Study of Mesophilic Anaerobic Digestion of Cow Manure in Middle-Scale Biogas Plant

摘要

Biogas production in anaerobic digestion in middle scale units will be typically performed under mesophilic conditions in China when used for producing bioenergy and treating agricultural waste such as animal manure. A study has been made on biogas fermentation from cow manure in a 100 1113 anaerobic digester equipped with a mechanical agitator under controlled temperature (35±2 °C) for this purpose. TS concentration should be controled more than 5%. The biogas generated from the anaerobic digester had the methane concentration as high as 60% (vN) at TS concentration varied from 5% to 6o% after the 10th day. During the startup period, concentrations of TN, TP and COD decreased gradually, but concentrations of NH4-N and VFA increased. However concentrations of these composition varied narrowly at normal operating time. The pH was stabilized between 7.19 and 781 after the 8th day, which suggests that the anaerobic system of cow manure would adjust itself and stabilize pH. The biogas production rate exceeded 110 m3/d at optimum operating temperature(35±2 C). Biogas with 60% CH4 or higher was produced under optimum operating condition.