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.
Background: Burullus Lake has received a great attention because of its environmental and economic importance for being a significant source of fish production in Egypt. It is subjected to many of environmental changes due to the huge amount of discharges originated from different sources as well as many human activities. The Nile tilapia (Oreochromis niloticus) is an abundant sedentary fish present in the most Egyptian lakes, Nile River, and ponds. The study was designed to evaluate some metal pollution in Burullus Lake. Results: The values of heavy metals (Mn, Zn, Fe, Ni, Cu, and Pb) were measured in lake water and muscles of O. niloticus fish during winter and summer 2014. Water samples were collected from six sampling sites, while fish samples were collected from the three sectors (eastern, middle, and western) of the lake. The mean values of heavy metals (Mn, Zn, Fe, Ni, Cu, and Pb) in surface water of Burullus Lake during winter and summer for the year 2014 were 1.09, 10.50, 29.38, 6.87, 2.05, and 5.98 μg/L, respectively, whereas the annual means of heavy metals (Mn, Zn, Fe, Ni, Cu, and Pb) in the muscles of O. niloticus fish were 0.68, 4.70, 10.62, 0.52, 0.39, and 0.46 μg/g wet wt., respectively. Conclusions: In lake water, Mn was the lowest concentration of the six sampling sites, while Fe was the highest concentration, whereas in fish muscles, Cu recorded the lowest concentration of the three sectors, while Fe was the highest concentration. The southern part of Burullus Lake had the highest heavy metal values as it influenced by the discharge of massive amounts of domestic sewage as well as agricultural and industrial effluents. The accumulation of heavy metals in fish muscles of the three sectors showed different patterns. Generally, the values of metals in the fish muscles were accepted by the international legislation limits and are safe for human consumption.
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.
This study aims to assess the land degradation risk in the governorate by using Geographical Information System (GIS) technique. The preliminary landforms of the area were defined by using remote sensing data. The area includes flood plain, lacustrine plain and marine plain. A total of 18 soil profiles representing different mapping units were studied. Thirty six soil samples were collected for laboratory analysis. The soil properties of bulk density and electrical conductivity (EC) were attached to the different landforms. The thematic layers of these properties were created in Arc-GIS 10.2 software using the spatial analysis function and then these layers were matched together to assess the soil degradation. The obtained results revealed that the high risk of physical (i.e. soil compaction) and chemical vulnerability (i.e. salinization) covered an area of 86.02 km 2 (12.83%) and 2.28 km 2 (0.34%), respectively in the surface soil layers. The land degradation hazard in the surface layers due to soil compaction was moderate to very high, whereas the degree of salinization was low to high. Regarding to the subsurface soil layers, the high risk of physical degradation and chemical degradation covered an area of 127.8 km 2 (19.06%) and 10.6 km 2 (1.58%), respectively. The land degradation hazard due to soil compaction in the subsurface layers was moderate to high, whereas the degree of salinization was low to very high.
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...
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