Methane emission during on-site pre-storage of animal manure prior to anaerobic digestion at biogas plant: Effect of storage temperature and addition of food waste

This study investigated the temperature dependency of CH4 emission from pre-storage of animal manure prior to anaerobic digestion at 15, 20, 25 and 30 degrees C using lab-scale anaerobic digesters. The manure was added and removed daily to simulate the pre-storage process at biogas plants. CH4 emission accounted for 1-46% of total CH4 potential from pig manure (PM) and 1-2% of that from cattle manure (CM) at the investigated temperatures, with significant increases above 25 degrees C. Addition of food waste (FW) reduced the CH4 emission when storage temperature was 20 degrees C or lower for PM and 25 degrees C or lower for CM due to volatile fatty acid accumulation and lower pH (< 5.5) but emissions increased with higher storage temperatures.