Nitrite build-up effect on nitrous oxide emissions in a laboratory-scale anaerobic/aerobic/anoxic/aerobic sequencing batch reactor

Biological wastewater treatment processes with biological nitrogen removal are potential sources of nitrous oxide (N2O) emissions. It is important to expand knowledge on the controlling factors associated N2O production, in order propose emission mitigation strategies. This study therefore sought identify parameters that favor nitrite (NO2-) accumulation and its influence production an anaerobic/aerobic/anoxic/aerobic sequencing batch reactor removal. Even controlled dissolved oxygen concentrations oxidation reduction potential, first aerobic phase promoted only partial nitrification, resulting NO2- build-up (ranging from 29 57%) consequent generation. The was not fully consumed subsequent anoxic phase, leading even greater through denitrification. A direct relationship observed between these phases production. In N2O/NO2- ratio varied 0.5 8.5%, while one values ranged 8.3 22.7%. Higher noted during compared phase. As a result, highest fluxes occurred second ranging 706 2416 mg N m-2 h-1, as soon aeration triggered. Complete nitrification denitrification promotion this system proven be key factor avoid and, consequently,