Al heterojunction diode was constructed. The I-V characteristics of the sensor under dark and illumination conditions were studied before and after γ-irradiation. C-V measurements were also carried out at 1 MHz before and after γ-irradiation. Two conduction mechanisms are operating in the device depending on the applied potential. Thermionic emission conduction is operating up to 0.6 V and space charge limited current conduction is operating at voltages >0.6 V. The rectification ratio, built-in potential and density of defect states in the interfacial layer increase with increasing the irradiation dose. Increasing the irradiation dose decreases the quality factor, the dark current, the capacitance at zero bias potential and the carrier density in the depletion region. These changes are attributed to an increase in the density of defect states in the interfacial layer and energy gap of a semiconductor upon γ-irradiation.

Oil spills are a significant threat to the marine ecosystem that requires immediate removal from the oceanic environment. Many technologies have been employed to clean up oil spills. Of these, adsorption has scored a prominent success due to the high efficiency, economic viability, environmental friendship, and ease of application. The utilization of agricultural waste to produce biosorbents have been considered as an ecofriendly and efficient approach for removing oil. Thus, a new low-cost oil adsorbent was prepared via esterification of the wheat straw (Str) with a hydrophobic benzoyl group, the resulting copolymer (Str-co-Benz) was characterized by FTIR, TGA, DSC, and SEM and used at laboratory scale. The oil spill cleanup process was conducted using a crude oil-natural seawater system under different adsorption conditions such as oil concentration, adsorbent dose, agitation time and speed. Equilibrium studies were performed to determine the capacity of the prepared materials for crude oil adsorption. Langmuir and Freundlich adsorption models were used to describe the experimental isotherms. The reliability of the data was examined and evaluated via application of response surface methodology program. The results showed that oil adsorption followed a pseudo-second-order kinetic model and fitted well with Langmuir model with a maximum adsorption capacity of 10.989 and 12.786 g/g for Str and (Str-co-Benz), respectively. Overall, the modified wheat husk is an effective platform for removing oil from marine ecosystems due to low cost, biodegradability, simple synthesis and fast removal. Moreover, the resulted solid can be used as a fuel in some industrial processes such as steam boilers and brick production incinerators.

Background: Polymerase chain reaction (PCR) is the benchmark in diagnosing of corona virus disease. It takes at least 4 hours. Multiple studies reported that rapid antigen test could be used. Their role in diagnosing corona virus disease 2019 (COVID-19) is questionable. This study was conducted to assess the accuracy of rapid antigen test in

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