Effects of substrates on N(2)O emissions in an anaerobic ammonium oxidation (anammox) reactor

N(2)O emission in the anaerobic ammonium oxidation (anammox) process is of growing concern. In this study, effects of substrate concentrations on N(2)O emissions were investigated in an anammox reactor. Extremely high N(2)O emissions of 1.67 % were led by high NH(4)-N concentrations. Results showed that N(2)O emissions have a positive correlation with NH(4)-N concentrations in the anammox reactor. Reducing NH(4)-N concentrations by recycling pump resulted in decreasing N(2)O emissions. In addition, further studies were performed to identify a key biological process that is contributed to N(2)O emissions from the anammox reactor. Based on the results obtained, Nitrosomonas, which can oxidize ammonia to nitrite, was deemed as the main sources of N(2)O emissions.