Ozone Dose Research Articles

Treatability of BPA Containing Wastewater by Catalytic and Photocatalytic Ozone Processes Using n.TiO2

In this study, the treatment of synthetic wastewater containing 10 mg/L Bisphenol A (BPA) has been investigated by the catalytic and photocatalytic ozonation process. n.TiO2 nanocatalysts have been used in catalytic (COP) and photocatalytic (PCOP) ozonation processes. Optimum parameters have been determined as pH 6.32, 1200 mg/L ozone dose, 50 mg/L n.TiO2 catalyst dose and 12.5 min reaction time for COP. Optimum parameters have been found as pH 6.32, 1200 mg/L ozone dose, 50 mg/L n.TiO2 catalyst dose, 18 Watt UV light intensity, and 10 min reaction time for PCOP. The removal efficiencies of BPA have been obtained as 95.51% and 98.09% for COP and PCOP, respectively. Kinetic analyses showed that BPA removal has been carried out Pseudo second order kinetics with R2 values of 99.1 for both processes.

Catalytic ozonation using spent battery-based (SB) catalysts for dyes, micropollutant removal and disinfection

This study aimed to explore the use of three different Spent battery-based (SB) catalysts of ozonation to remove organic contaminants and disinfection. The SB catalysts studied were prepared from three types of spent batteries' electrolytic pastes: Panasonic Super Hyper (SH), Panasonic Alkaline (AK) and yellow Rayovac (RV). Its characterization was made through FTIR, SEM, XRD, XRS and BET. The catalytic ozonation system was optimized through Central Composite Design (CCD) 22 with three replications at the central point, to determine the best catalyst dose and ozone dose (O3) to be applied. The degradation of 5 dyes and atrazine (ATZ) in ultrapure water (UW) and ATZ in secondary effluent (SE) and the disinfection was performed. The SB catalysts resulted in enhanced efficacy compared to ozonation alone. However, the AK showed better efficiency compared to the other catalysts in cleaner water matrices. When applied in SE the results showed equivalent efficiencies in comparison with single O3. The germination and elongation of Eruca sativa were not affected by the SB catalysts applied to O3, demonstrating that the effluent did not present toxicity either before or after the treatments. It highlights that the SB catalysts are capable of improving the organic pollutants removal.

N-Nitrosodimethylamine formation from anthropogenic nitrogenous compounds during preozonation and post-chloramination with characteristic low treatment dose.

One effective option to minimize N-nitrosodimethylamine (NDMA) in finished drinking water is to identify and control its precursors. However, previous works to identify significant precursors use formation potential (FP) tests using high doses to assure the maximum NDMA formation rather than the NDMA formation in finished waters. In this study, we applied characteristic low treatment doses of ozone (O3)-to-dissolved organic carbon (DOC) of target compounds of 0.8mg/mg and NH2Cl of 2.5 ± 0.2mg Cl2/L to evaluate the NDMAFP yields of organic compounds bearing N,N-dimethylamine (DMA) and N,N-dimethylhydrazine (DMH) during preozonation and post-chloramination. The results in pH-buffered Milli-Q water showed a significant decrease from ≤ 52% to non-detectable levels in the O3-NDMAFP yields of O3-reactive precursors (i.e., DMH-like compounds) after preozonation and post-chloramination. Similarly, a significant decrease from 0.5 to 12% to nonquantifiable levels was observed for the NH2Cl-NDMAFP yields of NH2Cl-reactive precursors; however, the NH2Cl-NDMAFP yields of N,N-dimethylbenzylamine (DMBzA)-like compounds only decreased from ~ 110 to ≤ 43%, suggesting that these compounds could contribute to NH2Cl-NDMAFPs even after preozonation. The effect of the matrix in sewage-effluent and lake water samples varied and was specific for precursors; for example, the O3-NDMAFP yield of 1,1,1',1'-tetramethyl-4,4'-(methylene-di-p-phenylene) disemicarbazide (TMDS), an important O3-reactive NDMA precursor, did not significantly decrease when tested in sewage-effluent samples. Based on the previous occurrence concentration of TMDS in sewage samples, we estimated an NDMAFP of ~ 315 ng/L. This estimate exceeds the guidance concentrations of NDMA (3-100ng/L), highlighting the importance of TMDS and its related compounds for NDMA formation.

