Pesticide pollution of surface water is a global threat to drinking water safety. The need for improved drinking water treatment methods is discussed by using Brazil as a case study. Brazil’s agriculture is intensive, and pesticide consumption is high, while current drinking water treatment methods are inadequate for effectively removing pesticides. Available data on surface water contamination in Brazil show widespread occurrence of pesticides in natural waters, thereby putting pressure on the water treatment system and threatening the quality and safety of drinking water. Pesticide concentrations in drinking water frequently exceeded the maximum permissible concentrations if EU regulations (0.1 μg/L) were applied, highlighting the need for improvements in drinking water treatment. (Advanced) drinking water treatment for the removal of pesticides has been intensely researched over the past decade. However, challenges such as high cost and energy intensity, as well as the production of hazardous byproducts, must be assessed critically. Safely managed drinking water is crucial to the sustainable development of low- and middle-income countries and can be achieved only through appropriate technology. Engineered biofiltration has been put forward as a sustainable alternative to conventional and advanced drinking water treatment. This review highlights the promising potential of engineered biofiltration and its associated challenges.

Building water systems are associated with variable water age and temperatures, causing water quality concerns. Legionella spp., nontuberculous mycobacteria (NTM), and Pseudomonas spp. are known to inhabit and grow in these systems for which building-level interventions are often required to reduce their concentrations and detections. Other contaminants such as metals and disinfection byproducts (DBPs) are also health concerns. Interventions are typically flushing, temperature manipulation, responsive facility-level interventions (e.g., chemical disinfection and heat shock), or point-of-use devices. A systematic literature review was conducted to summarize interventions targeting pathogen control, and subsequent meta-analysis quantified their respective log reduction values (LRVs). Across the studies (n = 45), Legionella spp. was the primary target (n = 45), and studies varied from laboratory benchtops/pipe racks to hospitals and residential or commercial buildings. Additional measurements and LRVs for heavy metals (e.g., copper, lead, and iron) and DBPs such as trihalomethanes (THMs) were evaluated. The findings pointed to the importance of contextual conditions and incoming water quality in playing a role in both pathogen occurrence and intervention effectiveness. Common interventions such as recommissioning flushing and increased temperature should be further examined for their impacts on pathogens besides Legionella spp. and their contribution to biofilm sloughing and pathogen regrowth. Trade-offs, such as increased metal leaching in parallel with pathogen inactivation, should be examined in context with intervention and building water quality conditions.

Global industrialization and urbanization have led to a surge in wastewater production, with the industrial sector accounting for 22% of global water consumption. Regrettably, up to 80% of treated industrial effluent is discharged directly into water bodies, posing severe environmental contamination risks. This underscores the critical necessity for sustainable wastewater management. Among the industries that consume large amounts of water is the automotive. Automotive wastewater, primarily from emulsion and paint processes, contains toxic substances such as paints, metals, and organic compounds. Additionally, dyestuffs and paints contribute to environmental challenges due to their toxicity and slow degradation. This review explores different wastewater treatment approaches, including physicochemical, biological, and membrane technologies, to tackle the complexity of automotive wastewater. Physico-chemical methods effectively remove pollutants but generate sludge. Biological treatments face challenges related to heavy metals and nonbiodegradable compounds. Membrane separation, particularly forward osmosis, shows potential as an energy-efficient solution. The review addresses challenges in automotive wastewater treatment, like sludge management and heavy metal inhibition. Advanced approaches, such as enzyme-based treatments and natural materials like banana peels, and zeolites natural and synthetic are discussed for their potential to enhance efficiency. This article offers insights into the current state of automotive wastewater treatment, emphasizing the need for green solutions to protect public health and the environment.

Coagulation is widely used in water treatment, generating large volumes of water treatment residual (WTR), most of which is aluminum salt-based water treatment residual (Al-WTR). This waste is environmentally and financially costly to manage. Al-WTR, however, can be upcycled into value-added products such as ceramsite, a porous material that can be used for adsorption or other beneficial purposes. Here, we review the fabrication processes for transforming Al-WTR into ceramsite, the strategies for enhancing its performance, and its potential environmental applications. Ceramsite has exhibited potential as an adsorbent in removing pollutants such as phosphorus and heavy metals as well as being a biofilm-supporting medium. Moreover, ceramsite has shown the effective removal of emerging pollutants from water matrices. Therefore, ceramsite represents a promising strategy for valorizing Al-WTR. Further investigations are required to improve the ceramsite performance and assess its applicability in environmental engineering. Furthermore, we also discuss the current challenges and barriers associated with the application of the Al-WTR-derived ceramsite and possible mitigation strategies. This Review aims to stimulate further research and development in sustainable WTR management, thereby contributing to the development of a circular economy in the water treatment sector.

Although free amino acids (FAAs) are known as an important precursor of nitrogenous disinfection byproducts (N-DBPs), their levels and composition in source water as well as their contributions to drinking water N-DBPs are not clear. This review provides a summary of occurrence and compositions of FAAs in different water sources as well as their molar yields and contributions to N-DBPs formation. Moreover, the impacts of advanced oxidation processes (AOPs) on N-DBPs formation are also summarized. The average concentrations of FAAs in rivers, lakes, and reservoirs were 439, 402, and 370 nM (about 56.2, 51.5, and 47.4 μg/L), in which cysteine, ornithine, alanine, glutamic acid, and serine were dominant among individual FAAs, with an average level of 25.6, 8.6, 6.2, 6.0, and 5.3 μg/L, respectively. During the chlorination process, the molar yields of FAA for dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), dichloroacetamide (DCAM), and trichloronitromethane (TCNM) were not detectable (ND)-7.1, ND-3.55, ND-0.93, and ND-1.99 μmol/mmol, respectively, contributing 7.0%, 11.9%, 0.3%, and 10.3%, on average, to drinking water N-DBPs. During chloramination, the molar yields of FAA fall within ND-5.55, ND-3.55, 0.4-176, and ND-1.52 μmol/mmol, constituting on average 5.3%, 18.4%, 0.8%, and 3.0% of DBPs’ formation in drinking water. The information provided may help enrich the knowledge of FAAs and gain insights toward the importance of FAAs in forming N-DBPs.

In the face of escalating climate change impacts, Southeast Asia is witnessing a growing urgency to fortify regional cities against extreme temperatures and the exacerbating effects of El Niño events. This work delves into the role of urban water technologies in bolstering heat-resilient infrastructure across the region. This work also assesses urban water technologies that can contribute to the development of heat-resilient infrastructure in urban areas. This involves examining innovative approaches that can help mitigate the impacts of extreme temperatures on water infrastructure and enhance its resilience to climate change. They include green infrastructure, decentralized water systems, and advanced cooling technologies that have the potential to improve the resilience of urban water infrastructure to heat stress and extreme temperatures. Through empirical studies, this study underscores the imperative for proactive measures to enhance urban resilience in the region. The implications of this work offer practical insights for policymakers, urban planners, and stakeholders to bolster climate resilience in the region, emphasizing the role of water technologies in mitigating risks and enhancing adaptive capacity. By integrating urban technologies such as advanced cooling systems and green infrastructure, cities in the southeast Asia region not only can mitigate heat-related risks but also foster sustainable development pathways.

Climate change poses challenges to infrastructure resilience in Southeast Asia’s flood-prone regions. This study identifies and evaluates strategies for enhancing infrastructure resilience through wastewater treatment plants (WWTPs) in Singapore, Malaysia, Thailand, and Indonesia. Using a mixed-method approach, we analyzed the case studies and conducted quantitative assessments of flood mitigation efforts. Data were collected (2021–2024) through site visits, interviews with key stakeholders, and analysis of historical flood and infrastructure performance data. Data analysis involved statistical methods for assessing their effectiveness and comparative analyses across them. Singapore reduced flood-prone areas by 30% using integrated WWTP technologies with drainage systems, while Malaysia developed resilient infrastructure networks with WWTPs designed to withstand extreme weather, preventing 85% of contamination cases. Thailand combined green and blue infrastructure with WWTPs, decreasing flood vulnerability by 25%. Indonesia invested in decentralized WWTPs in urban areas, increasing infrastructure resilience by 40%. Nature-based solutions, such as ecological restoration, reduce flooding impacts by 20%. The implications for policymakers and practitioners include the need to integrate advanced technologies and nature-based solutions to bolster infrastructure resilience and mitigate flooding risks. This study offers insights into developing effective climate change adaptation strategies in flood-vulnerable regions, emphasizing the critical role of WWTPs in enhancing infrastructure resilience.

As stresses on groundwater resources increase due to growing population and climate change, water litigation, such as the recently decided Mississippi (MS) vs Tennessee (TN) lawsuit, will become more common. In the United States, lawsuits between states can be heard only by the Supreme Court of the United States (SCOTUS). These lawsuits are expensive and lengthy, often requiring highly specialized technical expertise. In the MS vs TN case, the Court unanimously held that an interstate aquifer is subject to equitable apportionment. Although this appears to be a sound resolution, a careful examination of the SCOTUS hearing transcript revealed that the Justices had several egregious misconceptions about the groundwater system. These misconceptions arose in part due to the failure of technical experts to communicate groundwater concepts in understandable terms and in part due to the Justices’ lack of expertise in groundwater science. To address these issues, we first explore methods for improving scientific communication in courtrooms. Second, we propose ideas for reforming the legal system and provide compelling arguments for using the lower courts to hear such cases. We also explore the possibility of creating specialized federal water courts to resolve water disputes.

The three inorganic chloramines play central roles in aqueous chloramination processes. Mechanisms involving these species are required to obey the principle of detailed balancing, but very few published examples meet this requirement. There are at least 77 publications with chloramine mechanisms that violate the principle of detailed balancing. In this work, the violations are summarized, a set of reaction equilibrium constants and rate constants is proposed that should facilitate the development of acceptable mechanisms, and solutions to the published errors are proposed.

This study investigates the longitudinal and temporal trends of atrazine, a persistent herbicide, in the Mae Sa catchment in northern Thailand. Concentrations of atrazine determined from targeted analysis were elevated during the wet season, and great variability was observed in relation to individual storm runoff hydrographs. When compared to regulatory limits, the observed atrazine concentrations in Mae Sa were generally below environmental thresholds of concern. However, greater risk may occur in other tributary systems feeding the Ping River, where some concentrations exceeding 2000 ng/L were observed, although they were not sustained for extended periods of time. Additionally, nontargeted screening identified 16 other agrochemicals with known potential environmental risks or associated toxicity. Despite the minor risk posed by atrazine alone, the research highlights the intricate interplay of agricultural practices, diverse pesticide application, and hydroclimatic factors in influencing pesticide dynamics. In the broader context, this study underscores the challenge of estimating risks arising from pesticide mixtures while using a combination of targeted analysis, nontargeted screening, in silico prediction models, and in vitro bioassays. Collectively, we find evidence of the presence of more than 100 pesticides in the catchment since dedicated work began there more than a decade ago.

Managing contamination by urban storm runoff is challenging because of numerous contaminant sources, the first flush phenomenon, and the fast drainage of stormwater by storm sewers. This paper presents the results of laboratory batch, column, and flow-through tests involving a novel in situ chemical oxidation scheme that combines oxidation and slow-release systems to reduce organic pollutants in urban storm runoff. In batch tests, the persulfate/iron system yielded the best overall removal efficiencies for benzene, toluene, ethylbenzene, xylene, and naphthalene, although the removal rates rapidly decreased after 2 to 3 min due to oxidation of ferrous iron in the solution. Slow-release persulfate (SRP), slow-release hydrogen peroxide (SRH), and slow-release Fe²⁺ (SRI) were created by dispersing salts in paraffin wax matrices in a cylindrical mold. Results of column tests indicated that the slow-release forms could release oxidants and Fe²⁺ in a controlled and continuing manner, and the release rates are constrained by the solubility of the dispersed salts and the mixing ratios of the salts and matrices. In the flow-through remedial tests, 89% of naphthalene, ethylbenzene, and xylene, 83% of toluene, and 73% of benzene were removed within 20 min when SRP and SRI were used together. These results suggested that the slow-release oxidants could be installed in multiple storm sewer inlets to rapidly reduce any oxidizable pollutants in storm runoff.

Current research on advanced oxidation processes often focuses on removing individual organic contaminants, sometimes overlooking the impact of microplastics (MPs) on mass transfer. Real-time and precise monitoring through experimental measurements is challenging. In this study, we used computational fluid dynamics simulations to examine the effect of MPs on mass transfer in a flow-through electro-peroxone process. Our findings revealed that MPs decreased the concentration of hydroxyl radicals at the electrochemical cathode/solution interface. However, there was no significant impact on the concentrations and diffusion pathways of O₃ in the inlet gas phase and hydrogen peroxide on the electrochemical cathode surface. Additionally, the average size of MPs increased from 135.0 to 750.0 μm, and their count rose from 7474 to 10,924 particles/L. This was accompanied by increases in average turbulent kinetic energy and turbulent dissipation rate by 0.027 and 0.018 km²/s², and 0.041 and 0.702 m²/s³, respectively. These changes suggested that the enlargement and increased count of MPs hindered liquid flow, reducing the efficiency of converting gaseous O₃ to aqueous O₃. Consequently, this diminished the removal efficiency of pollutants in the electro-peroxone process. These insights are crucial for developing more efficient advanced oxidation processes for the simultaneous removal of MPs and pollutants.

Quantitative microbial risk assessments (QMRAs) infrequently include pathogen and fecal marker decay. However, this necessitates the assumption that pathogens and indicators decay at similar rates or that decay prior to human exposure is negligible, which may misestimate the infection risks. Here, we created a QMRA model incorporating pathogen (Cryptosporidium, Giardia, Enterovirus, Rotavirus, Salmonella spp., Campylobacter jejuni, and E. coli O157:H7) and fecal indicator (HF183) decay to assess the impact of decay on the probability of gastrointestinal illness estimates in a recreational water QMRA model. Neglecting to account for pathogen decay rapidly resulted in an overestimation of risk; for example, not incorporating decay resulted in a statistically significant overestimation of risk after 30 min for Campylobacter jejuni and after 13 h for all pathogens. Substituting the fecal indicator HF183 decay rates for pathogen decay rates also rapidly resulted in a statistically significant over- or underestimation of risk. HF183 best represented the decay rate of Salmonella spp. but still resulted in an underestimation of risk after 13 h. Overall, including decay rates resulted in statistically different risk estimations on realistic time scales following pollution events, suggesting that QMRAs that neglect decay overestimate the probability of illness, and the indicator ratio approach could yield overestimations or underestimations depending on the difference between indicator and pathogen decay rate constants.

Volcanic eruptions transport substantial amounts of sediment into river systems. It damages irrigation structures that depend on the nearby river for water delivery, reducing the conveyance efficiency. This study aims to propose an efficient approach for the management of sand traps as the main sediment barriers in irrigation networks within the Progo-Opak-Serang (POS) Volcanic Basin. It is accomplished by a measurable approach: a mathematical framework executed with the Hydrologic Engineering Center’s River Analysis System (HEC-RAS). This study focuses on selected sand traps: Badran, Blawong, and Pengasih. The results show that the calibrated and validated Manning’s coefficients of Badran, Blawong, and Pengasih Sand Traps are 0.014, 0.020, and 0.025, respectively. The combination of Thomas as a sorting method, Rubey as a fall velocity method, and Laursen as a transport function can represent the transport parameters of the sand traps within the POS Basin. The recommended flushing discharge and duration for Badran, Blawong, and Pengasih Sand Traps are 4, 4.4, and 1.9 m³/s and 150, 50, and 45 min, respectively, while the flushing frequency is 4, 3, and 3 times a year. The existing sand trap performance in Badran is less effective, while that of Blawong and Pengasih is less efficient. This study assists in improving food production and security by promoting sustainable irrigation systems.

