Water Research最新文献

{"title":"Revealing microbial pathways of N2O production in agricultural ditches","authors":"Xiaoqian He, Zhifeng Yan, Shanyun Wang, Sophie A. Comer-Warner, Xia Zhu-Barker","doi":"10.1016/j.watres.2025.124732","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124732","url":null,"abstract":"Agricultural ditches are recognized as hotspots of nitrous oxide (N₂O) emissions, yet the contributions of different microbial pathways under varying environments remain largely unknown. In this study, we quantified N₂O production from four microbial pathways (nitrifier nitrification, nitrifier denitrification, nitrification-coupled denitrification, and heterotrophic denitrification) across a gradient of ditch types (from large to small: main, branch, collector, and field ditches). Using a dual isotope tracing technique (¹⁵N-¹⁸O), we distinguished pathway-specific N₂O production under different oxygen and organic carbon (C) conditions. Nitrifier denitrification dominated N₂O production in the three largest ditch types (contributing 68.7-83.6%), while heterotrophic denitrification accounted for 85.4% of the total N₂O production in the field ditch. As organic C increased, heterotrophic denitrification-derived N₂O production increased significantly, whereas the contribution of nitrifier denitrification of N₂O production decreased significantly. As oxygen concentration decreased, all pathways-derived N₂O rates increased, while the contribution of nitrifier denitrification remained unchanged. Key nitrifiers, including <em>Nitrososphaeraceae sp. TA-21, Nitrospira sp. Clade C</em> and comammox <em>Nitrospira kreftii</em>, regulated N₂O production across NH₄⁺-derived pathways, with their influence modulated by environmental context. These findings improve our understanding of N₂O production in agricultural ditches, providing insights into developing process-based models and mitigation strategies.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"16 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145229409","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":"Multifactorial environmental and ecological gradients from hydrology and land-use reflect coordinated plankton–organic pollutant spatial dynamics in coastal ecosystems","authors":"Frank Paolo Jay B. Albarico, Chiu-Wen Chen, Cheng-Di Dong","doi":"10.1016/j.watres.2025.124727","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124727","url":null,"abstract":"Coastal ecosystems are shaped by multifactorial gradients arising from hydrological regimes and land-use pressures, which orchestrate plankton biogeography and pollutant dynamics across spatial scales. However, the links between environmental forcing, plankton community structure, and organic pollutant bioaccumulation remain poorly understood in marine ecosystems. In this study, we explored how hydrology and land use together influence plankton communities and the accumulation of organic pollutants along 29 stations on Taiwan’s southwestern coast. Integrating physicochemical parameters, plankton assemblages, and compound-specific pollutant profiles (PAHs: 684 ± 987 ng/g, PAEs: 60,373 ± 30,376 ng/g, APs: 2,689 ± 1,561 ng/g) revealed coordinated ecological–chemical interactions. Univariate and multivariate analyses—including cluster analysis, exploratory factor analysis, network analysis, redundancy analysis, and canonical correspondence analysis—revealed significant (p &lt; 0.05) environmental and ecological gradients between northern and southern coasts. We identify two distinct ecological regimes: (1) hydrologically influenced northern sites dominated by <em>Thalassiosira</em> and crustacean larvae and eggs, exhibiting lower pollutant loads and nutrient-driven plankton stability; and (2) anthropogenically impacted southern sites characterized by <em>Chaetoceros</em>, copepods, and elevated pollutant bioaccumulation. Compound-specific drivers revealed that PAEs were modulated by zooplankton abundance and TN, APs by phytoplankton traits and TP, and PAHs by plankton biomass and SiO₂. These findings demonstrate that pollutant uptake is not merely concentration-dependent but emerges from ecological trait–nutrient–pollutant coupling shaped by environmental gradients in estuarine and coastal ecosystems. Overall, our findings advance ecological understanding of pollutant–plankton interactions and provide a foundation for developing bioindicator-based strategies to monitor and mitigate coastal pollution, while supporting urban planning in the anthropocene.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"1 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145229412","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":"Simulation of Polycyclic Aromatic Compounds in the Athabasca River Basin: Integrated Models and Insights","authors":"Qianyang Wang, Maricor J. Arlos, Jinqiang Wang, Mark McMaster, Erin Ussery, Colin A. Cooke, Brandon R. Hill, Nancy Glozier, Keegan A. Hicks","doi":"10.1016/j.watres.2025.124731","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124731","url":null,"abstract":"The environmental risks associated with polycyclic aromatic compounds (PACs) stemming from oil sands mining have become a concern in the Athabasca River basin (ARB), Alberta, Canada. Their complex environmental behavior complicates mechanistic, basin-scale modeling, making it difficult to assess the relevance of their sources, fate/transport, and potential impacts on exposed organisms. To address these challenges, a Python-based Soil Water Assessment Tool-Load Calculator (SWAT-LC) was developed and coupled with SWAT and Water Quality Analysis