Catalytic ozonation promoted by Mn-doped sludge-based catalyst treating refractory industrial wastewater

Attributed to the refractory characteristic of industrial wastewater, it usually needs advanced treatment. Moreover, massive hazardous activated waste sludge generated from wastewater treatment introduces additional ecological risks. In this study, sludge-based catalysts were prepared by doping Mn to treat typical refractory wastewater of petrochemical secondary wastewater. Results showed that the Mn-doped catalyst (PS-M700) prepared by pyrolysis at 700 °C was optimal for the catalytic ozonation of petrochemical secondary wastewater. The optimal ozone and catalyst dosage were 216 mg/L and 1.0 g/L, respectively. Catalytic ozonation of petrochemical secondary wastewater using PS-M700 showed an excellent TOC removal efficiency of 56.6 %. In addition, hydroxyl radicals (OH) played a major role in the catalytic ozonation of the petrochemical secondary wastewater. Results of excitation-emission matrix fluorescence spectroscopy showed that catalytic ozonation can further enhance the removal efficiency of not readily biodegradable compounds compared to ozone alone. Moreover, the catalytic ozonation process mainly targeted substances within the molecular weight (MW) < 1 kDa range in petrochemical secondary wastewater. In addition, transformation processes occurred between pollutants of different MW. Fourier Transform ion cyclotron resonance mass spectrometry showed that oxygen (CHO), nitrogen (CHONO) and sulfur (CHOS) containing contaminants were decreased by 6.0 % (2359 vs 2216), 34.9 % (2505 vs 1631) and 62.8 % (1227 vs 456). The present study shows the satisfactory prospect of a sustainable “wastes-treating-wastes” process for wastewater treatment.

Application of tryptophan-like fluorescence index to quantify the trace organic compounds removal in wastewater ozonation

The effectiveness of ozonation, one of the techniques known for destroying organic contaminants from wastewater, depends on the composition of the wastewater matrix. The required ozone (O3) dose is determined based on the target compounds during ozonation. Hydroxyl radicals are quantified using a probe compound. The para-chlorobenzoic acid (pCBA) is typically used as a probe compound to measure hydroxyl radicals. However, real-time measurement is impossible, as the analysis process consumes time and resources. This study aimed to evaluate the spectroscopic characteristics of various organic substances in wastewater ozonation through fluorescence excitation-emission matrix and parallel factor analysis. The study also demonstrated that real-time analyzable tryptophan-like fluorescence (TLF) can be used as a hydroxyl radical index. Importantly, the correlation between para-chlorobenzoic acid and TLF was derived, and the results showed a high correlation (R2 = 0.91), confirming the reliability of our findings. Seven trace organic compounds, classified based on their reactivity with O3 and hydroxyl radicals, were selected as target compounds and treated with O3. The TLF index was used as a model factor for the removal rate of the target compounds. The experimental and model values matched when the O3 dose was below 1.0 g O3 /g DOC (RMSE: 0.0445∼0.0895).

Unraveling the difference of sensitivity to ozone between non-hybrid native poplar and hybrid poplar clones: A flux-based dose-response analysis

Poplars are economically important tree crops and biologically important model plants, which are known to be sensitive to ozone (O3). Although surface O3 is considered as a significant global environmental issue because of its phytotoxicity and greenhouse effect, the knowledge of the dose-response (DR) relationships in poplars for the assessment of O3 risk is still limited. Hence, this study aimed at collecting data of studies with manipulative O3 exposures of poplars within FACE (Free Air Concentration Enhancement) and OTC (Open-Top Chamber) facilities. The datasets contain studies on hybrid poplar clones and a non-hybrid native poplar (Populus nigra L.) reporting both AOT40 (Accumulated exposure Over a Threshold of 40 ppb) and POD1 (Phytotoxic Ozone Dose above a threshold of 1 nmol m−2 Projected Leaf Area [PLA] s−1) to compare exposure- and flux-based indices. As a result, linear regression analysis showed that the flux-based POD1 was better than the exposure-based AOT40 to explain the biomass response of poplars to O3. From the DR relationships, a critical level (CL) of 5.7 mmol m−2 POD1 has been derived corresponding to 4% biomass growth reduction for hybrid poplar clones, which can be considered very sensitive to O3, while the non-hybrid native poplar was less sensitive to O3 (CL: 10.3 mmol m−2 POD1), although the potential risk of O3 for this taxon is still high due to very high stomatal conductance. Moreover, the different experimental settings (OTC vs. FACE) have affected the AOT40-based DR relationships but not the POD1-based DR relationships, suggesting that poplar responses to O3 were principally explained by stomatal O3 uptake regardless of the different experimental settings and exposure patterns. These results highlight the importance of the flux-based approach, especially when scaling up from experimental datasets to the O3 risk assessment for poplars at the regional or global scale.

