Water Environment Research[JOURNAL]
Sun
200 papers
Geochemical Behavior of Rare Earth Elements in Saline and Salty Springs From a Carbonate-Evaporite Aquifer in the Northeastern Sichuan Basin, China.
Guo J, Jing Y, Wang C … +1 more , Wang M
Water Environ Res · 2026 Apr · PMID 42025588 · Publisher ↗
Rare earth elements (REEs) in saline groundwater are effective tracers of hydrogeochemical processes in deep carbonate-evaporite aquifer systems. This study examines the hydrochemistry, distribution, fractionation, and a...
Rare earth elements (REEs) in saline groundwater are effective tracers of hydrogeochemical processes in deep carbonate-evaporite aquifer systems. This study examines the hydrochemistry, distribution, fractionation, and aqueous speciation of REEs in brackish, saline, and salty springs from the northeastern Sichuan Basin, China. Spring waters are dominated by Na-Cl and Cl·SO-Na facies, with TDS up to 82.9 g/L, mainly controlled by Triassic evaporite dissolution and deep brine mixing along faulted anticlines. Dissolved REE concentrations are low (ΣREE = 0.096-0.314 μg/L) and decrease with increasing salinity and pH. NASC-normalized patterns show consistent MREE-HREE enrichment and pronounced positive Eu anomalies in deep, reducing thermal waters. Geochemical modeling indicates that REEs are predominantly stabilized as carbonate complexes, with LnCO and Ln (CO) accounting for over 90% of dissolved species. These results demonstrate that tectonically driven deep circulation, redox conditions, and carbonate complexation jointly regulate REE behavior in saline groundwater systems.
Enhanced Removal of Tetracycline Hydrochloride via Synergistic Mechanisms Using CTAB-Modified Bentonite-Supported Zerovalent Aluminum in Aqueous Solution.
Liu P, Yan J, Gao B … +1 more , Yang B
Water Environ Res · 2026 Apr · PMID 42025533 · Publisher ↗
This study developed a composite material using organically modified bentonite as a carrier for zerovalent aluminum (ZVAl) to create an integrated adsorption-oxidation-reduction system for treating tetracycline hydrochlo...
This study developed a composite material using organically modified bentonite as a carrier for zerovalent aluminum (ZVAl) to create an integrated adsorption-oxidation-reduction system for treating tetracycline hydrochloride (TCH) wastewater. The unique lamellar structure and abundant hydrophobic functional groups of organic bentonite effectively prevent ZVAl particle agglomeration, while partially isolating ZVAl from water contact, thus minimizing side reactions and significantly enhancing ZVAl stability. Through systematic optimization, the optimal conditions were determined as follows: 1.09 g dosage, 42.08% loading rate, pH 3.39, and 50°C reaction temperature. Under these conditions, TCH achieved remarkable removal efficiencies of 96.06%, representing a 40.3% improvement over pure ZVAl. Kinetic and isotherm analyses confirmed the process follows pseudo-second-order kinetics and the Freundlich model. Free radical quenching experiments confirmed that ·OH radicals are the primary oxidative species. In conclusion, organic bentonite loaded with ZVAl represents an effective and promising material for the treatment of recalcitrant organic wastewater.
Fluoride Sources and Enrichment Mechanisms in a Coastal Plain Under the Influence of Seawater Intrusion.
Hao X, Liu Y, Yang P … +2 more , Chen Z, Zhou Y
Water Environ Res · 2026 Apr · PMID 42023557 · Publisher ↗
Fluoride (F) enrichment in coastal groundwater poses a persistent threat to drinking water safety, yet its controlling mechanisms under seawater intrusion remain incompletely understood, particularly in northern coastal...
Fluoride (F) enrichment in coastal groundwater poses a persistent threat to drinking water safety, yet its controlling mechanisms under seawater intrusion remain incompletely understood, particularly in northern coastal China. This study integrates hydrogeochemical analysis, Bayesian-optimized random forest modeling, and positive matrix factorization (PMF) to elucidate the sources and enrichment processes of F in shallow groundwater of the Qinhuangdao coastal plain. Results demonstrate that elevated F concentrations are not directly driven by seawater mixing. Instead, maximum F levels occur under mild seawater intrusion, while severely intruded zones exhibit lower and less variable F concentrations. PMF results further reveal that F enrichment is dominated by geogenic sources related to fluorite dissolution, accompanied by contributions from silicate weathering and evaporation-leaching processes. Geochemical evidence indicates that seawater intrusion indirectly promotes F release by increasing groundwater alkalinity, enhancing ionic strength, and reducing Ca activity through carbonate precipitation, thereby facilitating fluorite dissolution. However, end-member mixing analysis confirms that the direct contribution of seawater-derived F is limited. These findings clarify the nonlinear relationship between seawater intrusion intensity and groundwater F enrichment and emphasize that seawater intrusion acts primarily as an amplifying factor rather than a primary source of fluoride. This study provides a process-based understanding of fluoride enrichment in coastal aquifers and offers scientific guidance for groundwater management and drinking water risk mitigation in seawater-intruded coastal regions.
