Ozone Microbubbles Research Articles

Morphologically-different cells and colonies cause distinctive performance of coagulative colloidal ozone microbubbles in simultaneously removing bloom-forming cyanobacteria and microcystin-LR

Morphology, the important feature of bloom-forming cyanobacteria, was studied for its impacts on the harmful cyanobacterial bloom (HCB) treatment by coagulative colloidal ozone microbubbles (CCOMBs). The globally-appeared HCB species – Microcystis aeruginosa (spherical cells, block mass colonies), Microcystis panniformis (spherical cells, flat penniform-like colonies) and Anabaena flos-aquae (filamentous morphology) were chosen as representative species. CCOMBs were generated by modifying the bubble surface and the gas core with coagulant and ozone, respectively. The removal of spherical cells and filaments was > 99.5% and ≤ 34.6%, individually, and the latter was ascribed to chain breakage. CCOMBs collected Microcystis panniformis via complexing with the fluorescent and non-fluorescent functional groups of cell colonies but captured Anabaena flos-aquae through the fluorescent ones. More Microcystis aeruginosa got membrane-damaged than Microcystis panniformis; nevertheless, the microcystin-LR (MC-LR) removal was guaranteed through efficiently oxidizing the released MC-LR. Although the outer peptidoglycan sheet of Anabaena flos-aquae was destroyed, the inner cyte membrane remained intact, preventing intracellular MC-LR from releasing. The HCBs dominated by single species with spherical cells were more readily treated than those with co-occurred species. The toxicological tests imply that, as a robust tool for HCB treatment, the CCOMB technology could be eco-environmentally friendly to the aquatic environment.

Process intensification of the ozone-liquid mass transfer in ultrasonic cavitation-rotational flow interaction coupled-field: Optimization and application

A study on the intensification of ozone mass transfer in rotational flow field and UC-RF coupled-field was conducted. Two important operational parameters namely liquid flow rate and ultrasonic power, were optimized with regard to the ozone mass transfer efficiency. Results showed that the mass transfer coefficient (KLa) increased with liquid flow rate (up to 14 L min−1) and ultrasonic power (up to 1000 W). The maximum KLa value (1.0258 min−1) was obtained with the UC-RF coupled-field. Moreover, the reinforcement of mass transfer efficiency was promoted by the rotational flow field and UC-RF coupled-field due to the increase in the ozone-liquid contact area, intensification of turbulence, acceleration of interface renewal, and extension of residence time. Ozone microbubbles rose in the reactor in a spiral manner. In addition, the microbubbles produced in the rotational flow field served as cavitation nucleus that helped to generate the cavitation effect. The effective degradation of di-butyl phthalate (DBP) confirmed that its removal was improved by the ozone-liquid mass transfer and the promotion of hydroxyl radicals (·OH) production. The synergistic effect of DBP degradation via ultrasound-enhanced ozonation was significant.

Degradation of Methyl Orange by ozone microbubble process with packing in the bubble column reactor

ABSTRACT The performance of the ozone microbubble(MB) process for the degradation of Methyl Orange (MO) in a bubble column reactor with added packing was investigated. The highest decolorization efficiency of 96.04% was achieved by the ozone MB process with packing, which was 10.17% and 62.02% higher than that of the ozone MB process without packing and the ozone millimeter bubble(MLB) process, respectively while keeping other operating parameters the same. In addition, the saturation gas holdup, ozone mass transfer coefficient, and decolorization rate constant of the ozone MB process with packing were 15.32%, 0.260 min−1, and 0.027 min−1, respectively, which were much better than those of the ozone MB process without packing and the ozone MLB process. The study also suggested that within a certain porosity range, the types of packings did not affect the performance of the ozone MB process in the degradation of MO. Moreover, the optimum operating conditions were initial concentration of MO of 30 mg/L, initial pH of 3, circulating liquid flow of 75 L/h, and ozone dosage of 0.56 mg/L. The decolorization efficiency was 99.28% within 120 min.

Degradation of Ciprofloxacin in Aqueous Solution Using Ozone Microbubbles: Spectroscopic, Kinetics, and Antibacterial Analysis

Degradation of Ciprofloxacin in Aqueous Solution Using Ozone Microbubbles: Spectroscopic, Kinetics, and Antibacterial Analysis

Ozone microbubbles treatment with different gas–liquid mixing conditions and its application on printing and dyeing wastewater and Escherichia coli

Ozone microbubbles treatment with different gas–liquid mixing conditions and its application on printing and dyeing wastewater and Escherichia coli

Direct Oxidation of Antibiotics from Aqueous Solution by Ozonation with Microbubbles

in this research, antibiotics (tetracycline, ceftriaxone, and metronidazole) were removed in a batch reactor each one separately and together using ozone microbubbles (OMBs) method. The antibiotic removal efficiency was analyzed under different reaction conditions, including initial solution pH, ozonation time, ozone production rate, and initial antibiotic concentration. It was found from the experiments that the elimination of antibiotics by ozone microbubbles was higher at the basal medium between (7-8). In addition, as the ozone production rate was raised from (3.33-16.66) mg/min, the removal efficiency increased, as did the antibiotic concentration (1-100) PPM. Also, the removal tests were carried out under optimal conditions using the conventional ozonation method, and the microbubble technology and the results were compared under the same operating conditions. The microbubbles were found to save a lot of time and reduce the amount of ozone used.

Effect of pH on Decomposition of Organic Compounds Using Ozone Microbubble Water

Microbubbles are tiny bubbles with a particle size of 1 - 100 μm. Microbubbles have been reported that the gas dissolving ability is excellent and hydroxyl radical generates when microbubbles collapse in water. On the other hand, ozone is a gas with high oxidation power and eventually decomposes into oxygen. So, ozone is environmentally friendly. Therefore, we thought that ozone microbubbles water, in which ozone is dissolved in microbubbles water, could be used to efficiently decompose persistent organic compounds while being environmentally friendly. In this study, we evaluated the decomposition of phenol, an object subject to wastewater regulation, by ozone water and ozone microbubbles water. At a constant dissolved ozone concentration, we could not confirm the effect of microbubbles in decomposing phenol. Also, under the same conditions, when the pH was changed, the effect of microbubbles could not be confirmed. However, under basic conditions, phenol was decomposed the most because of self-decomposition reaction of ozone. Therefore, the effect of microbubbles could not be confirmed in the phenol degradation by ozone microbubbles in this experiment.

A comparative study on the removal of dimethyl sulfoxide from water using microbubbles and millibubbles of ozone

Ozone-based microbubble-aided technology has been gaining popularity as a new potential alternative method for the oxidation of organic pollutants present in water/wastewater. In this work, the potential of the ozone microbubbles (OMBs) for the oxidation of dimethyl sulfoxide (DMSO) was investigated, and the results were compared with those of the conventional ozone millibubbles (OMLBs). Keeping constant other operational parameters, the OMLBs needed a longer time for complete removal of DMSO, and hence a higher consumption of ozone took place. Therefore, a higher stoichiometric ratios of ozone consumed to the DMSO removed was obtained for the OMLBs. Higher ozone utilization efficiencies were observed for the OMBs (i.e., 65–79 %) than the OMLBs (i.e., 21–48 %). Coupling of H2O2 with the ozonation systems improved the oxidation of DMSO by enhancing the formation of ·OH. Conversely, a large dosage of H2O2 had a negative effect. The degradation of DMSO to methane sulfonic acid (MSA) was achieved via two paths (i.e., direct conversion to MSA by the reaction with ·OH, and a two-stage conversion via the formation of DMSO2 by molecular ozone, followed by further oxidation of DMSO2 to MSA by the ·OH). In terms of the TOC removal efficiency, the effectiveness was in the following order: OMLBs < OMLBs/H2O2 < OMBs < OMBs/H2O2. Oxidation of DMSO by ozone followed an overall second-order kinetics for the OMBs, and first-order kinetics for the OMLB system. Higher enhancement factor and volumetric mass transfer coefficient were obtained for the OMBs as compared to OMLBs.

