Identifying N2O formation and emissions from a full-scale partial nitritation reactor. (1st January 2016)

• Record Type: Journal Article
• Authors: Mampaey, Kris E.; De Kreuk, Merle K.; van Dongen, Udo G.J.M.; van Loosdrecht, Mark C.M.; Volcke, Eveline I.P.
• Is Part Of: Water research. Volume 88(2016)
• Page Start: 575
• Page End: 585
• Publication Date: 2016-01-01
• Subjects: Full-scale measurement -- Greenhouse gas -- kLa monitoring -- Nitritation -- Nitrous oxide -- Wastewater; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2015.10.047
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: In this study, N2 O 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 N2 O, O2, CO2 and NO. The overall N2 O emission was 3.7% of the incoming ammonium load. By fitting the N2 O emission to a theoretical gas stripping profile, the N2 O emissions could be assigned to aerobically formed N2 O and N2 O formed under anoxic conditions. This was further substantiated by liquid N2 O measurements. Under standard operation, 70% of the N2 O emission was attributed to anoxic N2 O formation. Dedicated experiments revealed that low dissolved oxygen concentrations (<1.0 g O 2 · m −3 ) and longer anoxic periods resulted in an increased N2 O emission. Minimising or avoiding anoxic conditions has the highest effect in lowering the N2 O emissions. As an additional result, the use of the off-gas N2 O concentration measurements to monitor the gas–liquid mass transfer rate coefficient ( k L a ) during dynamic reactor operation was demonstrated. Graphical abstract: Highlights: Identification of aerobically and anoxically formed N2 O. Majority of N2 O emission caused by anoxic N2 O formation. Dissolved N2 O measurements verified accumulation and subsequent stripping. Potential mitigation measures for N2 O emission reduction identified. Online gas–liquid mass transfer rate coefficient monitoring via off-gas measurements.