Ozone Dose Research Articles

In Vitro Investigation of the Antimicrobial Potential and Cell Viability of Different Dosages of Ozone Therapy

ABSTRACT The aim of the study was to evaluate and compare, in vitro, the cytotoxicity of different applied ozone dosages in keratinocyte (NOK) and fibroblast (L929) cell lines, as well as the antimicrobial potential for Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). NOK and L929 cells and strains of gram-positive bacteria S. aureus and gram-negative bacteria E. coli were divided into seven experimental groups: ozone at doses from 0, 0.005, 0.01, 0.02, 0.03, 0.04 and 0.05 mg/L. The effect of ozone on cell viability/cytotoxicity was determined using the alamarBlue® assay, the Live/Dead® assay and the morphometric analysis of the percentage of live and dead cells. The results show that applied ozone dosages of 0.005, 0.01 and 0.02 mg/L showed the highest viability values of NOK and L929 cells, as well as a higher density and percentage of live cells in the 72-hour experimental. However, no difference was observed in the percentage of dead cells between the experimental groups. Furthermore, ozone promoted a reduction in CFUs at all tested dosages. With the results obtained in the present study, it is possible to confirm the restorative potential of ozone therapy in a dose-dependent response, as well as its antimicrobial potential.

Enhanced ozonation of vanillin catalyzed by highly efficient magnetic MnFe2O4/ZIF-67 catalysts: Synergistic effects and mechanism insights.

In this study, we synthesized magnetic MnFe2O4/ZIF-67 composite catalysts using a straightforward method, yielding catalysts that exhibited outstanding performance in catalyzing the ozonation of vanillin. This exceptional catalytic efficiency arose from the synergistic interplay between MnFe2O4 and ZIF-67. Comprehensive characterization via x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FE-SEM), and energy dispersive spectroscopy (EDS) confirmed that the incorporation of MnFe2O4 promoted the creation of oxygen vacancies, resulting in an increased presence of l adsorbed oxygen (Oads) and the generation of additional ·OH groups on the catalyst surface. Utilizing ZIF-67 as the carrier markedly enhanced the specific surface area of the catalyst, augmenting the exposure of active sites, thus improving the degradation efficiency and reducing the energy consumption. The effects of different experimental parameters (catalyst type, initial vanillin concentration, ozone dosage, initial pH value, and catalyst dosage) were also investigated, and the optimal experimental parameters (300 mg/L1.0-MnFe2O4/ZIF-67, vanillin concentration = 250 mg/L, O3 concentration = 12 mg/min, pH = 7) were obtained. The vanillin removal efficiency of MnFe2O4/ZIF-67 was increased from 74.95% to 99.54% after 30 min of reaction, and the magnetic separation of MnFe2O4/ZIF-67 was easy to be recycled and stable, and the vanillin removal efficiency of MnFe2O4/ZIF-67 was only decreased by about 8.92% after 5 cycles. Additionally, we delved into the synergistic effects and catalytic mechanism of the catalysts through kinetic fitting, reactive oxygen quenching experiments, and electron transfer analysis. This multifaceted approach provides a comprehensive understanding of the enhanced ozonation process catalyzed by MnFe2O4/ZIF-67 composite catalysts, shedding light on their potential applications in advanced oxidation processes. PRACTITIONER POINTS: A stable and recyclable magnetic composite MnFe2O4/ZIF-67 catalyst was synthesized through a simple method. The synergistic effect and catalytic mechanism of the MnFe2O4/ZIF-67 catalyst were comprehensively analyzed and discussed. A kinetic model for the catalytic ozone oxidation of vanillin was introduced, providing valuable insights into the reaction dynamics.

