title: N2O and NO emissions from a partial nitrification sequencing batch reactor: exploring dynamics, sources and minimization mechanisms.
abstract: A sequencing batch reactor (SBR) was enriched with ammonia oxidizing bacteria (AOB) in order to treat synthetic reject wastewater (1 g NH4+ N/L). Partial nitrification was successfully achieved at a NH4+ -N to NO2- -N conversion rate of 98%. The emission dynamics of nitrous oxide (N2O) and nitric oxide (NO) were monitored during normal operation and under 3 different cycle configurations. An N2O peak was detected during the first 5 min of the cycle in all cases which corresponded to 60-80% of the total N2O emitted. When anoxic phases were introduced, N2O emissions were minimized but NO increased. Factors affecting the initial N2O peak were studied in a set of individual experiments. It was concluded that most of this N2O originated during settling due to biological reactions. Complete oxidation of NH4+ (or most likely hydroxylamine) as a result of sufficient aeration time can be a minimization strategy for N2O emissions in partial nitrification systems.
authors.affiliation: Catalan Institute for Water Research (ICRA), Emili Grahit Street, 101, H(2)O Building, Scientific and Technological Park of University of Girona, 17003 Girona, Spain. arodriguez@icra.cat
authors.forename: A
authors.initials: A
authors.lastname: Rodriguez-Caballero
authors.forename: M
authors.initials: M
authors.lastname: Pijuan
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D061249:Batch Cell Culture Techniques / Q000295:instrumentation*; D019149:Bioreactors; D009569:Nitric Oxide / Q000032:analysis*; D058465:Nitrification; D009609:Nitrous Oxide / Q000032:analysis*; D010084:Oxidation-Reduction; D000644:Quaternary Ammonium Compounds / Q000032:analysis
chemical_list: D000393:Air Pollutants; D000644:Quaternary Ammonium Compounds; D009569:Nitric Oxide; D009609:Nitrous Oxide