Simultaneous evaluation of the effect of mixing efficiency on power consumption and methane production in an anaerobic digester with different wastewaters

This study simultaneously examines the effect of mixing rate on power consumption and methane production in a stirrer anaerobic reactor. The numerical simulation is carried out using the finite volume approach and validated against available experimental data. The methane production rate is determined using governing equations in the anaerobic digestion (AD) process. The results showed that a 60% increase in the mixing rate of the system (from 50% to 80%) in the wastewater with concentration of 14,549 (mgl^-1) increased the methane production rate by about 35% and increased the power consumption of the system by about 13 times. Among the 144 cases studied, the best stirrer model is figured out as the optimal model by applying an index of performance coefficient and also this model is investigated with scale-up criteria in larger sizes. A novel equation for evaluating the power production value is suggested in real digesters.