Treatment of simulated printing and dyeing wastewater using ozone microbubble

Owing to its widespread and persistent usage, methylene blue (MB) is an environmental substance, mostly found in the printing and dyeing industry that raises concerns in the environment recently by posing significant threat to human life and the ecosystem as a whole. Thus, there is the need to effectively manage and treat the wastewater from these industries before reaching to the available water sources. Ozonation treatment is very efficient in treating printing and dyeing wastewater (MB) and can be greatly improved by using micro-bubble technology. Microbubble dissolution is an effective way to improve the rate of ozone mass transfer. To discover these properties, a method was used to improve the mass transfer of ozone microbubbles, which was used to effectively treat simulated printing and dyeing wastewater. We investigated the effects of pH, water temperature, ozone flow, and other conditions on the dissolution and attenuation properties of ozone in methylene blue microbubble solutions. Treatment of simulated printing and dyeing wastewater (methylene blue) was investigated under various initial pH and ozone flow rates. A catalytic exhibition was performed towards the decolorization of methylene blue (MB) concentrations and the corresponding COD removal efficiency. Ozone depletion and pH levels played key roles in MB degradation. Under high pH level of 11.01, the rate of removal of COD was 93.5%. Ozone dosage also has direct effect on COD removal efficiency and decolorization. Higher ozone flow rates, 0.4 L/min and 0.5 L/min recorded more than 94% degradation of COD thus very effective and efficient. Also, ozone flow rates 0.3 L/min, 0.4 L/min and 0.5 L/min with initial pH, 7.03, 6.63 and 6.36 decreased to 3.43, 3.49 and 3.44 after reaction processes which clearly shows that with high ozone dosage, pH reduces considerably.

Removal of methylene blue from aqueous solution by ozone microbubbles

In this work, ozone microbubbles (OMBs) technique was used to remove methylene blue dye (MB) from water in a semi- batch reactor. The removal efficiency of methylene blue dye were investigated under various reaction conditions such as effect of initial solution pH, ozone generation rate, initial methylene blue dye concentration and determination of mass transfer coefficient. The removal of methylene blue by Ozonation microbubbles were very high at the acidic media and upon increasing ozone generation rate from 0.498 to 0.83 mg s−1, the removal efficiency dramatically increased from 8 to 98%.The overall rate of the oxidation reaction fitted well a second order kinetic model. The results demonstrated that ozone microbubbles were effective in terms of the elimination of methylene blue concentration and its complete mineralization.

A Study on Application of Ultrasonic Wave and Ozone Micro-Bubbles in Leafy Vegetables Washing

The demand for vegetable consumption is essential issue to serve citizens. Excessive protective chemical elimination which is applied advanced solutions brings high effects being investigated by domestic and international scientists. In this report, research team conducted and designed the vegetable washing machine integrated with the ultrasonic power and Ozone microbubbles to wash out plentiful protective chemicals attaching to surfaces of leafy vegetables. Followingly, using Taguchi method for four kinds of vegetables including salad, water spinach, Chinese cabbage, and mustard greens verifies the effectiveness of solutions. Vegetable samples are treated soaking pool making ultrasonic wave and Ozone microbubbles raging from 1.0ppm to 2.0ppm. The practical results demonstrated that the method using the ultrasonic power and Ozone microbubbles has high effects on eradicating protective chemical on leafy vegetables.

