Combined Benefits of Rapid Removal of Animal Manure and Their Anaerobic Digestion

This research quantifies the energy and emission benefits of coupling rapid evacuation of fresh manure from animal housing with anaerobic digestion, compared to conventional storage pathways. Field trials in pig and dairy farms showed that fresh pig slurry yields 10.7 Nm3 methane per fattening pig while aged slurry in pits loses 25–68% potential. Fresh dairy slurry provided approximately 57 Nm3 methane per cow per month, whereas strawy manure lost 1% of potential per day. Combining rapid removal and digestion cut greenhouse gas emissions by over 50%, but farm-scale digestion remains economically unviable under current investment costs. Anaerobic digestion also raised ammonia volatilization risks due to higher digestate pH.