How is ammonia converted to nitrate in wastewater treatment?

Ammonia is converted to nitrate in wastewater treatment through a process known as nitrification. Nitrification is a crucial biological process involving the oxidation of ammonia by specific types of bacteria. This process occurs in two main steps: first, ammonia (NH3) is oxidized to nitrite (NO2-) by bacteria such as Nitrosomonas. Subsequently, nitrite is further oxidized to nitrate (NO3-) by another group of bacteria, primarily Nitrobacter.

This sequential conversion supports the overall nitrogen cycle in wastewater treatment, facilitating the removal of nitrogen compounds from the effluent and minimizing the environmental impact. The complete conversion to nitrate is critical because while ammonia is toxic to aquatic life, nitrate is less harmful, thus improving both the treatment process and the quality of discharged water. Other processes listed, such as denitrification, sedimentation, or chemical precipitation, serve different functions in wastewater treatment and are not directly responsible for ammonia's conversion to nitrate.