Treatment of High Concentration Acid Plasticizer Wastewater by Ozone Microbubble Oxidation

The large use of plasticizers in industry produced large amounts of wastewater. The treatment of industrial wastewater with advanced oxidation processes (AOPs) has attracted widespread interest from scientists in recent years. Comparing with several common AOPs such as activated persulfate, Fenton, UV, and H2O2, the ozone oxidation technology has the advantages of not introducing other chemical reagents, not bringing secondary pollution, lower energy consumption, safety, and non-flammability or explosion. Using the ozone microbubble process to treat high-concentration acidic plasticizer wastewater is in line with the concepts of green, energy-saving, and environment friendly. This work studied the changes of chemical oxygen demand (COD), pH, and dissolved oxygen (DO) in wastewater by adjusting the reaction time, system pressure, and reaction temperature, and revealed the best working conditions of ozone microbubble technology to treat plasticizer wastewater. The experiment shows that with the condition of the reaction time of 45 h, the pressure of 0.150 MPa, the ozone concentration of 100%, and the gas flow of 0.7 L/min, the dissolved oxygen (DO) of the wastewater increased from 3.8 to 4.5 mg/L, while the pH value increased from 3.23 to 7.54, and the COD removal rate reached up to 94.18%. This work discussed the mechanism of ozone microbubble technology to degrade plasticizer wastewater, and also confirmed that ozone microbubble technology can generate high hydroxyl radicals, even under acidic media. In addition, this technology does not require the addition of any additional chemical reagents and does not form a precipitate in the reaction to cause secondary pollution to the environment. Meanwhile, the water treatment costs of unit tons using this technology have also been analyzed. This technique has great practical application prospects in treating high concentration organic acid wastewater.

Investigation of Ozone Microbubbles for the Degradation of Methylene Orange Contaminated Wastewater

In the present study, semi – batch experiments were conducted to investigate the efficiency of ozone microbubbles (OMBs) in the treatment of aqueous dye solutions methylene orange under different reaction conditions such as effect of initial solution pH , ozone generation rate and initial MO-concentration. The results showed that the removal of MO by OMBs were very high at the acidic and alkaline media and upon increasing the generation rate of ozone from 0.498 to 0.83 mg/s, the removal efficiency dramatically increased from 75to 100% within 15 min. The rate of oxidation reaction followed a pseudo first- order kinetic model. The results demonstrated that OMBs is efficient in terms of the decline of methylene orange concentration and its total mineralization.

Microbubble ozonation of the antioxidant butylated hydroxytoluene: Degradation kinetics and toxicity reduction

Butylated hydroxytoluene (BHT) is recognized as a crucial pollutant in aquatic environments, but efforts to achieve its complete removal are without success. The aim of this study was to investigate the degradation efficiency of BHT in water using ozone microbubbles (OMB), coupled with toxicity change assessment at sub-lethal BHT concentrations (0.34, 0.45 and 0.90 μM) based on oxidative stress biomarkers in Daphnia magna. The efficiency of OMB on ozone gas mass transfer was assessed and the contribution of hydroxyl radicals (·OH) in the degradation of BHT was determined using p-chlorobenzoic acid (pCBA) probe compound and a ·OH radical scavenger (sodium carbonate, Na2CO3). The ozone gas mass transfer coefficient (kLa = 1.02 × 10−2 s−1) was much larger than the ozone self-decomposition rate (kd = 8 × 10−4 s−1) implying little influence of self-decomposing ozone in the volumetric ozone transfer during OMB generation. Generally, OMB improved ozone gas mass transfer (1.3–19-fold) relative to conventional ozone techniques, while indirect reaction of BHT with ·OH was dominant (82%) over the direct reaction with molecular ozone. Addition of 15, 25 and 35 mM Na2CO3 reduced BHT degradation by 30, 50 and 65%, respectively, indicating the significance of ·OH in the degradation of BHT. Increase in initial BHT concentration correspondingly reduced its removal rate by OMB possibly due to increase in metabolites produced during ozonation. Post BHT treatment exposure tests recorded significant (p < 0.05) reductions in oxidative stress (according to enzyme activities changes) in D. magna compared to pretreatment tests, demonstrating the effectiveness of OMB in detoxification of BHT. Overall, the results of the study indicate that OMB is extremely efficient in complete degradation of BHT in water and, consequently, significantly (p < 0.05) reducing its toxicity.

