Comparison of the mesophilic and thermophilic anaerobic digestion of spent cow bedding in leach-bed reactors

摘要

Anaerobic digestion of spent cow bedding in batch leach-bed reactors was compared in mesophilic and thermophilic conditions for the first time. Results show that the use of thermophilic conditions enhanced only the degradation kinetics of easily-degradable matter during the first days of the digestion, whereas similar methane yields (80% of the Biomethane Potential) were reached after 42 days at both temperatures. Therefore, thermophilic conditions did not improve the overall process performance when spent cow bedding, a substrate rich in slowly-degradable compounds, was digested. Moreover, the high initial biogas production rate in thermophilic reactors was found to significantly reduce the energetic performance of the cogeneration unit at industrial scale, leading to a 5.9 % decrease in the annual electricity production when compared to a mesophilic one.