Water
·
2025
·Vol. 18
·期 1
·18
·
IF 3
Qiang Chen,Yi Ding,Zhicheng Xu,Haibin Zhou,Ruoyu Zhang,Jiao Chen,Yixin Lu,Wenlai Xu
Low reactivation efficiency of idle anaerobic ammonia oxidation (anammox) sludge hinders its reapplication. To address this issue, rape straw biochar (RSB) was added in the reactivation process of idle anammox sludge, and its effects on the nitrogen transformation and sludge characteristics were investigated, and the mechanism of RSB to enhance the reactivation performance was explored. Results indicated that adding 5 g/L RSB for 35 days successfully reactivated anammox sludge that had been idle for 270 days. The reactivation time was reduced by 34% compared to the control without RSB. During the stable operation period, the average TN removal efficiency reached 90.6%, and the sludge exhibited higher activity. After completion of reactivation, the specific surface area, total pore volume, and average pore diameter of RSB decreased by 59.4%, 66.9%, and 55.2%, respectively, compared with that before reactivation, and the carbon–oxygen functional groups also changed. RSB not only provided a habitat for the enriched growth of nitrogen transforming functional flora but also possessed the potential to supply sufficient electron donors and acceptors for the nitrogen transforming process, which promoted the synergistic removal of nitrate by denitrification, resulting in an effective enhancement of reactivation efficiency and nitrogen removal performance. The addition of RSB provides a novel strategy to enhance the reactivation efficiency of idle anammox sludge, which is of positive significance in promoting its efficient reuse and stable operation.
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iScience
·
2026
·Vol. 29
·期 8
·
IF 4.5
Jie Luo,Jiang Fan,Hong Liu,Xintao Lv,Zhiqiang Tang,Xiaoxia Wang,Fangjiao An,Yongzhi Chen
This study investigated eco-friendly immobilization carriers for AnAOB to enhance nitrogen removal from low-nitrogen domestic wastewater. Natural loofah sponge was evaluated as a novel biofilm carrier, with polyurethane sponge and polyethylene carrier as references. Microbial morphology, community structure, and nitrogen metabolism-related functional genes were systematically analyzed. Although the loofah sponge biofilm possessed the lowest abundances of Planctomycetota (39.38%) and Candidatus Brocadia (38.35%), it achieved over 90% TNRE and a maximum TNRR of 0.067 kgN/(m 3 ·d). The loofah sponge biofilm carrier also exhibited a denser, more uniform biofilm structure by SEM and higher relative abundances of key functional enzyme genes ( hdh , hzs , nirS , and nirK ) and ammonium transporter genes ( amt and FNT ) via metagenomic analysis. Long-term operation and typical cycle experiments validated its superior and stable anammox performance, providing a promising, sustainable, and easily applicable carrier strategy for practical anammox wastewater treatment systems.
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BIORESOURCE TECHNOLOGY
·
2026
·
IF 8.2
Xingcheng Zhao,Bo Wang,Fangxu Jia,Xu Zhang,Yawen Liu,Hong Yao
MWCNTs exhibit dose–dependent biphasic effects on anammox activity. • MWCNTs reprogram electron flow, not merely enhance conductivity. • EPS serves as a protective barrier, shielding microbes from MWCNT toxicity. • Low–dose MWCNTs induce mild oxidative stress as a metabolic cue, not toxic insult. • High–dose MWCNTs inhibit anammox activity via ROS accumulation and membrane damage. Integrating multi–walled carbon nanotubes (MWCNTs) into anaerobic ammonium oxidation (anammox) systems offers a promising nitrogen removal strategy, yet the balance between conductive stimulation and nanotoxicity remains poorly understood. This study elucidated the dose–dependent mechanisms of MWCNTs on anammox consortia. A distinct biphasic response was observed: low doses (optimal 30 mg·L −1 ) enhanced specific anammox activity by 18.82 ± 1.73% (p < 0.001), whereas high doses (≥ 100 mg·L −1 ) caused severe inhibition. Mechanistically, 30 mg·L −1 MWCNTs stimulated EPS to physically intercept nanoparticles while triggering an adaptive antioxidant response. Metatranscriptomic revealed that MWCNTs acted as “conductive bridges” to reprogram microbial electron flow, thereby selectively favoring AnAOB, promoting endogenous electron production and transfer, and ultimately enhancing the turnover of key terminal enzymes ( hzs , hdh ). Conversely, excessive exposure overwhelmed EPS and antioxidant defenses, causing reactive oxygen species accumulation and cellular disruption. Long–term operation confirmed sustained performance, expanding the AnAOB ecological niche (21.72 ± 9.62% increase) while suppressing competing denitrifiers. These findings provide a comprehensive molecular framework for precisely regulating nanomaterial dosing to optimize advanced wastewater treatment while mitigating ecological risks. Download: Download high-res image (227KB) Download: Download full-size image
