The article by Kampschreur et al. (2009) investigates the emission of nitrous oxide (N₂O) during wastewater treatment, a potent greenhouse gas. The study highlights that N₂O emissions can be significant, contributing to 26% of the total greenhouse gas footprint of the water chain. Key processes contributing to N₂O emissions include nitrification and denitrification, with nitrifying bacteria being a major source. The most important operational parameters influencing N₂O emissions are low dissolved oxygen concentrations during nitrification, increased nitrite concentrations in both nitrification and denitrification stages, and low COD/N ratios in the denitrification stage. The article also discusses the impact of rapidly changing process conditions, such as ammonia shock loads and oxygen limitation, on N₂O emissions. Additionally, it explores the role of internal storage compounds and pH levels in N₂O production. The authors recommend operational strategies to reduce N₂O emissions, such as ensuring sufficient oxygen supply during nitrification and managing COD/N ratios. They emphasize the need for further research to better understand and control N₂O emissions from wastewater treatment plants.The article by Kampschreur et al. (2009) investigates the emission of nitrous oxide (N₂O) during wastewater treatment, a potent greenhouse gas. The study highlights that N₂O emissions can be significant, contributing to 26% of the total greenhouse gas footprint of the water chain. Key processes contributing to N₂O emissions include nitrification and denitrification, with nitrifying bacteria being a major source. The most important operational parameters influencing N₂O emissions are low dissolved oxygen concentrations during nitrification, increased nitrite concentrations in both nitrification and denitrification stages, and low COD/N ratios in the denitrification stage. The article also discusses the impact of rapidly changing process conditions, such as ammonia shock loads and oxygen limitation, on N₂O emissions. Additionally, it explores the role of internal storage compounds and pH levels in N₂O production. The authors recommend operational strategies to reduce N₂O emissions, such as ensuring sufficient oxygen supply during nitrification and managing COD/N ratios. They emphasize the need for further research to better understand and control N₂O emissions from wastewater treatment plants.