Simulation Program 8 (WASP8) models to describe PACs’ behavior in the ARB, including transport via surface runoff, soil lateral flow, groundwater baseflow, direct flux, and outcrop/sediment erosion. Chrysene, naphthalene, C4-phenanthrenes/anthracenes, and C4-dibenzothiophenes were selected to demonstrate the applicability of our modeling approach for simulating PACs of petrogenic and pyrogenic origins, diverse physico-chemical properties, and varying environmental relevance. The simulation results indicated that including the description of flow-driven natural outcrop erosion processes significantly enhanced model performance, while the temperature-dependent mechanism showed potential for improving erosion process characterization. Overall, the model performed well for chrysene, C4-phenanthrenes/anthracenes, and C4-dibenzothiophenes (NSE = 0.19∼0.75, <em>d</em> = 0.66∼0.95, PBIAS = -23∼47% at middle and downstream stations), but its performance was weaker for naphthalene (NSE = -2.16∼-0.40, <em>d</em> = 0.35∼0.53, PBIAS = 17∼51% at all target stations). Nonetheless, by integrating a comprehensive set of mechanistic processes, this model is now well-suited for scenario testing, especially for representative PACs that have major environmental and health relevance.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"1 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145229275","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":"Metal-free electrocatalytic dechlorination of chlorinated ethenes using bifunctional biochar cathode: adsorption-coupled electrocatalytic reduction mechanism","authors":"Lingzhi He, Siqi Wang, Yadong Yang, Zhuqi Chen","doi":"10.1016/j.watres.2025.124730","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124730","url":null,"abstract":"Electrochemical reductive dechlorination provides an environmentally friendly and sustainable method for the remediation of chlorinated ethenes (CEs) without chemical additives. However, the limited mass and electron transfer of commonly commercial electrodes restricts surface reactions with CEs. Herein, metal-free biochars (BCs) with high adsorption capacity (22.68∼51.32 mg/g) and conductivity (84∼303 Ω) were utilized as cathode materials for the effective dechlorination of CEs. The BC900 cathode exhibited a dechlorination efficiency of 98.14% for 10 mg/L trichloroethylene (TCE) within 24 hours, with a k_obs of 0.161 h⁻¹ under an applied potential of -1.0 V. Carbon balance and chloride form analyses indicated that nearly all C-Cl bonds were cleaved, with ethylene and acetylene identified as the primary end products. Quenching, kinetic, and electrochemical experiments demonstrated that the dechlorination process involves a direct electron transfer reduction pathway via conductive structures of BCs. Moreover, the synergistic effect on TCE dechlorination was superior to that of commercial electrocatalysts, achieving high reusability and wide adaptability in environmental water. This methodology can also be extrapolated to other CEs, including tetrachloroethylene, <em>cis</em>-1,2-Dichloroethylene, and vinyl chloride. These findings highlight an adsorption-coupled electrochemical reductive dechlorination mechanism for CEs, providing a theoretical foundation for the development of high-performance, biomass-based electrocatalysts in environmental applications.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"31 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145229410","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":"Blocking antibiotic resistance contamination dissemination to neutralized the impacts of bacterial oxidative stress via efficient photocatalysis","authors":"Yu Liu, Mingyang Xu, Likui Feng, Lingxin Zhao, Shufei He, Liangliang Wei","doi":"10.1016/j.watres.2025.124733","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124733","url":null,"abstract":"Transmission of antibiotic resistance genes (ARGs) in wastewater, which seriously threaten the ecological safety and human health, has attracted increasing attention recently throughout the world. However, the correlations between bacterial interaction and environmental stress in photo-inactivation are rarely studied. In this study, the efficient photo-treatment of ZIF@CF QDs-Fe for ARGs removal were explored, attributed to the superiority electric transfer rate and stable redox cycles of ZIF@CF QDs-Fe heterojunction. The experimental results revealed that the leaked e-ARGs and mobile genetic elements (MGEs) were immediately captured and attacked by the extracellular ROS (·OH, ·O₂^–), which could block the antibiotic-resistance dissemination. Meanwhile, ZIF@CF QDs-Fe photo-treatment further neutralized the negative effect of ROS induced oxidative stress, benefiting for the controlling of ARGs conjugative transfer. Combined with bacterial interactions, both the bacterial density and the abundance of dominant ARGs host was synergically reduced when the photo-treatment progressed, thus alleviating the ARGs natural dissemination risk. Meanwhile, the downregulation of transporter proteins and antibiotic target proteins elucidated that the ARGs transcription and bacterial reproduction were significantly suppressed under photo-inactivation. Interestingly, partial of the antibiotic bacterial sensitivity would be recovered through the regulations of bacterial functional expressions and further alleviated the potential ecological risk. Overall, these findings shed light on the inactivation mechanism of the nanomaterial mediated photo-treatment in blocking the resistance transfer pathways, giving valuable guidance for mitigating the antibiotic resistance dissemination in wastewater treatments.