Utilization of Chalcone for Targeted Removal of Azo Dye From Wastewater.
Yorur Goreci C, Isik B
Water Environ Res · 2026 Apr · PMID 42023521 · Full text
In this study, a chalcone derivative (BrBP-Ch), designed as a small molecule adsorbent, was evaluated for the removal of Congo red (CR) dye from aqueous solutions. The adsorbent was characterized using FTIR-ATR, H NMR, C...
In this study, a chalcone derivative (BrBP-Ch), designed as a small molecule adsorbent, was evaluated for the removal of Congo red (CR) dye from aqueous solutions. The adsorbent was characterized using FTIR-ATR, H NMR, C NMR, HRMS (Q-TOF), SEM, XRD, and zeta potential. Optimal conditions were determined as a dosage of 0.04 g/10 mL, a pH of 4, and a contact time of 90 min. The raw data obtained from the adsorption were applied to two- and three-parameter isotherms, and it was observed that the most suitable model was the Sips and Langmuir. The values from the Sips and Langmuir were calculated as 10.13 mg/g and 9.819 mg/g, respectively. Kinetic data were applied to pseudo-first order, pseudo-second order, intraparticle diffusion, and Boyd models. It was seen that the adsorbent could be reused repeatedly for up to five cycles. The findings reveal that small molecule adsorbents are a promising alternative for wastewater treatment.
Implication of Rheological and Thermal Properties of Sludge for Energy Optimization in a Sludge Treatment Train Incorporating Thermal Hydrolysis and Anaerobic Digestion.
Saha PR, Chen X, Prabakar S … +1 more , Choi H
Water Environ Res · 2026 · PMID 42017602 · Publisher ↗
Thermal hydrolysis process (THP), as an emerging pretreatment step for anaerobic digestion process (ADP), improves sludge biodegradability and thus solids volume reduction and energy recovery. However, a lack of integrat...
Thermal hydrolysis process (THP), as an emerging pretreatment step for anaerobic digestion process (ADP), improves sludge biodegradability and thus solids volume reduction and energy recovery. However, a lack of integrated data on the changes in sludge properties across the entire treatment train hinders the design of key energy-efficient units. To address this data gap, this study reports the physical and chemical properties of sludge sampled over 12 months at five crucial locations within a sludge treatment train. Along with measurements at 20°C, dynamic viscosity and thermal conductivity were measured based on actual temperature range up to 100°C. Detailed rheological modeling was also conducted using the Herschel-Bulkley equation to assess yield stress and flow index across the THP, cooling heat exchangers (CHEs), and ADP. Results showed that THP reduces yield stress from 34.3 to 8.0 Pa through CHEs and ADP and increases thermal conductivity by disrupting flocs and releasing bound water. ADP further lowered viscosity, shaping sludge into a more fluid state. Notably, a critical divergence was observed at operational temperature (70°C) while dynamic viscosity decreased remarkably (20%-50%), and thermal conductivity remained stable. Overall, it was proven that property changes are governed not only by total solids content but also by the fundamental restructuring of the physical and chemical composition (suspended vs. dissolved solids, organic vs. inorganic fractions), which are the primary drivers altering the thermal and rheological properties of sludge, deviating significantly from water in a predictable and quantifiable manner. This study provides the first stage-resolved analysis linking the changes in the physicochemical properties to real operational temperature regimes across a full-scale sludge treatment train. The knowledge provides valuable insights for design and operation of sludge treatment systems to reduce energy demand and improve sustainability.
Posttreatment of Effluents From UASB Reactors Through Vertical Flow Wetlands Coupled With Coagulant-Free Double Filtration for Safe Water Reuse.
Machado MFB, da Silva CP, Dos Santos Matos DG … +1 more , de Campos SX
Water Environ Res · 2026 Apr · PMID 42003683 · Publisher ↗
Water reuse is increasingly adopted to address global water scarcity, particularly for nonpotable applications. This study evaluated a pilot-scale treatment train consisting of a vertical flow constructed wetland (VFCW)...
