Shiyang Chen, Fabian Funke, Guangqi Liu, Frans van de Ven, Xiaowen Cheng, Chris Zevenbergen, Wolfgang Rauch, Manfred Kleidorfer
{"title":"Operationalising storage-discharge balance to enhance pluvial flood resilience: modelling and planning strategies in flat and sloping urban areas.","authors":"Shiyang Chen, Fabian Funke, Guangqi Liu, Frans van de Ven, Xiaowen Cheng, Chris Zevenbergen, Wolfgang Rauch, Manfred Kleidorfer","doi":"10.2166/wst.2026.333","DOIUrl":"https://doi.org/10.2166/wst.2026.333","url":null,"abstract":"<p><p>Storage and discharge are two fundamental solutions to strengthening pluvial flood resilience. Recent studies reveal that many urban catchments operate under a persistent storage-discharge imbalance, driven by urban densification. This 'imbalance' raises concerns in hydrologic, economic, spatial, and social aspects. This research aims to quantify the balanced relationship between storage capacity and discharge capacity (storage discharge balance, SDB) for pluvial flood protection and provide planning strategies for different urban topographies. We suggest and apply a quantification method using different modelling tools, hydrological and hydrodynamic models, in two cases with distinct physical and socioeconomic characteristics: one in a flat polder area in Nanjing, China, and the other in a sloping hilly area in Feldbach, Austria. By comparing these cases, insights are gained into the modelling methods, results, and proposed strategies for each context. The use of the SDB chart mapping framework supports the identification of both short- and long-term targets, as well as dynamic pathways toward enhanced flood resilience. These insights will facilitate multidisciplinary dialogue on key constraining factors, thereby enabling the co-creation of an actionable solution. While the quantitative findings are context-dependent, the novel approach can be applied to other cities to facilitate their resilience planning.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 4","pages":"475-492"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148867133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Amjad Khan, Yoonkyung Park, KyungHo Kwon, Reeho Kim
{"title":"Long-term permeability of permeable pavement in an urban area: a case study of Seoul, South Korea.","authors":"Amjad Khan, Yoonkyung Park, KyungHo Kwon, Reeho Kim","doi":"10.2166/wst.2026.325","DOIUrl":"https://doi.org/10.2166/wst.2026.325","url":null,"abstract":"<p><p>Permeable pavement systems are a key low-impact development strategy for mitigating rainfall runoff in urban environments. However, their long-term effectiveness is often compromised by clogging from particulate matter, which progressively reduces permeability. This study evaluates long-term permeability of PPs installed at 13 sidewalk locations in Seoul, South Korea, over 38 months (May 2018-June 2021) using in-situ tests (KS F 2394). Results show that by the end of monitoring, eight sites had declined to Grade 5 (lowest classification), while five sites maintained Grade 3. According to Seoul guidelines, the minimum recommended permeability is Grade 3. These findings indicate that more than half of the sites fell below the recommended standard within 3 to 5 years of installation, highlighting the critical need for regular maintenance. The study aligns with recent research demonstrating that pressure washing can effectively restore permeability in clogged pavements. Based on these results, a guideline revision is proposed: adding a new top category (Grade 0) for superior permeability (≥1.5 mm/sec) and raising the minimum recommended permeability to Grade 2 to ensure longer-term performance before maintenance is required. Future research should develop more efficient cleaning techniques to sustain the hydrological function of existing permeable pavement installations in urban areas.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 4","pages":"493-505"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148867089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Juan Fausto Ortiz-Medina, Jeel Jasoliya, Isabel Angulo, Dongwon Ki, César I Torres
{"title":"Kinetic response of hydrogen peroxide conversion to oxygen and subsequent biological respiration during activated sludge treatment.","authors":"Juan Fausto Ortiz-Medina, Jeel Jasoliya, Isabel Angulo, Dongwon Ki, César I Torres","doi":"10.2166/wst.2026.330","DOIUrl":"https://doi.org/10.2166/wst.2026.330","url":null,"abstract":"<p><p>For decades, activated sludge has been utilized to remove organic components from wastewater. In this process, required oxygenation is typically energy-intensive. Hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) poses an energy-saving alternative to generate catalase-driven oxygen (O<sub>2</sub>). However, assessing its viability in activated sludge has been limited to stoichiometric respiration demands. In this study, specific H<sub>2</sub>O<sub>2</sub> concentrations were tested on artificial wastewater to obtain predictable kinetic rates for peroxide addition, O<sub>2</sub> production, and substrate removal by a native sludge community. Batch