Estratégias de pré-tratamento de biomassa lignocelulósica para melhorar a produção de biogás e bioquímicos em biorrefinarias

Abstract

The search for sustainability and for alternative sources that minimize the environmental impacts associated with conventional sources of energy and chemicals has been growing and gaining more and more space in the current world scenario. Studies regarding the search for profitable and effective solutions for the reuse of waste have been on the rise in recent years, especially those that use lignocellulosic biomass from agribusiness. These wastes can be treated through anaerobic digestion as a way to reduce environmental impacts and energy use. However, due to the complexity of the existing interactions in the lignocellulosic structure, it is necessary to use pre-treatments that perform the dissociation or disruption of constituents (cellulose, lignin and hemicellulose) of lignocellulosic biomass. In this context, this work aims to evaluate the pretreatment methods developed for the main feedstocks in biorefineries, which is a crucial step to trigger and enable the production of biogas resulting from anaerobic digestion, highlighting the effectiveness, limitations and challenges of these techniques. Among the existing techniques, microwave, ultrasonic and combined pretreatment are promising, mainly for their high effectiveness on a variety of lignocellulosic biomass. For the same substrate, wheat straw, the steam explosion method resulted in the highest methane yield by providing a 94.5% increase in gas production. Regarding hydrogen, the microwave pretreatment showed higher production compared to other methods, producing a total of 131.7 mL of H2/g substrate. Although the studies reported in this review show the increase in biogas yield when the pretreatments are used, the use of these techniques on an industrial scale is still a challenge due to the obstacles concerning the process and the structure of the lignocellulosic biomass.