Abstract

The efficiency of deammonification depends on the cooperation of ammonium oxidizing bacteria and archaea (AOB/AOA), anaerobic ammonium oxidizing bacteria (AnAOB) and the effective suppression of nitrite oxidizing bacteria (NOB) that compete with AnAOB for nitrite (NO2-N). One of the effective NOB suppression strategies is intermittent aeration. However, it is important to have a good understanding of the optimum dissolved oxygen (DO) value in the aeration period and optimize the non-aeration time used during the reaction phase. This study comprised the investigation of the effect of different DO set points (0.4, 0.7, 1.0 and 1.5 mg O2/L) under the same aeration length off/on (12/3 min). Moreover, three different intermittent aeration modes (9/3, 6/3, 3/3) under the same DO set point (0.7 mg O2/L) were more investigated. The experiment was conducted for 6 months (180 days) in a laboratory-scale sequencing batch reactor (SBR) with a working volume of 10 L. The results indicated that a high N removal efficiency was achieved 74% at the DO set point = 0.7 mg O2/L during aeration strategy off/on (6/3 min) due to the low nitrate production rate (NPR) 0.9 mg N/g VSS/h and high ammonium utilization rate (AUR) 13 mg N/g VSS/h (NPR/AUR = 0.06). Mathematical modeling results confirmed that the feasible DO set point 0.7 and intermittent aeration mode off/on (6/3 min) were especially suitable for the optimal balance between the NOB suppression and keeping high activities of AOB and anammox in the system.

Highlights

  • Published: 26 January 2022The deammonification process has received a special attention as a promising energyefficient technology for nitrogen removal

  • At the same time, which resulted in the nitrate production rate (NPR) value of 0.6 mg N/g VSS/h

  • (scenario 2), the ammonium utilization rate (AUR) increased to 6.6 mg N/g VSS/h, because the NH4 -N concentration decreased from 361 to 1.3 mg N/L in 23 h

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Summary

Introduction

Published: 26 January 2022The deammonification process has received a special attention as a promising energyefficient technology for nitrogen removal. Ammonium nitrogen (NH4 -N) is converted to nitrite nitrogen (NO2 -N) by ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) under aerobic conditions. The remaining NH4 -N (as an electron donor) and the produced NO2 -N (as an electron acceptor) are converted to nitrogen gas (N2 ) by anaerobic ammonia oxidizing bacteria (AnAOB) under anoxic conditions [1,2]. The efficiency of deammonification is dependent on the cooperation of AOB/AOA and AnAOB and the effective suppression of nitrite oxidizing bacteria (NOB) that compete with AnAOB for NO2 -N. This inhibition is a major challenge when applying this technology to sidestream or mainstream deammonification [3]

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