Water Research最新文献

{"title":"Attached microalgae-simulated plants enhanced multiple-pollutant removal in a tidal flow constructed wetland: quantified efficiencies, pathways, and biological mechanisms","authors":"Shu-Han Ge ,&nbsp;Mei-Zi Yang ,&nbsp;Wei-Yi Qian ,&nbsp;Lin-Lan Zhuang ,&nbsp;Hai-Ming Wu ,&nbsp;Zhuo Chen ,&nbsp;Xiao-Xiong Wang ,&nbsp;Jian Zhang","doi":"10.1016/j.watres.2025.124654","DOIUrl":"10.1016/j.watres.2025.124654","url":null,"abstract":"<div><div>Active microalgae have great potential for releasing organic carbon and oxygen, which can be utilized as electron donors/acceptors, to enhance pollutant removal in constructed wetlands (CWs). In this study, we proposed a tidal flow CW with attached microalgae-simulated plants (AMSP) and verified the superiorities and mechanisms of microalgae's contribution to pollutant removal. The CWs with AMSP achieved high removal efficiencies for NH₄_<img>N (87.6 %), TN (62.7 %), TP (56.4 %), and COD (98.8 %), which were 45.7 %, 16.3 %, and 20.5 % higher for NH₄_<img>N, TN, and TP compared with those without AMSP. AMSP were found to enhance the abundance of functional microorganisms and genes involved in nitrogen metabolism, and to reduce the pH values in the bed filler to improve phosphate adsorption. Furthermore, the enhancement of NH₄_<img>N and TP removal by AMSP was far beyond that of plants. Under the stress of 5 mg/L sulfamethazine (SMZ), the AMSP improved their photosynthetic efficiency and biomass accumulation, mitigated the impact of SMZ on the microbial community structure and diversity in the bed filler of CWs, increased the SMZ removal efficiency by 10.4 %, and reduced the release of antibiotics resistance genes into the environment by 49.7–89.6 %. These results demonstrated an effective integration of microalgal cultivation and CWs for treating wastewater containing emerging contaminants.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"288 ","pages":"Article 124654"},"PeriodicalIF":12.4,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145103702","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":"Enantioselective interactions of silver nanoparticles and chiral antibiotics in driving resistance evolution in activated sludge","authors":"Fang Zhao ,&nbsp;Zhao Yang ,&nbsp;Yifan Xiao ,&nbsp;Ganghua Han ,&nbsp;Kim R. Hardie ,&nbsp;Mark Bartlam ,&nbsp;Yingying Wang","doi":"10.1016/j.watres.2025.124656","DOIUrl":"10.1016/j.watres.2025.124656","url":null,"abstract":"<div><div>The stereochemistry of antibiotics significantly affects resistance development. With rising antibiotic resistance, nanotechnology is emerging as a promising solution, potentially increasing the likelihood of nanoparticle coexistence with antibiotics in wastewater treatment plants (WWTPs). However, the influence of nanoparticles on chiral antibiotics induced resistance remains unclear. This study employed chemical characterization, metagenomics, and molecular docking to comprehensively elucidate the resistance mechanisms induced by the combination of silver nanoparticles (AgNPs) and chiral antibiotics (ofloxacin: OFL and levofloxacin: LEV). AgNPs significantly altered the abundance and composition of antibiotic and metal resistance genes, as well as the conjugative transfer of the RP4 plasmid among activated sludge communities, with the OFL_AgNPs combination exhibiting a higher resistance potential than LEV_AgNPs. Mechanistic studies revealed that chiral antibiotics selectively interact with AgNPs, promoting Ag⁺ release, enhancing antibiotic uptake, and forming stable complexes. These interactions reshaped microbial functions, including cell membrane permeability, oxidative stress response, quorum sensing, and extracellular secretion, thereby shaping resistance profiles. This study reveals previously overlooked enantiomer-specific risks associated with nanoparticle-antibiotic interactions and provides a foundation for strategies to mitigate ARG dissemination in wastewater treatment and broader environmental systems.