Real-time ozonation monitoring and control in wastewater tertiary treatment: An ultraviolet-visible monitoring approach

To address the challenge of refractory organics removal in wastewater tertiary treatment, this study investigates the application of ozonation, coupled with Ultraviolet-Visible (UV–Vis) spectroscopy, for enhanced tertiary treatment in a wastewater treatment plant (WWTP) in Qingdao, China. Our approach integrates ozonation with real-time UV–Vis spectral monitoring to precisely control ozone dosing, targeting the effective degradation of persistent organics characterized by high Chemical Oxygen Demand (COD) values. Through the deployment of mathematical models, including Linear Discriminant Analysis (LDA) and Support Vector Machine (SVM), we developed a robust two-step ozone dosing control model. The model's efficacy is validated by its ability to predict the need for ozonation with a high degree of accuracy (94.29 % for LDA), significantly optimizing the ozonation process. Key findings indicate that this method not only achieves substantial removal of recalcitrant organics (with COD removal rates varying between 16 % and 71 %) but also offers considerable energy savings and operational cost reductions by adjusting ozone dosing in real-time based on water quality data. This study presents a novel, sustainable approach to improving WWTP efficiency and compliance, showcasing the potential of integrating advanced oxidation processes with precision monitoring techniques for environmental protection and water reuse initiatives.

Synthesis of surficial-modified green biochar catalyst generated by biogas residue biochar and potential application for catalytic ozonation degradation of ciprofloxacin

This study synthesized novel, green, and easily recoverable surface-modified economical catalysts via hydrothermal treatment (HT) successfully, utilizing biogas residue biochar (BRB), a food waste product from anaerobic fermentation, pyrolyzed at 500°C for 50 min. Using autoclaves, a total of six solutions were prepared, each having 1 g fine-grinded BRB, surficial modified by adding glycerol (GL) (10 or 20 mL) and SDI water (70 or 60 mL), and heated in an oven at 240°C, 180°C, and 120°C for 24 h. Afterward, the catalysts showed the potential for degradation of widely used emerging pollutants like ciprofloxacin. Taking advantage of catalytic surface modification, the catalytic ozonation degradation was more effective than that of a single ozonation. However, under similar conditions, catalyst amount 0.20 g, ozone dose 15 mg L-1, and ciprofloxacin 80 mg L-1, the performance of the 10 mL GL-180°C catalyst was excellent. It showed a 92.45% to 94.41% optimum removal rate in the 8–10 min interval. After five continuous cycles, the 10 mL GL-180°C catalyst exhibited excellent stability and reusability. XPS, FT-IR, BET, XRD, and SEM before and after the reaction confirmed the successful synthesis and degradation mechanism. A possible degradation pathway was unrevealed based on a liquid chromatography-mass spectrometer (LC-MS) and scavenger test, proving the significant roles of superoxide radicals (O2•-), hydroxyl radicals (•OH), and singlet oxygen (1O2). Further, Electron paramagnetic resonance (EPR) analysis confirmed the presence of active oxygen species. Subsequently, 10 mL GL-180°C showed promising degradation for the actual water environment, such as groundwater (73.55%) and river water (64.74%). This work provides a valuable economic strategy to convert biogas residue biochar into a low-cost catalyst for organic pollutant decomposition.

Pilot scale removal of organic micropollutants by combining ozonation with powdered activated carbon

ABSTRACT Pilot experiments were conducted to assess the removal of organic micropollutants from biologically treated wastewater at a municipal wastewater treatment plant in Sweden. Powdered activated carbon (PAC) was combined with a low dose of ozone added directly before the PAC contact tank, enabling ozone to react simultaneously with the PAC and the wastewater contaminants. This combination of ozone and PAC was compared to PAC or ozone alone. The process, which included coagulation/flocculation and ballasted high-rate lamella sedimentation, proved to be both robust and efficient for the removal of micropollutants. The addition of 1.3 mg PAC/mg DOC resulted in a 73% average reduction of micropollutants. With the addition of 0.13 mg O3/mg DOC, the reduction increased to 83%, which was similar to the outcome with the addition of 26 mg PAC/mg DOC without ozone. The process configuration and operating conditions did not lead to any detectable bromate formation despite relatively high influent bromide levels. The estimated operating costs for combining PAC with a low dose of ozone were significantly lower than for applying a higher PAC dose. Thus, this way of combining PAC with ozone seems to have several advantages with respect to treatment efficiency and operation.

