title: Empowering a mesophilic inoculum for thermophilic nitrification: Growth mode and temperature pattern as critical proliferation factors for archaeal ammonia oxidizers.
abstract: Cost-efficient biological treatment of warm nitrogenous wastewaters requires the development of thermophilic nitrogen removal processes. Only one thermophilic nitrifying bioreactor was described so far, achieving 200 mg N L(-1) d(-1) after more than 300 days of enrichment from compost samples. From the practical point of view in which existing plants would be upgraded, however, a more time-efficient development strategy based on mesophilic nitrifying sludge is preferred. This study evaluated the adaptive capacities of mesophilic nitrifying sludge for two linear temperature increase patterns (non-oscillating vs. oscillating), two different slopes (0.25 vs. 0.08 °C d(-1)) and two different reactor types (floc vs. biofilm growth). The oscillating temperature pattern (0.25 °C d(-1)) and the moving bed biofilm reactor (0.08 °C d(-1)) could not reach nitrification at temperatures higher than 46 °C. However, nitrification rates up to 800 mg N L(-1) d(-1) and 150 mg N g(-1) volatile suspended solids d(-1) were achieved at a temperature as high as 49 °C by imposing the slowest linear temperature increase to floccular sludge. Microbial community analysis revealed that this successful transition was related with a shift in ammonium oxidizing archaea dominating ammonia oxidizing bacteria, while for nitrite oxidation Nitrospira spp. was constantly more abundant than Nitrobacter spp.. This observation was accompanied with an increase in observed sludge yield and a shift in maximal optimum temperature, determined with ex-situ temperature sensitivity measurements, predicting an upcoming reactor failure at higher temperature. Overall, this study achieved nitrification at 49 °C within 150 days by gradual adaptation of mesophilic sludge, and showed that ex-situ temperature sensitivity screening can be used to monitor and steer the transition process.
authors: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium.
authors: Emilie N P
authors: EN
authors: Courtens
authors: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium.
authors: Tom
authors: T
authors: Vandekerckhove
authors: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium.
authors: Delphine
authors: D
authors: Prat
authors: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium.
authors: Ramiro
authors: R
authors: Vilchez-Vargas
authors: Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors: Marius
authors: M
authors: Vital
authors: Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors: Dietmar H
authors: DH
authors: Pieper
authors: Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), KU Leuven, Campus De Nayer, Fortsesteenweg 30A, 2860 Sint-Katelijne-Waver, Belgium.
authors: Ken
authors: K
authors: Meerbergen
authors: Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), KU Leuven, Campus De Nayer, Fortsesteenweg 30A, 2860 Sint-Katelijne-Waver, Belgium.
authors: Bart
authors: B
authors: Lievens
authors: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium.
authors: Nico
authors: N
authors: Boon
authors: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium; Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium. Electronic address: siegfried.vlaeminck@uantwerpen.be.
authors: Siegfried E
authors: SE
authors: Vlaeminck
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000254:growth & development* / Q000378:metabolism*; D001483:Base Sequence; D001673:Biodegradation, Environmental; D018441:Biofilms / Q000254:growth & development; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D005427:Flocculation; D008969:Molecular Sequence Data; D058465:Nitrification; D009573:Nitrites / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012722:Sewage / Q000382:microbiology; D013696:Temperature
chemical_list: D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D000641:Ammonia
keywords: Archaea; Nitrososphaera; Nitrospira; Thermophile