Nitrous oxide(N2O) is an important greenhouse gas and can destroy the ozone layer.More and more attentions have been paid to its effect on global changes.Biological nitrogen removal of domestic wastewater has been identified as an important anthropogenic source of N2O.Therefore it is important to study the production and control of N2O during biological nitrogen removal process.Review was made on the N2O production mechanisms,affecting factors and reduction strategies of biological nitrogen removal.N2O is u...