Anaerobic digestion of vinasse and pentoses liquor in integrated biorefineries of 1st and 2nd generation

Abstract

The growing need to expand the use of renewable energy sources in a sustainable manner has driven the production of biofuels worldwide. Within this scenario, Brazil stands out with bioethanol from sugar cane. The ethanol production of 1st generation is already established on a large scale in the country. With the prospect of expanding the production of this biofuel, ethanol of 2nd generation emerges as an interesting alternative, because it would be produced from sugarcane bagasse previously used in the 1st generation. In this way, the productivity of ethanol volume could be increased without expanding the area of cane planted. However, for achieving the full sustainability of the production process, the treatment and use of generated wastewaters must be considered. On the one hand, the stillage generated in large volumes during the distillation of ethanol and, on the other hand, the liquor pentoses from the pre-treatment bagasse represent serious environmental problem if disposed improperly. The anaerobic digestion is presented as a sustainable option for treatment. It combines the environmental suitability of these wastes to energy generation through the production of hydrogen and methane, as well as generating value-added products. This design is suited to the concept of a biorefinery, integrating ethanol production and recovery of energy and by-products. However, gaps on anaerobic digestion of stillage generated in the production of bioethanol from sugar cane hamper the implementation and expansion of this technology. The obstacles are even greater regarding the liquor pentoses. There is no information available in the literature on the digestion of this current, except the attempts of its use to produce ethanol or other products in a biorefinery. Thus, this research aims at the collection of data on the anaerobic digestion of stillage and liquor pentoses, for modeling and simulation of this process in an integrated virtual biorefinery of 1st and 2nd generation.