Which type of bacteria is used to convert ammonia nitrogen in the activated sludge process?

The activated sludge process primarily relies on autotrophic bacteria to convert ammonia nitrogen into nitrates and eventually into nitrogen gas through the process of nitrification. Autotrophic bacteria utilize inorganic compounds as their source of energy and carbon, enabling them to oxidize ammonia to nitrite and further to nitrate. This group of bacteria includes nitrifying species such as Nitrosomonas and Nitrobacter, which play a vital role in maintaining the nitrogen cycle within wastewater treatment systems.

Heterotrophic bacteria, while essential in breaking down organic matter in the treatment process, do not specifically target ammonia nitrogen for conversion. Fermentative bacteria primarily function in anaerobic conditions to break down organic materials without using oxygen, which is not the primary focus of the activated sludge process. Pathogenic bacteria are harmful microorganisms that pose health risks and are not involved in the treatment process aimed at removing ammonia nitrogen. Thus, the use of autotrophic bacteria is crucial in effectively managing the nitrogen content in wastewater during the activated sludge process.