Water ResearchPub Date : 2025-03-25DOI: 10.1016/j.watres.2025.123550
Qingbai Tian , Xin Zhang , Jiale Chang , Dongdong Chen , Siyuan You , Xiaoming Peng , Baoyu Gao , Yanan Shang , Bo Wei , Qian Li , Zhen Hu , Yue Gao , Xing Xu
{"title":"Silico-oxygen bonding integrated with nano-size pore enrichment enables sustainable low-oxidant-consumption Fenton-like chemistry","authors":"Qingbai Tian , Xin Zhang , Jiale Chang , Dongdong Chen , Siyuan You , Xiaoming Peng , Baoyu Gao , Yanan Shang , Bo Wei , Qian Li , Zhen Hu , Yue Gao , Xing Xu","doi":"10.1016/j.watres.2025.123550","DOIUrl":"10.1016/j.watres.2025.123550","url":null,"abstract":"<div><div>Key bottlenecks of the persulfate-based advanced oxidation processes (AOPs) are the high dosage of persulfate and the secondary pollution of sulfate ion. In this work, a sustainable strategy involving the transformation of diatomite into a water purification catalyst consisting of nano-size pore enrichment and silico-oxygen bonding (Si/C@BD) was proposed. Results indicated that the pollutants with electron-donating groups can be quickly degraded by the Si/C@BD via amplified electron transfer process (ETP) under very low peroxymonosulfate (PMS) usage. Such “low-oxidant-consumption” Fenton-like chemistry can be also applied to other catalytic systems derived from a series of silicon-based materials. In addition, a pilot-scale device (54 L) based on ETP pathway was constructed, which provided a universal strategy to prevent direct contact of treated wastewater with oxidation additives, thereby solving the bottleneck of secondary pollution caused by sulfate dissolution associated with PMS oxidation systems. In addition, the Si/C@BD/PMS system exhibited the superior environmental significance and feasibility based on the quantitative analysis via the life cycle assessment (LCA). This work will be a significant contribution to the persulfate-based Fenton-like chemistry, emphasizing the low-persulfate-consumption and free-secondary-pollution characteristics with significant application value.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"281 ","pages":"Article 123550"},"PeriodicalIF":11.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143695654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water ResearchPub Date : 2025-03-25DOI: 10.1016/j.watres.2025.123555
Dong Li, Yuling Zhang, Xiaosi Su, Jili Wang, Ningfei Li
{"title":"Seasonal freeze-thaw significantly alters the distinct aquifers solute transport, microbial community assembly patterns, and molecular ecological networks in the hyporheic zone","authors":"Dong Li, Yuling Zhang, Xiaosi Su, Jili Wang, Ningfei Li","doi":"10.1016/j.watres.2025.123555","DOIUrl":"https://doi.org/10.1016/j.watres.2025.123555","url":null,"abstract":"Elucidating the diversity patterns and assembly mechanisms of microbial communities is crucial for comprehending ecological processes and assessing biogeochemical cycles in the hyporheic zones of cold regions. The spatial and temporal diversity patterns and mechanisms governing these microbial communities are not yet well understood. Our study revealed that microbial richness decreased rapidly during the initial freezing period. However, it began to increase during the deep freezing period due to the role of cold-resistant microorganisms. Meanwhile, the diversity of microorganisms showed a trend that was in line with the lake water- groundwater changes in temperature. <em>Achromobacter</em> and <em>Crenothrix</em> have been designated as biomarkers for the initial freezing period and deep freezing period, respectively. In these phases, factors such as dispersal limitation (26.8%-47.6%) and drift (15.1%-45.2%), along with other random factors, are the primary drivers of bacterial community assembly. Physical properties (pH, T, DO, EC, Eh) have been identified as the predominant factors (r=0.75, p<0.01) affecting the progression of community succession in hyporheic systems throughout the freeze-thaw cycles. Conversely, nutrient properties (r=0.36, p<0.01) and the presence of heavy metals (r=0.18, p<0.01) play lesser roles, influencing community composition according to partial least squares path modeling. Our insights significantly enhance the understanding of microbial communities in the HZ of frigid areas and carry important consequences for the stewardship and safeguarding of lacustrine ecosystems.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"24 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143703259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water ResearchPub Date : 2025-03-25DOI: 10.1016/j.watres.2025.123556
