Simulation and experimental verification of nitrite-oxidizing bacteria inhibition by alternating aerobic/anoxic strategy.

Anaerobic ammonium oxidation (ANAMMOX) is a promising technology for sewage treatment. Alternating aerobic/anoxic conditions have been widely adopted to achieve partial nitrification (PN), so as to provide substrates for ANAMMOX. In this study, the feasibility of PN with the strategy of intermittent aeration was investigated under mainstream conditions. At a low dissolved oxygen (DO) concentration, the nitrogen conversion characteristic under different intermittent aeration modes was evaluated by mathematical simulation and experimental method with (1) ordinary activated sludge, (2) mixed sludge with anaerobic ammonia-oxidizing bacteria (AnAOB), and (3) PN sludge, as seed sludge. The existence of functional microorganisms, such as AnAOB and denitrifying bacteria, which can utilize nitrites, was the prerequisite for NOB activity inhibition in the alternating aerobic/anoxic condition. Therefore, low nitrite may be an important factor in NOB activity inhibition under alternating aerobic/anoxic conditions. This study demonstrated a key controlling factor for NOB activity inhibition with alternating aerobic/anoxic condition.