Nitrous oxide (N₂O) is a potent greenhouse gas that can be emitted during wastewater treatment, contributing significantly to the greenhouse gas footprint. This study reviews the factors influencing N₂O emissions in wastewater treatment plants (WWTPs) and identifies key operational parameters that lead to N₂O emissions. N₂O can be emitted during nitrification and denitrification processes, with nitrification being primarily responsible for N₂O emissions due to oxygen limitation, while denitrification can also contribute. The study highlights that N₂O emissions are influenced by factors such as low dissolved oxygen concentrations, increased nitrite levels, and low COD/N ratios. The research also identifies the need for further studies to better understand and control N₂O emissions from WWTPs. The study emphasizes the importance of monitoring and controlling operational parameters to minimize N₂O emissions, as even small amounts of N₂O can have a significant impact on the greenhouse effect. The findings suggest that N₂O emissions are mainly from activated sludge units in WWTPs, and that effective management of these units is crucial for reducing N₂O emissions. The study also notes that the emission of N₂O can be affected by rapidly changing process conditions, and that adaptation of microbial populations can lead to reduced emissions. Overall, the study underscores the need for further research to develop strategies for reducing N₂O emissions from wastewater treatment processes.Nitrous oxide (N₂O) is a potent greenhouse gas that can be emitted during wastewater treatment, contributing significantly to the greenhouse gas footprint. This study reviews the factors influencing N₂O emissions in wastewater treatment plants (WWTPs) and identifies key operational parameters that lead to N₂O emissions. N₂O can be emitted during nitrification and denitrification processes, with nitrification being primarily responsible for N₂O emissions due to oxygen limitation, while denitrification can also contribute. The study highlights that N₂O emissions are influenced by factors such as low dissolved oxygen concentrations, increased nitrite levels, and low COD/N ratios. The research also identifies the need for further studies to better understand and control N₂O emissions from WWTPs. The study emphasizes the importance of monitoring and controlling operational parameters to minimize N₂O emissions, as even small amounts of N₂O can have a significant impact on the greenhouse effect. The findings suggest that N₂O emissions are mainly from activated sludge units in WWTPs, and that effective management of these units is crucial for reducing N₂O emissions. The study also notes that the emission of N₂O can be affected by rapidly changing process conditions, and that adaptation of microbial populations can lead to reduced emissions. Overall, the study underscores the need for further research to develop strategies for reducing N₂O emissions from wastewater treatment processes.