Anaerobic Biological Treatment of Vinasse for Environmental Compliance and Methane Production.

Abstract

The energy crisis resulted in increasing awareness that alternative sources of energy should be considered. During this time, Brazil implemented ethanol production from sugarcane as biofuel. However, during this process, large amounts of residues are generated, such as vinasse. This residue can be treated anaerobically to generate methane as a source of bioenergy with the use of sequencing batch reactors operated with immobilized biomass (AnSBBR). In this work, tests were conducted in an AnSBBR laboratory-scale reactor, and the main results regarding the kinetic model fitting and performance of substrate consumption (83 %), methane content in the biogas (77 %), applied organic load (5.54 g COD L(-1) day(-1)), methane productivity (973 N-mL CH4 L(-1) day(-1)), and yield (9.47 mol CH4 kg COD(-1)) show that AnSBBR is a promising technological alternative. After tests conducted in a laboratory-scale reactor, an industrial reactor was scaled and was also operated in a sequencing batch with immobilized biomass (AnSBBR) for the anaerobic treatment of vinasse with the goal of generating methane and environmental suitability to further disposal in soil. The calculations were performed based on data from a sugar and alcohol plant located in São Paulo, Brazil. This study proposes to the operation of the industrial scale reactor was the association of four AnSBBR (each one with a volume of 15849 m(3)) operating in parallel (with a feeding and discharge time of 4 h and a reaction time of 8 h), with the goal of adapting the treatment system from a discontinuous operation to a continuous operation. In this industrial scenario, the methane production was estimated at 1.65 × 10(6) mol CH4 day(-1), and the energy was approximately 17 MW, increasing the possible energy recovery contained in sugarcane from 93 to 96 %.