Anaerobic co-digestion of biogas effluent and sugarcane filter cake for methane production

Abstract

Proportions of biogas effluent, sugarcane filter cake, and anaerobic sludge for methane production were optimized in batch fermentation using a mixture design with the D-optimal design method. The highest methane yield (MY) of 175.1 mL CH4/g volatile solid (VS) was achieved at a biogas effluent and filter cake of 30.00 and 30.00 g VS/L, respectively. Results suggested that the methane production could occur by normal floras in biogas effluent and filter cake without the addition of inoculum. The data from batch experiments were used to evaluate the hydraulic retention time (HRT) by the first-order kinetic model. The optimum proportions and predicted HRT of 30 days were further used to determine their efficacy in generating methane in the semi-continuous fermentation process using the continuous stirred tank reactor (CSTR). It was confirmed that the optimum proportions and HRT of 30 days gave a maximum MY of 92.8 mL CH4/g VS and methane production rate of 185.9 mL CH4/L day. Graphical abstract: [Figure not available: see fulltext.]