Water reuse is increasingly adopted to address global water scarcity, particularly for nonpotable applications. This study evaluated a pilot-scale treatment train consisting of a vertical flow constructed wetland (VFCW) followed by sequential double filtration (DF) consisting of a sand filter followed by activated carbon and clinoptilolite media as posttreatment of domestic wastewater previously treated in an upflow anaerobic sludge blanket (UASB) reactor. The system was operated under three hydraulic loading rates (200, 400, and 600 mm/day), corresponding to organic loading rates of 26.8 to 94.9 g COD/m·day. The VFCW provided effective polishing of organic matter, achieving COD and BOD removals of up to 78% and 87%, respectively, relative to the UASB effluent, while additional total suspended solids removal ranged from approximately 25% at low and intermediate loadings to about 11% at the highest loading rate. Total nitrogen removal remained moderate and variable (~30%-65%), reflecting the predominance of aerobic conditions and limited denitrification potential within the wetland. Phosphorus removal in the VFCW was variable, with low efficiencies under low and high loadings (~14%-18%) and evidence of phosphorus remobilization under intermediate loading conditions. Microbial attenuation in the VFCW resulted in Escherichia coli removals of 90%-96% at low to intermediate hydraulic loads, with reduced performance at the highest loading rate. In contrast, the downstream DF consistently provided additional E. coli removal exceeding 99%, yielding final effluent concentrations on the order of 10 CFU/100 mL and complying with international reuse guidelines. Overall, the integrated VFCW-DF configuration functioned as a robust multibarrier system, enhancing operational reliability and demonstrating the potential of combined nature-based and low-cost filtration processes for decentralized wastewater reuse. Importantly, the results demonstrate that coagulant-free double filtration acts as a stabilizing barrier, transforming variable wetland performance into consistent and reuse-compliant effluent quality.
Engineered Geopolymer Nanocomposites for Sustainable Wastewater Treatment.
Sujitha VS, Vaishnavi M, Janani V … +1 more , Subramani R
Water Environ Res · 2026 Apr · PMID 42003362 · Publisher ↗
The increasing need for bioenergy has resulted in greater attention to sustainable wastewater management concepts. These demands have enhanced the review of novel adsorbent and photocatalytic materials for sustainable wa...
The increasing need for bioenergy has resulted in greater attention to sustainable wastewater management concepts. These demands have enhanced the review of novel adsorbent and photocatalytic materials for sustainable wastewater treatment technologies. The study systematically reviews the geopolymer-based nanocomposites as a multifunctional material for wastewater treatment. The synthesis techniques, structural modification, adsorption processes, photocatalytic degradation pathways, antimicrobial properties, and prospects for recovering nutrients are considered. The performance of the developed adsorbents is compared with conventional adsorbents in terms of the removal performance, stability, generation capacity, and life cycle influence. The issue of geopolymer nanocomposites is discussed in regard to sustainability as it concerns carbon footprint reduction, incorporation of the aspects of the circular economy, resource recovery, and economic sustainability of the system. Critical concerns such as scalability, long-term stability, and membrane integration are discussed. The adsorption capacities for Pb removal are up to 95-450 mg g and dye removal efficiencies of up to 85%-95% are obtained when geopolymer matrices are functionalized with metal oxide or carbon-based nanomaterials. The research sheds light on the implementation of the advanced geopolymer technologies in wastewater treatment by covering the main issues and opportunities.
Chip-Based Digital PCR Approach for Improved SARS-CoV-2 Quantification for Endemic Wastewater Surveillance.
Jo Y, Choi S, Lee DG
Water Environ Res · 2026 Apr · PMID 41999093 · Publisher ↗
The COVID-19 pandemic has revealed the importance of wastewater-based epidemiology (WBE) due to its advantages over traditional surveillance systems. However, low viral prevalence poses a significant challenge for reliab...
The COVID-19 pandemic has revealed the importance of wastewater-based epidemiology (WBE) due to its advantages over traditional surveillance systems. However, low viral prevalence poses a significant challenge for reliable detection of SARS-CoV-2 in endemic wastewater settings. This study aimed to improve detection sensitivity of SARS-CoV-2 by applying the chip-based digital PCR (dPCR) approach targeting the CDC N1 and N2 genes to wastewater samples processed with a combined magnetic bead concentration method during a low-prevalence period in South Korea. Here, the evaluation results using dPCR combined with magnetic bead concentration showed higher viral loads and lower variability compared to the commonly used electronegative filtration method. Comparative analysis of the dual-target N1 + N2 and E-Sarbeco assays revealed that the N1 + N2 assay yielded significantly higher concentrations (4.73 ± 0.19 log GC/L) than the E gene assay (4.27 ± 0.25 log GC/L) in dPCR analysis (p < 0.01). PMMoV normalization increased the Pearson correlation coefficient between SARS-CoV-2 concentrations and clinical case data from R = 0.1 to R = 0.31; however, this was not statistically significant. These findings contribute to enhancing detection sensitivity for SARS-CoV-2 wastewater surveillance in endemic settings.
