DESIGN AND CONSTRUCTION OF ANAEROBIC DIGESTER SYSTEM FOR BIOGAS PRODUCTION FOR USE IN KADUNA POLYTECHNIC LABORATORIES

The research involves the design, fabrication and testing of a small-scale biogas system using galvanized and mild steel metal sheets and a motorized stirring mechanism. The work demonstrated that locally available materials can be used to build a robust and efficient system for waste-The research involves the design, fabrication and testing of a small-scale biogas system using galvanized and mild steel metal sheets and a motorized stirring mechanism. The work demonstrated that locally available materials can be used to build a robust and efficient system for waste-supply hose. The digester has a capacity of 0.943m3 tank with an operating pressure of 0.862MPa. The gas detention tank has a capacity of 0.30m3 with a bursting pressure of 269Mpa while the storage tank has a capacity of 0.008m3 with a bursting pressure of 535MPa. The storage tank operates at half the capacity of the detention tank while the detention tank operates at half the capacity of the digester tank. This shows that the system is not at any risks of failure due to gas pressure. Organic waste was used as the substrate for a 21 days anaerobic digestion period. Monitoring of temperature, pH and gas volume was conducted at 3 days interval. The operational results indicated a cumulative gas production of 1,013m3 with a pH level range of 6.4 – 7.1 at average temperature of 35oC. It also confirms that organic waste materials could serve as a suitable substrate for biogas production as they favour the growth of biogas producing microorganisms. The result also indicated that the highest volume of gas produced was under cow dung followed by sheep and lastly poultry. The result shows that the digester maintained mainly under mesophilic conditions can yield biogas consistently over 21 days retention period. The work provides a practical model for sustainable heat production in schools and laboratories using locally sourced available materials in Nigeria.