As it is reported, the inoculums could have a relatively higher effect on the oil digestion and degradation than the other factors because the amount of inoculums is related to the total activity of lipase. And it three different inoculum dosages were studied in the following experiment: 9 wt%, 6 wt% and 3 wt%. Fig. 1 illustrates the experimental data of daily biogas yield and methane content. As can be seen from the Fig. 1: