Therefore, main characteristic of
the process is the enrichment of ammonium-oxidizing bacteria
(AOB) and inhibition of nitrite-oxidizing bacteria (NOB) [1]. In
order to inhibit the activity of NOB, some operation conditions
have been used, including high temperature, appropriate pH, low
dissolved oxygen (DO) concentration, appropriate sludge retention
time (SRT), high substrate concentration, high free ammonia (FA)
concentration and aeration pattern