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BIORESOURCE TECHNOLOGY
·
2023
·
IF 11.4
Xuejiao Qiao,Chenkun Fu,Yizhen Chen,Fang Fang,Yaoyu Zhang,Lingyun Ding,Kai Yang,Baozhu Pan,Nan Xu,Ke Yu,Huchun Tao,Lijuan Zhang
It has been widely reported that fluoroquinolones (FQs) can affect the anaerobic ammonium oxidization (anammox) microorganisms, which interferes with the performance of nitrogen removal from wastewater. However, the metabolic mechanism of anammox microorganisms responding to FQs has rarely been explored. In this study, it was found that 20 μg/L FQs promoted the nitrogen removal performance of anammox microorganisms in batch exposure assays, and 36–51% of FQs were removed simultaneously. Combined metabolomics and genome-resolved metagenomic analysis revealed up-regulated carbon fixation in anammox bacteria (AnAOB) , while purine and pyrimidine metabolism, protein generation and transmembrane transport were enhanced in AnAOB and symbiotic bacteria by 20 μg/L FQs. Consequently, hydrazine dehydrogenation, nitrite reduction, and ammonium assimilation were bolstered, improving the nitrogen removal efficiency of the anammox system. These results revealed the potential roles of specific microorganisms in response to emerging FQs and provided further information for practical application of anammox technology in wastewater treatment.
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BIOCHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 3.9
Han Zhang,Xiaojing Zhang,Bingbing Ma,Yongen Dong,Yaoyao Gong,Linhai He,Xiaohang Zhou
Anaerobic ammonia oxidation (Anammox) process was one of the most economical nitrogen removal technology, however, the slow growth rate and the shortage of sufficient seed sludge limit its application. In this study, Anammox was successfully established using residual sludge as seed sludge, and the variation in its nitrogen removal, stability, and microbial characteristics in response to the elevated ammonia and nitrite were explored. The sludge exhibited Anammox activity on day 34, and the system was successfully established on day 67, while the hzo gene expression increased from 1.1 * 10 4 to 9.4 * 10 5 copies/mL. The established Anammox system showed good resistance to the high nitrogen shock (200–1000 mg/L), and the relative abundance of Candidatus_Kuenenia notably increased. However, when the total nitrogen in influent reached 1200 mg/L, the nitrogen removal of the Anammox system was suppressed. And Candidatus_Kuenenia abundance significantly decreased while Arenimonas increased. Residual sludge could be adopted for establishing Anammox system, and the system could be used for efficiently treating wastewater with nitrogen lower than 1000 mg/L. The result in the present study has significance to the application of Anammox process and deeply save the economic cost of seed sludge since residual sludge was widely available.
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npj Clean Water
·
2021
·Vol. 4
·期 1
·1-11
·
IF 9.378
Ahmad Hafiz Adeel,Guo Beibei,Zhuang Xuming,Zhao Yiyi,Ahmad Shakeel,Lee Taeho,Zhu Jiegao,Dong Yuliang,Ni Shou-Qing
The prolonged start-up time and low total nitrogen removal of anammox hinder its full-scale application. Herein, application of nano-zerovalent iron and low strength magnetic field in sole and in combination to abbreviate the start-up period and long-term process stability of anammox was carried out. The reactor’s anammox start-up with the only magnetic field (R3) was 34 days, saving 43.3% time compared with the control. The increase of nitrogen removal efficiency over the control was 43.7% during the start-up period. However, the reactor with the coupled treatment of nano-zerovalent iron and magnetic field (R4) was more stable with higher nitrogen removal efficiency (80%) at high nitrogen loading (5.28 kg/m 3 /d). Anammox gene copy number in R4 was highest after 180 days of culture, followed by nano-zerovalent iron (R2) and R3 reactor. The functional genes of denitrifying bacteria (nirK and nirS) were also identified in all reactors with higher copy numbers in R2, followed by R4 and R3. Furthermore, high throughput analysis showed that the Thauera performing partial denitrification, Ignavibacterium performing dissimilatory nitrate reduction to ammonium or nitrite were also present in all reactors, more abundant in R4, confirming that the higher nitrogen removal efficiency in R4 was attributed to the synergistic relationship of other nitrogenous genera with anammox. The higher abundance of PD and DNRA in the reactor with the coupled treatment of nano-zero valent iron and magnetic field, achieved in this research, opens the opportunity of complete nitrogen removal via synergistic partial-denitrification, anammox, and DNRA (SPDAD) process.
