title: Moderate temperature increase leads to disintegration of floating sludge and lower abundance of the filamentous bacterium Microthrix parvicella in anaerobic digesters.
abstract: Filamentous bacteria such as Microthrix parvicella can cause serious foaming and floating sludge problems in anaerobic digesters fed with sewage sludge. The sewage sludge and oil co-fermenting laboratory-scale biogas digesters in this study were fed with substrates from a foaming-prone full-scale biogas plant containing the filamentous bacterium M. parvicella. At 37 °C, in both pneumatically mixed digesters a highly viscous and approximately 3 cm thick floating sludge was observed. A gradual increase of the temperature from 37 °C to 56 °C led to a significant decrease in the floating sludge thickness, which correlated with a strong decrease in the abundance of M. parvicella in the digestate. Furthermore, the stepwise temperature increase allowed for an adaption of the microbial community and prevented process failure. The study indicates that already a moderate temperature increase from 37 °C to 41 °C might help to control the M. parvicella abundance in full-scale biogas plants.
authors.affiliation: GFZ German Research Centre for Geosciences, Section 4.5 Geomicrobiology, 14473 Potsdam, Germany. Electronic address: Tobias.Lienen@gfz-potsdam.de.
authors.forename: T
authors.initials: T
authors.lastname: Lienen
authors.affiliation: GFZ German Research Centre for Geosciences, Section 4.5 Geomicrobiology, 14473 Potsdam, Germany. Electronic address: Anne.Kleyboecker@gfz-potsdam.de.
authors.forename: A
authors.initials: A
authors.lastname: Kleyböcker
authors.affiliation: LabMET, Ghent University, Coupure Links 653, B-9000 Gent, Belgium. Electronic address: Willy.Verstraete@UGent.be.
authors.forename: W
authors.initials: W
authors.lastname: Verstraete
authors.affiliation: GFZ German Research Centre for Geosciences, Section 4.5 Geomicrobiology, 14473 Potsdam, Germany. Electronic address: Hilke.Wuerdemann@gfz-potsdam.de.
authors.forename: H
authors.initials: H
authors.lastname: Würdemann
mesh_terms: D039903:Actinobacteria / Q000254:growth & development*; D056804:Biofuels; D019149:Bioreactors; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D056804:Biofuels; D012722:Sewage
keywords: Biogas digester; DGGE; Floating sludge; Microthrix parvicella; Temperature increase; qPCR