Effect of Substrate on Biogas Yield

Biogas technology converts biological matter or biological waste (substrate) into energy and simultaneously helps to improve the quality of life and the environment. The effect of substrate on biogas yield was studied by using different substrate in laboratory scale experiment using water displacement method to monitor the volume of biogas produced. The substrates used are waste tomatoes, waste fluted pumpkin leaves, chicken manure, sheep manure and cow dung. The cumulative biogas produced by each of the substrate was monitored and recorded over a period of 22 days. the results show that sheep dung gave the highest cumulative volume of biogas per 100 g of substrate of 240 ml followed by cow dung 200 ml and the least being waste tomatoes and chicken manure with cumulative volume of 170 ml each. Analysis of the biogas produced indicated that the average content of methane is 65.34 mol%, carbon dioxide 22.81mol%; other components present are; hydrogen 7.49 mol%, Oxygen 0.95 mol%, Nitrogen 3.39 mol% and trace amount of carbon monoxide and water vapor. Hydrogen sulfide was not detected. Based on these results it can be conclude that sheep manure gave the highest cumulative volume of biogas and that the biogas produced from all the substrates is free from hydrogen sulfide.