Case study on water quality index for wastewater treatment in Mumbai

Abstract The traditional wastewater treatment process is laborious and demanding in terms of time, energy, and space. With rapid advancements, there's a quest for more efficient techniques that can achieve comparable treatment outcomes while minimizing these demands. This study proposes a solution by employing ozone as an Advanced Oxidation Process (AOP) to expedite the treatment while enhancing the water quality. The Water Quality Index (WQI) offers a consolidated representation of overall water quality by considering multiple quality parameters. Although typically used for assessing surface water quality, this study utilizes WQI to gauge the enhancement in parameters post-treatment. The research investigates the impact of varied ozone doses on raw sewage samples collected from four different sites in Mumbai, focusing on parameters such as dissolved oxygen, turbidity, hardness, chemical oxygen demand (COD), and WQI. The results demonstrate a notable percentage enhancement in WQI, ranging from 30 to 60% across various sites within a short 25-minute timeframe, attributed to the application of ozone.

Virus inactivation in low ozone exposure water reuse applications

In drinking water applications, an ozone exposure (Ct) based framework has been historically used to validate ozone disinfection. However, significant viral inactivation can be achieved with little to no measurable ozone exposure. Additionally, ozone exposure depends on multiple water quality variables as well as the calculation/ozone measurement method used. In this study, we evaluated alternative ozone monitoring frameworks as well as the impact of water quality variables on ozone decay kinetics and virus/coliform inactivation. Here we show that both change in UV254 absorbance and applied O3:TOC were well correlated with viral inactivation and these frameworks were resilient to changes in water quality. Both increasing temperature (12–30 ⁰C) and pH (5.5–8.4) was shown to significantly increase the ozone decay rate and decreased the resulting ozone exposure by as much as ∼90% in the case of pH. However, due to the increased reaction rate of ozone with viruses at elevated temperature and pH, there was only a minor impact (∼20% in the case of pH) in overall disinfection performance for a given O3:TOC. These frameworks were also considered for variable source water with TOC (5–11 mg/L) and TSS (1.2–5.8 mg/L). Change in UV254 absorbance or applied ozone dose (mg/L) were the strongest indicators of disinfection performance for source waters of variable TOC, however site-specific testing may be needed to apply this framework. Challenge testing with influent nitrite indicated that ozone disinfection performance is significantly impacted (>50% reduction in inactivation) in the presence of nitrite thus enforcing the importance of accounting for this value in the applied ozone dose. Multi-point ozone dissolution was investigated as an alternative ozone application method that may present a benefit with respect to overall disinfection performance especially if nitrite was present. Developing and validating these alternative monitoring frameworks and ozone application methods is imperative in water reuse applications where unnecessary elevated ozone exposure may lead to harmful byproduct formation.

Increased Beneficial Outcome of Insulin by Medical Ozone against Experimentally Diabetic Rats

The present research aimed to determine the effective dose of medical ozone on some blood parameters in experimental diabetic rats.48 adult female rats with (a 180 - 200 g) weight average were randomly divided into (6) groups (n=8): control (T1), Medical ozone (MO) (T2), diabetic (T3), ozone-treated diabetic (T4), insulin-treated diabetic(T5), and MO, insulin-treated diabetic (T6). Diabetes was induced by an intraperitoneal injection of a single dose of Alloxan (150 mg/kg of the body weight). The diabetic rats were left for 2 days to assure the stability of diabetes in them, before continuing experiments. The results of RBCs in groups (T2, T4, T5, and T6) showed a significant increase compared with the diabetic group and control group, and Hb and WBCs parameters showed a significant decrease in (T3, T4, and T5)When compared with other groups. The results of the platelet count there was a significant increase in (T3, T4, and T5) compared to the control group. Clotting time and calcium ions recorded a significant decrease in all treated diabetic groups (T3, T4, T5, and T6) when compared with (T1 and T2), at the same time, the results of bleeding time recorded a significant decrease in (T3 and T4 ) compared with the other groups while (T4 and T5) showed non-significant difference compared to (T1 and T2). The current study concluded that the treatment combination of medical ozone and insulin has ameliorative effects on some blood parameters except clotting time and calcium, ions.

