1,720,989 research outputs found
Butanol Production from Leftover Beverages and Sport Drinks
No full textThe aim of this paper is twofold: (1) to identify an alternative disposal process for the industry of high-sugar-content beverages (HSCBs) and (2) to contribute to the study of butanol production from non-edible feedstocks. HSCBs were used as a renewable feedstock to produce butanol by Clostridium acetobutylicum DSM 792. Four types of commercial beverages were investigated: fruit juices (pineapple and pear), syrups (lemon and almond), soft drinks, and a sport drink. They contained high levels of sugar—between 50 and 1,000 g/L—mainly glucose, fructose, and sucrose. These sugars were also tested individually and in a mixture. The batch fermentation tests were characterized in terms of metabolite and cell production, and sugar conversion. C. acetobutylicum was able to grow on HSCBs supplemented with yeast extract and minerals. The tests on the sugars (alone or mixed) highlighted the predisposition of C. acetobutylicum to metabolize them and to produce butanol. The production rate of butanol (rB MAX) increased in the following order: glucose, fructose, and sucrose. The HSCB pre-hydrolysis improved the fermentation performance in terms of solvent production and sugar conversion (almost 100 %) because sucrose has been hydrolyzed. Under optimized conditions the butanol concentration and yield were—13.3 g/L, 0.16 g/g for pineapple juice; 12.8 g/L, 0.14 g/g for pear juice; 13.2 g/L, 0.19 g/g for lemon syrup; 13.8 g/L, 0.14 g/g for almond syrup; 13–14 g/L, 0.17–0.18 g/g for commercial soft drinks, and 5.9 g/L, 0.11 g/g for sport drinks. Among the beverages tested, the sport drinks gave the maximum butanol production rate of 12 g/L h.</p
Non-Thermal Plasma as a Biomass Pretreatment in Biorefining Processes
No full textClimatic changes and the growing population call for innovative solutions that are able to produce biochemicals by adopting environmentally sustainable procedures. The biorefinery concept meets this requirement. However, one of the main drawbacks of biorefineries is represented by the feedstocks’ pretreatment. Lately, scientific research has focused on non-thermal plasma, which is an innovative and sustainable pretreatment that is able to obtain a high sugar concentration. In the present review, literature related to the use of non-thermal plasma for the production of fermentable sugar have been collected. In particular, its sugar extraction, time, and energy consumption have been compared with those of traditional biomass pretreatments. As reported, on one hand, this emerging technology is characterized by low costs and no waste production; on the other hand, the reactor’s configuration must be optimized to reduce time and energy demand
Downstream Processes in a Microalgae Biorefinery: Cascaded Enzymatic Hydrolysis and Pulsed Electric Field as Green Solution
No full textMicroalgae are a promising source of valuable compounds, including proteins, pigments, lipids, vitamins, and ingredients for cosmetics and animal feed. Despite their potential, downstream processing remains a major bottleneck in microalgae biorefineries, particularly in achieving high extraction efficiency with low energy and chemical input. While several extraction methods exist, few balance efficiency with selectivity and sustainability. Recently, mild and selective techniques such as Pulsed Electric Field (PEF) and Enzymatic Hydrolysis (EH) have gained attention, both individually and in combination. This review provides the first comprehensive comparative analysis of PEF and EH, emphasizing their mechanisms of action, specific cellular targets, and potential for integration into a cascaded, wet-route biorefinery process. Studies involving PEF, EH, and their sequential application (PEF-EH and EH-PEF) are analyzed, focusing on microalgae species, operational conditions, and extraction yields. The advantages and challenges of each method, including compound selectivity, environmental impact, and economic feasibility, are critically evaluated. The goal is to gain insight into whether the synergistic use of PEF and EH can enhance the recovery of intracellular compounds while improving the overall sustainability and efficiency of microalgae-based bioprocessing
Biobutanol Production from Hexose and Pentose Sugars
No full textThe Acetone-Butanol-Ethanol (ABE) fermentation is receiving renewed interest as a way to upgrade renewable resources for the production of products with high added value as chemicals and fuels. Main pre-requisites of fermentation feedstocks are abundance and un-competitiveness with food sources and they are fulfilled by lignocellulosic biomass. This contribution reports about the characterization of the ABE fermentation by Clostridium acetobutylicum DSM 792 adopting sugars representative for hydrolysis products of lignocellulosic biomass: glucose, mannose, arabinose, and xylose. Batch fermentation tests with binary mixtures of sugars were performed to assess the possible crossed/coupled effects of the investigated sugars on the fermentation performances. The mass ratio of sugars in binary mixture tests was set at 1:1 and the total initial concentration was set at 60 g/L. The conversion process was characterized as a function of the time in terms of biomass, acids, and solvents concentrations as well as of pH and total organic compounds. The simultaneously fermentation of binary mixture of sugars enhances the conversion of the investigated sugars into butanol/solvents. The xylose fermentation appears to be improved when it is mixed with the investigated sugars
