Evaluation of biogas production rate and biochemical changes in pig dung used in a simple mobile bio-digester

The rate of biogas generation and biochemical changes in pig dung used in a simple mobile biogas digester designed and constructed at the Department of Environmental Technology, Federal University of Technology Owerri, Nigeria were evaluated. Measurable gas production started 4 days after feeding the digester with pig dung with daily gas volume at this point standing at 0.005m3 and stabilizing at 0.035m 3 for the 5 th and 6 th day. Thereafter, daily gas production dropped and was fluctuating between 0.001m3 and 0.002m3 from the 7th to the 22nd day, and then rose to 0.003m3 on the 23rd day and maintained a daily production volume of 0.009m3 from the 24th to 27th day. A constant volume of 0.008m3 produced for the next 5 days. From the 33rd day the daily gas volume began to increase exponentially to an optimum volume of 0.070m3 on the 42nd day after feeding the digester. All biochemical parameters of the dung analyzed such as Moisture (%), Ether Extract (%), Ash (%), Crude Protein (%), Crude Fiber (%), Crude Fiber (%), Nitrogen (%), Phosphorous mg/100gm and Potassium mg/100mg, showed significant decreases in values after 37 days of digestion except crude fiber value which increased significantly (