The osmotic microbial fuel cell (OsMFC) is formed by combining forward osmosis (FO) and microbial fuel cells (MFC). Its excellent performance undoubtedly provided a new research direction for the application of FO and MFCs. However, the reverse solute flux (RSF) in FO also follows. RSF will cause a series of negative effects such as loss of draw solutions, decrease of water flux, and electricity generation. Therefore, inhibition of RSF is very necessary for the practical application of OsMFCs. Currently, there are much research and related reviews on RSF inhibition in FO but few studies on OsMFCs. To provide some new ideas for the inhibition of RSF in OsMFCs, we focused on three aspects: operating conditions, draw solutions, and FO membranes. Existing studies have demonstrated that some strategies are effective in OsMFC, including inhibitory effect of current generation, conventional inorganic draw solutions, membrane materials and orientation, and modified membranes. But there are many more strategies available. Using FO as a reference, strategies such as pressure-assisted osmosis and temperature control may be feasible and need to be investigated further. In the future, the inhibition or utilization of RSF can further improve the reactor performance and promote the early practical application of OsMFCs.

Water quality monitoring at the point of consumption by consumers can improve the understanding of the microbial risk of drinking water. In this study, drinking water samples were collected by citizen science participants according to their normal drinking sources and behaviors. Among six different sample types, tap water received the most attention per sampling frequency (39%) and weighted importance score, followed by drinking fountain (38%) and personal container (21%). Enumeration of Escherichia coli and the total coliform as indicator organisms showed consistent and good quality in water samples from tap water and drinking fountains but significantly higher detection frequencies (90 and 90%, respectively) and median concentrations (14 and 252 CFU/100 mL, respectively) in water samples from personal containers. Microbial community analysis based on 16S rRNA gene amplicon sequencing showed that the microbial communities in water samples from personal containers were less diverse than microbial communities in the other water types, the latter of which showed high similarity in the microbial composition and α and β diversity. Several genera that include species of opportunistic pathogens were detected across samples from drinking water sources, while higher total relative abundances of these genera were detected in water samples from personal containers than others.

The separation of photogenerated charges is vital for photocatalysis. Here, we report a wireless photoelectrochemical strategy for efficient charge separation on an optoelectronic synergy-driven nanoparticulate semiconductor. Using g-C3N4/Fe–TiO2 as model semiconductor nanoparticles, an advanced oxidation process (AOP) for water remediation was established with the activity and O2•– photogeneration quantum efficiency being significantly improved (i.e., 9.7 times compared to conventional photoelectrocatalysis and 5.9 times that of photocatalysis, respectively). More importantly, this strategy has a wide range of applications for the removal of different refractory organic pollutants with a strong tolerance for a supporting electrolyte. The extraordinary catalytic performance was attributed to a synergistic effect between photochemistry and electrochemistry on the particle surface, where numerous nanobipolar electrodes were generated under an electric field to trigger the reduction of electrogenerated O2 to form reactive oxygen species. This work provides a promising AOP strategy of a photoelectrochemical-driven nanoparticulate semiconductor for challenging water remediation.

There have been mounting concerns over microplastics as a vector of environmental xenobiotics recently. Adsorption plays a pivotal role in this process, which varies with the properties of xenobiotics, the characteristics of microplastics, and environmental conditions. The vast number of xenobiotics and the diversity of microplastics, as well as the continuous weathering of microplastics in the environment, make it unrealistic to measure the adsorption capacity and affinity of each combination of xenobiotics, microplastics, and environmental conditions in laboratory studies. Random Forest (RF) and Artificial Neural Network (ANN) algorithms were used to predict the adsorption affinity of xenobiotics on microplastics and elucidate the impact of environmental parameters. pH is responsible for a large variation in the results through its effect on the dissociation of ionizable xenobiotics and the surface charge of microplastics. The aging status of microplastics had a smaller but still significant impact on adsorption affinity, with pristine particles generally having a higher affinity. The results shed light on the potential alteration of the fate and impact of xenobiotics by microplastics. As more data become available in the future, the precision of machine learning (ML) models can be further improved. Overall, our study demonstrated the potential of ML in predicting the adsorption of a wide range of xenobiotics on microplastics.