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"18 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145229414","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":"Overlooked role of singlet oxygen in electrochemical processes for efficient sludge dewatering at neutral pH","authors":"Jialin Liang, Yu Zhang, Liang Zhang, Xiao Xiao, Zhihua Mo, Yan Zhou","doi":"10.1016/j.watres.2025.124728","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124728","url":null,"abstract":"Conventional hydroxyl radical (•OH)-based treatments (i.e., iron-based advanced oxidation technologies (Fe-AOTs) and electrochemical processes) are generally considered efficient approaches for sludge dewatering via destroying the stable extracellular polymeric substances (EPS) structure in sludge. However, extremely acidic conditions (i.e., pH 2.8–3.2) in such processes hinder their commercial viability, primarily due to corrosive and environmental issues. Singlet oxygen (¹O₂), known for its selective oxidation and environmental stability, can break down protein structures even at low levels. ¹O₂-based processes may enable efficient sludge dewatering under neutral conditions by disrupting complex EPS structures. Therefore, in this study, we for the first time proposed a ¹O₂-based electrochemical process with a catalytic cathode of pyrite-modified graphite (electro-FeS₂@graphite) for sludge dewatering under neutral conditions. Results showed that under optimized conditions, the electro-FeS₂@graphite system achieved superior sludge dewatering (47.9% water content over ten cycles) compared to existing Fe-AOTs and electrochemical methods. Electron paramagnetic resonance, quenching tests, and reactive oxygen species probes confirmed that the FeS₂@graphite catalytic cathode mainly generated ¹O₂ species for efficiently eliminating hydrophilic aromatic structures and enhancing sludge dewatering without pH regulation. A three-step mechanism was proposed for the enhanced sludge dewaterability in the electro-FeS₂@graphite system: (i) <em>in situ</em> high H₂O₂ yield at FeS₂@graphite cathode, (ii) considerable ¹O₂ generation within the system, and (iii) selective attack on hydrophilic aromatic structures by ¹O₂. The operational cost of the proposed system was also substantially lower than that of the above-mentioned treatments. Overall, these findings highlight the effectiveness of ¹O₂-based electrochemical process in achieving stable and cost-effective sludge dewatering without acidification.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"45 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216191","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":"Photocatalysis-fueled algae-bacteria mutualism enables P450 enzyme-induced nitrite-free anammox for sustainable nitrogen removal","authors":"Tingjun Dong, Li Zhang, Jiachun Yang, Shiwei Hao, Yongzhen Peng","doi":"10.1016/j.watres.2025.124725","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124725","url":null,"abstract":"Anaerobic ammonium oxidation (anammox) relies on scarce nitrite in wastewater to produce hydroxylamine, a key substrate for anammox nitrogen removal, severely limiting its sustainable implementation. This study pioneers a photocatalysis-driven algae-bacteria mutualistic platform for activating a microalgal P450 enzyme-induced nitrite-independent anammox pathway. This platform integrates two functional blocks: photocatalysis-induced P450 activation circuit, and P450-mediated algal–anammox nitrogen removal module. <strong>First</strong>, photocatalysis rewired microalgal carbon flux to foster cooperation with heterotrophic ACID1, enabling ACID1-derived salicylic acid to feedback-regulate the biosynthesis of key P450 cofactors—iron–porphyrin and Fe–S clusters. Meanwhile, photogenerated electrons boosted NADPH (FC=2.33), directly fueling P450 activation. In this way, microalgal P450 enzymes were robustly activated to unprecedented levels, emerging as the most abundant protein family in CYAN1. <strong>Second</strong>, P450-catalyzed monooxygenation of ammonia to hydroxylamine bypassed nitrite, enabling a previously inaccessible microalgae–anammox synergistic nitrogen removal mode, achieving an ultra-high nitrogen removal efficiency of 99% without nitrite and with negligible greenhouse gas emissions. This strategy offers new insights into algal-bacterial cooperation and opens avenues for multi-channel solar-to-biochemical energy conversion in photocatalyst-microbe biohybrids for sustainable wastewater treatment.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"1 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216192","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":"Global insights into extracellular polymeric substances from activated sludge: Yield, composition, and microbial communities","authors":"Stefan De Bruin, Marie Riisgaard-Jensen, Susan Hove Hansen, Mark C.M. Van Loosdrecht, Per Halkjær Nielsen, Yuemei Lin","doi":"10.1016/j.watres.2025.124726","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124726","url":null,"abstract":"Activated sludge (AS) wastewater treatment generates substantial excess sludge which needs to be discarded and thereby increasing operational costs. Extracellular polymeric substances (EPS) within AS present a potential resource for recovery, reducing sludge volume and mass while adding value. Achieving this goal requires a better characterization of EPS, as the relationship between its composition and the microbial communities responsible for its production remains insufficiently understood. Here, we analysed extracted EPS from 16 wastewater treatment plants across 13 countries and 5 continents and found that alkaline extractable EPS yields varied widely (2.81–18.5 wt.