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Abstract(s)
O aumento da população mundial tem levado ao aumento do consumo de recursos, incluindo os energéticos e alimentares. Esta pressão torna urgente explorar e implementar alternativas assentes numa economia de base biológica, mais amiga do ambiente e sustentáveis. As microalgas, que podem ser usadas para alimentação humana e animal e ainda como fontes de biocombustíveis, constituem uma matéria-prima alternativa para as economias de base biológica. Apesar destes microrganismos apresentarem muitas vantagens como “fábrica biológica”, persiste a necessidade de melhorar e otimizar os processos de produção de biomassa, recolha de biomassa e extração de componentes de elevado valor acrescentado.
Nesta dissertação, foram realizados estudos nestas diferentes vertentes. Em relação à produção da biomassa (Chlorella vulgaris), utilizaram-se- reatores air-lift cilíndricos, flat-plate em modo descontínuo e em modo contínuo, sob diferentes condições de operação, concluindo-se que os reatores em modo contínuo obtiveram um melhor crescimento específico da biomassa (0,2 dia-1), quando comparados com os reatores em descontínuo (0,084 dia-1).
No que respeita à recolha da biomassa produzida, explorou-se o potencial do amido catiónico, tendo-se comparado o seu desempenho com um floculante sintético, o polyDADMAC. Os ensaios mostraram que o amido catiónico pode ser uma boa alternativa ao uso de floculantes sintéticos. Na extração dos pigmentos foi usado um método referido na literatura, e fez-se a respetiva quantificação e caraterização com recurso à cromatografia liquida acoplada à espectrometria de massa (LC-MS). Os melhores resultados foram obtidos a partir do reator Flat-plate em modo de operação contínuo, tendo-se obtido 3,8 e 1,57 mg carotenoides/g (matéria seca) de luteína e ß-caroteno, respetivamente.
Os resultados desta dissertação representam uma contribuição para a otimização da produção de microalgas e extração de produtos de valor acrescentado, reduzindo os custos de operação no futuro.
The increase in world population has led to increased consumption of resources, including energy and food. This pressure makes it imperative to explore and implement alternatives based on a bio-based, environmentally friendly and sustainable economy. Microalgae, which can be used for food and feed as well as biofuel sources, are an alternative raw material for bio-based economies. Although these microorganisms have many advantages as a "biological factory", there is still a need to improve and optimize biomass production processes, biomass collection and extraction of components with high added value. In this dissertation, studies were carried out in these different aspects. Regarding to biomass production (Chlorella vulgaris), cylindrical air-lift reactors in discontinuous-mode and flat-plate reactors in both continuous and discontinuous mode were used under different operation conditions, and it was concluded that continuous-mode reactors obtained a better specific growth of biomass (0.2 day-1) when compared to discontinuous-mode reactors (0.084 day-1). With regard to the recovery of the produced biomass, the potential of the cationic starch was explored, comparing its performance with a synthetic flocculant, polyDADMAC. The tests showed that cationic starch might be a good alternative to the use of synthetic flocculants. In the extraction of the pigments, a method referred to in the literature was used, and the respective quantification and characterization was done using liquid chromatography coupled with mass spectrometry (LC-MS). The best results were obtained with the Flat-plate reactor in continuous-mode of operation, obtaining 3.8 and 1.57 mg carotenoids / g (dry matter) of lutein and ß-carotene, respectively. The results of this dissertation represent a contribution to optimize the production of microalgae and extraction of value-added products, reducing the operating costs in the future.
The increase in world population has led to increased consumption of resources, including energy and food. This pressure makes it imperative to explore and implement alternatives based on a bio-based, environmentally friendly and sustainable economy. Microalgae, which can be used for food and feed as well as biofuel sources, are an alternative raw material for bio-based economies. Although these microorganisms have many advantages as a "biological factory", there is still a need to improve and optimize biomass production processes, biomass collection and extraction of components with high added value. In this dissertation, studies were carried out in these different aspects. Regarding to biomass production (Chlorella vulgaris), cylindrical air-lift reactors in discontinuous-mode and flat-plate reactors in both continuous and discontinuous mode were used under different operation conditions, and it was concluded that continuous-mode reactors obtained a better specific growth of biomass (0.2 day-1) when compared to discontinuous-mode reactors (0.084 day-1). With regard to the recovery of the produced biomass, the potential of the cationic starch was explored, comparing its performance with a synthetic flocculant, polyDADMAC. The tests showed that cationic starch might be a good alternative to the use of synthetic flocculants. In the extraction of the pigments, a method referred to in the literature was used, and the respective quantification and characterization was done using liquid chromatography coupled with mass spectrometry (LC-MS). The best results were obtained with the Flat-plate reactor in continuous-mode of operation, obtaining 3.8 and 1.57 mg carotenoids / g (dry matter) of lutein and ß-carotene, respectively. The results of this dissertation represent a contribution to optimize the production of microalgae and extraction of value-added products, reducing the operating costs in the future.
Description
Keywords
Amido Catiónico Chlorella Vulgaris Fotobiorreatores Air-Lift Fotobiorreatores Flat-Plate Luteína ß-Caroteno.