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"288 ","pages":"Article 124656"},"PeriodicalIF":12.4,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116808","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":"Crosstalk with Chlorella sp. Reshapes the Environmental Fates of Aspartame: From Stress Responses to Contaminant Destabilization","authors":"Longfei Zhang, Roger Ruan, Yuhuan Liu, Qihang Yin, Cuixia Liu, Zhigang Yu, Yunpu Wang, Xian Cui, Qi Zhang","doi":"10.1016/j.watres.2025.124650","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124650","url":null,"abstract":"Aspartame (APM) is demonstrated to facilitate the dissemination of antibiotic resistance genes and react with residual chlorine in tap water to form cytotoxic disinfection byproducts, indicating potential ecological risks. However, it remains unclear whether microalgae, as primary producers and bioindicators, interact with APM and its transformation products (APM-TPs), or whether microalgae modify their environmental fates, thereby reshaping APM-associated risks. Here, we found that APM inhibited the growth of <em>Chlorella</em> sp. in a concentration-dependent manner (growth inhibition rate: -16.6% to 24.4%), altered the composition of photosynthetic pigments, and induced oxidative damage. Spiking experiments of APM-TPs confirmed (2S,5S) 5-Benzyl-3,6-dioxo-2-piperazineacetic acid ((2S,5S)-DKP) as the primary inducer of oxidative stress in <em>Chlorella</em> sp. Targeted and non-targeted high-resolution mass spectrometry elucidated transformation pathways of APM under hydrolytic, photolytic, and <em>Chlorella</em> sp. conditions. Meanwhile, the conversion of APM to (2S,5S)-DKP was 75.6%-97.0% in water samples from the Yangtze River, Yellow River, and Ganjiang River, further elucidating the environmental fates of APM in natural water system. Notably, the first evidence of <em>Chlorella</em> sp.-catalyzed isomerization of (2S,5S)-DKP, with an isomerization rate of 46.7%, was demonstrated. Finally, transcriptomics revealed mechanisms of APM-induced oxidative stress, photosynthetic impairment, and energy metabolism dysregulation in <em>Chlorella</em> sp. This study comprehensively elucidated the interaction mechanisms between APM and <em>Chlorella</em> sp., providing novel insights into the environmental geochemical behaviors of APM and (2S,5S)-DKP.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"67 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145093627","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":"Simultaneous aerobic stabilisation of sewage sludge and chelator-assisted removal of toxic metals in a closed-loop process","authors":"Barbara Fojkar,&nbsp;Domen Lestan","doi":"10.1016/j.watres.2025.124653","DOIUrl":"10.1016/j.watres.2025.124653","url":null,"abstract":"<div><div>Sewage sludge is a valuable source of phosphorus but contains toxic metals that hinder its use as fertilizer. We present a novel process that simultaneously stabilises sludge through post-aerobic digestion (12 days, pH 5.8–7.6, solid-to-liquid ratio 1:25 (dry w/v)) and removes toxic metals using ethylenediaminetetraacetate (EDTA, 10 mM). On average, 74.4% of EDTA was successfully recycled by alkalinization of process solution with quicklime (CaO) to pH 12.5 and reused in subsequent batches. Chelator losses were compensated by the addition of Na-EDTA. Toxic metals, along with excess Ca and Na, were effectively removed from the recycled process solution, enabling closed-loop operation without wastewater generation. During five consecutive batches, total solids in the sludge were reduced by an average of 23.2%, and 74, 61, 26, and 43% of Zn, Cu, Cr, and Pb, respectively, were removed. The leaching of residual toxic metals from the stabilised and decontaminated sludge was further reduced by 55–88% through the addition of zero-valent iron (3% dry w/w). The process also increased the phosphorus concentration in the sludge by 15% and improved its phytoavailability up to 1.8-fold (as determined by ammonium-lactate extraction). This process is sustainable: it preserves valuable nutrients, can be integrated into existing wastewater treatment plant operations, generates only 17% solid waste (relative to the dry weight of the sludge), and produces no wastewater. Due to the recycling of costly EDTA, reagent costs were halved, reaching €73 t^-1 of dry sludge.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"288 ","pages":"Article 124653"},"PeriodicalIF":12.4,"publicationDate":"2025-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145093610","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":"Dynamics of blue carbon across various estuaries: Key drivers and pathways","authors":"Sha Lou, Zhongyuan Yang, Shizhe Chen, Shuguang Liu, Gangfeng Ma, Irina Viktorovna Fedorova","doi":"10.1016/j.watres.2025.124644","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124644","url":null,"abstract":"Coastal wetlands are vital organic carbon (OC) sinks. This study examined OC dynamics and the implications for trophic status in the salt marsh-dominated Yangtze River Estuary (YRE) in China and four mangrove-dominated estuaries under varying anthropogenic influence within the Rookery Bay National Estuarine Research Reserve (RBNERR) in the USA, including natural (FHE), agricultural (BWE), canal-modified (FUE), and urbanized (HCE) estuaries. The research focused on three thematic areas: total organic carbon (TOC) composition and degradation, key drivers and their cascading effects, and estuarine eutrophication assessment, employing stable isotope tracing (δ¹³C, C/N), machine learning (BRT models), partial least squares path modeling (PLS-PM), and trophic indices (TRIX, TSI). Results showed that FHE had the highest organic carbon concentrations (4-19.82 mg/L). While terrestrial sources contributed &gt;85% of total OC across estuaries, composition varied: YRE's OC was derived mainly from freshwater algae and soil organic matter, whereas in the RBNERR estuaries, it was dominated by mangrove-derived, marine phytoplankton, and anthropogenic sources. Anthropogenic organic matter (OM) inputs (e.g., from agriculture and wastewater) and phytoplankton growth promoted r-strategists and enhanced degradation, likely decreasing burial efficiency in YRE, BWE, and HCE compared to FHE and FUE. In the FHE and FUE, TOC was primarily driven by the degradation of mangrove-derived OM (with hydrodynamic influence in FUE). In contrast, TOC in the YRE, BWE, and HCE estuaries was mainly governed by anthropogenic and phytoplankton inputs, which manifested in distinct ways: tidal dilution, light-limited photosynthetic growth, and degradation of phytoplankton-derived and soil organic matter in the YRE; agricultural organic matter degradation in the BWE; and phytoplankton photosynthesis in the HCE. PLS-PM further revealed that meteorological factors indirectly influenced TOC concentrations through salinity, biological environment, hydrodynamics and nutrients. Overall, the driving mechanisms resulted in the YRE and BWE being eutrophic, while the other estuaries were mesotrophic. In summary, these findings demonstrate that local environmental factors and human activities are key drivers of OC dynamics. This understanding of specific mechanisms is essential for refining blue carbon assessments under global change.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"22 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089278","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":"Brominated organic compounds in leachate across China: Occurrence and molecular variations","authors":"Jing Zheng, Ji-Tao Lv, Yue Sun, Qing-Yu Liu, Qiu-Rui Zhang, Zi-Meng Wang, Xiao-Song He","doi":"10.1016/j.watres.2025.124647","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124647","url":null,"abstract":"At present, China is the world’s largest producer and consumer of brominated flame retardants (BFRs). Substantial quantities of BFRs are washed out of waste from landfill and incineration sites, and are become part of the contaminated leachate. However, the occurrence and molecular variations of brominated organic compounds (BOCs) in leachate across China remains largely unexplored. Upon collecting leachate samples from 87 landfill or incineration sites throughout China, the BOCs are explored using Fourier transform ion cyclotron resonance mass spectrometry coupled with the neutral model. The results show that ∼80.5% of the leachate samples contain no more than 30 brominated organic molecules (BOMs), and 347 BOMs are detected across China, with monobrominated organic molecules constituting 86.5%. These identified BOMs include aliphatics (123 types), polyphenols (67 types), condensed aromatics (68 types), amino sugar (42 types), and carbohydrates (19 types). They possess 5–12 carbon atoms and are highly unsaturated, strongly aromaticit, and less biodegradable. Evidently, the molecular variations of BOCs are more stochastic in landfill leachate compared with those in incineration leachate. This study presents a nontargeted survey of BOCs in leachate at a national scale in China, providing a scientific basis for risk assessment and pollution control of BOCs in leachate.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"41 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145093589","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":"Self-regenerable zeolite Beta(35) for efficient adsorption and photocatalytic degradation of PFOA under simulated solar irradiation","authors":"Xiaoyu Li,&nbsp;Xuejing Xiao,&nbsp;Shengnan Zhang,&nbsp;Xiaolei Teng,&nbsp;Zunyao Wang,&nbsp;Ruijuan Qu","doi":"10.1016/j.watres.2025.124645","DOIUrl":"10.1016/j.watres.2025.124645","url":null,"abstract":"<div><div>Perfluorooctanoic acid (PFOA), a priority emerging pollutant, necessitates efficient and green removal methods. While adsorption is cost-effective under mild conditions, the adsorbent treatment often causes additional costs and limits its