Balanço material de uma planta industrial produtora de enzimas celulolíticas por cultivo em estado sólido
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Data
2021-03-04
Autores
Gouveia, Antéia Olhiana
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Universidade Estadual Paulista (Unesp)
Resumo
Enzimas celulolíticas são fundamentais para o processo de produção de etanol de segunda geração (E2G). Todavia, o alto custo comercial destas enzimas requer novas vias de obtenção para tornar o E2G mais competitivo e, nesse sentido, o cultivo em estado sólido (CES) tem se mostrado uma opção promissora. Esse trabalho teve por objetivo estruturar e dimensionar em termos de balanço material um processo de produção industrial de enzimas celulolíticas por CES, cuja planta produtora estaria acoplada a uma planta convencional de produção de etanol. O processo de produção proposto é contínuo, mas comporta algumas etapas descontínuas, de modo que o fluxograma de processo e a cronologia das etapas buscou solucionar esta dificuldade. O microrganismo empregado foi o fungo termofílico Myceliophtora thermophila I-1D3b, cultivado em uma mistura de bagaço de cana e farelo de trigo (biomassa), na proporção 7:3 (p/p), a 45 °C por 96h. A base de cálculo deste projeto baseou-se em uma indústria sucroenergética de médio porte, com capacidade de processamento de 1,6 milhões de toneladas de cana por safra, e uma planta produtora de enzimas que processaria 12.000 toneladas de uma mistura de bagaço de cana e farelo de trigo (biomassa) por safra. Os principais gargalos operacionais foram identificados e soluções apontadas e, a partir dos cálculos de fluxo de massa, a quantidade e capacidade nominal dos equipamentos propostos foram estabelecidas, detalhando-se estes equipamentos sempre que possível. Definiu-se a forma de esterilização dos substratos, através da operação contínua em uma rosca sem fim com a injeção de vapor saturado, e o resfriamento, ocorrendo em um tambor rotativo pela admissão de ar seco resfriado. Estabeleceu-se um processo de CES para a produção de inóculo em biorreatores de bandeja. A mistura e inoculação da biomassa foram configuradas para ocorrer continuamente em tambor rotativo. O CES para a produção das enzimas foi proposto em biorreatores de leito empacotado, instalando-se uma rosca sem fim em seu interior para auxiliar no carregamento, descarregamento e estruturação da biomassa durante o cultivo, além de prover ar ao sistema. Por fim, a extração líquida das enzimas deu-se em tanque agitado, com a separação da biomassa sólida residual ocorrendo por filtração a vácuo em tambor rotativo. Projetada com um total de 20 biorreatores de leito empacotado de 150 m3 cada, a planta produtora de enzimas celulolíticas apresentou uma atividade enzimática total de 8,45x1010 FPU por safra e um total de 4,59x105 FPU por metro cúbico de extrato enzimático líquido obtido por safra, cuja aplicação prevista atende cerca de 10 % da demanda de bagaço de cana disponível para hidrólise por safra.
Cellulases are fundamental for the process of production of second-generation ethanol (2GE). Nevertheless, the high cost of commercial preparations asks for new routes of production of enzymes in order to make 2EG more competitive, and solid-state cultivation (SSC) has been shown to be a promising alternative for such purpose. This work aimed to propose a structure and the material flow of an industrial process of production of cellulases by SSC, which would be coupled with a conventional ethanol production plant and to a 2EG process. The proposed process is continuous, even though some batch steps are forecasted and the process integration is troublesome. The microbe was the thermophilic fungus Myceliophthora thermophila I-1D3b, which is cultivated in a mixture of sugarcane bagasse and wheat bran at a proportion 7:3 (w/w), 45 °C and 96h. This process was based in a medium-size sucroenergetic industry, which process 1.6 million tons of cane per crop. The main bottlenecks were identified and possible solutions proposed and, from the mass balances, the quantity and nominal capacity of the equipments were determined, and details of these equipments were presented when possible. Continual sterilization was used for the biomass, using direct flow of saturated steam in an endless thread apparatus, followed by refrigeration in a rotating drum. The inoculum was proposed to be produced by SSC in tray bioreactors. The mixture sugarcane bagasse-wheat bran would be mixed and inoculated in a rotating drum. The production of enzymes would take place by SSC in packed-bed bioreactors and an endless thread would be installed in it for the charge and discharge of biomass and to provide physical structure and air to the cultivation medium. Water would be added to the cultivated biomass to extract the enzymes in an agitated vessel, and the enzymatic extract would be separated from the biomass in a vacuum rotating drum. The enzymes would be produced in 20 bioreactors of 150m3 each, and the total enzyme activity produced would be of 8.45 10 10 FPU per crop and 4.59 105 FPU/m3 of enzymatic extract, whose expected application provides 10 % of the demand for sugarcane bagasse available for hydrolysis per crop.
Cellulases are fundamental for the process of production of second-generation ethanol (2GE). Nevertheless, the high cost of commercial preparations asks for new routes of production of enzymes in order to make 2EG more competitive, and solid-state cultivation (SSC) has been shown to be a promising alternative for such purpose. This work aimed to propose a structure and the material flow of an industrial process of production of cellulases by SSC, which would be coupled with a conventional ethanol production plant and to a 2EG process. The proposed process is continuous, even though some batch steps are forecasted and the process integration is troublesome. The microbe was the thermophilic fungus Myceliophthora thermophila I-1D3b, which is cultivated in a mixture of sugarcane bagasse and wheat bran at a proportion 7:3 (w/w), 45 °C and 96h. This process was based in a medium-size sucroenergetic industry, which process 1.6 million tons of cane per crop. The main bottlenecks were identified and possible solutions proposed and, from the mass balances, the quantity and nominal capacity of the equipments were determined, and details of these equipments were presented when possible. Continual sterilization was used for the biomass, using direct flow of saturated steam in an endless thread apparatus, followed by refrigeration in a rotating drum. The inoculum was proposed to be produced by SSC in tray bioreactors. The mixture sugarcane bagasse-wheat bran would be mixed and inoculated in a rotating drum. The production of enzymes would take place by SSC in packed-bed bioreactors and an endless thread would be installed in it for the charge and discharge of biomass and to provide physical structure and air to the cultivation medium. Water would be added to the cultivated biomass to extract the enzymes in an agitated vessel, and the enzymatic extract would be separated from the biomass in a vacuum rotating drum. The enzymes would be produced in 20 bioreactors of 150m3 each, and the total enzyme activity produced would be of 8.45 10 10 FPU per crop and 4.59 105 FPU/m3 of enzymatic extract, whose expected application provides 10 % of the demand for sugarcane bagasse available for hydrolysis per crop.
Descrição
Palavras-chave
Etanol de segunda geração, Celulases, Cultivo em estado sólido, Produção industrial, Balanço material, Fluxograma de processo, Second-generation ethanol, Cellulases, Solid-state cultivation, Industrial production, Material balance, Process flowchart