Efficient Nitrification and Low-Level N2O Emission in a Weakly Acidic Bioreactor at Low Dissolved-Oxygen Levels Are Due to Comammox.

ABSTRACT: Nitrification is an essential process for nutrient removal from wastewater and an important emission source of nitrous oxide (N2O), which is a powerful greenhouse gas and a dominant ozone-depleting substance. In this study, nitrification and N2O emissions were tested in two weakly acidic (pH 6.3 to 6.8) reactors: one with dissolved oxygen (DO) at over 2.0 mg/liter and the other with DO at approximately 0.5 mg/liter. Efficient nitrification was achieved in both reactors. Compared to that in the high-DO reactor, N2O emission in the low-DO reactor decreased slightly, by 20%, and had insignificant correlation with the fluctuations of DO (P = 0.935) and nitrite (P = 0.713), indicating that N2O might not be produced mainly via nitrifier denitrification. Based on quantitative PCR (qPCR), quantita

SUBMITTER: Li D 

PROVIDER: S-EPMC8208134 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature