title: Ammonia oxidizing bacteria and archaea in horizontal flow biofilm reactors treating ammonia-contaminated air at 10 °C.
abstract: The objective of this study was to demonstrate the feasibility of novel, Horizontal Flow Biofilm Reactor (HFBR) technology for the treatment of ammonia (NH3)-contaminated airstreams. Three laboratory-scale HFBRs were used for remediation of an NH3-containing airstream at 10 °C during a 90-d trial to test the efficacy of low-temperature treatment. Average ammonia removal efficiencies of 99.7 % were achieved at maximum loading rates of 4.8 g NH3 m(3) h(-1). Biological nitrification of ammonia to nitrite (NO2 (-)) and nitrate (NO3 (-)) was mediated by nitrifying bacterial and archaeal biofilm populations. Ammonia-oxidising bacteria (AOB) were significantly more abundant than ammonia-oxidising archaea (AOA) vertically at each of seven sampling zones along the vertical HFBRs. Nitrosomonas and Nitrosospira, were the two most dominant bacterial genera detected in the HFBRs, while an uncultured archaeal clone dominated the AOA community. The bacterial community composition across the three HFBRs was highly conserved, although variations occurred between HFBR zones and were driven by physicochemical variables. The study demonstrates the feasibility of HFBRs for the treatment of ammonia-contaminated airstreams at low temperatures; identifies key nitrifying microorganisms driving the removal process; and provides insights for process optimisation and control. The findings are significant for industrial applications of gas oxidation technology in temperate climates.
authors.affiliation: School of Natural Sciences, National University of Ireland Galway, University Road, H91TK33, Galway, Ireland.|Ryan Institute for Environmental, Marine and Energy Research, National University of Ireland Galway, University Road, Galway, Ireland.
authors.forename: Seán
authors.initials: S
authors.lastname: Gerrity
authors.affiliation: Civil Engineering, College of Engineering & Informatics, National University of Ireland Galway, University Road, H91HX31, Galway, Ireland.|Ryan Institute for Environmental, Marine and Energy Research, National University of Ireland Galway, University Road, Galway, Ireland.
authors.forename: Eoghan
authors.initials: E
authors.lastname: Clifford
authors.affiliation: Civil Engineering, College of Engineering & Informatics, National University of Ireland Galway, University Road, H91HX31, Galway, Ireland.
authors.forename: Colm
authors.initials: C
authors.lastname: Kennelly
authors.affiliation: School of Natural Sciences, National University of Ireland Galway, University Road, H91TK33, Galway, Ireland. gavin.collins@nuigalway.ie.|Ryan Institute for Environmental, Marine and Energy Research, National University of Ireland Galway, University Road, Galway, Ireland. gavin.collins@nuigalway.ie.|School of Engineering, The University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, UK. gavin.collins@nuigalway.ie.
authors.forename: Gavin
authors.initials: G
authors.lastname: Collins
mesh_terms: D000388:Air / Q000032:analysis*; D000641:Ammonia / Q000302:isolation & purification* / Q000378:metabolism*; D001105:Archaea / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D018441:Biofilms; D019149:Bioreactors; D005240:Feasibility Studies; D009566:Nitrates / Q000378:metabolism; D058465:Nitrification; D009573:Nitrites / Q000378:metabolism; D010084:Oxidation-Reduction; D013696:Temperature
chemical_list: D009566:Nitrates; D009573:Nitrites; D000641:Ammonia
keywords: Ammonia oxidation; Ammonia oxidising archaea; Ammonia oxidising bacteria; Nitrification: low-temperature, HFBR (horizontal flow biofilm reactor)