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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Estudo da produção de lipídeos e carotenoides por Chlorella minutissima em fotobiorreator

Redaelli, Cristiane January 2012 (has links)
Neste trabalho é proposto o desenvolvimento de um processo para a biofixação do dióxido de carbono através do uso de microalgas. Para o cultivo desses microrganismos foram utilizados fotobiorreatores do tipo airlift. Nos cultivos foram avaliadas espécies de microalgas (Chlorella sp. e Chlorella minutissima), influência da intensidade luminosa (2.200 a 24.500 lx), concentração salina (28 a 40 g.L-1) e temperatura (25 °C a 35 °C) sobre a concentração de biomassa, velocidade específica de crescimento, produtividade de biomassa, biofixação de CO2, conteúdo lipídico e carotenoides totais. Também foi realizada a identificação dos carotenoides. A microalga escolhida para os testes em fotobiorreatores foi a C. minutissima. A intensidade luminosa que apresentou os melhores resultados foi a de 17.000 lx. A temperatura mostrou possuir influência significativa na concentração de biomassa, na velocidade específica de crescimento e na biofixação de carbono, mas a concentração salina influenciou apenas a velocidade específica de crescimento. A temperatura de 25 °C apresentou as maiores produtividade de biomassa (0,094 g.L-1.d-1) e concentração de biomassa (0,43 g.L-1), independente da concentração salina, e as maiores velocidade específica de crescimento (0,81 d-1) e biofixação de CO2 (12 gCO2.m-3.h-1), na concentração salina de 37 g.L-1. O conteúdo lipídico médio das microalgas foi de 13,2 % e os carotenoides totais apresentaram teor de 0,25 % do peso seco das microalgas em todas as condições de concentração salina e temperatura testadas. Foi possível identificar a produção dos carotenoides luteína, zeaxantina e β-caroteno. / The present study proposes the development of a process for carbon dioxide biofixation through the use of microalgae. Flat-plate airlift photobioreactors were used. Microalgaes species (Chlorella sp. and Chlorella minutissima) and the influence of light intensity (2,200 to 24,000 lx), salt concentration (28 to 40 g.L-1) and temperature (25 to 35 °C) over biomass concentration, specific growth rate, biomass productivity, CO2 biofixation rate, lipid content and total carotenoids content were evaluated. The identification of the carotenoids was performed. C. minutissima showed the best performance in shaker and was chosen for the tests in photobioreactor. The light intensity of 17,000 lx presented the best results. The temperature showed to have significant influence over biomass concentration, specific growth rate and CO2 biofixation rate, but the salt concentration only affected the specific growth rate. The temperature of 25 °C allowed the highest biomass productivity (0.094 g.L-1.d-1) and biomass concentration (0.43 g.L-1), independent of salt concentration, and the highest specific growth rate (0.81 d-1) and CO2 biofixation rate (12 gCO2.m-3.h-1) at the salt concentration of 37 g.L-1. The average lipid content of the microalgae was 13.2 % and the total carotenoids content were about 0.25 % of the cell dry weight at all temperatures and salt concentrations tested. It was possible to identify the production of the carotenoids lutein, zeaxanthin and β-carotene.
52

Estudo da produção de lipídeos e carotenoides por Chlorella minutissima em fotobiorreator

Redaelli, Cristiane January 2012 (has links)
Neste trabalho é proposto o desenvolvimento de um processo para a biofixação do dióxido de carbono através do uso de microalgas. Para o cultivo desses microrganismos foram utilizados fotobiorreatores do tipo airlift. Nos cultivos foram avaliadas espécies de microalgas (Chlorella sp. e Chlorella minutissima), influência da intensidade luminosa (2.200 a 24.500 lx), concentração salina (28 a 40 g.L-1) e temperatura (25 °C a 35 °C) sobre a concentração de biomassa, velocidade específica de crescimento, produtividade de biomassa, biofixação de CO2, conteúdo lipídico e carotenoides totais. Também foi realizada a identificação dos carotenoides. A microalga escolhida para os testes em fotobiorreatores foi a C. minutissima. A intensidade luminosa que apresentou os melhores resultados foi a de 17.000 lx. A temperatura mostrou possuir influência significativa na concentração de biomassa, na velocidade específica de crescimento e na biofixação de carbono, mas a concentração salina influenciou apenas a velocidade específica de crescimento. A temperatura de 25 °C apresentou as maiores produtividade de biomassa (0,094 g.L-1.d-1) e concentração de biomassa (0,43 g.L-1), independente da concentração salina, e as maiores velocidade específica de crescimento (0,81 d-1) e biofixação de CO2 (12 gCO2.m-3.h-1), na concentração salina de 37 g.L-1. O conteúdo lipídico médio das microalgas foi de 13,2 % e os carotenoides totais apresentaram teor de 0,25 % do peso seco das microalgas em todas as condições de concentração salina e temperatura testadas. Foi possível identificar a produção dos carotenoides luteína, zeaxantina e β-caroteno. / The present study proposes the development of a process for carbon dioxide biofixation through the use of microalgae. Flat-plate airlift photobioreactors were used. Microalgaes species (Chlorella sp. and Chlorella minutissima) and the influence of light intensity (2,200 to 24,000 lx), salt concentration (28 to 40 g.L-1) and temperature (25 to 35 °C) over biomass concentration, specific growth rate, biomass productivity, CO2 biofixation rate, lipid content and total carotenoids content were evaluated. The identification of the carotenoids was performed. C. minutissima showed the best performance in shaker and was chosen for the tests in photobioreactor. The light intensity of 17,000 lx presented the best results. The temperature showed to have significant influence over biomass concentration, specific growth rate and CO2 biofixation rate, but the salt concentration only affected the specific growth rate. The temperature of 25 °C allowed the highest biomass productivity (0.094 g.L-1.d-1) and biomass concentration (0.43 g.L-1), independent of salt concentration, and the highest specific growth rate (0.81 d-1) and CO2 biofixation rate (12 gCO2.m-3.h-1) at the salt concentration of 37 g.L-1. The average lipid content of the microalgae was 13.2 % and the total carotenoids content were about 0.25 % of the cell dry weight at all temperatures and salt concentrations tested. It was possible to identify the production of the carotenoids lutein, zeaxanthin and β-carotene.
53

En teoretisk grund för Sveriges nästa militära transportflygplan

Maspers Linde, Philip January 2020 (has links)
Sverige har Europas äldsta C-130 Herculesflotta, nationellt benämnt Transportflygplan 84, som ska bytas ut innan 2030 på grund av ökande underhållskostnader. Det har ännu inte identifierats eller beslutats om en lämplig ersättare till TP 84. Detta arbete studerar the fiktiva scenariot av införskaffning och implementering av ett större transportflygplan än TP 84 för att användas i taktiska operationer. Arbetet svarar på frågan Hur påverkas Försvarsmakten av införskaffandet av ett stort transportflygplan med hänsyn till effekt, lämplighet och ekonomisk överkomlighet? Detta ämnas besvaras genom att applicera teorin om militär nytta på flygplanet C-130J Super Hercules, som är i motsvarande storlek som TP 84 samt C-17 Globemaster III som är större och vanligtvis används till strategiska operationer. Syftet med arbetet uppnås genom insamlad empiri från dokumentstudier från både officiella dokument, tidigare studier och elektroniska dokument som kompletteras av en intervju med en före detta överste vid svenska transport- och specialflygsdivisionen. Arbetets slutsats är att en implementering av ett större transportflygplan påverkar Sveriges transportflygsförmåga negativt. Ett flygplan i motsvarande storlek som TP 84 är att föredra för taktiska operationer. Arbetet bidrar även med två förbättringspunkter till teorin om militär nytta där dimensionen Ekonomisk Överkomlighet föreslås få större inverkan på den slutgiltiga bedömningen samt att lägga till ytterligare en indikator under dimensionen Militär Lämplighet som bör beröra området politik. / Sweden currently operates the oldest C-130 Hercules fleet in Europe which is to be replaced before 2030 due to rising maintenance costs. A suitable military cargo aircraft has not yet been identified nor decided upon. This report studies the fictional case of acquiring and implementing a larger aircraft than the C-130H Hercules for use in tactical operations. The report answers the question How would an implementation of a large military cargo aircraft affect the Swedish Armed Forces regarding military effect, military suitability and economic affordability? This question aims to examine the implementation by applying the theory of Military Utility on the C-130J Super Hercules which has a size comparable to C-130H Hercules and the C-17 Globemaster III which is larger and commonly used for strategic airlift. The purpose of this study is achieved by gathering empirical data by using documentary studies from both official government documents, previous studies and electronic documents as well as from an interview with a former Air Force Colonel responsible for the development of the Swedish airlift squadron. The author concludes that the implementation of a larger aircraft negatively impacts the airlift capabilities. An aircraft in the same size as C-130H Hercules is preferred for tactical operations. This report also contributes with two key points to improve the theory of military utility by giving the dimension Economic Affordability a larger impact in the final judgement as well as implementing an additional indicator to the dimension Military Suitability, named political.
54

