Abstract
A conventional system and a two-phase mesophilic anaerobic digestion system was studied at a digester temperature of 35°C using completely-mixed digesters. There were no significant differences between the two methods in the amount of biogas produced but a significant difference was recognized in the methane content (p<0.01). In the two-phase system, the methane content of the biogas produced remained high and constant. In the conventional system, material temperature had direct effects upon biogas production (p<0.05), but there was no significant difference between the two temperatures (5 and 35°C) in the methane content. The two-phase digestion system maintains its reduction of volatile solids, while a conventional system falls drastically when the loading rate (g of Volatile solids/liter per day) is larger than 10.
