Anaerobic Digestion of Cow Dung with Rumen Fluid

Production of biogas from agricultural and animal wastes is one of the viable options to mitigate the scarcity of energy and hazards of fossil fuels to both human and ecology. Therefore, this project work was on generation of biogas using cow dung and rumen fluid as co-substrate. A biogas digester with a capacity of 105 liters was used to produce the gas. The substrate (cow dung and rumen fluid) was mixed in the ratio 3:2 and water to substrate ratio of 2:1 was used. The digester was stirred thrice daily to avoid scum formation in the digester and to allow for easy escape of the gas produced. The retention time used for this experiment was 42 days during which the daily internal temperature readings were taken in order to determine temperature variations and also to determine the effect of heat on the production rate. A rubber hose was connected to the digester gas outlet located at the top of the digester and the other end of the rubber hose was connected to a PVC Tyer tube provided for storing the gas generated. The gas produced was collected and taken to the laboratory for chemical analysis. The results showed that biogas yielded consists of 57.98 % of methane (CH4), 39.99 % of carbon dioxide (CO2), 0.10 % of oxygen (O2), 0.01 % of hydrogen sulphide (H2S) and 0.01% of water vapour. The methane has the highest percentage, which represents the main source of energy and oxygen having 0.10 %, which shows that the process was purely carried out under anaerobic condition. Result of this study showed that methane has the highest percentage and generally cow dung with rumen fluid easily lent itself to process of anaerobic digestion.