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Environmental Technology & Innovation
·
2025
·
IF 7.1
Zhenxin Wang,Qilin Yu,Zhiqiang Zhao,Ruicheng Zhang,Hongbo Zhang,Yaobin Zhang
Anammox is limited in practical application due to the need to control the influent ratio of NO 2 - to NH 4 + . Fe(III) (hydr)oxides have been confirmed to serve as electron acceptors and induce a so-called Feammox to anaerobically oxidize ammonia in Anammox systems via extracellular electron transfer, which however is also restrained by the low activity of Fe(III) (hydr)oxides. Heme, a Fe-containing compound with high redox activity, was introduced into the Anammox system to improve NH 4 + oxidation in this study. A removal rate of 46.32 mg N/(L·d) was achieved for nitrogen through the addition of heme, which was 43.85% higher than the maximum Feammox efficiency in documents (32.20 mg N/(L·d)). Continuous experiments showed that the added heme participated in the intracellular and extracellular electron transfer of Anammox. The contribution of Feammox to nitrogen removal was affected by the influent NO 2 - -N/NH 4 + -N ratio. Under a high NO 2 - -N/NH 4 + -N ratio (1.25:1), the contribution of Feammox to NH 4 + -N removal was 8.29%. This ratio increased to 31.49% under a low NO 2 - -N/NH 4 + -N ratio (0.80). Besides increasing the nitrogen removal efficiency, heme addition may significantly lower the nitrite requirement in this biological process, leading to improved adaptability in its application.
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Journal of Water Process Engineering
·
2022
·
IF 7.34
Ying Wang,Haoyu Chen,Chao Chen,Zikun Zhang,Yin Xu,Guangjiao Chen,Yanlong Zhang
The anammox-HAP coupling process can simultaneously achieve high-efficiency nitrogen removal and phosphorus recovery from sewage. The composition and physical properties of the byproducts (aHAP) collected in the anammox-HAP process were analyzed. In addition, the application potential and mechanisms for Cd(II) adsorption by aHAP in wastewater were investigated. The results show that aHAP is mainly composed of hydroxyapatite and calcium carbonate , having granular structure with honeycombs and pores. The aHAP shows an adsorption capacity of 21.10–34.80 mg/g for Cd(II) removal, and the adsorption behavior is consistent with pseudo-second-order and intra-particle diffusion models, showing that the rate-limiting step is controlled by the chemical reaction of surface complexation, ion exchange, and precipitation. In addition, the remaining anammox biomass in aHAP can bind Cd(II). The aHAP also shows a pH buffer capacity when the initial pH ranges between 4.10 and 8.46, and the final pH can be stabilized in the range of 6.3 to 8.3, which is suitable for anammox reactions. Collectively, the anammox-HAP coupling process can not only be used to achieve high-efficiency nitrogen and phosphorus removal, but its aHAP byproduct shows good adsorption properties and pH buffering capacity, which meets the requirements of green chemistry and has high economic and environmental benefits.
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Environmental Science-Nano
·
2020
·Vol. 7
·期 6
·1681-1691
·
IF 7.683
Zheng-Zhe Zhang,Yu Zhang,Ya-Fei Cheng,Ren-Cun Jin
The risks of metallic nanoparticles (MNPs) in anammox have attracted increasing attention; however, how sulfidation, an important environmental transformation process, affects their toxicity potential is unclear. The chronic responses of anammox biomass to exposure to pristine and sulfurized MNPs were compared in this study. Exposure to 2.5 mg L−1 CuNPs and 2.5 mg L−1 ZnONPs resulted in an almost 99% decrease in nitrogen removal capacity within 55 days; however, 68% of the nitrogen removal capacity could be maintained with the aid of sulfidation. The inhibition on the transcription and enzyme activity of hydrazine dehydrogenase was attenuated by reducing the metal content of the anammox biomass, which induced higher specific anammox activity at the metabolic level and higher abundance of anammox bacteria at the community level over time. Therefore, these results highlight the need to consider environmental transformations of MNPs to accurately evaluate their potential environmental risks.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Sixin Zhang,Han Lv,Bin Cui,Dandan Zhou
