Composition of TR1, TR2 and MR1, MR2 were shown in Table 2. Natural inoculum (compost) collected from a core of compost pit (where the temperature was in the range 45–50 °C) and cattle dung slurry was collected from an operating biogas plant were used as inoculum to initiate the fermentation process for thermophilic and mesophilic reactors, respectively