Modificações estruturais e operacionais de biorreatores utilizando impressão 3D: caracterização hidrodinâmica e automatização da coleta e tratamento de dados
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Data
2021-12-16
Autores
Mazziero, Vítor Teixeira
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os biorreatores podem ser modificados para atender as necessidades de cada bioprocesso específico. Tais modificações estruturais e operacionais são realizadas no âmbito comparativo, necessitando de um método de produção rápido e barato. Nesse contexto, a impressão 3D é utilizada para confecção de novas estruturas capazes de alterar a fluidodinâmica interna de biorreatores. Assim, os resultados de diferentes parâmetros fluidodinâmicos, como kLa, retenção gasosa, tempo de mistura e potência consumida auxiliam na escolha e comparação de diversas geometrias. Por isso, o tratamento de dados de forma objetiva e uniforme se fez necessário tanto para tanques agitados quanto para airlift. O foco principal para melhoria de tanques agitados está relacionado ao estudo de diversos tipos de impelidores e suas dimensões. Os valores de kLa, potência consumida e tempo de mistura se mostraram dependentes do tipo de escoamento manifestado pela interação das pás do impelidor com o fluido. Os impelidores foram modificados de forma a incluir atributos não convencionais, como a autoindução de gás. Tais impelidores indutores de gás, que foram caracterizados empregando parâmetros específicos, como a rotação crítica e vazão de gás nas pontas das pás, apresentaram-se, em diferentes configurações, como alternativas à adição e dispersão de gás no meio. De modo análogo, a impressão 3D foi aplicada à reatores airlift de circulação interna buscando melhorias no escoamento multifásico ao substituir o tubo interno padrão por tubos que exibem características singulares. Empregando uma cesta de tubo interno sólido, o airlift foi adequado para operação como leito fixo. Como as partículas sólidas do leito são um obstáculo para o escoamento, um equacionamento específico, dado a partir da retenção gasosa, foi proposto e relacionado com valores de tempos de residência médios obtidos. A modificação operacional de airlifts também foi realizada ao aplicar um controle de escoamento axial, com a alternância de riser e downcomer, por meio de um sistema modular que possibilita cultivos em semicontínuo. O sistema modular não demonstrou efeitos negativos no kLa e resultou em uma maior retenção gasosa, no entanto necessitou de alterações na forma de alimentação para alcançar tempos de mistura globais compatíveis com o tubo interno padrão, o que indica sua utilização em airlifts com grandes variações internas de volume de meio.
Bioreactors can be modified to meet the needs of each specific bioprocess. Such structural and operational modifications are carried out in the comparative scope, requiring a quick and cheap production method. In this context, 3D printing is used to build new structures capable of changing the internal fluid dynamics of bioreactors. Thus, the results of different fluid dynamic parameters, such as kLa, gas hold-up, mixing time and power requirements, help in choosing and comparing different geometries. Therefore, objective and uniform data processing was necessary for internal-loop airlift. The main focus for improving agitated tanks is related to the study of different types of impellers and their dimensions. The values of kLa, consumed power and mixing time were shown to be dependent on the type of flow manifested by the interaction of the impeller blades with the fluid. Impellers were modified to include unconventional attributes such as self-induction of gas. These gas-inducing impellers, which were characterized using specific parameters, such as critical rotation and gas flow at the tips of the blades, presented themselves, in different configurations, as alternatives to the addition and dispersion of gas to the medium. Similarly, 3D printing was used in internal circulation airlift reactors seeking improvements in multiphase flow by replacing the solid wall inner tube with tubes that have unique characteristics. Using a solid inner tube basket, the airlift was suited for operation as a packed-bed. As the solid particles of the bed are an obstacle for the flow, a specific set of equations, given from the gas hold-up, were proposed and related to the obtained mean residence time values. The operational modification of airlifts was done by applying an axial flow control, with the alternation of riser and downcomer, through a modular system that allows for semi-continuous cultivation. Such a change did not demonstrate a negative effect on kLa and resulted in a greater gas hold-up, but required changes in the form of feed to achieve global mixing times compatible with the standard inner tube, which indicates the use of the modular system in airlifts with large internal medium volume variations.
Bioreactors can be modified to meet the needs of each specific bioprocess. Such structural and operational modifications are carried out in the comparative scope, requiring a quick and cheap production method. In this context, 3D printing is used to build new structures capable of changing the internal fluid dynamics of bioreactors. Thus, the results of different fluid dynamic parameters, such as kLa, gas hold-up, mixing time and power requirements, help in choosing and comparing different geometries. Therefore, objective and uniform data processing was necessary for internal-loop airlift. The main focus for improving agitated tanks is related to the study of different types of impellers and their dimensions. The values of kLa, consumed power and mixing time were shown to be dependent on the type of flow manifested by the interaction of the impeller blades with the fluid. Impellers were modified to include unconventional attributes such as self-induction of gas. These gas-inducing impellers, which were characterized using specific parameters, such as critical rotation and gas flow at the tips of the blades, presented themselves, in different configurations, as alternatives to the addition and dispersion of gas to the medium. Similarly, 3D printing was used in internal circulation airlift reactors seeking improvements in multiphase flow by replacing the solid wall inner tube with tubes that have unique characteristics. Using a solid inner tube basket, the airlift was suited for operation as a packed-bed. As the solid particles of the bed are an obstacle for the flow, a specific set of equations, given from the gas hold-up, were proposed and related to the obtained mean residence time values. The operational modification of airlifts was done by applying an axial flow control, with the alternation of riser and downcomer, through a modular system that allows for semi-continuous cultivation. Such a change did not demonstrate a negative effect on kLa and resulted in a greater gas hold-up, but required changes in the form of feed to achieve global mixing times compatible with the standard inner tube, which indicates the use of the modular system in airlifts with large internal medium volume variations.
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Palavras-chave
Impressão 3D, Biorreatores Airlift, Biorreatores Tanque Agitado, 3D Printing, Stirred-tank Bioreactor, Airlift Bioreactor