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ANAMMOX Based Technology for Nitrogen Removal from Wastewater

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Wastewater Treatment and Reuse".

Deadline for manuscript submissions: 30 September 2025 | Viewed by 5877

Special Issue Editor


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Guest Editor
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China
Interests: wastewater; anammox; FNA; wetland; partial nitrification; quorum sensing; microbial interaction

Special Issue Information

Dear Colleagues,

Nitrogen pollution in wastewater has become a significant environmental challenge worldwide, leading to the eutrophication of water bodies and potential health risks. Traditional biological nitrogen removal processes, while effective, often require high energy input and have a large carbon footprint. In recent years, the Anaerobic Ammonium Oxidation (ANAMMOX) process has emerged as a promising and sustainable alternative for nitrogen removal from wastewater. ANAMMOX bacteria can convert ammonium directly into nitrogen gas using nitrite as an electron acceptor, bypassing the need for aeration and external carbon sources. This innovative biotechnology offers substantial benefits in terms of energy savings, reduced greenhouse gas emissions, and lower operational costs compared to conventional nitrification–denitrification processes.

This Special Issue focuses on the latest advancements in ANAMMOX biotechnology for nitrogen removal from wastewater. It aims to explore both the fundamental science and engineering applications of the ANAMMOX process, covering key topics such as partial nitrification, greenhouse gas emissions, quorum sensing, and bacterial community dynamics. This Special Issue will delve into how these factors influence the performance and stability of ANAMMOX systems and how to optimize the process for improved nitrogen removal efficiency. This Special Issue will also address the broader implications of ANAMMOX technology, including its role in achieving energy-efficient and environmentally sustainable wastewater treatment. It will explore how ANAMMOX contributes to reducing the carbon footprint of wastewater treatment plants and its potential for resource recovery.

This Special Issue invites the submission of original research papers or review papers covering the latest findings and progresses in this field. The below issues related to carbon neutrality and wastewater treatment are welcome:

  1. Advances in ANAMMOX reactor design and process configurations
  2. Integration of ANAMMOX with other wastewater treatment processes
  3. Microbial ecology and community dynamics in ANAMMOX systems
  4. Greenhouse gas emissions from ANAMMOX-based nitrogen removal processes
  5. Optimization strategies for enhancing ANAMMOX performance and stability
  6. Application of ANAMMOX in different types of wastewater

Dr. Cancan Jiang
Guest Editor

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Keywords

  • anammox
  • partial nitrification
  • greenhouse gas
  • quorum sensing
  • bacterial community

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Published Papers (6 papers)

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Research

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18 pages, 3581 KiB  
Article
Isolation and Characterization of Ammonia-Oxidizing Bacterium N.eA1: Insights into Nitrogen Conversion and N2O Emissions in Varied Environmental Conditions
by Yuhang Liu, Kai Li, Zhiyao Yan, Zhijun Ren, Xueying Li and Haobin Yang
Water 2025, 17(7), 1027; https://doi.org/10.3390/w17071027 - 31 Mar 2025
Viewed by 285
Abstract
While temperature, pH, DO, and ammonia nitrogen concentration are known to affect nitrous oxide (N2O) emissions from ammonia-oxidizing bacteria (AOB), the specific responses of individual AOB species to these environmental variables have yet to be fully elucidated. The present study reports [...] Read more.
While temperature, pH, DO, and ammonia nitrogen concentration are known to affect nitrous oxide (N2O) emissions from ammonia-oxidizing bacteria (AOB), the specific responses of individual AOB species to these environmental variables have yet to be fully elucidated. The present study reports the isolation and pure culture of a new AOB strain, designated as N.eA1, from a stable CANON bioreactor. The strain’s denitrification and N2O emission were systematically evaluated through a comprehensive analysis of growth kinetics, morphological characteristics, genetic composition, and nitrogen transformation under various environmental processes. Our results indicated that N.eA1 shares 95.33% sequence homology with Nitrosomonas europaea H1 AOB3, and exhibited higher nitrite (NO2-N) conversion efficiency. Morphological examination revealed white, semi-transparent spherical colonies. The bacterial growth kinetics included adaptation phase (0–12 h), exponential growth phase (12–36 h), stationary phase (36–72 h) and decline phase (after 72 h). Under optimal cultivation conditions (30 °C, DO concentration of 7.3 mg∙L−1, pH 8.0, and NH4+-N concentration of 260 mg∙L−1), the culture achieved a maximum growth rate of 0.0723 h−1, a maximum ammonia oxidation rate (AOR) of 10.74 mg∙(MLVSS∙h)−1, and a minimum doubling time of 9.59 h. The peak time of nitrogen conversion was earlier than that of N2O emission, with a maximum N2O-N conversion from NH4+-N of 1.039%. Full article
(This article belongs to the Special Issue ANAMMOX Based Technology for Nitrogen Removal from Wastewater)
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16 pages, 2870 KiB  
Article
Modified Fine Polyurethane Sponges with Polyvinyl Alcohol–Sodium Alginate Gel Coating as Bio-Carriers for Anammox Process
by Patcharaporn Phocharoen, Jarawee Kaewyai, Sineenat Thaiboonrod, Sanya Sirivitayaprakorn, Pongsak (Lek) Noophan and Chi-Wang Li
Water 2025, 17(5), 737; https://doi.org/10.3390/w17050737 - 3 Mar 2025
Viewed by 645
Abstract
This research investigates suitable bio-carriers for the anaerobic ammonium oxidation (anammox) process. This study evaluates the efficiency of the anammox process by assessing nitrogen removal efficiency using five different bio-carriers: fine and coarse polyurethane (PU) sponges, a melamine sponge, Scotch Brite, and a [...] Read more.
This research investigates suitable bio-carriers for the anaerobic ammonium oxidation (anammox) process. This study evaluates the efficiency of the anammox process by assessing nitrogen removal efficiency using five different bio-carriers: fine and coarse polyurethane (PU) sponges, a melamine sponge, Scotch Brite, and a loofah. Among the tested carriers, the reactor of the fine PU sponge media exhibited the highest nitrogen removal efficiency, achieving an 87% removal rate. This high efficiency was attributed to the substantial biomass containment, evidenced by a measured mixed liquor volatile suspended solids (MLVSS) amount of 1414 mg/L. Subsequently, the fine PU sponge, exhibiting the highest efficiency, was selected for further modification with a polyvinyl alcohol–sodium alginate (PVA-SA) gel coating to study the impact of methanol inhibition on nitrogen removal efficiency. An optimal modification condition was determined, utilizing concentrations of 8% PVA and 1.8% SA for the fine PU sponge media. The modified PU reactor exhibited the highest resistance to methanol inhibition, followed by the attached growth fine PU sponge reactor and suspended growth reactor. These findings suggest that there are benefits to using modified PU media for the anammox process in the field. Full article
(This article belongs to the Special Issue ANAMMOX Based Technology for Nitrogen Removal from Wastewater)
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13 pages, 1432 KiB  
Article
Significance of Influent C/N Ratios in Mainstream Anammox Process: Nitrogen Removal and Microbial Dynamics
by Yandong Yang, Shichong Liu, Lei Liu, Yanan Long, Chao Wang and Changqing Liu
Water 2025, 17(4), 562; https://doi.org/10.3390/w17040562 - 15 Feb 2025
Cited by 1 | Viewed by 506
Abstract
Achieving simultaneous anammox and denitrification is a feasible approach for enhancing nitrogen removal in mainstream anammox processes. Nevertheless, the optimal C/N range and microbial dynamics driving this process are still not fully understood. In this study, three mainstream anammox reactors were operated with [...] Read more.
Achieving simultaneous anammox and denitrification is a feasible approach for enhancing nitrogen removal in mainstream anammox processes. Nevertheless, the optimal C/N range and microbial dynamics driving this process are still not fully understood. In this study, three mainstream anammox reactors were operated with varying influent C/N ratios. The results demonstrated a remarkable nitrogen removal of 92.6% achieved by combining partial denitrification and anammox with the C/N ratio set at 1.0. However, the nitrogen removal efficiency decreased when the C/N ratio was either 0.5 or 2.0, causing the accumulation of nitrate and ammonium in the effluent, respectively. These results suggest a narrow optimal range of the influent C/N for mainstream anammox processes. Additionally, a transition in the predominant denitrifier population from Denitratisoma to Thauera was noted when the C/N ratio increased. The denitrifying phenotype of Thauera was significantly influenced by the C/N ratio. Thauera can effectively collaborate with anammox bacteria only at a suitable C/N ratio, where it partially reduces the nitrate generated in the anammox reaction. With a high influent C/N, Thauera primarily performed nitrite reduction, notably inhibiting anammox activity. The results of this study are valuable for the optimal design of the mainstream anammox process. Full article
(This article belongs to the Special Issue ANAMMOX Based Technology for Nitrogen Removal from Wastewater)
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14 pages, 5637 KiB  
Article
Rapid Start-Up of Anammox Process with a Stepwise Strategy: System Performance, Microbial Community Succession and Mechanism Exploration
by Sha Wang, Yangxin Yin, Yueyao Gao, Fang Li and Jian Zhou
Water 2024, 16(24), 3619; https://doi.org/10.3390/w16243619 - 16 Dec 2024
Viewed by 926
Abstract
Anammox has emerged as a primary alternative to conventional biological nitrogen removal because of its excellent nitrogen removal performance and minimal energy utilization. However, the slow growth and reproduction of anammox bacteria (AnAOB) leads to an overlong start-up period, which severely restricts the [...] Read more.
Anammox has emerged as a primary alternative to conventional biological nitrogen removal because of its excellent nitrogen removal performance and minimal energy utilization. However, the slow growth and reproduction of anammox bacteria (AnAOB) leads to an overlong start-up period, which severely restricts the full-scale promotion and application of anammox in wastewater treatment plants. Therefore, in this study, a sequencing batch biofilm reactor (SBBR) equipped with combined packing was used to investigate the rapid start-up of the anammox process. The result showed that the anammox reactor started successfully in only 75 days using a stepwise strategy, and the total nitrogen removal rate (TNRR) increased from 0.02 kg N m−3 d−1 on day 1 to 0.23 kg N m−3 d−1 on day 75. The primary AnAOB was Candidatus Kuenenia with a relative abundance of 37.20% at the end of the start-up of the anammox reactor. Denitrifying bacteria, nitrifying bacteria, and hydrolytic bacteria were also detected in the reactor. The synergistic interactions between AnAOB and these bacteria facilitated the efficient removal of pollutants. This study can offer a potential approach for the start-up of anammox in domestic wastewater treatment plants, which is conducive to achieving widespread application of anammox. Full article
(This article belongs to the Special Issue ANAMMOX Based Technology for Nitrogen Removal from Wastewater)
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12 pages, 1793 KiB  
Article
Lab-Scale Treatment of Anaerobic Co-Digestion Liquor from Kitchen Waste, Human Feces, and Municipal Sludge Using Partial Nitritation-Anammox Process
by Xiaolong Wang, Jialu Huang, Dongqian Li, Chao Liu and Dayong Tian
Water 2024, 16(16), 2321; https://doi.org/10.3390/w16162321 - 18 Aug 2024
Viewed by 1248
Abstract
Effective nitrogen removal from anaerobic co-digestion is a major challenge to achieving dual-carbon goals. This study explored the acclimatization process of a lab-scale two-stage partial nitritation and anammox process of a stepwise increase in the percentage of raw anaerobic co-digestion liquor from kitchen [...] Read more.
Effective nitrogen removal from anaerobic co-digestion is a major challenge to achieving dual-carbon goals. This study explored the acclimatization process of a lab-scale two-stage partial nitritation and anammox process of a stepwise increase in the percentage of raw anaerobic co-digestion liquor from kitchen waste, human feces, and municipal sludge in a venous industrial park in China, which has not been reported yet. Under limited dissolved oxygen (below 0.5 mg/L) and high ammonia levels (200–1500 mg/L), based on adjusting aeration rates, partial nitritation rapidly started up in 50 days. After acclimatization, partial nitritation still performed efficiently and stably, with the final total nitrogen loading rate (TNLR) of 1.24 ± 0.09 gN/L/d, nitrite accumulation rate of 99 ± 4%, and ratio of eff. nitrite/ammonia of 1.32 ± 0.13. In the anammox process, the final total nitrogen removal efficiency, total nitrogen removal rate, and TNLR reached 94 ± 5%, 1.27 ± 0.03 gN/L/d, and 1.36 ± 0.05 gN/L/d, respectively. Chemical oxygen demand (COD) was also reduced in both reactors, with COD removal rates of 0.7 gCOD/L/d in the partial nitritation and 0.4 gCOD/L/d in the anammox process. Overall, the PNA system demonstrated its feasibility in adapting to high ammonia, salinity, and iron levels, when treating anaerobic co-digestion liquor, particularly regarding resource recovery in venous industrial parks. Full article
(This article belongs to the Special Issue ANAMMOX Based Technology for Nitrogen Removal from Wastewater)
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Review

