Partial nitritation/anammox applied to real anaerobically pretreated domestic sewage under subtropical climate: aeration strategies and nitrogen cycle bacteria.

The combination of sewage anaerobic treatment and partial nitritation/anammox process (PN/A) can make wastewater treatment plants energetically self-sufficient. However, PN/A application has been a challenge in low-nitrogen wastewaters and it is little explored in anaerobically pretreated domestic sewage, as well as aeration strategies and the PN/A feasibility at ambient temperature. This study investigated PN/A in a sequential batch reactor (SBR) treating real anaerobically pretreated domestic sewage. After the startup, SBR was fed with real wastewater and operated at 35°C and at ambient temperature (20-31°C) without total nitrogen (TN) removal decrease (71 ± 8 and 75 ± 6%, respectively). The median ammonium and TN removals were 68 ± 21 and 59 ± 9%, respectively with 7 min on/14 min off strategy, which represents 12.3 ± 4.2 mg L ^-1 N-NH ₄ ⁺ effluent, which is lower than Brazilian discharge limits. The qPCR results showed anammox abundance in the range of 10 ⁸ -10 ⁹ n° copies gVSS ^-1 . Thus, results were very promising and showed the feasibility of the PN/A process for treating real anaerobically pretreated domestic sewage at ambient temperature.