In this study, four poly(diallyl dimethylammonium chloride) (PDDA) with different molecular weights are applied for forward osmosis concentration of high-salinity wastewater; meanwhile, the quantified effect of osmotic pressure and viscosity on the FO water flux is studied systematically. The 35 wt % PDDA (<100 kDa) solution could provide a water flux of 8.8 LMH with DI water as feed, and a water flux of 8.0 LMH with 15,400 ppm synthetic high-salinity wastewater as feed. Osmotic pressure plays a major and positive role in the FO water flux, while viscosity plays a secondary and negative role. Specifically, the FO water flux exhibited a variation of 115% using four PDDA draw solutions with the same viscosity and different osmotic pressures, while it showed a variation of 11.5% with the same osmotic pressure and different viscosities. The relationship of solute diffusion resistivity K and viscosity η was formularized for detailed discussion. The data of 28 polyelectrolyte solutions are summarized and demonstrate similar inference.

The (re)introduction of wood into rivers is becoming increasingly popular, but its impact on streambed biogeochemical cycling is still poorly understood. It could affect fundamental ecosystem processes through multiple, potentially interacting mechanisms and lead to cascading effects for ecosystem function and the delivery of associated (dis)services. Here, a microcosm study explored the impacts of instream wood on key biogeochemical functions for different streambed sediment types throughout a typical temperate climate temperature range. The effects on a suite of physiochemical characteristics and microbial metabolic activity (MMA) were measured, as well as on associated ecosystem services (nitrate removal rate) and dis-services (greenhouse gas [GHG] emissions). Streambed wood significantly increased MMA, a key ecosystem process that underpins stream biogeochemical cycling. This likely explained an associated increase in the removal rate of nitrate and the emission of some GHGs. This study demonstrates that instream wood is a fundamental driver of stream biogeochemical activity. Omitting streambed wood from mechanistic studies of streambed biogeochemical activity could reduce the representativeness of results to real systems, with consequences, for instance, for global GHG emission estimates. If such ulterior impacts of (re)introducing instream wood are not considered, decision-makers may fail to identify risks and opportunities of restoration programs.

The susceptibility of 19 representative per- and polyfluoroalkyl substances (PFAS) to direct photolysis and defluorination under far-UVC 222 nm irradiation was investigated. Enhanced photolysis occurred for perfluorocarboxylic acids (PFCAs), fluorotelomer unsaturated carboxylic acids (FTUCAs), and GenX, compared to that at conventional 254 nm irradiation on a similar fluence basis, while other PFAS showed minimal decay. For degradable PFAS, up to 81% of parent compound decay (photolysis rate constant (k222 nm) = 8.19–34.76 L·Einstein–1; quantum yield (Φ222 nm) = 0.031–0.158) and up to 31% of defluorination were achieved within 4 h, and the major transformation products were shorter-chain PFCAs. Solution pH, dissolved oxygen, carbonate, phosphate, chloride, and humic acids had mild impacts, while nitrate significantly affected PFAS photolysis/defluorination at 222 nm. Decarboxylation is a crucial step of photolytic decay. The slower degradation of short-chain PFCAs than long-chain ones is related to molar absorptivity and may also be influenced by chain-length dependent structural factors, such as differences in pKa, conformation, and perfluoroalkyl radical stability. Meanwhile, theoretical calculations indicated that the widely proposed HF elimination from the alcohol intermediate (CnF2n+1OH) of PFCA is an unlikely degradation pathway due to high activation barriers. These new findings are useful for further development of far-UVC technology for PFAS in water treatment.

For thousands of years, data allowed societies to first understand the connection between water quality and public health and later to refine water and waste management strategies. In this commentary, we look at the past, present, and future of 'big-impact' data in the water sector, from ancient water systems to Paris’ valorization of wastes, London’s tribulations with cholera, and modern environmental standards for the protection of public and environmental health. We continue the journey of water data with emerging applications in understanding our water resources, including blue-green city planning, understanding water use trends in remote areas, water resource monitoring, and wastewater epidemiology. We conclude with a foray into the future of the water sector, where proactively managing water resources to ensure equitable and resilient water access can be informed by remote sensing, satellite-based monitoring, and machine learning. By understanding how water data revolutionized our societies in the past, we aim to inspire the use of big water data to open possibilities for managing urban and environmental water in our future.

