title: Identifying N2O formation and emissions from a full-scale partial nitritation reactor.
abstract: In this study, N2O formation and emissions from a full-scale partial nitritation (SHARON) reactor were identified through a three-weeks monitoring campaign during which the off-gas was analysed for N2O, O2, CO2 and NO. The overall N2O emission was 3.7% of the incoming ammonium load. By fitting the N2O emission to a theoretical gas stripping profile, the N2O emissions could be assigned to aerobically formed N2O and N2O formed under anoxic conditions. This was further substantiated by liquid N2O measurements. Under standard operation, 70% of the N2O emission was attributed to anoxic N2O formation. Dedicated experiments revealed that low dissolved oxygen concentrations (<1.0 gO2·m(-3)) and longer anoxic periods resulted in an increased N2O emission. Minimising or avoiding anoxic conditions has the highest effect in lowering the N2O emissions. As an additional result, the use of the off-gas N2O concentration measurements to monitor the gas-liquid mass transfer rate coefficient (kLa) during dynamic reactor operation was demonstrated.
authors.affiliation: Department of Biosystems Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
authors.forename: Kris E
authors.initials: KE
authors.lastname: Mampaey
authors.affiliation: Waterschap Hollandse Delta, Handelsweg 100, 2980 GC Ridderkerk, The Netherlands.
authors.forename: Merle K
authors.initials: MK
authors.lastname: De Kreuk
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628BC Delft, The Netherlands.
authors.forename: Udo G J M
authors.initials: UGJM
authors.lastname: van Dongen
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628BC Delft, The Netherlands.
authors.forename: Mark C M
authors.initials: MCM
authors.lastname: van Loosdrecht
authors.affiliation: Department of Biosystems Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium. Electronic address: Eveline.Volcke@UGent.be.
authors.forename: Eveline I P
authors.initials: EIP
authors.lastname: Volcke
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D064751:Ammonium Compounds / Q000032:analysis; D019149:Bioreactors; D058465:Nitrification; D009609:Nitrous Oxide / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D000393:Air Pollutants; D064751:Ammonium Compounds; D009609:Nitrous Oxide
keywords: Full-scale measurement; Greenhouse gas; Nitritation; Nitrous oxide; Wastewater; k(L)a monitoring