The use of diatoms as ecological indicators of water quality is well established globally, with numerous studies supporting the effectiveness of diatom-based biotic indices for monitoring the ecological status of freshwaters. These metrics typically rely on the relative abundance of “indicator taxa,” their overall sensitivity to impairment, and their environmental optimum along a pollution gradient. In South America, microalgal assemblages have only recently been used to monitor and evaluate the water quality in continental waters. This study aims to design and validate a new diatom metric, the Ecuador Diatom Index (EDI), to enhance water quality assessment in Ecuadorian river basins. The EDI reflects the overall limnological condition of a river, measured through various abiotic parameters integrated into the water quality index. Biological sampling was conducted at 111 stations across the Ecuadorian river basins. Notable differences were observed in floristics and autoecological parameters compared to other diatom-based methods. Statistical analyses revealed that beyond optimum and tolerance, incorporating specific frequency of occurrence and goodness-of-fit to a Gaussian response curve improves the reliability of this metric, surpassing the results of the commonly used specific pollution sensitivity index.

1,4-Dioxane is an emerging water contaminant that is likely to be carcinogenic to humans. Its treatment is challenging due to its high water solubility, low Henry’s law constant, and low partition coefficients. Adsorption has been widely studied for removing 1,4-dioxane. Although the adsorption kinetics and isotherms of several water pollutants have been widely studied, little is known about the adsorption kinetics of 1,4-dioxane. In this study, the kinetics of 1,4-dioxane adsorption by AmberSorb and Granular Activated Carbon (GAC) were investigated. A homogeneous surface diffusion model was developed to describe the adsorption of 1,4-dioxane in continuous-flow and batch systems. The external mass-transfer and internal diffusion coefficients of 1,4-dioxane for AmberSorb (1.79 × 10^–3 cm/min and 3.52 × 10^–4 cm²/min) were determined about five- and thirty-fold larger than that of their corresponding parameters for GAC. For both adsorbents, the adsorption was limited by the mass-transfer across the fluid film that covers the adsorbent and the adsorbent–adsorbate interaction at the adsorbent surface but not limited by the diffusion within the adsorbent. While the mass-transfer across the external fluid film affected the maximum 1,4-dioxane removal percentage and the adsorption rate, the isotherm parameters mainly controlled the adsorption capacity and adsorbent service life.

Regular monitoring of drinking water quality is crucial for achieving Sustainable Development Goal 6, but conventional methods are costly and challenging to implement in low-resource settings. Community-based monitoring, facilitated by sensor technology and information and communication tools, offers a more efficient and affordable approach, yet data reliability is uncertain. This study investigated whether minimally trained nonexpert rural women could reliably monitor drinking water quality, household water treatment and safe storage practices in low-resource settings using an integrated water quality testing kit. The kit combined a mobile app with sensors for detecting chemical (hardness, pH, alkalinity, chlorine, total dissolved solids, conductivity, dissolved oxygen, oxidation–reduction potential, turbidity) and biological (Escherichia coli) contamination. The AquaGenX P/A kit was used to measured E. coli. We examined the interrater reliability and agreement between data collected by 27 rural women and our research team in 1673 rural households in Tanzania and two Indian states. Results showed robust, moderate to high levels of agreement and interrater reliability between the nonexperts and experts, suggesting the method delivers valuable water quality data. Rural women’s involvement also led to empowerment, accountability, and ownership through technology. Our results indicate community-based initiatives’ potential to improve water quality management in resource-constrained contexts.

The paper reveals the synergetic effect of bicarbonate alkalinity in enhancing the disinfection of silver-based nanocomposite film. This study originates from an in-depth investigation into how critical ions and natural organic matter in freshwater influence disinfection. The results show that the higher concentrations of chlorides (>400 mg/L) and natural organic matter (>1.5 mg/L) adversely affected the composite disinfection ability as expected. Intriguingly, the nanocomposite shows enhanced disinfection in the presence of bicarbonate alkalinity and hardness. A detailed investigation shows that bicarbonate plays a vital role in enhancing disinfection. The studies reveal a synergy between bicarbonate and Ag⁺ released from a nanocomposite film. The bicarbonates disturb the transmembrane potential gradient (ΔpH), weaken the proton motive force of (Escherichia coli), and enable an increased penetration of Ag⁺ into the cell, resulting in enhanced production of reactive oxygen species and cell damage. This synergetic effect could help reduce the costs and concentration of Ag⁺ required for disinfection and their associated risks. The cytotoxic studies against human cell lines (HaCaT) confirm that AgNC-treated water is safe for consumption. The synergetic disinfection effect of silver with bicarbonate in water helps in developing more resource-efficient and reliable silver-based disinfection systems.

Groundwater denitrification studies require the careful quantification of excess N₂ to determine that nitrate reduction has taken place. The measurement of corresponding noble gases Ne and Ar quantifies excess air N₂ and in situ degassing. We compare, for the first time, measurement results from a high-precision quadrupole mass spectrometer (QMS) with a low-cost PlasmaDetek (plasma emission detector) GC add-on capable of analyzing all three gases (N₂, Ne, Ar) from a single sample to obtain reliable data for denitrification calculations. Both methods can be used to accurately measure N₂, Ne, and Ar concentrations that are reproducible and overlap within 2σ analytical uncertainty. Moreover, we discuss different groundwater headspace gas collection methods and show that Giggenbach bottles, while limited when storing samples for long-time periods (months or more), are reliable over shorter storage periods (up to 2 or 3 weeks), compared to cold-pressed copper tube collection methods, which are deemed stable over long timeframes (years). This novel plasma detector method will enable laboratories that do not have state-of-the-art noble gas facilities to undertake reliable measurement of dissolved groundwater gases (N₂, Ne, and Ar) for groundwater denitrification studies, understand the implications of natural subsurface nitrate attenuation, and improve catchment nitrate budgets.

Biofilms in water distribution systems are complex and tenacious populations of microbes surrounded by a protective matrix that may lead to significant water-borne diseases due to contamination and compromised quality of water. To tackle this issue, several small-molecule-based antimicrobials and engineered nanomaterials were developed that show much promise in combating biofilms. Herein, organic carbon dots (LC-CDs) were successfully synthesized from Lantana camara leaf extract, which is an invasive plant, using a one-pot hydrothermal method, requiring no chemical modifications. These LC-CDs were found to be less toxic and exhibited antibacterial and antibiofilm properties, indicating their potential use to combat biofilms. While natural carbon dots have been extensively studied for bioimaging, their antibiofilm activity has not been widely explored. Our study explores the antibacterial activity of naturally derived carbon dots through the generation of reactive oxygen species, thereby expanding the industrial prospects of this system as an antibacterial and antibiofilm agent. The LC-CDs may serve as antibacterial and antibiofilm agents to facilitate clean water production.

Denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) compete in reducing sediment conditions where DNF permanently removes nitrogen (N), while DNRA retains N with the conversion of nitrate (NO₃^–) to ammonium (NH₄⁺). Thus, an increase in the level of DNRA can undermine permanent N removal. We investigated the relative magnitude and controls of these two processes at two milldam-affected riparian sites. DNRA (5.2–37.6 μg L^–1 h^–1) accounted for 10–79% of total NO₃^– reduction and was highest in riparian sediments with higher iron (Fe) and sodium (Na⁺) in groundwater. DNF was the primary mechanism for NO₃^– reduction when Fe and Na⁺ concentrations were low but when NO₃^– was elevated. DNRA rates were higher for treatments with higher dissolved organic carbon (DOC):NO₃^– and Fe:NO₃^– ratios, indicating the stimulation of both heterotrophic and Fe²⁺ driven autotrophic DNRA. DNF and DNRA rates and their microbial functional genes decreased with increasing sediment depths. These findings imply that hydrologically stagnant and persistently reducing conditions associated with relict milldams and similar anthropogenic structures may enhance DNRA at the expense of DNF and undermine permanent N removal in riparian zones. Thus, the effects of such structures need to be accounted for in watershed N management strategies.

Per- and polyfluoroalkyl substances (PFAS) released from common consumer products, such as cosmetics and carpets, are nonpoint sources of environmental contamination. However, detailed information on PFAS mass and emission rates from these products is limited. Here, we propose a methodology to develop PFAS footprint from the manufacturing and supply chain data of cosmetics and carpets. Our analysis combines geospatial and statistical assessments to understand how the production and consumption of these products contribute to existing PFAS contamination hotspots in the Continental United States (CONUS). Statewide mass estimations revealed that North Carolina and New York contribute to the major PFAS mass released from cosmetics, while Georgia and California contribute to the major PFAS mass released from carpets. The average per capita PFAS footprint from carpets and cosmetics is about 103 mg/year. Upon disposal, over 60% of the mass eventually ends up in landfills. The accumulation of PFAS stocks in landfills, primarily from carpets and to some extent from cosmetics, highlights the critical need to cease the production and use of PFAS in consumer products. Coastal counties are particularly vulnerable due to higher population and therefore higher consumption of these PFAS-tainted consumer products. Additionally, counties with densely populated areas and with preexisting contamination sources would face increased vulnerability to PFAS contamination released from various consumer products.