Conductometric titrations were used to measure sulfate concentrations in ground and surface water samples taken from land reclaimed after open-air coal mining. Sulfate concentrations ranged from 460 mg/L in surface water upstream of the former coal mine’s location to almost 3500 mg/L in groundwater sampled at the spoil site. Data from the titration measurements were benchmarked against EPA-approved ion chromatography (IC) measurements and results agreed to within ±3.6% (averaged over 36 samples) with a range of +10.4 and −11.3%. To test the generality of conductometric titration as a method for measuring dissolved constituents in environmental aquatic systems, additional measurements testing for chloride were performed with surface water samples collected from four different sites in south central and southwest Montana. Chloride concentrations ranged from 2.2 to 12 ppm. Based on measurements with control samples prepared in the laboratory, the environmental sample measurements are believed to be accurate to within ±6.4%. These conductometric titration studies highlight the technique’s simplicity, accuracy, cost effectiveness, and potential to produce rapid results. Additional analyses suggest that even simpler, non-species-specific conductivity data can provide an on-site, rapid assessment of sulfate levels in ground and surface water when historical speciation data are available.

This article is part of the Water Challenges and Solution Opportunities in South Asia, a Rapidly Developing Region of the World special issue. The geographical location, climate change, rising population, and unplanned urbanization simultaneously probe a considerable water challenge in South Asia. The discharge of heavy metals such as chromium, manganese, lead, and mercury from industries, the release of organic compounds from wastewater treatment plants, the use of dyes in the textile industry, the disposal of pharmaceutical waste by pharmaceutical companies, and the seepage of pesticides, herbicides, insecticides, and fertilizers from agricultural land all contribute to water pollution. It then propagates via irrigation, drinking, and domestic usage, adversely affecting humans and the aquatic ecosystem. Apart from scientific advancements in wastewater treatment technologies, another aspect of remediation comprising the spatiotemporal analysis of water pollution and originating water crisis is less explored. So, it becomes crucial to integrate water resources, the origin of water pollution by natural (e.g., flooding) and artificial (e.g., industrialization) means, and the role of researchers and society in effectively tackling the water challenges. We are pleased to launch “Water Challenges and Solution Opportunities in South Asia, a Rapidly Developing Region of the World “ as a special issue in ACS ES&T Water. There are 22 publications, comprising 14 research articles, 2 viewpoint/perspective, and 6 review papers. The topics covered can be broadly categorized into two major aspects: (1) aquatic ecosystem surveys and (2) strategies to treat emerging water pollutants. The aquatic ecosystem surveys across different parts of South Asia are essential to include in this special issue. They will help us understand the location-dependent reasons for water pollution and their effects on human beings and aquatic ecosystems. These papers include case studies on (a) spatiotemporal groundwater analysis, recharging mechanisms, and evaluation for drinking and irrigation purposes, (b) impacts on groundwater intermixing with seawater in coastal regions, (c) anthropogenic activities affecting water quality, and (d) correlating climate change impacts using remote sensing with public health management. The impacts of spatial and depth-dependent determinants on groundwater level (GWL) projections are considered and correlated with the agriculturally intensive regions of South Asia. These considerations may be implemented in various regions, bringing attention to the relevance of spatiotemporal to multidepth aspects in GWL forecasting. Apart from GWL projections, Karangoda and Nanayakkara explored georeferencing and spatial interpolation techniques to determine the groundwater quality in the Ratnapura District, Sri Lanka. The study provides the spatial distribution of hardness, pH, and electrical conductivity, along with their causes governed by the climate and geological conditions. Also considered is the release of heavy metals from rocks, such as quaternary alluvial sediments, which has significantly damaged the water quality. The arsenic and manganese inclusions in the groundwater are studied by Mueller et al. and Rahman et al., respectively. Furthermore, Rajendran et al. provided insights about treating the formation water from hydrocarbon reservoirs as it pollutes the groundwater, surface water, and soil. Nepal’s federal, provincial, and