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The development of highly efficient and selective ozonation catalysts is crucial for enhancing the treatment of nitrogen-containing wastewater. In this study, a Co/Mg(OH) 2 nano-hexagonal sheets ozonation catalyst was prepared by one-pot hydrothermal method, and the structural characteristics of this catalyst were comprehensively analyzed. The O Sur /O ratio of this catalyst was 41.06 %. Under the optimal conditions (22 ℃, initial pH of 9.0, ozone dosage of 1.2 mg/L, catalyst dosage of 1.0 g/L, initial NH 3 -N concentration of 10.00 mg/L), NH 3 -N and total nitrogen (TN) removal efficiencies of 90.26 % and 63.44 % were respectively obtained, and the removal process exhibited pseudo-first-order kinetics. Moreover, at 4 ℃, the NH 3 -N and TN removal efficiencies reached 95.49 ± 1.14 % and 65.61 ± 1.13 %. In a co-degradation process for the removal of both N and C, the ammonia and most organic compounds competed for active substances, but both pollutants were effectively removed. Hydroxyl radicals (•OH) were the main active substance involved in NH 3 removal. However, the massive loss of Mg2+ experienced after three cycles reduced the NH 3 -N and TN removal efficiencies to 31.83 % and 6.55 %, respectively. Finally, the electron transfer generated by the variable-valence Co ion was determined to promote the selectivity of the reaction toward gaseous N products. These findings offer promising avenues for the development of more energy-efficient and effective nitrogen removal processes. [Display omitted] • Nano Co/Mg(OH) 2 catalysts were facilely synthesized via one-pot solvothermal method. • Co/Mg(OH) 2 inspired by O 3 showed great NH 3 removal and selectivity to Gas-N. • •OH was the dominant active species on NH 3 degradation. • The production of Co3+/Co2+ increased the concentration and migration of electrons. • N transformation mechanism in the catalytic ozonation upon Co/Mg(OH) 2 was proposed. [ABSTRACT FROM AUTHOR]

Heterogeneous catalytic ozonation (HCO) enables the destruction of organic pollutants in wastewater via oxidation by powerful hydroxyl radicals (·OH). However, the availability of short‐lived ·OH in aqueous bulk is low in practical treatment scenarios due to mass transfer limitations and quenching of water constituents. Herein, we overcome these challenges by loading MgO catalysts inside the pores of a tubular ceramic membrane (denoted as CCM) to confine ·OH within the nanopores and achieve efficient pollutant removal. When the pore size of the membrane was reduced from 1000 to 50 nm, the removal of ibuprofen (IBU) by CCM was increased from 49.6 % to 90.2 % due to the enhancement of ·OH enrichment in the nanospace. In addition, the CCM exhibited high catalytic activity in the presence of co-existing ions and over a wide pH range, as well as good self-cleaning ability in treating secondary wastewater. The experimental results revealed that ·OH were the dominant reactive oxygen species (ROS) in pollutant degradation, while surface hydroxyl groups were active sites for the generation of ·OH via ozone decomposition. This work provides a promising strategy to enhance the utilization of ·OH in HCO for the efficient degradation of organic pollutants in wastewater under spatial confinement. [Display omitted] • MgO-loaded catalytic ceramic membranes were prepared. • Spatial confinement enriched ·OH to enhance HCO for efficient pollutant removal. • ·OH was the dominant reactive oxygen species in pollutant degradation. • The surface hydroxyl groups of MgO promoted ·OH generation via ozone decomposition. • The CCM system showed stable degradation efficiency and self-cleaning property. [ABSTRACT FROM AUTHOR]

Degradation of organics in high-salinity wastewater is beneficial to meeting the requirement of zero liquid discharge for coking wastewater treatment. Creating efficient and stable performance catalysts for high-salinity wastewater treatment is vital in catalytic ozonation process. Compared with ozonation alone, Mn and Ce co-doped γ -Al 2 O 3 could remarkably enhance activities of catalytic ozonation for chemical oxygen demand (COD) removal (38.9%) of brine derived from a two-stage reverse osmosis treatment. Experimental and theoretical calculation results indicate that introducing Mn could increase the active points of catalyst surface, and introducing Ce could optimize d -band electronic structures and promote the electron transport capacity, enhancing HO• bound to the catalyst surface ([HO•] ads) generation. [HO•] ads plays key roles for degrading the intermediates and transfer them into low molecular weight organics, and further decrease COD, molecular weights and number of organics in reverse osmosis concentrate. Under the same reaction conditions, the presence of Mn/ γ -Al 2 O 3 catalyst can reduce ΔO 3 /ΔCOD by at least 37.6% compared to ozonation alone. Furthermore, Mn-Ce/ γ -Al 2 O 3 catalytic ozonation can reduce the ΔO 3 /ΔCOD from 2.6 of Mn/ γ -Al 2 O 3 catalytic ozonation to 0.9 in the case of achieving similar COD removal. Catalytic ozonation has the potential to treat reverse osmosis concentrate derived from bio-treated coking wastewater reclamation. [Display omitted] [ABSTRACT FROM AUTHOR]

The purpose of the study was to evaluate the effects of using of ozonation to remove antibiotics used, among others, in veterinary medicine, from the aqueous environment. The effect of this process on the degradation, mineralisation and ecotoxicity of aqueous solutions of ampicillin, doxycycline, tylosin, and sulfathiazole was investigated. Microbiological MARA® bioassay and two in silico methods were used for the ecotoxicity assessment. Ozonation was an effective method for the degradation of the antibiotics studied and the reduction in ecotoxicity of the solutions. However, after ozonation, the solutions contained large amounts of organic products, including compounds much less susceptible to ozonation than the initial antibiotics. Structures of 14, 12, 40 and 10 degradation products for ampicillin, doxycycline, tylosin, and sulfathiazole, respectively, were proposed. It was confirmed that ozone plays a greater role than hydroxyl radicals in the degradation of these antibiotics, with the exception of TYL. The use of ozonation to obtain a high degree of mineralisation is unfavourable and it is suggested to combine ozonation with biodegradation. The pre-ozonation will cause decomposition of antibiotic pharmacophores, which significantly reduces the risk of spread of antimicrobial resistance in the active biocenosis of wastewater treatment plants. [Display omitted] • During ozonation, the degradation efficiency of antibiotics was approximately 100%. • Ozonation was not an effective method of mineralising antibiotics. • Ozonation products were less ecotoxic than the initial antibiotics solutions. • Main cause of antibiotics degradation was a direct reaction with ozone. • Direct ozonation requires the presence of sensitive moieties in the organic molecules. [ABSTRACT FROM AUTHOR]

Based on the efficiency of the catalytic ozonation techniques (HDWS+O 3 and MnFe 2 O 4 @SBC+O 3) in enhancing the sludge dewaterability, the effectiveness in synchronized abatement antibiotics and antibiotic resistance genes (ARGs) was conducted to determine. The results revealed that catalytic ozonation conditioning altered the distribution of target antibiotics (tetracycline (TC), oxytetracycline (OTC), norfloxacin (NOR), ofloxacin (OFL)) in the dewatered filtrate, the dewatered sludge cake and the extra-microcolony/cellular polymers (EMPS/ECPS) layers, achieving the redistribution from solid-phase adsorption to liquid-phase dissolution. The total degradation rate was over 90% for TC and OTC, 72–78% for NOR and OFL; the abatement efficiency of eleven ARGs reached 1.47–3.01 log and 1.64–3.59 log, respectively, and more than four eARGs were eliminated. The effective abatement of the absolute abundance of Mobile genetic elements (MGEs) (0.91–1.89 log) demonstrated that catalytic ozonation conditioning could also significantly inhibit horizontal gene transfer (HGT). The abundance of resistant bacteria was greatly reduced and the signal transduction of the typical ARGs host bacteria was inhibited. The highly reactive oxidation species (ROS) generated were responsible for the abatement of antibiotics and ARGs. These findings provided new insights into the sludge conditioning for ideal and synchronized reduction in volume and hazardousness by catalytic ozonation processes in sludge treatment. [Display omitted] • Catalytic ozonation conditioning WAS achieved synchronized volume and harm reduction. • The total degradation rate was over 90% for TC and OTC, and 72–78% for NOR and OFL. • ARGs abatement rate reached 1.47–3.59 log and more than four eARGs were eliminated. • MGEs abatement rate reached 0.91–1.89 log, HGT was blocked and hosts were reduced. • The generated ·OH, O 2 ·- and 1O 2 were contributed to antibiotics and ARGs abatement. [ABSTRACT FROM AUTHOR]

While the occurrence and removal technologies of tetracyclines in the environment have been reported, a comprehensive systematic summary and analysis remain limited, especially for new generations compounds such as doxycycline. In this review, the latest information regarding the distribution of various tetracyclines in different countries over the past seven years (2017–2023) reveals a notable absence of research reports in North America and Oceania. With China as the representative country, the investigation indicates that the maximum concentrations of TCs exceed 5 µg/L. The maximum concentration of tetracyclines in feces (26.22 µg/L) can reach one order of magnitude higher than that in other media. Furthermore, advanced oxidation technologies, such as Fenton processes, electrochemical oxidation, photolysis, ozonation, etc., were also examined, and the median degradation rate achieved 91.9–97.67%. Reactions such as methylation, demethylation, hydroxylation, dehydration, ring cleavage, and oxidation were observed during degradation. The most common intermediate product was identified as m/z = 461 (C 22 H 25 N 2 O 9). This review indicates that future efforts should emphasize understanding the occurrence and fate of new-generation tetracyclines in the environment. [Display omitted] • The global distribution of detected tetracyclines over 7 years is displayed. • In-situ and ex-situ removal techniques for tetracyclines are discussed. • Combined advanced oxidation processes excel in complex tetracyclines wastewater. • The m/z = 461 (C 22 H 25 N 2 O 9) is a key intermediate in tetracyclines degradation. [ABSTRACT FROM AUTHOR]

Targeted removal of three key refractory toxic organic compounds (TOMs) in 2-butenal manufacturing wastewater (2-BMW) is critical for enhancing pre-treatment by hydrolysis acidification (HA). We investigated the pre-treatment of 2-BMW with HA, coupled with ozonation in this study. Our results indicated that the removal rate of these key TOMs and the detoxification rate reached almost 100% and 46.3%, respectively, by ozonation under only 0.099 mg O 3 /mg chemical oxygen demand (COD). The organic load rate (OLR) reached 10.25 ± 0.43 kg COD/m3·d, and the acidification degree (AD) and detoxification efficiency reached 56.0% and 98.3%, respectively, with enhancements of 35.1% and 55.2%, respectively, compared with HA alone. The removal rate of the three key TOMs was improved by > 75%. The degradation pathways of these key TOMs were ring cleavage and ester formation by ozonation, followed by fermentation and acid production by HA. Ultimately, the synergistic role of ozonation and HA was revealed. The preferential cleavage of these key TOMs by ozonation was achieved because of their high electron cloud density and multiple reaction sites, which generated more fermentation-friendly products. The fermentation and acid production reactions may be directly involved in these products. Functional bacteria and key metabolic pathways were also enhanced by ozonation. [Display omitted] • Pre-treatment of 2-BMW was enhanced by HA coupled with ozonation. • Targeted cleavage of key TOMs by pre-ozonation was achieved. • Ring-cleavage, esters formation, and fermentation were main pathways. • Fermentative bacteria and metabolisms were enriched. • Synergistic role of ozonation and HA was revealed. [ABSTRACT FROM AUTHOR]

• The selectivity to gaseous products of single ozonation of ammonia was proved to be pH dependent. • A new and possible mechanism for single ozonation of ammonia was proposed. • Catalytic ozonation over MgO was found to be able to decompose ammonia at low temperature (0–10℃). • MgO worked as a solid alkali as well as a catalyst to facilitate ammonia oxidation. Ozone oxidation and ozonation catalyzed with MgO were applied to remove ammonia in water at low temperature (10℃). Results show that pH played a critical role in both ozonation and catalytic ozonation for ammonia removal, especially in the ozonation rate of ammonia and the types of oxidation products. For single ozonation, both O 3 and OH contributed to ammonia degradation. Lower pH is beneficial to high selectivity of gaseous products (N 2 or N 2 O) in the presence of Cl−. Significantly enhanced efficiency of ammonia removal was obtained under the catalysis of MgO, which worked as a solid alkali as well as a catalyst, facilitating ammonia oxidation both in the solution and on the MgO surface. Molecular O 3 dominated ammonia removal in the heterogeneous catalytic ozonation system, while the contribution of OH was not significant in quantity and a small part of ammonia was degraded by the reaction of ClO x − with NH 4 +. A relatively high removal efficiency (77.53%˜80.17%) of ammonia could also be achieved in the temperature range of 0℃˜10℃, which indicates that catalytic ozonation over catalysts like MgO may be a potential method to control ammonia pollution during cold weather or under other conditions difficult for biological treatment. [ABSTRACT FROM AUTHOR]

• HAC greatly enhanced •OH generation at pH 4.0 ˜ 7.0 during ozonation. • Possible mechanisms for the generation of •OH and 1O 2 were elucidated. • Plausible degradation mechanism and pathways of PMT were proposed. • Kinetic model for the prediction of PMT removal was established. The decontamination of prometon (PMT) by ozone/hydroxylamine hydrochloride (O 3 /HAC) was systematically investigated in this study with focus on the degradation mechanism and kinetics. Experimental results revealed that there was an enhancement of PMT degradation efficiency by 42.1% and the pseudo-first-order rate constant by more than 5.7 times in O 3 /HAC process under low HAC dosage (5 mg L−1) after 3 min in comparison with O 3 alone. The second-order rate constant of PMT with hydroxyl radical (•OH) was determined to be (1.84 ± 0.1) × 109 M−1 s−1 and 7.80 × 109 M−1 s−1 via competition kinetics and •OH steady-state hypothesis, respectively. The PMT removal in O 3 /HAC process was highly pH-dependent and the optimum degradation performance was achieved under pH 5.0. In addition, •OH and singlet oxygen were identified as the primary reactive oxygen radicals in O 3 /HAC process. Meanwhile, eleven transformation products of PMT were identified and possible degradation mechanisms were proposed. Moreover, a kinetic model based on chemical kinetics and steady-state hypothesis was developed and modified to predict the PMT abatement in O 3 /HAC process. The results demonstrated that the O 3 /HAC process provided a promising alternative for refractory organic pollutants decontamination in water treatment. [ABSTRACT FROM AUTHOR]

• Cu-OMS x -T nanorods were prepared by the hydrothermal-calcination method. • First report on Cu incorporated into OMS-2 as highly efficient ozonation catalysts. • Cu-OMS 0.5 -140 exhibited the highest catalytic activity, stability and reusability. • Cu incorporation promoted the formation of multivalent metals and oxygen vacancies. • The plausible generation mechanism of ⋅OH and O 2 ⋅-was elucidated. A series of copper doped manganese oxide octahedral molecular sieves (Cu-OMS x -T) with different Cu/Mn ratios and hydrothermal temperatures were successfully synthesized and used for catalytic ozonation towards oxalic acid (OA) degradation. The as-prepared Cu-OMS x -T composites were comprehensively investigated by BET, FT-IR, XPS and etc. characterizations. The results indicated that the Cu doping would increase the specific surface area, change chemical bonds, and promote the transformation of multivalent metals and the generation of oxygen vacancies. It was noteworthy that the hydrothermal temperature played an important role in the morphology of Cu-OMS x -T composites and the Cu/Mn molar ratios greatly influenced the catalytic activities. Amongst, the Cu-OMS 0.5 -140 achieved the optimum catalytic activity with 97.3% of OA degradation efficiency and 98.8% of mineralization rate in 30 min at pH 6.0. Moreover, hydroxyl radical and superoxide radical were identified as the major reactive radicals and the catalytic mechanism for OA degradation enhancement was also elucidated. In addition, the Cu-OMS 0.5 -140 exhibited great stability and reusability with high OA mineralization rate (>90%) and low metal release after five times recycle. Overall, the results indicated that the synthesized Cu-OMS 0.5 -140 is an efficient, stable, and recyclable ozonation catalyst, and could be a promising alternative material for water purification. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Overhaul wastewater was treated with ozonation-microelectrolysis-ozonation process. • Microelectrolysis could destroy the structure of MDEA, but ozone had no effect. • The effects of operating parameters on MDEA removal were investigated. • The degradation mechanism of MDEA in microelectrolysis was discussed. Abstract In this study, the microelectrolysis system was applied to generate strong reductants, such as free hydrogen [H] and O ∙ , and thus removing N -Methyldiethanolamine (MDEA) in overhaul wastewater. Effects of initial influent pH, mass ratio of filings to wastewater, air aeration rate, and reaction temperature on the removal of MDEA were investigated intensively. Experimental results indicate that optimum removal rate of MDEA can be obtained at pH = 2, inlet air rate = 1 L min−1, mass ratio of filings to wastewater = 1:1 and temperature = 25 °C. About 96.0% Total Organic Carbon (TOC) in overhaul wastewater can be mineralized by ozonation–microelectrolysis–ozonation (OMIO) treatment process. By analyzing the effluent at various stages, it was established that microelectrolysis played a leading role in the destruction of MDEA. The degradation mechanism of MDEA has been clarified through detecting the degradation products with Gas Chromatography–Mass Spectrometer (GC–MS). Subsequently, ozone reacts with intermediate products generated by MDEA degration through OH· pathway under alkaline condition. In short, these results suggest that OMIO system should be proposed as a promising treatment process for the MDEA wastewater. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • GO-TiO 2 catalysts were synthetized and tested for photocatalytic ozonation. • Ozone processes completely remove Primidone from water in minutes. • TiO 2 becomes a visible active catalyst with GO and ozone. • Combination of ozone, GO-TiO 2 and visible light is needed for mineralization. • Catalyst reusability test shows high mineralization after 3 runs. Abstract A graphene oxide-titania (GO/TiO 2) composite was synthesized via sol-gel method, and studied in aqueous Primidone mineralization with ozone and LED visible light. The photocatalyst was characterized by different techniques (XRD, TEM, SBET, TGA, UV–vis diffuse reflectance spectroscopy). The band gap value decrease from 3.14 eV for bare TiO 2 samples to 2.5 eV in GO/TiO 2 composites clearly shows the interaction of GO with TiO 2 structure. Approximately 20 mg L−1 of Primidone was removed in less than 20 min if ozone was applied, regardless of the presence or absence of light and catalyst. However, reactivity tests show a synergism effect between photocatalysis and ozonation for mineralization purposes. The combination of ozone and GO improved the activation of TiO 2 under visible light. Process optimization led us to select a catalyst dosage of 0.25 g L−1, a light radiance of 359 W m−2 and a GO loading in the catalyst around 0.75%. At these conditions, with photocatalytic ozonation, the presence of GO in the catalyst improved mineralization up to 82% in 2 h compared to 70% reached with bare TiO 2. Catalyst reusability shows no decrease of photocatalytic activity. Scavenger tests point to hydroxyl radicals as the main species responsible for Primidone removal. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Highly dispersed CeO 2 on OCNT were synthesized and used as ozonation catalyst. • CeO 2 -OCNT exhibited excellent activity and stability for catalytic ozonation. • CeO 2 -OCNT possessed synergic effect between OCNT and CeO 2 for catalytic ozonation. • CeO 2 -OCNT enhanced ozone conversion intoOH. Abstract Heterogeneous catalytic ozonation, in which ozone is activated by various catalysts to produce reactive oxygen species (ROS), is an effective approach to degrade persistent organic pollutants in water. However, catalyst with high activity and good stability for catalytic ozonation still remains rare. In this work, a highly dispersed cerium oxide on oxidized carbon nanotubes (CeO 2 -OCNT) were prepared and characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction using hydrogen (TPR-H 2) experiments. The as-synthesized CeO 2 -OCNT showed significantly enhanced catalytic performance for degrading organic pollutants during catalytic ozonation. The removal efficiency of optimized CeO 2 -OCNT for phenol mineralization was 2–3 times of pure CeO 2 and OCNT, and was also better than that of a composite with the same composition, which demonstrated a synergic effect between OCNT and CeO 2 on CeO 2 -OCNT for catalytic ozonation. The TOC removal efficiency exhibited no obvious reduction after five cycling experiments, indicating the synthesized CeO 2 -OCNT possessed good reusability. Moreover, electron paramagnetic resonance (EPR) and radicals quenching experiments revealed that hydroxyl radicals (OH) were the dominant ROS for organic pollutants degradation. The superior activity of CeO 2 -OCNT for catalytic ozonation could be attributed to the well-dispersed CeO 2 , the improved mass transfer, and the facilitated redox Ce3+/Ce4+ cycling. [ABSTRACT FROM AUTHOR]

