No abstract

In this work, we performed recovery of ethanol from a fermentation broth of banana pseudostem by pervaporation (PV) as a lower‐energy‐cost alternative to traditional separation processes such as distillation. As real fermentation systems generally contain by‐products, it was investigated the effects of different components from the fermentation broth of banana pseudostem on PV performance for ethanol recovery through commercial flat sheet polydimethylsiloxane (PDMS) membrane. The experiments were compared to a binary solution (ethanol/water) to determine differences in the results due to the presence of fermentation by‐products. A real fermented broth of banana pseudostem was also used as feed for the PV experiments. Seven by‐products from fermented broth were identified: propanol, isobutanol, methanol, isoamyl alcohol, 1‐pentanol, acetic acid, and succinic acid. Moreover, the residual sugar content of 3.02 g/L1 was obtained. The presence of methanol showed the best results for total permeate flux (0.1626 kg·m−2·h−1) and ethanol permeate flux (0.0391 kg·m−2·h−1) during PV at 25°C and 3 wt% ethanol, also demonstrated by the selectivity and enrichment factor. The lowest total fluxes of permeate were observed in the experiments containing the acids. Better permeance of 0.1171 from 0.0796 kg·m−2·h−1 and membrane selectivity of 9.77 from 9.30 were obtained with real fermentation broth than with synthetic solutions, possibly due to the presence of by‐products in the multicomponent mixtures, which contributed to ethanol permeation. The results of this work indicate that by‐products influence pervaporation of ethanol with hydrophobic flat sheet membrane produced from the fermented broth of banana pseudostem.

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RESUMO -A produção de etanol a partir de resíduos da bananicultura difere da que utiliza a cana-de-açúcar como biomassa (empregada no Brasil) no que se refere ao uso de frutos rejeitados pois além dos microrganismos, há presença de uma fração de sólidos suspensos conferindo ao caldo menor fluidez. Este trabalho teve por objetivo caracterizar a fase líquida do fermentado utilizando-se três diferentes métodos de separação sólido-líquido (centrifugação, microfiltração e filtração a vácuo). Foram analisados os seguintes parâmetros: concentração de etanol e outros álcoois, açúcares redutores, ânions, carbono, nitrogênio, sólidos voláteis e totais, demanda química de oxigênio, turbidez assim como a massa após o processo. Os resultados apresentaram pequenas diferenças na composição do fermentado quando os processos de microfiltração e filtração a vácuo foram comparados com o convencional (centrifugação), indicando vantagens para a posterior recuperação do etanol.