Lin Gao , Ze Yuan , Xiaoteng Mao , Ting Ma
{"title":"Salinity levels, trends and drivers of surface water salinization across China's river basins","authors":"Lin Gao , Ze Yuan , Xiaoteng Mao , Ting Ma","doi":"10.1016/j.watres.2025.123556","DOIUrl":"10.1016/j.watres.2025.123556","url":null,"abstract":"<div><div>The salinization of freshwater resources constitutes an increasingly global challenge, exacerbated by climate change and human activities. Despite its growing significance, comprehensive assessments of salinity dynamics and the roles of natural and anthropogenic factors remain scarce. This study investigates surface water salinity levels and their long-term (2003–2022) and seasonal trends across 1356 sampling sites in ten major Chinese river basins. Our results reveal that >20 % of the sites exhibit relatively high long-term average salinity levels compared to the irrigation water threshold, primary in arid or semi-arid regions experiencing intensified human activities. Nearly 20 % of low-salinity sites exhibit significant trends towards increased salinity, primarily in humid region. Southern basins, such as the Pearl River and Yangtze River, generally have relatively low salinity but demonstrate upward trends, whereas northern basins, like the Yellow River and Huai River, experience moderate to high salinity levels with more rapid increases. Winter salinity levels and their rate of increase surpass those of other seasons. Anthropogenic drivers, particularly population density and agricultural water use, emerge as key contributors to rising salinity, in conjunction with hydroclimatic variables. Furthermore, seasonal salinity trends underscore the critical role of agricultural water use during summer and autumn months. These findings emphasize the necessity to address the compounded pressures of climate variability and human activities, which are increasingly threatening surface water quality through rising salinity and extreme weather events.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"281 ","pages":"Article 123556"},"PeriodicalIF":11.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143703263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water ResearchPub Date : 2025-03-25DOI: 10.1016/j.watres.2025.123553
Kenia Barrantes-Jiménez, Franck Lejzerowicz, Tam Tran, Melany Calderón-Osorno, Luis Rivera-Montero, César Rodríguez-Sánchez, Odd-Gunnar Wikmark, Alexander Eiler, Hans-Peter Grossart, María Arias-Andrés, Keilor Rojas-Jiménez
{"title":"Anthropogenic imprint on riverine plasmidome diversity and proliferation of antibiotic resistance genes following pollution and urbanization","authors":"Kenia Barrantes-Jiménez, Franck Lejzerowicz, Tam Tran, Melany Calderón-Osorno, Luis Rivera-Montero, César Rodríguez-Sánchez, Odd-Gunnar Wikmark, Alexander Eiler, Hans-Peter Grossart, María Arias-Andrés, Keilor Rojas-Jiménez","doi":"10.1016/j.watres.2025.123553","DOIUrl":"https://doi.org/10.1016/j.watres.2025.123553","url":null,"abstract":"Plasmids are key determinants in microbial ecology and evolution, facilitating the dissemination of adaptive traits and antibiotic resistance genes (ARGs). Although the molecular mechanisms governing plasmid replication, maintenance, and transfer have been extensively studied, the specific impacts of urbanization-induced pollution on plasmid ecology, diversity, and associated ARGs in tropical regions remain underexplored. This study investigates these dynamics in a tropical aquatic ecosystem, providing novel insights into how pollution shapes plasmid composition and function. In contrast to the observed decrease in chromosomal diversity, we demonstrate that pollution associated with urbanization increases the diversity and taxonomic composition of plasmids within a bacterial community (plasmidome). We analyzed eighteen water and sediment metagenomes, capturing a gradient of pollution and ARG contamination along a tropical urban river. Plasmid and chromosomal diversity profiles were found to be anti-correlated. Plasmid species enrichment along the pollution gradient led to significant compositional differences in water samples, where differentially abundant species suggest plasmid maintenance within specific taxonomic classes. Additionally, the diversity and abundance of ARGs related to the plasmidome increased concomitantly with the intensity of fecal and chemical pollution. These findings highlight the critical need for targeted plasmidome studies to better understand plasmids' environmental spread, as their dynamics are independent of chromosomal patterns. This research is crucial for understanding the consequences of bacterial evolution, particularly in the context of environmental and public health.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"21 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143703257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water ResearchPub Date : 2025-03-25DOI: 10.1016/j.watres.2025.123551