Novel cow dung-doped sludge biochar as an efficient ozone catalyst: Synergy between graphitic structure and defects induces free radical pathways

A composite material, cow dung-doped sludge biochar (Zn@SBC-CD), was synthesized by one-step pyrolysis using ZnCl2 as an activating agent and applied to a catalytic ozonation process (COP) for methylene blue (MB) removal. SEM, XRD, FTIR, XPS and BET analyses were performed to characterize the biochar (BC) catalysts. Zn@SBC-CD had high graphitization degree, abundant active sites and uniform distribution of Zn on its surface. Complete removal of MB was achieved within 10 min, with a removal rate much higher than that of ozone alone (32.4%), implying the excellent ozone activation performance of Zn@SBC-CD. The influence of experimental parameters on MB removal efficiency was examined. Under the optimum conditions in terms of ozone dose 0.04 mg/mL, catalyst dose 400 mg/L and pH 6.0, COD was completely removed after 20 min. Electron paramagnetic resonance (EPR) analysis revealed radical and non-radical pathways were involved in MB degradation. The Zn@SBC-CD/O3 system generated superoxide anion radicals (•O2−), which were the main active species for MB removal, through adsorption, transformation, and transfer, Furthermore, Zn@SBC-CD exhibited good reusability and stability in cycling experiments. This study provides a novel approach for the utilization of cow dung and sludge in synthesis of functional biocatalysts and application in organic wastewater treatment.

Ozone Treatment as an Approach to Induce Specialized Compounds in Melissa officinalis Plants.

Plants are constantly subjected to environmental changes that deeply affect their metabolism, leading to the inhibition or synthesis of "specialized" compounds, small organic molecules that play a fundamental role in adaptative responses. In this work, Melissa officinalis L. (an aromatic plant broadly cultivated due to the large amounts of secondary metabolites) plants were exposed to realistic ozone (O3) dosages (80 ppb, 5 h day-1) for 35 consecutive days with the aim to evaluate its potential use as elicitor of specialized metabolite production. Ozone induced stomatal dysfunction throughout the whole experiment, associated with a low photosynthetic performance, a decrease in the potential energy conversion activity of PSII, and an alteration in the total chlorophyll content (-35, -36, -10, and -17% as average compared to the controls, respectively). The production of hydrogen peroxide at 7 days from the beginning of exposure (+47%) resulted in lipid peroxidation and visible injuries. This result suggests metabolic disturbance within the cell and a concomitant alteration in cell homeostasis, probably due to a limited activation of antioxidative mechanisms. Moderate accumulated doses of O3 triggered the accumulation of hydroxycinnamic acids and the up-regulation of the genes encoding enzymes involved in rosmarinic acid, phenylpropanoid, and flavonoid biosynthesis. While high accumulated doses of O3 significantly enhanced the content of hydroxybenzoic acid and flavanone glycosides. Our study shows that the application of O3 at the investigated concentration for a limited period (such as two/three weeks) may become a useful tool to stimulate bioactive compounds production in M. officinalis.

Towards zero excess sludge discharge with built-in ozonation for wastewater biological treatment

In this study, a biological treatment process, which used a built-in ozonation bypass to achieve sludge reduction, was built to treat the industrial antifreeze production wastewater (mainly composed of ethylene glycol). The results indicated there is a positive correlation between ozone dosage and sludge reduction. At the laboratory level, the MLSS in the system can be stably controlled at around 3400 mg MLSS L−1 under the dosage of 0.18 g O3 g−1 MLSS. Ozonation can increase the compactness of sludge flocs (fractal dimension increased from 1.89 to 1.92). Ozone destroys microbial cell membranes and alters the structure of sludge flocs through direct oxidation through electrophilic reactions. It leads to the release of intracellular polysaccharides, proteins, and other biological macromolecules in microorganisms, thereby promoting the implicit growth of microbial populations. Some bacteria such as g_Pseudomonas, g_Gemmobacter, etc. have strong ethylene glycol degradation ability and tolerance to ozonation. The removal of ethylene glycol includes the glyoxylate cycle, glycine serine carbon cycle, and the glutamate-cysteine ligase pathway of assimilation. Gene KatG and gpx may be key factors in improving microbial tolerance to ozonation. The comprehensive evaluation from the perspectives of cost and carbon emission shows that choosing ozone cracking-implicit growth in wastewater treatment systems has significant cost advantages and application value.