Biodegradable dissolved organic carbon (BDOC) in rivers is crucial for regulating organic carbon degradation and greenhouse gas emissions during carbon transport from land to ocean. BDOC is closely linked to the biolability of riverine dissolved organic matter (DOM). However, the bioavailability of allochthonous DOM, the dominant source of DOM in large rivers, remains unclear. In this study, stable carbon isotope, excitation–emission matrix fluorescence, and Fourier transform ion cyclotron resonance mass spectrometry analyses were performed to investigate the effects of DOM sources on DOM bioavailability in the Yangtze River. The results indicate that BDOC is an important fraction of dissolved organic carbon (DOC) in the Yangtze River (29.82 ± 15.30%). Autochthonous source contributed 38.21 ± 25.42% to total biolabile DOM, exhibited saturated characteristics, and primarily comprising CHOP and CHOS compounds. Surprisingly, allochthonous biolabile DOM accounted for 34.41 ± 27.53%, emphasizing relatively high oxidation state and aromaticity with enriched heteroatomic contributions. Prolonged water retention in the Three Gorges Dam region promotes allochthonous biolabile DOM degradation, whereas increased human activity downstream leads to autochthonous biolabile DOM accumulation. This study highlights allochthonous contributions to DOM biolability and indicates that continued increases in terrigenous inputs can enhance riverine BDOC, thereby influencing CO₂ release from rivers.

Suspended sediment is a critical water quality parameter and an indicator of geomorphic processes, but suspended sediment dynamics in urban streams may not conform to the first-flush model widely used for other pollutants. We analyzed discharge and turbidity data for 367 events from three urban watersheds (impervious cover 16–45%) in Cleveland, Ohio (USA). Less intensely urbanized watersheds exhibit higher turbidity compared to that of the most highly urbanized watershed. Proportionally, more counterclockwise hysteresis is observed in the two less urbanized watersheds, and more clockwise hysteresis occurs in the highly urbanized watershed. However, hysteresis patterns are driven by different mechanisms in each watershed, and geomorphic analysis was critical to identifying the underlying mechanisms. In the least urbanized watershed, spatial rainfall variability controls sediment hysteresis. In the intermediate watershed, the erosion of upstream weathered shale banks during dry periods plays a significant role in the sediment supply and shaping hysteresis. In the most urbanized watershed, high eroding banks in downstream reaches lead to more frequent clockwise hysteresis. Overall, we suggest that as the impervious surfaces increase, the availability of instream sediments (bed and banks) plays an increased role in suspended sediment dynamics, and geomorphology remains essential for guiding management decisions.

As a complementary or alternative approach to experiments, theoretical computation of adsorption between carbon materials and emerging aromatic organic contaminants (AOCs) is increasingly important in elucidating adsorption mechanisms and characteristics, as well as their predictions. In this study, the adsorption energies between graphene and 112 AOCs were first analyzed by density functional theory (DFT-D). By the use of quantum molecular descriptors, different machine learning (ML) algorithms were developed. EXtreme gradient boosting exhibited the best performance among the four ML algorithms investigated, showing the lowest root-mean-square percentage error of 4.5% for the test data set. Accordingly, the interpretable ML technique (i.e., SHAP) assessed the importance and dependence of descriptors in the adsorption mechanisms of AOCs to graphene. The global interpretation confirmed that the molecular-volume-induced van der Waals interactions including π–π stacking are dominant, whereas the other interactions (e.g., induced hydrogen and electrostatic interactions) are comparably less significant in the adsorption of most AOCs on graphene. In contrast, using local interpretation, hydrogen bonds and induced dipole interactions with surrounding water were identified as important explanatory variables in the adsorption of AOCs containing carbonyl and sulfur functional groups. Therefore, the developed DFT-D-based ML models could be a reference model for theoretical and experimental studies.

This study investigated changes in groundwater dissolved organic matter (DOM) composition resulting from leachate leakage and examined the causes of these changes by simulating the contamination process through soil column and adsorption experiments. The results showed that contaminated groundwater had higher humification degree, chemical diversity, and unsaturation of DOM compared to uncontaminated groundwater. Five fractions were identified in landfill leachate, with fulvic-like acid and building blocks of humic substance fractions (0.45–2.5 kDa) being poorly retained by soil upon leakage. In contrast, high-molecular humic-like acid and biopolymer fractions (>2.5 kDa) as well as low-molecular organic fractions (<0.45 kDa) were readily adsorbed in soil, leading to the appearance and intensification of characteristic fluorophores at excitation/emission wavelengths of 250, 310, 365 nm/460 nm in contaminated groundwater. The characteristic fluorophore representative molecules comprised highly unsaturated structures with low- and high-oxygen content (79.6%) with high oxidizability, aromaticity, and unsaturation. To the best of our knowledge, this was the first report of the medium-molecular-weight organics in leachate preferentially entering groundwater rather than the low-molecular weight organics. This study facilitates to deepen the understanding of groundwater contamination by leachate leakage and provides theoretical support for early warning of leachate leakage contamination.

Sustainable waste management is the recycling, reusing, and recovery of wastes from natural sources. This research studied the conversion of Pinus sylvestris residues into sustainable biochars with improved properties for the adsorption of Co(II) and Ni(II) with further usage of spent biochars in the removal of carbamazepine. The biochars possessed high surface areas and abundant chemical composition with equilibrium adsorption capacities of 0.38 mmol/g for Co(II) and 0.48 mmol/g for Ni(II), forming cobalt phosphate and nickel hydroxide on the biochar surface. The laden biochars efficiently removed carbamazepine through adsorption and under UV light, following a first-order kinetic model with rate constants ranging from 0.0031 to 0.0042 min^–1 and achieving an efficiency of over 80%. The complex interaction mechanisms were responsible for the reduction of the carbamazepine concentration in the studied systems. This research demonstrates that waste wood raw materials can be used as synergistic multifunctional materials.

The paper aims to assess the impacts of the hydropower plans, economic activities, flow dynamics, water quality, nutrient sediment, habitat fragmentation, and aquatics biodiversity of the river that influence the livelihoods of local fishermen. The two study areas of Sayabouly Province (Laos) and Hau River (Vietnam) were selected to conduct the study. The study explored the connection Mekong’s farmers and fishers have with their water resources and how the changes of water resources from the river affect the biodiversity of fishes and livelihoods, income, and food security and shape cultural worldviews. The study also reconnected the link between the natural resources and policies that rural people need to strengthen their livelihood strategies so they can thrive, provide food for themselves and urban populations, and ensure the environmental integrity of the Mekong basin for future generations. The changes in water quantity and quality, biodiversity, and fish production of the local communities in the Lower Mekong River have direct and indirect impacts on the livelihood of the communities. The study found the impacts of water quantity and quality on the livelihood of local communities through the impact on biodiversity and aquatic production. The findings contribute to the current knowledge gap by providing scientific information to policymakers to prevent the consequences of water insecurity on the natural ecosystem and the livelihood of local fishers and farmers in the study areas.

Poultry processing wastewater (PPW) is a nutrient-rich effluent with the potential for reuse in crop irrigation. This study investigated transforming PPW into a hydroponic nutrient solution using a pilot scale “poultryponics” system operated continuously for 222 days. The system treated ∼57 L d^–1 of real PPW and consisted of bioreactors (inoculated with a consortium of microalgae and nitrifying bacteria), clarifiers, membrane filters, a UV disinfection unit, and a deep-water hydroponic system. The system was evaluated in terms of nitrogen transformation, organic removal efficiency, and pathogen levels. Although soluble organic removal efficiencies (sCOD) were high (>80%) in all bioreactors, nitrification was limited due to high organic loading (350–800 mg sCOD L^–1), relatively short retention time (24 h), and low dissolved oxygen levels (<3.5 mg O₂ L^–1). Grow beds showed significant nitrification, indicating the importance of upstream organic removal. CO₂ supplementation (0.5% v/v) in bioreactors did not promote nitrification in the bioreactors but was beneficial for nitrification in grow beds due to pH-modulating effects. Microbiological analyses showed no Salmonella detection in bioreactors and substantial reductions in total coliform (∼40%) and aerobic plate counts (∼30%) after UV treatment. These findings demonstrate the sustainable and safe reuse of nutrient-rich industrial effluents in agriculture.

