CEST2025

The deammonification process is an energy-efficient solution for nitrogen removal in wastewater treatment, relying on the synergy between ammonia-oxidizing bacteria (AOB) and anammox bacteria while suppressing nitrite-oxidizing bacteria (NOB). This study aimed to enhance the process by identifying aeration strategies that suppress NOB while maintaining anammox bacteria's high activity. The research was carried out across four experimental series. These series varied in aeration strategies, including continuous and intermittent aeration, with different R ratios and dissolved oxygen (DO) concentrations. Following the implementation of these aeration strategies in the reactor, batch tests, and next-generation sequencing were conducted. The results demonstrated that switching from continuous aeration to intermittent aeration (R=1/2, DO= 1.5 mg O₂/L) significantly suppressed NOB activity from 17.6 mg N/gVSS·h to 8.2 mg N/gVSS·h. Simultaneously, these conditions maintained high anammox activity (52.1 mg N/gVSS·h), highlighting the process's robustness under low oxygen concentrations. Increasing DO concentration to 2.5 mg O₂/L caused an increase in AOB (57,8 mg N/gVSS·h) and anammox (65,2 mg N/gVSS·h) activity together with a decrease in NOB activity (5,9 mg N/gVSS·h). However, further decreases in the duration of aerated phases (R=1) led to a decline in anammox activity. Under continuous aeration, Nitrospira abundance was the highest, correlating with elevated NOB activity. The highest abundance of Nitrosomonas was observed with the intermittent aeration strategy (R = 1/2, DO = 2.5 mg O₂/L), aligning with higher AOB activity. Interestingly, the abundance of anammox bacteria (Candidatus Brocadia) remained comparable across all experimental stages, despite notable differences in their activity levels. This discrepancy suggests that microbial abundance alone may not fully reflect metabolic activity, emphasizing the importance of combining NGS with batch tests for a comprehensive evaluation of microbial processes. These findings also highlight the critical role of aeration strategy and DO control in balancing microbial communities and optimizing deammonification performance.