Highlights • Degradation of thirty pharmaceuticals with various structures was investigated. • The synergy effect of carboxylic and amide group were very significant. • Ozonation second-order rate constants and enhancement factors correlated well. Abstract The increasing amounts of pharmaceuticals in aqueous environment are found to be structurally diverse. O 3 has been demonstrated as a high effective agent in removing pharmaceuticals, however, O 3 is a very selective oxidant which is ineffective for some ozone refractory structures. Recently, a novel electrochemistry-based oxidation process (E-peroxone) has been developed by a simple combination of electrolysis and conventional ozonation process, which can produce a large amount of aqueous OH in situ. E-peroxone process can enhance the performance of conventional ozonation process. The purpose of this study was to investigate the elimination performance of thirty pharmaceuticals with various chemical structures including macrolide, quinolone, sulfonamides, tetracycline, carboxylic group, Naphthalene, Nitrogen-containing group, C C double bond in electrolysis, ozonation and E-peroxone process. Parent pharmaceuticals and TOC elimination were compared. By comparing different chemical groups, the synergy effect of pharmaceuticals with carboxylic and amide groups were significant, with average degradation level 98.7 ± 2.8% within 15 min. Degradation levels of some groups were quite efficient during both ozonation and E-peroxone process, such as macrolide, quinolone, sulfonamides and tetracycline. E-peroxone process improved the TOC and acute toxicity elimination efficiency of mixed pharmaceutical solutions significantly. Major operation parameters and cross correlation analysis were also evaluated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • For the first time, four Fe-MOFs are explored as catalysts for effective catalytic ozonation. • MIL-53(Fe) with the highest LAS and suitable porosity exhibits the highest catalytic activity. • MIL-53(Fe) shows good reusability and stability after successive 5 cycles. • Surface LAS of MIL-53(Fe) are the active sites for ozone adsorption and decomposition. • The catalytic ozonation mechanism of MIL-53(Fe) is proposed. Abstract Developing new heterogeneous catalysts has attracted much attention and is of significant importance for the efficient catalytic ozonation of organic pollutant. Herein, for the first time, we explored four environmental-benign iron-based MOFs (Fe-MOFs) for the catalytic ozonation reaction. These Fe-MOFs were characterized by PXRD, FT-IR, SEM, XPS, N 2 sorption-desorption isotherms and chemisorbed-pyridine IR. All Fe-MOFs show high catalytic performances with their intrinsic Lewis acid sites (LAS). Furthermore, MIL-53(Fe) demonstrates the highest catalytic activity because of its largest amount of LAS and suitable porosity-derived attractive mass-transfer property. The Rhodamine B (RhB) degradation kinetic rate is calculated to be 5.76 min−1 with MIL-53(Fe), while 1.82 min−1 with MIL-88B(Fe), 1.40 min−1 with MIL-101(Fe), 0.87 min−1 with MIL-100(Fe) and 0.43 min−1 of ozonation alone. The TOC removal in MIL-53(Fe)/O 3 system is 4 times higher than that of ozonation alone. MIL-53(Fe) displays acceptable reusability and stability after 5 cycles. Surface LAS of MIL-53(Fe) are the active sites for the ozone decomposition. Moreover, surface-adsorbed hydroxyl radical, superoxide radical and singlet oxygen are confirmed as the reactive oxygen species from ozone decomposition in MIL-53(Fe) suspension. This work offers new platforms for catalytic ozonation and may drive the development of MOFs-based catalytic ozonation for effective water treatment. [ABSTRACT FROM AUTHOR]

