Which process is mainly responsible for the removal of nitrogen in wastewater treatment?

Denitrification is the process primarily responsible for the removal of nitrogen in wastewater treatment. It occurs in anaerobic conditions, where specific bacteria convert nitrates (NO3) and nitrites (NO2) into nitrogen gas (N2), which is then released into the atmosphere. This process is crucial in preventing nitrogen overload in aquatic systems, which can lead to problems such as eutrophication.

Nitrification, while related and important in the nitrogen cycle, primarily involves the oxidation of ammonia to nitrites and subsequently to nitrates, but it does not remove nitrogen from the system. Chemical precipitation and flocculation are processes that deal with the removal of solids and phosphates rather than nitrogen compounds. Therefore, denitrification stands out as the key biological process facilitating nitrogen removal from wastewater.