Ozonation System Research Articles

Investigation of Giardia spp., Cryptosporidium spp. and Cyclospora cayetanensis in Samples Collected from Different Spring Waters Iğdır, Türkiye

In this study, it was aimed to investigate the physical and chemical properties of different spring waters and parasitic factors with different methods. This study was carried out on 69 water samples collected from different spring waters in and around Iğdır Province in April and June 2021. The samples were analyzed by native-Lugol, modified acid-fast staining, and nested polymerase chain reaction (nPCR). In addition, altitude (meter) and pressure (mmHg) measurements were made at the point where the water samples were taken. One or more parasites were detected in 27.5% of the 69 water samples examined. Only C. cayetanensis was found in 13% of the samples, only Cryptosporidium spp. in 10.1%, only Giardia spp. in 1.4%, only C. cayetanensis and Giardia spp. in 1.4%, only C. cayetanensis, Cryptosporidium spp., and Giardia spp. in 1.4%. Only Giardia spp. cyst (4.3%) was detected by the direct examination method. While C. cayetanensis and Cryptosporidium spp. oocysts were detected in 8.7% and 7.2% of the samples by the modified acid-fast staining method, C. cayetanensis was detected in 15.9% and Cryptosporidium spp. was detected in 11.6% of the samples by nPCR. When the C. cayetanensis and Cryptosporidium spp. positivity rates were compared according to the characteristics of the water, there was no statistical difference between the altitude, salinity, pH, mmHg, and temperature (kelvin) values, but a significant correlation was found between the amount of dissolved oxygen and Cryptosporidium spp. positivity (p=0.047). Cryptosporidium spp., C. cayetanensis, and G. intestinalis are important waterborne pathogens that can cause epidemics. It is our belief that in order to reduce the risk of contamination of these parasitic factors with spring waters, public awareness should be raised, infrastructures should be improved, and new water treatment techniques, such as ultraviolet, ozonation and monitoring systems, should be used.

Biocompatibility and Safety Assessment of Combined Topical Ozone and Antibiotics for Treatment of Infected Wounds.

Wound infections with antibiotic-resistant bacteria, particularly the Gram-negative strains, pose a substantial health risk for patients with limited treatment options. Recently topical administration of gaseous ozone and its combination with antibiotics through portable systems has been demonstrated to be a promising approach to eradicate commonly found Gram-negative strains of bacteria in wound infections. However, despite the significant impact of ozone in treating the growing number of antibiotic-resistant infections, uncontrolled and high concentrations of ozone can cause damage to the surrounding tissue. Hence, before such treatments could advance into clinical usage, it is paramount to identify appropriate levels of topical ozone that are effective in treating bacterial infections and safe for use in topical administration. To address this concern, we have conducted a series of in vivo studies to evaluate the efficacy and safety of a portable and wearable adjunct ozone and antibiotic wound therapy system. The concurrent ozone and antibiotics are applied through a wound interfaced gas permeable dressing coated with water-soluble nanofibers containing vancomycin and linezolid (traditionally used to treat Gram-positive infections) and connected to a portable ozone delivery system. The bactericidal properties of the combination therapy were evaluated on an ex vivo wound model infected with Pseudomonas aeruginosa, a common Gram-negative strain of bacteria found in many skin infections with high resistance to a wide range of currently available antibiotics. The results indicated that the optimized combination delivery of ozone (4 mg h-1) and topical antibiotic (200 μg cm-2) provided complete bacteria eradication after 6 h of treatment while having minimum cytotoxicity to human fibroblast cells. Furthermore, in vivo local and systemic toxicity studies (e.g., skin monitoring, skin histopathology, and blood analysis) on pig models showed no signs of adverse effects of ozone and antibiotic combination therapy even after 5 days of continuous administration. The confirmed efficacy and biosafety profile of the adjunct ozone and antibiotic therapy places it as a strong candidate for treating wound infection with antimicrobial-resistant bacteria and further pursuing human clinical trials.

