Water Environment Research[JOURNAL]
Sun
200 papers
Hydrogeochemical Signatures, Genetic Processes, and Resource Implications of Groundwater in an Arid High-Altitude Urban Basin on Tibetan Plateau.
Yang D, Hu W, Wang W … +9 more , Xiao Y, Wang S, Zhang S, Zhang Y, Ma Z, Chen H, Guo X, Wang J, Zhang G
Water Environ Res · 2026 Feb · PMID 41717837 · Publisher ↗
Groundwater serves as an indispensable freshwater source in arid high-altitude urban basins. This study investigates the western Xining city on northern Tibetan Plateau, to elucidate the hydrochemical characteristics, ge...
Groundwater serves as an indispensable freshwater source in arid high-altitude urban basins. This study investigates the western Xining city on northern Tibetan Plateau, to elucidate the hydrochemical characteristics, genetic mechanisms, and resource implications of its groundwater in arid urban basins. A comprehensive approach integrating hydrochemical and statistical analyses, the entropy-weighted water quality index, and irrigation suitability evaluation was employed. The results show groundwater in the present arid high-altitude urban basin is generally neutral to weakly alkaline, exhibiting marked spatial variability in total dissolved solids (TDS), with 47.83% exceeding drinking water standards. Along the groundwater flow path, the hydrochemical facies evolve from HCO-Ca type to mixed Cl-Mg·Ca type and ultimately to Cl-Ca type, reflecting a clear salinization trend. Groundwater chemistry is mainly governed by silicate weathering, with secondary contributions from carbonate and evaporite dissolution, accompanied by limited cation exchange. Anthropogenic influences, particularly agricultural fertilization, have caused extensive nitrate enrichment, affecting 96% of the samples. River water exhibits excellent quality and is suitable for direct consumption, whereas only 56.5% of the groundwater meets drinking water standards, with the remainder classified as medium to poor quality. Regarding irrigation suitability, river water is highly favorable, and most groundwater is also acceptable. However, certain localities show elevated salinity and sodium hazards, highlighting the need for enhanced management to ensure sustainable water resource utilization. This study elucidates the hydrochemical genesis of groundwater in fragile plateau urban environments and contribute to sustainable local water resource management.
Investigation of Blackening Substances of "Black Water" Occurrence in the Reservoirs With Eucalyptus Plantations, Southern China.
Pan Y, Wu P, Liang L … +6 more , Zhao S, Guo J, Lyu W, Li C, Wang S, Jia R
Water Environ Res · 2026 Feb · PMID 41717831 · Publisher ↗
The frequent occurrence of "black water" in water source reservoirs with Eucalyptus plantations in Guangxi, China, during winter poses a risk to local drinking water safety. Knowledge of the key blackening substances and...
The frequent occurrence of "black water" in water source reservoirs with Eucalyptus plantations in Guangxi, China, during winter poses a risk to local drinking water safety. Knowledge of the key blackening substances and their molecular compositional characteristics responsible for reservoir water blackening is essential for black water remediation in drinking water reservoirs of Eucalyptus forest areas. This study utilized advanced techniques, including Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), to analyze the molecular composition of soluble organic compounds in both Eucalyptus leaf soaking solutions and water from Jinwo Reservoir and Tianbao Reservoir, which are representative of Eucalyptus forest areas. The findings indicate that the Eucalyptus leaf soaking solution is predominantly composed of aromatic polyphenols, including pyrogallol and gallic acid as parent compounds, along with their polymerized derivatives, among which ellagic acid (CHO) is the most typical compound. Ellagic acid concentrations are higher in winter reservoir water compared to summer, particularly in surface water versus bottom water. This suggests that the aromatic polyphenols released from fallen Eucalyptus leaves during autumn and winter are the primary substances responsible for the blackening of reservoirs, with ellagic acid being the key blackening substance. Gallic acid reacts with iron ions under neutral conditions to form a black solution without precipitation. The resulting complex intermediate was identified as [CHOFe] using FT-ICR MS. This finding further confirms, at the molecular level, that aromatic polyphenols (e.g., ellagic acid and gallic acid) leached from Eucalyptus leaves can bind with iron ions to form black metal-organic complexes, thereby contributing to the blackening of reservoir water. The findings offer crucial insights for effective management and ensuring the safety of drinking water in such reservoirs.
Incorporation of Paddy Husk Biochar and the Effectiveness of Colocasia esculenta Usage in Vertical Flow Constructed Wetlands for Treatment of Synthetic Wastewater Having "Rhodamine B".
Sirimanna RGHL, Nadarajah K
Water Environ Res · 2026 Feb · PMID 41711082 · Publisher ↗
Incorporation of paddy husk biochar (PHBC 350) and Colocasia esculenta (C. esculenta) usage in vertical flow constructed wetlands (VFCWs) for treatment of synthetic wastewater mixed with rhodamine B (RhB) was the focus....
