Optimization of variables from the anaerobic digestion process of cheese whey in biogas production

Abstract

To reduce the consumption of fossil fuels and to have competitive prices of biogas in the energy market, it is necessary to have bioprocesses with low cost and high efficiency of production. This study demonstrates that biogas production and methane yield can be increased optimizing some of the variables of the anaerobic digestion process of cheese whey. The initial conditions of process variables, such as initial substrate concentration, initial inoculum concentration, and initial pH were evaluated and optimized using a central composite design. The optimal conditions for the maximum values of methane yield (469.75 ± 3.25 mL CH4/g SV) and biogas production (331±1.13 mL) were the following: initial substrate concentration of 24.6 g/L, initial inoculum concentration of 22.4 g/L, and initial pH of 7.1. The analysis of volatile fatty acids indicated that the formation of methane in biogas is mainly due to metabolic transformation of acetate by the acetoclastic methanogenesis pathway. The obtained results show that using cheese whey as substrate and under the optimal conditions obtained, the bioprocess developed in this study can be a new industrial biotechnological option for the production of biogas.