Waste gas from the fermentation of bioethanol production consists of high carbon dioxide concentration. The CO2 emissions cause global climate change. The conversion of carbon dioxide to chemical products or fuels is an interesting solution for reducing the amount of carbon dioxide emissions. The methane synthesis via carbon dioxide methanation reaction has attracted much attention. The suitable operation of the methanation process for methane synthesis from waste gases should be studied. This work aims to investigate the methane production from the waste gas of the fermentation process. The composition of impurities in waste gases on the performance of the methanation process is investigated. The effects of hydrogen to carbon dioxide ratio and operating temperature on the carbon dioxide conversion and methane yield of the methanation are also studied. The simulation results from the thermodynamic analysis show that the methane yield of the methanation from waste gases is 3.11 - 4.61 % higher than that from pure carbon dioxide in the temperature range of 300 - 500 °C. The methane yield of the methanation process decreases with increasing temperature. The increase in the hydrogen to carbon dioxide ratio of 1 to 4 and the operating pressure of 1 to 8 bar have a significant effect on the enhancement of carbon dioxide conversion and methane yield.