RESUMO

This study evaluated the effects of the temperature and pressure used when compacting banana leaves on viscoelastic properties and briquette quality. Banana leaves with 12.4% of humidity were milled at two ranges of average particle size. The briquetting was carried out in a cylinder-piston device coupled to a universal mechanical test machine, under different compacting temperatures (30 and 120 °C) and pressures (20, 40 and 60 MPa). Several parameters, including compacting module, porosity index, final density, critical density, compacting energy, compression ratio, higher heating value, and energy density, were investigated. The banana leaf particles smaller than 1.7 mm performed better during compaction, with low compacting resistance. Temperature showed less influence on final density than pressure. The increase of pressure contributed to decreasing the compacting module and to achieving denser briquettes. It was not necessary to apply high temperature to obtain briquettes with high final density and energy density. The optimum briquetting process parameters identified can be used to produce briquettes from banana leaves at an industrial scale with an extruder. Briquetting adds value to banana leaf waste and reduces environmental pollution.

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RESUMO

This study is the first report that focuses on investigating the effects of torrefaction on the bioenergy-related properties, combustion behavior, and potential emissions of banana leaf waste (BLW). Experiments were first conducted in a bench-scale fixed-bed reactor operating at light (220 °C), mild (250 °C), and severe (280 °C) torrefaction conditions to torrefy the raw BLW. Torrefaction pretreatments reduced the weight of the raw BLW by about 60%, but the resulting solid biofuel can preserve up to 77% of the energy content of the raw biomass. It was found that torrefied BLW contains more concentrated fixed carbon than the raw BLW, volatile matter content of up to 59.8 wt.%, and a higher HHV of up to 20.7 MJ kg-1 with higher concentrations of carbon, nitrogen, and ash. Bulk density increased 13.0% over the raw BLW, and the torrefied BLW became a solid biofuel with 51.5% greater energy density under the severe torrefaction condition. The upgrading of BLW by torrefaction enhanced its combustion performance in terms of comprehensive combustion, ignition, burnout, and flammability indices. Compared with commercial hard coal, BLW torrefied at the mild condition (250 °C) had lower potential emissions per unit of energy, 25.3% less CO2 emission, 3.1% less CO emission, 96.4% less SO2 emission, and 18.4% less dust emission, except for NOX emission. This study conclusively indicates that BLW after torrefaction has enhanced bioenergy-related properties, improved combustion performance, and reduced emissions potential, proving to be a promising method for its valorization.

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RESUMO

The biosurfactant production is characterized by high costs with substrates, which does not make them sufficiently competitive against synthetic surfactants. The insertion of alternative sources of low cost, especially agro-industrial residue, is an excellent alternative to make this competitiveness viable. An alkaline pretreatment was used to extract the hemicellulose from corncob in order to enhance its C5 fraction, common to vegetable biomasses. The hemicellulosic corncob liquor was used with glucose and mineral salt solution as carbon and nutrients sources in a fermentation process for the growth of Bacillus subtilis. It was performed a 23 full factorial design to determine the best conditions for the surfactin production in relation to the following response variables: surface tension reduction rate (STRR) and emulsification index (EI24), from which were obtained two optimized bioproducts under specific conditions. The optimized biosurfactants found to be effected presenting a critical micelle concentration of 100 mg.L-1 and a maximum bioremediation potential of 85.18%, as well as maximum values of 57.38% and 65.30% for STRR and EI24 variables, respectively. Overall results pointed for a successful commercial application for the surfactin produced.

RESUMO

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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Cellulases constitute an enzymatic complex involved in the cellulose hydrolysis ß-1, 4-glycosidic linkages to release of glucose. Therefore, its application to degrade agro-industrial residues becomes relevant, since glucose is a product of industrial interest, aiming at its conversion into biocommodity production (e.g., enzymes, bioethanol and other value-added biochemicals). Thus, in natura Soybean hulls as well as fractions obtained from its alkaline, autohydrolysis and organosolv pretreatments were used as carbon sources in submerged fermentation processes to evaluate the cellulase-inducing capacity using a Penicillium sp. strain. Results showed an inductive effect on the production of 0.130 and 0.066 U/mL for CMCase and FPase, respectively, using 1% of the in natura residue. Regarding the fraction obtained from soybean hulls pretreated by autohydrolysis and organosolv, avicelase and ß-Glucosidase displayed a production of 0.200 and 0.550 U/mL, respectively. Therefore, the use of pretreated Soybean hull revealed its potential as an alternative carbon source for the cellulase production, which may contribute significantly to biotechnological purposes by adding value to an agro-industrial residue.

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The majority of the textile dyes are harmful to the environment and potentially carcinogenic. Among strategies for their exclusion, the treatment of dye contaminated wastewater with fungal extract, containing lignin peroxidase (LiP), may be useful. Two fungi isolates, Pleurotus ostreatus (PLO9) and Ganoderma lucidum (GRM117), produced the enzymatic extract by fermentation in the lignocellulosic residue, Jatropha curcas seed cake. The extracts from PLO9 and GRM117 were immobilized on carbon nanotubes and showed an increase of 18 and 27-fold of LiP specific activity compared to the free enzyme. Also, LiP from both fungi extracts showed higher Vmax and lower Km values. Only the immobilized extracts could be efficiently reused in the dye decolourization, contrary, the carbon nanotubes became saturated and they should be discarded over time. This device may offer a final biocatalyst with higher catalytic efficiency and capability to be reused in the dye decolourization process.

RESUMO

Banana waste has the potential to produce ethanol with a low-cost and sustainable production method. The present work seeks to evaluate the separation of ethanol produced from banana waste (rejected fruit) using pervaporation with different operating conditions. Tests were carried out with model solutions and broth with commercial hollow hydrophobic polydimethylsiloxane membranes. It was observed that pervaporation performance for ethanol/water binary mixtures was strongly dependent on the feed concentration and operating temperature with ethanol concentrations of 1-10%; that an increase of feed flow rate can enhance the permeation rate of ethanol with the water remaining at almost the same value; that water and ethanol fluxes was increased with the temperature increase; and that the higher effect in flux increase was observed when the vapor pressure in the permeate stream was close to the ethanol vapor pressure. Better results were obtained with fermentation broth than with model solutions, indicated by the permeance and membrane selectivity. This could be attributed to by-products present in the multicomponent mixtures, facilitating the ethanol permeability. By-products analyses show that the presence of lactic acid increased the hydrophilicity of the membrane. Based on this, we believe that pervaporation with hollow membrane of ethanol produced from banana waste is indeed a technology with the potential to be applied.

Assuntos