Mathematical modeling of cellulase production in an airlift bioreactor / Modélisation mathématique de la production de cellulase dans un réacteur airlift

Bannari, Rachid January 2009 (has links)
Fossil fuel is an important energy source, but is unavoidabiy running out. Since the cellulosic material is the most abundant source of organic matter, the ethanol, which is produced from cellulosic waste materials, is gaining more and more attention. These materials are cheap, renewable and their availability makes them superior compared to other raw materials. The cellulose must be hydrolyzed to glucose before it can be fermented to ethanol. The enzymatic hydrolysis of cellulose using cellulase enzymes is the most widely used method. The production cost of cellulase enzymes is the major cost in ethanol manufacture. To optimize the cost of ethanol production, enzyme stability needs to be improved through maintaining the activity of the enzymes and by optimizing the production of the cellulase. The aim of researchers, engineers and industrials is to get more biomass for the same cost. The filamentous fungus Trichoderma reesei has a long history in the production of the cellulase enzymes. This production can be influenced strongly by varying the growth media and culture conditions (pH, temperature, DO, agitation,... ). At present, it is my opinion that no modelling study has included both the hydrodynamic and kinetic aspects to investigate the effect of shear and mass transfer on the morphology of microorganisms that influence the rheology of the broth and production of cellulase. This thesis presents the development of a mathematical model for cellulase production and the growth of biomass in an airlift bioreactor. The kinetic model is coupled with the methodology of two-phase flow using mathematical models based on the bubble break-up and coalescence to predict mass transfer rate, which is one of the critical factor in the fermentation. A comparison between the results obtained by the developed model and the experimental data is given and discussed. The design proposed for the airlift geometry by Ahamed and Vermette enables us to get a high mass transfer and production rate. The results are very promising with respect to the potential of such a model for industrial use as a prediction tool, and even for design.
55

Impact de l'agitation et de l'aération sur la réponse physiologique de Streptomyces pristinaespiralis DSMZ 40338 lors de sa culture en bioréacteurs mécaniquement agité et gazosiphon / Influence of agitation and aeration on the physiological behavior of Streptomyces pristinaespiralis DSMZ 40338 during cultures in stirred tank and airlift bioreactors

Haj-Husein, Laial 15 October 2013 (has links)
Des travaux préliminaires réalisés en fiole d'Erlenmeyer ont montré que l'environnement hydrodynamique, caractérisé par la puissance dissipée volumique (P/V) et le coefficient de transfert en oxygène (kLa), jouait un rôle important lors du procédé de production de pristinamycines par Streptomyces pristinaespiralis (Mehmood, 2011). L'objectif de ce travail est donc d'étudier l'influence de ces deux phénomènes dans des bioréacteurs mécaniquement agités (STR), largement utilisés à l'échelle industrielle, et de type gazosiphon. Dans un premier temps, une description de l'environnement hydrodynamique global a été réalisée en STR. En ce qui concerne le bioréacteur gazosiphon, celui-ci a été conçu et dimensionné spécifiquement pour ce travail. Une caractérisation des écoulements dans ce bioréacteur a ensuite été réalisée par simulation numérique des écoulements. En appliquant les mêmes conditions hydrodynamiques que celles étudiées lors de culture en fioles d'Erlenmeyer, les performances en terme de croissance et de production de pristinamycines ont toujours été moindres en STR et en gazosiphon qu'en fiole. Ceci démontre que P / V, kLa mais également la dissipation maximum, ne constituent pas les bons paramètres d'extrapolation. Par contre, les performances mesurées semblent être reliée aux variations de formes morphologiques observées (présence et taille des pelotes) et à la physiologie des cellules au sein de ces structures. De façon surprenante, au cours de ce travail, le déclenchement de la production de pristinamycines a quasiment toujours été obtenu lors de la phase de croissance de S. pristinaespiralis. Nos travaux n'ont pas permis de mettre en évidence la raison de ce phénomène. Celui-ci est certainement la conséquence de plusieurs paramètres qui restent encore à préciser / Previous results performed in Erlenmeyer flasks have shown that the hydrodynamics, characterized by power dissipation per unit of volume (P/V) and volumetric oxygen mass transfer coefficient (kLa), impacted the production of pristinamycins by Streptomyces pristinaespiralis (Mehmood, 2011). The aim of this work is then to study the influence of these two parameters in a stirred tank bioreactor (STR), widely used in industry, and in an airlift bioreactor. This last bioreactor has been designed specifically for this work. In a first part, the hydrodynamic environment was described in STR and the fluid flows were simulated by computational fluid dynamics (CFD). Using the same hydrodynamic conditions in STR and in airlift bioreactor than in flasks, the process performance (bacterial growth and pristinamycin production) were always lower in STR and airlift bioreactor. This demonstrates that P / V, kLa and also maximum dissipation were not pertinent scale-up criteria for the pristinamycin production from flask to STR or airlift bioreactor. On the contrary, the determined performances seemed to be related to the changes in bacterial morphology (presence and size of pellets) and to the physiology of the cells inside these structures. Surprisingly, during this work, the initiation of the pristinamycin production occurred almost always during the growth phase of S. pristinaespiralis. This phenomenon was probably due to the conjunction of several parameters which remain to identify
56