Accumulation of Alpha-Synuclein and Increase in the Inflammatory Response in the substantia nigra, Jejunum, and Colon in a Model of O3 Pollution in Rats

This work aimed to study the effect of repeated exposure to low doses of ozone on alpha-synuclein and the inflammatory response in the substantia nigra, jejunum, and colon. Seventy-two male Wistar rats were divided into six groups. Each group received one of the following treatments: The control group was exposed to air. The ozone groups were exposed for 7, 15, 30, 60, and 90 days for 0.25 ppm for four hours daily. Afterward, they were anesthetized, and their tissues were extracted and processed using Western blotting, immunohistochemistry, and qPCR. The results indicated a significant increase in alpha-synuclein in the substantia nigra and jejunum from 7 to 60 days of exposure and an increase in NFκB from 7 to 90 days in the substantia nigra, while in the jejunum, a significant increase was observed at 7 and 15 days and a decrease at 60 and 90 days for the colon. Interleukin IL-17 showed an increase at 90 days in the substantia nigra in the jejunum and increases at 30 days and in the colon at 15 and 90 days. Exposure to ozone increases the presence of alpha-synuclein and induces the loss of regulation of the inflammatory response, which contributes significantly to degenerative processes.

Methylene blue (MB) removal from aqueous solution by alum; catalytic ozonation process

Textile wastewater is among the most polluted types of industrial waste. Wastewater treatment in the textile industry is notoriously difficult because of the use of complex chemicals and dyes in the textile production steps, and conventional methods are not enough to treat these. Textile wastewater, known for its high pollution levels, poses challenges for treatment due to complex chemicals and dyes. A comparative study was conducted on simple ozonation and catalytic ozonation (CO) using alum to degrade methylene blue (MB). The authors analyzed various factors like time, pH, catalyst loading and ozone dosages during the study. Results showed that catalytic activity in ozonation depends on pH and ozone flow. The maximum MB elimination was achieved at pH 6.6 and 200 V ozone flow. Scanning electron microscopy (SEM) was used to characterize the surface morphology of the catalyst, Fourier transform infrared spectroscopy (FTIR) was used to identify the important functional groups, and energy dispersive X-ray spectroscopy (EDS) was used to characterize the catalyst's elemental composition. Compared to simple ozonation, CO showed higher removal in the initial phase. Real textile wastewater analysis confirmed the effectiveness of alum catalysts in achieving significant removal of MB (87%) through this novel cost-efficient process.Graphical

Optimization of bromocresol green degradation using ozone micro bubbles: response surface analysis and techno-commercial aspects of a 75 kL/day scale-up plant

Degradation of bromocresol green in alcohol-water solution using ozone micron sized bubbles is reported. A high speed impeller is used to generate micro bubbles of ozone in liquid while ozone is generated using a commercial ozone generator. A 3-level-3-factor Box–Behnken experimental design is used to statistically identify relative importance of the operating parameters studied namely impeller speed, initial concentration of dye and treatment time. Ozone dosage is kept fixed at 4 g/h. Impeller speed is found to be the most dominant factor according to Analysis of Variance (ANOVA) calculations. Kinetics for degradation of bromocresol green in solution is also reported. A second order kinetics is seen to fit the experimental (concentration–time) data, corresponding value of rate constant being 0.0153 L/mg-s. Based on the laboratory scale data a detailed techno-commercial analysis of a scaled up (75 kL/day) plant for ozone based degradation of bromocresol is presented. All relevant economic indicators pertaining to the scaled up plant are reported. A specific treatment cost of Rs. 100/m3 of treated water yields a return on investment (ROI) of 68.77 and discounted payback period of 5 years.