Highlights • Candida methanosorbosa BP-6 strain was used as an agent for ozonized rubber biodegradation. • Candida methanosorbosa BP-6 strain was able to degrade ozonized and non-ozonized rubber. • Ozonized rubber resulted in better metabolic condition of microorganisms. • FTIR and SEM analysis showed modifications of the rubber surface and structure appeared by yeast biodegradation. Abstract Aniline-degrading yeast strain - Candida methanosorbosa BP-6 was tested for its ability to degrade ground tire rubber, treated and non-treated with ozone. The protein content, respiratory activity, critical oxygen concentration (COC) and emulsifying activity of the yeast strain were monitored during 21 day degradation process. The effects of biodegradation were evaluated using aldehyde detection, Scanning Electrone Microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR) analysis. Pre-treatment of ground tire rubber with ozone resulted in lower microbial growth. However, metabolic condition of the C. methanosorbosa BP-6 yeast strain was higher in sample with ozonized tire rubber. Furthermore, the COC values in the last days of the process were about 30% lower regarding non-ozonized polymer. Also, the ozonization of tire rubber resulted in higher biosurfactant production of the yeast strain. The roughness and visible gaps in rubber matrix (SEM analysis) confirmed the ability of Candida methanosorbosa BP-6 yeast strain for tire rubber biodegradation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • NDMA formation from hydrazines during ozonation is initiated by hydrogen abstraction. • The C atom of the -N=C moiety in hydrazones is preferred to be attacked by ozone. • DMAN is an important intermediate in NDMA formation during ozonation. • The reactivity order in HA is -NH 2 > -N(CH 3) 2 > -CO-NH ∼ =C(CH 3) 2 > =CH-. • Formations of HOOOH, HOOH and HCOH in the ozonation of hydrazines were elucidated. Abstract N -nitrosodimethylamine (NDMA) as the most frequently detected disinfection by-product has aroused widespread concern due to its unusually high carcinogenicity, however, there is still limited understanding of its formation mechanisms. In this study, the formation mechanisms of NDMA from some typical hydrazines and hydrazones with high NDMA conversion yields (60%∼90%) during ozonation, i.e., unsymmetrical dimethylhydrazine (UDMH), 1-formyl-2,2-dimethylhydrazine (FDMH), formaldehyde dimethylhydrazone (FDH) and acetone dimethylhydrazone (ADMH), were investigated by using DFT method with the M05 functional. A new NDMA formation mechanism from hydrazines during ozonation was proposed, in which the initial step is hydrogen abstraction rather than previously reported oxygen addition. For hydrazones, the C atom of the -N = C moiety in hydrazones is preferred to be attacked by ozone to generate N,N-dimethylaminonitrene (DMAN), which is an important intermediate in NDMA formation during ozonation. Moreover, the reactivity order of the following H atoms in hydrogen/hydride ion abstraction (HA) by ozone is -NH 2 > -N(CH 3) 2 > -CO-NH ∼ =C(CH 3) 2 > =CH-. Additionally, formation pathways of some experimentally detected compounds, i.e., HOOOH, HOOH and HCOH, in the ozonation of hydrazine were elucidated in this study. The results are expected to expand our understanding of NDMA formation mechanisms and ozone reaction characteristics. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Dimethyl phthalate degradation was nearly completely inhibited by ozone in presence of Cu(II) ions. • Derepression of Cu(II) via the formation of Cu-EDTA in presence of EDTA was observed. • Interphase Cu-EDTA enhanced the removal of dimethyl phthalate remarkably. • Reaction of ozone and Cu-EDTA, organic nitrogen intermediates induced the sustained formation of OH. Abstract In this study, the presence of Cu(II) ions was found for the first time to severely inhibit +-dimethyl phthalate (DMP) degradation by ozone due to the formation of the stable complex Cu(II)-DMP. However, 100% DMP removal was rapidly reached when ethylenediamine tetraacetic acid (EDTA) was added with a Cu(II)/EDTA molar ratio of 3:1. Subsequent studies indicated that Cu(II)-DMP is sequestrated by EDTA, then DMP was degraded and Cu(II) was removed by precipitation. The freshly formed Cu-EDTA2− and organic nitrogen intermediates further decomposed O 3 into OH, which induced to the rapid degradation of DMP. The k obs of Cu-EDTA/O 3 were 9–10 times greater than the k obs of DMP removed by ozonation alone within 10 min. The reaction mechanism involved a OH generation was proposed. The OH and O 2 - are generated from the rapid reaction between ozone and EDTA. Acting as a more strongly negative species, the specific Cu(II) in Cu-EDTA complexes is more inclined to react with O 2 - to give Cu(I), accelerating the forward reaction to produce more OH. The synergistic removal of DMP and Cu(II) can be achieved after reaction. Therefore, this study provides an effective method to dispose metal ion and organic pollutant wastewater. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Goethite and Fe2+-modified goethite as ozonation catalysts for water treatment. • Fe2+-modified goethite with low defects reveals high catalytic activity. • The hydroxyl groups on goethite and Fe2+-modified goethite was active site. • Introducing Fe2+ increased the density of surface hydroxyl groups. Abstract In this study, Fe2+-modified goethite with low defects (α-Fe(Fe2+)OOH) was synthesized and characterized. Results revealed that α-Fe(Fe2+)OOH is a nano magnetic material with goethite (α-FeOOH) -type structures and has fewer Lewis acid of Fe3+ on its surface. Moreover, α-Fe(Fe2+)OOH was effective in catalytic ozonation of 4-chloronitrobenzene (4-CNB), which is a probe contaminant that cannot be efficiently removed through sole ozonation. The removal of 4-CNB increased with ozone concentration and α-Fe(Fe2+)OOH dosage, but decreased with the presence of carbonate, sulfate and phosphate. The catalytic activity of α-Fe(Fe2+)OOH also showed a dependence on solution pH. The presence of humic acid accelerated 4-CNB removal at low concentration but inhibited the removal at high concentration. In comparison with α-FeOOH, α-Fe(Fe2+)OOH significantly enhanced hydroxyl radicals generation and reduced Fe ions release in this process. The hydroxyl groups of Fe3+ on α-FeOOH and α-Fe(Fe2+)OOH surface was active site for ozone decomposition into hydroxyl radicals. Introducing Fe2+ significantly increased the density of surface hydroxyl groups relative to α-FeOOH. This enhancement significantly promoted hydroxyl radicals generation and 4-CNB degradation in the solution. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Co-incorporated α-FeOOH as a quite efficient catalyst for ozonation. • Enhancement of OH generation and oxidation/minerlization efficiency of atenolol. • 19 organic intermediates and one inorganic product of atenolol were identified. • The proposed degradation pathway of atenolol was systematically elucidated. Abstract Co-incorporated α-FeOOH nanocrystal (Co-FeOOH) was synthesized and applied for the ozonation of atenolol (ATL) in water. The compound was characterized and recognized as a transitional structure from FeOOH to CoFeO 4. The presence of Co-FeOOH was observed to support the formation of •OH by promoting ozone decomposition, and the degradation of ATL and TOC was significantly improved during the catalytic ozonation. Catalytic reactions were rationally designed in different water matrices, efficient and simultaneous removal of ATL and natural organic contaminants was achieved. It was found that the reactions kinetics depend strongly on the solution pH which could alter the surface properties of catalyst and influence the ozone-decomposition. Based on the 19 organic intermediates identified by UPLC/Q-TOF-mass spectrometry, possible reaction pathways were accordingly proposed to elucidate the mechanism of atenolol degradation by ozone molecular and •OH. Three positions of ATL structure were concluded as the most vulnerable sites to be attacked by oxygen species to initiate the degradation path. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Mn-xCe/ZSM-5 was successfully fabricated and cooperated well with VUV irradiation. • Mn-3Ce/ZSM-5 exhibited superior toluene removal efficiency (93%) in VUV-PCO process. • O 3 can be completely removed and simultaneously enhance toluene removal efficiency. • Increase of oxygen vacancies benefit adsorption and catalytic decomposition of O 3. Abstract Volatile organic compounds (VOCs) are one of the most important precursors to form the fine particulate matter and photochemical smog, and should be strictly controlled. Vacuum ultraviolet (VUV) photolysis has provided a facile and an effective way to remove VOCs due to its powerful oxidation capability under mild reaction conditions. However, VUV irradiation would generate ozone which brings about secondary pollution. In this study, ZSM-5 supported Mn-Ce mixed oxides (Mn-xCe/ZSM-5) were fabricated as efficient catalysts for ozone catalytic oxidation (OZCO) process, which were applied in combination with VUV photolysis to remove O 3 byproduct and simultaneously facilitate toluene oxidation. The results indicated that the Mn-3Ce/ZSM-5 catalyst considerably enhanced the catalytic degradation efficiency up to 93% for the gas-phase toluene, one of the hazardous VOCs. Meanwhile, almost all the O 3 by-product could be eliminated in the process. It was found that the strong interaction of the Mn O Ce bond and the variable chemical valence of Mn and Ce based species in the mixed oxides would tune the redox capacity of Mn-xCe /ZSM-5. An increase in surface Ce3+ species and surface density of oxygen vacancies would benefit the adsorption and catalytic transformation of O 3 which eventually form the reactive oxygen species over Mn-xCe/ZSM-5. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Fast and total degradation of organic dyes is possible on acid-activated bentonites. • Clay catalyst activity involves cation exchange and hydrophobic interactions. • Higher removal efficiency of cationic dyes involves strong clay-dye interactions. • Weaker degradation of anionic dyes is due to weaker contribution of adsorption. • Convenient water treatments with no contamination by metals can be envisaged. Abstract Catalytic ozonation of Methylene Blue, Methyl Green, Methyl Orange and Methyl-thymol Blue was investigated in the presence of ion-exchanged montmorillonite (NaMt and Fe(II)Mt), crude bentonite and acid-activated counterparts. An original approach never tackled so far consisted in correlating the basicity and hydrophilic character to the dye-catalyst interactions occurring on the catalyst surface. This was achieved through CO 2 and water thermal programmed desorption. Kinetics study revealed that ozonation starts in the bulk solution, and dye adsorption turns out to be an essential requirement for high catalytic effectiveness. On NaMt, dye molecules appear to adsorb mainly via hydrophobic interaction. On Fe(II)Mt, the contributions of hydrophobic interaction, cation-exchange and Fe2+ mobility to the catalytic activity prevail. Acid activated clay catalysts exhibited lowest hydrophilic character favoring adsorption through organophilic interaction and affording thorough and fast dye mineralization. This was explained in terms of increased number of silanols and –Si-O-Si- groups. For all catalysts, short ozonation of all dye molecules resulted in similar end-chain products, which were totally eliminated after prolonged reaction times. This result is of great importance because it provides valuable theoretical findings that allow envisaging total mineralization of organic molecules by recyclable metal-free clay catalysts. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Bicarbonate enhances the bromate formation by ozonation due to the role of CO 3 −. • The role played by CO 3 − in bromate formation was quantitatively evaluated. • CO 3 −-involved bromate contributes a large fraction of the total bromate formed. • The main role of CO 3 − is the oxidation of bromine to BrO in the bromate formation. • A model was developed and was shown to predicted the CO 3 − -involved bromate well. Abstract Bicarbonate scavenges OH to form CO 3 − that enhances the bromate formation by ozonation. However, the role of CO 3 − in the bromate formation during ozonation has never been quantitatively investigated. Herein, we establish a quantitative approach for evaluating the role played by CO 3 − based on the detection of CO 3 −-involved bromate and CO 3 − exposure. Experiments demonstrated that the CO 3 −-involved bromate was responsible for 33.7–69.9% of the total bromate formed with bicarbonate concentrations from 0.5 mM to 4 mM. The CO 3 − exposure was two orders of magnitude higher than the corresponding OH exposure during ozonation. These results demonstrate that CO 3 − plays a comparable or even more pronounced role in the oxidation of bromine during bromate formation than OH. A model was developed based on the ratio of bromine oxidized by CO 3 −, which could predict the CO 3 −-involved bromate formation well. Modeled and experimental results illustrated that the contribution of the CO 3 −-involved bromate to the total bromate decreased with increasing pH or initial bromide, but almost remained unchanged at different ozone dosages. Moreover, the presence of humic acid led to an increase in this contribution during ozonation. The results of this study provide a more in-depth understanding of the mechanism of bromate formation during ozonation. [ABSTRACT FROM AUTHOR]