Excessive Ozonation Stress Triggers Severe Membrane Biofilm Accumulation and Fouling.

The established benefits of ozone on microbial pathogen inactivation, natural organic matter degradation, and inorganic/organic contaminant oxidation have favored its application in drinking water treatment. However, viable bacteria are still present after the ozonation of raw water, bringing a potential risk to membrane filtration systems in terms of biofilm accumulation and fouling. In this study, we shed light on the role of the specific ozone dose (0.5 mg-O3/mg-C) in biofilm accumulation during long-term membrane ultrafiltration. Results demonstrated that ozonation transformed the molecular structure of influent dissolved organic matter (DOM), producing fractions that were highly bioavailable at a specific ozone dose of 0.5, which was inferred to be a turning point. With the increase of the specific ozone dose, the biofilm microbial consortium was substantially shifted, demonstrating a decrease in richness and diversity. Unexpectedly, the opportunistic pathogen Legionella was stimulated and occurred in approximately 40% relative abundance at the higher specific ozone dose of 1. Accordingly, the membrane filtration system with a specific ozone dose of 0.5 presented a lower biofilm thickness, a weaker fluorescence intensity, smaller concentrations of polysaccharides and proteins, and a lower Raman activity, leading to a lower hydraulic resistance, compared to that with a specific ozone dose of 1. Our findings highlight the interaction mechanism between molecular-level DOM composition, biofilm microbial consortium, and membrane filtration performance, which provides an in-depth understanding of the impact of ozonation on biofilm accumulation.

Ozone Therapy on Fungi that Cause Onychomycosis

ABSTRACT Onychomycosis is a common fungal infection of the nails, predominantly caused by dermatophytes and is a notoriously difficult condition to treat. Thus, the objective of the present study was to evaluate and compare, in vitro, the efficacy of different applied ozone dosages against the main fungi that cause onychomycosis. Dermatophyte fungi Trichophyton rubrum (ATCC 28,188) and Microsporum gypseum (ATCC 24,102) were incubated at 28 °C for 14 days. Treatments were divided into nine experimental groups according to applied ozone dosages: Control Group 0 mg/m2: fungi were cultured but received no treatment; cultured fungi that received ozone therapy for 157, 314, 471, 628, 785 943, 1100 and 1257 mg/m2. The main results indicate that topical ozone therapy effectively reduced the germination percentage of T. rubrum and M. gypseum in all experimental periods, achieving a complete eradication with a treatment time of 628 and 1257 mg/m2, respectively. In conclusion, ozone therapy used topically with an applied ozone dosage of 628 mg/m2 for T. rubrum and 1257 mg/m2 for M. gypseum promoted antifungal action on the main dermatophytes responsible for critical complications of onychomycosis. Therefore, ozone therapy can be proposed as an adjuvant for dermatological treatments

Emerging contaminants and pathogenic microorganisms elimination in secondary effluent by graphitic carbon nitride photocatalytic ozonation processes

