Quantifying, tracing and mitigating N2O production by ammonia-oxidizing archaea during mainstream nitrogen removal
Shengjun Li1, Yifeng Xu2, Mengwen Jia1
1Key Laboratory of Green Utilization of Critical Non-metallic Mineral Resources, Ministry of Education, Wuhan University of Technology, Wuhan 430070, China; Shenzhen Research Institute of Wuhan University of Technology, Shenzhen 518000 Guangdong, China.
Bioresource Technology
|December 3, 2025
Summary
Ammonia-oxidizing archaea produce significantly less nitrous oxide (N2O) than bacteria, with production decreasing at higher oxygen levels. Organic carbon mitigates nitrite inhibition, impacting N2O emissions in wastewater treatment.
Area of Science:
- Environmental microbiology
- Wastewater treatment technologies
- Greenhouse gas emissions
Background:
- Ammonia-oxidizing archaea (AOA) are crucial in nitrogen cycling but their role in wastewater treatment, particularly N2O production, is poorly understood.
- Wastewater systems are significant sources of N2O, a potent greenhouse gas, necessitating research into microbial contributors.
Purpose of the Study:
- To investigate ammonia oxidation and N2O production by a wastewater-derived AOA enrichment, focusing on the influence of oxygen and substrate availability.
- To precisely quantify N2O production by AOA, accounting for endogenous denitrification.
- To compare N2O production rates between AOA and ammonia-oxidizing bacteria (AOB).
Main Methods:
- Cultivation of a wastewater-derived AOA enrichment dominated by "Candidatus Nitrosocosmicus" using antibiotics.
- Controlled experiments varying oxygen levels (0.4-21%) and substrate availability (organic carbon, nitrite).
- Precise quantification of N2O production by correcting for denitrification, and measurement of biomass-specific N2O production rates.
Main Results:
- Biomass-specific N2O production by AOA was 90-97% lower than AOB across tested oxygen concentrations.
- N2O production in AOA showed a negative correlation with oxygen, linked to hybrid formation and abiotic hydroxylamine oxidation.
- Organic carbon alleviated nitrite inhibition in "Candidatus Nitrosocosmicus" by reducing nitrite, increasing N2O emission factors to 0.77-1.09% under specific conditions.
Conclusions:
- Wastewater-derived AOA contribute substantially less to N2O emissions compared to AOB.
- Oxygen availability is a key factor regulating N2O production by AOA.
- Understanding substrate interactions is vital for managing N2O emissions and optimizing nitrogen removal processes in wastewater treatment.
Keywords:
Candidatus NitrosocosmicusEmission reduction potentialEndogenous denitrificationNitrous oxideProduction pathwaysMore Related Videos
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