Incorporation of paddy husk biochar (PHBC 350) and Colocasia esculenta (C. esculenta) usage in vertical flow constructed wetlands (VFCWs) for treatment of synthetic wastewater mixed with rhodamine B (RhB) was the focus. To increase the removal efficiency of VFCW, pebbles (0.0125 m), sand (0.005 m), and PHBC 350 (0.0075 m) were used. Setups of VFCWs, S (sand) and SB (sand + biochar [30% v/v]), were established. DO, pH, TS, TDS, TSS, EC, color, turbidity, dye concentration, and RhB removal percentage were evaluated. The measured values of DO, EC, pH, TS, TDS, and TSS in SB were 6.03 mg/L, 1.72 mS/cm, 6.14, 1080 ppm, 860 ppm, and 220 ppm, respectively, in 10 days. Moreover, SB gave a statistical level of RhB removal of 81.5%. All in all, incorporation of biochar into VFCWs created new knowledge to advance the removal performance for wastewater mixed with organic pollutants by understanding its mechanistic dynamics.
Comparative Evaluation of Machine Learning Models for Spatio-Temporal Groundwater Quality Prediction and Classification in the Muvattupuzha River Basin, India.
Alagulakshmi K, Gautam S, Arulraj GP … +1 more , Ho CH
Water Environ Res · 2026 Feb · PMID 41703671 · Publisher ↗
Groundwater contamination has increased significantly due to population growth, land-use change, and unsustainable resource exploitation, necessitating advanced predictive tools for effective water governance. This study...
Groundwater contamination has increased significantly due to population growth, land-use change, and unsustainable resource exploitation, necessitating advanced predictive tools for effective water governance. This study presents a multi-temporal, comparative machine learning (ML) to evaluate groundwater quality in the Muvattupuzha River Basin, Kerala, India, using datasets from 2003, 2013, and 2023. A total of five supervised ML models (i.e., decision tree [DT], logistic regression, support vector machine, random forest, and k-nearest neighbor) are systematically assessed to distinguish groundwater as safe or unsafe. Model performance is evaluated using accuracy, recall, F1-score, coefficient of determination, and root-mean-square error. Among the five models, the DT consistently outperforms others, achieving a maximum classification accuracy (96%). It also demonstrates strong interpretability under data-limited conditions. The novelty of the presented work lies in integrating model-specific feature importance with hydrochemical reasoning, revealing that salinity-related parameters serve as effective surrogate indicators for large-scale groundwater quality screening, while nutrients and hardness reflect localized anthropogenic and geogenic controls. The temporal analysis captures the evolving dynamics of groundwater quality over two decades. It is highlighting emerging risks despite partial improvements. Overall, the proposed model advances interpretable, data-driven groundwater assessment and provides actionable insights for early warning, sustainable monitoring, and policy-oriented water resource management in rapidly transforming river basins.
Harnessing Activated Sludge for the Treatment of Hydrothermal Liquefaction Wastewater: A Proof-of-Concept Study.
Li C, Wang J, Liu M … +6 more , Zheng Y, Kumar S, Umeda I, Mahata C, Norton J, Wang ZW
Water Environ Res · 2026 Feb · PMID 41700511 · Full text
Although hydrothermal liquefaction (HTL) is the leading technology in converting wet biomass into bioenergy, the treatment of its toxic-laden aqueous phase wastewater presents a major challenge on its path toward commerc...
Although hydrothermal liquefaction (HTL) is the leading technology in converting wet biomass into bioenergy, the treatment of its toxic-laden aqueous phase wastewater presents a major challenge on its path toward commercial viability. This study presents the first-ever assessment of sewage sludge-fed HTL wastewater (SS-HTLWW) treatment and toxic compound removal using municipal activated sludge (AS) by optimizing its cultivation condition. It was found that AS with optimized pretreatment can remove up to 91.2% of the soluble chemical oxygen demand (sCOD) in SS-HTLWW, of which up to 82% can be attributed to biological mineralization and adsorption of sCOD by AS. Conventional bioprocess optimization techniques, including overliming, elevated temperatures, and nutrient supplementation, were found to raise the maximum rate of sCOD utilization (R) of AS treatment by 44%, 67%, and 45%, respectively. The variation in the maximum degradation potential (D) after 23 days of treatment across all groups was negligible. Adjusting the SS-HTLWW dilution factor from 20× to 10× resulted in no significant difference in R or D values due to the counteracting effects of high substrate and inhibitor concentrations. Additionally, AS was able to eliminate almost all N-heterocycles, phenolic compounds, and organic acids found in SS-HTLWW. This suggested that AS can both survive in and mitigate the high level of toxicity associated with SS-HTLWW; however, the high levels of recalcitrant COD after treatment may require further attention before it can be adequately discharged. The insights gained from this study are poised to interest engineers and treatment plant operators in search of efficient strategies for SS-HTLWW management and the broader application of HTL.
Advances in the Distribution, Transport, and Transformation of PFAS in the Drinking Water System: From Source to Tap.
Yang H, He W, Li D … +5 more , Pan X, Li X, Zhu Q, Xiang H, Ouyang E
Water Environ Res · 2026 Feb · PMID 41699903 · Publisher ↗
Perfluoroalkyl and polyfluoroalkyl substances (PFASs) pose a significant threat to drinking water safety worldwide due to their extreme persistence, mobility, and documented adverse health effects. Currently, there is a...