Observational evidence for detrimental impact of inhaled ozone on human respiratory system

The detrimental influence of inhaled ozone on human respiratory system is ambiguous due to the complexity of dose response relationship between ozone and human respiratory system. This study collects inhaled ozone concentration and respiratory disease data from Shenzhen City to reveal the impact of ozone on respiratory diseases using the Generalized Additive Models (GAM) and Convergent Cross Mapping (CCM) method at the 95% confidence level. The result of GAM exhibits a partially significant lag effect on acute respiratory diseases in cumulative mode. Since the traditional correlation analysis is incapable of capturing causality, the CCM method is applied to examine whether the inhaled ozone affects human respiratory system. The results demonstrate that the inhaled ozone has a significant causative impact on hospitalization rates of both upper and lower respiratory diseases. Furthermore, the harmful causative effects of ozone to the human health are varied with gender and age. Females are more susceptible to inhaled ozone than males, probably because of the estrogen levels and the differential regulation of lung immune response. Adults are more sensitive to ozone exposure than children, potentially due to the fact that children need longer time to react to ozone stress than adults, and the elderly are more tolerant than adults and children, which may be related to pulmonary hypofunction of the elderly while has little correlation with ozone exposure.

Coupling ozonation with hydrogen peroxide and chemically enhanced primary treatment for advanced treatment of grey water

Grey water is a valuable water source due to its high-volume generation. This study was conducted with grey water that was obtained from a hotel with 1000 inhabitants and average flowrate of 40 m3/day. The main objective of the study was to determine the optimum operational conditions for ozonation process in terms of micropollutant removal along with conventional parameters and to enhance the removal efficiency of ozonation process by coupling with hydrogen peroxide or chemically enhanced primary treatment (CEPT) process. The results indicated that the COD removal efficiencies were around 37% by both sole ozonation and peroxone processes. However, CEPT+ozonation process increased the COD removal efficiency to 71%. On the other hand, TSS removal efficiency by peroxone and CEPT+ozonation processes were 57% and 89%, while TP removal efficiencies were 26% and 74%, respectively. All micropollutants that were detected in grey water, were removed until the limit of detection (LOQ) with all treatment processes. Overall evaluation of the results indicated that CEPT combined with the ozonation process was more effective in terms of removal of conventional parameters compared to sole ozonation and peroxone processes. Therefore, CEPT+ozonation process with the optimum ozone dosage and contact time is recommended to increase the possibility to reuse the treated grey water. A feasibility analysis was conducted for optimum ozonation mode and CEPT+ozonation, and the results revealed that unit total cost and unit operational cost for ozonation system was 0.027 $/m3 and 0.01 $/m3, respectively. The unit operational cost for CEPT+ozonation system was 0.124 $/m3.

Effects of Cold Plasma and Ozone Water Treatment on Micronutrient Solubility

Cold plasma and ozone sanitation of irrigation solutions can oxidize both microbes and non-target micronutrients because their high oxidation-reduction potential (ORP) is a non-selective mode of action. The objective of this study was to evaluate the effects of cold plasma and ozone treatment on oxidation of iron and manganese in nutrient solutions containing one of four iron chelates (iron-ethylenediaminetetraacetic acid (Fe-EDTA), iron-diethylenetriaminepentaacetic acid (Fe-DTPA), iron-ethylenediamine-N,N′-bis(2-hydroxyphenylacetic acid) (Fe-EDDHA), and hydroxybenzyl ethylenediamine (Fe-HBED)). Nutrient solutions were recirculated through the cold plasma or ozone system until the ORP reached 700 mV. The concentrations of total dissolved iron, manganese, and chelated iron were measured before and after passing through the treatment systems. Both cold plasma and ozone oxidized chelates and decreased the solubility of iron and manganese. Cold plasma and ozone had similar effects on micronutrients, pH, electrical conductivity, and dissolved oxygen at a standardized target ORP of 700 mV. Fe-EDTA was the most resistant chelate to oxidation. With Fe-EDTA, ORP increased more quickly, and the concentration of chelated Fe decreased less with the increasing ORP over time compared with Fe-DTPA, Fe-EDDHA, and Fe-HBED. The concentration of chelated Fe decreased by up to 80% for EDDHA at 700 mV compared with a 20% decrease for EDTA. The concentration of Mn decreased by up to 85% at 700 mV. The design of water treatment with cold plasma or ozone therefore requires consideration of secondary effects on micronutrients. The treatment dosage, flow rate, and nutrient solution at a particular grower operation are likely to affect the quantity of micronutrient fertilizer that needs to be supplemented following treatment. Use of Fe-EDTA is one strategy to reduce the loss of iron and increase residual ORP that is available for sanitation.

