Design, Construction and Testing of a Biogas Reactor for Production of Biogas using Cassava Peel and Cow Dung as Biomass

Cassava peel and cow dung have constituted to global warming worldwide because it constitutes heaps of agro-wastes that contributes immensely to greenhouse gas (GHG) emission. Their contributions to environmental hazards are enormous due to high production of methane gas while degrading. A methane gas can be used for domestic and industrial application if produced and refined in a biogas reactor. A biogas reactor of capacity 0.29 m3 was designed and constructed to produce biogas (methane) using dried cassava peel and cow dung biomass as substrate. The simplicity of the design aids easy loading and unloading, air tightness and operated at mesophilic temperature of 32°C and pH of 6.80. The machine consists of agitator for mixing the biomass to prevent the formation of scum, inlet pipes, valves, gas outlet, and stand, crank and pressure gauge. All components were made of galvanized steel except valves outlet and inlet pipes which was made of galvanized aluminum pipe. The criteria considered in the design of the biogas reactor included air tightness of the whole unit, mesophilic temperature, pH, nature of substrate, and substrate retention period. The biogas reactor was tested with 24 kg of dried cassava peel co-mixed with 48 kg of pasty cow dung in ratio 1:2. Daily gas yield was determined; gas pressure in the biogas reactor was measured by pressure gauge, while the ambient temperature was measured using hand held mercury-in-glass thermometer. Results show that biogas was produced after 24 days retention period at average substrate temperature and pH of 32°C and 6.80 respectively. The reactor was designed to accommodate 0.145m3 of substrate equivalent to half of the reactor volume. The reactor has a total production cost of ₦31,360 with all materials being available locally.