Perfluoroalkyl and polyfluoroalkyl substances (PFASs) pose a significant threat to drinking water safety worldwide due to their extreme persistence, mobility, and documented adverse health effects. Currently, there is a lack of comprehensive reviews that systematically examine the behavior and transformation of PFAS across the drinking water system-from source to tap-incorporating recent advancements in precursor transformation, pipeline dynamics, and data-driven management. Our analysis synthesizes global data, revealing that PFASs are consistently detected in both source and finished water at nanogram-per-liter concentrations. Whereas conventional treatment technologies show minimal removal efficacy, advanced treatment processes such as granular activated carbon, anion exchange resins, and membrane filtration are constrained by high costs and material limitations. The review further highlights four key advancements: (1) the widespread occurrence of unidentified organic fluorides; (2) transformation pathways of PFAA precursors during oxidative treatment leading to recalcitrant byproducts; (3) dynamic PFAS retention-release mechanisms within distribution pipelines; and (4) machine learning-enabled tools for predicting contamination and optimizing treatment. These insights collectively enhance the understanding of PFAS persistence and transformation across the drinking water system, providing a scientific basis for improved regulation and control strategies. Finally, we propose current research challenges and suggest priority directions for future studies aimed at ensuring long-term drinking water security.
Emergence of Hypervirulent, Multidrug-Resistant Klebsiella pneumoniae Harboring magA in Coastal Water Sources: A Public Health Threat in Flood-Prone Communities.
Yousuf J, Aneesa PA, Mujeeb Rahiman KM … +1 more , Mohamed Hatha AA
Water Environ Res · 2026 Feb · PMID 41699885 · Publisher ↗
Coastal flooding increasingly compromises water security while accelerating antimicrobial resistance through enhanced microbial gene transfer. In light of growing concerns over the widespread occurrence of multidrug-resi...
Coastal flooding increasingly compromises water security while accelerating antimicrobial resistance through enhanced microbial gene transfer. In light of growing concerns over the widespread occurrence of multidrug-resistant Klebsiella pneumoniae in natural environments, we investigated the emergence and specific traits of classical and hypervirulent phenotypes of K. pneumoniae from domestic water sources in Cochin, India, a region frequently affected by flooding. Isolates were identified using 16S rRNA gene sequencing. Phenotypic characterization included the string test for hypermucoviscous traits, while antimicrobial susceptibility was determined via disc diffusion and microdilution. The ESBL production was confirmed using the combined disc diffusion test. Biofilm formation was quantified via the microtiter plate method with crystal violet staining. Finally, PCR was employed to detect key resistance (bla, bla, and blao) and virulence (magA) genes. Findings revealed that 95% of the isolates were multidrug resistant, with 75% confirmed as ESBLs and 42% displaying hypermucoviscous phenotype. Resistance was observed against critically important antibiotics, including carbapenems and colistin, with the highest Minimum inhibitory concentration (MIC) values against ceftazidime and ampicillin (> 256 μg/mL). Hypervirulent strains exhibited significantly higher resistance levels and formed thicker biofilms compared to classical strains (p = 0.01) and highly correlated with multiple antibiotic resistance index (ρ = 0.90, p < 0.001), suggesting enhanced environmental persistence. Both phenotypes harbored key resistance genes (bla, bla, and bla), indicating a high potential for severe hard-to-treat infections. These findings underscore the urgent need for continuous environmental surveillance and One Health interventions to combat the rise of environmental hypervirulent K. pneumoniae and protect public health in flood-prone regions.
Water Quality Assessment of an Urban River System: Temporal and Spatial Water Quality Trends in the Mula-Mutha River, Pune, India.
Nath S, Kumar DN, Vyas JN … +1 more , Chandra P
Water Environ Res · 2026 Feb · PMID 41693635 · Publisher ↗
River pollution is a significant global concern, as rivers have served as the foundation for the expansion of civilizations since time immemorial. The drastic increase in population, rapid industrialization, and urban ex...
