Anaerobic Treatment of Vinasse from Sugarcane Ethanol Production in Expanded Granular Sludge Bed Bioreactor

Abstract

The sugarcane vinasse cause an environmental problem, due they do not a previous treatment and are discharged directly into the environment. For this reason, the main aim of this project was to evaluate the anaerobic digestion in expanded granular sludge bed (EGSB) bioreactor as a sustainable alternative for the treatment of sugarcane vinasse. In addition, the production of biogas and biochemical methane potential (BMP) were determined. Vinasse was characterized physico-chemically and its parameters such as chemical oxygen demand (COD), biochemical oxygen demand (BOD5), pH, metal ions, among others were evaluated. Simultaneously, an anaerobic inoculum was acclimated in a batch bioreactor to assimilate the vinasse during 75 days. After that, the EGSB bioreactor was started-up with the previously acclimated inoculum and evaluated to determinate the BMP, biogas production and COD removal. The EGSB bioreactor was operated with a hydraulic retention time (HRT) of 7 days under stable conditions (i.e., alkaline factor of 0.24, pH 7.2 and temperature 26°C) for 140 days, generating a maximum chemical oxygen demand (COD) removal efficiency close to 75%, biogas production contained 76% methane concentration which generates a calorific power of 6507 kcal/m3 with an average methane production of 4.2 L of CH4/day and BMP of 244.64 mL CH4/gCOD. According to the obtained results, the anaerobic EGSB bioreactor can be a solution to the environmental challenges that this agro-industry confronts, since could be a sustainable alternative to simultaneously solve the environmental pollution caused by vinasse and produce bioenergy for the operation in the same agro-industry.