title: Challenges for simultaneous nitrification, denitrification, and phosphorus removal in microbial aggregates: mass transfer limitation and nitrous oxide production.
abstract: The microbial community composition and activity was investigated in aggregates from a lab-scale bioreactor, in which nitrification, denitrification and phosphorus removal occurred simultaneously. The biomass was highly enriched for polyphosphate accumulating organisms facilitating complete removal of phosphorus from the bulk liquid; however, some inorganic nitrogen still remained at the end of the reactor cycle. This was ascribed to incomplete coupling of nitrification and denitrification causing NO(3)(-) accumulation. After 2 h of aeration, denitrification was dependent on the activity of nitrifying bacteria facilitating the formation of anoxic zones in the aggregates; hence, denitrification could not occur without simultaneous nitrification towards the end of the reactor cycle. Nitrous oxide was identified as a product of denitrification, when based on stored PHA as carbon source. This observation is of critical importance to the outlook of applying PHA-driven denitrification in activated sludge processes.
authors.affiliation: Advanced Wastewater Management Centre, The University of Queensland, Building 64A, Research Road, Qld 4072, Australia. rikke.meyer@awmc.uq.edu.au
authors.forename: Rikke Louise
authors.initials: RL
authors.lastname: Meyer
authors.forename: Raymond Jianxiong
authors.initials: RJ
authors.lastname: Zeng
authors.forename: Valerio
authors.initials: V
authors.lastname: Giugliano
authors.forename: Linda Louise
authors.initials: LL
authors.lastname: Blackall
mesh_terms: D001420:Bacteria, Aerobic / Q000254:growth & development / Q000378:metabolism*; D001421:Bacteria, Anaerobic / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018441:Biofilms / Q000254:growth & development*; D018533:Biomass; D019149:Bioreactors; D015374:Biosensing Techniques / Q000379:methods; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D009609:Nitrous Oxide / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D009566:Nitrates; D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D010758:Phosphorus; D009609:Nitrous Oxide