municipal administrations are all described by Shrestha et al. in their efforts to recognize the threats posed by climate change to water, sanitation, and hygiene (WASH) infrastructure. Since Bangladesh uses both surface and groundwater for agriculture and drinking, Gulfam-E-Jannat et al. deduced that the contamination of these resources is devastating. They discussed future problems and solutions to treat industrial wastewater. Water shortages in Sri Lanka are examined, and its root causes determined in research by Chandrasekara et al. As water shortages increase in Sri Lanka, this research examines the measures to counteract the problem. Indika et al. studied the water supply possibilities to ensure long-term viability in Sri Lanka’s North Central Province. They suggested that reverse osmosis technology pretreated with softening and activated carbon would be the most effective way to deal with very salty groundwater in many parts of North Central Province. The second category of papers focuses on sustainable strategies to treat emerging water pollutants and provide a path for large-scale water treatment. Examples of pollutants studied include Indigo carmine, benzotriazoles, benzothiazoles, benzophenones, p-phenylenediamines, manganese, chromium, and arsenic, alongside many others. Samriti et al. discuss the scientific ways to utilize nanomaterials and develop methods to treat wastewater. These include photocatalytic/adsorptive removal, disinfection, tracing, and sensing. For more emphasis on sustainable approaches, Mao et al. developed manganese-oxidizing bacteria to treat wastewater from acid mines using continuous stirred tank bioreactors. Different materials, including CdS-doped glucose-derived carbon nanoflakes photocatalysts and Ti/RuO2-stainless steel, have been explored using photodegradation and ultrasound enhanced electro-Fenton mineralization, respectively. As guest editors in this special issue of ACS ES&T Water, we sincerely acknowledge all the authors, reviewers, and associate editors who helped present an informed and intuitive picture of South Asia’s water concerns to a broader and more general audience. Combating water contamination, raising public awareness about the alarming situation, and finding practical solutions are crucial in the current scenario. Different infrastructure, financial, and policy challenges must be carefully addressed. This special issue builds a foundation to state and solve these critical problems. Dr. Raju Kumar Gupta is a Professor in the Department of Chemical Engineering, Indian Institute of Technology Kanpur, India. Dr. Gupta has made important contributions to the area of sustainable materials, green synthesis, nanostructured materials for wastewater treatment and energy storage applications. His current research interests are photocatalysis for water remediation and CO2 conversion to fuels, perovskite solar cells, and energy storage devices based on batteries. Dr. Gupta has been recipient of several fellowships and awards for his outstanding career in academic and research fields e.g. Distinguished Young Alumnus Awards 2021 and Fellowship of the Royal Society of Chemistry 2022. He has authored more than 115 research articles in international journals, 4 patents, 3 edited books, and 18 book chapters and guest edited special issues for several international journals, and his work has been cited more than 8500 times. Dr. Gupta is an editorial board member of several international journals, as well as a member of scientific bodies e.g. associate editor for Solar Energy; editorial board member for Scientific Reports, Journal of Polymer Science and Current Opinion in Green and Sustainable Chemistry. Dr.-Ing. Fazlullah Akhtar serves as a Senior Researcher at the Center for Development Research (ZEF) of the University of Bonn, Germany. He specializes in the field of water resources management, with a specific focus on the challenges faced in developing countries. Dr. Shameen Jinadasa is Professor in Civil Engineering at the Department of Civil Engineering, University of Peradeniya, Sri Lanka. He is an award-winning water engineer with international experience. Dr Jinadasa has coordinated multinational and multisectoral research teams with experts from Singapore, Japan, Australia, the United States, New Zealand, and Sri Lanka with a range of disciplinary backgrounds such as agriculture, social science, economics, water resources management, and wastewater management to address complex water-related problems. His work has received recognition in Japan, Singapore, China, and the United States, where he has held prestigious fellowships and grants. Dr Jinadasa was educated at the University of Peradeniya, National University of Singapore, and Saitama University Japan. Dr. Jinadasa has published extensively with over 100 publications and is currently engaged in research