The complexity of water contaminants, both chemical and biological requires an efficient and feasible treatment alternative. Herein, the photocatalytic ozonation treatment using graphitic carbon nitride catalysts was effectively applied for the elimination of a mixture of targeted chemical contaminants, and both Escherichia coli bacteria and Human polyomavirus JC (JC virus) in real secondary wastewater. The exfoliation treatment was compared in catalysts prepared using urea and melamine as precursors. The physical treatment provided no significant enhancement in the urea-based catalyst, while the improvement in the structure of the melamine-based (36MCN) material and formation of melem heterojunction increased its catalytic properties. In both sets of contaminants, the photocatalytic ozonation systems were superior to photolytic ozonation, especially regarding ozone consumption. The best catalyst, 36MCN, resulted in a decrease of 57.5%, 33.0% and 29.0% in the ozone dose required to eliminate chemical, bacteria and virus contaminants, respectively. The hydroxyl radicals were also shown as a key responsible for the pollutant’s elimination. The higher radical production and decomposition of ozone are possible indications of the better performance of graphitic carbon nitride photocatalytic ozonation, as an efficient tertiary wastewater alternative.

Assessment of an hybrid process coupling ozonation and anodic oxidation in a monophasic configuration

This prospective study assessed a hybrid process that combines ozonation with anodic oxidation (AO/O3) with two boron-doped diamond (BDD) electrodes to treat a model aqueous solution containing 30 ppm of alachlor at pH 5 in a phosphate buffer. An innovative monophasic configuration, operated batch-wise, in which an ozone-stock solution was injected at t0 in the electrochemical reactor, was proposed in order to avoid introduction of ozone-enriched gas bubbles. The alachlor parent molecule was almost entirely degraded within around 150 min of reaction time by anodic oxidation alone, whatever the applied current intensity (200, 500 and 800 mA). The mineralization efficiency varied from 50 % at 200 mA to 80 % at 800 mA after 120 min. The results emphasized that the anodic oxidation was a diffusion-controlled process. Addition of ozone at a low ozone dose of 1.9–2.3 mol of ozone per mol of alachlor allowed to decrease the ozone half-life time 2.7 times with the hybrid process compared to ozonation alone. This faster ozone consumption was concomitant with an enhanced alachlor degradation rate, with a corresponding half-life time around two-times lower. However, owing to the low ozone dose applied and the short ozone lifetime in solution (around 25–30 min), similar mineralization efficiencies were noticed for both AO/O3 and AO processes. Thus, the application of pulse ozone-stock solution re-injections every 20 min to prolong the ozone exposure was assessed to overcome this limitation. However, the effect on the mineralization rate remained small, even if it allows to enhance even more the alachlor parent molecule degradation rate. The low influence of the hybrid process on the mineralization rate was attributed to the production of aliphatic fatty acids by-products that are poorly reactive with hydroxyl radicals, and whose the degradation by AO is the rate limiting step.

Performance evaluation and optimization of a suspension-type reactor for use in heterogeneous catalytic ozonation

Packed fixed-bed reactors are traditionally used for heterogeneous catalytic ozonation. However, a high solid-to-liquid requirement, poor ozone dissolution, ineffective utilization of catalyst surface area, and production of large amounts of catalyst waste impede application of such reactors. In this study, we designed a suspension catalytic ozonation reactor and compared the performance of this reactor with that of a traditional fixed-bed catalytic ozonation reactor employing oxalic acid (OA) as the target contaminant. Our results showed that total O3 dissolved into the suspension reactor (117–134 mg.L−1) was much higher compared to that measured in the fixed-bed reactor (53 mg.L−1) due to a higher O3(g) interphase mass transfer rate in the suspension reactor. In accordance with the higher O3(g) interphase mass transfer, we observed a much higher proportional OA removal (32 %) compared to that achieved in the fixed-bed reactor (10%) employing an Fe-oxide catalyst supported on Al2O3 (Fe-oxide@Al2O3) in both reactors. Use of a double-layered Cu-Al hydroxide (Cu-Al LDHs) catalyst in the suspension reactor further enhanced the performance with nearly 90 % OA removal observed. Given the superior performance of the suspension reactor, we investigated the impact of operating conditions (catalyst dosage, hydraulic retention time and ozone dosage) employing Cu-Al LDHs as the catalyst. We also developed a mathematical kinetic model to describe the performance of the suspension reactor and, through use of the kinetic model, showed that O3(g) interphase transfer rate was the rate-limiting step in OA removal. Thus, improvement in ozone gas diffuser design is required to improve the performance of the suspension reactor. Overall, the present study demonstrated that suspension reactors were more effective than fixed-bed reactors for oxidation of surface-active organic compounds such as OA due to the higher ozone interphase mass transfer rate and effective utilization of the catalyst surface area that can be achieved. As such, further research on suspension reactor design and development of catalysts suitable for use in suspension reactors should facilitate large-scale application of catalytic ozonation processes by the wastewater treatment industry.

