Rapid achieving partial nitrification in domestic wastewater: Controlling aeration time to selectively enrich ammonium oxidizing bacteria (AOB) after simultaneously eliminating AOB and nitrite oxidizing bacteria (NOB).

This study developed a novel strategy for rapidly achieving partial nitrification (PN) without additional chemical agents, and infrastructure costs, only by controlling aeration time to selectively enrich ammonium oxidizing bacteria (AOB) after simultaneously eliminating AOB and nitrite oxidizing bacteria (NOB). Shorter aeration time and sludge retention time (10 days) were implemented to simultaneously eliminate AOB and NOB, the bioactivities drastically decreased to 13 and 0%, respectively. Subsequently, a gradually prolonged aeration time selectively enriched AOB and resulted in PN. The amoA abundances increased to 1.9 × 10 copies gVSS, whereas Nitrospira and Nitrobacter abundances remained stable (3.2 × 10 and 3.1 × 10 copies gVSS). A nitrite accumulation rate above 96% was achieved and maintained for 205 days over the entire temperature range (28.5-17.9 °C). The effluent contained 1.9 mg N L of ammonium, 25.3 mg N L of nitrite, and less than 1.0 mg N L of nitrate, facilitating mainstream wastewater anammox.