The use of titanium oxide (TiO₂) in electrochemical systems has been intensively investigated for developing conductive and active electrodes. However, achieving an effective reaction using geometric and electronic structures remains a challenge. Herein, we report the in situ synthesis of TiO₂ mesocrystals within a flow-through titanium (Ti) plate using an electrochemical method. We developed an electrochemical reactive membrane (REM) for the rapid removal of organic pollutants from water. At a low current density (3 mA/cm²), the removal rate of p-nitrophenol through the TiO₂ mesocrystal–based REM was 95% within 20 min. The REM demonstrated a service lifetime of > 1900 h and an energy consumption of 30 kWh (kg⁻¹ chemical oxygen demand) for treating organic pollutants in water. The abundant nanochannels of TiO₂ mesocrystals can effectively regulate the hydroxy radical reaction pathway, promoting its interaction with organic compounds more compared with the anode. This greatly enhances the electrochemical oxidation of organic pollutants in aqueous solution.

Achieving satisfactory micropollutant oxidation with a low hydrogen peroxide (H₂O₂) concentration is vital for advanced oxidation processes to improve catalytic efficiency and reduce resource consumption. Herein, the efficient conversion of low-concentration H₂O₂ (20 μmol/L) triggered by dissolved oxygen (DO) over carbon-supported nanoscale zero-valent iron prepared in this study (nZVI–C) for efficient contaminant degradation is achieved. The experimental results revealed that 1) H₂O₂-DO systems promoted electron transfer between nZVI–C and iron species, followed by the generation of more abundant reactive oxygen species, which was quite different from the alone H₂O₂ or DO systems mostly their-self function for limited reactive oxygen species generation; 2) The in-situ generation of H₂O₂ via DO activation played a significant role. The H₂O₂–DO system effectively degraded ofloxacin (OFL), norfloxacin (NOR), and ciprofloxacin (CIP) degradation at low concentrations (5 μmol/L). With the addition of 10 mg/L nZVI–C and 20 μmol/L H₂O₂, the degradation rates of OFL, NOR, and CIP reached 93.25%, 90.71%, and 92.80%, respectively, within 15 min. DO activation and catalyst adsorption contributed 44.93%, 39.84%, and 36.19%, respectively. Theoretical calculation results further demonstrated the stretching of O–O bonds in O₂ and H₂O₂ molecules, indicating a possible homolytic reaction. This study elucidates the triggering role of low-concentration H₂O₂ in DO conversion over nZVI, providing an efficient strategy for the Fenton degradation of micropollutants with a low dosage of catalysts and oxidants.

Contact-electro-catalysis (CEC) is an emerging catalytic approach that converts mechanical energy into chemical redox activity through contact-electrification-induced interfacial electron transfer. By enabling redox reactions at dynamically contacting interfaces without continuous electrical bias or light irradiation, CEC expands the catalyst landscape beyond conventional semiconductors and metals to include dielectric polymers and insulating oxides. This unique feature has stimulated growing interest in its applications for pollutant degradation, hydrogen peroxide production, methane oxidation, carbon dioxide reduction, and metal recovery. This review provides a systematic assessment from an integrated mechanism–material–engineering perspective. At its core, it constructs a unified mechanistic framework that establishes intrinsic logical connections across diverse applications based on common electron-transfer pathways. Furthermore, we systematically evaluate various material modification strategies designed to enhance CEC performance. Our analysis reveals that despite the broad applicability of CEC, the core bottleneck impeding its translation to practical implementation is the lack of standardized, quantitative performance reporting protocols. Current literature frequently omits critical quantitative metrics, including mechanical energy input, energy-normalized product yields, and long-term catalyst stability under realistic operating conditions. While surveying typical application scenarios, this review critically dissects current limitations in the field, such as insufficient mechanistic verification techniques, challenges in controlling product selectivity, and constraints in reactor scale-up. Accordingly, we propose a set of standardized data-reporting guidelines and outline key future research directions—specifically, operando characterization, theory-guided material discovery, and process engineering optimization—aiming to advance CEC from proof-of-concept laboratory studies toward practical engineering applications in environmental remediation and energy conversion.