Due to its low interfacial electron migration ability and highly hydrophilic, Fe-MCM-41 (FeM) had poor activity and stability during catalytic ozonation. To this end, the secondary metal Zn and Si-F group were introduced into the framework of FeM to create surface potential difference and hydrophobic sites. Comparative characterizations showed that there existed rich acid sites with great potential difference on F-Fe-Zn-MCM-41 (FFeZnM). Additionally, because of the existence of hydrophobic and electron-withdrawing Si-F unit, the electron migration ability, hydrophobicity and acidity of FFeZnM were enhanced. The greater O 3 mass transfer was induced by Si-F group and O 3 was directly activated at Fe and Zn Lewis acid sites into •OH, •O 2 - and 1O 2. With •OH acting as main species, FFeZnM/O 3 achieved the superior IBP removal (93.4%, 30 min) and TOC removal (46.6%, 120 min) over those of sole O 3 and F-FeM/O 3 processes, respectively. HCO 3 -, Cl-, NO 3 - and SO 4 2- hindered IBP degradation by FFeZnM/O 3 , but high concentration humic acid (HA) exhibited promotion by forming HA-IBP complex. IBP degradation by FFeZnM/O 3 was enhanced with tap water, river water, and effluent from the secondary sedimentation tank of the sewage plant acting as medium. This study proposed an innovative approach to catalyst design for catalytic ozonation. [Display omitted] • The greater IBP degradation was obtained by FFeZnM/O 3 process. • F, Fe, and Zn doping formed more acid sites & hydrophobic sites for O 3 activation. • Electron migration of O 3 on FFeZnM was enhanced. • High concentration HA promoted IBP removal by FFeZnM/O 3 process. [ABSTRACT FROM AUTHOR]

Heterogeneous catalytic ozonation is an efficient approach to remove hazardous and refractory organic contaminants in wastewater. It is crucial to design an ozone catalyst with high catalytic activity, high mass transfer and facile separation properties. Herein, easily separable aluminosilicate (Al 2 SiO 5) fibers were developed as carriers and after interface modulation, Mn-doped carbon-Al 2 SiO 5 (Mn-CAS) fibrous catalysts were proposed for catalytic ozonation. The growth of carbon shells on Al 2 SiO 5 fiber surface and the introduction of metal Mn provided abundant Lewis acid sites to catalyze ozone. The Mn-CAS fiber/O 3 system exhibited superior reactivity to degrade oxalic acid with a rate constant of 0.034 min−1, which was about 19 times as high as Al 2 SiO 5 /O 3. For coal gasification wastewater treatment, Mn-CAS fibers also demonstrated high catalytic activity and stability and the COD removal was over 56%. Computational fluid dynamic simulations proved the high mass transfer properties of fibrous catalysts. Hydroxyl radicals (•OH) were identified as the predominant active species for organic degradation. Particularly, the catalytic pathways of O 3 to •OH on Mn-O 4 sites were revealed by theoretical calculations. This work provides a novel fibrous catalyst with high reactivity and mass transfer as well as easy separation characteristics for catalytic ozonation and wastewater purification. [Display omitted] • Easily separable Mn-doped C-Al 2 SiO 5 (Mn-CAS) fibrous catalysts were proposed. • Mn-CAS fiber/O 3 system exhibited excellent wastewater treatment performance. • Compared with pellets, fibrous catalysts presented higher mass transfer properties. • Detailed evolution pathway of O 3 to •OH was revealed by theoretical calculations. [ABSTRACT FROM AUTHOR]

In this study, biochar was produced based on dehydrated excess sludge from the municipal wastewater treatment plant, which was used for catalytic ozonation of pollutants derived from landfill leachate. The necessary catalytic sites in the structure of biochar were originated from the inorganic metals and organic matters in the sludge, which included a large number of functional groups (e.g., C-C, C O, etc.), adsorbed oxygen (O ads accounted for 44.82%) and electron defects (I D /I G =1.01). These active sites could promote the generation of reactive oxygen species (ROS) (e.g., ·OH,·O2-, etc.). The synergistic interaction between the microorganisms in the activated sludge also facilitated the removal rates of pollutants. Proteobacteria, Bacteroidetes, and Deinococcu-Thermus were crucial in the bioreactor. In 16 days of reaction, the removal ratios of NH+ 4 -N and COD were 98.95 ± 0.11% and 90.89 ± 0.47%, respectively. This study not only explains the mechanism of catalytic ozonation of biochar, but also provides a new way of the practical treatment of landfill leachate. [Display omitted] ● Biochar from excess sludge was used for catalytic ozonation. ● Functional groups, O ads and electron defects of biochar make it activated. ● Biochar stimulates catalytic ozonation to produce ∙OH, ∙O2- and ∙O 2 2-. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • O 3 shows a dual role in photocatalytic ozonation process. • The introduction of O 3 overcomes the drawback of the photocatalysts. • Higher CB position benefit the activity of photocatalysts in the Vis-O 3 system. • Acid solution is beneficial for the photocatalytic ozonation. • WO 3 is also found to be active in catalytic ozonation process. Abstract Photocatalytic ozonation has great potential in wastewater treatment. However, the role of ozone and the contribution of photogenerated hole in this process have not been fully understood. Here three WO 3 materials are synthesized and used as model catalysts in visible-light photocatalytic ozonation for the mineralization of pharmaceutical pollutants. A dual role of ozone in this process has been confirmed: (i) direct oxidation of the pollutant till formation of refractory intermediates, (ii) efficient trapping of photoelectron that cannot be captured by O 2. The latter is crucial because it not only induces the O 3 −-mediated pathway for hydroxyl radical (OH) formation but also separates the hole which has proven to be capable of oxidizing water into OH. Evidenced by photoluminescence results, the intrinsic charge separation ability of WO 3 in photocatalytic ozonation is no more as important as that in photocatalysis with O 2. Finally, this process is more applicable under acidic condition. This work contributes to a better understanding of the significance of ozone in WO 3 photocatalytic ozonation and provides us an insight into the mechanism of photocatalytic ozonation. [ABSTRACT FROM AUTHOR]

The endocrine disrupting micropollutant tamoxifen can induce several effects on aquatic organisms. It is introduced into the environment mainly by wastewater treatment plant effluents. To reduce the discharge of micropollutants into surface waters, ozonation can be used as additional wastewater treatment option. For only few transformation products (TPs) formed by ozonation ecotoxicological data are available. To enable an initial estimation of ecotoxicological potentials of the TPs formed after the ozonation of tamoxifen, acute toxicity (immobilization) to Daphnia magna and green algae growth inhibition using Desmodesmus subspicatus were determined for several ozone doses spiked at pH 3 and pH 7. The initial immobilization of D. magna by tamoxifen was not further observed after ozonation. In contrast, the green algae growth inhibition increased due to ozonation of tamoxifen. Overall, five transformation products were observed. For three TPs, positive correlations of green algae growth inhibition and peak area were determined, whereas two TPs do not induce the residual effects. Based on our observations, TP 270 can be assumed as most potent of the formed TPs concerning green algae growth inhibition. Since the effect is not induced by formed N -oxides, green algae growth inhibition could be reduced by sufficient ozone exposure during wastewater treatment. [ABSTRACT FROM AUTHOR]

The study investigates the effect of catalytic ozone pretreatment via Fe 2+ and nZVI on biodegradability enhancement of complex textile effluent. The nZVI particles were synthesized and characterized by XRD, TEM and SEM analyses. Results showed that nano catalytic ozone pretreatment led to higher biodegradability index (BOD 5 /COD = BI) enhancement up to 0.61 (134.6%) along with COD, color and toxicity removal up to 73.5%, 87%, and 92% respectively. The disappearance of the corresponding GC MS & FTIR spectral peaks during catalyzed ozonation process indicated the cleavage of chromophore group and degradation of organic compounds present in the textile effluent. Subsequent aerobic biodegradation of nZVI pretreated textile effluent resulted in maximum COD and color reduction of 78% and 98.5% respectively, whereas the untreated effluent (BI = 0.26) indicated poor COD and color reduction of only 31% and 33% respectively. Bio-kinetic parameters also confirmed the increased rate of bio-oxidation at enhanced BIs. Seed germination test using seeds of Spinach ( Spinacia oleracea), indicated the effectiveness of nano catalyzed ozone pretreatment in removing toxicity from contaminated textile effluent. [ABSTRACT FROM AUTHOR]