Basic Expeditionary Airfield Resource (BEAR) Requirements Analysis Tool (BRAT)

Hunt, Andrew W. January 2008 (has links)
Thesis (Master of Military Studies)-Marine Corps Command and Staff College, 2008. / Title from title page of PDF document (viewed on: Jan 5, 2010). Includes bibliographical references.
57

Simulation en présence d'incertitude d'un gazosiphon de grande échelle. Application à l'optimisation d'un nouveau système géothermique urbain / Simulation of a large-scale airlift pump taking into account uncertainties. Application to the optimization of a new urban geothermal system

Monmarson, Bastien 22 October 2015 (has links)
Cette thèse s’inscrit dans le cadre du projet ANR « Uncertain flow optimization » (UFO) consacré au développement et à l’application de méthodes efficaces de quantification d’incertitudes pour l’analyse et l’optimisation d’écoulements. Dans ce contexte, ces méthodes sont appliquées à des gazosiphons de grande échelle utilisés comme pompe. Plus particulièrement, on s’intéresse à de tels gazosiphons choisis pour constituer l’organe central d’un système géothermique innovant,  compatible avec un environnement urbain. On souhaite en quantifier le potentiel énergétique par voie numérique avec la recherche d’un compromis entre justesse des résultats et efficacité optimale. La simulation de l’écoulement diphasique produit dans le gazosiphon est fondée sur un modèle quasi-1D à flux de dérive et s’appuie sur une démarche de résolution implicite. Les résultats sont validés sur les études expérimentales les plus pertinents de la littérature, dont aucune toutefois n’atteint les longueurs requises de l'ordre du kilomètre. Le code de simulation du gazosiphon fait ensuite l’objet d’une démarche de prise en compte d’incertitudes physiques et de modélisation, précédée par une analyse de deux méthodes de quantification d’incertitude : une méthode non-intrusive de type chaos polynomial, et une méthode plus récente dite semi-intrusive qui fut développée en amont du projet UFO. Cet outil est intégré dans une modélisation simplifiée du système géothermique urbain dans son ensemble impliquant les composants en surface, notamment le compresseur d'air. Il en résulte une optimisation énergétique robuste préliminaire de deux variantes du système géothermique urbain proposé, respectivement de récupération de chaleur et de production d’électricité. / This PhD thesis is part of the ANR project « Uncertain Flow Optimization » (UFO). The project is devoted to the development and application of efficient uncertainty quantification methods for flow analysis and optimization. In this framework, these methods are applied to the study of a large-scale airlift pump. The airlift pump is selected to be part of an innovative geothermal system, which can be exploited within an urban environment. We wish to quantify and optimize the energy potential of this new system with numerical tools. They provide both good accuracy and efficiency properties. The airlift two-phase flow simulation is based on a quasi one-dimensional drift flux model, which is implicitly solved. The solver is validated by comparison with relevant experimental airlift studies from the literature. However, these studies remain below the kilometric-targeted pipe length. Thanks to the analysis of two uncertainty quantification methods, a non-intrusive approach relying on polynomial chaos expansion and a new semi-intrusive method developed ahead of the UFO project, we perform airlift pump simulations taking into account physical and modelling uncertainties. This numerical tool is inserted into a simplified model of the complete urban geothermal system that involves surface devices, such as an air compressor. Finally, a robust preliminary optimization process is performed for two versions of the proposed geothermal urban system. They are designed respectively for heat recovery and electricity production.
58