Conventional Anammox systems using NO₂ − -N as an electron acceptor consistently face challenges of incomplete nitrogen removal due to NO₃ − -N production. Nitric oxide, a key intermediate in nitrogen cycling, presents a promising alternative electron acceptor for Anammox bacteria (AnAOB). To explore its feasibility, this study investigates the effects of NO on nitrogen transformations, microbial community dynamics and metabolic regulation within Anammox systems. Results revealed that NO elicited varied responses among nitrogen-transforming bacteria. Specifically, NO stimulation increased the relative abundance of AnAOB by 20.1 %–40.2 %, while suppressing nitrite-oxidizing bacteria (NOB) and denitrifiers (DNB). Consequently, the NO-dependent Anammox pathway contributed 15.4 % of total nitrogen removal and the NO₂ − -based pathway improved by 49.4 % according to isotope tracing. This shift was attributed to the ability of AnAOB to moderately uptake and efficiently utilize NO, maintaining intracellular NO levels 13.6 %–45.6 % lower than other bacteria, thereby avoiding oxidative stress and enhancing core metabolism. Additionally, NO facilitated ecological niche differentiation, strengthening interspecies cooperation mediated by metabolites, particularly between AnAOB and DNB ( Planctomycetia bacterium , Cyanobacteria bacterium CYA , etc.). Notably, NO supplementation increased NH 4 + -N removal by 1.5–1.9 times, with ΔNO₃ − -N/ΔNH₄ + -N decreasing by 45.2 %–54.8 %. These findings underscore the potential of NO-enhanced Anammox systems for advanced nitrogen removal in wastewater treatment.
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Water
·
2025
·Vol. 17
·期 17
·2611
·
IF 3
Keying Sun,Huining Zhang,Kefeng Zhang,Jianqing Ma,Zhengmin Pan,Shuting Zhang
The anaerobic ammonium oxidation (anammox) process offers potential for saline wastewater treatment but is hindered by salt inhibition. This study investigates the salt tolerance mechanisms of granular (R1), biofilm-carrier (R2), and floccular (R3) sludge in up-flow anaerobic sludge blanket (UASB) reactors under 0–20 g/L NaCl. Granular sludge outperformed other biomass types, maintaining >90% ammonia nitrogen (NH4+-N) removal at 20 g/L NaCl due to structural stability and extracellular polymeric substances (EPS) adaptation (shift from hydrophobic proteins to polysaccharides). Microbial analysis revealed a transition fromPlanctomycetes/Proteobacteriato salt-tolerantPseudomonadota, withCandidatus_KueneniareplacingCandidatus_Brocadiaas the dominant anaerobic ammonium oxidation bacteria (AnAOB) (reaching 14.5% abundance in R1). Genetic profiling demonstrated coordinated nitrogen metabolism: Hzs/Hdh inhibition (>85%) and NirBD/NrfAH activation (0.23%) elevatedNH4+-N, while NarGIV/NapA decline (1.10%→0.58%) increased nitrate nitrogen (NO3−-N). NxrB/NirSK maintained low nitrite nitrogen (NO2−-N), and GltBD upregulation (0.43%) enhanced osmoregulation. These findings underscore the superior resilience of granular sludge under high salinity, linked to microbial community shifts and metabolic adaptations. This study provides critical insights for optimizing anammox processes in saline environments, emphasizing the importance of biomass morphology and microbial ecology in mitigating salt inhibition.
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BIORESOURCE TECHNOLOGY
·
2024
·
IF 9.7
Li Zhang,Lixia Yang,Tingjun Dong,Jiachun Yang,Quanhao Dou,Shou-Qing Ni,Yongzhen Peng
The substantial discharge of ferroferric oxide nanoparticles (Fe 3 O 4 NPs) into sewage threatens the survival of functional microorganisms in wastewater treatment. This study elucidated responses of anaerobic ammonium oxidation (anammox) consortia to inhibition from high Fe 3 O 4 NPs concentration and recovery mechanisms. The nitrogen removal efficiency decreased by 20.3 % and recovered after 55 days under 1000 mg/L Fe 3 O 4 NPs concentration. Toxicity was attributed to reactive oxygen species (ROS) production. The excessive ROS damaged membrane integrity, nitrogen metabolism, and DNA synthesis, resulting in the inhibition of anammox bacteria activity. However, recovery mechanisms of anammox consortia activity were activated in response to 1000 mg/L Fe 3 O 4 NPs. The increase of heme oxygenase-1, thioredoxin, and nicotinamide adenine dinucleotide-quinone oxidoreductase genes alleviated oxidative stress. Furthermore, the activation of metabolic processes associated with membrane and DNA repair promoted recovery of anammox bacteria activity. This study provided new insights into NPs contamination and control strategies during anammox process.
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