Browsing by Author "Miranda, J. R."
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- Bioethanol production from Scenedesmus obliquus sugars: the influence of photobioreactors and culture conditions on biomass productionPublication . Miranda, J. R.; Passarinho, Paula; Gouveia, LuisaA closed-loop vertical tubular photobioreactor (PBR), specially designed to operate under conditions of scarce flat land availability and irregular solar irradiance conditions, was used to study the potential of Scenedesmus obliquus biomass/sugar production. The results obtained were compared to those from an open-raceway pond and a closed-bubble column. The influence of the type of light source and the regime (natural vs artificial and continuous vs light/dark cycles) on the growth of the microalga and the extent of the sugar accumulation was studied in both PBRs. The best type of reactor studied was a closed-loop PBR illuminated with natural light/dark cycles. In all the cases, the relationship between the nitrate depletion and the sugar accumulation was observed. The microalga Scenedesmus was cultivated for 53 days in a raceway pond (4,500 L) and accumulated a maximum sugar content of 29 % g/g. It was pre-treated for carrying out ethanol fermentation assays, and the highest ethanol concentration obtained in the hydrolysate fermented by Kluyveromyces marxianus was 11.7 g/L.
- Microalgae as a sustainable raw material for biofuels production and high added value compounds extraction by an integrated biorefinary conceptPublication . Gouveia, Luisa; Matos, Cristina T.; Oliveira, Ana Cristina; Passarinho, Paula; Miranda, J. R.; Paulo, V.; Marques, Paula; Batista, Ana Paula; Moura, Patrícia; Alves, Luís; Ortigueira, Joana; Nobre, B. P.; Palavra, António F.
- Pre-treatment optimization of Scenedesmus obliquus microalga for bioethanol productionPublication . Miranda, J. R.; Passarinho, Paula; Gouveia, LuisaThe present work deals with the optimization of cellular disruption and sugar extraction from the microalgae Scenedesmusobliquus (Sc) for bioethanol production. Among the physical and physicochemical methods tested, the best results were obtained with acid hydrolysis by H2SO4 (2 N), at 120 °C for 30 min and using dried biomass. The sugar extraction efficiency level reached was 95.6% when compared to the harsh quantitative acid hydrolysis. The influence of other parameters such as biomass loading and number of extraction cycles were also evaluated. The results obtained in the latter case showed that a unique hydrolysis step is sufficient.