Unraveling rapid start-up and stable maintenance of partial nitrification in domestic wastewater under high dissolved oxygen

Partial nitrification (PN), is a promising nitrogen removal technology in wastewater treatment. Contrary to the dogma that low dissolved oxygen (DO) is more conducive to achieving PN, this study successfully established PN within 7 days under high DO conditions (> 6 mg/L). Ultra-stable PN was maintained over 143 days with an average nitrite accumulation ratio of 98 % treating real domestic wastewater. Kinetics indicated that the maximum activity difference increased to 40 folds between ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacterium (NOB), resulting in AOB prospering while NOB declined. High DO operation reshaped the nitrifier community with AOB genera relative abundance increased substantially (0.1 %-1.2 %), while the predominant NOB Nitrospira was below the detection limit. Batch test confirmed the reproducibility of this strategy to achieve PN using ordinary activated sludge. This study provides an update on developing a feasible approach for the rapid realization and stable maintenance of mainstream PN.