Produção de etanol de segunda geração utilizando bagaço de sorgo sacarino, forrageiro e biomassa
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Data
2017-03-20
Autores
Freita, Lidyane Aline de [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O etanol de cana-de-açúcar vive uma crise devido, principalmente, a não expansão dos processos fermentativos que terminam por depender de apenas uma fonte e que ainda apresenta o agravante de ter que ser segregado à produção de açúcar. Desta forma, o sorgo surge como cultura energética, como matéria-prima para produção de etanol, tanto do ponto de vista agronômico quanto industrial. O sorgo apresenta colmos ricos em açúcares fermentáveis, semelhantes à cana-de-açúcar. Objetivou-se com a presente pesquisa avaliar a potencialidade de 3 genótipos de sorgo (sacarino, forrageiro e biomassa) para produção de etanol 2G, com ênfase na caracterização do bagaço antes e após pré-tratamento ácido e hidrólise enzimática, e na fermentação dos hidrolisados por duas leveduras, sendo a LJ3, fermentando as pentoses e as hexoses com Saccharomyces cerevisiae (PE-2). Avaliou-se a composição dos bagaços dos 3 genótipos de sorgo em relação aos nutrientes, além da análise de microscopia eletrônica para visualização das biomassas após os tratamentos realizados. Os resultados evidenciaram a eficiência do pré-tratamento e da hidrólise enzimática possibilitando a recuperação dos açúcares presentes no bagaço de sorgo para composição do mosto a ser fermentado; a cepa LJ03 foi classificada como Pichia kudriavzevii, que apresentou habilidade para metabolizar pentoses e hexoses a etanol. A hidrólise enzimática foi eficiente e possibilitou a produção de 11,83; 12,28 e 7,79g etanol/kg bagaço m.s., para os genótipos sacarino, forrageiro e biomassa, respectivamente empregando a levedura PE-2. Observou-se nas análises de nutrientes dos bagaços dos diferentes genótipos de sorgo, que estes reduziram significativamente das biomassas in natura, para biomassa pré-tratada e após hidrólise enzimática. O poder calorífico (PCS, PCI e PCU) dos resíduos gerados na produção de etanol 2G, foi de 3811; 3902 e 3953Kcal.kg-1 respectivamente para o sorgo sacarino, forrageiro e biomassa. Para a produção de etanol 2G obteve-se rendimento total de 59,38; 45,33 e 25,53 litros de etanol.t-1 de massa seca respectivamente, e produção de 1.301,48, 964,82 e 805,52 litros de etanol/ha, respectivamente. O genótipo BRS508 (sacarino) foi o que apresentou maior produção de etanol de segunda geração em comparação aos BRS610 (forrageiro) e BD7605 (Biomassa).
Sugarcane ethanol is experiencing a crisis, mainly due to the nonexpansion of the fermentation processes that end up depending on only one source that still presents the aggravating factor of having to be segregated to the sugar production. In this context, sorghum emerges as an energy crop, as a raw material for the ethanol production, both from an agronomic and industrial point of view. Sorghum has stalks rich in fermentable sugars, similar to sugarcane. The objective of this research was to evaluate the potentiality of 3 genotypes of sorghum (sweet, forage and biomass) for the production of 2G ethanol, with emphasis on the characterization of bagasse before and after acid pretreatment and enzymatic hydrolysis, and in the fermentation of the hydrolysates by two yeasts, the LJ3 fermenting pentoses and Saccharomyces cerevisiae (PE-2) fermenting hexoses. The composition of the three sorghum genotypes in relation to the nutrients was evaluated, as well as the analysis of electron microscopy to visualize the biomass after the treatments. The results evidenced the efficiency of the pretreatment and the enzymatic hydrolysis allowing the recovery of the sugars present in the sorghum bagasse for the composition of the must to be fermented. The LJ03 strain was classified as Pichia kudriavzevii, which showed ability to metabolize pentoses and hexoses to produce ethanol. The enzymatic hydrolysis was efficient and allowed the production of 11.83; 12.28 and 7.79g ethanol/kg bagasse, for the sweet, forage and biomass genotypes, respectively, employing yeast PE-2. It was observed in the nutrient analyzis of the bagasse of the different sorghum genotypes, that nutrients reduced significantly of the in natura biomasses, for pretreated biomass and after enzymatic hydrolysis. The calorific value (HHV, LHV, and UHV) of the waste generated in the 2G ethanol production was 3811; 3902 and 3953Kcal.kg-1, respectively, for sweet, forage and biomass sorghum. The production of 2G ethanol there was a total yield of 59.38; 45.33 and 25.53 liters of etanol.t-1 of dry mass, respectively, and production of 1301.48, 964.82 and 805.52 liters of ethanol/ha, respectively. The BRS508 (sweet) genotype showed the highest production of second generation ethanol compared to BRS610 (forage) and BD7605 (biomass).
Sugarcane ethanol is experiencing a crisis, mainly due to the nonexpansion of the fermentation processes that end up depending on only one source that still presents the aggravating factor of having to be segregated to the sugar production. In this context, sorghum emerges as an energy crop, as a raw material for the ethanol production, both from an agronomic and industrial point of view. Sorghum has stalks rich in fermentable sugars, similar to sugarcane. The objective of this research was to evaluate the potentiality of 3 genotypes of sorghum (sweet, forage and biomass) for the production of 2G ethanol, with emphasis on the characterization of bagasse before and after acid pretreatment and enzymatic hydrolysis, and in the fermentation of the hydrolysates by two yeasts, the LJ3 fermenting pentoses and Saccharomyces cerevisiae (PE-2) fermenting hexoses. The composition of the three sorghum genotypes in relation to the nutrients was evaluated, as well as the analysis of electron microscopy to visualize the biomass after the treatments. The results evidenced the efficiency of the pretreatment and the enzymatic hydrolysis allowing the recovery of the sugars present in the sorghum bagasse for the composition of the must to be fermented. The LJ03 strain was classified as Pichia kudriavzevii, which showed ability to metabolize pentoses and hexoses to produce ethanol. The enzymatic hydrolysis was efficient and allowed the production of 11.83; 12.28 and 7.79g ethanol/kg bagasse, for the sweet, forage and biomass genotypes, respectively, employing yeast PE-2. It was observed in the nutrient analyzis of the bagasse of the different sorghum genotypes, that nutrients reduced significantly of the in natura biomasses, for pretreated biomass and after enzymatic hydrolysis. The calorific value (HHV, LHV, and UHV) of the waste generated in the 2G ethanol production was 3811; 3902 and 3953Kcal.kg-1, respectively, for sweet, forage and biomass sorghum. The production of 2G ethanol there was a total yield of 59.38; 45.33 and 25.53 liters of etanol.t-1 of dry mass, respectively, and production of 1301.48, 964.82 and 805.52 liters of ethanol/ha, respectively. The BRS508 (sweet) genotype showed the highest production of second generation ethanol compared to BRS610 (forage) and BD7605 (biomass).
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Palavras-chave
Sorghum bicolor, Pré-tratamento, Pichia kudriavzevii, Hidrólise enzimática, Hidrolisado ácido, Bioenergia