Effects of vinasse concentration on biogas production: An experimental work and case study in the context of RenovaBio in Brazil

Vinasse composition varies throughout the year, which may affect methane production. To assess the effects of the chemical oxygen demand (COD) on methane yield, we fed a reactor with increasing organic loading rates ranging from 1.15 to 4.56 g COD l−1 day−1. In the second part of this study, we compared two scenarios for the state of Sao Paulo: 1) average vinasse COD; 2) ideal vinasse COD (38.8 g l−1). We found that the maximum methane yield was obtained at an OLR of 2.66, equivalent to a COD of 38.8 g l−1, and could increase the sugarcane mill energy production by 15.6 %. Considering the state of Sao Pauo, if all the vinasse was used to produce biogas, 3.9 million tons CO2eq (CBIOs) emission would be avoided yearly. Concentrating all the vinasse to the ideal COD would increase it by 3.2 %. Therefore, vinasse concentration would have little effects on a state-scale.