DUGi

N2O and NO emissions from a partial nitrification sequencing batch reactor: Exploring dynamics, sources and minimization mechanisms

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@12576

A sequencing batch reactor (SBR) was enriched with ammonia oxidizing bacteria (AOB) in order to treat synthetic reject wastewater (1g 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 5min 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

This study was funded by the Spanish Government, Ministerio de Economı´a y Competitividad (project CTM 2011-27163) and the European Commission FP7-PEOPLE-2011-CIG 303946 project. M. Pijuan also acknowledges the Ramon y Cajal research fellowship (RYC-2009-04959) provided by the Spanish Government

Elsevier