Anaerobic Digestion Technology: The Energy, Environment and Health of Developing Nations

Anaerobic digestion process can be used as a tool for the production of energy, sanitation of the environment and prevention of communicable disease in developing countries such as Nigeria. This was demonstrated by using a 5m³ fixed dome digester for the production of Biogas for household use. The Cow dung was sourced from a local market in Bodija, Ibadan. The market is the largest among 39 markets in the city. There are 3,596 stalls which generate about 40 tonnes of organic waste every day. The wastes are currently dumped indiscriminately in about 346 sites, all over the market and environs which pollutes the environment. On daily basis some 300 cows are slaughtered. The dung is heaped up in the vicinity which is a breeding site for maggots. The water hyacinth was sourced from Awba Dam in University of Ibadan. The study was carried out under prevailing ambient between 29 and 34°C. A diameter of 2.4m was marked out for the digester. The actual diameter of the digester was 2.02 m. The remaining 0.4m was left out as the thickness of the digester which represents the thickness of the blocks that will be used (0.2m each). A total of 120 blocks were used in constructing the digester wall forming three layers. The inlet and outlet pipes were 2m each. The inlet and outlet pipes were positioned at an angle of 60º and 45º respectively. The dome is semi-circular in shape and was constructed at a height of 40cm. The digester was charged with two parts Cow dung (1000kg) and one part Water Hyacinth (500kg) mixed with 2,000 liters of water. After four weeks retention time, the pressure in the digester rose indicating biogas production. The amount of gas produced was 1.6m³/day. The gas was used for cooking purposes by the household. During the anaerobic digestion process, disease causing pathogens such as Salmonella and Shigella were reduced from the digestate.The result of this paper confirms the efficiency of anaerobic digestion technology as a tool for reducing disease causing pathogen, sanitizing the environment as well as producing energy if properly harnessed.