Previously, anoxic-aerobic membrane bioreactor (MBR) coupled with mild ozonation pretreatment has been applied to remove toxic naphthenic acids (NAs) in oil sands process-affected water (OSPW). To further improve MBR performance, the optimal operation conditions including hydraulic retention time (HRT) and initial ammonia nitrogen (NH 4 + -N) need to be explored. In this study, the role of ozone pretreatment on MBR optimization was investigated. Compared with MBR treating raw OSPW, MBR treating ozonated OSPW had the same optimal operation conditions (HRT of 12 h and NH 4 + -N concentration of 25 mg/L). Nevertheless, MBR performance benefited from HRT adjustment more after ozone pretreatment. HRT adjustment resulted in NA removal in the range of 33–50% for the treatment of ozonated OSPW whereas NA removal for raw OSPW only fluctuated between 27% and 38%. Compared with the removal of classical NAs, the degradation of oxidized NAs was more sensitive to the adjustment of operation conditions. Adjusting HRT increased the removal of oxidized NAs in ozonated OSPW substantially (from 6% to 35%). It was also noticed that microbial communities in MBR treating ozonated OSPW were more responsive to the adjustment of operation conditions as indicated by the noticeable increase of Shannon index and extended genetic distances. [ABSTRACT FROM AUTHOR]

A flexible catalyst, Fe-Cu-MCM-41, was employed to enhance diclofenac (DCF) mineralization and inhibit bromate formation in catalytic ozonation process. Greater TOC removal was achieved in Fe-Cu-MCM-41/O 3 process (78%) than those in Fe-MCM-41/O 3 (65%), Cu-MCM-41/O 3 (73%) and sole ozonation (42%). But it was interesting that both Cu-MCM-41/O 3 and Fe-MCM-41/O 3 achieved 93% bromate inhibition efficiency, only 71% inhibition efficiency was observed in Fe-Cu-MCM-41/O 3 . Influence of pH, TBA/NaHSO 3 and detection of by-products were conducted to explore the mechanism. By Pyridine adsorption–IR and XPS, a relationship was found among activity of catalysts, Lewis acid sites and electron transfer effect between Fe (II/III) and Cu (I/II). Fe-Cu-MCM-41 promoted ozone decomposition to generate OH, which accounted for enhanced DCF mineralization. The consumption of aqueous O 3 also suppressed the oxidative of Br − and HBrO/Br − . More HBrO/BrO − accumulated in catalytic ozonation process and less bromate generated. Bromate formation in Fe-Cu-MCM-41/O 3 process was sensitive with pH value, the acidic condition was not favor for bromate formation. Both DCF mineralization and bromate inhibition were influenced by surface reaction. Moreover, Fe-Cu-MCM-41 showed excellent catalytic performance in suppressing the accumulation of carboxylic acid, especially for oxalic acid. Nearly no oxalic acid was detected during Fe-Cu-MCM-41/O 3 process. [ABSTRACT FROM AUTHOR]

A novel catalytic ceramic membrane (CM) for improving ozonation and filtration performance was fabricated by surface coating CuMn 2 O 4 particles on a tubular CM. The degradation of ultraviolet (UV) absorbers, reduction of toxicity, elimination of membrane fouling and catalytic mechanism were investigated. The characterization results suggested the particles were well-fixed on membrane surface. The modified membrane showed improved benzophenone-3 removal performance (from 28% to 34%), detoxification (EC 50 as 12.77%) and the stability of catalytic activity. In the degradation performance of model UV absorbers, the developed membrane significantly decreased the UV254 and DOC values in effluent. Compared with a virgin CM, this CM ozonation increased water flux as 29.9% by in-situ degrade effluent organic matters. The CuMn 2 O 4 modified membrane enhanced the ozone self-decompose to generate O 2 − and initiated the chain reaction of ozone decomposition, and subsequently reacted with molecule ozone to produce OH. Additionally, CM was able to promote the interaction between ozone and catalyst/organic chemicals to form H 2 O 2 that promoted the formation of OH. This catalytic ceramic membrane combining with ozonation showed potential applications in emerging pollutant degradation and membrane fouling elimination, and acted as a novel ternary technology for wastewater treatment and water reuse. [ABSTRACT FROM AUTHOR]

We tested the effect of soil moisture content on the efficiency of gas-phase ozonation for two types of soils containing residual petroleum. For the first soil (BM2), having a total petroleum hydrocarbons (TPH) concentration of 18,000 mg/kg soil, a moisture content of 5% benefited oxidation, giving the highest efficiency of ozonation for TPH removal and for producing soluble and biodegradable products. In contrast, higher moisture content hindered O 3 from oxidizing reactive materials in the second soil (BM3), which had a higher TPH concentration, 33,000 mg/kg soil. This trend was documented by less TPH removal, less generation of soluble and biodegradable organic products, and a carbon balance that showed retarded carbon oxidation. An unexpected phenomenon was smoldering during ozonation of air-dried (<1% moisture) BM3, which did not occur with the same moisture conditions for BM2. BM3 smoldered was due to its higher TPH content, low heat buffering, and more release of volatiles with low self-ignition points. Smoldering did not occur for ≥ 5% water content, as it suppressed the temperature increase needed to volatilize the organics that initiated smoldering. The findings underscore the importance of controlling water content during ozonation to optimize the effectiveness of ozonation and prevent smoldering. [ABSTRACT FROM AUTHOR]

A heterogeneous catalytic ozonation/membrane filtration (HCOMF) system was fabricated by integrating a flat-plate polyvinylidene fluoride (PVDF) membrane module along with a slurry catalytic ozonation reactor. The performance and catalytic activity of HCOMF was evaluated for degradation of model wastewater containing bisphenol A (BPA) and humid acid (HA) under different permeation flux in long-term continuous experiments. The membrane fouling was investigated by trans-membranous pressure (TMP), membrane filtration resistance, scanning electronic microscopy (SEM), and fluorescence spectra. The results showed that HCOMF system exhibited an excellent and stable catalytic activity in long-term continuous experiments owning to integration of 3D MnO 2 hollow microsphere ozone-catalysis with flat-plate membrane filtration. The TMP of HCOMF system didn’t increase significantly, and the membrane resistance R p and R c declined from 4% and 16% to 1% and 4%, respectively, thus, the membrane fouling of HCOMF system was mitigated compared to MF system. The mitigation of membrane fouling in HCOMF system was attributed to the increase of hydrophilicity of membrane surface and change of HA fractions. [ABSTRACT FROM AUTHOR]

Ozonation and advanced oxidation processes based on photocatalysis (P.C.) and non-thermal plasma generated in a dielectric barrier discharge (DBD) in different gas atmospheres were compared for the degradation and mineralization of 2,4-dichlorophenoxy acetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) in aqueous solutions, using a planar falling film reactor with comparable design. The energetic yields (G 50 ) as measure of the efficiencies of the different methods are for 2,4-D in the order DBD/Ar-Fenton > ozonation > DBD/Ar > P.C.ozonation > DBD/Ar:O 2 ≫ DBD/Air > P.C.oxidation. For 2,4-DCP the order is ozonation ≫ DBD/Ar-Fenton > P.C.ozonation > DBD/Ar > DBD/Ar:O 2 ≫ P.C.oxidation > DBD/Air. The degradation by using ozone is very effective, but it should be noted that the mineralization measured by the total organic carbon (TOC) removal is low. The reason is the formation of stable towards ozone intermediates, especially low chain carboxylic acids. The fate of these intermediates during the degradation with the different methods has been followed and discussed. [ABSTRACT FROM AUTHOR]

This study investigates the impact of ozonation on the concentration of two androgen steroid hormones, testosterone and androstenedione, and on androgenic activity as measured using the YAS assay. While these compounds are remarkably similar in chemical structure and showed comparable removal profiles in the presence and absence of a hydroxyl scavenger (isopropanol), large differences between percent removal of target compounds using chemical analysis and percent removal of bioactivity was observed when small ozone doses were applied. The dynamic change and initial increase in bioactivity during ozonation can be attributed to transformation products. These results demonstrate the importance of combining chemical analysis and bioanalytical techniques not only to perform a comprehensive assessment of environmental risks but also as a tool to optimize treatment technologies proposed as a mean to mitigate the impact of contaminants of emerging concern. [ABSTRACT FROM AUTHOR]