Analysis of the Chemical Characteristics of Groundwater and the Impact of Seawater Intrusion and Anthropogenic Pollution in the Jiaodong Peninsula Region.
Gong Z, Wang Y, Hu J … +5 more , Cui J, Kang R, Ai H, Dai Y, Li H
Water Environ Res · 2026 Apr · PMID 41992413 · Publisher ↗
The Jiaodong Peninsula, a representative coastal region in eastern China, relies heavily on groundwater to sustain its socioeconomic development. The Jiaodong Peninsula is subject to the complex interactions among geolog...
The Jiaodong Peninsula, a representative coastal region in eastern China, relies heavily on groundwater to sustain its socioeconomic development. The Jiaodong Peninsula is subject to the complex interactions among geological conditions, seawater intrusion, and intensive human activities; however, traditional methods struggle to distinguish between these sources, highlighting the need for quantitative assessments of pollution source attribution in the region. To investigate this, we systematically collected and analyzed 54 groundwater samples from Qingdao City, a typical case study in the southern Jiaodong Peninsula. A multi-methodological approach-including descriptive statistics, Piper trilinear diagrams, Gibbs plots, ion ratios, and the absolute principal component score-multiple linear regression (APCS-MLR) receptor model-was employed to characterize the hydrogeochemical evolution and quantify source contributions. Results indicate that the groundwater is generally weakly alkaline, with a mean total dissolved solids (TDS) concentration of approximately 1170 mg/L. While freshwater predominates inland, significant salinization is evident in coastal zones. Driven by seawater intrusion, the hydrochemical facies transition from HCO -Ca type to Cl-Na type along the inland-to-coastal gradient, exhibiting typical coastal groundwater evolutionary signatures. Furthermore, elevated NO concentrations highlight a substantial anthropogenic footprint. Ion ratio analyses suggest that the groundwater chemistry is co-governed by rock weathering, seawater intrusion, cation exchange, and agricultural/domestic pollution. Quantitative source apportionment via the APCS-MLR model revealed that (1) Factor 1 (halite dissolution and seawater intrusion) explained 86.4% of the variance in Na concentrations, 81.2% of the variance in Cl concentrations, and 72.5% of the variance in TDS; (2) Factor 2 (natural water-rock interaction and salinization processes) explained 88.9% of the variance in Ca concentrations and 75.8% of the variance in total hardness; and (3) Factor 3 (anthropogenic pollution) explained 84.3% of the variance in NO concentrations and 91.5% of the variance in NO concentrations, while also explaining 42.6% of the variance in SO concentrations. This study underscores that while natural processes remain fundamental, the superposition of seawater intrusion and human activities significantly reshapes the hydrochemical environment. These findings, derived from this representative case study in Qingdao, provide a scientific basis for groundwater resource protection and the mitigation of seawater intrusion and nitrate pollution across similar coastal settings in the Jiaodong Peninsula.
Oil Spill Cleanup in the Marine Environment: How to Use Current Technology to Restore Oil Spills.
Sallal AK
Water Environ Res · 2026 Apr · PMID 41991328 · Publisher ↗
Oil spills pose a serious danger to marine ecosystems both offshore and on land. Various methods exist for removing oil from the water, and this article will cover the basics of four of them: physical, chemical, thermal,...
Oil spills pose a serious danger to marine ecosystems both offshore and on land. Various methods exist for removing oil from the water, and this article will cover the basics of four of them: physical, chemical, thermal, and biological. Physical remediation, which does not harm marine life much, is one of the eco-friendliest ways to clean up oil spills. The approach relies heavily on the ocean and its environs at the oil spill site, though. In marine ecosystems, the most cost-effective and efficient way to mitigate the effects of oil spills is to use booms, skimmers, and natural sorbents. Thermal treatment can remove up to 98% of oil spills with very little specialized equipment. This method works well when there is no wind, no recent spills, and no very combustible items. The risk of air pollution and harm to marine life is real, though. Even though it is dangerous to the environment, chemical remediation is a quick and effective way to clear up an event. Dispersing, breaking emulsions, sinking, washing surfaces, solidifying, and inhibiting are some of the many chemical properties used. The most effective methods for dealing with oil spills at sea include bioremediation, dispersion application, and mechanical oil recovery. Plans for responding to an oil spill could yield different outcomes depending on factors such as the type of oil, the microbes in the area, and water properties (such as temperature and nutrient availability). Government policies have a significant impact on catastrophe management and repair operations. Existing cleanup technology, such as skimmers and booms, has its share of issues, and biological approaches are particularly susceptible to the worldwide variability in climate, water currents, and wind. Cleanup techniques that pollute land and water and injure marine life, such as in situ procedures and dispersants, have high environmental costs.
