摘要：Biogas is a renewable fuel that produced through a process of anaerobic fermentation of a mixture of cow dung and water. The process of formation of methane gas occurs in a digester reactor with a capacity of 3500 kg/batch during a certain fermentation time with the help of anaerobic bacteria. This research studied effect of the comparison of cow dung and water as well as the number of microbes added. The process of formation of biogas run at varying of cow dung with water and microbes added. Fermentation process was running 16 days by varying the variables. Furthermore, every four days observed, and recorded pressure in the digester, biogas product was analyzed its content of methane gas were formed. Relatively good results were taken on cow dung and water ratio of 1: 1 with the addition of microbes as much as 50 ppm with a time of fermentation for 12 (twelve) days produce biogas of 5.1 m 3/batch with contents of methane about 74 %, carbon dioxide 19 %, and residual gas of 7 %.