Natural hazards significantly impact drinking water availability and reliability, posing challenges in accessing sufficient quality and quantity. Understanding the connection between water access and perceptions of psychological resilience (defined as how individuals bounce back after facing a major trauma) can clarify its role in well-being postdisaster. This study surveyed 208 older adults in Puerto Rico (May–July 2021), aged 64–104 years, 65% of whom were female, to explore this linkage following Hurricane Maria. Results show a strong preference for bottled water with 86% of participants using it as a drinking source. Municipal tap water is the second most preferred at 71%, while well water is the least favored, used by less than 4%. A gender-specific effect was found in the association between municipal tap water consumption and psychological resilience, where municipal tap water consumption was associated with higher psychological resilience only among women. The findings suggest that although bottled water is the preferred choice, municipal tap water use is positively associated with psychological resilience among women postdisaster. Research is needed to replicate these findings to attempt to determine their consistency in other similar contexts and identify underlying reasons and future implications for disaster response and preparedness.

Despite decades of effort, progress in safely managed sanitation─a public sector mandate─is stalling due to limited public funding and poor governance, among other reasons. As a result, public health has suffered and environmental degradation has continued. Social enterprises that use innovative business models to provide on-site sanitation services, also known as sanitation enterprises, are considered an emerging solution. However, sanitation enterprises have not yet successfully replaced public provision at scale. This work explores the barriers that sanitation enterprises encounter in lower- and middle-income countries. Q-Method, a mixed-methods approach that assesses social perspectives on an issue, is used to evaluate major barriers and groups of dominant perception for 19 sanitation enterprises operating across 20 countries. A total of 25 mutually exclusive, collectively exhaustive barriers are identified, ranging from affording capital expenses to navigating political corruption. The results show that most of the identified barriers fall into the financial barrier category, with reaching economies of scale being the greatest obstacle for sanitation enterprises. On the basis of these results, the premise of independent profitability underlying the sanitation enterprise value proposition should be reevaluated. Four enterprise types are proposed and can explain half of the variance among the sanitation enterprises studied. The context of a sanitation enterprise, including its countries of operation, size, customer base, sources of revenue, and section of the sanitation value chain, influences the barriers that the enterprise encounters. This research underscores the crucial role of context in influencing barriers for sanitation enterprises, emphasizing the need for investment and for policy makers to take these contextual dimensions into account.

Though diatoms as agents to remove silica pollutants have already been tested, the factors governing the photobiological process remain unexplored. The current process was developed to optimize various combinations of abiotic factors like pH (5, 6, 7, 8, and 9), mixing conditions (aeration, magnetic stirrer, and shaking-induced mixing), and light wavelength (red: 665–630 nm, blue: 465–430 nm, and white: 665–420 nm) for silica removal using diatom Navicula sp. from WC media. A combination of pH 7 and magnetic stirrer mixing (80–100 rpm) gave the best silica removal at 11.93 ± 0.15 mg L^–1d^–1. This optimized process with blue wavelength light increased the silica removal rate to 14.43 ± 0.37 mg L^–1d^–1 and biomass productivity to 95.15 ± 1.34 mg L^–1d^–1. Further, bioremediation of cooling tower blowdown water was tested under optimized and unoptimized conditions. A silica removal rate of 13.90 ± 0.26 mg L^–1d^–1 was achieved under optimized conditions, 3.69-fold greater than the unoptimized conditions (3.77 ± 0.42 mg L^–1d^–1). Additionally, this process removed >99% of total dissolved phosphate (3.05 ± 0.10 mg L^–1d^–1), nitrate nitrogen (12.27 ± 0.49 mg L^–1d^–1), and 54.27% chemical oxygen demand. Such optimization of abiotic factors using diatoms helps in achieving green silica-rich wastewater bioremediation.

This study tried to reveal how the implementation and cancellation of the dynamic zero-COVID policy could affect the development of the epidemic through wastewater surveillance of SARS-CoV-2 in Beijing during its first COVID-19 surge. A total of 443 24 h composite wastewater samples were taken from seven manholes and 10 wastewater treatment plants immediately on December 7, 2022, when the new COVID-19 policy was implemented, for the detection of SARS-CoV-2. The results showed that the first COVID-19 surge in Beijing was characterized by a rapid outbreak, short duration (one month), and extremely high infection rate (92.8%). Wastewater tiling amplicon sequencing showed that the main subvariant for this surge was BF.7.14 (65%), which has never caused an outbreak in other countries in the world. The variant BF.7.14 appeared in Beijing on August 15, 2022, as an imported case and then managed to retain and become a dominant variant as the strict dynamic zero policy had blocked the entry of other more infectious SARS-CoV-2 variants. This is the first study to capture the unique picture of the epidemic development in Beijing during its first COVID-19 surge, demonstrating that the strict dynamic zero-COVID strategy could shape the infection patterns greatly.

Nanoplastics possess unique characteristics (e.g., high surface area/volume ratio) that enhance the adsorption of organic chemicals onto their surface. Their occurrence raises human health and ecotoxicological concerns, as pollutants bound to nanoplastics can have a larger effect than they would on their own. This study assessed the sorption of plant protection products (glyphosate and methyl parathion), an antidepressant (fluoxetine), a perfluorochemical (perfluorooctanoic acid [PFOA]), and a polycyclic aromatic hydrocarbon (phenanthrene) onto commercially available carboxylated polystyrene (PS) nanoplastics (NPs, 500 and 20 nm). Based on the calculated sorption coefficients (K_d, L/kg), the sequence of chemicals displaying the highest to lowest affinity toward PSNPs is fluoxetine > phenanthrene > methyl parathion > PFOA > glyphosate, with 20 nm PS showing a higher potential to sorb organic chemicals. Cationic (fluoxetine) and hydrophobic (phenanthrene) substances were more amenable to sorption, whereas negatively charged and more hydrophilic ones (i.e., PFOA and glyphosate) showed poor sorption. pH influenced sorption for all target chemicals except phenanthrene. Sorption capacity was further reduced in water spiked with natural organic matter and in tertiary-treated wastewater effluent. Overall, our work enhances the understanding of how representative organic chemicals sorb onto nanoplastics and provides quantitative information (i.e., K_d) on future simulations of nanoplastics’ fate and transport.

Water-based recreational activities can impact freshwater systems, but the resulting anthropogenic alterations to the chemical and microbial composition of natural streams remain poorly understood. Utilizing state-of-the-art analytical approaches, including liquid chromatography-high-resolution mass spectrometry (LC-HRMS), inductively coupled plasma mass spectrometry (ICP-MS), and 16S rRNA gene sequencing, we investigated changes in stream chemistry and microbiology resulting from recreational activities in Clear Creek (Golden, Colorado). Spatial and temporal sampling was conducted for 3 days over a summer holiday weekend when a large influx of recreational float tubing activity occurred. Nontarget LC-HRMS analysis demonstrated substantial differences in the organic fingerprint on days and locations with high recreational use compared to that of low use. Similarly, increases in the total suspended solids were correlated with suspended particulate metal concentrations (Al, Cu, Ti, Pb, and Zn). Element ratios suggest recreation-induced resuspension of streambed sediments as the metal source rather than other anthropogenic inputs (e.g., Ti/Zn-containing sunscreens). Gene sequencing revealed significant shifts in the stream microbial community, supporting an input of human-associated enteric microbiota during high recreation periods. However, the overall results indicate that recreational activities have a short-lived effect on the stream. In this work, we established a first-of-its-kind holistic assessment of the impact of anthropogenic activity on a natural stream by simultaneously considering changes in the organic, inorganic, and microbial fingerprints.