fellowships with the United States and China. Shukra Raj Paudel is an Associate Professor of Environmental Engineering at the Department of Civil Engineering, Pulchowk Campus, Institute of Engineering, Tribhuvan University, Nepal, working in the area of water quality and treatment technologies. He is actively involved in teaching and research in environmental engineering at the university. He is a member of editorial advisory board in the journal Renewable Energy Focus and serves as editor and associate editor of domestic journals. M. Feisal Rahman is a Post Doctoral Research Associate in the Department of Geography and Environmental Sciences at Northumbria University, UK. His current work focuses on enhancing resilience in the Asian Deltas and ensuring trans-disciplinarity and coproduction in sustainable development research. He received his Ph.D. from the University of Waterloo, Canada, a Master’s degree from the University of Western Ontario, Canada, and a Bachelor’s degree from the Bangladesh University of Engineering and Technology, Dhaka, Bangladesh. R.K.G. acknowledges financial assistance from the Department of Science and Technology (DST), India, through Grant No. DST/TM/WTI/2K16/23(G), and from Science and Engineering Research Board, Department of Science & Technology, Government of India (Project no. CRG/2021/007464). This article has not yet been cited by other publications. Dr. Raju Kumar Gupta is a Professor in the Department of Chemical Engineering, Indian Institute of Technology Kanpur, India. Dr. Gupta has made important contributions to the area of sustainable materials, green synthesis, nanostructured materials for wastewater treatment and energy storage applications. His current research interests are photocatalysis for water remediation and CO2 conversion to fuels, perovskite solar cells, and energy storage devices based on batteries. Dr. Gupta has been recipient of several fellowships and awards for his outstanding career in academic and research fields e.g. Distinguished Young Alumnus Awards 2021 and Fellowship of the Royal Society of Chemistry 2022. He has authored more than 115 research articles in international journals, 4 patents, 3 edited books, and 18 book chapters and guest edited special issues for several international journals, and his work has been cited more than 8500 times. Dr. Gupta is an editorial board member of several international journals, as well as a member of scientific bodies e.g. associate editor for Solar Energy; editorial board member for Scientific Reports, Journal of Polymer Science and Current Opinion in Green and Sustainable Chemistry. Dr.-Ing. Fazlullah Akhtar serves as a Senior Researcher at the Center for Development Research (ZEF) of the University of Bonn, Germany. He specializes in the field of water resources management, with a specific focus on the challenges faced in developing countries. Dr. Shameen Jinadasa is Professor in Civil Engineering at the Department of Civil Engineering, University of Peradeniya, Sri Lanka. He is an award-winning water engineer with international experience. Dr Jinadasa has coordinated multinational and multisectoral research teams with experts from Singapore, Japan, Australia, the United States, New Zealand, and Sri Lanka with a range of disciplinary backgrounds such as agriculture, social science, economics, water resources management, and wastewater management to address complex water-related problems. His work has received recognition in Japan, Singapore, China, and the United States, where he has held prestigious fellowships and grants. Dr Jinadasa was educated at the University of Peradeniya, National University of Singapore, and Saitama University Japan. Dr. Jinadasa has published extensively with over 100 publications and is currently engaged in research fellowships with the United States and China. Shukra Raj Paudel is an Associate Professor of Environmental Engineering at the Department of Civil Engineering, Pulchowk Campus, Institute of Engineering, Tribhuvan University, Nepal, working in the area of water quality and treatment technologies. He is actively involved in teaching and research in environmental engineering at the university. He is a member of editorial advisory board in the journal Renewable Energy Focus and serves as editor and associate editor of domestic journals. M. Feisal Rahman is a Post Doctoral Research Associate in the Department of Geography and Environmental Sciences at Northumbria University, UK. His current work focuses on enhancing resilience in the Asian Deltas and ensuring trans-disciplinarity and coproduction in sustainable development research. He received his Ph.D. from the University of Waterloo, Canada, a Master’s degree from the University of Western Ontario, Canada, and a Bachelor’s degree from the Bangladesh University of Engineering and Technology, Dhaka, Bangladesh.

