Resumo: O aumento do consumo da água de coco leva a uma maior geração de resíduos, impactando em problemas ambientais e merecendo atenção de pesquisadores para o aproveitamento desta biomassa. Este trabalho avalia a composição da fibra da casca de coco verde, na forma in natura e após pré-tratamento ácido e alcalino, investigando as características lignocelulósicas desta biomassa como mais uma alternativa para o desenvolvimento e produção do etanol. Observou-se elevada concentração de lignina (40,10%), proporcionando alto grau de durabilidade e resistência ao material, e significativa quantidade de celulose (24,70%), oferecendo boas condições para sua utilização na produção de etanol de segunda geração. O pré-tratamento alcalino, apesar da significativa perda em celulose, apresentou maior solubilização de lignina (80%), tornando-se o mais viável para estudos da produção de etanol 2G.Palavras-chave: Aproveitamento, casca de coco, celulose, pré-tratamento.

Problems related to the use of fossil fuels and greenhouse gas emissions have become global concerns. To address this issue, the strategy adopted in the present study was to use Ananas comosus residues as a source of fermentable carbohydrates to produce second generation ethanol and briquettes. The demand for biofuel is addressed in the present study by the integrated processing of several stages of treatment of the lignocellulosic substrate: chemical characterization, pretreatment, enzymatic hydrolysis and fermentation. It was verified under the conditions used that the enzymatic hydrolysis liberated after 72 hours 58.44 and 21.91 g L-1 of glucose and xylose, respectively. Conversion of the sugars in the fermentation step resulted in 18.80 g L-1 ethanol in 24 hours. The briquettes produced from the remaining solid fraction of the enzymatic hydrolysis presented a calorific value of 18.41 kJ kg-1 .

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In this study, the possibility of increasing fermentation efficiency of Saccharomyces cerevisiae on sugarcane bagasse (a type of lignocellulosic waste) was analyzed. Sugarcane bagasse was subjected to hydrothermal and acidic pre-treatment. Next, the enzymatic hydrolysis of raw biomass and each pre-treated biomass was performed using CellicCtec® enzymatic complex to obtain sugarcane hydrolysate, hydrothermal hydrolysate and acidic hydrolysate. Next, these were fermented by S. cerevisiae to check if the by-products of enzymatic hydrolysis, furfural and acetic acid had an inhibitory effect on fermentation efficiency. Next, each pre-treated biomass was subjected to detoxification involving activated charcoal. Each detoxified biomass was tested for fermentation efficiency. The lignocellulosic composition for sugarcane hydrolysate, hydrothermal hydrolysate and acidic hydrolysate, varied significantly, and were found to be, for cellulose 36.7%, 27.7% and 63.7% respectively; for hemicellulose 22.2%, 4.4% and 12% respectively; and for lignin 21.2%, 27.7% and 28.7% respectively. The presence of furfural and acetic acid had a strong influence on the fermentation efficiency of S. cerevisiae, and affected the consumption of sugars in each biomass by more than 90%. Further, we found that the detoxification process increased fermentation efficiency by 12.7% for the hydrothermal hydrolysate while for the acidic hydrolysate no significant difference was observed. This study showed that fermentation with greater efficiency is viable through the combined use of hydrothermal pre-treatment and detoxification. This combination of methods also causes less pollution as compared with the method involving acid pre-treatment due to the reduced number of effluents produced.

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