Monochloramine (MCA) is commonly added to drinking water as a disinfectant to prevent pathogen growth. The generation of MCA at the treatment plant requires tight control over both pH and the ratio of free chlorine (FC) to ammonia to avoid forming undesirable byproducts such as dichloramine (DCA) and trichloramine (TCA), which can impart odor and toxicity to the water. Therefore, continuous monitoring of MCA is essential to ensuring drinking water quality. Currently, standard colorimetric methods to measure MCA rely on the use of reagents and are unsuitable for online monitoring. In addition, other oxidants can interfere with MCA measurement. Here, we present a solid-state, reagent-free MCA sensing method using an array of few-layer graphene (FLG) chemiresistors. The array consists of exfoliated FLG chemiresistors functionalized with specific redox-active molecules that have differential responses to MCA, FC, and DCA over a range of concentrations. Chemometric methods were employed to separate the analytes’ responses and to generate multivariate calibration for quantification. A minimum of three sensors are required in the array to maintain full functionality. The array has been demonstrated to quantify MCA in buffered and tap water as a low-cost, reagent-free approach to continuous monitoring.

Japanese encephalitis virus (JEV) and the Murray Valley encephalitis virus (MVEV) are mosquito-borne pathogens capable of transmission from animals to humans, causing significant economic and public health impacts in affected countries. Pigs serve as amplifying hosts for JEV and potentially play a role in the natural ecology of MVEV. Reports of JEV viral shedding underscore the prospect of wastewater surveillance for early detection and intervention for animal and human health. To assess the feasibility of wastewater surveillance, the decay rates of JEV and MVEV RNA were determined under the simulated diurnal temperatures in summer and winter by seeding these viruses in piggery wastewater collected from three potential surveillance sites (shed, pit, and lagoon). During a 52-day experiment, a one log₁₀ reduction in RNA copies was found for JEV within 24.8–36.4 days, while MVEV experienced a 90% reduction ranging from 15.5 to 24.4 days, which was significantly faster than that of JEV. Seasonal temperature and site-specific differences significantly influenced the RNA decay rates of both viruses in piggery wastewater samples. These data indicated the sufficient persistence of JEV and MVEV under diurnal temperatures in summer and winter conditions, which would facilitate surveillance of viruses in piggery environments.

This study investigates the optimized design of horizontal flow constructed wetlands (HFCWs) to enhance pollutant removal efficiency while minimizing surface area requirements, particularly in the Southeast Asian region. By refining the first-order removal rate coefficient (k) for organics and nutrients, the research aims to meet specific performance benchmarks across three scenarios, ensuring compliance with discharge or reuse standards. Utilizing a data set comprising 1680 entries, five machine learning models─multiple linear regression (MLR), eXtreme Gradient Boosting (XGBoost), random forest (RF), artificial neural network (ANN), and support vector regression (SVR)─were employed to predict k values. Pearson’s correlation, heat maps, and ANOVA analysis identified the most influential parameters affecting k-value predictions. The k values ranged from 0.01 to 0.52 per day using the P–k–C* method, essential for effective pollutant removal. The SVR model demonstrated the highest predictive accuracy, with R² values of 0.91 for k_BOD, 0.90 for k_TN, 0.82 for k_TKN, and 0.76 for k_TP. This optimization reduced standard deviations significantly, from 136.90% to 2.28%. Consequently, the required wetland area was reduced by up to 68% for biochemical oxygen demand (BOD), 60% for TN (total nitrogen), and 67% for TP (total phosphorus) in larger systems, supporting the tailored design of HFCWs to meet targeted discharge standards.

Photocatalysis studies were performed using graphene oxide–TiO₂ (GOT) nanocomposite irradiated using 125 W UV and visible irradiation to investigate the effect of various water matrices, i.e., distilled water (DW), secondary treated wastewater (WWE), and lake water (LW) on the removal of organophosphorus pesticides from binary mixtures formulated using a 2² full factorial design. The EC₆₀ and EC₄₀ values of individual pesticides, determined from the dose response profile using the Ellman assay were used as the high and low concentrations, respectively. Photocatalysis was conducted at a GOT dose of 60 mg/L. For both Mixture-I, comprised of dichlorvos and malathion, and Mixture-II, comprised of parathion and phorate, degradation followed the order, DW > WWE > LW. After 80 min, the highest degradation of ∼80% was observed for Mixture I in DW under UV irradiation when the concentration of both pesticides was at EC₄₀. Malathion displayed a higher rate and extent of degradation and mineralization compared to dichlorvos in all of the mixture combinations. Under similar reaction conditions, phorate and parathion demonstrated similar values of the first-order degradation rate constant. Dissolved organic matter (DOM) had a detrimental effect on pesticide degradation by blocking the active sites on the catalyst and by scavenging the oxidative radicals generated during irradiation. A decrease in SUVA₂₅₄ in both WWE and LW during photocatalysis indicated the decomposition of aromatic moieties in DOM. After UV/visible photocatalysis, the lowest residual toxic effect, as measured in the Ellman assay, was observed in mixtures containing low initial concentration of both the pesticides.

In this study, we conducted quantitative polymerase chain reaction (qPCR)-based wastewater surveillance for 12 prominent respiratory pathogens in two northeastern cities of China, Dalian, and Benxi, to understand the cocirculation patterns between COVID-19 and other respiratory diseases from October 2022 to July 2023. Wastewater surveillance revealed that Influenza A virus (IAV) and respiratory syncytial virus (RSV) sewage concentrations exhibited an upward trend from October 2022 in both cities but with distinct epidemic trajectories. In Dalian, IAV and RSV sewage concentrations both peaked in early December, followed by a rapid decline since the emergence of COVID-19 on November 23, 2022. In Benxi, two bell-shaped curves were observed for IAV and RSV sewage concentrations, both peaking in mid-December of 2022, even though severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in wastewater on December 8, 2022. After a rapid decline in SARS-CoV-2 sewage concentrations in January 2023, a new wave of IAV in wastewater occurred between February and early April in both cities, followed by a surge of SARS-CoV-2 RNA in early May. Meanwhile, an out-of-season epidemic of RSV from March to May was observed in Benxi based on the cities’ sewage concentrations. This study highlights the impact of the timing of COVID-19 on the epidemic trajectories of other respiratory diseases.

Vibrio pathogens in marine estuaries pose significant human health risks through recreational water use and seafood contamination. This study used the Ala Wai Canal in Honolulu, Hawaii, as a model tropical urban marine estuary to understand the Vibrio population’s composition and associated environmental health risks. Vibrio-specific 16S rRNA gene amplicon sequencing identified diverse Vibrio populations. Among the 62 major amplicon sequencing variants (ASVs) detected, V. parahaemolyticus-clustered ASVs were significantly more prevalent than those clustered with V. cholerae and V. vulnificus. Spatial distribution of the Vibrio ASVs showed that V. parahaemolyticus-clustered ASVs were highly abundant toward the stagnant end of the canal with higher turbidity and BOD₅ than sites near the freshwater inlets and the ocean outlet. DNA fingerprinting of V. parahaemolyticus isolates obtained from the water showed significant genetic diversity, corresponding to the ASV-based diversity and indicating the presence of diverse environmental niches. The V. parahaemolyticus population in the canal water exhibited a low detection frequency of the virulence factor tdh and an antibiotic resistance profile typical of environmental isolates. The identification of V. parahaemolyticus as the most prevalent Vibrio pathogen and its enrichment within the stagnant terminus of the canal suggest that increased water circulation may change Vibrio ecology and alleviate potential health risks.

The presence of multidrug-resistant bacteria in Malaysian waters and farmed aquatic species in its estuarine environment suggests contamination due to pharmaceuticals and personal care products (PPCPs). However, this issue has lacked serious attention. This study performed suspect screening to identify tentative PPCPs in water and mussels located at the Melayu River during high and low tides, followed by a public awareness survey to understand the public behavior toward handling PPCPs. In total, 75 PPCPs were tentatively identified. Four and six compounds were found in surface water during low and high tides, respectively, while mussel samples showed 50 compounds during low tide and 35 compounds during high tide. Interestingly, 7 pharmaceuticals and 4 personal care products appeared in both tides in mussel samples. Survey findings revealed that while respondents understood PPCP pathways entering the environment and associated threats, they were unaware of relevant laws and proper disposal methods for unused pharmaceuticals, which are often discarded together with domestic wastes. The findings highlight the urgent need for detailed suspect screening with targeted analysis in order to establish relevant regulatory measures apart from providing public education on the proper disposal of PPCPs to mitigate contamination.

