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


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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    • "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.
    Applied Microbiology and Biotechnology 08/2015; 99(19). DOI:10.1007/s00253-015-6832-6 · 3.34 Impact Factor
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    • "Anaerobic bacteria are mostly researched for their increased hydrogen production rate and ability to work on a wide range of substrates. The anaerobic bacteria belonging to Clostridium species are typically used for bioconversion of carbohydrate to hydrogen, acetate, butyrate, CO 2 and organic solvents.[29] Hydrogen production follows the butyrate and acetate pathway, in the presence of hydrogenase enzyme at a suitable butyrate/acetate ratio to produce 6 mol of hydrogen from two moles of glucose. "
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    ABSTRACT: In coming years, the generation of organic wastes will exceed 250 billion tonnes worldwide. The organic wastes offer plentiful source of readily available and inexpensive substrates for fermentative hydrogen production. A sustainable approach for hydrogen production from various methods, such as photo-, dark fermentation and sequential two-stage has significant advantages to complement traditional process. During hydrogen fermentation, defined, well characterized and composite microorganisms are studied. Substantial research efforts have been carried out to increase hydrogen production by using co-culture system, which offers advantage of increased H2 yield and production rate in comparison to mono-culture. Concept of co-culture system is a simple step of mixing together different microbial strains for improving the individual properties that other strain lacks. Co-culture system is a cost-effective, which potentially eliminates pre-treatment step and avoids use of expensive reducing agent. By eliminating these two steps, the overall process cost can be reduced without negotiating the hydrogen yield. Co-culture system directly hydrolyzes complex organic substrates into fermentable sugar with 94.1% improved yield in comparison to mono-culture. Co-culture offers various advantages, example, reduction in lag phase, resistance to environmental fluctuations and provides stability with uninterrupted hydrogen production rate, which is 8 times in comparison to mono-culture. Co-culture system of hydrogen production is also an alternative effluent treatment method with 60% reduction in COD level and can be easily integrated into pilot-scale to achieve continuous H2 production. The elaboration on co-culture system suggests a huge potential of hydrogen production using complex organic wastes with viable application towards industrialization.
    Environmental Technology 06/2015; DOI:10.1080/21622515.2015.1068381 · 1.56 Impact Factor
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    • "Crude glycerol from biodiesel manufacturing plant may contain up to 25%(w/w) methanol[22] and from different studies it has been concluded that biodiesel waste containing methanol is inhibitory to microbial growth and may be toxic to the environment, if released without proper treatment[23] [24]. Excess methanol present in crude glycerol may contaminate the ground water. "
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    ABSTRACT: Tremendous increase in urbanization leads to the rapid depletion of fossil fuels which results in the search of alternate renewable energy. Amongst various range of alternate sources of renewable energy biodiesel is found to be potential fuel which can satisfy the energy needs. Crude glycerol production was flooded as the result of increase in biodiesel industries around the world; this crude contains various organic and inorganic impurities such as salt, ash, methanol and free fatty acids. This crude is rich in carbon and energy source, which can support microbial growth thereby producing value added bio products. Several studies have been made for the effective utilization of crude glycerol for the production of value added products. The bioconversion of crude glycerol offers safe and more viable biotechnological processes are imposed to produce a high value chemical such as DHA, ethanol, succinic acid etc.,. DHA is a value added chemical commonly used in cosmetics as an artificial browning agent and is generally produced by glycerol oxidation. In this review, a comprehensive study was carried on various microbial sources which can effectively convert glycerol for the production of DHA.
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