Carbocatalyst/persulfate is a green, highly oxidative system for decontaminating refractory aqueous organic pollutants. Exploring facile routes to tune the catalytic activity and selectivity (persulfate activation pathway) of carbonaceous materials toward persulfate activation is very appealing, which offers a platform for selective oxidation of organic pollutants. In this work, we showed that the interfacial electric field (IEF) is a facile approach to alter the catalytic activity and selectivity of carbon/persulfate systems via the field-dipole effect. To study the IEF effects, a carbon electrode fabricated from powdery carbons was assembled into an asymmetric quasi-capacitive deionization cell, and positive/negative voltages were applied. Through integrated experimental and theoretical investigations, we found that the bond structures of both persulfate anion and its transition state were changed under IEF, while the scenarios in the cases of positive and negative IEF were distinct. Positive IEF induces/reinforces the nonradical oxidation pathway based on carbon-persulfate complexes in the carbon/persulfate system, while different persulfate activation pathways (nonradical carbon-persulfate complexes and/or free radicals) can be induced under negative IEF depending on the bonding strength between persulfate and the carbocatalyst. Our results offer a feasible approach to tune the redox potentials of carbon-based advanced oxidation systems toward selective oxidation of organic pollutants.

Biosurfactants are promising alternatives to chemical dispersants for combating marine oil spills; however, the impacts of biosurfactants on microbial community composition and oil biodegradation activities remain largely unknown. Here, we conducted a time-course microcosm experiment mimicking oil spill scenarios with surface seawater from the North Sea, amended with either the biosurfactant rhamnolipid or a dispersant (Corexit 9500 or Slickgone NS). Radioactive tracer assays to track hexadecane and naphthalene oxidation as well as bacterial production revealed the highest hydrocarbon oxidation rates and general microbial activities in the rhamnolipid-amended oil microcosms, followed by oil microcosms with Slickgone and Corexit. Impacts on the microbial community composition differed among treatments, and growth of oil-degrading Colwellia was stimulated remarkably in Corexit-amended oil and oil-only microcosms, while potential oil-degrading Oleispira were highly enriched in the presence of oil in combination with rhamnolipid or Slickgone. Furthermore, increased abundances of Colwellia and Oleispira, and stimulated bacterial production in microcosms with only rhamnolipid, Corexit, or Slickgone, indicated their involvement in biosurfactant/dispersant biodegradation. Our findings highlight varying microbial impacts resulting from rhamnolipid and chemical dispersants and suggest great promise for the application of biosurfactants in future marine oil spills.

Iodine (I2) in the form of iodide ions (I–) is an essential chemical element in the human body. Iodine is a nonmetal that belongs to the VIIA group (halogens) in the periodic table. Over the last couple of centuries, the exponential growth of human society triggered by industrialization coincided with the use of iodine in a wide variety of applications, including chemical and biological processes. However, through these processes, the excess amount of iodine eventually ends up contaminating soil, underground water, and freshwater sources, which results in adverse effects. It enters the food chain and interferes with biological processes with serious physiological consequences in all living organisms, including humans. Existing removal techniques utilize different materials such as metal–organic frameworks, layered double hydroxides, ion-exchange resins, silver, polymers, bismuth, carbon, soil, MXenes, and magnetic-based materials. From our literature survey, it was clear that absorption techniques are the most frequently experimented with. In this Review, we have summarized current advancements in the removal of iodine and iodide from human-made contaminated aqueous waste.

Harmful algal blooms have become a global environmental problem. Persulfate-based advanced oxidation processes (PS-AOPs) are a good method for controlling the algal bloom emergency. However, the practical application of PS-AOPs is hindered by the low efficiency and difficult recovery of the powdered catalysts in actual water. To address this challenge, a novel floatable 3D sponge@SBC composite (sponge@SBC1-300) was synthesized using biochar through a simple coating process. The sponge@SBC1-300 showed excellent mechanical stability and catalytic performance in PS-AOPs, achieving 97.7% removal of Microcystis aeruginosa in 250 mins. Good stability and repeatability with a 90.1% removal efficiency after four reuse times were observed. In addition, in the actual river and lake water samples, M. aeruginosa can be effectively inactivated (87.9%). Dual mechanisms, including free-radical (SO4•–, •OH, and •O2–) and nonradical (1O2 and electron transfer) pathways, were found to participate in M. aeruginosa inactivation. Based on the observations of changing cellular morphologies, membrane permeability, and antioxidant system of M. aeruginosa, it was suggested that the generated reactive oxygen species could inactivate algae cells by attacking cell membranes and damaging their antioxidant systems.

Phytoplankton are used worldwide to monitor the environmental status of aquatic systems. Long-time series of microscopy-analyzed phytoplankton are available from many monitoring stations. The microscopy method is, however, time-consuming and has shortcomings. DNA metabarcoding has been suggested as an alternative method, but the consistency between different methods needs further investigation. We performed a comparative study of microscopy and metabarcoding analyzing micro- and nanophytoplankton. For metabarcoding, 25–1000 mL of seawater was filtered, DNA extracted, and the 18S and 16S rRNA gene amplicons sequenced. For microscopy, based on the Utermöhl method, we evaluated the use of three metrics: abundance, biovolume, and carbon biomass. At the genus, species, and unidentified taxa levels, metabarcoding generally showed higher taxonomic diversity than microscopy, and diversity was already captured at the lowest filtration volume tested, 25 mL. Metabarcoding and microscopy displayed relatively similar distribution patterns at the group level. The results showed that the relative abundances of the 18S rRNA amplicon at the group level best fitted the microscopy carbon biomass metric. The results are promising for implementing DNA metabarcoding as a complement to microscopy in phytoplankton monitoring, especially if databases were improved and group-level indices could be applied to classify the environmental state of water bodies.