injections of 25-50 mg H<sub>2</sub>O<sub>2</sub>/L result in fast conversion to O<sub>2</sub> whose response could be modeled through Michaelis-Menten kinetics. Calculated production rates are at least tenfold higher than oxygen uptake rates, with the latter comparable to typical AS systems. Based on consumption rates, continuous feeding (28 mg H<sub>2</sub>O<sub>2</sub>/g MLSS-h) achieved complete substrate conversion at 1.1 g COD/L-d. Higher feeding rates eventually resulted in minimal O<sub>2</sub> uptake and incomplete substrate removal, which recovered after stopping H<sub>2</sub>O<sub>2</sub> feeding. Comparatively, nitrification was not inhibited by increased peroxide feeding. Our results provide consistent O<sub>2</sub> generation and direct responses to leverage direct H<sub>2</sub>O<sub>2</sub> utilization in existing WWTPs, where the experimental framework determines relevant feeding rates to be met by <i>in situ</i> H<sub>2</sub>O<sub>2</sub>-producing technologies during activated sludge treatment.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 4","pages":"506-520"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148867084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Ruman Uddin, Abdul Ahad, Samsul Islam, Md Yeasin, Md Moshedul Islam, Tasnim Alam Sayedi, Amanullah Moral, Akib Atique Khan Dhrubo
{"title":"Sustainable treatment of textile wastewater using a bio-based batch filtration system: physicochemical performance assessment and economic evaluation.","authors":"Ruman Uddin, Abdul Ahad, Samsul Islam, Md Yeasin, Md Moshedul Islam, Tasnim Alam Sayedi, Amanullah Moral, Akib Atique Khan Dhrubo","doi":"10.2166/wst.2026.320","DOIUrl":"https://doi.org/10.2166/wst.2026.320","url":null,"abstract":"<p><p>Textile industries generate large volumes of wastewater, containing high concentrations of organic pollutants, dissolved solids, and suspended particles, requiring eco-friendly and cost-effective treatment technologies. This study developed a gravity-driven bio-based batch filtration system using sugarcane bagasse fiber and coconut fiber to investigate textile wastewater treatment performance and economic feasibility. Five bagasse-to-coconut fiber ratios (100:0, 0:100, 50:50, 75:25, and 25:75) were evaluated in a multilayer filtration system. Scanning electron microscope and Fourier transform infrared analyses were performed to characterize the fiber morphology and adsorption-active functional groups before and after filtration. Among all filter configurations, the 50:50 fiber ratio demonstrated the best overall performance, achieving removal efficiencies of 79.33% for biological oxygen demand, 75.75% for chemical oxygen demand, 80.00% for total dissolved solids (TDS), 46.51% for turbidity, 77.45% for electrical conductivity (EC), and 4.82% for pH after a single filtration cycle, while maintaining pH within the Bangladesh Department of Environment permissible range. Sequential treatment cycles further enhanced treatment efficiency, achieving an overall removal of 89.17% for TDS, 81.52% for turbidity, and 88.63% for EC after five filtration cycles. Economic evaluation demonstrated a unit treatment cost of approximately 90.71 BDT/m<sup>3</sup>, significantly lower than activated carbon-based systems. These findings suggest that the proposed bio-based filtration system provides an economical, energy-free, and sustainable alternative for resource-limited regions such as Bangladesh.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 4","pages":"521-542"},"PeriodicalIF":2.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148867098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Runoff simulation and prediction in a water source area of a typical urban agglomeration.","authors":"Zhaohui Feng, Zichao Zhang, Lingqing Wang, Yingyi Meng, Guangjin Zhou, Yizhong Huan","doi":"10.2166/wst.2026.293","DOIUrl":"10.2166/wst.2026.293","url":null,"abstract":"<p><p>The dynamics of water resources in the strategic water source areas of the Beijing-Tianjin-Hebei region under combined scenarios of future climate change, land-use evolution, and social vulnerability remain unclear. The current runoff status of the water source area in the Beijing-Tianjin-Hebei region was simulated and predicted using the Soil and Water Assessment Tool (SWAT). The runoff simulation showed that <i>R</i><sup>2</sup> values were 0.76 for the calibration period (2009-2016) and 0.97 for the validation period (2017-2018). Multiple simulation scenarios showed warming climate trends in the future. In the future prediction, the runoff in the SSP585 scenario decreased by 36.31% (2041-2050) and 5.96% (2051-2060), respectively. The results indicated that high radiative forcing and high social vulnerability were not conducive to future water resource replenishment and sustainable development, highlighting potential challenges for maintaining water resources under combined climate and social pressures.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 1","pages":"70-87"},"PeriodicalIF":2.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148456644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Michael Cimbritz, Per Falås, Alexander Betsholtz, Ellen Edefell, Simon Gidstedt, Maria Takman, Ola Svahn, Åsa Davidsson
