title: Modeling nitrous oxide production during biological nitrogen removal via nitrification and denitrification: extensions to the general ASM models.
abstract: Nitrous oxide (N(2)O) can be formed during biological nitrogen (N) removal processes. In this work, a mathematical model is developed that describes N(2)O production and consumption during activated sludge nitrification and denitrification. The well-known ASM process models are extended to capture N(2)O dynamics during both nitrification and denitrification in biological N removal. Six additional processes and three additional reactants, all involved in known biochemical reactions, have been added. The validity and applicability of the model is demonstrated by comparing simulations with experimental data on N(2)O production from four different mixed culture nitrification and denitrification reactor study reports. Modeling results confirm that hydroxylamine oxidation by ammonium oxidizers (AOB) occurs 10 times slower when NO(2)(-) participates as final electron acceptor compared to the oxic pathway. Among the four denitrification steps, the last one (N(2)O reduction to N(2)) seems to be inhibited first when O(2) is present. Overall, N(2)O production can account for 0.1-25% of the consumed N in different nitrification and denitrification systems, which can be well simulated by the proposed model. In conclusion, we provide a modeling structure, which adequately captures N(2)O dynamics in autotrophic nitrification and heterotrophic denitrification driven biological N removal processes and which can form the basis for ongoing refinements.
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej building 113, 2800 Kongens Lyngby, Denmark.
authors.forename: Bing-Jie
authors.initials: BJ
authors.lastname: Ni
authors.forename: Maël
authors.initials: M
authors.lastname: Ruscalleda
authors.forename: Carles
authors.initials: C
authors.lastname: Pellicer-Nàcher
authors.forename: Barth F
authors.initials: BF
authors.lastname: Smets
mesh_terms: D000393:Air Pollutants / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism; D003198:Computer Simulation; D058440:Denitrification; D019811:Hydroxylamine / Q000378:metabolism; D008954:Models, Biological; D058465:Nitrification; D009584:Nitrogen / Q000378:metabolism; D009609:Nitrous Oxide / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D015203:Reproducibility of Results; D014865:Waste Disposal, Fluid; D018508:Water Purification
chemical_list: D000393:Air Pollutants; D000644:Quaternary Ammonium Compounds; D019811:Hydroxylamine; D009609:Nitrous Oxide; D009584:Nitrogen