% VSS). The microbial community composition of abundant species varied across plants and particularly across continents and did not correlate to the EPS yield. Only sludge retention time had a significant correlation with the EPS yield (p &lt; 0.005). Traditional colorimetric assays failed to detect compositional trends of the EPS, but Fourier Transform Infrared (FTIR) analysis indicated that extracted EPS from biological phosphorus removal systems had higher lipid and polysaccharide content, while chemical phosphorus removal systems had higher relative protein content. Thus, FTIR proved effective for distinguishing extracted EPS composition, demonstrating its potential as a high-throughput characterization tool. These findings highlighted that the wastewater treatment design and operation may shape the functional groups in EPS when using the alkaline method. More investigations are needed to find possible correlations between the composition of extracted EPS and the microbial community structure. Overall, the study presents a baseline for the amount and overall composition of biopolymers that can be extracted from global AS plants for recovery.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"28 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216193","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":"Preemptive activation of hypolimnetic oxygenation improves control of Fe and Mn in drinking water reservoirs","authors":"Cecelia E. Wood, Carly E. Bauer, Adrienne Breef-Pilz, Abigail S.L. Lewis, Nicholas W. Hammond, Ryan P. McClure, Mary F. Verne, Cayelan C. Carey, Madeline E. Schreiber","doi":"10.1016/j.watres.2025.124722","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124722","url":null,"abstract":"Seasonal anoxia in the hypolimnion of freshwater reservoirs can degrade water quality by promoting the release of iron (Fe) and manganese (Mn). To address these issues, hypolimnetic oxygenation (HOx) is an engineered treatment that aims to prevent upward diffusion of reduced Fe and Mn from anoxic sediments and to oxidize reduced Fe and Mn in the water column, enabling sedimentation and removal. However, quantification of the effect of HOx on Fe and Mn concentrations is challenging without a reference ecosystem for comparison and multiple years of monitoring data. In this study, we monitored dissolved Fe and Mn in the water column and Fe and Mn removal through sedimentation for six years in two temperate reservoirs – one with a HOx system and one without. Our results show that HOx significantly enhances Fe and Mn sedimentation in freshwater reservoirs, but sedimentation of Fe was much greater than Mn. When activated before the onset of anoxia, HOx substantially decreased the rates of Fe release into the water column. In contrast, although early HOx activation delayed Mn release, it did not decrease the Mn release rate into the water column. However, early HOx activation increased the Mn sedimentation rate. When HOx was activated after the onset of anoxia, maximum total Fe and Mn concentrations in the hypolimnion were approximately 4x and 1.6x greater than concentrations in years with preemptive activation. Our study indicates that HOx improves water quality with respect to Fe and Mn, especially when activated prior to the onset of anoxia.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"360 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216043","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":"Graphitic biochar-anammox achieved by multi-heme-based extracellular electron transfer","authors":"YanFei Tang, Eakalak Khan, April Z. Gu, Daniel C.W. Tsang","doi":"10.1016/j.watres.2025.124704","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124704","url":null,"abstract":"The anammox process decarbonizes nitrogen removal by avoiding greenhouse gas emissions and organic carbon demand, yet its reliance on nitrification and denitrification undermines these advantages. To address this, we developed a biochar-assisted anammox system that leverages graphitic defects as redox-active sites to enable interspecies, multi-heme extracellular electron transfer (EET). Biochar produced at 800 °C for 4 h (BC800-4h) exhibited the greatest graphitic defect density and the highest electron transfer capacity, uniquely exceeding the daily electron demand for complete ammonium oxidation in the present study. Metagenomic and in vitro assays revealed that BC800-4h promoted hydroxylamine-dependent ammonium oxidation by anaerobic ammonia-oxidizing bacteria (AnAOB) via EET. A cooperative microbial network was identified: AnAOB in suspension supplied heme precursors, while ammonia-oxidizing and denitrifying bacteria colonizing the biochar facilitated heme assembly and transport. This partitioning enabled direct electron transfer to biochar, achieving 62% nitrogen removal without exogenous nitrite and reducing N₂O emissions by 28%. The pore-size-dependent reduction in graphitic defects suggests that large molecular-weight biological channels (&gt;10 kDa) are essential for electron transfer between anammox bacteria and biochar. Our findings indicate an opportunity to develop a biochar-anammox reactor—with suspended AnAOB and a fixed-bed biochar biofilm—to exploit this synergy for efficient and low-emission nitrogen removal.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"1 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216206","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}