BIOCONVERSION OF ORGANIC WASTES FOR SUSTAINABLE BIOGAS PRODUCTION USING LOCALLY SOURCED MATERIALS

Abstract

Global climate change and uncertainty of fossil fuel has led to the search for sustainable and environmentally friendly alternatives. This study is aimed at generation of biogas from organic wastes. Five digesters were constructed. Substrates such as food waste (FDW), fruit waste (FTW), and sawdust (SD) were used while cow dung (CD) was the inoculum. For digester CD, 6 kg of cow dung was mixed with 9 kg of water, while digesters CD + SD, CD + FDW, and CD + FTW were charged with 6 kg of cow dung, 9 kg of water, and 3 kg each of sawdust, food, and fruit waste, respectively. Digester with a mixture of CD + FDW + FTW + SD contained 6 kg of cow dung, 1 kg each of food waste, fruit waste, and sawdust, and 9 kg of water. The temperature fluctuated between 24°C and 40°C throughout the period of the experiment. A water displacement method was used to collect the biogas produced and subsequently measured by recording the volume of the displaced water in the calibrated container which was equal to the volume of biogas produced. Cumulative pressure range was 50.8271 N/m2-370.1771 N/m2. The cumulative biogas volumes of 0.0556 m3, 0.0643 m3, 0.0082 m3, 0.1136 m3, and 0.0437 m3 were produced from CD, CD + FDW, CD + FTW, CD + SD, and CD + FDW + FTW + SD, respectively. The result showed that the co-digestion of sawdust, food, and fruit wastes using cow dung could be a promising technology for sustainable biogas production if properly harnessed. Biogas is a clean energy which could alleviate greenhouse gas emission and also contribute to socioeconomic development and poverty eradication.