River pollution is a significant global concern, as rivers have served as the foundation for the expansion of civilizations since time immemorial. The drastic increase in population, rapid industrialization, and urban expansion have caused deterioration of river ecosystems, adversely impacting agriculture, human health, and biodiversity. The Mula-Mutha River is an important river in Pune as it supplies water for irrigation and drinking purposes. This study aims to assess the physicochemical parameters of river water to determine its water quality (WQ) and examine how it has changed spatially over the years. Sampling was conducted at eight sites along the river, spanning from Khadakwasla to Daund, during the period 2019-2021. Key parameters analyzed included physicochemical parameters and the concentrations of various cations and anions. This paper discusses how spatial variations influence WQ, highlighting the contributing factors. The results show that WQ deteriorates downstream as the river enters the city where sewage discharge and effluents from various industries contribute to increasing pollution level. There was a variation in physicochemical parameters and ionic concentrations, with most parameters showing an increasing trend during the period 2019-2021. However, a significant reduction in pollution was observed at certain locations in 2021. Results indicate considerable deterioration in WQ, particularly at downstream sites. In 2019, WQI values exceeding 300 at Vitthalwadi, Bundgarden, and Kharadi classified the water as unsuitable for drinking. WQI values indicated an improvement in WQ during 2020 and 2021, reflecting the positive impact of reduced anthropogenic activities during the pandemic. Iron concentrations exceeded permissible limits at all locations except Khadakwasla, suggesting downstream iron enrichment influenced by anthropogenic processes. Chloride concentrations ranged from 15.6 to 536.57 mg/L, with most sites remaining within IS 10500 limits, except Daund (2019) and Bundgarden and Daund (2021), indicating localized salinity stress. Phosphate concentrations varied from 0.33 to 43.14 mg/L, with all sites except Khadakwasla exceeding the WHO permissible limit, posing a high risk of eutrophication. Elevated chloride and phosphate levels are attributed to anthropogenic inputs such as industrial effluents, sewage discharge, and agricultural runoff. Water quality index, sodium adsorption ratio, and residual sodium carbonate values were also calculated to determine the suitability of the river water for drinking and irrigation purposes. In 2019, Vitthalwadi, Bundgarden, and Kharadi recorded WQI values exceeding 300, indicating that the water was unsuitable for drinking. The water was found to be fit for irrigation except at Pargaon and Daund, which also showed noncompliance in other physicochemical parameters as well. WQI showed improvement in WQ during 2020 and 2021, indicating a positive impact of restrictions on anthropogenic activities during the pandemic. Overall, the findings highlight significant human-induced impacts on WQ and emphasize the need for continuous monitoring and effective management strategies to safeguard water resources for drinking and irrigation purposes.
Practical Indices for Minimizing External Carbon Demand in Mainstream ANAMMOX: A Sensitivity- and Regression-Based Approach.
Kim S, Gil K
Water Environ Res · 2026 Feb · PMID 41692686 · Publisher ↗
Mainstream anaerobic ammonium oxidation (ANAMMOX) offers a promising alternative to conventional nitrogen removal processes in municipal wastewater treatment. However, research has largely focused on its potential to red...
Mainstream anaerobic ammonium oxidation (ANAMMOX) offers a promising alternative to conventional nitrogen removal processes in municipal wastewater treatment. However, research has largely focused on its potential to reduce oxygen demand rather than external carbon requirements. This study compared the external carbon demand of mainstream ANAMMOX with that of anaerobic-anoxic-oxic (A2O) and partial denitrification/ANAMMOX (PD/A) processes. Stoichiometric ratios, validated in a laboratory-scale packed-bed biofilm reactor, were implemented in a simulation framework reflecting representative conditions in Korean wastewater treatment plants. A 5 × 5 × 3 × 3 simulation matrix evaluated external carbon demand and its sensitivity to sidestream ammonium concentration (SAC), mainstream ammonium concentration (MAC), mainstream total organic carbon concentration (MTC), and sidestream flow rate (SFR) through gradient-based analysis and regression modeling. Mainstream ANAMMOX reduced external carbon demand by up to ~10.8%-72.2% compared with A2O and ~3.7%-41.2% compared with PD/A, depending on influent loading conditions. SAC and MTC were identified as the dominant drivers of carbon reduction. Notably, higher MAC levels slightly diminished the relative carbon savings due to the increased external carbon requirement for polishing the stoichiometric nitrate byproduct. Three composite indices (sidestream effective nitrogen load index, total effective nitrogen load index, and sidestream contribution ratio [SCR]) were proposed, with SCR exhibiting the highest predictive accuracy. Although the absolute savings are site-specific, these findings suggest that mainstream ANAMMOX can substantially decrease reliance on external carbon sources, and the proposed indices provide practical tools for process evaluation and design optimization.
Valorization of Pretreated Salvinia molesta Biomass for Ciprofloxacin Biosorption: Kinetic Performance, pH-Dependent Mechanisms, and Circular Economy Implications.
Kochi LY, Rios RVS, Marques RZ … +2 more , Nakao LS, Gomes MP
Water Environ Res · 2026 Feb · PMID 41692584 · Full text
The valorization of pretreated waste Salvinia molesta biomass represents a sustainable and circular strategy to address both water contamination and biomass disposal. This study investigated the biosorption performance o...
The valorization of pretreated waste Salvinia molesta biomass represents a sustainable and circular strategy to address both water contamination and biomass disposal. This study investigated the biosorption performance of pretreated and powdered S. molesta biomass in controlled aqueous solutions of ciprofloxacin (CIP), a widely detected fluoroquinolone antibiotic, under environmentally relevant conditions. The biomass was characterized by a high cell wall fraction (~61%) and moderate protein and polyphenol content, offering a multifunctional surface for biosorption. Batch experiments were conducted to evaluate the effects of pH (4-8) and contact time (up to 60 min) on CIP removal (initial concentration = 1.5 μg/L). The maximum biosorption efficiency (~95%) occurred at pH 6, which aligned with the biomass's point of zero charge ( = 6.2) and the CIP zwitterionic speciation. Biosorption was rapid in the first 30 min, although equilibrium was rapidly reached within 30 min, consistent with the classical biosorption behavior of dead biomass at low concentrations. The kinetic model followed a pseudo-second-order trend, which was interpreted empirically rather than mechanistically, reflecting surface-controlled adsorption dynamics. Pearson correlations revealed that the protein and polyphenol contents were positively associated (r > 0.85) with biosorption at pH 6-7, highlighting a multi-mechanistic interaction involving electrostatic, hydrogen bonding, and π-π interactions. These findings suggest that S. molesta is a naturally abundant, low-cost biosorbent suitable for decentralized water remediation, particularly in small-scale or proof-of-concept systems using model aqueous matrices, with potential applications in passive treatment units and community-based sanitation systems. Future studies should evaluate isotherm behavior, thermodynamic parameters, and the regeneration potential of the biosorbent to determine scalability under real wastewater conditions.