Enhanced biological phosphorus (P) removal (EBPR) with return activated sludge (RAS) fermentation (S2EBPR) is a recent EBPR innovation suggested to achieve more stable and efficient P removal. However, consensus around these benefits and the mechanisms of S2EBPR is still developing. To further this understanding, three pilot sequencing batch reactors treating real domestic wastewater were operated as S2EBPR or conventional EBPR, with or without external carbon addition, and as S2EBPR with or without the anaerobic phase. Findings include the following: (1) S2EBPR showed a small P removal improvement over conventional EBPR; (2) S2EBPR performed substantially better with a small dose of external carbon added, while conventional EBPR did not, but microbial community stability was increased in both; (3) when external carbon to S2EBPR was stopped, high P removal continued for two solids retention times; (4) the measured fermentation yield suggested a larger benefit to S2EBPR P removal than was observed; (5) S2EBPR without the anaerobic phase did not achieve good P removal; and (6) although microbial community trends were similar, S2EBPR enriched more metabolically flexible polyphosphate accumulating organisms than conventional EBPR, importantly, Candidatus Phosphoribacter. Overall, RAS fermentation was beneficial to EBPR performance and stability with external carbon addition but minimally without.

Streams are the primary conduits through which microplastics are transported from land to sea. Attributes of the plastic particles and of the streams are both likely to influence how microplastic moves, but there are few empirical studies of microplastic transport dynamics in real systems. We adopted the spiralling technique commonly used to measure nutrient cycling in streams to quantify transport distances and deposition velocities of microplastics in streams with varying geomorphological structure and level of human modification. We conducted pulse releases of trace amounts of three size classes of five different polymers spanning a density gradient in 15 streams. The streams were typical of the range of human modification in urban environments, from seminatural to highly modified. Transport distances of microplastic ranged from <1 to 111 m, with distances declining with particle size. Neutrally buoyant polymers had the longest transport distances and lowest deposition velocities. Streams that had been modified into concrete channels were the most effective in transporting microplastics downstream, as indicated by relatively low deposition velocities and long transport distances of microplastics. Our results suggest that the movement of microplastic pollution in streams depends on the physical characteristics of the stream more than on plastic properties.

The contamination of natural water bodies with dyes and other refractory compounds is a menacing issue in developing nations. Despite stringent laws, industrial effluent is not managed efficiently, as it incurs additional cost. Hence, the present research focuses on sustainable mitigation of refractory contaminants using a self-driven bioelectro-Fenton (BEF) system. The iron-activated charcoal (Gt-Fe/AC) cathode-cum-Fenton catalyst used in this investigation was synthesized using waste green tea extract as a biogenic agent. The green catalyst-driven BEF system (Gt-Fe/AC-MFC) achieved a maximum power density of 111.7 ± 3.1 mW/m² and a maximum operating voltage of 108 ± 3 mV, while parallelly degrading 20 mg/L of Coomassie Brilliant Blue (CBB) dye almost entirely in 300 min at a neutral pH. Additionally, high removal of Congo red dye (96.8 ± 1.2%) and methylparaben (90.9 ± 0.6%) was attained under similar operating conditions. Moreover, the Fe-AC-catalyzed BEF performed fairly well in treating spiked real wastewater and exhibited remarkable stability, with only a 3% decrease in CBB removal efficiency after 10 continuous cycles and 0.11% drop in cathodic current per cycle. Hence, this BEF system can be a sustainable oxidative technology to tackle refractory wastewater in resource-constricted regions.

In this study, bacteria Bacillus cereus and Bacillus xiamenensis were used for the biosorption of Cd (II) and Cr (VI) from wastewater. The effects of contact time, pH, and metal ion concentration on the biosorption of Cd (II) and Cr (VI) were studied. The minimum inhibitory concentration (MIC) exhibited by Bacillus cereus was 6 mM for Cd (II) and 7 mM for Cr (VI), and that of Bacillus xiamenensis was 8 mM for Cd (II) and 7 mM for Cr (VI). Bacillus xiamenensis achieved a maximum uptake of 90.70% for Cr (VI) and 84.32% for Cd (II), while Bacillus cereus achieved a maximum uptake of 96.87% for Cr (VI) and 92.15% for Cd (II) in 60 min. The maximum adsorption capacities of Bacillus xiamenensis for Cd (II) and Cr (VI) were 150.02 and 201.2 mg/g, respectively, while the values for Bacillus cereus were 180.76 and 273.49 mg/g for Cd (II) and Cr (VI), respectively. The isotherm study showed that the biosorption data of Cd (II) and Cr (VI) fitted well with the Freundlich isotherm model. The results revealed that Bacillus cereus and Bacillus xiamenensis exhibited promising potential for the removal of Cd (II) and Cr (VI) from metal-contaminated water.

Here, we present the first systematic and comprehensive analysis of the biochemical and transcriptomic characteristics of Microlunatus phosphovorus NM-1 with glucose and amino acids as carbon sources for enhanced biological phosphorus removal (EBPR). Glucose-induced the highest P release rate, followed by aspartate and glutamate. Its anaerobic P release and glucose uptake and aerobic P uptake kinetics exceeded those of Tetrasphaera and Candidatus Accumulibacter (with acetate). Anaerobic glucose uptake and activation were achieved via the phosphoenolpyruvate-dependent phosphotransferase system and bifunctional glucokinases, contributing to its exceptionally high glucose uptake rates. Aspartate and glutamate uptake was driven by proton motive force. Glucose and those amino acids were mainly stored as glycogen. Novel pathways (beta-oxidation and fatty acid biosynthesis) were encoded by NM-1 for polyhydroxyalkanoate generation. Transcriptomic analysis revealed significantly transcribed genes in the glyoxylate cycle in anaerobic glucose metabolism. Glutamate and aspartate were deaminized and routed into the TCA cycle for glycogen and polyhydroxyvalerate generation. Two low-affinity phosphate transporter genes were distinctly transcribed in the anaerobic and aerobic phases, benefiting enhanced P release and uptake. Collectively, this study provides a comprehensive understanding of the glucose and amino acid metabolism of NM-1, benefiting an improved description and modeling of the M. phosphovorus-mediated EBPR process.

While numerous assessments of micropollutant exposure primarily focus on monitoring the water column, a growing body of research indicates that differences in micropollutant partitioning in other compartments require additional consideration for risk evaluation. This study investigated the partitioning of antibiotics, antiepileptics, antibacterials, and antidepressants and their metabolites in water, sediment, macroinvertebrates (gammarids), biofilm, and fish (spoonhead sculpin and longnose dace) found or exposed in replicate naturalized streams (Calgary, Alberta, Canada). All target micropollutants were detected in the water and sediment, and >5 substances were detected in the biotic matrices at concentrations between the limit of quantitation and 244 ± 16 ng/g_dw. Triclosan and triclocarban (antibacterials) were frequently detected in sediments, but very rarely in the water column. The solid–water partitioning (K_d) and organic carbon–water partitioning coefficients (K_oc) indicate that fluoxetine, norfluoxetine, and triclosan have a stronger affinity for sediments and/or organic matter (log K_d > 2.7, log K_oc > 1.5). More specifically, fluoxetine was found to be up to 10× higher in sediments, biofilm, and gammarids than other substances, whereas its concentration in the water column was very low or nondetectable. Finally, bottom-dwelling fish (spoonhead sculpin) were also found to have higher concentrations of fluoxetine and its metabolite than longnose dace.

Residents and their pets may experience aesthetic or health concerns resulting from elevated copper in their drinking water. The United States Environmental Protection Agency Lead and Copper Rule focuses on addressing systemwide corrosion issues, but gaps in the rule leave some municipal water consumers and residents with private well water vulnerable to high cuprosolvency. We developed guidance to aid residents in understanding, detecting, and addressing cuprosolvency issues in their drinking water. Three types of at-home test kits for copper and one for pH were determined to be accurate enough (R² > 0.9 (lab, based on average values from n = 5 replicates each) and >0.7 (field)) to detect concerns related to high cuprosolvency and inform selection of intervention options. Case study results indicate that, although water treatments such as increasing pH on-site may be effective, long-term treatment (>36 weeks or permanently) may be needed to maintain reductions in cuprosolvency. A decision tree is provided to help residents and citizen scientists navigate these concerns for both public water systems and private wells.