The special mechanisms of quasi-complexation and enhanced effect of “·OH action zone” in activated carbon combined ozonation

Activated carbon (AC) is an excellent adsorbent and is widely employed as a catalyst in catalytic ozonation. However, the massive change in surface oxygen groups on AC before and after ozonation in this research indicated that AC was not a real catalyst. Moreover, the lower oxalic acid removal effect and the observed hydroxyl radicals (·OH) accumulative amount of pre-oxidative AC combined ozonation confirmed that AC functioned as an activator. We investigated the removal trend of oxalic acid in AC-activated ozonation under different pH, and it was consistent with its adsorption via adjusting the oxalic acid adsorbed on AC. Despite the accumulation concentration of ·OH reaching the highest value at pH = 4.7, the activated ozonation did not perform best. Considering the extremely short life of ·OH in an aqueous solution, an “action zone” existed, which was the effective region for ·OH to react with organics. This result proved that the AC adsorption would concentrate organics in the “action zone”, thus improving the degradation of organic contaminants. The solution containing oxalic acid had a higher accumulative concentration of ·OH than without oxalic acid, which meant a previously neglected pathway existed to produce ·OH. In addition, C2O4·- was reported in the solution containing AC, oxalic acid, and oxygen. Thus, the quasi-complexation reaction might occur between AC, oxalic acid, and oxygen. Overall, this study disclosed distinct mechanisms due to AC adsorption in the AC combined ozonation system.

Enhanced degradation of cefalexin using Co2SnO4@rGO as an effective peroxymonosulfate activator in hybrid ozonation system

This study successfully developed a nanocomposite catalyst (Co2SnO4 @rGO) at optimal composite ratio of 2:1 between Co2SnO4 and GO for effectively activation of peroxymonosulfate (PMS) to degrade cefalexin (CFX) from water by hybrid ozonation system (O3/Co2SnO4 @rGO/PMS). The CFX removal efficiency was compared in three oxidation systems, including O3, Co2SnO4 @rGO/PMS and O3/Co2SnO4 @rGO/PMS under various operational conditions. The effect of co-existing anions and scavengers was studied to determine the CFX removal mechanisms. The characteristics of catalyst were analyzed using SBET, SEM, EDS and mapping, XRD, FTIR and pHPZC. The results illustrated that supplementation of O3 into Co2SnO4 @rGO/PMS system exhibited the highest degradation and mineralization efficiencies of CFX, reaching 99.93% and 67.03%, respectively under optimal operational conditions. At this condition, the CFX degradation and mineralization rates in O3/ Co2SnO4 @rGO/PMS system were higher than those in Co2SnO4 @rGO/PMS system by 2.8 and 1.32 times, respectively, thanks to synergistic effect of O3 and Co2SnO4 @rGO/PMS in the same reactor. The CFX removal mechanisms were proposed through both pathways: non-radical and radical pathway. The non-radical mechanism was through singlet oxygen (1O2) and radical pathway was via the free radicals of *OH, *SO4- and *O2. The scavenging experiments further confirmed CFX removal mechanism was through both non-radical and radical pathways. Among them, the 1O2 was predominately species in removal of CFX. Besides, the Co2SnO4 @rGO catalyst exhibited a high reusability over four consecutive catalytic cycles. These findings demonstrated the occurrence of O3 and Co2SnO4 @rGO in hybrid ozonation system effectively activated PMS to enhance CFX removal from wastewater.

Disability adjusted life years-oriented assessment of Cryptosporidium parvum inactivation with a Point-of-Use ozonation system

Disability adjusted life years-oriented assessment of Cryptosporidium parvum inactivation with a Point-of-Use ozonation system

Pilot-scale study and biochemical verification of salt-tolerant catalyst Fe-Bi@γ-Al2O3 for catalytic ozonation of high-salinity wastewater

