Mesophilic versus thermophilic anaerobic digestion of cattle manure: methane productivity and microbial ecology.
In this study, productivity and physicochemical and microbiological (454 sequencing) parameters, as well as environmental criteria, were investigated in anaerobic reactors to contribute to the ongoing debate about the optimal temperature range for treating animal manure, and expand the general knowledge on the relation between microbiological and physicochemical process indicators. For this purpose, two reactor sizes were used (10 m(3) and 16 l), in which two temperature conditions (35°C and 50°C) were tested. In addition, the effect of the hydraulic retention time was evaluated (16 versus 20 days). Thermophilic anaerobic digestion showed higher organic matter degradation (especially fiber), higher pH and higher methane (CH₄) yield, as well as better percentage of ultimate CH₄ yield retrieved and lower residual CH₄ emission, when compared with mesophilic conditions. In addition, lower microbial diversity was found in the thermophilic reactors, especially for Bacteria, where a clear intensification towards Clostridia class members was evident. Independent of temperature, some similarities were found in digestates when comparing with animal manure, including low volatile fatty acids concentrations and a high fraction of Euryarchaeota in the total microbial community, in which members of Methanosarcinales dominated for both temperature conditions; these indicators could be considered a sign of process stability.
Department of Engineering, Aarhus University, Blichers Allé 20, DK 8830, Tjele, Denmark.
Veronica
V
Moset
Department of Animal Science, Aarhus University, Blichers Allé 20, DK 8830, Tjele, Denmark.
Morten
M
Poulsen
Department of Engineering, Aarhus University, Blichers Allé 20, DK 8830, Tjele, Denmark.|Faculty of Chemical Engineering, Universiti Teknologi Mara, 40450, Shah Alam, Malaysia.
Radziah
R
Wahid
Department of Animal Science, Aarhus University, Blichers Allé 20, DK 8830, Tjele, Denmark.
Ole
O
Højberg
Department of Engineering, Aarhus University, Blichers Allé 20, DK 8830, Tjele, Denmark.
Henrik Bjarne
HB
Møller
D000693:Anaerobiosis; D000818:Animals; D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology*; D058448:Biota; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D008372:Manure / Q000382:microbiology*; D008697:Methane / Q000378:metabolism*; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D013696:Temperature
D008372:Manure; D008697:Methane