title: Stable partial nitritation for low-strength wastewater at low temperature in an aerobic granular reactor.
abstract: Partial nitritation for a low-strength wastewater at low temperature was stably achieved in an aerobic granular reactor. A bench-scale granular sludge bioreactor was operated in continuous mode treating an influent of 70 mg N-NH4(+) L(-1) to mimic pretreated municipal nitrogenous wastewater and the temperature was progressively decreased from 30 to 12.5 °C. A suitable effluent nitrite to ammonium concentrations ratio to a subsequent anammox reactor was maintained stable during 300 days at 12.5 °C. The average applied nitrogen loading rate at 12.5 °C was 0.7 ± 0.3 g N L(-1) d(-1), with an effluent nitrate concentration of only 2.5 ± 0.7 mg N-NO3(-) L(-1). The biomass fraction of nitrite-oxidizing bacteria (NOB) in the granular sludge decreased from 19% to only 1% in 6 months of reactor operation at 12.5 °C. Nitrobacter spp. where found as the dominant NOB population, whereas Nitrospira spp. were not detected. Simulations indicated that: (i) NOB would only be effectively repressed when their oxygen half-saturation coefficient was higher than that of ammonia-oxidizing bacteria; and (ii) a lower specific growth rate of NOB was maintained at any point in the biofilm (even at 12.5 °C) due to the bulk ammonium concentration imposed through the control strategy.
authors.affiliation: GENOCOV Research Group, Department of Chemical Engineering, School of Engineering, Universitat Autònoma de Barcelona, Ed. Q - Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Isanta
authors.affiliation: GENOCOV Research Group, Department of Chemical Engineering, School of Engineering, Universitat Autònoma de Barcelona, Ed. Q - Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Clara
authors.initials: C
authors.lastname: Reino
authors.affiliation: GENOCOV Research Group, Department of Chemical Engineering, School of Engineering, Universitat Autònoma de Barcelona, Ed. Q - Campus UAB, 08193 Bellaterra, Barcelona, Spain. Electronic address: julian.carrera@uab.cat.
authors.forename: Julián
authors.initials: J
authors.lastname: Carrera
authors.affiliation: GENOCOV Research Group, Department of Chemical Engineering, School of Engineering, Universitat Autònoma de Barcelona, Ed. Q - Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: Pérez
mesh_terms: D000332:Aerobiosis; D064751:Ammonium Compounds / Q000032:analysis / Q000378:metabolism; D000693:Anaerobiosis; D001419:Bacteria / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D018613:Microscopy, Confocal; D008962:Models, Theoretical; D009566:Nitrates / Q000032:analysis* / Q000378:metabolism; D058465:Nitrification; D009573:Nitrites / Q000032:analysis* / Q000378:metabolism; D009576:Nitrobacter / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D015203:Reproducibility of Results; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods; D062065:Wastewater / Q000737:chemistry* / Q000382:microbiology*
chemical_list: D064751:Ammonium Compounds; D009566:Nitrates; D009573:Nitrites; D009584:Nitrogen; D010100:Oxygen; D012722:Sewage; D062065:Wastewater
keywords: Mainstream; Modeling; NOB repression; Partial nitritation