Efficient biogas production from cattle manure in a plug flow reactor: A large scale long term study.

In this study, a large-scale plug flow reactor has been operated at a hydraulic retention time of 25 d with substrate concentration of total solids (7-10%) under a temperature of 37-40 °C with a working volume of 3.85 × 104 m3 and dispose 1504 m3/d of waste for three years. The average monthly biogas production was 7.45 × 104 m3. At stable stage, the volume biogas, methane production rate and methane content reached 1.07 m3/m3·d, 0.58 m3/m3·d and 56.4%, respectively. Moreover, the specific biogas and methane yields of substrate removal efficiency were up to 0.39 m3/kg VS, 0.22 m3/kg VS and 59%, respectively. Among the bacteria, the genera Draconibacteriaceae, Ruminofilibacter, Cloacimonetes and vadinBC27, Ruminiclostridium and Treponema_2 dominated in digestate. The achaeal was dominated by methanogens genera Methanosarcina and Bathyarchaeota. Long-term operation in large scale demonstrated technological potential and industrial application of cattle manure treatment for biogas production.