Biogas production in integrated 1st and 2nd generation sugarcane biorrefineries: fundamentals and operational aspects of the process

Abstract

The increase of ethanol productivity and bioenergy generation in sugarcane biorefineries are some alternatives to alleviate the crisis in the sugar-ethanol sector facing the current political-economic scenario of the country. In this scenario, R&D efforts have been concentrated to the 2nd generation ethanol production (2G), obtained from bagasse resulting from the sugarcane milling used for the traditional 1st generation ethanol (1G). The integration of the 1st and 2nd generation ethanol production (1G2G) promotes the increase of biofuel productivity per hectare of planted sugarcane, as well as the liquid waste streams, especially vinasse (derived from ethanol distillation) and pentoses liquor (from bagasse pre-treatment for producing 2G ethanol). As a sustainable way to dispose such wastes, there is the possibility of biogas production from the digestion of these streams, which promotes their environmental suitability in addition to enable the generation of energy through the use of biogas, which must be previously purified. This approach stimulates the 2G ethanol production, since the energy from biogas enables the partial release of bagasse from cogeneration. Although there is research on the anaerobic digestion of traditional vinasse from sugarcane, the same is not true for vinasse and pentoses liquor generated in the 2G case, with considerable gaps in the literature. Thus, this research aims to investigate the anaerobic digestion of 1G2G vinasse and pentoses liquor under fundamental and operational aspects, with a view to contribute to the implementation and expansion of such sustainable technology. A new proposal of biogas purification, integrated to microalgae cultivation, will also be explored, aiming to expand the possibilities of added-value products obtainment within the sugarcane biorefineries concept. The development of this project should be one of the primary sources of knowledge for the Brazilian 1G2G ethanol production allied to environmental responsibility. (AU)