Pengfei Hu, Mark van Loosdrecht, Ji-Dong Gu, Yuchun Yang
{"title":"The core anammox redox reaction system of 12 anammox bacterial genera and their evolution and application implications","authors":"Pengfei Hu, Mark van Loosdrecht, Ji-Dong Gu, Yuchun Yang","doi":"10.1016/j.watres.2025.123551","DOIUrl":"https://doi.org/10.1016/j.watres.2025.123551","url":null,"abstract":"Anaerobic ammonium-oxidation (anammox) is a typical redox reaction driven by membrane electron transformation. However, the electron transfer mechanism of the core redox reaction and its evolutionary origins are still not thoroughly identified. In this study, a preliminary analysis was conducted for such interaction based on the 64 anammox bacterial genomes representing 12 genera available currently. The results suggested that enzymes involved in anammox reaction share the similar catalytic and electron transfer modes in different lineages, while the electron-carrying proteins shuttled between membrane and soluble enzymes are very different. A comparatively simple electronic shuttle protein system was encoded in the early-branching groundwater lineages Candidatus (Ca.) Avalokitesvara and <em>Ca</em>. Tripitaka, which was replaced by a sophisticated electron carrier scheme in the late-branching marine and terrestrial groups within family <em>Ca</em>. Brocadiaceae. Remarkably, the increasing availability of nitrite after Great Oxidation Event (GOE) potentially drove the adaptive evolution of the core redox systems by successively recruiting the nitrite reductase (NIR) for nitrite balance, a stable complex of two small cytochrome <em>c</em> proteins (NaxL and NaxS homologues) for electron transfer to HZS, as well as optimizing the structure of nitrite oxidoreductase gamma (NxrC) for electron conservation. In particular, a tubule-inducing nitrite oxidoreductase subunit (NxrT homologue) was further formed for electron transformation after the Neoproterozoic Oxygenation Event (NOE). Finally, based on two full-scale anammox-based wastewater treatment systems (WWTPs), we identified core gene transcriptional activities affecting the abundance of the family Ca. Brocadiaceae and their association with environmental factors. Overall, our study not only provides key information for understanding the dynamic patterns and evolutionary mechanisms of the anammox reactions and the associated electron transfers in conjunction with major geological events, but also provides new insights for future enrichment and effective applications.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"30 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143703261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"History of carbon supply shapes the metabolic response of photogranules to light shifts","authors":"Oriane Della-Negra , Anaïs Séguéla , Camille Guilmineau , Roselyne Gautier , Cécile Canlet , Rémi Servien , Kim Milferstedt , Jérôme Hamelin","doi":"10.1016/j.watres.2025.123557","DOIUrl":"10.1016/j.watres.2025.123557","url":null,"abstract":"<div><div>Oxygenic photogranules mainly composed of cyanobacteria and heterotrophic bacteria, have gained attention for their ability to treat wastewater (removal of C, N, and P) without external aeration. Currently, the metabolic dynamics of photogranules to varying nutrient and light conditions in wastewater treatment systems remains poorly studied. However, understanding how quickly the photogranule metabolism changes, and whether this change is temporary or permanent is important for the optimal use of photogranules. Here, an NMR-based metabolomics approach was applied to investigate the temporal dynamics of photogranule metabolism in the presence or absence of acetate and with or without light.