Continuous xylose fermentation by Clostridium acetobutylicum - Assessment of solventogenic kinetics
No full textThis work deals with the specific butanol production rate of Clostridium acetobutylicum using xylose - a relevant fraction of lignocellulosic feedstock for biofuel production - as carbon source. The tests were carried out in a CSTR equipped with a microfiltration unit. The dilution rate (D) ranged between 0.02 and 0.22h-1 and the ratio R between the permeate stream rate and the stream fed to the reactor ranged between 14% and 88%. The biomass present in the broth was identified as a heterogeneous cell population consisting of: acidogenic cells, solventogenic cells and spores. The results were processed to assess the concentration of acidogenic cells, solventogenic cells and spores. The specific butanol production rate was also assessed. The max butanol productivity was 1.3 gL-1h-1 at D=0.17h-1 and R=30%. A comparison between the results reported in a previous work carried out with lactose was made.</p
Combined antioxidant-biofuel production from coffee silverskin
No full textBiorefinery concept asks for an integrated processing approach to exploit all biomass components. The self-sustainability target may be approached if molecules characterized by high added value and fermentable sugars are produced simultaneously. In the present study, sequential (i) mild hydrothermal pretreatment to produce antioxidants and (ii) NaOH pretreatment to produce a fermentable sugar solution were carried out on coffee silverskin. Twenty-minute treatment and biomass to liquid ratio 1:30 (g mL−1) were identified as optimal operating conditions to extract bioactive compounds characterized by antioxidant activity (22.2 mgGAE/gCSS; 13.9 mgTE/gCSS). Twenty-minutes and biomass to liquid ratio of 1:20 (g mL−1) were identified as optimal operating conditions to maximize sugar recovery and ABE production (solvent yield YABE/Sugars and ABE productivity of 0.21 g g−1 and 0.12 g L−1 h−1 were obtained, respectively). The study marks the highly economic potential of the process aimed to exploit the CSS as feesdstock for antioxidant and biofuel production.</p
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
Butanol production by Clostridium acetobutylicum in a series of packed bed biofilm reactors
No full textThe continuous production of Acetone, n-Butanol and Ethanol (ABE) by immobilized cells of Clostridium acetobutylicum DSM 792 using glucose and lactose as carbon source is presented in this paper. The conversion process was successfully carried out for more than three months in 4 packed bed biofilm reactors (PBBRs) connected in series. The first PBBR of the series (fed with fresh medium) was kept under acidogenesis conditions and the three other PBBRs were kept under solventogenesis conditions.
Each PBBR was a glass tube (4 cm ID, 8 cm high) with a 4 cm-bed of 3 mm-Tygon rings as carriers. The PBBR system was fed with 100g/L of lactose medium. The fermentation process was characterized in terms of metabolite production (butyric and acetic acids, acetone, butanol, and ethanol), sugar conversion and mass of biofilm. The overall dilution rate (DTOT) was varied between 0.15 h-1 and 0.9 h-1 to assess the PBBR system performance as a function of DTOT. The best PBBR system performance under optimized conditions was: butanol productivity 9.2 g/Lh, butanol concentration 10.8 g/L, acetone concentration 2.4 g/L, ethanol concentration 1.8 g/L, selectivity of butanol with respect to all solvents 72%w. To the authors’ knowledge, these butanol productivity and concentration values are the highest in the literature on lactose/(cheese whey) fermentation.
An interpretation of the biofilm structure in the PBBR was put forward
Ultrasound-assisted dilute acid pretreatment of coffee silverskin for biorefinery applications
No full textCoffee silverskin (CSS) is an agro-food processing waste (AFW) largely produced in roasting factories at almost constant rate over the year. The CSS can be used as a source of fermentable sugars within a biorefinery approach for its exploitation. Pretreatment process and enzymatic hydrolysis are required to efficiently recovery monomeric fermentable sugars from AFWs such as CSS. Current research is focused on the selection of novel processes for biomass pretreatments able to provide effective lignin removal, to minimize the production of by-products that may inhibit the fermentation of the produced sugars, and to be cost saving with respect to conventional pretreatments. The aim of the present study was to investigate the effect of the ultrasound (US) assisted dilute acid pretreatment on the effective separation of lignin and polysaccharides of CSS. The effects of two operating conditions - biomass loading and sulphuric acid concentration - were studied to assess their effects on the sugar yields after enzymatic hydrolysis. The production of typical species that may inhibit the fermentation of the hydrolysate was monitored. Inhibitors like furfural, 5-hydroxymethyl furfural (HMF), ferulic and p-coumaric acid were present at concentrations lower than 1 mg/L after enzymatic hydrolysis of the pretreated CSS. As a result, the hydrolysate of US dilute acid pretreated CSS may be used for fermentation without detoxification ste
Continuous butanol production by Clostridium acetobutylicum in a series of packed bed reactors
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