Minimization of N2O Emission through Intermittent Aeration in a Sequencing Batch Reactor (SBR): Main Behavior and Mechanism

Abstract

To explore the main behavior and mechanism of minimizing nitrous oxide (N2O) emission through intermittent aeration during wastewater treatment, two lab-scale sequencing batch reactors operated at intermittently aerated mode (SBR1), and continuously aerated mode (SBR2) were established. Compared with SBR2, the intermittently aerated SBR1 reached not only a higher total nitrogen removal efficiency (averaged 93.5%) but also a lower N2O-emission factor (0.01–0.53% of influent ammonia), in which short-cut nitrification and denitrification were promoted. Moreover, less accumulation and consumption of polyhydroxyalkanoates, a potential endogenous carbon source promoting N2O emission, were observed in SBR1. Batch experiments revealed that nitrifier denitrification was the major pathway generating N2O while heterotrophic denitrification played as a sink of N2O, and SBR1 embraced a larger N2O-mitigating capability. Finally, quantitative polymerase chain reaction results suggested that the abundant complete ammonia oxidizer (comammox) elevated in the intermittently aerated environment played a potential role in avoiding N2O generation during wastewater treatment. This work provides an in-depth insight into the utilization of proper management of intermittent aeration to control N2O emission from wastewater treatment plants.

Nitrification kinetics, N2O emission, and energy use in intermittently aerated hybrid reactor under different organic loading rates

“…Liu et al ( 2021 ), investigating N 2 O emission in two activated sludge SBR reactors, observed lower N 2 O emission for the system operating with IA SBR1 (average 0.19%) than for that operating with continuous aeration (SBR2) (average 0.42%) (Table 7 ). The analysis of study results of Lo et al ( 2010 ) suggests that the amount of N 2 O emission also depends on the form of biomass in the reactor and DO concentration.…”

“…In the nitrification process, nitrous oxide is produced as a by-product of ammonia oxidation by AOB bacteria in two different ways: 1) incomplete oxidation of hydroxylamine (NH 2 OH) to nitrite and 2) reduction in nitrite as an acceptor of electrons to N 2 O (autotrophic denitrification conducted by AOB bacteria). N 2 O can also be a by-product of incomplete heterotrophic denitrification (Liu et al 2021 ).…”

Effect of the Aeration Strategy on NOB Suppression in Activated Sludge and Biofilm in a Hybrid Reactor with Nitrification/Denitrification

“…Roots et al [37] observed that Comammox bacteria constituted the majority of ammonia-oxidizing microorganisms in the intermittently aerated SBR reactor operating at DO concentrations in aeration phases at a level of 0.2-1 mg O 2 /L. Liu et al [39], conducting research in two SBR reactors differing in the applied aeration strategy, determined a considerably higher abundance of Comammox bacteria in the reactor operating with intermittent aeration (SBR1) with DO below 0.40 mg/L (averaged 0.14 mg/L) than in that with continuous aeration (SBR2) (range 0.29-0.65 mg/L, average 0.40 mg/L).…”

Adsorption of nitrate and nitrite from aqueous solution by magnetic Mg/Fe hydrotalcite

“…Several methods for removal of nitrate or nitrite from water have been applied, such as the reverse osmosis (Berkani et al 2019), catalytic reduction (Wcea et al;Han et al 2019), biological denitrification (Mulholland et al 2008;Liu et al 2021a), ion exchange and electrodialysis (Wiercik et al 2020;Zeng et al 2020). However, biological processes are easily affected by temperature, and the effluent needs further treatment, such as disinfection (Chen et al 2009;Zeng et al 2020).…”