Adsorption of aqueous organic pollutants onto microplastics influences the exposure and risks of both the pollutants and microplastics. Experimental determination of the aqueous adsorption equilibrium constants (K_aq) that characterize the adsorption capacity of microplastics to pollutants is laborious and inefficient since the K_aq values rely on various combinations of conditions, such as pH, ionic strength, and particle sizes. Herein, molecular dynamics (MD) methods were established by comparing the MD-calculated K_aq values with the empirical values of 14 compounds adsorbed onto polyethylene (PE) microplastics having different particle sizes (10–250 μm) in pure water and seawater. Based on the data sets consisting of experimental and MD-calculated K_aq values, machine learning models were constructed. A gradient boosting decision tree (GBDT) model requires only easily obtainable Mordred descriptors for pollutants and desired conditions (particle sizes and ionic strength) to yield accurate results, with an external determination coefficient of 0.99. The GBDT model exhibits a great improvement over the previous one, as it incorporates multiple factors including ionic strength from pure water to seawater, dissociation species at different pH, and PE particle sizes with diameters ranging from nanometers to micrometers. This study paves a new way for high-throughput estimating K values for microplastics and pollutants at different environmental conditions.

Rivers play a non-negligible role in global methane (CH₄) emissions. However, little research has focused on CH₄ emissions from rivers with high suspended sediment (SPS) concentrations, and how SPS influences riverine CH₄ emissions is still unclear. In this study, significant CH₄ emissions were observed in the upper reaches of the Yellow River, despite the extremely low organic-C level (DOC = 2.2 mg/L). The average value of CH₄ flux was 107.7 μmol m^–2 d^–1, which was even higher than that of urban rivers with high organic pollution. The CH₄ emission pattern in the Yellow River differed from that of typical rivers; SPS rather than sediment plays an important role. In the upper reaches, anaerobic/aerobic microenvironments are more easily established on SPS under lower DO conditions, resulting in a high abundance of methanogens and functional genes. The genus Methanobacterium, typically found in sediments, was dominant in the water column and positively related to SPS concentrations. The strong winds and water flow further enhanced the mass transfer from the SPS surface to the atmosphere. Overall, this study demonstrates the significant potential of low-organic-country rivers to act as CH₄ hotspots in the presence of SPS.

Fluoroquinolones, a class of antibiotics, have been detected in various aquatic environments, including those experiencing freeze–thaw cycles. This study investigated the adsorption of ciprofloxacin (CIP) in frozen (−21 °C) and aqueous (25 °C) solutions under varying pH levels, electrolyte types, and ionic strengths. CIP sorption on goethite was found to be transient, as freezing re-establishes equilibrium, nearly doubling CIP loadings at acidic to circumneutral pH values. The original equilibrium was restored by thawing. Our investigation reveals that ion pairs, formed between the positively charged piperazine group of CIP and anions (Cl^–, Br^–, and NO₃^–), create a charge-shielding effect, explaining the transient nature of CIP sorption equilibrium at goethite-water interfaces. In situ ATR-FTIR observations and model predictions further confirm the significant role of ion-paired surface complexes in transient CIP sorption. The transience of CIP sorption equilibrium in frozen and aqueous solutions is attributed to the local concentrations of anions, which undergo freeze-concentration into liquid intergrain boundaries and dilution by reversible ice nucleation and thawing. As the interaction between the hydrosphere and cryosphere intensifies with climate change, these findings have significant implications for evaluating the fate of contaminants in both terrestrial and aquatic environments.

Nitrogen-removing biofilters (NRBs) are alternative on-site wastewater treatment systems that can remove some trace organic contaminants (TOrCs) from domestic wastewater, though the dominant removal mechanisms are uncertain. We conducted column experiments representative of the nitrifying sand layer of an NRB to evaluate the contribution of sorption to removal of 16 wastewater-relevant TOrCs. The contribution of sorption was >25% for eight of the 16 TOrCs in at least one experimental treatment and >50% for five TOrCs. Transformation appeared to account for 51–93% of TOrC removal in columns. Transformation product screening resulted in the tentative identification of three TOrC transformation products in column effluent. To compare the bench-scale experiment to realistic field conditions, we analyzed solid samples from a recently excavated full-scale NRB. Median concentrations of sorbed TOrCs ranged from 0.02 to 5.09 ng/g in column studies and 0.05–7.14 ng/g in the full-scale NRB. Overall, the majority of TOrC removal in our laboratory study was by transformation, though some hydrophobic TOrCs exhibited significant removal by sorption. The concentration of sorbed hydrophobic TOrCs in aged NRBs and release of transformation products of frequently detected TOrCs should be taken into consideration during future system design and optimization.

The architectural configuration of an electrode material significantly impacts its capacitive deionization (CDI) performance, particularly due to the disparity in ion diffusion resistance between the surface and core. To mitigate this disparity, a hollowing methodology was employed to revamp conventional porous carbon spheres. Hierarchically porous hollow carbon spheres (HCSs) were synthesized by thermal annealing phenol formaldehyde resin-coated melamine formaldehyde resin spheres (MFSs) in an inert gas at 800 °C. The advantage of employing modified MFSs as templates lies in their complete degradation during thermal annealing, a feature not observed with commercial polystyrene microspheres. Unlike mesoporous SiO₂ microspheres which require additional hydrofluoric acid treatment, these do not. HCS-100 exhibited exceptional NaCl adsorption capacity, achieving a salt adsorption capacity of 25.20 mg g^–1 and a salt adsorption rate of 2.78 mg g^–1 min^–1 under a working voltage of 1.2 V. This performance was demonstrated with an initial NaCl solution concentration of 500 mg L^–1, and it maintained impressive stability over 70 cycles. The results demonstrate that the hollowing strategy is a direct yet powerful way to enhance the CDI performance of electrode materials. The utilization of the modified MFS template simplifies the fabrication process, contributing to the overall effectiveness of this approach.

The compounds generated during wastewater treatment processes might increase the complexity and chemical risk assessment of wastewater-derived dissolved organic matter (DOM) released into receiving water. This study applied Fourier transform ion cyclotron resonance mass spectrometry to investigate the dynamic changes in wastewater composition at the molecular level in a full-scale municipal wastewater treatment plant (WWTP). Approximately 63.1% of the detected molecules in the effluent were derived from the influent. N/S-containing molecules were more effectively removed than CHO molecules in the studied WWTP. The dealkylation and oxygen addition reactions of N-containing molecules, along with the predominant N-addition reactions of removed molecules observed in anaerobic and oxic tanks, contributed to the higher N/C_wa in the effluent than in the influent. However, the S-containing molecules could be effectively removed via S-loss reactions in the anoxic/anaerobic/oxic (inverted A/A/O) processes. Dealkylation and oxygen addition reactions were found to be the predominant reaction types in all tanks of the inverted A/A/O processes. More oxidized molecules with higher aromaticity and unsaturation degree were observed in the effluent than in the influent. Our findings provide a comprehensive view of the transformation of wastewater DOM in a full-scale WWTP and offer valuable insights into effluent water quality.

Solar interface evaporation is considered an innovative and effective technology for combating global freshwater scarcity, with its effectiveness primarily hinging on the efficiency of photothermal materials. Here, we designed a solar evaporation device comprising a sponge layer for water collection and a polypyrrole (PPy) layer chemically deposited on a single-sided flannel (PPy@SSF) for sunlight absorption. The fiber array within PPy@SSF facilitates to absorb light energy, establishing a heating interface between the light absorption layer and the water. The sponge layer not only aids in water collection but also serves as a thermal insulation layer, preventing heat dispersion. The resulting device exhibits characteristics such as high water evaporation, robust stability, and resistance to salt. The daily water output reaches 8.12 kg m^–2 under direct sunlight. In desalinating simulated seawater, the ion concentrations in the condensed water were reduced by 4 orders. Furthermore, heavy metal ions in purified water from sewage were reduced by at least 3 orders of magnitude. Additionally, the properties of the device showed no attenuation after being used repeatedly 10 times under 1 sun. Our research provides a platform with high photothermal conversion efficiency for seawater and sewage purification.