Water Environment Research最新文献

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_m) of AS treatment by 44%, 67%, and 45%, respectively. The variation in the maximum degradation potential (D_max) 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_m or D_max 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.

Pharmaceuticals and personal care products (PPCPs) contamination in aquatic environments has attracted considerable research attention, yet most studies focus on treatment technologies while the governance mechanisms coordinating stakeholder behavior remain underexplored. This study develops a tripartite evolutionary game model to analyze strategic interactions among pharmaceutical enterprises, wastewater treatment plants, and government environmental agencies in PPCPs pollution control. Replicator dynamics and stability analysis identify six stable equilibrium configurations and reveal that complete cooperation equilibrium cannot achieve asymptotic stability due to government fiscal incentives for regulatory withdrawal. Results demonstrate that technology-upgrading decisions of treatment plants respond primarily to government subsidies and penalties rather than upstream enterprise behavior. The mathematical finding that upstream enterprise production choices do not directly alter treatment plant upgrading incentives through cost transmission channels reveals that market-based coordination cannot spontaneously emerge without regulatory intervention, thereby strengthening the theoretical case for sustained government engagement. Sensitivity analysis indicates that reducing clean production costs and enhancing green product revenues accelerate system convergence toward environmentally favorable equilibria. Additional sensitivity analysis of treatment plant subsidy and penalty parameters confirms that both positive incentives and negative sanctions effectively promote technology adoption when appropriately calibrated. These findings provide theoretical guidance for designing differentiated policy instruments that balance market incentives with sustained regulatory oversight.

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 (CH₄) and 17%-22% to sludge, yielding 205-255 L CH₄ 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 NH₄ ⁺-N at an OLR of 0.84-5.43 kg COD/(m³·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.

Bisphenol A (BPA), a pervasive endocrine-disrupting compound (EDC), threatens microbial nitrogen cycling, yet its mechanisms in disrupting aerobic denitrification remain poorly defined. This study elucidates the inhibitory effects of BPA on Pseudomonas stutzeri HD4-1. Dose-dependent suppression was evident: nitrate reduction rates decreased by 33%-95% at ≥ 1 mg L^-1 BPA, accompanied by nitrite accumulation (54.7-78.3 mg L^-1) and exponential N₂O emission (76.7 mg L^-1, 147-fold increase). Mechanistically, BPA induced oxidative stress (ROS: 152.6%-225.6% of control), cytomembrane damage (LDH release: 125.6%-232.1%), and metalloenzyme inactivation (N₂OR activity inhibition: 94.5%-96.4%). Concurrent transcriptional repression-notably of nosZ (2.8-9.3-fold suppression)-impaired N₂O reduction, compounded by 33%-77% declines in electron transport system activity (ETSA), exacerbating metabolic bottlenecks. Gene inhibition hierarchy (nosZ > cnorB > nirS > napA) mirrored preferential failure of terminal denitrification steps. The insight into effect mechanism of BPA on aerobic denitrification is of particular significance to provide its ecological risk assessment in aquatic ecosystems and upgrade nitrogen removal process in EDC-containing wastewater treatment plant.

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.

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 (C₁₄H₆O₈) 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 [C₁₄H₈O₁₀Fe]^- 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.

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.

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.

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.

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.