Investigations have focused on the removal and transformation of pharmaceuticals during drinking water and wastewater treatment. In the present study, we investigated for the first time the changes of the cytotoxicity and genotoxicity based on different modes of action (MoAs) during chlorination, chloramination and ozonation processes of the anti-epileptic drug carbamazepine (CBZ). The results illustrated that ozonation enhanced the cytotoxicity and the chromosome damage effects on CHO-K1 cells detected by cytokinesis-block micronucleus (CBMN) assay based on high-content screening technique, though ozonation showed the highest removal efficiency for CBZ. Non-target chemical analysis followed by quantitative structure-activity relationship (QSAR) analysis for the transformation products (TPs) suggested that the chromosomal damage effects could probably be attributed to 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM) and 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD). In contrast to CBZ itself and the ozonated sample, the chlorinated and chloraminated samples caused DNA damage effects in SOS/ umu test. Acridine, 9 (10) H-acridone, chlorinated 9 (10) H-acridone and TP-237, which were first identified in the chlorination or chloramination processes, were predicted to be the DNA damaging agents. These genotoxic TPs were primarily generated from the oxidation of seven-membered N -heterocyclic in CBZ. This study highlighted the potential adverse effects generated in ozonation process and the oxidation of N -heterocyclic containing pollutants. [ABSTRACT FROM AUTHOR]

Nanobubble and ultrasonic cavitation were applied to support and prolong oxidation reactions of ozonation. Nanobubbles increased ozone dissolution by a factor of 16 due to low buoyancy, high surface area, and stability in water. Hydroxyl radicals generated by ultrasonic cavitation produced hydrogen peroxide rather than recombining due to additional oxygen atoms supplied by the nanobubbles. The generated hydrogen peroxide formed hydroperoxyl ions that reacted with ozone to generate hydroxyl radicals. The process achieved improvements in both the loss of emitted ozone and radical recombination. Rhodamine B decomposition was used to gauge the effectiveness of the process, with the highest rhodamine B decomposition evident at a high initial pH and power and a frequency of 132 kHz as revealed in ultrasonic experiments. The process achieved more than 99% of the rhodamine B decomposition in 20 min under the most efficient conditions. The generation of hydrogen peroxide exhibited tendencies similar to those of rhodamine B decomposition, supporting the proposed mechanism. An ozonation process combined with nanobubble and ultrasonic cavitation can therefore sustain oxidizing power using continuous dissolution by nanobubbles and successive radical generation caused by hydrogen peroxide generated by cavitation. [Display omitted] • Nanobubbles reduced ozone release into the atmosphere. • Ultrasonic cavitation broke the nanobubbles and increased the gas transfer. • Ultrasonic cavitation promoted ozone consumption through hydrogen peroxide production. • Nanobubbles increase the production of hydrogen peroxide by supplying oxygen. [ABSTRACT FROM AUTHOR]

Ozonation, a viable option for improving wastewater effluent quality, requires process optimization to ensure the organic micropollutants (OMPs) elimination and disinfection under minimized byproduct formation. This study assessed and compared the efficiencies of ozonation (O 3) and ozone with hydrogen peroxide (O 3 /H 2 O 2) for 70 OMPs elimination, inactivation of three bacteria and three viruses, and formation of bromate and biodegradable organics during the bench-scale O 3 and O 3 /H 2 O 2 treatment of municipal wastewater effluent. 39 OMPs were fully eliminated, and 22 OMPs were considerably eliminated (54 ± 14%) at an ozone dosage of 0.5 gO 3 /gDOC for their high reactivity to ozone or •OH. The chemical kinetics approach accurately predicted the OMP elimination levels based on the rate constants and exposures of ozone and •OH, where the quantum chemical calculation and group contribution method successfully predicted the ozone and •OH rate constants, respectively. Microbial inactivation levels increased with increasing ozone dosage up to ∼3.1 (bacteria) and ∼2.6 (virus) log 10 reductions at 0.7 gO 3 /gDOC. O 3 /H 2 O 2 minimized bromate formation but significantly decreased bacteria/virus inactivation, whereas its impact on OMP elimination was insignificant. Ozonation produced biodegradable organics that were removed by a post-biodegradation treatment, achieving up to 24% DOM mineralization. These results can be useful for optimizing O 3 and O 3 /H 2 O 2 processes for enhanced wastewater treatment. [Display omitted] • 70 OMPs and 6 bacteria/viruses in sewage effluent were treated by O 3 and O 3 /H 2 O 2. • 33 k O3 and 23 k •OH were newly reported, calculated from QSAR and GCM. • Good prediction of OMP removals using O 3 /•OH reactivity and exposure. • The microbial inactivation was lower than the linear kinetic model prediction. • O 3 /H 2 O 2 minimized bromate formation but decreased microbial inactivation than O 3. [ABSTRACT FROM AUTHOR]

UV-filters (UVFs) are active ingredients in personal care products that protect skin from exposure to UV light. Environmentally-relevant concentrations of UVFs have recently been linked to toxicity in aquatic organisms, necessitating research into improved UVF removal in water/wastewater treatment. Here, we investigated ozonation of the three most commonly employed UVFs: octinoxate (OMC), octocrylene (OC), and oxybenzone (OXY). Specific second-order rate constants for UVF reaction with ozone were identified as follows: OMC, 5.25 × 10 4 M −1 s −1 ; OC, 1.58 M −1 s −1 ; OXY (neutral), 3.80 × 10 2 M −1 s −1 ; and, OXY (anion), 1.51 × 10 6 M ‐1 s ‐1 . These kinetic parameters indicated that OMC and OXY undergo significant (2-log or greater) transformation for typical ozone exposures in disinfection processes; however, minimal oxidation is expected for OC. UV absorbance mapping was employed to characterize the loss of UVF activity ( i.e. , absorbance across the UV-A, UV-B, and UV-C ranges) during ozonation. These 4-dimensional maps also confirmed ozone attack mechanisms, namely reaction at phenolate (OXY) and olefin (OMC, OC) groups. Primary transformation products from these reactions were identified for all three UVFs of concern. For OC and OXY, the benzophenone structure is conserved, suggesting that transformation products retain toxicity concerns. [ABSTRACT FROM AUTHOR]

Considerable interest has been given to using nanofiltration (NF) in lieu of reverse osmosis for water reclamation schemes due to lower energy consumption, higher flux rates while ensuring good micropollutants rejection. The application NF results in the generation of a large concentrated waste stream. Treatment of the concentrate is a major hurdle for the implementation of membrane technologies since the concentrate is usually unusable due to a large pollutants content. This work focuses on the application of ozonation as pretreatment of urban NF concentrates, the generation of transformation products and their relative toxicity. Three pharmaceutical micropollutants largely encountered in water cycle were selected as target molecules: acetaminophen, carbamazepine and atenolol. Through accurate-mass Q-TOF LC–MS/MS analyses, more than twenty ozonation products were detected, structure proposals and formation pathways were elaborated. Attempts were made to understand the correlation between the transformation products and acute toxicity on Vibrio fischeri strain. It is the first time that an integrated study reported on the ozonation of pharmaceuticals in urban membrane concentrates, in terms of transformation products, kinetics, degradation mechanisms, as well as toxicity assessment. [ABSTRACT FROM AUTHOR]

A novel advanced oxidation process based on the combination of ozonation with non-thermal plasma generated in a pulsed corona discharge was developed for the oxidative degradation of recalcitrant organic pollutants in water. The pulsed corona discharge in contact with liquid, operated in oxygen, produced 3.5 mg L −1 ozone, which was subsequently introduced in the ozonation reactor. The solution to be treated was continuously circulated between the plasma reactor and the ozonation reactor. The system was tested for the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and considerably improved performance as compared to ozonation alone, both with respect to the removal of the target compound and to mineralization. The apparent reaction rate constant for 2,4-D removal was 0.195 min −1 , more than two times higher than the value obtained in ozonation experiments. The mineralization reached more than 90% after 60 min treatment and the chlorine balance confirms the absence of quantifiable amounts of chlorinated by-products. The energy efficiency was considerably enhanced by shortening the duration of the discharge pulses, which opens the way for further optimization of the electrical circuit design. [ABSTRACT FROM AUTHOR]

A novel hybrid ozonation-coagulation (HOC) process was developed for application in wastewater reclamation. In this process, ozonation and coagulation occurred simultaneously within a single unit. Compared with the conventional pre-ozonation-coagulation process, the HOC process exhibited much better performance in removing dissolved organic matters. In particular, the maximal organic matters removal efficiency was obtained at the ozone dosage of 1 mgO 3 /mg DOC at each pH value (pH 5, 7 and 9). In order to interpret the mechanism of the HOC process, ozone decomposition was monitored. The results indicated that ozone decomposed much faster in the HOC process. Moreover, by using the reagent of O 3 -resistant hydroxyl radical ( OH) probe compound, para -chlorobenzoic acid (pCBA), and electron paramagnetic resonance (EPR) analysis, it was observed that the HOC process generated higher content of OH compared with pre-ozonation process. This indicates that the OH oxidation reaction as the key step can be catalyzed and enhanced by Al-based coagulants and their hydrolyzed products in this developed process. Thus, based on the catalytic effects of Al-based coagulants on ozonation, the HOC process provides a promising alternative to the conventional technology for wastewater reclamation in terms of higher efficiency. [ABSTRACT FROM AUTHOR]