Investigating the suitability of online flow cytometry for monitoring full-scale drinking water ozone system disinfection effectiveness

While online monitoring of physicochemical parameters has widely been incorporated into drinking water treatment systems, online microbial monitoring has lagged behind, resulting in the use of surrogate parameters (disinfectant residual, applied dose, concentration × time, CT) to assess disinfection system performance. Online flow cytometry (online FCM) allows for automated quantification of total and intact microbial cells. This study sought to investigate the feasibility of online FCM for full-scale drinking water ozone disinfection system performance monitoring. A water treatment plant with high lime solids turbidity in the ozone contactor influent was selected to evaluate the online FCM in challenging conditions. Total and intact cell counts were monitored for 40 days and compared to surrogate parameters (ozone residual, ozone dose, and CT) and grab sample assay results for cellular adenosine triphosphate (cATP), heterotrophic plate counts (HPC), impedance flow cytometry, and 16S rRNA gene sequencing. Online FCM provided insight into the dynamics of the full-scale ozone system, including offering early warning of increased contactor effluent cell concentrations, which was not observed using surrogate measures. Positive correlations were observed between online FCM intact cell counts and cATP levels (Kendall's tau=0.40), HPC (Kendall's tau=0.20), and impedance flow cytometry results (Kendall's tau=0.30). Though a strong correlation between log intact cell removal and CT was not observed, 16S rRNA gene sequencing results showed that passage through the ozone contactor significantly changed the microbial community (p < 0.05). Potential causes of the low overall cell inactivation in the contactor and the significant changes in the microbial community after ozonation include regrowth in the later chambers of the contactor and varied ozone resistance of drinking water microorganisms. This study demonstrates the suitability of direct, online microbial analysis for monitoring full-scale disinfection systems.

Preparation of CeO2 Supported on Graphite Catalyst and Its Catalytic Performance for Diethyl Phthalate Degradation during Ozonation

Catalysts for the efficient catalytic decomposition of ozone to generate reactive free radicals to oxidize pollutants are needed. The graphite-supported CeO2 catalyst was optimally prepared, and its activity in ozonation was evaluated using the degradation of diethyl phthalate (DEP) as an index. The stability of CeO2/graphite catalyst and the influence of operating conditions on its catalytic activity were investigated, and the mechanism of CeO2/graphite catalytic ozonation was analyzed. CeO2/graphite had the highest catalytic activity at a Ce load of 3.5% and a pyrolysis temperature of 400 °C with the DEP degradation efficiency of 75.0% and the total organic carbon (TOC) removal efficiency of 48.3%. No dissolution of active components was found during the repeated use of CeO2/graphite catalyst. The ozone dosage, catalyst dosage, initial pH, and reaction temperature have positive effects on the DEP degradation by CeO2/graphite catalytic ozonation. The presence of tert-butanol significantly inhibits the degradation of DEP at an initial pH of 3.0, 5.8, or 9.0, and the experimental results of the •OH probe compound pCBA indicate that the CeO2/graphite catalyst can efficiently convert ozone into •OH in solution. The DEP degradation in the CeO2/graphite catalytic ozonation mainly depends on the •OH in the bulk solution formed by ozone decomposition.

Ozone Strong Water Dosing as Optimized Ozonation Process for Micropollutants Reduction in Wastewater Treatment Plants

ABSTRACT Growing concern over potential ecotoxicological problems caused by micropollutants (MPs) in water has led to the application of adsorptive and oxidative advanced treatment technologies at European wastewater treatment plants (WWTPs). Direct dosage of gaseous ozone via diffusers or pump-injection systems is the most common large-scale process applied in water and wastewater treatment. Studies point out that MP removal may take place via the direct, very selective reaction with the ozone molecule as well as the indirect reaction with the very reactive but nonselective hydroxyl radicals. Several process parameters and set-ups may affect the MPs elimination and inhibit or even cause the formation of transformation products (TPs) such as bromate. This work compares an alternative ozone application procedure (the so-called ‘ozone strong water’ dosing – OSW) with standard systems regarding MP elimination, ozone consumption, reaction time, and required plant space. A full-scale OSW system was installed and operated at the WWTP Duisburg-Vierlinden. A significant reduction in the time required to achieve the maximum possible elimination was observed for all six MPs investigated, with a hydraulic reaction time of 8 min. According to a theoretical calculation, the reactor volume could be reduced by two-thirds of the installed volume.

