Search Results (258)

The purpose of this study was to investigate the effectiveness and mechanism of iron-based catalysts in the treatment of phenolic wastewater by catalyzing ozone oxidation. The removal rates of phenolics and COD were systematically examined using simulation experiments with water and actual wastewater, which involved analyzing the effects of reaction time, pH, ozone dosage, catalyst dosage, and initial concentration. The phenol and COD removal rates in the simulated wastewater were 95.9% and 93.5%, respectively, respectively, while the ozone dosage was 16 mg/L/min, pH was 6.7–6.8, and catalyst dosage was 0.3 g/L. The phenol and COD removal rates in the actual wastewater were 68.6% and 68.0%, respectively. The reaction time was 30 min. The system’s efficient removal ability for phenolic compounds, polycyclic aromatic hydrocarbons, and others was confirmed through three-dimensional fluorescence and ultraviolet spectroscopy. The iron-based catalyst generates ·OH through three pathways: adsorption of activated ozone on surface active sites, continuous production of free radicals by Fe²⁺/Fe³⁺ cycling, and direct activation of ozone by Fe²⁺. This mechanism analysis showed that the catalyst generates ·OH. These pathways convert pollutants into small molecules or mineralized by attacking the aromatic rings and conjugated structures of pollutants. Technical references for the deep treatment of phenol-containing wastewater are provided in this study. Full article

Metformin (MET) is a widely prescribed pharmaceutical compound used for the management of glucose levels and body weight. However, it is only partially metabolized in the human body, and a significant fraction is excreted unchanged, leading to its frequent detection in aquatic environments. Consequently, the removal of MET from wastewater has become a matter of increasing concern due to its potential impact on aquatic ecosystems. Furthermore, as a nitrogen-containing compound, MET has been extensively employed as a model pollutant to evaluate the performance of physical and chemical treatment technologies for pharmaceutical contaminants. This review aims to critically assess and summarize the efficiency and key limitations of various processes applied for MET removal. The reviewed approaches include physical–chemical treatments such as adsorption; biological treatments (activated sludge, biofiltration and phytoremediation), which rely on microbial metabolic activities or plant uptake to degrade or sequester metformin; and advanced oxidation processes (AOPs), such as ozonation, photolysis, photocatalysis, Fenton, and photo-Fenton systems. The efficiency of MET removal and mineralization is strongly dependent on the treatment method employed. Among the evaluated processes, the photo-Fenton reaction emerges as one of the most promising technologies, achieving high removal efficiencies under both ultraviolet (UV) and visible (Vis) irradiation. Full article

We present the first results of polar mesospheric cloud (PMC) detection using ultraviolet observations from TROPOMI (TROPOspheric Monitoring Instrument). An improved retrieval algorithm, developed on the basis of the SBUV-type approach and adapted to TROPOMI UV1 (270–300 nm) measurements, combines spatial binning, iterative Rayleigh background modeling, and adaptive thresholding to extract PMC signals from the background atmosphere. The robustness of the TROPOMI retrievals is evaluated through multi-scale comparisons with PMC data from the Cloud Imaging and Particle Size experiment (CIPS) and the Ozone Mapping and Profiler Suite Nadir Profiler (OMPS-NP). Compared with CIPS, the two datasets show broadly consistent hemispheric-scale horizontal structures and a westward wave-like phase progression consistent with possible quasi-5-day planetary-wave modulation, despite local-time differences. Compared with OMPS-NP, residual albedo under matched spatiotemporal conditions shows strong agreement for bright PMCs, whereas differences in spatial resolution lead to discrepancies in the detection of faint clouds. Seasonal-scale comparisons of PMC occurrence frequency also show consistent variability among the datasets. These results demonstrate that TROPOMI can resolve PMC structures smaller than 250 km that are difficult to detect with current low-resolution instruments. TROPOMI therefore provides a bridge between long-term coarse-resolution records and high-resolution observations, offering valuable data for studies of mesospheric dynamics and climate change. Full article