Macrophyte Extracts Promote the Growth of the Microbial Community Associated With Microcystis aeruginosa Alleviating Allelopathic Effects.
Silva L, Santos AA, Azevedo SMFO … +1 more , Pacheco ABF
Water Environ Res · 2026 Feb · PMID 41689278 · Full text
Macrophytes such as Pistia stratiotes and Pontederia crassipes can release allelopathic compounds and reduce cyanobacteria biomass. Cyanobacterial cells interact with heterotrophic bacteria, which contribute to nutrient...
Macrophytes such as Pistia stratiotes and Pontederia crassipes can release allelopathic compounds and reduce cyanobacteria biomass. Cyanobacterial cells interact with heterotrophic bacteria, which contribute to nutrient uptake and antioxidative responses, among other functions. However, the role of microbial communities in allelopathic interactions between macrophytes and cyanobacteria remains unexplored. We investigated how the bacterial community associated with Microcystis aeruginosa influences the effects of aqueous macrophyte extracts. Both extracts inhibited cyanobacterial growth and photosynthetic activity (99% for P. stratiotes and 55% for P. crassipes) while increasing bacterial abundance (threefold). The composition of the bacterial communities stimulated by extracts shifted: whereas original cultures were rich in Methyloversatilis and Rhodobacter, the P. stratiotes extract promoted the growth of Shinella, Flavobacterium, and Comamonadaceae, and the P. crassipes extract favored Enterobacterales. When these stimulated communities were reintroduced into M. aeruginosa cultures, allelopathic inhibition was reduced (40% for P. stratiotes and 12% for P. crassipes). We concluded that the growth of the associated microbiota attenuated the allelopathic effects, partially preserving cyanobacterial cells. Bacterial groups favored by the treatments may participate in allelochemical degradation and antioxidant protection or activate other types of metabolism beneficial to cyanobacteria, mitigating the harmful effects of the extracts. These results highlight the importance of considering the role of microbial communities in cyanobacterial allelopathic interactions.
Enhanced Phosphorus Removal From Municipal Wastewater via Cotreatment of Mine Drainage During Primary Clarification.
Roman B, Cravotta CA, Spellman CD … +3 more , Strosnider WHJ, Goodwill JE, Tasker T
Water Environ Res · 2026 Feb · PMID 41684349 · Full text
Cotreatment of mine drainage (MD) in existing wastewater treatment plants (WWTPs) could provide treatment benefits for both waste streams. The alkalinity that is innate to most WW may be sufficient to neutralize MD acidi...
Cotreatment of mine drainage (MD) in existing wastewater treatment plants (WWTPs) could provide treatment benefits for both waste streams. The alkalinity that is innate to most WW may be sufficient to neutralize MD acidity, elevating pH and correspondingly decreasing concentrations of dissolved metals. Additionally, PO in WW interacts with Fe and Al in MD and is removed from solution, potentially decreasing the need for enhanced biological treatment or chemical precipitation techniques. However, there are concerns about how adding MD to a WWTP may impact the treatment efficiency of the WWTP. Hence, the objective of this study was to determine the impact of AMD addition on the kinetics of BOD removal, in addition to the extent of metals, acidity, and PO removal when WW and MD were mixed in a bench-scale primary clarifier. MD was mixed with primary influent WW in 10:90 and 40:60 MD:WW ratios and allowed to settle for 2 h before the supernatant was transferred to BOD respirometers. The pH remained circumneutral 2 h after mixing, ranging from 7.44 to 8.27 for 10% MD and 6.66 to 7.36 for 40% MD. The BOD oxidation rate was unaffected by MD addition, with first-order kinetic rates ranging from 0.50 to 0.77 day for raw WW, 0.54 to 0.97 day for 10% MD, and 0.45 to 0.95 day for 40% MD. PO removal increased linearly with the molar ratio of ([Fe] + [Al])/[PO-P] for the conservative mixture of raw WW and MD and reached > 99% removal when (([Fe] + [Al])/[PO-P]) > 2. Overall, this work establishes a practical framework for leveraging mine drainage chemistry within conventional wastewater primary treatment to enhance phosphorus capture without compromising downstream biological performance. The approach offers a scalable pathway for utilities to turn a problematic influent into a controllable unit-process benefit, supporting tighter nutrient limits with minimal new infrastructure and chemical inputs.
