Effect of cow dung variety on biogas production

Biogas is a renewable, alternative and sustainable form of energy from the action of bacteria when waste vegetable matter, organic waste and some industrial waste are fermented in the absence of oxygen. This study was conducted to find the effect of cow dung variety on biogas generation. Some samples of fresh cow dung (2 Kg for each breed of cow) of cows which were not exposed to treatment with anti-biotics for some weeks, were collected from Sobere Farms and mixed with water in ratio of 1:1 volume and the mixture was loaded into a bio-reactor to ferment. The Hydraulic Retention Time (HRT) was 9 to 14 days. The reduction in retention time was achieved by adding human excreta and urine into the digester to increase micro-organism and pathogenic activities. The biogas obtained after 11 days was gathered and analyzed in a 250-Gas Chromatograph and Integrator. The results showed the percentages and calculated energies (calorific values) of biogas from the cow dung of four (4) selected varieties of cows, namely, Holstein Friesian, Simmental, White Fulani and Jersey, which were fed with concentrates in equal proportions and at the same time for some weeks. The Holstein cow has methane (CH4),(84.916%) and 196.199 cal/m3 of energy, Jersey cow (69.233%) and 159.963 cal/m3 of energy, (60.459%) and 149.235 cal/m3 of energy for Simmental cow and White Fulani cow has (85.331%) with 197.157 cal/m3 of energy respectively. The results indicate that the White Fulani cow has the higher quantity of combustion energy than the other breeds of cows.   Key words: Effect, White Fulani, Holstein, Jersey, Simmental, biogas, percentages, cow dung.