In this study, Fe-Bi@ γ-Al2O3 was used as a catalyst to construct a heterogeneous catalytic ozonation system for the treatment of high-salinity organic wastewater and its biochemical verification was studied. The optimum operating conditions and degradation mechanism of Fe-Bi@ γ-Al2O3 catalytic ozonation of high salinity wastewater were systematically investigated. The biodegradability of wastewater before and after treatment was also studied. Under the optimum operating conditions of ozone dosage of 160 mg/L, catalyst filling rate of 15%, ratio of height to diameter of 15, hydraulic retention time of 210 min and recycle ratio of 500%, the removal rate of COD is 45.13%. The mechanical strength of Fe-Bi@ γ-Al2O3 catalyst is almost unchanged after being reused for 20 times. The results of Ultraviolet and visible spectrophotometry (UV-Vis), 3D (Three-Dimensional)-fluorescence and Gas Chromatography-Mass Spectrometer (GC-MS)showed that humus, fulvic acid and undissolved microbial organic matter were degraded. In the biochemical verification experiment, after the high salinity wastewater was used to impact the bio-reactor, the mixed liquor suspended solids (MLSS) was basically stable at 9597 mg/L, 8856 mg/L, 9414 mg/L and 8741 mg/L, and the mixed liquor volatile suspended solids (MLVSS) was basically stable at 7042 mg/L, 6940 mg/L, 6949 mg/L and 6519 mg/L. The dissolved oxygen (DO) in the four reactors were 2.9 mg/L, 3.48 mg/L, 3.6 mg/L and 2.92 mg/L respectively, and the sludge Volume Index (SVI30) were 93 mL/g, 98 mL/g, 93 mL/g and 91 mL/g respectively. After two cycles (20d) of 30% high salinity wastewater, the chemical oxygen demand (COD) removal rates of the four reactors were 78%, 84%, 86% and 91%, respectively. When the reaction time is 40 min, the BOD5/COD (B/C) value of the high-salinity wastewater reaches 0.91, and the biodegradability of the wastewater is improved significantly. Scanning electron microscope (SEM) showed that the granular sludge in the reactor had compact structure and smooth surface, and there were a lot of fungi and filamentous microorganisms on the sludge surface.in that condition of salinity stress, the microbial community in the activate sludge changed to a great extent, and Proteobacteria and Bacteroidetes became the main phylum. The Fe-Bi@ γγ-Al2O3 catalyst has good catalytic performance and can be used for deep treatment of high-salt organic wastewater.

Research Progress of Iron-Based Catalysts in Ozonation Wastewater Treatment

On account of the rich contents of iron-based catalysts, low preparation costs, and good effects, they play important roles in various fields of water treatment. There are many kinds of iron oxides, which have been employed in catalytic ozone oxidation processes. However, a thorough analysis of their syntheses, characterization techniques, reactions affecting variables, and mechanistic applications is lacking in the catalytic ozone oxidation sector. It is necessary to search for the catalytic efficiencies of different types of iron-based catalysts in the ozone system and elucidate the activation mechanisms of hydroxyl radicals by iron-based catalysts. In this paper, the synthesis methods, characterization techniques, and practical application fields are summarized in detail. The catalytic performances of iron-based catalysts in the ozone system are explored. The effects of solution pH, reaction temperature, catalyst addition amount, ozone concentration, and inorganic anions on the degradations of organic pollutants and the stability of an iron-based catalyst/oxidant system are also discussed. The activation mechanisms of free radicals and the removal mechanisms of organic pollutants in the iron-based catalyst/ozone system are revealed by a detection method, characterization technology, and theoretical analysis. The potential preparation methods, practical applications, auxiliary technologies, and influences on ozone catalysis are prospected.

Catalytic Ozonation for Pulp and Paper Mill Wastewater Treatment: COD Reduction and Organic Matter Degradation Mechanism

Rapid degradation of pulping and papermaking wastewater in a pulp and paper mill is crucial for recycling purposes yet challenging to achieve. The purpose of this research is to provide a technical guide for the ozone degradation treatment process of pulp and paper mill wastewater and to explore the reaction mechanism of dissolved and colloidal substances (DCSs). This study is vital for effectively treating pulp and paper mill wastewater through ozonation. In the catalytic ozonation process to treat pulp and paper mill wastewater, a polyurethane sponge loaded with titanium dioxide was used as a catalyst. The optimal process conditions were determined to be 8 min of treatment time, a 16 mg/L ozone concentration, pH 9, and a 7.5% catalyst filling ratio. The COD reduction under these conditions is approximately 52%. The catalytic ozonation system, according to the FI-IR and GC-MS analyses, could degrade the large-molecule volatile organic compounds in the raw wastewater into small-molecule substances. Furthermore, the relative content of common DCSs in paper wastewater, such as palmitic acid and stilbene, could be reduced. The catalytic ozonation system is more effective for treating refractory organic compounds and has a higher COD reduction than the ozonation system.