A Comprehensive Review of MP Pollution in Global Rivers: Distribution Patterns and Fluvial Transport Dynamics.
Rangari GH, Lade AD, Ghare AD
Water Environ Res · 2026 Feb · PMID 41684336 · Publisher ↗
Microplastics (MPs) have a ubiquitous presence in our environment, and their abundance, particularly in fluvial systems, has been documented in most rivers worldwide over the last decade. Rivers are critical carriers of...
Microplastics (MPs) have a ubiquitous presence in our environment, and their abundance, particularly in fluvial systems, has been documented in most rivers worldwide over the last decade. Rivers are critical carriers of almost 70%-80% of the plastic waste that reaches the oceans from land-based sources, and MPs have become a major pollutant found in the riverine sediments. This article comprehensively reviews the available studies on the MP pollutants in riverine sediments across global rivers. A synthesis of continent-wise characteristics of MPs in river sediments, including primary sources, shape and size, polymer types, and concentration levels, based on statistical parameters, is presented. MP concentrations show a strong gradient across continents, with the highest levels detected in Africa, followed by Asia, South America, Europe, North America, and Australia. Globally, the major primary sources of MPs in river sediments include wastewater treatment plants, industrial discharges, textile and garment processing, fishing-related activities, and mismanaged municipal waste, although their relative contributions indicate substantial geographic variation. Across all continents, the occurrence of fibers and fragments is significant, and PE, PP, PS, PET, and PA emerge as the most commonly found polymers in the riverbed. Additionally, inferences are drawn from the available studies on the threshold, movement, and deposition processes of MP pollutants in river systems. Due to lower densities (particularly for PP, PE, and ABS) and decreased bed friction, MPs commence movement at lower shear stresses compared to the natural sediments of equal size. The Corey shape factor significantly influences the incipient motion thresholds, but its effect depends on particle orientation and friction. The inclusion of static friction and hydraulic roughness yields a more accurate threshold model, enabling a modified Shields framework that predicts MP incipient motion more accurately than classical sediment-based curves. Major gaps in the literature regarding the need for reliable estimates of critical bed shear stress for various MP particles and the effect of fluvial factors, such as seepage and vegetation, on MP transport are identified.
Techno-Economic and Life Cycle Assessment of Anaerobic/Aerobic Integrated Biosystem for Threefold "Biogas, Biochar, and Treated Effluent" Benefits.
Zidan A, Anang S, Ibrahim MG … +1 more , Nasr M
Water Environ Res · 2026 Feb · PMID 41681013 · Publisher ↗
Although sequential anaerobic/aerobic processes have recently emerged as viable domestic wastewater treatments, their performance under higher organic loading rates (OLRs) requires further investigation to meet economic...
Although sequential anaerobic/aerobic processes have recently emerged as viable domestic wastewater treatments, their performance under higher organic loading rates (OLRs) requires further investigation to meet economic and sustainability benchmarks. This study evaluates an integrated up-flow anaerobic sludge blanket (UASB) reactor followed by a downflow hanging sponge (DHS) system, comparing its techno-economic performance to a standalone UASB unit. Chemical oxygen demand (COD) mass balance analysis revealed that 32%-54% of influent COD was converted to methane (CH) and 17%-22% to sludge, yielding 205-255 L CH per kg of COD removed. The subsequent DHS unit provided robust polishing, achieving total removal efficiencies of 62%-94% for COD, 75%-95% for biochemical oxygen demand (BOD), 81%-94% for total suspended solids (TSS), 28-72% for total Kjeldahl nitrogen (TKN), and 63-100% for NH -N at an OLR of 0.84-5.43 kg COD/(m·d). Furthermore, sludge pyrolysis produced a nutrient-rich, calcite-composed biochar (yield: 0.54 g/g dry sludge) suitable for soil amendment. Economic analysis, incorporating biogas and biochar sales, carbon credits, and pollutant shadow pricing, confirmed the system's feasibility. As such, the profitability criteria were estimated as a payback period of 5.9 years, an internal rate of return (IRR) of 11.0%, and a net present value (NPV) of 3485 US$. Given the superior life cycle assessment (LCA) results regarding carbon footprint and ecosystem health, this UASB/DHS/pyrolysis strategy warrants further research into biochar's role in enhancing biogas and digestate quality throughout the project lifetime.
Dynamic Simulation and Causal Mechanisms of Eutrophication in Irregular Shallow Urban Lakes Based on Numerical Models.
Guo B, Zhang Q, Hou Y … +5 more , Yu P, Qin M, Liu C, Zhang M, Gao X
Water Environ Res · 2026 Feb · PMID 41680077 · Publisher ↗
Urban irregular shallow lakes are characterized by sinuous shorelines and substantial variations in water depth, which promote the accumulation of pollutants and nutrients. The interaction between nonpoint source polluti...