Impact of Ultraviolet Radiation on the Growth Dynamics of Toxic and Nontoxic Microcystis aeruginosa.
Folorunsho OG, Fernandes Q, Wilson AB … +1 more , Ezekiel AO
Water Environ Res · 2026 Apr · PMID 41988826 · Publisher ↗
BACKGROUND: Harmful algal blooms (HABs) pose a significant threat to aquatic ecosystems worldwide, with freshwater environments being particularly vulnerable. Among the primary contributors to these blooms is Microcystis...
BACKGROUND: Harmful algal blooms (HABs) pose a significant threat to aquatic ecosystems worldwide, with freshwater environments being particularly vulnerable. Among the primary contributors to these blooms is Microcystis aeruginosa, a cyanobacterium known for producing toxins that are harmful to both human health and aquatic life. Given its toxic nature and ecological impact, understanding the factors that influence its growth is crucial. Since M. aeruginosa naturally inhabits sunlit surface waters, it is especially vulnerable to ultraviolet (UV) radiation stress, making this an ecologically and practically relevant area of study. Investigating the effects of UV radiation on M. aeruginosa growth can provide valuable insights into bloom dynamics, ecological consequences, and potential strategies for bloom management and control. OBJECTIVES: This study aims to examine the effects of UV radiation on the growth dynamics of both toxic and nontoxic strains of M. aeruginosa, specifically PCC 7806 and PCC 7005. METHODS: M. aeruginosa cultures PCC 7806 and PCC 7005 were exposed to varying levels of UV radiation (80, 60, and 20 mW/cm). Key parameters such as growth rates, cell concentrations, and the relative UV effects were monitored. Cell counts were determined microscopically and subsequently used to calculate the growth rate. RESULTS: UV radiation was found to exert a significant influence on the proliferation of both strains of M. aeruginosa, inducing discernible alterations in growth patterns and physiological mechanisms as compared to the control group. A one-way analysis of variance (ANOVA) indicated a significant effect of treatment intensity, with an F statistic of 13.71, p < 0.0001, and an R value of 0.5950. Pairwise comparisons revealed that the mean difference for the 80 mW/cm treatment was -4.458 (95% CI: -8.937 to -0.02000, p = 0.0514). Overall, the findings indicate that UV treatment intensity significantly influences growth, with the most pronounced effects observed at 80 mW/cm. CONCLUSIONS: Our data suggest that the growth of both M. aeruginosa strains, PCC 7806 and PCC 7005, is reduced under high UV radiation during algal blooms. A reduction in dense Microcystis blooms as a result of increased UV exposure could enhance light penetration in water bodies. These findings provide valuable insights for water resource management teams, enabling them to develop strategies to mitigate the public health risks associated with HABs.
Eco-Friendly Synthesis of CdO Photocatalyst: Tuning Structural, Morphological, and Optical Characteristics via Calcination Temperature.
Miraeez SA, Mohammed RY
Water Environ Res · 2026 Apr · PMID 41988687 · Publisher ↗
The resistance of azo dyes to degradation in wastewater, together with the limitations of conventional treatment technologies and the limited availability of green-synthesized cadmium oxide nanoparticles (CdO NPs) with t...
The resistance of azo dyes to degradation in wastewater, together with the limitations of conventional treatment technologies and the limited availability of green-synthesized cadmium oxide nanoparticles (CdO NPs) with tunable properties, represents a major environmental concern. To address these issues, CdO NPs were synthesized at various calcination temperatures (300°C-500°C) through a simple and cost-effective method using Ficus carica leaf extract as a reducing, capping, and stabilizing agent. Structural analyses revealed a calcination-induced phase transition from cadmium hydroxide (Cd(OH)) to crystalline CdO accompanied by a reduction in surface -OH groups, which can influence the surface properties and photocatalytic activity of the nanoparticles. The photocatalytic activity of CdO NPs, assessed via methyl orange degradation. The sample calcined at 500°C exhibited the highest efficiency, achieving 41% degradation in the absence of HO, which markedly increased to 95% upon HO addition. Furthermore, the reusability test over 5 cycles showed only a minimal decrease in photocatalytic activity, demonstrating the stability of the CdO NPs.
Comparative Performance of Bio-Derived Nanomaterials for Chromium Removal From Contaminated Water.
Mahdy AM, Fathi NO
Water Environ Res · 2026 Apr · PMID 41987459 · Publisher ↗
This study evaluated the efficiency of biosynthesized nanoparticles (NPs) derived from moringa seed waste (MSW-NPs), pomegranate peel (PP-NPs), sawdust (SD-NPs), and their combinations for the removal of hexavalent chrom...
