196,019 research outputs found
Bioreactors for succinic acid production processes
No full textSuccinic acid (SA) has been recognized as one of the most important bio-based building block chemicals due to its numerous potential applications. Fermentation SA production from renewable carbohydrate feedstocks can have the economic and sustainability potential to replace petroleum-based production in the future, not only for existing markets, but also for new larger volume markets. Design and operation of bio-reactors play a key role. During the last 20 years, many different fermentation strategies for SA production have been described in literature, including utilization of immobilized biocatalysts, integrated fermentation and separation systems and batch, fed-batch, and continuous operation modes. This review is an overview of different fermentation process design developed over the past decade and provides a perspective on remaining challenges for an economically feasible succinate production processes. The analysis stresses the idea of improving the efficiency of the fermentation stage by improving bioreactor design and by increasing bioreactor performance.</p
Butanol production by clostridium acetobutylicum in a continuous packed bed reactor fed with cheese whey
No full textThis research work reports on the feasibility of bio-butanol production by fermentation of cheese whey in a continuous packed bed reactor (PBR). The anaerobic solventogenic bacterium Clostridium acetobutylicum DSM 792 was adopted for the fermentation processes and commercial cheese whey powder was adopted as substrate. The fermentation plant consisted of a PBR, liquid pumps, a thermostatic unit, and a pH control unit. The PBR was a 4 cm ID, 16 cm high glass tube with a 8 cm bed of 3 mm Tygon rings, as carriers. The pH ranged between 4.5 and 5.5, the dilution rate (D) between 0.4 h-1 and 0.64 h-1. The PBR feedstock was a solution of deproteinized cheese whey powder. Results show that the best performance (butanol productivity 2.66 g/Lh, butanol concentration 4.93 g/L, butanol yield 0.26 g/g, butanol selectivity of the overall solvents production 82%w) was at D=0.54 h-1. Copyright �� 2013, AIDIC Servizi S.r.l
RETRACTED: Continuous H-B-E fermentation by Clostridium carboxidivorans: CO vs syngas
No full textLeveraging renewable carbon-based resources for energy and chemical production is a promising approach to decrease reliance on fossil fuels. This entails a thermo/biotechnological procedure wherein bacteria, notably Clostridia, ferment syngas, converting CO or CO2 + H2 into Hexanol, Butanol and Ethanol (H-B-E fermentation). This work reports of Clostridium carboxidivorans performance in a stirred tank reactor continuously operated with respect to the gas and the cell/liquid phases. The primary objective was to assess acid and solvent production at pH 5.6 by feeding pure CO or synthetic syngas under gas flow differential conditions. Fermentation tests were conducted at four different dilution rates (DL) of the fresh medium in the range 0.034-0.25 h-1. The fermentation pathways of C. carboxidivorans were found to be nearly identical for both CO and syngas, with consistent growth and metabolite production at pH 5.6 within a range of dilution rates. Wash-out conditions were observed at a DL of 0.25 h-1 regardless of the carbon source. Ethanol was the predominant solvent produced, but a shift towards butanol production was observed with CO as the substrate and towards hexanol production with synthetic syngas. In particular, the maximum cell concentration (0.5 gDM/L) was obtained with pure CO at DL 0.05 h-1; the highest solvent productivity (60 mg/L*h of total solvent) was obtained at DL 0.17 h-1 by using synthetic syngas as C-source. The findings highlight the importance of substrate composition and operating conditions in syngas fermentation processes. These insights contribute to the optimization of syngas fermentation processes for biofuel and chemical production
Butanol production by bioconversion of cheese whey in a continuous packed bed reactor
No full textButanol production by Clostridium acetobutylicum DSM 792 fermentation was investigated. Unsupplemented cheese whey was adopted as renewable feedstock. The conversion was successfully carried out in a biofilm packed bed reactor (PBR) for more than 3. months.The PBR was a 4cm ID, 16cm high glass tube with a 8cm bed of 3mm Tygon rings, as carriers. It was operated at the dilution rate between 0.4h-1 and 0.94h-1.The cheese whey conversion process was characterized in terms of metabolites production (butanol included), lactose conversion and biofilm mass. Under optimized conditions, the performances were: butanol productivity 2.66. g/Lh, butanol concentration 4.93. g/L, butanol yield 0.26. g/g, butanol selectivity of the overall solvents production 82. wt%. �� 2013 Elsevier Ltd
Efficient succinic acid production from high-sugar-content beverages by Actinobacillus succinogenes
No full textThis study presents the production of succinic acid (SA) by Actinobacillus succinogenes using high-sugar-content beverages (HSCBs) as feedstock. The aim of this study was the valorization of a by-product stream from the beverage industry for the production of an important building block chemical, such as SA. Three types of commercial beverages were investigated: fruit juices (pineapple and ace), syrups (almond), and soft drinks (cola and lemon). They contained mainly glucose, fructose, and sucrose at high concentration—between 50 and 1,000 g/L. The batch fermentation tests highlighted that A. succinogenes was able to grow on HSCBs supplemented with yeast extract, but also on the unsupplemented fruit juices. Indeed, the bacteria did not grow on the unsupplemented syrup and soft drinks because of the lack of indispensable nutrients. About 30–40 g/L of SA were obtained, depending on the type of HSCB, with yield ranging between 0.75 and 1.00 gSA/gS. The prehydrolysis step improved the fermentation performance: SA production was improved by 6–24%, depending on the HSCB, and sugar conversion was improved of about 30–50%
A novel integrated fermentation/recovery system for butanol production by <i>Clostridium acetobutylicum</i>
No full textIntensive butanol production was carried out by immobilized cells of Clostridium acetobutylicum in a novel continuous fermentation system. The fermentation system consisted of four packed bed biofilm reactors (PBBR) connected in series. The novelty of the proposed system is: i) the use of a novel stagewise simulated moving bed (SMB) design/operational mode; ii) the integration of the reaction and the product recovery sections. The SMB operational mode was accomplished by equipping the PBBR with manifolds and time-actuated switching valves. PBBR integration with the product recovery section was also tested. An adsorption column was operated between the 3rd and 4th reactor of the series.The tuning of the PBBR system overall dilution rate (DOV) allowed to maximize: i) sugar conversion (DOV <0.150 h−1); ii) butanol concentration (0.650 h−1<DOV<0.900 h-1); iii) butanol productivity (13.0 g/Lh at DOV=0.900 h-1).The PBBR system was upgraded by integrating it with an in-line adsorption column and it guaranteed a twofold increase in butanol productivity (up to 22 g/Lh) and an average butanol concentration close to 24.0 g/L
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