</div><div>Our findings revealed that under carbon-limited conditions, photogranules relied on alternative carbon sources, such as N-acetylneuraminate (a constituent of EPS) and amino acids like hypotaurine and L-alanine. This adaptation affected key metabolic pathways, including glycolysis, taurine and hypotaurine metabolism, and the tricarboxylic acid cycle. When acetate was provided, both heterotrophic and phototrophic activities were maintained. Notably, the history of carbon supply influenced how photogranules responded to light shifts. Metabolic indicators showed that the lag in carbon addition altered fatty acid metabolism and carbon fixation, leading to shifts in amino acid concentrations and distinct metabolic profiles when the light was turned off. Thus, NMR metabolomics identified metabolic changes, induced by contrasting carbon conditions, lasting for several hours, and significantly affecting the photogranule response to light fluctuations. These results suggest that the history of carbon supplementation may shape metabolic responses of photogranules to other environmental changes or stressors.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"281 ","pages":"Article 123557"},"PeriodicalIF":11.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143703264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water ResearchPub Date : 2025-03-25DOI: 10.1016/j.watres.2025.123502
Baoqing Deng, Qi Zheng, Nuo Chen
{"title":"Comment on “Modeling the settling and resuspension of microplastics in rivers: Effect of particle properties and flow conditions”, published by Akdogan and Guven [Water Research 260 (2024) 121900]","authors":"Baoqing Deng, Qi Zheng, Nuo Chen","doi":"10.1016/j.watres.2025.123502","DOIUrl":"10.1016/j.watres.2025.123502","url":null,"abstract":"<div><div>The present comment reveals the misuse of the mixing length theory in the settling velocity and the drawback in the mass conservation equations of microplastics for the compartments of water column, water-sediment interface and sediment.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"280 ","pages":"Article 123502"},"PeriodicalIF":11.4,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143703262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water ResearchPub Date : 2025-03-24DOI: 10.1016/j.watres.2025.123545
Yongyong Zhang , Jian Wu , Yang Gao , Gangsheng Wang , Jing Wang , Xuefa Wen
{"title":"Estimation of organic carbon source composition and riverine outflow using an integrated watershed hydrological–carbon modelling approach","authors":"Yongyong Zhang , Jian Wu , Yang Gao , Gangsheng Wang , Jing Wang , Xuefa Wen","doi":"10.1016/j.watres.2025.123545","DOIUrl":"10.1016/j.watres.2025.123545","url":null,"abstract":"<div><div>Carbon source apportionment and outflow estimation are the primary scientific considerations for reducing carbon output from watershed ecosystems to ocean. However, carbon loss and transportation mechanisms from soil to river system driven by watershed hydrological cycle, remain unclear. Our study developed a process–based watershed organic carbon model that integrates soil biogeochemical processes, overland loss, riverine metabolism and transportation driven by hydrological processes, and estimates the sources, outflows and their spatial distributions. The proposed model was validated using long-term field observations of runoff and labile particulate, dissolved, and total organic carbon (LOC, DOC and TOC) loads across the Xiangxi Watershed in China. The biases within ±0.25 were for all runoff simulations and for 71.4 % (30/42) of carbon load simulations, and both Nash–Sutcliffe efficiency and correlation coefficient were over 0.60 for runoff simulation and for 83.3 % (35/42) of carbon load simulations. Annual average TOC load flowing into rivers was 11.3 ton<sup>.</sup>km<sup>-2.</sup>yr<sup>-1</sup>, with resistant particulate organic carbon (ROC) as the main form, accounting for 88.7 % of the TOC load. Atmospheric deposition was the primary TOC source with a contribution of 87.9 %, followed by soil loss. Annual average riverine TOC outflow was 3.8 ton<sup>.</sup>yr<sup>-1</sup>, with LOC and DOC accounting for 57.5 % and 40.0 %, respectively. This indicates that a majority of ROC decomposed into DOC and LOC via riverine metabolism and sedimentation. Our study provides insights into integration mechanisms of watershed hydrological and carbon cycles, and contributes to strategies for controlling water and carbon losses to strengthen terrestrial carbon sequestration.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"280 ","pages":"Article 123545"},"PeriodicalIF":11.4,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water ResearchPub Date : 2025-03-24DOI: 10.1016/j.watres.2025.123547