This study evaluated the efficiency of biosynthesized nanoparticles (NPs) derived from moringa seed waste (MSW-NPs), pomegranate peel (PP-NPs), sawdust (SD-NPs), and their combinations for the removal of hexavalent chromium from contaminated water. The NPs were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX) analyses, revealing predominantly amorphous structures, highly porous morphologies, nanoscale particle sizes, and abundant surface functional groups favorable for adsorption. Batch adsorption experiments demonstrated that Cr sorption followed the Langmuir model, with MSW-NPs exhibiting the highest maximum adsorption capacity (q = 88.22 mg/g). Fourier-transform infrared spectroscopy (FTIR) analyses confirmed biomass-specific binding mechanisms, where MSW-NPs interacted mainly through amino and carboxyl groups, while PP- and SD-based NPs relied on oxygen-containing functional groups for surface complexation. Column experiments further verified the strong performance of these materials under continuous-flow conditions, with removal efficiencies ranging from 96% to 100%. MSW-NPs achieved complete Cr removal with minimal effluent chromium concentration, while combinations of NPs (MSW/PP, MSW/SD, and PP/SD) provided enhanced structural stability and synergistic adsorption behavior. The findings highlight that these green-synthesized NPs are low-cost, environmentally sustainable, and highly effective nano-biosorbents for Cr remediation. Their strong adsorption performance and operational stability make them promising candidates for practical wastewater treatment applications and scalable environmental remediation technologies.
Efficient Arsenic Removal From Groundwater Using Porous Iron Oxide Material Prepared via Iron-Embedded Cation Exchange Resin Beads.
Nguyen TT, Nguyen Thi CT, Tran Thi TD … +6 more , Nguyen Thi T, Nguyen HV, Le TT, Phan PT, Nguyen Thi QA, Nguyen NH
Water Environ Res · 2026 Apr · PMID 41986293 · Publisher ↗
In this study, porous iron oxide material (hereinafter referred to as p-FexOy), synthesized on the hard template of Indion 220Na by ion exchange between the sodium and iron ions, was used as a new and potential material...
In this study, porous iron oxide material (hereinafter referred to as p-FexOy), synthesized on the hard template of Indion 220Na by ion exchange between the sodium and iron ions, was used as a new and potential material for total arsenic (As) removal in real groundwater samples. The physicochemical properties of the materials were determined by advanced methods such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and mapping, transmission electron microscopy, and Brunauer-Emmett-Teller analyses. Although the study focuses on total As removal to align with the Vietnam National Technical Regulation on groundwater quality, the removal mechanism is discussed in relation to As speciation and surface charge. Selective As(V) removal occurs in acidic media, whereas both As(III) and As(V) are efficiently adsorbed near the point of zero charge (pH = 7.15). The maximum adsorption capacity (Q) reached 0.228 mg/g at a suitable pH range of 7-9 and an adsorption equilibrium time of 60 min. The equilibrium data were best described by the Langmuir isotherm model (R = 0.999), indicating monolayer adsorption on a homogeneous surface, while the adsorption kinetics followed the pseudo-second-order model (R = 0.9946). These findings suggest that p-FexOy would have many potential applications in environmental remediation.
Modeling Method for AO Anoxic Zone Based on PSO-SCN.
Lu W, Tian X, Guan Y … +2 more , Ma Y, Zhao J
Water Environ Res · 2026 Apr · PMID 41986152 · Publisher ↗
This study proposes a particle swarm optimization-optimized stochastic configuration network (PSO-SCN) model for the anoxic zone of the AO wastewater treatment process by integrating mechanistic analysis with data-driven...
This study proposes a particle swarm optimization-optimized stochastic configuration network (PSO-SCN) model for the anoxic zone of the AO wastewater treatment process by integrating mechanistic analysis with data-driven modeling. Data processing involves the use of isolation forest for outlier handling, KNN for missing values, and KPCA for dimensionality reduction (from seven to four dimensions). Validated with data from an AO simulator and an actual wastewater treatment plant, the model demonstrates superior accuracy (RMSE and NSE) in predicting effluent COD, NH -N, and NO -N concentrations compared to the unoptimized SCN model, the traditional mechanistic model (ASM1), and other classical models such as PSO-BP and PSO-RBF. Furthermore, SHAP analysis enhances the model's interpretability. The results indicate that the PSO-SCN framework achieves an effective balance among prediction accuracy, computational efficiency, and mechanistic interpretability, providing a valuable basic tool for intelligent wastewater treatment control.
Synergetic Oxidation and Adsorption of Arsenite by Core-Shell β-FeOOH@MnO Nanocomposite for Enhanced Removal of Arsenic From Water.