Urban irregular shallow lakes are characterized by sinuous shorelines and substantial variations in water depth, which promote the accumulation of pollutants and nutrients. The interaction between nonpoint source pollution and internal pollution leads to rapid and frequent occurrences of eutrophication, complicating the prevention and remediation endeavors. To explore the mechanisms and causes of eutrophication under such circumstances, a two-dimensional hydrodynamic-water quality coupled model of Meijiang Lake was established using the MIKE 21 numerical model. A series of extensive field measurements conducted from April to September 2024 were utilized for model parameter calibration and validation. By simulating the spatiotemporal distribution of lake flow fields and key water quality parameters, such as total nitrogen, total phosphorus, and chlorophyll a, under both inflow and stagnant conditions, and by introducing the lake shape index (LSI) to quantify lake morphology, this study systematically analyzed the influence of lake shape on hydrodynamic conditions and the risk of eutrophication. The results suggest that the model demonstrates high reliability (Nash coefficient close to 0.9). Simulations reveal notable shape-dependent hydrodynamic effects. Lake A, with a regular shape and an LSI of 1.9, maintains optimal water quality owing to limited external inputs and strong water exchange capacity. Lake C, also with a regular shape and an LSI of 1.7, attains moderate water quality despite relatively high external inputs, benefiting from its robust exchange capacity. Lake B, featuring a tortuous morphology and an LSI of 4.65, exhibits low flow velocity and poor water exchange capacity. Coupled with high external inputs, this results in the formation of local stagnant areas with severe nutrient accumulation, rendering it a high-risk area for algal bloom outbreaks. Correlation analysis and quantitative results further demonstrate that chlorophyll a concentration is positively correlated with LSI, water temperature, and total phosphorus and negatively correlated with flow velocity and dissolved oxygen. With each one-unit increase in LSI, the lake's average flow velocity decreases by 35%, while the average eutrophication level rises by approximately 4.1% (range: 1%-7%). This confirms that lake morphology is one of the key factors regulating differences in eutrophication, providing a scientific basis for differentiated management and ecological restoration of urban landscape lakes.
Exergy Analysis for Evaluating the Performance of an Integrated Leachate Treatment System.
Villamizar S, Maturana-Cordoba A, Mejía-Marchena R … +2 more , Soto-Verjel J, Soto-Vergel A
Water Environ Res · 2026 Feb · PMID 41674459 · Publisher ↗
Exergy analysis provides a unified framework for assessing environmental, technical, and economic aspects in energy terms, enabling the identification of irreversibilities that reduce process efficiency. In wastewater tr...
Exergy analysis provides a unified framework for assessing environmental, technical, and economic aspects in energy terms, enabling the identification of irreversibilities that reduce process efficiency. In wastewater treatment, its application remains limited, focusing on municipal effluents and chemical exergy derived from chemical oxygen demand. This study proposes an advanced exergy analysis model for wastewater treatment, structured in three phases: (i) system data, (ii) exergy analysis, and (iii) optimization through exergoenvironmental, exergoeconomic, and exergotechnical indicators, statistically assessed using the desirability function approach (DFA). The model was validated using a case study of a leachate treatment system that combined coagulation-flocculation, three photo-Fenton configurations, and activated sludge. The highest desirability (0.59) in exergy terms for the pretreatment was achieved with 1 g L iron chloride at pH 5, while DFA was 0.74 in the photo-Fenton process involved pretreated leachate with residual iron (0.08 g L of iron) and a single 2.5 g L dose of hydrogen peroxide followed by biological treatment. Irreversibilities were greatest in the biological stage due to electricity demand followed by influent composition, reagent consumption, and sludge generation. The model offers robust criteria for optimizing treatment design and supports the achievement of Sustainable Development Goals 6, 11, and 12.
Smart Water Management: Role of IoT, AI, and Machine Learning in Water Quality Monitoring.
Dutta P, Sarma S
Water Environ Res · 2026 Feb · PMID 41645796 · Publisher ↗
Water quality deterioration has intensified the need for rapid and accurate assessment using modern monitoring approaches. Conventional laboratory-based techniques often suffer from delayed analysis and low sampling freq...
Water quality deterioration has intensified the need for rapid and accurate assessment using modern monitoring approaches. Conventional laboratory-based techniques often suffer from delayed analysis and low sampling frequency, limiting timely decision-making. Key quantitative parameters-including pH (optimal 6.5-8.5), dissolved oxygen (DO > 5 mg/L for aquatic health), turbidity (< 1-5 NTU for drinking-water standards), electrical conductivity (250-1500 μS/cm depending on source), and Water Quality Index (WQI < 50 indicating good quality and > 100 reflecting poor conditions)-serve as essential indicators of ecosystem and human health. Recent advancements in Internet of Things (IoT) sensors, artificial intelligence (AI), and machine learning (ML) have enabled high-frequency measurements, predictive forecasting, anomaly detection, and enhanced early warning capabilities. IoT-enabled multiparameter sensing combined with ML models such as random forests, gradient boosting, and deep neural networks significantly improve accuracy in pollutant prediction and trend analysis. This review synthesizes the latest progress in IoT-, AI-, and ML-driven water quality monitoring, outlines quantitative improvements reported in recent literature, and highlights remaining technical, economic, and governance challenges influencing large-scale deployment.
Enhanced the Treatment of Seafood Processing Wastewater Using the Anaerobic-Anoxic-Oxic (AAO) Process With Granular Sludge.