Homogeneous oxidation of EE2 by ozone: Influencing factors, degradation pathway, and toxicity assessment

17α-Ethinylestradiol(EE2) is a common hormone drug that plays an essential role in endocrine and reproductive health. However, estrogens are degraded only to a limited extent by humans and livestock themselves, and most of them are excreted in undegraded or partially degraded form from human and livestock feces and urine into water bodies, posing a austere ecological risk. Of the known degradation processes in wastewater treatment plants, ozone-induced advanced oxidation shows tremendous potential. At the same time, the limitations of the test methodology makes it extremely difficult to do an in-depth investigation of the degradation mechanism. In this study, the influencing factors, including ozone dose, initial concentration, and pH were investigated. The degradation pathways of EE2 were analyzed by combing with quantum chemical calculations and high performance liquid chromatography coupled with quadrupole-time of flight tandem mass spectrometry (HPLC-Q-TOF-MS). Toxicity Estimation Software Tool (T.E.S.T) evaluated EE2 and its degradation intermediates for a variety of toxicities. And the results showed that reactions such as oxidative hydroxylation of the benzene ring and oxidative ring opening of the aliphatic ring mainly occurred during the degradation of estrogens, and the reaction was initially fast. The degradation effect is lower under neutral conditions, and the acidity and alkalinity of the solution are reduced with the reaction process under strong acid and alkaline conditions. The products of the experimental reactions reflect the active site, e.g., product P1 reflects C(5) as the site of easy reaction, which is consistent with previous theoretical predictions, suggesting that theoretical studies can provide complementary information on oxidation. The toxicity of intermediates obtained from partial ozone degradation improved compared to EE2, and the mutagenicity of EE2 was elevated greatly. However, single ozonation significantly diminished the developmental toxicity and bioaccumulation factor for a large proportion of intermediates. This work may contribute to the theoretical foundation for the practical application of ozone oxidation of environmental estrogens.

Efficiency of ozonation and sulfate radical - AOP for removal of pharmaceuticals, corrosion inhibitors, x-ray contrast media and perfluorinated compounds from reverse osmosis concentrates

This study investigated the elimination of pharmaceuticals, corrosion inhibitors, x-ray contrast media and perfluorinated compounds from reverse osmosis concentrates during ozonation and UV/persulfate processes. Second-order rate constants for the reactions of candesartan, irbesartan, methyl-benzotriazole, and chloro‑benzotriazole with sulfate radical (SO4·−) were determined for the first time. Experiments were conducted in buffered pure water, in buffered water added with the matrix substituents chloride, carbonate, NOM, and reverse osmosis concentrate with spiked micropollutants (MP). UV/persulfate eliminated all MP to a higher extent than ozonation in RO concentrates due to the higher yield of oxidative species and photolytic degradation. Compounds with electron-rich moieties such as carbamazepine, diclofenac, metoprolol, and sulfamethoxazole were completely eliminated with small ozone doses (< 0.5 mg O3 / mg DOC) and with a small fluence (< 5000 J m−2) in UV/persulfate processes. Photosensitive compounds with high reactivity towards hydroxyl radicals (·OH) and SO4·− like the x-ray contrast media Iopamidol, Iohexol, and Amidotrizoic acid were successfully eliminated with a reasonable fluence in UV/persulfate, whereas these compounds persist in ozonation at common ozone dosages. However, much higher fluences and ozone dosages were required for the least reactive compounds like the class of benzotriazoles. Comparing the application of both oxidative processes to the RO concentrate, ozonation has the disadvantage of forming bromate. The energy input of both processes strongly depends on the target compounds to be eliminated. For the elimination of compounds such as sulfamethoxazole, ozonation is a feasible technique, whereas UV/persulfate is better suited for the elimination of recalcitrant compounds such as x-ray contrast media. In general, oxidative process treatment of RO concentrate could be applied to partly abate micropollutants before discharge.