Li S, Zhou Y, Wang S … +2 more , Yao S, Xiao M
Water Environ Res · 2026 Apr · PMID 41986087 · Publisher ↗
Arsenic contamination in water, particularly from highly toxic arsenite (As(III)), continues to pose a significant global public health challenge due to its high mobility and resistance to conventional treatment methods....
Arsenic contamination in water, particularly from highly toxic arsenite (As(III)), continues to pose a significant global public health challenge due to its high mobility and resistance to conventional treatment methods. This study presents an innovative core-shell β-FeOOH@MnO nanocomposite, which synergistically integrates MnO nanosheets to oxidize As(III) into adsorptive arsenate (As(V)) and β-FeOOH to facilitate the efficient uptake of As(V). This approach addresses common limitations such as particle aggregation and suboptimal adsorption observed in pure MnO systems. The nanocomposite, synthesized by hydrothermal methods, exhibits a doubled surface area of 172.95 m/g, offering numerous active sites and mesopores conducive to rapid mass transfer. Under optimized conditions (pH 3.0, 0.4-g/L dosage), the nanocomposite achieved 98.39% removal of As(III) and a maximum adsorption capacity of 50.26 mg/g at 25°C, following pseudo-second-order kinetics and endothermic chemisorption. Characterization techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), confirmed the synergistic mechanism, wherein MnO oxidizes As(III) through the reduction of Mn to Mn, and the resulting As(V) is adsorbed by β-FeOOH. This advancement offers a cost-effective and efficient solution for improved arsenic remediation in water treatment applications.
Plant-Derived Bio-Carriers in MBBRs Enhancing Heterotrophic Nitrification-Aerobic Denitrification for Sustainable Aquaculture Wastewater Treatment.
Adeniyi I, Zhao YG, Mupindu P … +2 more , Yang X, Gao M
Water Environ Res · 2026 Apr · PMID 41983713 · Publisher ↗
Sustainable wastewater treatment in recirculating aquaculture systems (RAS) requires efficient nitrogen removal, yet conventional plastic-based biocarriers pose environmental concerns. This study evaluates Luffa cylindri...
Sustainable wastewater treatment in recirculating aquaculture systems (RAS) requires efficient nitrogen removal, yet conventional plastic-based biocarriers pose environmental concerns. This study evaluates Luffa cylindrica-based bio-carriers, particularly modified luffa sponge (MLS), as an eco-friendly alternative for enhancing nitrogen removal in HNAD-MBBRs while simultaneously examining system performance under sequential C/N variation representative of RAS wastewater conditions. Three laboratory-scale HNAD-MBBRs were compared, each using a distinct bio-carrier: MLS, unmodified luffa sponge (ULS), and plastic K3 Kaldnes carriers (PKC). The systems operated for 56 days under varying carbon-to-nitrogen (C/N) ratios (10.5, 7, and 5). Microbial community analysis (16S rRNA sequencing) and biofilm morphology (SEM imaging) were conducted. The MLS outperformed other carriers, achieving 99.93% ammonium, 99.49% nitrite, and 99.19% nitrate removal at a C/N ratio of 7. Microbial analysis revealed a richer population of nitrogen-cycling bacteria such as Thauera and Hydrogenophaga on MLS, while SEM confirmed dense biofilm colonization with rod-shaped bacteria and extracellular polymeric substances (EPS). The MLS-based wastewater treatment system demonstrates superior nitrogen removal efficiency and microbial support, offering a sustainable alternative to plastic biocarriers in MBBRs. This aligns with global efforts to reduce plastic waste in aquaculture while maintaining high treatment performance.
Comparative Assessment of Artificial Intelligence Models for Predicting Water Quality in a Reverse Osmosis Desalination Plant.
Mezhoud C, Sahnoune R, Bouchraki F … +1 more , Berreksi A
Water Environ Res · 2026 Apr · PMID 41958195 · Publisher ↗
The increasing scarcity of freshwater resources underscores the strategic importance of seawater desalination. However, optimizing reverse osmosis (RO) systems remains challenging because of raw water variability, high e...
