Enhanced nitrogen removal via simultaneous nitrification-denitrification (SND) and Feammox in a magnetic zeolite modified intermittently aerated sequential biological reactor

Abstract

The practical application of the Feammox for nitrogen removal is challenging in the presence of high amounts of oxygen and organic carbon. This study presents a novel approach to address this issue which involves enhancing biological nitrogen removal in a magnetic zeolite modified intermittently aerated sequential biological reactor (MZeo-IASBR). The MZeo-IASBR demonstrated excellent performance, achieving 99.09% NH₄⁺-N and 89.12% TN removal efficiencies. The relative abundances of Proteobacteria, Planctomycetota, and Chloroflexi at the phylum level and Delftia and Pirellula at the genus level increased with the addition of NZ@Fe₃O₄, when compared to the microbial community analysis results of the IASBR with no addition of supplements and Zeo-IASBR with the addition of natural zeolite. The genera Acinetobacter and Bdellovibrio were mainly observed in the MZeo-IASBR system, and Acinetobacter may be related to the Feammox process. The combination of NZ@Fe₃O₄ and intermittent aeration under low oxygen levels promoted the aggregation of aerobic denitrifying bacteria and iron-reducing bacteria, which predominately removed nitrogen through the integration of simultaneous nitrification and denitrification (SND), Feammox, anammox, and NDFO processes. The MZeo-IASBR represents a promising strategy for advanced nitrogen removal in wastewater treatment, offering considerable supports for the practical application of Feammox processes.

Graphical abstract

Keywords

Magnetite / Zeolite / Intermittent aeration / Feammox / SND

Highlight

	● The addition of magnetic zeolite enhanced NH4+-N and TN removals.
	● A stable Feammox was achieved in MZeo-IASBR.
	● Aerobic denitrifying bacteria and iron-reducing bacteria were enriched.
	● Nitrogen was mainly removed through SND, Feammox, anammox, and NDFO processes.

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