Advanced treatment of landfill leachate by catalytic ozonation with MnCeOx/γ-Al2O3 catalyst

Ozonation combined with an efficient and stable catalyst has been demonstrated to be a feasible solution in for removing refractory contaminants from landfill leachate. In this study, MnCeOx/γ-Al2O3 catalyst fabricated with impregnation method was adopted as ozone catalyst for advanced treatment of landfill leachate biochemical effluent (LLBE). The optimized Mn80Ce20Ox/γ-Al2O3 catalyst was fabricated with Mn/Ce molar ratio of 4:1, a metal oxide loading amount of 3.1 wt%, and calcination temperature of 500 °C. By treating LLBE, the removal of chemical oxygen demand (COD) and UV254 in 120 min reached 82.4 % and 96.3 %, respectively, with ozone dose of 15.3 mg L−1, catalyst dosage of 250 g L−1, and the initial pH of 5. The Mn80Ce20Ox/γ-Al2O3 catalyzed ozonation process conformed to pseudo-first-order kinetics with degradation rate constants of 0.0171 min−1 and 0.0313 min−1 for COD and UV254, respectively, which were 3.4 and 2.8 times higher than those of ozonation alone. The MnCeOx/γ-Al2O3 also showed satisfactory catalytic activity and stability based on eight times catalytic ozonation treatments on LLBE.

Phytotoxic Ozone Dose-Response Relationships for Durum Wheat (Triticum durum, Desf.).

Ozone (O3) pollution poses a significant threat to global crop productivity, particularly for wheat, one of the most important staple foods. While bread wheat (Triticum aestivum) is unequivocally considered highly sensitive to O3, durum wheat (Triticum durum) was often found to be more tolerant. This study investigated the O3 dose-response relationships for durum wheat in the Mediterranean region, focusing mainly on grain yield losses, and utilizing the phytotoxic ozone dose (POD) metric to describe the intensity of the stressor. The results from two experiments with Open-Top Chambers performed in 2013 and 2014 on two relatively sensitive durum wheat cultivars confirmed that this wheat species is far more tolerant than bread wheat. The use of a local parameterization of a stomatal conductance model based on field measurements did not significantly improve the dose-response relationships obtained in comparison to the generic parameterization suggested by the Mapping Manual of the United Nations Economic Commission for Europe (UNECE). The POD6 critical level of 5 mmolO3 m-2 for 5% grain yield loss was remarkably higher than the one established for bread wheat with analogous experiments, highlighting that O3 risk assessments based on bread wheat may largely overestimate the damage in the Mediterranean region where durum wheat cultivation prevails.

Ozone and Laser Effects on Dentin Hypersensitivity Treatment: A Randomized Clinical Study

