Article

Hydrogen and Ethanol production from Glycerol-containing wastes discharged after biodiesel manufacturing process

Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Japan.
Journal of Bioscience and Bioengineering (Impact Factor: 1.88). 10/2005; 100(3):260-5. DOI: 10.1263/jbb.100.260
Source: PubMed

ABSTRACT

H2 and ethanol production from glycerol-containing wastes discharged after a manufacturing process for biodiesel fuel (biodiesel wastes) using Enterobacter aerogenes HU-101 was evaluated. The biodiesel wastes should be diluted with a synthetic medium to increase the rate of glycerol utilization and the addition of yeast extract and tryptone to the synthetic medium accelerated the production of H2 and ethanol. The yields of H2 and ethanol decreased with an increase in the concentrations of biodiesel wastes and commercially available glycerol (pure glycerol). Furthermore, the rates of H2 and ethanol production from biodiesel wastes were much lower than those at the same concentration of pure glycerol, partially due to a high salt content in the wastes. In continuous culture with a packed-bed reactor using self-immobilized cells, the maximum rate of H2 production from pure glycerol was 80 mmol/l/h yielding ethanol at 0.8 mol/mol-glycerol, while that from biodiesel wastes was only 30 mmol/l/h. However, using porous ceramics as a support material to fix cells in the reactor, the maximum H2 production rate from biodiesel wastes reached 63 mmol/l/h obtaining an ethanol yield of 0.85 mol/mol-glycerol.

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Available from: Yutaka Nakashimada
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    • "Biodiesel is a renewable, healthier, environmentally friendly and sustainable alternative for fossil fuels.[1] The global biodiesel market is estimated to reach 140 billion liters by 2016 and, with increasing annual growth, production would reach 159 billion liters by 2020.[2] Biodiesel is produced by transesterification of feedstock such as vegetable oil and animal fats, causing an increase in the cost of these raw materials.[3] To meet the increasing demand, waste generated from restaurants and the meat processing industry containing CONTACT Satinder Kaur Brar satinder.brar@ete.inrs.ca "
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    ABSTRACT: Valorization of crude glycerol (CG), a waste of biodiesel production process, was investigated for increased hydrogen production by co-culture system using Enterobacter aerogenes NRRL B-407 and Clostridium butyricum NRRL B-41122. The ability of E. aerogenes was evaluated as a replacement of expensive reducing agent to maintain anaerobic conditions for the growth of C. butyricum. The co-culture resulted in increased hydrogen production, reaching a maximum of 19.46 ± 0.95 mmol-H2/L-medium in comparison to monoculture of E. aerogenes (15.64 ± 0.47) and C. butyricum (17.44 ± 0.38) in the presence of reducing agent. The effect of inoculum ratio was investigated and hydrogen yield was 0.95 mmol-H2/mol-glycerol at 1:11 inoculum ratio with more than 85% of substrate utilization was comparable to other mixed and co-culture studies. In addition to hydrogen, value added by-products such as 1,3-propandiol, acetic acid, butyric acid and ethanol have also been produced. Co-culture indicated the possibility of valorization of CG as a stable functional consortium with higher conversion efficiency for increased hydrogen along with high value by-product production. Additionally, the study provided the evidence of medium composition controlled metabolic pathway shift during CG bioconversion. Valorization of low cost CG with efficient co-culture of hydrogen production can aid biodiesel in-house energy source.
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    • "In recent years, renewable energy sources have received growing interest due to an increasing concern about global warming issues and stricter environmental legislations. Bio-fuel production –biodiesel and biogas – has risen considerably due to its environmental benefits as an alternative to fossil fuels, for its favourable energy balance, and its lower greenhouse gases emission rate (Ito et al., 2005). "
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    ABSTRACT: The effect of adding crude glycerine during continuous sewage sludge anaerobic digestion was investigated under thermophilic and mesophilic temperatures. Addition of CGY at thermophilic temperature range showed a negative impact on stability and performance of the process, even at low doses. The extreme pH values of CGY, together with the rapid release of VFA, causes SS alkalinity fail to control pH drop. On the contrary, at mesophilic temperature range the process performs steadily, with 148% increase in methane production when CGY represented 1% v/v of the influent (27% of influent COD). Further CGY percentages did not show any added improvement; the biomass shift, due to a high C/N ratio, could explain this behaviour. Results suggested that CGY can be used as co-substrate of SS anaerobic digestion though, depending on the characteristics of CGY, and on operational conditions, different parameters should be taken into account to achieve a steady and consistent operation. Copyright © 2015 Elsevier Ltd. All rights reserved.
    No preview · Article · Oct 2015 · Bioresource Technology
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    • "The theoretical yield for each intermediary stage was calculated as a combination of the theoretical H 2 yields of pure glucose (4 mol H2 mol −1 glucose consumed ) and glycerol (1 mol H2 mol −1 glycerol consumed ), weighted by their respective proportions in the feeding mixture (Ito et al. 2005; Akutsu et al. 2009). DGGE profiles were aligned and analyzed with GelCompar II software (Applied Maths, Sint-Martens-Latem, Belgium), to obtain the matrix of relative band intensity according to band position. "
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    ABSTRACT: Hydrogen is a promising alternative as an energetic carrier and its production by dark fermentation from wastewater has been recently proposed, with special attention to crude glycerol as potential substrate. In this study, two different feeding strategies were evaluated for replacing the glucose substrate by glycerol substrate: a one-step strategy (glucose was replaced abruptly by glycerol) and a step-by-step strategy (progressive decrease of glucose concentration and increase of glycerol concentration from 0 to 5 g L(-1)), in a continuous stirred tank reactor (12 h of hydraulic retention time (HRT), pH 5.5, 35 °C). While the one-step strategy led to biomass washout and unsuccessful H2 production, the step-by-step strategy was efficient for biomass adaptation, reaching acceptable hydrogen yields (0.4 ± 0.1 molH2 mol(-1) glycerol consumed) around 33 % of the theoretical yield independently of the glycerol concentration. Microbial community structure was investigated by single-strand conformation polymorphism (SSCP) and denaturing gradient gel electrophoresis (DGGE) fingerprinting techniques, targeting either the total community (16S ribosomal RNA (rRNA) gene) or the functional Clostridium population involved in H2 production (hydA gene), as well as by 454 pyrosequencing of the total community. Multivariate analysis of fingerprinting and pyrosequencing results revealed the influence of the feeding strategy on the bacterial community structure and suggested the progressive structural adaptation of the community to increasing glycerol concentrations, through the emergence and selection of specific species, highly correlated to environmental parameters. Particularly, this work highlighted an interesting shift of dominant community members (putatively responsible of hydrogen production in the continuous stirred tank reactor (CSTR)) according to the gradient of glycerol proportion in the feed, from the family Veillonellaceae to the genera Prevotella and Clostridium sp., putatively responsible of hydrogen production in the CSTR.
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