Simulation of Methane Production Process from Livestock Wastes into a Batch Bioreactor

 Considering the importance of environmental protection and necessity of using new energy sources and innovative fuels, using of renewable energies have been a great concern. Due to this necessity, in this study, mathematical modeling and simulation of a batch bioreactor to produce methane from livestock waste was investigated numerically.

The relationship between microorganism’s growth rate and substrate concentration were established by Monod model. The equations of mathematical model were solved with fourth order Rung Kutta. The effect of initial microorganisms’ concentration on methane production was also investigated. Initial concentration of substrate and microorganisms are 51.74 g/L and 1.61 g/L, respectively.

The results revealed that the mathematical model average deviation from experimental data is 8.53%. The amount of methane produced after 70 days is equal to 10.29 g/L. The substrate disintegration and methane production are a function of substrate retention time. Enhancement in the initial concentration of microorganisms causes methane gas production in less time. The amount of methane gas produced is independent of initial microorganisms’ concentration.

The model which presented in this study could be used to predict the time required to carry out the reaction, ooptimum performance of bioreactor, the relevant process equipment design, scale up of equipment such as digestive and appropriate control of operation to produce high-purity methane and higher volume of biogas in the bioreactor.