DEVELOPMENT OF A BIOGAS PLANT FROM COW DUNG, SWINE DUNG AND POULTRY DROPPING

Over dependent on crude oil in African countries call for the need for alternative source of renewable energy. A biogas digester of 56 liters capacity was locally designed, fabricated and tested at the workshop of Agricultural and Bio-Environmental Engineering Department of Rufus Giwa Polytechnic, Owo, Nigeria. The major components of the biogas include the digestion chamber comprising of stirrer which can be manually or electrically powered, a thermometer to measure the temperature variations of the digester and the hygrometer to measure the relative humidity of the environment. Investigations were made into the production of biogas from the mixture of three different substrates of cow dung, swine dung and poultry droppings. The proximate analysis showed that volatile solid, total solid and moisture content for the mixed substrates at the initial stage were; 64.7%, 83.5% and 13.5 % similarly at the digestion stage the volatile solid, total solid and moisture content were 54.1% 22.6% and 74.4%. As the decomposition proceeded, the pH value gradually increased up to 7.2 and 7.4 indicating the stability of organic matter. Moisture content on wet basis was 13.5%. These values latter increased to 74.4%. On the average, 15kg of mixed substrates with 25 liters of impure water produced biogas within 25 days of digestion. The gas produced from mixed substrates became flammable with blue flame after 16 days of production, indicating that the ratio of methane gas generated with three mixtures of fresh animal waste was higher than other gases produced. In conclusion, the mixed substrates produced faster than other substrates in mixture when compared to literatures. The cost of production was N 38,805.75, this price is considered been to be afforded by small and medium scale entrepreneurs.