Prophages, which are temperate bacteriophages integrated into bacterial chromosomes, serve as pervasive but understudied regulators of microbial ecology in aquatic environments. While they confer benefits such as enhanced virulence, stress resistance, and metabolic flexibility during lysogeny, environmental stressors can induce their lytic cycle, culminating in host cell lysis and phage dispersal. This review synthesizes current knowledge on prophage identification methodologies, environmental distribution patterns across diverse aquatic habitats (marine, freshwater, and wastewater systems), and their diverse roles in modulating environmental processes. Activation triggers and molecular pathways are systematically analyzed, alongside an assessment of their impacts on 1) biogeochemical cycling of C, N, P, and S; 2) dual regulation of biofilm dynamics; and 3) the dissemination and persistence of antibiotic resistance genes. The potential use of prophage derived endolysins as biocontrol agents is also discussed. By pinpointing key knowledge gaps—including in situ quantification of prophage induction, connecting prophage activity to community level processes, and validation under environmentally relevant conditions—this review proposes an integrated framework and priority research directions for aquatic prophage research, with cautious consideration of applications for water quality management and public-health protection.

Perfluoroalkyl substances (PFASs) are globally concerning pollutants due to their persistence, bioaccumulation potential, and adverse human health effects. As a densely populated and industrially intensive region suffering complex water pollution, the Haihe River Basin (HRB) in China is a priority area for PFAS research. This study clarified the occurrence characteristics and bioaccumulation patterns of PFASs in the middle and lower reaches of the HRB, derived ambient water quality criteria (AWQC) for seven PFASs, and assessed the potential non-carcinogenic human health risks. PFOA was the dominant compound in surface water (mean: 35.84 ng/L), while PFOS was most abundant in biota (1.16 ng/g). Chemical properties (45.3%) and PFASs concentration in water (26.8%) were the primary drivers of bioaccumulation factor (BAF) variation. BAFs displayed a non-monotonic pattern across carbon chain lengths (C8 < C6 < C4 < C9 < C10). AWQC were derived across different age groups and exposure scenarios. The AWQC values followed a consistent order of PFHxS < PFOS < PFNA < PFDA < PFHxA < PFOA < PFBA. Children aged 2–6 yr were identified as the most sensitive population. Human health risk assessment revealed Mentougou region in Beijing as a spatial hotspot. Drinking water was the dominant exposure pathway for PFOA, whereas fish consumption was the main route for other PFASs. Notably, PFOA, PFHxA, and PFHxS posed potential non-carcinogenic risks (HQ > 1) under certain specific scenarios. The results of this study could support the development of water quality criteria and risk-based management strategies for PFASs in industrialized watersheds.

Reliable preservation and reactivation of functional fungal-bacterial granules (FBGs) is a key barrier to fungal-based wastewater treatment, particularly in cold regions where biomass start-up and recovery are slow and unstable. Preservation has been studied for aerobic granular sludge (AGS) and fungal pellets, but a systematic framework for FBGs is lacking. Here, the short-term preservation and reactivation of FBGs after three days of storage was systematically evaluated by comparing deep freezing (−80 °C), moderate freezing (−15 °C), and room-temperature drying, followed by structural and functional reactivation under room-temperature and low-temperature (15 °C) wastewater treatment conditions. Freezing preserved granule integrity and biomass quality, whereas drying reduced the organic fraction and impaired settleability, particularly under low-temperature conditions. At room temperature, all preserved FBGs achieved high chemical oxygen demand (COD) removal (93%–97%) and effective NH₄⁺-N removal (74%–79%), with −15 °C preservation providing the most stable reactivation and settleability. Microsensor profiling indicated that −15 °C preservation supported deeper oxygen penetration at room temperature, whereas −80 °C FBGs maintained higher near-surface oxygen at 15 °C. At 15 °C, COD removal remained high (84%–87%), whereas NH₄⁺-N removal was moderate (35%–37%), suggesting limited ammonium-transformation capacity. One-way ANOVA indicated statistically insignificant differences (p > 0.05) among preservation strategies for COD, NH₄⁺-N, or NO₃⁻-N removal after acclimation. Preserved FBGs retained bacterial and fungal taxa associated with biofilm formation, stress tolerance, or granule stability, whereas control FBGs disintegrated under cold stress. Overall, FBGs withstood short-term preservation and were reactivated without compromising structural integrity or organic-matter removal under the conditions tested.

The metallurgical industry is an important anthropogenic source of atmospheric particulate matter and associated heavy metals. However, the size distribution, chemical profiles, and potential toxic burdens of particulate matter emitted from metallurgical sources remain insufficiently characterized. In this study, a dilution sampling system was used to collect particulate matter in four size fractions from nine typical metallurgical processes in China, covering zinc, copper, aluminum, tin, lead, and iron/steel smelting. A total of 51 chemical species, including inorganic elements, water-soluble ions, and carbonaceous components, were systematically characterized, and size-resolved emission factors were calculated. The results showed that pyrometallurgical and hydrometallurgical zinc smelting emitted the highest total particulate matter (TPM) concentrations, reaching 27.2 and 26.5 mg/m³, respectively. Their corresponding TPM emission factors were 2.24 × 10³ and 704 g/t. Metallurgical particulate emissions were dominated by PM_1–2.5 and PM₁, with PM_2.5/PM₁₀ ratios ranging from 0.59 to 0.86. The chemical composition exhibited pronounced size-dependent differences and strong process specificity. Crustal elements contributed more prominently to particles larger than PM_2.5, whereas water-soluble inorganic ions, organic carbon, and heavy metals were increasingly enriched in PM_1–2.5 and PM₁. Notably, tin smelting showed a clear decoupling between TPM emission intensity and PM₁-bound risk-related metal burden, indicating that conventional control strategies based solely on total particle mass may overlook fine-mode metal emission priorities.