Produção de carotenoides e lipídeos pela microalga Dunaliella tertiolecta utilizando CO2 de fermentação de cerveja

Chagas, Arthur Lygeros das January 2014 (has links)
O presente trabalho avaliou o crescimento da microalga Dunaliella tertiolecta pela biofixação do CO2 liberado pela produção de cerveja, reciclando um dos gases responsáveis pelo efeito estufa, reduzindo custo da matéria-prima CO2 e agregando valor ao produzir lipídeos e carotenoides naturais. Para isso a microalga foi cultivada em sistemas integrados entre fotobiorreatores e fermentadores. A diferença nos cultivos foi o tipo e a quantidade de CO2 produzida pelas fermentações. Inicialmente se fez fermentações com meio YPD (Yeast Peptone Dextrose) em fermentadores de 2 L acoplados a cada 24 h aos fotobiorreatores em 4 condições distintas, sendo o último fermentador colocado sempre em 144 h de cultivo de microalgas: 30 g L-1 de dextrose a partir de 72 h de cultivo de microalgas, 60 g L-1 de dextrose a partir de 72 h de cultivo de microalgas, 30 g L-1 de dextrose a partir de 24 h de cultivo de microalgas e variando a concentração de (10 à 60) g L-1 de dextrose a partir de 24 h de cultivo de microalgas (YPD (10-60)/24). Os maiores valores para biomassa, carotenoides, produtividades e lipídeos foram obtidos na condição YPD (10-60)/24. Para reproduzir a essa condição utilizando mosto de cerveja, foi calculada a conversão de substrato em produto para, então, acoplar diariamente volumes diferentes de mosto de cerveja em cultivos de microalgas. Os valores obtidos para os cultivos com CO2 desprendidos por estas fermentações foram 1,10 ± 0,05 g L-1 de biomassa, 0,18 ± 0,01 g L-1 d-1 de produtividade de biomassa, 0,58 ± 0,06 d-1 foi a velocidade específica de crescimento, 4,74 ± 0,59 mg g-1 de carotenoides por biomassa, 0,86 ± 0,06 mg L-1 d-1 de produtividade de carotenoides e 13,5 ± 0,4 % (em massa) de lipídeos. Estes valores foram praticamente o dobro dos valores obtidos para o cultivo com CO2 do ar atmosférico, demonstrando que a integração entre fermentadores e fotobiorreatores é uma boa alternativa para indústria alimentícia. Todos cultivos com D. tertiolecta apresentaram o mesmo perfil de carotenoides representado por 46,7 ± 2,0 % de luteína, 22,5 ± 1,6 % de β-caroteno, 9,50 ± 0,66 % de zeaxantina, 1,10 ± 0,16 % de α-caroteno e 20,2 ± 3,0 % para outros. / This study evaluated the growth of microalgae Dunaliella tertiolecta for CO2 biofixation released by brewing, recycling one of the greenhouse gases, reducing cost of raw material CO2 and adding value to produce lipids and natural carotenoids. For this, microalgae were cultivated in integrated systems between photobioreactors and fermenters. The difference in the cultures was the culture medium and the amount of CO2 produced. Initially, fermentation with medium YPD (Yeast Peptone Dextrose) in 2 L fermenters were coupled every 24 h to photobioreactors in 4 different conditions: 30 g L-1 of dextrose from 72 h culture of microalgae; 60 g L-1 of dextrose from 72 h culture of microalgae; 30 g L-1 of dextrose from 24 h culture of microalgae; and ranging dextrose concentration of (10 to 60) g L-1 from 24 h culture of microalgae (YPD (10-60)/24). The highest values for biomass, carotenoids, productivities and lipids were obtained in the condition YPD (10-60)/24. To reproduce this condition using beer wort, the substrate to product yield was determined and different volumes of beer wort where daily coupled to microalgae cultivations. The values obtained for cultures with CO2 released from these fermentations were 1.10 ± 0.05 g L-1 of biomass, 0.18 ± 0.01 g L-1 d-1 of biomass productivity, 0.58 ± 0.06 d-1 for the specific growth rate, 4.74 ± 0,59 mg g-1 of carotenoids per biomass, 0.86 ± 0.06 mg L-1 d-1 of carotenoids productivity and 13.5 ± 0.4 % (mass fraction) of lipids. These values were almost twice the values observed in the cultivation with CO2 of atmospheric air, showing that the integration between fermenters and photobioreactors is a good alternative to increase microalgae growth. All cultures with D. tertiolecta showed the same profile of carotenoids represented by 46.7 ± 2.0 % of lutein, 22.5 ± 1.6 % of β-carotene, 9.50 ± 0.66 % of zeaxanthin, 1.10 ± 0.16 % of α-carotene and 20.2 ± 3.0 % for others.
59