Enzyme-mimetic metal-based catalysts have received extensive attention for the efficient catalytic applications. These catalysts can be adapted to complex environmental circumstances, thus becoming one of the effective ways to deal with refractory pollutants. In previous research, the K+-intercalated FeOCl (KxFeOCl) catalyst can produce Fe(IV)═O intermediate species through heterocleavage of H2O2 in a similar way as natural peroxidases. In this study, the detailed kinetics and surface reaction mechanisms of KxFeOCl were comprehensively investigated using 2-methoxyphenol (2-MeOP) as the model contaminant and at pH 7. 2-MeOP molecules are oxidized to organic radicals, which further oxidize 2-MeOP for direct radical–radical coupling. Based on the kinetics, the Langmuir–Hinshelwood model was used to describe the oxidative coupling of 2-MeOP on the KxFeOCl/H2O2 system. The competitive adsorption of H2O2 and downstream catalase activity of H2O2 decomposition were also proposed. The substrate oxidation rate of high-valent iron species reached 9.25 × 105 mM–1 min–1. These results clarified the intrinsic kinetic principle and interfacial reaction mechanism of 2-MeOP oxidative coupling catalyzed by KxFeOCl, offering valuable insights for optimizing reaction performance and scaling up the process.

Mechanistic models can provide predictive insight into the design and optimization of engineered biological systems, but the kinetic parameters in these models need to be frequently calibrated and uniquely identified. This limitation can be addressed by hybrid modeling that integrates mechanistic models with data-driven approaches. Herein, we developed a hybrid modeling strategy using bioelectrochemical systems as a platform system. The data-driven component consisted of artificial neural networks (ANNs) trained with mechanistically derived kinetic parameters as outputs to compute error signals. The hybrid model was built using 148 samples from the literature. After 10-fold cross-validation, the model was tested with another 28 samples. Internal resistance was accurately predicted with a relative root-mean-square error (RMSE) of 3.9%. Microbial kinetic parameters were predicted using the data-driven component and fed into the mechanistic component to simulate the system performance. The R2 values between predicted and observed organic removal and current for systems fed with a simple substrate were 0.90 and 0.94, respectively, significantly higher than those obtained from the stand-alone data-driven model (0.51 and 0) and mechanistic model (0.07 and 0.15). This strategy can potentially be applied to engineered biological systems for in silico system design and optimization.

Identifying and quantifying algal genera in images are crucial for understanding their ecological impact. Algal data are often imbalanced, limiting detection model accuracy. This paper presents a novel data augmentation method using StyleGAN2-ADA to enhance algal image instance segmentation. StyleGAN2-ADA generates artificial single-algal images to address data scarcity and imbalance. We train a Cascaded Mask R-CNN with Swin Transformer on a combined data set of real and artificial multigenera algal images and evaluate performance using the COCO mAP metric. The approach improves bounding box detection performance by 17.9% on all genera and 32.1% on rare genera compared with the baseline model. Additionally, 50% more artificial data yield significant enhancements without excessive artificial data use. The GAN-based augmentation technique shows a performance improvement in both Swin-Tiny and ResNet-50 backbone models, suggesting adaptability for various machine learning models. The increased mAP leads to the accurate identification of harmful algae genera, allowing for better prevention and mitigation. This method offers a superior data augmentation solution for accurate algal instance segmentation and can benefit applications challenged by imbalanced and scarce data.