Bromate (BrO 3 − ) is a possible human carcinogen regulated at a strict standard of 10 μg/L in drinking water. Various techniques to eliminate BrO 3 − usually fall into three main categories: reducing bromide (Br − ) prior to formation of BrO 3 − , minimizing BrO 3 − formation during the ozonation process, and removing BrO 3 − from post-ozonation waters. However, the first two approaches exhibit low degradation efficiency and high treatment cost. The third workaround has obvious advantages, such as high reduction efficiency, more stable performance and easier combination with UV disinfection, and has therefore been widely implemented in water treatment. Recently, advanced reduction processes (ARPs), the photocatalysis of BrO 3 − , have attracted much attention due to improved performance. To increase the feasibility of photocatalytic systems, the focus of this work concerns new technological developments, followed by a summary of reducing agents, activation methods, operational parameters, and applications. The reaction mechanisms of two typical processes involving UV/sulfite homogeneous photocatalysis and UV/titanium dioxide heterogeneous photocatalysis are further summarized. The future research needs for ARPs to reach full-scale potential in drinking water treatment are suggested accordingly. [ABSTRACT FROM AUTHOR]

Two sets of BAF – ozonation systems, with (System-A) and without (System-B) Fe 2+ dosing into BAF, were used for organic micropollutants (OMPs) and phosphorus removal in the advanced treatment of petrochemical secondary effluent. Pilot scale study showed that when the influent COD, TP and TSS were 73.0, 1.40 and 24.6 mg L −1 , the effluent COD, TP and TSS were 48.9, 0.32, 7.78 mg L −1 for System-A with the ozone and Fe 2+ dosage of 25 mg L −1 and 0.08 mmol L −1 , and 60.2, 1.16, 6.44 mg L −1 for System-B with the ozone dosage of 25 mg L −1 . The dosage of Fe 2+ into the BAF significantly enhanced the TP and OMPs removal ability. Exactly, the residual Fe 2+ in the BAF-A effluent stimulated the catalytic ozonation in the following ozone unit. Therefore, the OMPs removal in System-A was obviously better than that in System-B. The dosage of Fe 2+ from 0.02 to 0.10 mmol L −1 had slight adverse effect on the biofilm activity in BAF. Based on the TP and OMPs removal ability, the System-B is selected as a proposed process for the advanced treatment of petrochemical secondary effluent. [ABSTRACT FROM AUTHOR]

Conventional wastewater treatment has a limited capacity to reduce antibiotic resistant bacteria and genes (ARB&ARG). Tertiary treatment processes are promising solutions, although the transitory inactivation of bacteria may select ARB&ARG. This study aimed at assessing the potential of ozonation and UV 254 nm radiation to inactivate cultivable fungal and bacterial populations, and the selected genes 16S rRNA (common to all bacteria), intI1 (common in Gram-negative bacteria) and the ARG vanA , bla TEM , sul1 and qnrS . The abundance of the different microbiological parameters per volume of wastewater was reduced by ∼ 2 log units for cultivable fungi and 16S rRNA and intI1 genes, by ∼3–4 log units, for total heterotrophs, enterobacteria and enterococci, and to values close or below the limits of quantification for ARG, for both processes, after a contact time of 30 min. Yet, most of the cultivable populations, the 16S rRNA and intI1 genes as well as the ARG, except qnrS after ozonation, reached pre-treatment levels after 3 days storage, suggesting a transitory rather than permanent microbial inactivation. Noticeably, normalization per 16S rRNA gene evidenced an increase of the ARG and intI1 prevalence, mainly after UV 254 nm treatment. The results suggest that these tertiary treatments may be selecting for ARB&ARG populations. [ABSTRACT FROM AUTHOR]

The purpose of this work was to study the ozonation of nanofiltration (NF) retentates of real municipal wastewater treatment plant (MWTP) effluents for removal of microcontaminants (MCs) and toxicity. MCs present in these effluents were monitored using LC–MS/MS. Acute and chronic toxicity was addressed with Daphnia magna , Vibrio fischeri and Selenastrum capricornutum . Up to 40 MCs were found, most of them in concentrations over 100 ng/L. 90% degradation of the sum of MCs was the critical point of comparison. When the NF membrane system was applied to MWTP effluents, treatment of NF rejection needed 2.75–4.5 g O 3 /m 3 ,4.5 g O 3 /m 3 , which is less than 50% of the ozone needed for direct treatment of MWTP effluent. Treatment time (lower than 11 min) was not influenced by MCs concentration, at least in the range tested (25–190 μg/L). It has been demonstrated that consumption of ozone increased with organic load and inorganic content of different real effluents. MCs were eliminated by ozonation but acute toxicity (against V. fischeri and D. magna ) increased. Chronic toxicity results were different and contrary in D. magna and S. capricornutum , due to the generation of new transformation products more toxic to D. magna than the parent contaminants. S. capricornutum inhibition percentage decreased in all cases after ozonation treatment. According to these results, before ozonation is implemented in MWTPs for the removal of MCs, the transformation products must first be examined and the treatment time or ozone doses should be extended to complete degradation if necessary. [ABSTRACT FROM AUTHOR]

The degradation of erythromycin (ERY) and ethylparaben (EtP) in urban wastewater effluents at low concentration level during ozonation was investigated under different experimental conditions. Both substrates were rapidly eliminated within 2 min at low ozone dose of 0.3 mg L −1 and the experimental data were well fitted in the pseudo-first-order kinetic model. The ratio of HO - and O 3 -exposure ( R ct ) at the inherent pH was found to be 1.9 × 10 −8 . The degradation of ERY and EtP was pronounced at pH 8 compared to acidic pH conditions, while the degradation rate of both substrates was found to be matrix-depended. It was also shown that both O 3 - and HO -mediated pathways are involved in the degradation of EtP, whereas the saturated-rich structure of ERY renders it O 3 -recalcitrant. Under the optimum O 3 dose, the BrO 3 − concentration was found to be lower than 10 μg L −1 . Five and fifteen transformation products were elucidated during ERY and EtP oxidation, respectively. The root and shoot inhibition can be attributed to the oxidation products formed upon dissolved effluent organic matter transformation. Escherichia coli harbouring resistance to ERY survived ozonation better than EtP-resistant E. coli . However, neither ERY- nor EtP-resistant E. coli were detected after 15 min of ozonation. [ABSTRACT FROM AUTHOR]

Ozonation of a commonly used non-steroidal anti-inflammatory drug indomethacin (IM) was studied. Kinetic constants of IM with ozone and hydroxyl radicals were measured at an order of magnitude of 10 5 M −1 s −1 and 10 9 M −1 s −1 , respectively. IM was degraded within 7 min under the lowest ozone dose, but TOC removal was only 50% even under the highest ozone dose used in the experiments. Ozone rather than hydroxyl radicals was found to be the main oxidant during reaction, with a contribution rate of 80% under pH 7. Six intermediates were identified by high resolution mass spectrometer. Nitrogen atom, C C double bond and benzene ring were found to be the main reaction sites. Electrophilic attack or Criegee cyclo-addition were proved to be the most probable pathways at the first step. The formation mechanism of one of the ozone products was first proposed during the experiment, then confirmed by the density functional theory (DFT) calculation. Acetic acid, formic acid and oxalic acid were detected as small molecule organic products. The toxicity change during ozonation was measured by luminescent bacterium with results showing that the toxicity can be reduced to zero when ozone dose was high enough. [ABSTRACT FROM AUTHOR]

Worldwide water shortage increase and water quality depletion from microbial and chemical compounds, pose significant challenges for today’s water treatment industry. Both the development of new advanced oxidation technologies, but also the enhancement of existing conventional technologies is of high interest. This study tested improvements to conventional ozonation that reduce the formation of the oxidation-by-product bromate, while maintaining the effectiveness for removal emerging contaminants (atrazine). MnO 4 − , ClO 2 − , ClO 2 , ClO − , CH 3 COOO − , HSO 5 − or S 2 O 8 −2 with NH 4 + were tested as pre-treatments to ozonation of ground water. Each oxidant and NH 4 + were added in a single stage or separately prior to ozonation. To the best of our knowledge, this is the first study that has tested all the above-mentioned oxidants for the same water matrix. Based on our results, the most promising pre-treatments were MnO 4 − − NH 4 + , ClO 2 − − NH 4 + and ClO 2 − NH 4 + . MnO 4 − − NH 4 + was the only pre-treatment that did not inhibit atrazine removal. When compared with the previously proposed Cl 2 /NH 4 + pre-treatment, MnO 4 − + NH 4 + was found as effective for preventing BrO 3 − formation, while atrazine removal was higher. In addition, MnO 4 − + NH 4 + can be added in a single stage (compared to the 2 stage addition of Cl 2 /NH 4 + ) without causing the formation of potentially harmful chlorination-by-products. [ABSTRACT FROM AUTHOR]