Ozonation for oxidation and transformation of pharmaceuticals in Arroio Diluvio River in Southern Brazil

ABSTRACT Pharmaceuticals are often found in the water environment and are not completely degraded by conventional treatment processes. There are some techniques, such as advanced oxidative processes (AOPs), which can promote, in addition to the total removal of contaminants, their mineralization, transforming them into CO2 and water. Thus, the objective of this work was to evaluate the mineralization capacity of the emerging pollutants caffeine and ampicillin, present in a real aqueous matrix, through ozonation. Factorial planning was carried out by Central Composite Design (CCD) under the Response Surface Methodology (RSM). Water samples were collected from Arroio Dilúvio, a river that cuts through the city of Porto Alegre (RS – Brazil), which receives domestic, hospital, and industrial effluents in nature. The experiments were conducted from the analysis of the influence of pH, time, and ozone flow rate variables. The ozonation system consisted of an oxygen concentrator, an ozone generator, and a gas washer bottle. With removals of caffeine and ampicillin around 100 and 99.7%, respectively, a mineralization of 30.8% was also obtained under conditions of pH 8, with an applied ozone dosage of 830 mg.L−1. In this process, the gas phase concentration was at 16.7 mg.L−1 when applied to 200 mL sample for 10 minutes and ozone flow rate of 1 L.min−1. A linear relationship was observed between the real and predicted values, and it has been shown that the relationship of the residual plot confirmed a sufficient approximation of the method for the optimization process. Finally, the desirability function showed adequate operating conditions for the mineralization of compounds by ozonation. Therefore, it is considered that this technique is effective for the mineralization of the pharmaceuticals studied, and can be applied as a way of treating a contaminated real matrix.

Ecotoxicity and resistance genes induction changing of antibiotic tetracycline degradation products dominated by differential free radicals

Studying the ecological risks of antibiotics and their degradation products is of great importance to water environment security and advanced oxidation processes (AOPs) development. This work studied the changes and internal influencing mechanisms of ecotoxicity and the capacity for inducing antibiotic resistance genes (ARGs) shown by the tetracycline (TC) degradation products generated in AOPs with differential free radicals. Under the action of superoxide radicals and singlet oxygen in the ozone system, and sulfate and hydroxyl radicals in the thermally activated potassium persulfate system, TC exhibited differential degradation pathways and resulted in the differential growth inhibition trends on the determined strains. Microcosm experiments combined with metagenomics were also performed to analyze the remarkable changes in the TC resistance genes tetA (60), tetT, and otr(B) induced by the degradation products and ARG hosts in the natural water environment. Microcosm experiments exhibited that the microbial community in actual water have changed significantly with the addition of TC and degradation intermediates. Furthermore, the richness of genes related to oxidative stress was investigated to discuss the effect on reactive oxygen species production and SOS response caused by TC and its intermediates.

Construction of an underwater plasma and Fenton hybrid system for the rapid oxidation of organic dyes and antibiotics

In this study, the decomposition efficiency and oxidation rate of organic pollutants were improved using a combination of a dielectric barrier discharge (DBD) plasma system and Fe3O4 Fenton catalyst, a representative advanced oxidation process (AOP). The combined plasma Fenton system showed >99 % degradation of 200 mg L−1 dyes within 35 min, while other AOP systems achieved lesser degradation of the same concentration of dyes in 40 min: no degradation in the Fe3O4 Fenton system and <25 % in the Ozone(O3) system. Additionally, >92 % of tetracycline and ciprofloxacin (TC, CIP: 10 mg L−1) was effectively degraded in the plasma Fenton system within 5 min, in contrast to the Fe3O4 Fenton system. The rapid degradation of organic compounds was attributed to various oxidant species, including O3, H2O2, and OH, from the reaction between the plasma electrode and Fenton catalyst. By analyzing chemically active species and interfacial reactions of the multiple-hole DBD underwater plasma Fenton system, we improved the accessibility of AOP element technology and proposed a research foundation for the decomposition reaction, thereby providing a theoretical basis for developing this technology.

Enhanced Mass Transfer of Ozone and Emerging Pollutants through a Gas-Solid-Liquid Reaction Interface for Efficient Water Decontamination.

