Biogas Production from Blends of Cassava Waste Water and Cow Dung under Changing Meteorological Parameters

Abstract

Biogas production from cassava waste water (CWW) blended with cow dung (CD) in different proportions was studied in five treatments under changing meteorological conditions. The treatment cases A—100% CWW; B: 100% CD; C: 90% CWW + 10% CD; D: 70% CWW + 30% CD; and E: 50% CWW + 50% CD—were digested under anaerobic conditions in model batch, metallic biodigesters of 32.0 litres for 30 days within ambient conditions. The digester performances indicated that 100% CD system flamed on the 6^th day, 70% CWW + 30% CD system flamed on the 16^th day, 50% CWW + 50% CD system flamed on the 17^th day while 100% CWW system and 90% CWW + 10% CD systems didn’t flame at all. The cumulative gas yield from the five treatments was different: the 100% CWW had cumulative gas yield of 12.7 litres/24 kg mass of slurry; 100% CD had cumulative gas yield of 41.5 litres/24 kg mass of slurry; 90% CWW +10% CD had cumulative gas yield of 13.85 litres/24 kg mass of slurry; 70% CWW+30% CD had cumulative gas yield of 14.85 litres/24 kg mass of slurry while 50% CWW + 50% CD had cumulative gas yield of 7.55 litres/24 kg mass of slurry during the 30 days retention period. 100% CD had 79.9995% methane; 70% CWW + 30% CD produced 79.9995% methane while 50% CWW + 50% CD produced 88.499% methane. Daily biogas yields were also modelled as functions of meteorological parameters and results recorded.