Cuong TM, Dan NH, Hang TTT … +3 more , Le Luu T, Scheynen J, Dries J
Water Environ Res · 2026 Feb · PMID 41645540 · Publisher ↗
Seafood processing wastewater contains high concentrations of organics and nutrients that need to have an effective solution. This study aims to explore the use of granular sludge in seafood wastewater treatment using an...
Seafood processing wastewater contains high concentrations of organics and nutrients that need to have an effective solution. This study aims to explore the use of granular sludge in seafood wastewater treatment using anaerobic-anoxic-aerobic (AAO) process. The results showed that the granular sludges were successfully cultivated from the traditional activated sludge sources. The bioreactor demonstrated robust treatment performance, achieving a high chemical oxygen demand (COD) removal efficiency exceeding 93%, total nitrogen (TN) removal ranging from 56.6% to 68.6%, and ammonium removal (NH -N) of 80% to 88.57%. However, total phosphorus (TP) removal efficiency was relatively moderate at 47.36% ± 10.33%. Metagenomic analysis (16S rRNA) revealed a diverse and evenly distributed microbial community within the granular sludge. In anaerobic granular sludge, the dominant phylum was Bacillota (45.3%), followed by Thermodesulfobacteriota (18.2%) and Synergistota (11.24%), with minor contributions from Campylobacterota (7.58%), Chloroflexota (3.98%), and Bacteroidota (3.6%), alongside other less abundant phyla (10.1%). Anoxic granular sludge exhibited a shift, with Pseudomonadota (32.87%) and Thermodesulfobacteriota (25.08%) dominating, while Bacillota (11.95%), Bacteroidota (7.9%), and Chloroflexota (4.1%) contributed less, and other phyla comprised 18.21%. For aerobic granular sludge, Pseudomonadota represented the most prevalent phylum (42.21%), followed by Thermodesulfobacteriota (14.94%) and Bacillota (14.87%), with lower abundances of Bacteroidota (7.74%) and Chloroflexota (4.91%), while other phyla accounted for 15.42%.
Clarias macrocephalus Aquaculture Wastewater Treatment Using Bacterial Attachment Media From Bentonite and Acrylic Acid.
Ho LB, Le HT, Huynh AT
Water Environ Res · 2026 Feb · PMID 41644482 · Publisher ↗
The development of effective and environmentally friendly bacterial attachment media remains a challenge in aquaculture wastewater treatment, particularly for systems with high organic loading such as Clarias macrocephal...
The development of effective and environmentally friendly bacterial attachment media remains a challenge in aquaculture wastewater treatment, particularly for systems with high organic loading such as Clarias macrocephalus ponds. In this study, a bentonite-acrylic acid hydrogel was synthesized by gamma irradiation and evaluated as a bacterial attachment medium for aquaculture wastewater treatment. The effects of composition ratio and irradiation dose on gel-forming ability, swelling behavior, and solubility were investigated to determine optimal preparation conditions. The hydrogel prepared at a bentonite-to-acrylic acid ratio of 10:1 (g/mL) and an irradiation dose of 25 kGy exhibited favorable gel properties and structural stability, making it suitable for bacterial immobilization. Two bacterial strains (B4 and B5) demonstrated strong adhesion to the attachment media and stable immobilization behavior. When applied to wastewater treatment, the combined system achieved high removal efficiencies of 99.44% COD, 99.40% BOD₅, 93.20% TP, 98.14% ammonia, 88.39% SS, and 85.21% color meeting the discharge limits of Vietnamese standards. These results indicate that the bentonite-acrylic acid hydrogel synthesized by irradiation is a promising attachment medium for enhancing biological treatment efficiency in aquaculture wastewater systems.
A Hydro-Biogeochemical Tracing Method for Soil-Groundwater Organic Contamination in Industrial Sites: Development and Validation of a Micro-Disturbance System.
Kang S, Xu T, Zha E … +3 more , Sun Y, Xia F, Wang J
Water Environ Res · 2026 Feb · PMID 41640212 · Publisher ↗
The heterogeneity of soil and groundwater media, combined with the complexity of contaminant hydro-biogeochemical behavior, limits the effectiveness of traditional high-disturbance, low-density methods, such as drilling,...
The heterogeneity of soil and groundwater media, combined with the complexity of contaminant hydro-biogeochemical behavior, limits the effectiveness of traditional high-disturbance, low-density methods, such as drilling, for characterizing contaminant transport and transformation processes. To address this, we developed a micro-disturbance detection and data interpretation method based on multiprocess coupling theory, focusing on key hydro-biogeochemical processes of organic pollutants. Validation was conducted at a petroleum-contaminated site in North China using a phased approach that integrated micro-disturbance screening with drilling verification. The results showed that the micro-disturbance screening successfully delineated a plume of approximately 1542 m, consistent with shallow soil exceedances and groundwater contamination, thereby demonstrating a strong correlation between surface gas anomalies and subsurface biogeochemical processes. This study enhances source-plume delineation capability, provides technical support for tracing contaminant biogeochemical processes, and offers a scientific basis for implementing remediation strategies such as enhanced natural attenuation.
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