{"title":"Removal of organic micropollutants in granular activated carbon filters - review of long-term and full-scale experiences from municipal wastewater treatment.","authors":"Michael Cimbritz, Per Falås, Alexander Betsholtz, Ellen Edefell, Simon Gidstedt, Maria Takman, Ola Svahn, Åsa Davidsson","doi":"10.2166/wst.2026.313","DOIUrl":"10.2166/wst.2026.313","url":null,"abstract":"<p><p>Granular activated carbon (GAC) filtration is increasingly used for quaternary treatment of municipal wastewater to remove organic micropollutants, in line with the revised EU Urban Wastewater Treatment Directive (Directive (EU) 2024/3019). This review compiles and synthesises available, peer-reviewed, and long-term pilot- and full-scale studies and, in contrast to previous reviews, particularly addresses breakthrough of Urban Wastewater Treatment Directive (UWWTD) relevant indicator compounds in relation to operational lifespan and regulatory compliance. Most studies were conducted at pilot scale, with considerable variation in empty bed contact time, filtration rate, and GAC type. Breakthrough of indicator compounds varied widely, but citalopram, metoprolol, benzotriazole, and methylbenzotriazole generally showed relatively late breakthrough, indicating potential for longer filter lifespan, whereas candesartan and irbesartan more often showed early breakthrough. The available data further indicate that the selection of indicator compounds strongly affects the operational lifespan over which compliance with the UWWTD may be maintained. However, the limited number of long-term full-scale studies and the large variability in pre-treatment, filter design, carbon type, and operating conditions prevent robust quantitative assessment of these relationships. The findings highlight the need for more large-scale, long-term studies using a systematic evaluation framework to support the effective implementation of GAC filtration for UWWTD compliance.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 1","pages":"108-122"},"PeriodicalIF":2.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148457058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Qian Yang, Qinghua Yang, Xianzhi Wang, Xiao He, Wei Li
{"title":"Numerical investigation on hydraulic characteristics and control measures of the geyser induced by the entrapped air release in a baffle-drop shaft.","authors":"Qian Yang, Qinghua Yang, Xianzhi Wang, Xiao He, Wei Li","doi":"10.2166/wst.2026.308","DOIUrl":"10.2166/wst.2026.308","url":null,"abstract":"<p><p>To reduce structural and ground safety hazards induced by high-speed air-water mixtures during geyser events inside baffle-drop shafts, a three-dimensional numerical simulation was carried out. This work systematically investigates how void fraction and inlet pipe diameter influence internal pressure and geyser strength, analyzes the distribution of impact loads acting on bottom baffles, and proposes mounting a throttling orifice plate at the shaft midsection to suppress violent geysers. Results reveal inlet pipe pressure declines first then rises as void fraction grows, hitting the lowest value within the void fraction range of 0.2-0.4. Geyser intensity peaks when the diameter ratio of the inlet pipe to the drop shaft equals 1:2. Moreover, baffle impact loads gradually weaken from the shaft bottom upward; loads near partition and shaft walls far exceed those at baffle edges. A midshaft orifice plate delivers reliable geyser suppression, yet it bears impact loads 10 times larger than those on bottom baffles. The conclusions provide practical guidance for the safety-oriented structural design of baffle-drop shafts.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 1","pages":"29-44"},"PeriodicalIF":2.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148457089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Lili Wang, Sijie Zhou, Rongxiang Zhang, Xianbin Liu, Ying Li
{"title":"Enhanced rapid acclimation of nitrifying sludge to sulfamethoxazole stress via exogenous quorum-sensing signal molecules.","authors":"Lili Wang, Sijie Zhou, Rongxiang Zhang, Xianbin Liu, Ying Li","doi":"10.2166/wst.2026.303","DOIUrl":"10.2166/wst.2026.303","url":null,"abstract":"<p><p>Nitrifying sludge is capable of simultaneous removal of high-concentration ammonia nitrogen and sulfamethoxazole (SMX). Quorum sensing mediated by acyl-homoserine lactones (AHLs) has emerged as a potential regulatory tool to modulate microbial community function and stress resistance. However, the effects of AHLs on nitrifying sludge under SMX stress remain unclear. This study aimed to investigate whether AHLs can facilitate the acclimation of nitrifying sludge under SMX exposure. Sequencing batch reactor experiment results demonstrated that under the shock loading of 500 μg/L SMX, the addition of 2 μM C6-HSL maintained significantly higher NH<sub>4</sub><sup>+</sup>-N removal efficiency and nitrite accumulation rate, compared with the 2 μM 3-oxo-C6-HSL group, and the mixed addition group of C6-HSL and 3-oxo-C6-HSL. Meanwhile, under the action of C6-HSL, nitrifying sludge exhibited a steadily increasing SMX removal efficiency starting from Day 12, which was earlier than other groups. From a microscopic perspective, the individual addition of AHLs stimulated the secretion of EPS and the growth of functional bacteria, whereas the combined addition group resulted in the opposite effect. The combined addition of AHLs enhanced the capacity o<u>f</u> converting nitrite to nitrate, while attenuating its denitrification ability. This study provides a theoretical basis for the rapid adaptation of biological processes to SMX-contaminated wastewater.