High-frequency online water quality monitoring in large urban river systems is critical for fine-scale pollution control, early warning, and intelligent watershed management. However, non-stationary background variation and short-term fluctuations make reliable forecasting difficult. We developed a hybrid Fourier–EMA (FE)–TCN–Transformer framework to separate and model these dynamics. The FE module extracts multi-scale trend and seasonal background components through strictly forward feature engineering, while the TCN–Transformer captures short-term residual dynamics through local convolution and self-attention. Using the Huangpu River as a representative case, we constructed 20 forecasting tasks from high-frequency observations collected at four national monitoring sections during 2020–2024. The model produced single-step, 4-h-ahead forecasts for TN, TP, NH₃-N, COD_Mn, and DO. Under identical chronological data splits and evaluation procedures, the framework achieved the highest NSE and lowest RMSE in all 20 tasks among seven external baselines and three internal variants. Its mean NSE and RMSE were 0.839 and 0.181 mg/L, respectively, compared with 0.570 and 0.372 mg/L for PatchTST, the strongest external baseline by mean NSE. Relative to the internal Transformer baseline, mean NSE increased from 0.613 to 0.839 and mean RMSE decreased from 0.307 to 0.181 mg/L. These results show consistent performance across the evaluated sites and indicators. Integration into a prototype platform further demonstrated compatibility with continuous monitoring pipelines and fixed-cycle inference using pretrained parameters, supporting operational high-frequency water quality forecasting.

Stormwater runoff contains high levels of dissolved organic matter (DOM) that serve as precursors for disinfection byproducts (DBPs) during chlorination. The effect of advanced oxidation processes (AOPs) pretreatment on subsequent DBP formation remains uncertain, particularly under varying water matrices. Stormwater runoff from four functional zones (residential, commercial, transportation, and educational) was treated with three UV-based AOPs (UV/H₂O₂, UV/persulfate, and UV/ferrate), followed by chlorination. DOM transformation was characterized by dissolved organic carbon (DOC) removal, molecular weight (MW) distribution, hydrophobicity, and fluorescence indices. All three AOPs achieved > 87% DOC removal, near-zero aromaticity, and a shift of MW to < 1 kDa. However, subsequent chlorination revealed divergent DBP formation patterns governed by ammonia-nitrogen (NH₄⁺-N) concentration. In high-NH₄⁺-N runoff (residential and commercial, 15 and 6 mg/L), the ammonia-induced chlorine demand largely depleted free chlorine during post-chlorination, forming monochloramine as the dominant chlorinating agent. AOP converted DOM into low-MW intermediates that exhibited enhanced reactivity toward monochloramine, increasing both trihalomethanes (THMs, up to 6-fold) and haloacetonitriles (HANs, up to 10-fold). In low-NH₄⁺-N runoff (transportation and educational, 2–3 mg/L), free chlorine dominated and AOPs directly degraded DBP precursors, reducing both THMs (up to 65%) and HANs (up to 67%). Thus, high NH₄⁺-N drives a risk shift toward increased DBPs, whereas low NH₄⁺-N enables effective DBP control. These findings suggest that for high-NH₄⁺-N stormwater, ammonia pre-removal is advisable before AOP + chlorine, while for low-NH₄⁺-N runoff, AOPs alone can serve as an effective DBP control strategy.

Hydrogen peroxide (H₂O₂) is an eco-friendly oxidant widely used in clean synthesis, water treatment, and energy conversion. Graphitic carbon nitride (g-C₃N₄) has been explored as a photocatalyst for sustainable H₂O₂ production, but achieving high selectivity in pure water remains challenging. Here, a controllable vacancy-engineering strategy is developed to introduce nitrogen (N_V) and carbon vacancies (C_V) into g-C₃N₄ via alkali-assisted thermal treatment. The optimized C_V-g-C₃N₄ and N_V-g-C₃N₄ achieve remarkable H₂O₂ selectivity in the pure water increasing from 49.7% to 81.2% and 87.5%, with a surface-area-normalized H₂O₂ production rate of 65.3 μmol/(L·m²·h). Vacancies reshape the electronic structure by introducing defect states and shifting the N-2p p-band center upward. N_V generates shallow defect states that promote electron delocalization, favor end-on O₂ adsorption and lower the Gibbs free energies for *OOH formation, thereby promoting selective two-electron oxygen reduction reaction (2e^– ORR). In contrast, C_V forms deeper defect states that strengthen H₂O adsorption and reduce the Gibbs free energies for *OH formation, enabling a coupled 2e^– ORR and two-electron water oxidation reaction (2e^– WOR) pathway. This study elucidates the distinct redox roles of Nv and C_V in photocatalysis and provides a vacancy-engineering blueprint for designing efficient, metal-free photocatalysts toward sustainable H₂O₂ generation.

