Abstract
A 60m3 baffled anaerobic digester was installed in the ground and was operated with separated dairy manure slurry at a digester temperature of approximately 35°C. In the high loading operational mode, the maximum biogas production was 118.7m3/day, consisting of 56.5% methane gas with an average loading rate of 8.1kgVS/m3/day at an average ambient temperature of -7.1°C. A surplus biogas was used to fuel a 10kW engine generator to produce electricity and heat from condenser water was collected as hot water to maintain the digester slurry temperature. Fertilizer nutrients in the slurries are recovered after digestion process. Total Kjeldahl N added to the digester with the influents was completely recovered. Large increases in the concentrations of NH4-N during digestion were attributed to the mineralization of influent organic N. Coliform bacteria in the slurries declined to low or undetectable numbers after digestion process.