Comparative efficiency of three advanced oxidation processes for thiosalts oxidation in mine-impacted water

Grinding and flotation of sulfide-containing ores produce metastable, partially oxidized sulfur compounds known as thiosalts, which are notorious contributors to receiving water bodies’ toxicity by producing delayed acidity. Thus, the continuous optimization of thiosalts oxidation into sulfate is required before treated mine water is discharged into natural streams, as thiosalts oxidation slows down at low temperatures and in the absence of UV. With this aim, the present study evaluated the treatment of thiosalts at initial concentrations of 100 mg/L, 290 mg/L and 630 mg/L using three advanced oxidation processes (AOPs): (1)wet ferrates Fe(VI), 65 mg/L; (2)ozone microbubbles (O3-microbubbles), 75 g/h sparging rate; and (3)hydrogen peroxide (H2O2), 2:1 (H2O2:thiosalts) molar ratio, at 8 °C and 22 °C. All treatability tests were performed on synthetic effluents, while H2O2 efficiency was also assessed with a real effluent, a leachate of non-desulfurized tailings collected at a flotation plant. Results showed that O3-microbubbles gave better efficiency (99%) than wet Fe(VI) (82%) after 2 h of thiosulfate treatment. Similar trends were observed with synthetic and real effluents for treatment with H2O2. Efficient removal of thiosalts in the real effluent required several days of reaction at 8 °C (98%), whereas efficient removal at 22 °C (90%) was reached after 1 h of treatment. All three AOPs tested proved promising for thiosalts removal. The O3-microbubbles showed the best efficiency in terms of thiosalts removal and treatment time. Moreover, H2O2 allowed for better thiosulfate removal than wet Fe(VI), but proved inefficient at oxidizing other intermediate S species and required longer treatment time.

Low Environmental Impact Cleaning Technology with Ozone Micro-Bubbles Generated by a Venturi Tube

Cleaning technology is widely used to remove oil or resist from metal and semiconductor and soon. However, it causes high cost and severe environmental impacts because of the sewage disposal. Owing to strong oxidizing ability and self-decomposing power, ozone micro-bubbles generated by a Venturi tube was proposed. The purpose of this study is to research the capability of ozone micro-bubbles and improve the cleaning mechanism. In this study, we focus on the microbubble generator with a Venturi tube. We visualized the Venturi Tube by a high-speed camera to measure the bubble diameter. We also measure the shear stress near the test piece surface by using PIV. And by titration with Potassium iodide, ozonated water and ozone gas concentration are measured. Ozone gas is well dissolved after passing through the Venturi tube. Also, brass test pieces applied with cutting oil and latex resin are washed by using bubbly flow with ozone micro-bubbles. It has been confirmed that ozone micro-bubbles are able to clean the test pieces efficiently.

Growth response of hydroponic leaf lettuce and komatsuna to ozone microbubble treatment

Previously, we found that ozone microbubble (O3MB) treatments of 0.2 mg L−1 of dissolved ozone (DO3) are effective for sterilizing hydroponic solutions. However, there are few studies on cultivated plant growth responses to O3MB-treated hydroponic solutions. We investigated effects of different O3MB treatments in hydroponic solutions on the growth of leaf lettuce and komatsuna plants, and inhibiting factors for komatsuna growth. Fe concentrations in O3MB-treated hydroponic solutions decreased significantly compared with control solutions because of the precipitation of oxidized Fe. The growth of hydroponic lettuce treated with O3MB was equivalent to that of the control. However, the growth of komatsuna was suppressed with increasing DO3 concentrations. Leaf lettuce might avoid Fe deficiency by secreting riboflavin from roots. On the other hand, since komatsuna does not secrete riboflavin against Fe deficiency, Fe deficiency in hydroponic solutions might lead to growth suppression. We investigated the influence of added Fe in hydroponic solutions treated with O3MB on the growth of komatsuna. No growth differences for komatsuna were observed between Fe-added hydroponic solutions treated with O3MB and the control solution. Growth suppression of O3MB-treated hydroponic komatsuna may be avoidable by Fe addition.

