Publicação
Produção de biohidrogénio por fermentação aneróbia, a partir de resíduos fermentescíveis
| Resumo: | As the world's energy need has been increasing exponentially, it is clear that reducing the dependence on fossil fuels is essential, given the decline of its reserves and the pollution generated by its use for energy. In this context, hydrogen is considered as a "clean" alternative, and a possible viable energy carrier for the future. The biological production of hydrogen (biohydrogen) represents only about 1% of total production. However, once this process has a favorable energy balance compared to conventional procesess, it has been subjected to development during past years, aiming at the improving and increasing yields. In this study, a microbiological anaerobic production of hydrogen, using different carbon sources, with simultaneous recovery of industrial waste, was conducted. Thus, in the first phase, based on previous studies with glycerol contained in wastes from the production of biodiesel as substrate, the composition of fermentation medium, in terms of concentration of the most economic valuable compounds (tryptone and yeast extract), was optimized according to the methodology of the Central Composite Design (DCC). In a second phase, the production of H2, under the same operating conditions, using glucose and xylose in synthetic medium and contained in paper sludge hydrolysates, as carbon source, was evaluated. Finally, the effect of the volume of headspace and the volume of the liquid phase on the process, was carried out. The results showed that the increase of tryptone and yeast extract concentration resulted in the increase in the volume of hydrogen produced and simultaneously in the decrease in the volume ratio H2/CO2, suggesting that in terms of economic analysis, there should be a commitment between the two factors Moreover, it was observed that the performance of the bacteria was not significantly affected by the presence of compounds other than glucose and xylose in paper hydrolysates, which is an advantage, considering the application of these process to a real system. Finally, it was found that the increase in the headspace with the increase of the ratio VTotal.reactor / Vliquid phase, was more efficient in terms of increasing the volumetric efficiency of the process (from 2.5 to 4.5 mL H2/mL fermentation medium) than the increase in the volume of the liquid phase at constant ratio, leading to similar values of volumetric efficiency (between 2 and 2.5 mL H2/mL fermentation medium). |
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| Autores principais: | Correia, Ricardo Miguel de Sousa Carapeto |
| Assunto: | Hidrogénio Enterobacter aerogenes Resíduos Glicerol Glucose e xilose Teses de mestrado - 2009 |
| Ano: | 2009 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | português |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | As the world's energy need has been increasing exponentially, it is clear that reducing the dependence on fossil fuels is essential, given the decline of its reserves and the pollution generated by its use for energy. In this context, hydrogen is considered as a "clean" alternative, and a possible viable energy carrier for the future. The biological production of hydrogen (biohydrogen) represents only about 1% of total production. However, once this process has a favorable energy balance compared to conventional procesess, it has been subjected to development during past years, aiming at the improving and increasing yields. In this study, a microbiological anaerobic production of hydrogen, using different carbon sources, with simultaneous recovery of industrial waste, was conducted. Thus, in the first phase, based on previous studies with glycerol contained in wastes from the production of biodiesel as substrate, the composition of fermentation medium, in terms of concentration of the most economic valuable compounds (tryptone and yeast extract), was optimized according to the methodology of the Central Composite Design (DCC). In a second phase, the production of H2, under the same operating conditions, using glucose and xylose in synthetic medium and contained in paper sludge hydrolysates, as carbon source, was evaluated. Finally, the effect of the volume of headspace and the volume of the liquid phase on the process, was carried out. The results showed that the increase of tryptone and yeast extract concentration resulted in the increase in the volume of hydrogen produced and simultaneously in the decrease in the volume ratio H2/CO2, suggesting that in terms of economic analysis, there should be a commitment between the two factors Moreover, it was observed that the performance of the bacteria was not significantly affected by the presence of compounds other than glucose and xylose in paper hydrolysates, which is an advantage, considering the application of these process to a real system. Finally, it was found that the increase in the headspace with the increase of the ratio VTotal.reactor / Vliquid phase, was more efficient in terms of increasing the volumetric efficiency of the process (from 2.5 to 4.5 mL H2/mL fermentation medium) than the increase in the volume of the liquid phase at constant ratio, leading to similar values of volumetric efficiency (between 2 and 2.5 mL H2/mL fermentation medium). |
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