The Ozone Monitor Suite-Nadir (OMS-N) onboard the FY-3F satellite is a key payload for global atmospheric ozone and trace gas detection. The data quality depends on the accuracy of ground calibration. This study presents a systematic ground calibration of OMS-N. The instrument operates over 250–500 nm, with a spatial resolution of 7 × 7 km² and a spectral resolution of 0.5–1 nm. Radiometric calibration was performed using an integrating sphere, spectral calibration using a tunable laser, and geometric calibration using a precision turntable. All tests were conducted under controlled environmental conditions (20 ± 3 °C and 50% ± 10% humidity). The absolute radiometric calibration uncertainty was below 2.33% for UV1/UV2 and 1.69% for VIS, with relative uncertainties ≤1.84%. The spectral wavelength error was ≤0.01 nm for the VIS channel and ≤0.03 nm for the UV1/UV2 channels, and the geometric positioning uncertainty was better than 0.1 pixels. All performance indicators met or exceeded the design requirements. These results provide technical support for the quantitative application of OMS-N data in atmospheric monitoring and establish a reference framework for the ground calibration of similar ultraviolet hyperspectral instruments. Full article

Both the 27-day and the 11-year solar cycles of extreme ultraviolet radiation (EUV) influence the Earth’s middle atmosphere. The influences of solar cycles on geopotential height (or pressure) are analysed by using the Aura Microwave Limb Sounder (Aura/MLS) observations from 2004 to 2021. Composite analysis shows that the mesospheric 27-day variation in the global mean geopotential height is correlated with the 27-day variation of solar radio flux (F10.7 cm index), which is a proxy of solar EUV. The maximum of the geopotential height has a phase lag of 4 days with respect to the maximum of EUV. The 11-year solar cycle has a sensitivity of 492 m/100 sfu in global mean geopotential height at about 94 km high. Similarly, the influences of solar cycles on the global means of middle atmospheric temperature, ozone, and water vapour are derived and discussed. Full article

Surface ozone monitoring remains challenging due to sparse ground networks and limited satellite boundary-layer sensitivity. This study evaluates, for the first time, China’s Environmental Trace Gases Monitoring Instrument II (EMI-II) for estimating surface ozone over the Beijing–Tianjin–Hebei (BTH) region. EMI-II total ozone columns (TOCs) are retrieved using the differential optical absorption spectroscopy (DOAS) algorithm and validated against the TROPOspheric Monitoring Instrument (TROPOMI) (R = 0.96), Geostationary Environment Monitoring Spectrometer (GEMS) (R = 0.97), and the World Ozone and Ultraviolet Radiation Data Centre (WOUDC) ground measurements (R > 0.92, bias < 4%). TOCs are then combined with ERA5 meteorology, satellite NO₂/HCHO, and surface observations within machine learning models, achieving cross-validated R² of 0.94 and RMSE of 12.05 μg/m³ for surface ozone estimation. EMI-II estimates show strong agreement with independent observations (R = 0.91, RMSE = 10.83 μg/m³) and reproduce seasonal gradients, with summer concentrations (131 μg/m³) more than double winter levels (61 μg/m³). Estimation skill is regime-dependent: performance comparable to TROPOMI occurs under strong photochemical activity, while reduced sensitivity occurs under weak radiation and stable boundary layers—consistent with averaging kernel diagnostics. This first comprehensive validation demonstrates that EMI-II, despite vertical sensitivity limitations, provides meaningful surface ozone constraints under favorable atmospheric conditions. The framework is potentially applicable to other regions and sensors under similar conditions, providing a case study for integrating national satellite products into multi-source surface ozone estimation. Full article