Reator airlift operado em sobrepressão: construção, caracterização da transferência de oxigênio e aplicação em cultivos de Escherichia coli recombinante

Campani Junior, Gilson 15 August 2014 (has links)
Made available in DSpace on 2016-06-02T19:56:54Z (GMT). No. of bitstreams: 1 5933.pdf: 2457795 bytes, checksum: b5b6653a532bc7e6c4a9ec2685b55277 (MD5) Previous issue date: 2014-08-15 / Universidade Federal de Minas Gerais / Owing to the broad biochemical, physiological and genetic characterization and the ease of manipulation and cultivation, several proteins with therapeutic and industrial applications are produced by genetically modified Escherichia coli. There is abundant information in the literature about strategies to increase biomass and recombinant protein production by cultivation of E. coli employing stirred and aerated tank bioreactor (conventional type). In contrast, although quite employed in cultivation of filamentous microorganisms, there are just a few studies involving cultivation of E. coli in airlift bioreactor. This reactor offers advantages over conventional one, such as simplicity of construction, reduced risk of contamination and efficient gas-liquid dispersion with low power consumption. However, the lower O2 transfer in airlift bioreactor (bench scale), compared to that achieved in conventional one, justifies the manipulation of temperature, pressure and flow rates of air and O2 in the dissolved oxygen concentration (DOC) control, avoiding decreases in biomass and recombinant protein productivities. In this context, this study aimed to: (i) determine the influence of internal pressure on the gas holdup (ɛ), volumetric O2 transfer coefficient (kLa) and volumetric O2 transfer rate (continue...). / Devido à ampla caracterização bioquímica, fisiológica e genética e à facilidade de manipulação e de cultivo, diversas proteínas com aplicação industrial e terapêutica são produzidas por Escherichia coli geneticamente modificada. Há informações abundantes na literatura sobre estratégias para aumentar a produção de biomassa e de proteínas recombinantes por meio de cultivos de E. coli empregando biorreator tipo tanque agitado e aerado (convencional). Por outro lado, apesar de bastante empregado em cultivos de microrganismos filamentosos, poucos trabalhos envolvendo cultivo de E. coli em reator pneumático tipo airlift são encontrados. Este biorreator apresenta vantagens frente ao convencional, como simplicidade de construção, menor risco de contaminação e eficiente dispersão gás-líquido com baixo consumo de energia. Entretanto, a menor capacidade de transferência de O2 no biorreator airlift em escala de bancada, em relação à alcançada em reator convencional, justifica a manipulação de variáveis como temperatura, pressão e vazões de ar e O2 no controle adequado da concentração de O2 dissolvido (COD), evitando quedas de produtividade de biomassa e de proteína recombinante. Nesse contexto, este trabalho objetivou: (i) determinar a influência da pressão interna sobre a retenção gasosa (ɛ), o coeficiente volumétrico de transferência de O2 (kLa) e a velocidade volumétrica de transferência de O2 (continua...).
60

Produção de carotenoides e lipídeos pela microalga Dunaliella tertiolecta utilizando CO2 de fermentação de cerveja

