Ammonia oxidation activity and potential of acclimatized activated sludge in a sequencing batch reactor at low temperature

In order to enhance the ammonia oxidation activity in low temperature wastewater treatment system, aerobic activated sludge collected from a local urban sewage treatment plant was acclimatized in a sequencing batch reactor (SBR) at temperature (15±1)°C by increasing the influent ammonia nitrogen (NH ₄ ⁺-N) concentration stage by stage. And then, the ammonia oxidation activity of the acclimatized activated sludge was evaluated by treating domestic sewage and high ammonia nitrogen wastewater. The results indicated that the inoculated activated sludge could obtain a better ammonia oxidation activity after acclimatized, with a specific NH ₄ ⁺-N removal rate of 54.26 g·kg ^-1·d ^-1 (as MLSS) and specific nitrite nitrogen (NO ₂ ^--N) producing rate of 29.07 g·kg ^-1·d ^-1 (as MLSS) at an initial NH ₄ ⁺-N of 46 mg·L ^-1. The NH ₄ ⁺-N removal was achieved more than 85% in the SBR when treating urban sewage with the initial NH ₄ ⁺-N of 47.19 mg·L ^-1. The acclimatized activated sludge also illustrated a better potential in treating high ammonia nitrogen wastewater. The specific NH ₄ ⁺-N removal rate could reach at 52.54 g·kg ^-1·d ^-1 (as MLSS) and 111.97 g·kg ^-1·d ^-1 (as MLSS) in the SBR when the initial NH ₄ ⁺-N concentration were 91.01 mg·L ^-1 and 163.37 mg·L ^-1, respectively.