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

- Spent cow bedding digestion was compared in mesophilic and thermophilic conditions.
- Thermophilic temperature (TT) enhanced mainly easily-degradable matter digestion.
- Mesophilic and thermophilic reactors reached the same methane yield after 42 days.
- Higher biogas fluctuation at TT induced a decrease in the electricity production.
- The digestion of spent cow bedding at TT started easily without digestate addition.

Anaerobic digestion of spent cow bedding in batch leach-bed reactors (LBRs) 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, the anaerobic digestion in LBRs of spent cow bedding, a substrate rich in slowly-degradable compounds, was not improved in term of methane production considering the overall digestion time. 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.