Chagas, Arthur Lygeros das January 2014 (has links)
O presente trabalho avaliou o crescimento da microalga Dunaliella tertiolecta pela biofixação do CO2 liberado pela produção de cerveja, reciclando um dos gases responsáveis pelo efeito estufa, reduzindo custo da matéria-prima CO2 e agregando valor ao produzir lipídeos e carotenoides naturais. Para isso a microalga foi cultivada em sistemas integrados entre fotobiorreatores e fermentadores. A diferença nos cultivos foi o tipo e a quantidade de CO2 produzida pelas fermentações. Inicialmente se fez fermentações com meio YPD (Yeast Peptone Dextrose) em fermentadores de 2 L acoplados a cada 24 h aos fotobiorreatores em 4 condições distintas, sendo o último fermentador colocado sempre em 144 h de cultivo de microalgas: 30 g L-1 de dextrose a partir de 72 h de cultivo de microalgas, 60 g L-1 de dextrose a partir de 72 h de cultivo de microalgas, 30 g L-1 de dextrose a partir de 24 h de cultivo de microalgas e variando a concentração de (10 à 60) g L-1 de dextrose a partir de 24 h de cultivo de microalgas (YPD (10-60)/24). Os maiores valores para biomassa, carotenoides, produtividades e lipídeos foram obtidos na condição YPD (10-60)/24. Para reproduzir a essa condição utilizando mosto de cerveja, foi calculada a conversão de substrato em produto para, então, acoplar diariamente volumes diferentes de mosto de cerveja em cultivos de microalgas. Os valores obtidos para os cultivos com CO2 desprendidos por estas fermentações foram 1,10 ± 0,05 g L-1 de biomassa, 0,18 ± 0,01 g L-1 d-1 de produtividade de biomassa, 0,58 ± 0,06 d-1 foi a velocidade específica de crescimento, 4,74 ± 0,59 mg g-1 de carotenoides por biomassa, 0,86 ± 0,06 mg L-1 d-1 de produtividade de carotenoides e 13,5 ± 0,4 % (em massa) de lipídeos. Estes valores foram praticamente o dobro dos valores obtidos para o cultivo com CO2 do ar atmosférico, demonstrando que a integração entre fermentadores e fotobiorreatores é uma boa alternativa para indústria alimentícia. Todos cultivos com D. tertiolecta apresentaram o mesmo perfil de carotenoides representado por 46,7 ± 2,0 % de luteína, 22,5 ± 1,6 % de β-caroteno, 9,50 ± 0,66 % de zeaxantina, 1,10 ± 0,16 % de α-caroteno e 20,2 ± 3,0 % para outros. / This study evaluated the growth of microalgae Dunaliella tertiolecta for CO2 biofixation released by brewing, recycling one of the greenhouse gases, reducing cost of raw material CO2 and adding value to produce lipids and natural carotenoids. For this, microalgae were cultivated in integrated systems between photobioreactors and fermenters. The difference in the cultures was the culture medium and the amount of CO2 produced. Initially, fermentation with medium YPD (Yeast Peptone Dextrose) in 2 L fermenters were coupled every 24 h to photobioreactors in 4 different conditions: 30 g L-1 of dextrose from 72 h culture of microalgae; 60 g L-1 of dextrose from 72 h culture of microalgae; 30 g L-1 of dextrose from 24 h culture of microalgae; and ranging dextrose concentration of (10 to 60) g L-1 from 24 h culture of microalgae (YPD (10-60)/24). The highest values for biomass, carotenoids, productivities and lipids were obtained in the condition YPD (10-60)/24. To reproduce this condition using beer wort, the substrate to product yield was determined and different volumes of beer wort where daily coupled to microalgae cultivations. The values obtained for cultures with CO2 released from these fermentations were 1.10 ± 0.05 g L-1 of biomass, 0.18 ± 0.01 g L-1 d-1 of biomass productivity, 0.58 ± 0.06 d-1 for the specific growth rate, 4.74 ± 0,59 mg g-1 of carotenoids per biomass, 0.86 ± 0.06 mg L-1 d-1 of carotenoids productivity and 13.5 ± 0.4 % (mass fraction) of lipids. These values were almost twice the values observed in the cultivation with CO2 of atmospheric air, showing that the integration between fermenters and photobioreactors is a good alternative to increase microalgae growth. All cultures with D. tertiolecta showed the same profile of carotenoids represented by 46.7 ± 2.0 % of lutein, 22.5 ± 1.6 % of β-carotene, 9.50 ± 0.66 % of zeaxanthin, 1.10 ± 0.16 % of α-carotene and 20.2 ± 3.0 % for others.

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