Intermittent aeration in one-stage partial nitritation/anammox process

This study investigated the influence of different aeration strategies, characterized by the ratio (R) between non-aerated and aerated phase duration and dissolved oxygen concentration (DO), on one stage partial nitritation/anammox process performance and efficiency treating reject water. The activity of anammox bacteria, ammonium oxidizers, nitrite oxidizers and denitrifiers was determined by measuring specific anammox activity (SAA), oxygen uptake rate (OUR) and nitrate utilization rate (NUR). The results showed that with the same DO level during continuous aeration and intermittent aeration R = 1/3 (in one hour), nitrogen removal efficiencies were similar. This means that introduction of intermittent aeration with R = 1/3 can shorten the duration of aeration without any loss of process efficiency. Around 17-20% of the total decrease in ammonium and nitrate occurred in the non-aerated phase when intermittent aeration with R = 1/3 was applied. Moreover, introduction of non-aerated phases enhanced the activity of anammox bacteria and limited that of nitrite oxidizers.