Ali Beryani , Kelsey Flanagan , Shujie You , Fredrik Forsberg , Maria Viklander , Godecke-Tobias Blecken
{"title":"Critical field evaluations of biochar-amended stormwater biofilters for PFAS and other organic micropollutant removals","authors":"Ali Beryani , Kelsey Flanagan , Shujie You , Fredrik Forsberg , Maria Viklander , Godecke-Tobias Blecken","doi":"10.1016/j.watres.2025.123547","DOIUrl":"10.1016/j.watres.2025.123547","url":null,"abstract":"<div><div>Biochar is often promoted as an ideal amendment for stormwater biofilters; however, its effectiveness has rarely been tested under field conditions. This study evaluates the impact of biochar addition on the removal of organic micropollutants (OMPs) in field-scale biofilters operating under real-world conditions for the first time. The research comprised four vegetated biofilter facilities (3 − 5 years old), two without and two with 2.1 wt<em>.</em> % (10 vol<em>.</em> %) biochar amendment. Stormwater and filter material samples from various locations after four years of operation were analyzed for a wide range of common and emerging OMPs found in urban runoff. Unlike hydrophobic OMPs (hydrocarbons, polychlorinated biphenyls, and di(2-ethylhexyl) phthalate), the investigated biofilters demonstrated low, or inconsistent, removal of hydrophilic and slow-adsorbing OMPs like bisphenol A, monobutyltin, and per-fluoroalkyl substances (PFASs). Although the physiochemical properties of biochar were well-adapted to pollutant removal, biochar amendment did not significantly improve OMP removal when compared with the status quo. This can be attributed to several field conditions and suboptimal design interfering with the biochar's sorption capacity, namely, the large particle size (D<sub>50</sub> ∼4 mm) and low quantity of biochar, high levels of competing agents (i.e., dissolved oxygen carbon (DOC) and cations), co-contaminants in stormwater, limited contact time, biochar pore blockage (e.g., by DOC molecules and sediments/minerals), diminished biochar surface porosity, and sometimes increased removal uncertainty due to low influent concentrations. Our findings demonstrated the complexities associated with applying biochar for stormwater treatment. Further research on biochar-specific biofilter designs is needed to optimize the sorption potential of this material under field conditions.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"281 ","pages":"Article 123547"},"PeriodicalIF":11.4,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143695691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Molecular identification of heterotrophic nitrification and aerobic denitrification bacteria: From methods development to application demonstration","authors":"Rui-chun Yang, You-wei Cui, Zhen-ying Li, Ming-teng Li, Liu-xu Jiang, Ya-nan Mi, Yuan Sui, Hui-kai Liang","doi":"10.1016/j.watres.2025.123542","DOIUrl":"10.1016/j.watres.2025.123542","url":null,"abstract":"<div><div>Although heterotrophic nitrification and aerobic denitrification (HN-AD) bacteria, a novel functional group involved in nitrogen conversion, have been isolated and characterized, the lack of specific molecular markers for identification severely limits the study of their role in geochemical cycling and the contribution in ecosystems. Here, a set of molecular markers was developed for the rapid identification of HN-AD bacteria, via delving into the genomics and transcriptomics of a HN-AD isolate (<em>Pseudomonas aeruginosa</em> SNDPR-01). Among the nine candidate genes that were significantly expressed during heterotrophic nitrification, three were involved in the conversion of hydroxylamine to nitrite, a characteristic process of HN-AD. The universality and stability of the identification methods based on the gene primer set were validated using pure HN-AD strains, mixed cultures of pure HN-AD strains, and activated sludge from laboratory-scale and real wastewater treatment plants. In all cases, the amplification outcome was positively correlated with the function and population of HN-AD bacteria, demonstrating its validity as a molecular marker. This study supports the paradigm of heterotrophic nitrification from hydroxylamine to nitrite. As an effective tool for the identification of classic HN-AD bacteria, this study lays the groundwork for research on environmental ecology and biotechnological application of HN-AD bacteria.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"280 ","pages":"Article 123542"},"PeriodicalIF":11.4,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}