Water Environment Research最新文献

The increasing number of artificial dyes from industrial processes contaminating water sources requires more efficient and sustainable techniques for wastewater remediation. This study involves the utilization of litchi (Litchi chinensis) fruit peels in the green synthesis of magnesium oxide nanoparticles (MgO-NPs). Further, for the characterization of eco-friendly MgO-NPs, ultraviolet-visible spectra, Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering, scanning electron microscopy (SEM), and X-ray diffraction (XRD) spectroscopy were utilized. An absorption peak at 274 nm from UV-visible spectroscopy indicates the development of MgO-NPs. The particle average size was found to be 96.33 nm with a polydispersity index of 0.32. The application of the synthesized nanoparticle was evaluated for the removal of malachite green and Eriochrome Black T. The biosynthesized nanoparticles demonstrated an enhanced photocatalytic activity, effectively removing malachite green (95.66%) and Eriochrome Black T (92.69%) from contaminated water under solar light irradiation. These results reveal that the green-synthesized MgO-NPs achieved significant efficiency in dye removal, highlighting their potential as a cost-effective and sustainable approach for wastewater treatment applications.

This study aimed to evaluate the hydrodynamic behavior of a vertical subsurface flow constructed wetland (VSSF-CW) treating domestic sewage by applying a saline tracer, comparing system performance in operational Years 3 (NR-3) and 5 (NR-5), and assessing the influence of a rainfall event (R-5). Electrical conductivity monitoring was used to construct residence time distribution (RTD) curves for all tests, enabling detailed characterization of hydraulic behavior. As a result, the system exhibited highly dispersed flow (d > 1.21; N < 2.07) with a tendency toward continuous stirred tank reactor (CSTR) behavior. A comparison between NR-3 and NR-5 tests revealed significant differences (p < 0.05, t test) in the hydrodynamic parameters. The rainfall event (R-5) had a statistically significant effect (p < 0.05, t test), decreasing hydraulic retention time, increasing dilution, and enhancing dispersive flow within the treatment unit. These findings highlight the importance of long-term hydrodynamic monitoring in VSSF-CW systems and demonstrate how operational conditions and external factors such as rainfall can influence treatment performance.

The limitation of membrane filtration is that it only filters out pollutants but does not treat them thoroughly; therefore, catalytic membranes are a synergistic combination of membrane filtration and catalytic decomposition of pollutants. This study focuses on synthesizing mixed oxides Cu-Mn-O with different ratios and coating the optimal onto a PET membrane using a dip-coating method. The materials were thoroughly characterized through FTIR, XRD, TGA, zeta potential, EDS, BET, and SEM. The 3:1CuO/MnO₂ showed a low-order structure and seems to be amorphous through XRD results. SEM results showed that the mixed oxide nanoparticles have a porous structure, ultra-small size, and uniform distribution. The large specific surface area of the 3:1CuO/MnO₂ (64.09 m²/g) enhances the surface-active sites. In adsorption and degradation tests, the 3:1CuO/MnO₂ consistently showed the highest efficiency for both Congo red (CR) and methylene blue (MB). Specifically, the CR degradation reaction followed pseudo-second-order kinetics (PSO), while the MB degradation process conformed to pseudo-first-order kinetics (PFO). In membrane filtration, the water flux reached 170.5 L/m².h for the PET membrane and decreased to 124.7 L/m².h for the 3:1CuO/MnO₂/PET membrane due to the filling of the catalytic particles. Notably, the CR rejection of the 3:1CuO/MnO₂/PET membrane surged from 74.3% to 96.7% in the presence of peroxydisulfate (PDS). ROS (reactive oxygen species) trapping tests identified singlet oxygen as the primary oxidizing agent. Finally, the catalytic membrane exhibited impressive durability with stable performance after 4 cycles, opening up potential practical applications in textile wastewater treatment.

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 (NH₄ ⁺-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%.

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_TEM, bla_SHV, and blao_XA) 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_TEM, bla_SHV, and bla_OXA), 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.

The definitive screening design (DSD) represents a novel and highly efficient methodological approach that enables researchers to gain critical insights with minima experimental runs, significantly enhancing process efficiency and accelerating research outcomes. In this study, DSD was employed to examine the effects of nine process variables on the degradation of a textile dye using an electro-Fenton (EF) system with reticulated vitreous carbon (RVC) cathodes and boron-doped diamond (BDD) anodes. The primary goal was to assess the predictive capability of DSD in characterizing the complex EF system coupled with BDD electrodes and to optimize industrial dye treatment in wastewater, using a reduced experimental set. Only 23 experiments were needed to screen the effects of dye concentration, current density, NaCl and Na₂SO₄ concentrations, pH, temperature, interelectrode distance, stirring rate, and Fe²⁺ concentration. Subsequently, an optimal augmented design (OAD) was applied, adding eight more runs to refine the process characterization. Statistical analysis identified temperature, current density, and dye concentration as the key factors influencing total organic carbon (TOC) removal, with significant interactions observed between temperature and current density, and between pH and dye concentration. Under optimal conditions, a 73.1% reduction in TOC was achieved after 90 min. This study highlights the novel combination of DSD and OAD as a powerful approach for identifying critical process parameters and optimizing the treatment of industrial dyes in wastewater with reduced experimental effort and enhanced accuracy.

Anaerobic digestate, a typical by-product of large-scale biogas plants, faces mounting disposal pressure due to the rapid increase in organic solid waste. In this study, an iron-carbon composite was produced from digestate through polyethylene glycol (PEG)-assisted iron modification followed by low-temperature carbonization. The resulting material exhibited a mesoporous texture, oxygen-containing surface functionalities, and Fe₃O₄/Fe₃C domains, enabling efficient removal of Congo red in batch systems. Removal was favored under mildly acidic conditions. At pH 4 and 298 K, the maximum experimentally observed equilibrium uptake reached 1267.35 mg·g^-1 at high initial concentration, and removal efficiencies approached 99% under the tested conditions. The adsorbent retained more than 95% of its initial removal performance after five regeneration cycles. Kinetic and equilibrium analyses, together with FTIR/XPS and post-adsorption characterization, support that uptake involves Fe-associated interactions, electrostatic effects, and hydrogen bonding, with additional high-coverage accumulation contributing at elevated concentrations. Overall, this work demonstrates a practical route to valorize anaerobic digestate into a reusable adsorbent for removing azo dyes from wastewater.

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 m³), sand (0.005 m³), and PHBC 350 (0.0075 m³) 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.

This study provides an automated classification tool for assessing the quality of drinking water distributed through supply networks. The methodology is based on the construction of a global quality index, using the multicriteria analytic hierarchy process method, which enables the objective weighting of 23 parameters: physico-chemical and bacteriological. The classification process, divided into five quality classes, is fully automated through a python algorithm, ensuring an evaluation that is both rapid and precise. Application to an extensive database of 1718 samples from the water service of the city of Bejaia (Algeria) revealed that 97.56% of cases fall within the good and very good quality classes, thereby confirming the effectiveness of the public distribution service. Sensitivity analysis using the Sobol method highlighted the decisive importance of certain parameters: specifically, total coliforms, manganese, calcium, and conductivity in defining the final quality. Flexible and operational, the tool allows managers to quickly identify at-risk situations and to target corrective interventions at critical indicators. Thus, this model constitutes an innovative and effective approach to strengthening monitoring and ensuring intelligent management of drinking water quality.

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.