Ozone (O3), as an environmentally friendly oxidant, is widely used to remove emerging pollutants and ensure the safety of the water supply, whereas the restricted accessibility of O3 and limited collision frequency between pollutants and O3 will inevitably reduce the ozonation efficiency. To promote the chemical reactions between O3 and target pollutants, here we developed a novel gas-solid-liquid reaction interface dominated triphase ozonation system using a functional hydrophobic membrane with an adsorption layer as the O3 distributor and place where chemical reactions occurred. In the triphase system, the functional hydrophobic membrane simultaneously improved the interface adsorption performance of emerging pollutants and the access pathway of O3, leading to a marked enhancement of interfacial pollutant concentration and O3 levels. These synergistic qualities result in high ciprofloxacin (CIP) removal efficiency (94.39%) and fast apparent reaction rate constant (kapp, 2.75 × 10-2 min-1) versus a traditional O3 process (41.82% and 0.48 × 10-2 min-1, respectively). In addition, this triphase system was an advanced oxidation process involving radical participation and showed excellent degradation performance of multiple emerging pollutants. Our findings highlight the importance of gas-solid-liquid triphase reaction interface design and provide new insight into the efficient removal of emerging pollutants by the ozonation process.

Synergistic effects of simultaneous coupling ozonation and biodegradation for coking wastewater treatment: Advances in COD removal, toxic elimination, and microbial regulation

Coking wastewater contains high concentrations of cyanide, phenols, pyridine, quinoline, and polycyclic aromatic hydrocarbons. Its high toxicity and low biodegradability leads to long hydraulic retention time of biological process and high cost of advanced oxidation process. In this study, the simultaneous combination of ozonation and biodegradation (SCOB) was proposed to treat coking wastewater. Through this process, ozonation breaks the refractory organics, and the biodegradable intermediates are rapidly mineralized by microorganisms protected by porous carriers. Thus, the performances of SCOB, individual biodegradation and ozonation systems were compared. The long-term stability of the SCOB system was evaluated, the contributions of ozonation and biodegradation were analyzed, and their synergistic mechanisms were elaborated. Results showed that biological activity was inhibited in the biodegradation system, and chemical oxygen demand (COD) removal was only 27.6% for the ozonation system. COD and total phenol removal of SCOB system reached 48.5% and 79.3%, respectively, and its kinetic degradation constant of COD was 55.6% higher than that of the ozonation system. Ozonation contributed to the oxidation of organics with unsaturated functional groups as well as soluble microbial products (SMPs), causing the effluent toxicity and chroma to decrease by 82.7% and 270 times, respectively. The higher abundances of microorganisms and functions were enriched in the core of carrier, which became dominant region for biodegradation. Consequently, COD removal of the SCOB system stabilized at >80% for real coking wastewater treatment, confirming its promising potential for the treatment of highly polluted industrial wastewater.

Switching the primary mechanism from a radical to a nonradical pathway in electrocatalytic ozonation by onsite alternating anode and cathode

Concurrently elevating the degradation efficiency of pollutants and realizing the reduction of iron sludge in Fe-based catalytic ozonation is important but still challenging. Herein, we developed an electrocatalytic ozonation (ECO) system with iron plate cathode and graphite felt anode (ECO-Fe-cathode), which was free from added chemical reagents. Unlike the iron plate as a sacrificial anode in the ECO (ECO-Fe-anode) system, this delicately designed system shows a much higher degradation rate of ibuprofen (kobs = 1.490 min−1) than that of the ECO-Fe-anode system (kobs = 0.345 min−1). Simultaneously, the effluent was totally limpid without the corrosion of iron plates and the formation of iron sludge in the ECO-Fe-cathode system. Unexpectedly, the generation of singlet oxygen (1O2) which is indirectly generated by the single-electron transfer derived from superoxide ion (O2•-) is the primary reactive oxygen species (ROS) in the ECO-Fe-cathode system, which is different from the ECO-Fe-anode system with hydroxyl radicals (•OH). Moreover, linear sweep voltammetry (LSV) was applied to reveal the oxygen evolution reaction (OER) performance of the iron plate and graphite felt, and the results showed that graphite felt as anode has better electrocatalytic performance. The electrochemical analysis and density functional theory (DFT) calculation revealed that ozone adsorbed on the iron plate surface is more conducive to facilitating and triggering subsequent reactions. Finally, the different degradation pathways of ibuprofen in both systems were proposed. This work represents a fundamental breakthrough toward the design of an efficient and harmless ECO system for wastewater treatment.