Catalytic ozonation of 2, 4-dichlorophenoxyacetic acid wastewater by Fe-La@ZE catalyst

This study developed a salt-tolerant multimetal ozone catalyst Fe-La@Zeolite (Fe-La@ZE) and effectively catalyzed the ozone depletion of high-salinity 2,4-dichlorophenoxyacetic acid wastewater (2,4-D) and an entropy to evaluate the comprehensive gray cluster analysis model was created using catalytic ozonation conditions. Characterization results show that Fe-La@ZE has a developed pore structure and Fe and La are successfully loaded into the interior and surface of the zeolite support, which are in the form of α-Fe2O3 and La2O3. The COD removal rate of zeolite adsorption, ozone oxidation alone and catalyzed ozone oxidation with empty zeolite support are 4.9 %, 46.5 % and 57.5 %. The removal rates of COD, total phenol and 2,4-dichlorophenol by catalytic ozonation under the conditions of pH = 0.89, ozone dose of 0.2 g/L, catalyst filling rate of 10 % and height to diameter ratio of the reactor 6:1 are 84.2 %, 87.8 % and 99.0 % respectively. Hydroxy radicals (OH) and superoxide radicals (O2) are the main active substances that catalyze the degradation of 2,4-dichlorophenol in the ozone oxidation system. Water quality characterization shows that most phenolic organic compounds and macromolecular organic acids are broken down and converted into intermediate products. The comprehensive analysis model of entropy gray clustering is used to evaluate the operating condition data of the catalytic ozonation treatment of 2,4-dichlorophenoxyacetic acid wastewater with the Fe-La@ZE catalyst and determine the optimal operating condition.

Examining the response of Botrytis cinerea to aqueous ozone: inactivation kinetics, structure, physiology, and growth in different strawberries cultivars

ABSTRACT This work aimed to study the kinetics and mechanisms of Botrytis cinerea conidia inactivation by aqueous ozone treatments (2.5 ± 0.8 mg O3 L−1 and 4.2 ± 0.2 mg O3 L−1, 0.5–16 min), using conventional plate count technique, flow cytometry analysis (FCM), and transmission electron microscopy (TEM). The effect of treatments on the mold incidence on two artificially contaminated strawberries cultivars over refrigerated storage (6 ± 1 °C) was also investigated. The inactivation pattern of B. cinerea conidial suspensions depended on initial level of the microorganism, dissolved ozone concentration and treatment time. Non-linear survival curves were obtained and fitted successfully with the Weibullian model. FCM and TEM analysis revealed alterations in the physiological state and ultrastructure of ozonated conidia that depended on the ozone dose. Ozonation (4.4 mg O3L−1, 5–10 min) reduced B. cinerea incidence throughout storage in strawberries of cv. Fortuna, but no effect was found in cv. Aroma.

In-situ growth of Mn-Ni3S2 on nickel foam for catalytic ozonation of p-nitrophenol

In this study, a new catalyst for catalytic ozonation was obtained by in-situ growth of Mn-Ni3S2 nanosheets on the surface of nickel foam (NF). The full degradation of p-nitrophenol (PNP) was accomplished under optimal conditions in 40 min. The effects of material dosage, ozone dosage, pH and the presence of inorganic anions on the degradation efficiency of PNP were investigated. ESR analysis showed that singlet oxygen (1O2) and superoxide radical (O2•-) are the main contributors of PNP degradation. This study offers a new combination of supported catalysts with high efficiency and easy recovery, which provides a new idea for wastewater treatment.

MnO2-based capacitive system enhances ozone inactivation of bacteria by disrupting cell membrane

The application of ozone (O3) disinfection has been hindered by its low solubility in water and the formation of disinfection by-products (DBPs). In this study, capacitive disinfection is applied as a pre-treatment for O3 oxidation, in which manganese dioxide with a rambutan-like hollow spherical structure is used as the electrode to increase the charge density on the electrode surface. When a voltage is applied, the negative-charged microbes are attracted to the electrodes and killed by electrical interactions. The contact between microbes and capacitive electrodes leads to changes in cell permeability and burst of reactive oxygen species, thereby promoting the diffusion of O3 into the cells. After O3 penetrates the cell membrane, it can directly attack the cytoplasmic constituents, accelerating fatal and irreversible damage to pathogens. As a result, the performance of the capacitance-O3 process is proved better than the direct sum of the two individual process efficiencies. The design of capacitance-O3 system is beneficial to reduce the ozone dosage and DBPs with a broader inactivation spectrum, which is conducive to the application of ozone in primary water disinfection.

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.