Biogas production by sugar cane vinasse anaerobic digradation: investigation of hydraulic and organic rates applied to the up flow anaerobic sludge blanket reactor for process optimization

Abstract

The technological competence of the Brazilian sugar and alcohol industry is globally recognized. However, scientific and technological research are still needed to improve the recovery of the energy contained in ethanol production by-products. From the energy that produced from sugar cane, 40% are in the form of ethanol but the bagasse and the vinasse could result in a surplus of 31% and 5% respectively. The bagasse is already used to cover the energy required at the sugar and ethanol mill, however the remaining energy contained in the vinasse is not negligible in the overall energy balance. Anaerobic digestion is a viable option to transform the vinasse into biogases. These biogases are similar to natural gas, containing mostly methane that can be burnt to produce heat, electricity or mechanical energy. Previous knowledge obtained from research using different reactor configurations indicates that there are still difficulties to overcome in order to keep steady production of biogas using high rate reactors, which are the most economical ones when the amount of vinasse is taken into account. Thus, this research aims to study the effect of hydraulic and organic loads using pilot scale reactors to define rational design criteria for such reactors. Factors such as the effect of nutrients, inhibition and alkalinity balance will be studied in conjunction with the reactor loading. (AU)