Decomposition of 2-Propanol in the Liquid Phase Using a Photocatalyst Immobilized on Nonwoven Fabric and Ozone Microbubbles

2-Propanol (IPA) is a highly water-soluble volatile organic compound that is used in the cleaning and drying processes during semiconductor fabrication. IPA is also used as a disinfectant in the pharmacy field. Water scrubber processing is one of the methods used for IPA collection. However, water scrubbing requires wastewater treatment. In this study, we propose a decomposition system for IPA in the liquid phase based on a TiO2 photocatalyst immobilized on nonwoven fabric (TiO2 nonwoven fabric) and ozone microbubbles (MBs). The thick nonwoven fabric with immobilized TiO2 exhibits a higher IPA removal rate than that exhibited by the pleated fabric. IPA decomposes to produce acetone, which can be further decomposed and possibly undergo mineralization. The entire water tank can be supplied with ozone by introducing the MB-forming ozone, which considerably affects the decomposition of IPA. The efficient decomposition of IPA was achieved by combining ozone MBs, TiO2 nonwoven fabric, and ultraviolet irradiation, presumably because the photocatalyst promotes the mineralization of the decomposition product. Thus, the OH radicals from the O3 MBs competitively captured in the decomposition product strongly promote the decomposition of IPA, enhancing the IPA decomposition rate.

Efficiency of ozone microbubbles for ammonia removal from mine effluents

Several physical, chemical, and biological technologies efficiently treat ammonia nitrogen (NH3-N). However, cold temperatures and mixes of contaminants limit NH3-N removal efficiency. This study evaluated the ozone microbubbles efficiency for NH3-N removal from synthetic and five actual mine effluents. Testing was initially conducted in batch mode. Then, to confirm treatment feasibility, tests with continuous flow were performed with one synthetic and one real effluent. Results showed that the parameters of the water to be treated have significant influence on treatment efficiency. The presence of cyanides, cyanate, thiocyanate, and metals adversely influenced treatment performance. The NH3-N removal efficiency ranged from 27.8 to 99.3%. Continuous flow testing confirmed the feasibility of large-scale treatment as 99.1% of NH3-N was treated at a flow rate of 1.1 L/min over a treatment period of 570 min. Final polishing steps removed the pink color from the water after ozone microbubbles treatment, resulting in satisfactory quality of treated water.

EFFECT OF OZONE MICROBUBBLES WITH VARIOUS TEMPERATURES ON THE CHLORPYRIFOS INSECTICIDE REMOVAL IN TANGERINE CV. SAI NAM PHUENG

Chlorpyrifos, a type of organophosphate insecticide, is widely used to destroy pests in the tangerine orchard to reduce the loss and maintain the quality of fruit. Consequently, the application of insecticides during production leads to the insecticide residues problem in tangerine that can be dangerous to human health. This study investigated the effect of ozone microbubbles (OMBs) on the removal of chlorpyrifos residues in the fruit. Tangerines were sprayed with chlorpyrifos solution at a concentration of 10 minutes. Then, they were treated with OMBs at different temperatures (15, 20 and 25 oC) for various exposing times (0, 10, 20, 30, 40, 50 and 60 minutes). Removal percentage of chlorpyrifos residues in tangerines was determined by gas chromatography-flame photometric detector (GC-FPD). The results showed that chlorpyrifos residues in tangerines were decreased at lower water temperature, especially at 15 oC resulting in the removal up to 81% after treating with OMBs for 30 minutes when compared to control (distilled water). After that, the fruits were stored at 25 oC for 7 days to determine quality changes. The percentage of weight loss, total soluble solids (TSS), titratable acidity (TA), disease incidence and ascorbic acid content in all treatments were not affected by OMBs. These results demonstrate that OMBs treatment at 15 oC is the most effective treatment for removing chlorpyrifos residues in tangerine and have no effects on the fruit quality.