Produção de biohidrogênio por fementação escura a partir do bagaço de cana de açúcar: análise comparativa dos principais métodos pré tratamentos e seus efeitos no rendimento do processo

Abstract

The increasing global demand for energy and the need to reduce greenhouse gas emissions have intensified the search for renewable energy sources capable of meeting sustainability principles. In this context, biohydrogen has emerged as a promising energy alternative due to its potential to utilize agro-industrial residues while contributing to the reduction of dependence on fossil fuels. Among the available feedstocks, sugarcane bagasse has considerable potential because of its wide availability in Brazil and its high content of structural carbohydrates that can be converted into hydrogen through dark fermentation. However, the high recalcitrance of this lignocellulosic biomass, resulting from the presence of lignin, limits its biodegradation, making the application of pretreatment methods essential to increase the accessibility of cellulose and hemicellulose to fermentative microorganisms. The main pretreatment methods applied to lignocellulosic biomass include physical, chemical, physicochemical, and biological processes, whose effectiveness is directly associated with operational parameters such as pH, temperature, inoculum, and hydraulic retention time, all of which influence the performance of the fermentative process. The results demonstrated that alkaline and physicochemical pretreatments were more effective in promoting partial lignin removal and increasing cellulose fiber exposure, thereby enhancing the release of fermentable sugars. In the case study, the combined application of an alkaline solution and ultrasound promoted structural modifications confirmed by X-ray diffraction and Fourier-transform infrared spectroscopy, resulting in an approximately thirty-five percent increase in biohydrogen production and favoring the formation of acetic and butyric acids, metabolites associated with higher hydrogen yields. These findings demonstrate that the integration of efficient pretreatment strategies with appropriate control of operational conditions is a determining factor in maximizing the conversion of sugarcane bagasse into biohydrogen, reinforcing the potential of this biomass as a feedstock for sustainable energy production and the development of biorefineries.