Increasing water demand and the rising complexity of wastewater matrices, driven by pharmaceuticals, personal care products, and recalcitrant industrial contaminants, require advanced catalytic solutions capable of efficient mineralization under sustainable conditions. Solar-driven processes have attracted growing attention; however, ultraviolet disinfection, heterogeneous photocatalysis, and photo-Fenton systems are commonly treated as independent approaches without mechanistic integration. This review presents a unified photonic–thermal catalytic framework for solar-driven wastewater treatment, emphasizing the interplay between photon absorption, charge-carrier separation, reactive oxygen species generation, and radical-mediated oxidation pathways. The contributions of ultraviolet, visible, and infrared radiation are analyzed in terms of catalyst activation, persulfate and ozone activation mechanisms, and temperature-enhanced reaction kinetics governed by Arrhenius behavior. Particular attention is given to photothermal effects that modulate surface reaction rates, mass transfer, and catalyst stability. By integrating mechanistic insights with reactor-level considerations, this work provides a rational basis for the design of robust solar catalytic systems with enhanced activity, selectivity, and scalability for real wastewater applications. Full article

Hospital wastewater (HWW) carries a high and variable burden of pathogenic microorganisms, along with a diverse spectrum of emerging contaminants, such as pharmaceutically active compounds (PhACs) and antimicrobial resistance (AMR) determinants, posing significant challenges to conventional municipal treatment systems. The COVID-19 pandemic intensified the global use of disinfection technologies for infection control, inadvertently leading to the generation and release of novel classes of disinfection by-products (DBPs) and transformation products (TPs). These emerging by-products, alongside the persistent release of pharmaceuticals and AMR elements, have exposed critical limitations in conventional and advanced disinfection processes when applied to such complex matrices. This review synthesizes recent literature on disinfection-oriented advanced treatment strategies and other contaminants of emerging concern in hospital effluents worldwide. The discussed technologies include chlorine-based disinfection (e.g., free chlorine and chlorine dioxide), ozonation, ultraviolet irradiation (UV), electrochemical disinfection (ECD), nanomaterial-enabled disinfection, and combined multi-barrier schemes. While real-time monitoring of key compounds in HWW is increasingly feasible, critical bottlenecks remain: culture-based indicators may underestimate viable but non-culturable populations, molecular assays quantify genes without directly reflecting infectivity or transfer potential, and complex matrices hinder methodological harmonization. Future efforts should prioritize risk-based multi-barrier design, activity-informed monitoring, and intelligent process control to achieve robust co-mitigation of pathogens, PhACs, and AMR while minimizing disinfection by-products (DBPs) and life-cycle energy consumption. Full article

Microbial contamination of table eggs remains an important food safety concern, largely due to the presence of Salmonella spp. on eggshell surfaces and the potential for cross-contamination along the collection, grading, and packing chain. Conventional sanitation practices, including chlorinated-water washing, can reduce surface microbial loads but may also present limitations related to cuticle alteration, process variability, water use, and the risk of recontamination when operational conditions are not tightly controlled. This review synthesizes evidence on non-thermal and selected mild thermal technologies for the surface decontamination of intact table eggs, including ultraviolet-C (UV-C) irradiation, pulsed light, ozone-based treatments (gas and microbubble systems), non-thermal plasma, plasma-activated water, and gas-phase hydroxyl radical processes. For each approach, antimicrobial performance is discussed alongside effects on eggshell integrity, cuticle preservation, and key quality indicators (e.g., Haugh unit, albumen pH, yolk color, and shell strength). Particular attention is given to industrial constraints that influence real-world performance, such as treatment uniformity and shading effects, humidity dependence, line speed, equipment integration, and validation criteria. A shared limitation of surface treatments is their inability to inactivate pathogens that have penetrated shell membranes or contaminated egg contents, underscoring the need to align technology selection with the targeted hazard and the regulatory context. Thus, available data indicate that non-thermal technologies can contribute to reducing eggshell contamination when properly optimized, although broader implementation will depend on standardized operating parameters, robust process validation, and regulatory acceptance within existing egg processing systems. Full article