Tentative exploration on water-promoted catalytic ozonation of Cl-VOCs and feasibility of application in complex flue gas over monolithic cobalt catalyst

It is still challenge to avoid Cl poisoning and achieve efficient elimination of Cl-VOCs at low temperature. This paper tentatively explored water-promoted catalytic ozonation of Cl-VOCs and feasibility of application in complex flue gas over monolithic cobalt catalyst. O 3 decomposition and Cl-VOCs ozonation occur simultaneously but the active radicals and intermediates from O 3 decomposition and Cl-VOCs ozonation have competitive effects on oxygen vacancies. Most interestingly, presence of water vapor and NO, as well as lowering temperature to 50 o C further promote catalytic ozonation of Cl-VOCs. Moisture vapor facilitates desorption of surficial Cl species and deep oxidation by washing effect and provision of additional H source to attain higher conversion and less byproducts. Especially, 1 vol.% water vapor attains ~10% elevation in CH 2 Cl 2 conversion and almost 10%~25% improvement in mineralization rate. NO ozonation generates NO 3 related radicals with strong oxidability to enhance Cl-VOCs conversion and inhibit polychlorinated byproducts formation. Lower temperature promotes adsorption of the above-mentioned active radicals and intermediates to prolong the contact time, thus attaining higher conversion, ca. 100% conversion with O 3 /CH 2 Cl 2 of 12.5 at 50 o C. SO 2 and Ca cause severe deactivation on catalytic ozonation that requires higher O 3 input, which should be attributed to the occupation of active sites and attenuation of acidity. Above all, this paper reports an effective and practical approach for Cl-VOCs elimination in flue gas with potential to simultaneous remove NO. • The monolithic catalyst is firstly used for catalytic ozonation system. • CoO x @Ni attains 90% DCM conversion with O 3 /DCM=6.0 under humid condition at 120 o C. • Water vapor enhances the performance of Cl-VOCs catalytic ozonation over CoO x @Ni. • Simultaneous removal of NO and Cl-VOCs can be achieved during catalytic ozonation.

Catalytic Ozonation of Norfloxacin Using Co-Mn/CeO2 as a Multi-Component Composite Catalyst

In this study, a Co-Mn/CeO2 composite was prepared through a facile sol-gel method and used as an efficient catalyst for the ozonation of norfloxacin (NOR). The Co-Mn/CeO2 composite was characterized via XRD, SEM, BET and XPS analysis. The catalytic ozonation of NOR by Co-Mn/CeO2 under different conditions was systematically investigated, including the effect of the initial solution’s pH, Co-Mn/CeO2 composite dose, O3 dose and NOR concentration on degradation kinetics. Only about 3.33% of total organic carbon (TOC) and 72.17% of NOR could be removed within 150 min by single ozonation under the conditions of 60 mg/L of NOR and 200 mL/min of O3 at pH= 7 and room temperature, whereas in the presence of 0.60 g/L of the Co-Mn/CeO2 composite under the same conditions, 87.24% NOR removal was obtained through the catalytic ozonation process. The results showed that catalytic ozonation with the Co-Mn/CeO2 composite could effectively enhance the degradation and mineralization of NOR compared to a single ozonation system alone. The catalytic performance of CeO2 was significantly improved by the modification with Mn and Co. Co-Mn/CeO2 represents a promising way to prepare efficient catalysts for the catalytic ozonation of organic polluted water. The removal efficiency of NOR in five cycles indicates that Co-Mn/CeO2 is stable and recyclable for catalytic ozonation in water treatment.

Photocatalytic ozonation inactivation of bioaerosols by NiFeOOH nanosheets in situ grown on nickel foam

Inactivation of bioaerosols is critical to prevent the spread of microbial pathogens in air. Photocatalytic inactivation processes are environmental friendliness, while time-consuming and insufficient reactive oxygen species (ROSs) generation to irreversibly inactivate bacteria in bioaerosols. In this work, a novel photocatalytic ozonation (PCO) system was constructed, consisting of in situ grown NiFeOOH nanosheets on nickel foam (NiFeOOH NSs/NF) and trace concentration of ozone (O3). Specifically, the PCO system exhibited remarkable photocatalytic inactivation efficiency (99.99%) within an ultrashort retention time of 8.07 s (RH = 90%) while no bacteria survived after 24-h cultivation. The irreversible inactivation of bacteria in this PCO system attributes to the synergistic effect of physical destruction by NiFeOOH NSs/NF and oxidative damage by photogenerated ROSs. This research provides a better alternative for efficient inactivation of bioaerosols and opens the door for the application of PCO system in reducing the exposure risk of bioaerosols.