applicability. This study employs a BEA-topology zeolite (Beta(35)) as a bifunctional adsorbent and photocatalyst for PFOA removal. Beta(35) at a dosage of 0.25 g/L achieved 90.7 % adsorption of 20 mg/L PFOA within 1 h, with adsorption capacities reaching 80 mg/g. Under natural sunlight irradiation, Beta(35) demonstrated 85.2 % degradation efficiency and 63.1 % defluorination efficiency for PFOA within 24 h. Additionally, the feasibility of treating trace PFOA-contaminated water was confirmed, where 2 g of Beta(35) effectively enriched and degraded 4 L of simulated groundwater containing 50 μg/L PFOA, achieving a degradation efficiency of 94.1 % within 48 h. Theoretical calculations and spectral analyses confirmed that PFOA adsorbs onto the acidic sites of Beta(35) through bidentate/bridging coordination, reducing the C<img>C bond dissociation energy at the carboxyl end to facilitate degradation. Besides, the complexation of Beta(35) and PFOA improved the photocatalytic performance of Beta(35), facilitating the formation of <em>h</em>⁺ and ROS (•OH and •O₂⁻). Beta(35) remove aqueous PFOA via initial adsorption followed by photocatalytic degradation for self-regeneration, offering a sustainable and cost-effective solution for PFAS remediation.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"288 ","pages":"Article 124645"},"PeriodicalIF":12.4,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089532","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":"Intermittent glycerol feeding shapes a glycogen-storing phenotype for enhanced nitrite accumulation via sequential denitrification","authors":"Shi-Man Liang,&nbsp;Jia-Qi Zhou,&nbsp;Hai-Tian Xu,&nbsp;Shu-Yang Fang,&nbsp;Yu Zhang,&nbsp;Zheng-Zhe Zhang,&nbsp;Ren-Cun Jin","doi":"10.1016/j.watres.2025.124646","DOIUrl":"10.1016/j.watres.2025.124646","url":null,"abstract":"<div><div>Achieving stable and efficient denitratation is a promising strategy to supply nitrite for mainstream anammox processes, yet the underlying microbial mechanisms remain poorly understood, especially with alternative carbon sources like glycerol. Here, we hypothesized that intermittent feeding regimes could drive higher nitrite accumulation by selecting for specific metabolic phenotypes. To test this, an intermittently-fed sequencing batch reactor (SBR) and a continuously-fed up-flow anaerobic sludge blanket (UASB) reactor were operated under identical carbon-restricted conditions (COD/NO₃⁻-<em>N</em> = 3.5). The SBR achieved a significantly higher and stable nitrite accumulation efficiency (NiAE) of 43.0 ± 4.1 % compared to the UASB (18.9 ± 5.4 %). Genome-resolved metagenomics revealed that the SBR community was enriched in species with glycogen-storing potential, leading to a 45.8 % greater overall abundance of genes related to glycogen metabolism compared to the UASB. Phenotypic analyses confirmed that the SBR sludge contained significantly more intracellular glycogen and displayed a nitrate reductase (NAR) to nitrite reductase (NIR) activity ratio that was an order of magnitude higher than the UASB sludge. This kinetic imbalance underpinned a “sequential denitrification” phenotype, where nitrate was preferentially reduced to nitrite. Critically, the UASB-enriched community, when subjected to batch-fed conditions, also exhibited a high denitratation potential close to the SBR culture, demonstrating that this phenotype is a plastic trait regulated by the glycerol feeding strategy rather than a fixed attribute of the community structure. This study uncovers a fundamental mechanism where intermittent glycerol availability directs metabolic flux towards glycogen storage, which in turn regulates electron partitioning between NAR and NIR. This highlights a significant divergence between genotypic potential and realized phenotype, offering a new paradigm for controlling nitrogen transformation pathways in engineered ecosystems.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"288 ","pages":"Article 124646"},"PeriodicalIF":12.4,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089280","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":"Dual-Pathway Inhibition of Antibiotic Resistance Genes by Ferrate (Fe(VI)): Oxidative Inactivation and Genetic Mobility Impairment in Anaerobically Digested Sludge","authors":"Tianyi Luo, Xiaohu Dai, Yuting Zhang, Wei Wei, Bing-Jie Ni","doi":"10.1016/j.watres.2025.124648","DOIUrl":"https://doi.org/10.1016/j.watres.2025.124648","url":null,"abstract":"Antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) are emerging environmental contaminants that threaten public health, highlighting the urgent need for effective control strategies. Ferrate (Fe(VI)), a strong and eco-friendly oxidant, shows great potential for this purpose. This study systematically evaluated the efficacy of Fe(VI) in mitigating ARGs and ARB in anaerobically digested sludge, with a particular focus on elucidating the underlying mechanisms by which Fe(VI) effects ARGs dissemination through both vertical gene transfer (VGT) and horizontal gene transfer (HGT). Result shows that Fe(VI) doses of 20 and 60 mg/g-TS reduce ARGs by 9.75% and 19.12%, respectively, while inactivating up to 24.7% of ARB at the higher dose. Pathogenic ARB, such as <em>Escherichia coli</em> and <em>Shigella sonnei,</em> are preferentially removed, with abundances decrease by 63.7% and 28.0%. Mechanistically, the structural disruption of bacterial cells caused by Fe(VI) in anaerobically digested sludge, as indicated by a 29% reduction in extracellular polymeric substances and a 23.7% increase in cell membrane permeability. Subsequently, a marked release of intracellular ARGs into the extracellular environment is also observed, where they are likely subjected to degradation by Fe(VI). This oxidative killing accounts for the observed ARB decrease, thereby limiting the VGT of ARGs. In addition, Fe(VI) impairs the HGT of ARGs by diminishing their mobility potential, reflected in the reduced co-occurence with mobile genetic elements. Meanwhile, sludge bacterial competence for DNA uptake and recombination is markedly reduced, as evidenced by a 9.8% decline in the abundance of related functional genes. These findings demonstrate that Fe(VI) effectively inhibits the dissemination of ARGs by targeting both primary transmission pathways. It suppresses VGT, thereby reducing the inheritance of ARB within populations, and limits HGT, curbing the spread of mobile ARGs among competent species. By disrupting these two critical routes, Fe(VI) shows strong potential as an effective strategy for mitigating ARGs propagation in sludge systems.","PeriodicalId":443,"journal":{"name":"Water Research","volume":"53 1","pages":""},"PeriodicalIF":12.8,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145093588","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":"Low dissolved oxygen nitrification through kinetic selection","authors":"Jose Jimenez ,&nbsp;Kayla Bauhs ,&nbsp;Mark Miller ,&nbsp;Peter Dold ,&nbsp;Ahmed Al-Omari ,&nbsp;Manel Garrido ,&nbsp;Dev Hiripitiyage ,&nbsp;Megan Wittman ,&nbsp;Gillian Burger ,&nbsp;Kartik Chandran ,&nbsp;Belinda Sturm","doi":"10.1016/j.watres.2025.124642","DOIUrl":"10.1016/j.watres.2025.124642","url":null,"abstract":"<div><div>Recent research in wastewater treatment demonstrates that activated sludge plants can be operated more efficiently in terms of energy and carbon utilization without the need for new infrastructure through the implementation of low dissolved oxygen (DO) operation. The aim of this study was to understand how microbial communities adapt to long-term low DO operations and the implications for nitrification. This study synthesized findings from bench-scale and full-scale experiments to assess the impact of low DO operation on nitrification rates, microbial community structure, and nitrous oxide (N₂O) generation. Long-term exposure to low DO conditions led to a shift in the nitrifier community structure, favoring comammox bacteria (CMX) and, in some cases, ammonia-oxidizing archaea (AOA) over canonical ammonia-oxidizing and nitrite-oxidizing bacteria (AOB, NOB). In conventional high-DO systems, the ratio of nitrate production rate to ammonia removal rate is approximately 0.78, reflecting the lower growth rate of NOB compared to AOB. However, in the low DO facilities studied, this ratio approached 1.0, indicating that nearly all ammonia removed was directly converted to nitrate. This finding strongly supports the dominance of CMX which can perform complete ammonia oxidation in a single organism. The correlation between increased CMX abundance and increased nitrate production rates was consistent across facilities operating at different DO levels. These adapted communities demonstrated higher oxygen affinity compared to AOB and NOB from plants operated at high DO concentrations. Long-term exposure of biomass to low DO concentration may have resulted in a decrease in N₂O emissions since there is a low relative abundance of AOB and NOB, limiting N₂O production via the hydroxylamine oxidation pathway and nitrifier denitrification by AOB.</div></div>","PeriodicalId":443,"journal":{"name":"Water Research","volume":"288 ","pages":"Article 124642"},"PeriodicalIF":12.4,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089378","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}