Figure 1. Seventeen chemically similar rare earth elements and their distribution by country (Canada, Greenland, Tanzania, and South Africa are included in “Other”) and end use. (7) Qieyuan Gao is now a Ph.D. student in the research division “Process Engineering for Sustainable Systems” within the department of Chemical Engineering at KU Leuven, starting his Ph.D. research in 2020. He has long been engaged in the research of industrial water treatment and advanced separation technology. He received a Master’s in engineering from the China University of Mining and Technology in 2020. To date, Qieyuan Gao has published 14 peer-reviewed journal articles. He is also a reviewer for internationally renowned journals Separation and Purification Technology, Journal of Colloid and Interface Science, Fuel, ACS ES&T Water, etc. He is also a member of the European Membrane Society (EMS) (from 2022). In addition, he was funded by the China Scholarship Council (CSC) to go to KU Leuven for doctoral research. Bart Van der Bruggen is a professor at the University of Leuven (KU Leuven) in Belgium, where he leads a group of 30 Ph.D. students in the research division “Process Engineering for Sustainable Systems” within the Department of Chemical Engineering. His expertise is in separation technologies for sustainable processes, with an emphasis on membrane science and technology. He has authored more than 700 publications in international journals (current h-factor: 93; >36 000 citations) and 30 book chapters. He has been the scientific promoter of 65 Ph.D. theses. He was the President of the European Membrane Society (EMS) from 2013 to 2017 and is the Founding President of the World Association of Membrane Societies (2017–2020). Since 2014, he has also been an Extraordinary Professor in Tshwane University of Technology (South Africa). He is Editor-in-Chief of Separation and Purification Technology (Q1, IF 9.1), Executive Editor of the Journal of Chemical Technology and Biotechnology (IF 3.7), Section Editor of Heliyon, and Associate Editor of Process Safety and Environmental Protection. Q.G. acknowledges the support provided by the China Scholarship Council (CSC) of the Ministry of Education, P. R. China (CSC 202006420004). This article references 10 other publications. This article has not yet been cited by other publications. Figure 1. Seventeen chemically similar rare earth elements and their distribution by country (Canada, Greenland, Tanzania, and South Africa are included in “Other”) and end use. (7) Qieyuan Gao is now a Ph.D. student in the research division “Process Engineering for Sustainable Systems” within the department of Chemical Engineering at KU Leuven, starting his Ph.D. research in 2020. He has long been engaged in the research of industrial water treatment and advanced separation technology. He received a Master’s in engineering from the China University of Mining and Technology in 2020. To date, Qieyuan Gao has published 14 peer-reviewed journal articles. He is also a reviewer for internationally renowned journals Separation and Purification Technology, Journal of Colloid and Interface Science, Fuel, ACS ES&T Water, etc. He is also a member of the European Membrane Society (EMS) (from 2022). In addition, he was funded by the China Scholarship Council (CSC) to go to KU Leuven for doctoral research. Bart Van der Bruggen is a professor at the University of Leuven (KU Leuven) in Belgium, where he leads a group of 30 Ph.D. students in the research division “Process Engineering for Sustainable Systems” within the Department of Chemical Engineering. His expertise is in separation technologies for sustainable processes, with an emphasis on membrane science and technology. He has authored more than 700 publications in international journals (current h-factor: 93; >36 000 citations) and 30 book chapters. He has been the scientific promoter of 65 Ph.D. theses. He was the President of the European Membrane Society (EMS) from 2013 to 2017 and is the Founding President of the World Association of Membrane Societies (2017–2020). Since 2014, he has also been an Extraordinary Professor in Tshwane University of Technology (South Africa). He is Editor-in-Chief of Separation and Purification Technology (Q1, IF 9.1), Executive Editor of the Journal of Chemical Technology and Biotechnology (IF 3.7), Section Editor of Heliyon, and Associate Editor of Process Safety and Environmental Protection. This article references 10 other publications.

Climate change hazards, including increased temperatures, drought, sea level rise, extreme precipitation, wildfires, and changes in freeze–thaw cycles, are expected to degrade drinking water utility system infrastructure and decrease the reliability of water provision. To assess how drinking water utility manager perceptions of these risks affect utility planning, 60 semistructured interviews were conducted with utilities of various sizes, source water supplies, and United States geographical regions. This study analyzes these interviews (1) to evaluate which climate hazards are of primary concern to drinking water managers, (2) to develop a mental model framework for assessing utility-level understanding of climate change risks to system reliability, and (3) to examine the status of current water utility adaptation planning. The results show that concern and awareness of climate hazard risks vary geographically and are grounded in historical exposure; some participants do not believe climate change will influence their system’s overall reliability. When considering climate change risks, utility managers tend to focus on effects to water supply and infrastructure, as opposed to changes in operations and maintenance, water quality, or business functions. Most surveyed utilities do not have comprehensive climate adaptation plans despite federal and professional recommendations. The range of beliefs and actions concerning climate adaptation planning indicates that utilities need directed guidance, and policymakers should consider including climate hazards and projections as part of required utility risk and resilience assessments.