Optimization of AAO process for reduced N2O emissions and enhanced nitrogen removal in municipal wastewater treatment: Exploring carbon supplementation and DO control strategies

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL Water Research Pub Date : 2025-02-04 DOI:10.1016/j.watres.2025.123247

Zeming An, Qiong Zhang, Xinjie Gao, Baishuo Shao, Yongzhen Peng

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Abstract

The anaerobic/anoxic/oxic (AAO) process remains a common nutrient removal process in municipal wastewater treatment, yet research focusing on concurrent optimization of process performance and N₂O emissions reduction is scarce. This study aimed to investigate the mitigation of N₂O emissions and enhance nitrogen removal efficiency in an AAO system treating low C/N domestic wastewater by establishing a fully enclosed gas-collecting continuous flow reactor and implementing carbon supplementation and dissolved oxygen (DO) control strategies. The results indicated that carbon supplementation in the anoxic zone effectively reduced nitrate concentrations and mitigated the accumulation of dissolved N₂O below 0.1 mgN/L. The moderate DO control (1-2 mg/L) could ensure the nitrification efficiency while reducing the gaseous N₂O emission rate to 63.48 mgN/d, and decreasing the dissolved N₂O concentration in the effluent to below 0.01 mgN/L. Both too high and too low DO levels were detrimental to N₂O emission mitigation. The optimized AAO process achieved a significant reduction in the N₂O emission factor to 0.85% and an increase in nitrogen removal efficiency to 81.81%. Additionally, the enrichment of anammox bacteria, Candidatus brocadia (0.15%), positively contributed to the improvement in nitrogen removal efficiency. In conclusion, this study provides valuable insights into optimizing AAO process to mitigate N₂O emissions, enhance nitrogen removal, and lower carbon footprints associated with wastewater treatment.

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.