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 1","pages":"215-228"},"PeriodicalIF":2.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148457086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Martin Oberascher, Amin E Bakhshipour, Karim Sedki, Arnold Autengruber, Arno Kahl, Sina Hesarkazzazi, Ali Haghighi, Ulrich Dittmer, Robert Sitzenfrei
{"title":"Evaluation of the explainability and reliability of two surrogate models for predicting outflow of combined sewer systems.","authors":"Martin Oberascher, Amin E Bakhshipour, Karim Sedki, Arnold Autengruber, Arno Kahl, Sina Hesarkazzazi, Ali Haghighi, Ulrich Dittmer, Robert Sitzenfrei","doi":"10.2166/wst.2026.296","DOIUrl":"10.2166/wst.2026.296","url":null,"abstract":"<p><p>Urban drainage networks (UDNs) are designed to reliably discharge wastewater and stormwater, with machine learning (ML) increasingly leveraged for a wide range of applications. A legal assessment of the European 'Artificial Intelligence Act' (AI Act) indicates that, while UDNs are considered part of critical infrastructure, ML applications in this field are generally not classified as high-risk AI systems, being subject to specific implementation requirements. Nevertheless, aspects such as model explainability are important to align with best practices in ML model development. In this context, two ML models (i.e., purely data-driven and physics-leveraged) used herein as surrogates for hydrodynamic modelling to predict combined sewer flow, were adapted from the authors' previous work and enhanced with various explainable AI techniques such as SHapley Additive exPlanations and robustness scores for a comprehensive understanding of the models' decision-making processes. The analysis revealed that the engineered classification into dry or wet flow is the most important feature for both ML models, followed by historical rainfall features for the purely data-driven ML model and hydrodynamic model outputs for the physics-leveraged ML model. Additionally, the achievable accuracy of both utilised ML models was highly sensitive to deviations in rainfall data, further limiting their reliability and trustworthiness.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 1","pages":"1-13"},"PeriodicalIF":2.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148457100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"A methodological review of AI/ML and evolutionary computation in hydrology and hydraulics: from ANN/SVM to deep learning, symbolic regression, and physics-informed models.","authors":"Maritza Liliana Arganis-Juárez, M Preciado","doi":"10.2166/wst.2026.304","DOIUrl":"10.2166/wst.2026.304","url":null,"abstract":"<p><p>This review synthesizes the methodological evolution of artificial intelligence and evolutionary computation in hydrology and hydraulics, from early machine learning (artificial neural networks, support vector machines, fuzzy systems, metaheuristics) to recent advances, including deep learning (long short-term memory, Convolutional Neural Network (CNN), Convolutional Long Short-Term Memory (ConvLSTM), graph neural networks), symbolic regression, and physics-informed modeling. Evidence is organized by application domain: model calibration, streamflow forecasting, hydrological regionalization, reservoir operation, and surrogate models for hydraulic simulation. We emphasize that algorithm selection should reflect hydrologic understanding, data constraints, and operational needs - not model complexity. Beyond cataloging techniques, the shift from purely data-driven prediction toward hybrid, physics-aware, uncertainty-quantified frameworks is described here. Case studies from Mexico illustrate end-to-end workflows, including reservoir operation using dynamic programming and genetic algorithms, guide-curve optimization in the Cutzamala System, stochastic dual dynamic programming applications in the Miguel Alemán-Cerro de Oro system, and flood mapping with U-Net using Sentinel-1 imagery. A public repository provides reproducible scripts and a structured reference database. This review concludes with a research agenda addressing extreme events, uncertainty, interpretable surrogates, and standardized multibasin evaluation.</p>","PeriodicalId":23653,"journal":{"name":"Water Science and Technology","volume":"94 1","pages":"166-179"},"PeriodicalIF":2.8,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148457049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}