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17 pages, 1916 KiB  
Review
Regulating Denitrification in Constructed Wetlands: The Synergistic Role of Radial Oxygen Loss and Root Exudates
by Haishu Sun, Yuan Zhou and Cancan Jiang
Water 2024, 16(24), 3706; https://doi.org/10.3390/w16243706 - 22 Dec 2024
Cited by 1 | Viewed by 1783
Abstract
Constructed wetland (CW) is a critical ecological engineering for wastewater treatment and improvement of water quality. Nitrogen (N) removal is one of the vital functions of CWs during operation, and N treatment in CWs is mainly affected by aquatic plants and denitrification carried [...] Read more.
Constructed wetland (CW) is a critical ecological engineering for wastewater treatment and improvement of water quality. Nitrogen (N) removal is one of the vital functions of CWs during operation, and N treatment in CWs is mainly affected by aquatic plants and denitrification carried out by microbes. However, due to their low efficiency and instability in N removal, further applications of CWs are limited. The review provides a view of two basic characteristics of aquatic plants, radial oxygen loss (ROL) and root exudates, and their coupled effect on denitrification processes in CWs. First, the role of aquatic plants in denitrification is presented. The individual roles of ROL and root exudates in regulating denitrification, as well as their interaction in this process, have been discussed. Also, the limitation of conventional techniques to reveal interaction between the plant and the microbes has been highlighted. Further research on coupling regulatory mechanisms of ROL and root exudates may be conducted to develop an optimal wetland design and improve biological N removal. This review offers new insights and directions for improving N removal in CWs by utilizing the synergistic effects of plant ROL and root exudates. Full article
(This article belongs to the Special Issue ANAMMOX Based Technology for Nitrogen Removal from Wastewater)
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