Water Environment Research最新文献

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%.

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.

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.

This study assessed variations in water quality at the Indus River Basin (IRB) impacted by wastewater (WW) drains from five densely populated urban and industrial cities: Lahore, Faisalabad, Multan, Sukkur, and Hyderabad. Water samples from the barrages at upper and lower IRB, tributaries, and cities' WW drains were analyzed. GIS-based mapping was used to visualize the transport of pollution from the WW drains to the riverine bodies, identifying potential source cities and pathways of pollution. Employing sensitivity analysis through various models and validation matrices enhances the statistical reliability of hotspot mapping water quality variations. The riverine samples from the upper basin exhibited relatively good water quality with low COD and TOC levels. However, the COD levels at the Balloki and Panjnad barrages downstream of the Ravi and Chenab exceeded 160 mg/L. The analyzed WW drains in Lahore and Faisalabad discharged into the Ravi River and recorded high COD and TDS levels up to 600 and 4000 mg/L, respectively. Drains from the downstream Hyderabad region worsened contamination, with COD reaching 198 mg/L. Seasonal assessments revealed elevated pollutant concentrations during the dry season, with COD and TDS levels increasing by 1.68 and 1.58 times, respectively, compared to the wet season.

The textile industry significantly contributes to water pollution due to extensive dye usage, particularly reactive dyes, which are highly soluble, chemically complex, and poorly biodegradable. Advanced oxidation processes (AOPs) have emerged as effective alternatives for their removal. This review summarizes reactive dye properties and critically examines AOP applications in both synthetic and real textile effluents. Evaluated configurations include ozonation, Fenton's reagents, UV-based systems, electrochemical processes, and cavitation, which generate hydroxyl radicals (OH^•) and, in newer approaches, sulfate (SO₄ ^•-) and chlorine (Cl^•) radicals. In synthetic effluents, AOPs achieve over 90% removal of color, chemical oxygen demand (COD), and total organic carbon (TOC), whereas real effluent performance decreases because of matrix complexity; combined systems often exceed 80% efficiency. Stepwise evaluation from model solutions to actual wastewater aids in understanding reaction mechanisms and optimizing conditions. With appropriate optimization and integration into conventional treatments, AOPs show strong potential as industrially viable technologies for advanced textile wastewater remediation.

Bio-clogging is critical to the efficiency of soil aquifer treatment. In this study, we utilized a percolation column device to investigate the dynamic evolution of biofilm and the corresponding responses changes of three typical hydraulic properties with the column within the percolation column. The results showed that the biofilm development exhibited five-stage growth morphology: bacterial stage, colony stage, biofilm with filamentous EPS stage, biofilm with mesh EPS stage, and dense biofilm stage. The hydraulic conductivity exhibited nonuniform decay across five stages: initial fluctuation period, swiftly declining period, accelerated declining period, gently decreasing period, and equilibrium stabilizing period. Both bacteria and EPS contribute to the attenuation of the infiltration properties. Due to its hydrophilic nature, EPS played a more prominent role in storing and dispersing water. As such, significant changes in water holding capacity and material transport mechanism occurred at EPS secretion onset. From 0-18 h, bacterial colonization slightly enhanced water retention, accompanied by a gradual rise in the hydraulic dispersion coefficient. After approximately 18 h, substantial EPS production markedly increased water-holding capacity and transformed the dominant transport mechanism from convection to dispersion.

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 m², 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.

Nitrate in drinking water is a known health hazard for infants, although a growing body of epidemiological evidence suggests an increased risk of adverse pregnancy outcomes and some cancers. A major constraint of epidemiological research is the ability to quantify nitrate concentrations in public drinking water supplies over time. Data on nitrate concentrations in public drinking water supplies were retrieved by information requests, linked to a national dataset on the spatial extent of water distribution zones (WDZs) and linked with census information. We applied a number of data cleaning and imputation processes to address complexities in the raw data as well as missingness. In total, 599 WDZs (95.4%) had at least one nitrate measurement between 2000 and 2024 (n = 20,875 raw observations). After applying a set of imputation methods, the final dataset covered 89.8% of all person-years (n = 92,800,000) of the population on a public drinking water supply during the most recent period from 2000 to 2024. Overall, XGBoost imputation outperformed a range of other imputation methods when synthetic missingness was added to the original data. The large majority (95.3%) of the population was estimated to be on drinking water supplies of less than 1 mg/L nitrate-nitrogen. The population-weighted median nitrate concentration was 0.05 mg/L (IQR 0.04-0.36). This extensive assessment provides the foundation for epidemiological research into the health effects of nitrate contamination of drinking water in New Zealand. The effectiveness of the system for drinking water nitrate surveillance could be enhanced in several ways that would improve its ability to meet its intended purpose.

Water resource recovery facilities often receive landfill leachate (LL), which can disrupt biological processes due to its toxicity and low biodegradability. This study evaluates the anaerobic codigestion (AcoD) of municipal wastewater (MWW), LL, and crude glycerin (CG) as a strategy to enhance organic matter removal and methane yield. Batch reactors were operated under varying conditions defined by a Plackett-Burman screening design, and methane production kinetics were modeled using modified Gompertz and Cone equations. Soluble chemical oxygen demand (sCOD) removal ranged from 67.4% to 94.3%, whereas methane yield varied between 0.076 and 0.349 L _NCH4/g tCOD_add (liters of normalized methane per gram of total COD added). The highest yield was achieved with 2% LL and 1% CG, approaching the theoretical maximum. Statistical analysis revealed that increasing CG content reduced methane yield, and extending the digestion time to 40 days offered limited performance gains. Despite the presence of inhibitory compounds, most conditions showed stable digestion, with short latency phases and effective microbial adaptation. These findings demonstrate the feasibility of codigesting MWW, LL, and CG, especially under optimized proportions, and highlight the potential for energy recovery in wastewater treatment plants using biodiesel by-products.

This work highlights the phenomena that may occur on zinc electrodes used as sacrificial electrodes in a process for treating an effluent containing urea. Zinc ions (Zn²⁺) generated in situ promote coagulation, but in some cases, electrode passivation and localized corrosion can hinder dissolution and reduce treatment efficiency. For this reason, the effect of operational parameters such as current density, initial urea concentration, pH, and supporting electrolyte (NaCl) concentration on urea removal was studied in the first part. While the second part was dedicated to investigating the impact of urea and NaCl electrolyte concentrations on the electrochemical behavior of the zinc electrode, this was done by using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and cyclic voltammetry, while surface changes were analyzed via scanning electron microscopy coupled with energy-dispersive spectroscopy and x-ray diffraction. The obtained results show that the highest urea removal was obtained with the operating conditions: current density of 22 mA/cm², pH 10, 25 mmol/L NaCl, and an initial urea concentration of 20 mmol/L: 12 mmol/L of urea was removed, corresponding to 91 mg/L of dissolved zinc, a faradaic efficiency of 110%. With regard to the surface state of zinc, it was demonstrated that passivation through zinc oxide formation was confirmed by PDP analysis. The results revealed the presence of ZnO crystalline phases as well as surface deposits, both indicative of the development of an oxide layer, which limited further zinc dissolution and floc generation under specific EC operating conditions. Zinc corrosion behavior was strongly influenced by pH, chloride concentration, and urea levels, as evidenced by electrochemical diagnostics (polarization curves and impedance spectra). At alkaline pH and moderate chloride concentrations, enhanced zinc release was observed, while higher urea levels promoted surface degradation and oxide accumulation. These findings highlight the need to balance dissolution and passivation of electrodes to optimize EC performance for nitrogenous pollutant treatment.