Candidozyma auris is an emerging multidrug-resistant yeast that readily contaminates healthcare environments, persisting on dry surfaces and enabling transmission and difficult-to-control outbreaks. A systematic review of environmental hygiene interventions targeting C. auris was conducted, focusing on efficacy against planktonic cells and surface-associated biofilms (including dry-surface biofilms, DSB where available). PubMed and Scopus were searched for English-language records published from 1 January 2017 to 30 September 2025, and study selection followed PRISMA 2020. Thirty-six studies from nine countries met the inclusion criteria. These were predominantly laboratory efficacy evaluations using carrier/suspension or quantitative surface methods reporting log₁₀ Colony Forming Unit (CFU) reductions; only seven studies assessed biofilm-associated C. auris. Across clades I–IV, chlorine-based disinfectants and oxidizing chemistries (hydrogen peroxide/peracetic acid formulations) most consistently achieved high-level reductions (often ≥ 5 log₁₀ CFU) under label-relevant conditions. In contrast, products containing only quaternary ammonium compounds (QACs) frequently underperformed and demonstrated greater variability. No-touch methods, particularly 254 nm ultraviolet-C light (UV-C), provided meaningful adjunctive reductions, but were highly dependent on dose delivery and geometry, and evidence for ozone-based approaches was mixed. Limited data on C. auris DSBs suggest planktonic testing may overestimate real-world conditions and underscore the importance of endpoints, such as transfer prevention and regrowth suppression. Full article

Drinking-water treatment systems must effectively control natural organic matter (NOM), a major precursor of regulated disinfection by-products (DBPs). Specific ultraviolet absorbance (SUVA) is widely used as an operational surrogate for NOM aromaticity and hydrophobicity; however, ozonation and subsequent filtration can disrupt the linear relationship between SUVA and trihalomethane formation potential (THMFP). This study evaluates whether SUVA can reliably predict THMFP under two ozonation configurations frequently applied in drinking-water treatment: pre-ozonation prior to coagulation–filtration and final ozonation following filtration. Experimental data were analyzed using conventional linear regression and artificial neural network (ANN) models, with SUVA employed as the sole predictor variable. Across all treatment configurations, reductions in SUVA were consistently more pronounced than corresponding decreases in THMFP, indicating a decoupling between chromophoric loss and chlorine-reactive precursor dynamics under ozonation-dominated conditions. Linear regression models exhibited only moderate predictive performance (R² = 0.63–0.76), reflecting the limitations of proportional surrogate-based approaches when NOM undergoes oxidative and adsorptive transformation. In contrast, single-parameter ANN models captured the nonlinear SUVA–THMFP relationship with substantially higher accuracy across both pre- and final-ozonation regimes (R² = 0.88–0.99), successfully resolving process-dependent patterns embedded within optically compressed SUVA signals. These findings demonstrate that, although SUVA alone cannot linearly represent the multistep transformation of NOM during ozonation and adsorption, it retains process-relevant structure information on DBP precursor reactivity that can be effectively extracted using nonlinear modelling. The results highlight the potential of integrating ANN-driven tools into advanced monitoring and DBP-control strategies in modern drinking-water treatment systems. Full article

This study is devoted to investigating the effect of aerosols on solar UV radiation. In the ultraviolet range, scattering processes are dominant and lead to a substantial contribution of diffuse UV radiation to the global UV irradiance. The paper introduces a method for estimating solar UV Index. The proposed method is first compared with other UV Index estimation methods and is subsequently applied to examine the influence of aerosols and ozone on solar UV radiation and on its diffuse component. Human skin exposure to diffuse solar UV radiation can be potentially harmful to health. Full article