The increasing scarcity of freshwater resources underscores the strategic importance of seawater desalination. However, optimizing reverse osmosis (RO) systems remains challenging because of raw water variability, high energy consumption, and membrane degradation. This study investigates the use of artificial intelligence (AI) for predictive monitoring of the Cap Djinet desalination plant (Boumerdès, Algeria), based on real operational data. Six supervised learning algorithms, linear regression (LR), polynomial regression (PR), support vector regression (SVR), random forest (RF), extreme gradient boosting (XGBoost), and multilayer perceptron (MLP), were evaluated for predicting the physicochemical and chemical parameters of the produced water. The findings indicate that ensemble models, particularly XGBoost (R = 0.999; RMSE = 6.11; MAPE = 2.23%), outperform other methods, followed by RF and SVR. Although simple, the LR model demonstrated strong robustness (R = 0.999; RMSE = 4.90), making it suitable for daily operation. The analysis further indicates that the performance of complex models, such as the MLP, is strongly influenced by the limited sample size (MAPE = 65.45%), illustrating the sensitivity of deep learning approaches in small-data contexts. While this frames the applicability of the results within the scope of the available dataset, it remains representative of the operational conditions commonly encountered in desalination plants with restricted yet meaningful datasets. Overall, XGBoost, RF, SVR, and LR demonstrate significant potential for predictive monitoring and sustainable optimization of desalination processes.
Efficiency and Selectivity Study of Eco-Extracted Chitosan for Potentially Toxic Elements Removal From Brassware Effluents.
ElKnidri H, Belaabed R, Addaou A … +1 more , Laajeb A
Water Environ Res · 2026 Apr · PMID 41952529 · Publisher ↗
This study investigated the efficiency of eco-extracted chitosan obtained through a microwave-assisted method for removing potentially toxic elements from synthetic solutions and industrial effluents. The obtained result...
This study investigated the efficiency of eco-extracted chitosan obtained through a microwave-assisted method for removing potentially toxic elements from synthetic solutions and industrial effluents. The obtained results disclosed that the removal efficiency of metal ions depends on several parameters, including contact time, adsorbent dose, deacetylation degree of chitosan, initial metal ion concentration, and solution pH. Kinetic analysis showed that the adsorption process follows a pseudo-second-order model, suggesting that the chemisorption mechanism dominates the adsorption process. Additionally, equilibrium data fitted well with the Langmuir isotherm, indicating monolayer adsorption with a homogeneous adsorbent surface and limited binding sites. Maximum adsorption capacities were 31.78 mg/g for Ag, 30.57 mg/g for Cu, 14.49 mg/g for Ni, and 37.21 mg/g for Pb. Thermodynamic analysis revealed that the adsorption of Ag, Cu, and Pb occurs spontaneously across all temperatures, whereas the adsorption of Ni is non-spontaneous, implying that Ni removal is less favorable. Regarding desorption, although studies show a slight decrease in efficiency over successive cycles, chitosan remains a highly reusable material, especially for metals like Ag and Pb. To assess the treatment performance on real brassware effluent, two types of wastewater were analyzed: a single-metal effluent containing only Ni, and a multi-metal effluent comprising Ag, Cu, and Ni. The adsorption capacity for Ni increased to approximately 56 mg/g, demonstrating the high chitosan efficiency in treating complex effluents brassware. In the multi-metal system, monovalent ion Ag was preferentially adsorbed over divalent ions, indicating selective adsorption behavior. The results obtained highlight the potential of eco-extracted chitosan as a sustainable and eco-friendly adsorbent for the removal of potentially toxic elements from industrial effluents.
Enhanced Microplastic Flotation: Unraveling the Role of Bubble-Chain Hydrodynamics via PIV Analysis.
Nam HJ, Han SJ, Kim JJ
Water Environ Res · 2026 Apr · PMID 41952365 · Full text
Understanding the transport behavior of microplastic particles in flotation systems is critical for enhancing their removal efficiency in wastewater treatment processes. Here, we investigated the particle-lifting effect...
Understanding the transport behavior of microplastic particles in flotation systems is critical for enhancing their removal efficiency in wastewater treatment processes. Here, we investigated the particle-lifting effect of a bubble-chain system on polystyrene (PS) particles under continuous rising flow conditions. A custom-built chamber equipped with syringe-driven needle injectors generated successive air bubbles with mean equivalent diameters of 3.21 and 2.81 mm. As the number of bubbles (N) increased from 1 to 10, the nondimensionalized vertical displacement (L) of PS particles increased from 5.29 to 7.66 and 4.53 to 6.07 for 3.21 and 2.81-mm bubbles, respectively. Correspondingly, the nondimensionalized total displacement (L) increased from 5.58 to 8.31 and 4.78 to 6.52, showing maximum increases of 44.8% and 48.7%, respectively. As the number of bubbles increased, the axial motion of the particles was significantly enhanced, which was attributed to the vertical expansion of the flow field, the increase in vorticity, and the formation of asymmetric flow structures as identified through particle image velocimetry (PIV) analysis. The formation of overlapping vortices within bubble-chain systems substantially broadens the effective hydrodynamic field, facilitating improved flotation of microplastic particles. This extended flow structure provides a quantifiable framework for enhancing the efficiency of dissolved air flotation (DAF) technologies, particularly in applications targeting microplastic separation.
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