Keywords: retention time, yield, Nigeria, operational parameters, floating drum biogas plant, rural areas, gas production rate, quality, burner output pressure, cattle slurry
Determination of appropriate operational parameters of a floating–drum biogas plant for rural Nigeria
This paper determined the appropriate operational parameters of a floating–drum biogas plant that give the highest gas production rate (m³/h), best gas quality (% methane fraction) and required output pressure (mbar) for burners. The operational parameters were retention time and weight on the floating drum of the plant. The retention times of 15, 20, 25, and 30 days, and weights of 50, 100, 150 and 200 kg were investigated. A 3 m³ floating–drum biogas plant was used for the study. The plant was fed with cattle slurry of 11% total solids concentration (waste: water = 1:2) and loaded every fifth day of each of the retention time investigated. The carbon to nitrogen ratio, total solids concentration and pH of the slurry were determined. The results obtained showed that gas quality (% CH4 fraction) increased from 32% to 75% as the retention time increased from 15 days to 30 days. The retention time of 30 days and storage weight of 150 kg gave the highest gas production rate of 0.68 m³/h. The minimum weight of 115 kg which gave the minimum pressure of 7 mbar is recommended for use on the plant.