The degradation of sulfonamide pollutants in high-salinity wastewater is hindered by chloride radicals scavenging hydroxyl radicals. This study aims to achieve efficient degradation of sulfonamides in high-salinity wastewater by enabling a mechanistic switch from hydroxyl radicals (^•OH) to singlet oxygen (¹O₂). To this end, we fabricated MMFeP-800 °C porous carbon spheres via in-situ growth of MIL-100(Fe) on a MET 6/PVDF/PVP substrate followed by carbonization. In the low-temperature plasma system, we selected nine different types of target pollutants and found that the catalyst was particularly effective toward sulfonamide pollutants. This is attributed to (i) the Fe/N-doped catalyst inducing the generation of ¹O₂, which enhances the efficient removal of sulfonamide pollutants; (ii) the in-situ growth strategy ensuring full exposure of active components and accelerating interfacial reactions; and (iii) the high-salinity background itself, under plasma action, also promoting the ^•OH→¹O₂ conversion, producing a synergistic benefit. Quenching experiments, LC–MS, and DFT calculations elucidated degradation pathways. Cycling tests and biotoxicity assays demonstrated good stability and reduced toxicity, confirming the catalyst's practical potential. This work provides a promising strategy for treating high-salinity wastewater containing sulfonamides.

Continuous-flow anammox granulation requires effective biomass retention together with sufficient hydrodynamic selection, yet how their balance governs granule development remains unclear. Two continuous stirred-tank reactors with height-to-diameter ratios of 5.17 and 2.30 were operated under comparable loading conditions, and multiphase CFD was integrated with rheological, EPS, surface-interaction, and microbial analyses. At 150 r/min, the power density and mean turbulent dissipation rate in R1 were 2.05 and 2.77 times those in R2, respectively, although both reactors developed similar particle sizes and mechanical strengths by day 92. Thereafter, their trajectories diverged. Increasing R1 to 180 r/min enhanced axial suspension and hydrodynamic selection, accompanied by moderate particle growth to 412.34 μm and an increase in storage modulus to 23.43 kPa. R1 also exhibited a protein-rich tightly bound EPS matrix, favorable interparticle interactions, and sustained enrichment of Candidatus Kuenenia. In contrast, reducing R2 to 120 r/min improved biomass retention but weakened hydrodynamic selection, resulting in rapid particle enlargement to 537.59 μm, while the storage modulus declined to 10.93 kPa and anammox bacterial dominance decreased. These responses defined two distinct trajectories, namely selection-driven mechanical maturation in R1 and retention-driven aggregate enlargement in R2. Granule maturation therefore depended on coordinated particle growth, mechanical consolidation, and functional enrichment rather than particle enlargement alone. For engineering applications, mixing intensity should be selected according to reactor-specific suspension and biomass-retention requirements rather than prescribed as a fixed stirring rate.

Nanoscale zero-valent iron (nZVI) is widely investigated for environmental remediation but aggregation, poor transport, and unstable interfacial reactivity continue to limit its practical deployment. This perspective examines nanocellulose (NC) not simply as a stabilizer, but as an interfacial platform that can tune nZVI nucleation, dispersion, transport and redox behavior across multiple length scales. The importance of interfacial stabilization is illustrated by the reported decrease in the interaction energy barrier of nZVI from 124.2 kBT in deionized water to 31.6 kBT under groundwater conditions. We discuss how coordination chemistry, surface charge, and hierarchical confinement influence iron nucleation, particle dispersion, and surface accessibility, while emphasizing that improved stability does not necessarily translate into higher reactivity. CNC, CNF, and BNC are then considered as complementary platforms for electrosteric transport control, macroscopic formability and continuous-flow operation, and biocompatible iron–support interfaces, respectively. Finally, we discuss how groundwater chemistry, scalable processing, manufacturing cost, and life-cycle performance affect practical implementation. Together, these considerations provide a framework for designing nZVI@NC systems that balance particle stabilization, reactive surface accessibility, and application-specific requirements.