Acrylic resins are commonly used for denture bases due to ease of molding but are prone to water absorption and microbial contamination. This study aimed to evaluate the effects of ozonated water immersion (OZ), ultrasonic cleaning (US), and ultraviolet (UV) irradiation on the removal of Candida albicans from acrylic resins produced by heat curing and additive manufacturing. The resin specimens were then subjected to treatment with OZ, US, UV irradiation, and commercial denture cleansers. Following treatment, the number of viable C. albicans cells was quantified and statistically analyzed (α = 0.05), morphology was observed under a scanning electron microscope (SEM) and fluorescence imaging. OZ, US, and UV irradiation significantly reduced the viable C. albicans count. Notably, the combination of the three treatments achieved a reduction exceeding 99.9% of viable cells. Although SEM revealed that C. albicans remained on the specimens, fluorescence imaging demonstrated a progressive decrease in viable cells and an increase in dead cells with each treatment, with the greatest effect observed when the three treatments were combined. The difference of removal behaviors of C. albicans among fabrication methods was not observed, comparable to denture cleaners. The combined application of all three treatments was the most effective strategy for microbial removal. Full article

Background/Objectives: Environmental contamination of dental surfaces is a major vector for cross-infection. Ultraviolet-C (UVC) irradiation provides rapid, chemical-free decontamination; however, depending on wavelength and ventilation conditions, ozone generation may occur. This study evaluated the germicidal efficacy of UVC on three high-touch surfaces: a wooden work table, a stainless-steel consumables table, and a dental unit table. Methods: Surfaces were sampled at baseline, after 5 min (27 mJ/cm²), and after 10 min (54 mJ/cm²) of UVC exposure at 90 µW/cm². Colony-forming units (CFU/cm²) were enumerated using Mueller–Hinton agar. Results: UVC achieved >99% reduction after 5 min and complete elimination after 10 min. Material properties (porosity, reflectivity, and grooves), along with quantified parameters like surface roughness (Ra) and contact angle, influenced minor differences in decontamination. Conclusions: Used with appropriate safety protocols, short-duration UVC irradiation effectively decontaminates dental surfaces and can complement chemical disinfection. Future studies must incorporate artificially soiled surfaces, biofilms, and emerging far-UVC/UV-LED technologies. Full article

Catalytic ozonation has been widely utilized in environmental applications, such as the removal of pharmaceutical active compounds (PHACs) from wastewater, due to its outstanding catalytic efficiency. To further enhance its performance and expand its practical application, ozone-based hybrid processes have been investigated, including ultraviolet radiation/ozonation, hydrogen peroxide/ozonation, ultrasonication/ozonation, and biological treatment/ozonation. Ozone degrades pollutants via two primary pathways: direct oxidation (via molecular ozone) and indirect oxidation (via reactive intermediates). Enhancing ozone decomposition into various reactive oxygen species (ROS), predominantly hydroxyl radicals, can significantly augment the degradation efficiency of pollutants. The surface adsorption and electron transfer processes of catalysts can promote ozone activation and decomposition into ROS to achieve the efficient degradation and mineralization of pollutants. Among catalysts, Mn-based catalysts have been extensively studied in past research. They have demonstrated exceptional performance when combined with other metals, such as Mn/Ce, Mn/Fe, and Mn/Co, etc., due to synergistic effects arising from bimetallic interactions. The inherent characteristics of catalyst supports may also influence the generation process of ROS. Choosing an appropriate support is conducive to promoting the uniform distribution of catalytic active sites on the catalyst surface and avoiding the agglomeration of metal particles, and it is also beneficial for the recovery and reuse of the catalyst. Furthermore, coupling catalytic ozonation processes with techniques like high-gravity technology, jet reactor systems, and micro–nano-bubbles can improve the utilization efficiency of ozone by exploiting gas cavitation effects. In this paper, we summarize the research progress in the degradation of PHACs using catalytic ozonation and discuss strategies for improving the mass transfer efficiency of ozone in water. Finally, the challenges and opportunities associated with applying catalytic ozonation in practical applications are also discussed. Full article