IntroductionThe aim of this study was to evaluate and compare the clinical efficacy of diode laser and ozone gas in the treatment of dentin hypersensitivity (DHS). MethodsOne hundred thirty-two teeth from 44 patients with moderate DHS were randomized into 3 groups according to a split-mouth design. In the diode laser group, the operator irradiated the superficial dentin exposed with an 808-nm wavelength and incremental power from 0.2 to 0.6 W with a 20-second interval. In the ozone gas group, the operator applied a high dose of ozone (32 g/m3) for 30 seconds using a silicon cup. In the placebo group, no therapy was applied. The dentin sensitivity level was evaluated upon enrollment (T0), immediately after treatment (T1), 3 months post-treatment (T2), and 6 months post-treatment (T3) with a cold air blast challenge and tactile stimuli. The pain severity was quantified according to the visual analogue scale. The Wilcoxon signed rank test was used to scrutinize potential statistical disparities among the treatments. Statistical significance was predetermined at P < .05. ResultsA significant decrease of DHS was observed in the ozone gas group and the `diode laser group immediately after treatment and after 3 and 6 months of the therapy. After 6 months from the therapy, the sensitivity values in the teeth treated with ozone gas remained statistically lower than those treated with diode lasers (P < .05). ConclusionsA laser diode and ozone gas are both efficient as dentin sensitivity treatment. Ozone maintains an invariable effectiveness after 6 months.

Is catalytic ozonation always an efficient treatment for refractory pollutant in various water matrices?

In this study, surrogate indicators (·OH yield and Rct value) were developed to identify whether homogeneous and heterogeneous catalysts should be added during ozonation of refractory pollutants. The abatement of atrazine (ATZ) was in the order of O3/H2O2 process (94 %) > O3/γ-Al2O3 process (70 %) > ozonation alone process (55 %) in synthetic water samples at pH 7, which was in agreement with the order of ·OH yield and Rct value. However, the abatement of ATZ during ozonation alone process (0.64–0.62) was higher than O3/H2O2 process (0.63–0.60) and O3/γ-Al2O3 process (0.48–0.49) in the presence of high dosage of humic acid (HA, 3.38 × 10−1–4.50 × 10−1 mg C/L) at pH 7. The abatement of ATZ was linearly proportional to ·OH yield, whereas it was not linearly proportional to Rct value in the synthetic water samples containing HA at pH7. The abatement of ATZ during ozonation alone process was higher than that during catalytic ozonation process by one-time ozone dosing method in real water. The abatement of ATZ during O3/H2O2 process and O3/γ-Al2O3 process were higher than that during ozonation alone process by three-time ozone dosing method in real water, which was linearly proportional to ·OH yield and Rct value. The residual DOM in phase III become recalcitrant to ozone, which could be decomposed by catalyst forming ·OH. Overall, this result implies that the comparison of ·OH yield and Rct value between ozone decay by DOM in various water matrices and by catalyst should be concerned before the addition of catalyst during ozonation process was applied in real water.

Removal characteristics of 53 micropollutants during ozonation, chlorination, and UV/H2O2 processes used in drinking water treatment plant

The removal of 53 emerging micropollutants (MPs), including 10 per- and polyfluorinated substances (PFASs), 25 pharmaceuticals and personal care products (PPCPs), 7 pesticides, 5 endocrine disrupters (EDCs), 3 nitrosamines, and 3 taste and odor compounds (T&Os), by chlorination, ozonation, and UV/H2O2 treatment was examined in deionized water and surface waters used as the raw waters in drinking water treatment plants (DWTPs) in South Korea. The UV/H2O2 treatment was effective in the removal of most MPs, whereas chlorination was selectively effective for 19 MPs, including EDCs (>70 %). MPs containing aromatic ring with electron-donating functional group, or primary and secondary amines were effectively removed by chlorination immediately upon reaction initiation. The removal of MPs by ozonation was generally lower than that of the other two processes at a low ozone dose (1 mg L−1), but higher than chlorination at a high ozone dose (3 mg L−1), particularly for 16 MPs, including T&Os. Compared in deionized water, the removals of MPs in the raw water samples were lower in all three processes. The regression models predicting the rate constants (kobs) of 53 MPs showed good agreement between modeled and measured value for UV/H2O2 treatment (R2 = 0.948) and chlorination (R2 = 0.973), despite using only dissolved organic carbon (DOC) and oxidant concentration as variables, whereas the ozonation model showed a variation (R2 = 0.943). Our results can provide the resources for determining which oxidative process is suitable for treating specific MPs present in the raw waters of DWTPs.