Aeration strategies and temperature effects on the partial nitritation/anammox process for nitrogen removal: performance and bacterial community assessment.

The partial nitritation/anammox process (PN/A) could be a promising alternative for nitrogen removal from high-strength wastewater. There is, however, a lack of information about suitable aeration and temperature for PN/A in single-stage reactors for high-strength wastewater, such as food waste (FW) digestate treatment. To this end, a laboratory-scale (10 L) partial nitritation/anammox sequencing batch reactor was operated for more than 230 days under four different intermittent aeration strategies and temperature variations (35°C and ambient temperature - 26-29°C) to investigate the feasibility of nitrogen removal from real FW digestate. High ammonium (NH4+-N) and total nitrogen (TN) removal median efficiencies of 81 and 63%, respectively (corresponding to median NH4+-N and TN loads removed of 76 and 67 g.m-3.d-1), were achieved when the aeration strategy comprised by 7 min/14 min off and an airflow rate of 0.050 L.min-1.Lreactor-1 was applied. Nitrogen removal efficiencies were not affected by temperature variations in southeastern Brazil. COD, chloride and organic nitrogen (520, 239 and 102.8 mg.L-1, respectively) did not prevent PN/A. Changes of the bacterial community in response to aeration strategies were observed. Candidatus Brocadia dominated most of the time being more resistant to aeration and temperature changes than Candidatus Jettenia. This study demonstrated that optimizations of anoxic periods and airflow rate support PN/A with high nitrogen removal from FW digestate.