Integration Of Ozonation Research Articles

Effect of Ozone assisted hydro cooling system on cooling characteristics, microbial inactivation, and quality of fresh produce (amla and tomato)

The ozone assisted hydro cooling (OAHC) process is introduced for simultaneous disinfection and pre-cooling of fresh produce. This study was conducted to examine the effect of different ozone concentrations (0.3, 0.7, and 1.5 ppm) on hydrocooling process and postharvest qualities of amla and tomato. The investigation included post-harvest qualities characteristics assessment between OAHC and cold room cooling. It was observed that the integration of ozone into hydrocooled water did not negatively impact cooling kinetics, while an ozone concentration of 1.5 ppm reduced E. coli count by 2.4 and 3.1 log cycles from tomato and amla, respectively. SEM analysis revealed no significant changes in amla and tomato pericarp microstructure during the OAHC process. In addition, OAHC-treated amla and tomato demonstrated lower weight loss, ascorbic acid, and higher phenolic compounds. The study outcomes concluded that OAHC technology did not adversely affect the cooling process and quality characteristics during the hydrocooling process and preserved the quality of fresh produce during storage.

Ozonation degradation of wastewater using rotational hydrodynamic cavitation reactor with a conical rotor

ABSTRACT Water pollution caused by an abusive discharge of dye-containing wastewater leads to serious ecological risks. Conventional wastewater treatment methods have shortcomings of incomplete degradation, long-time treatment and secondary pollution. For the first time, a rotational hydrodynamic cavitation reactor (RHCR) equipped with a conical rotor has been designed to enhance the ozonation process for effective degradation of pollutants. The effects of rotational speed, discharge voltage, gas flow rate, liquid flow rate and initial pH on methylene blue (MB) degradation were deeply investigated. The optimised conditions were initial pH = 9, rotational speed = 1800 rpm, discharge voltage = 9.3 kV, gas flow rate = 60 mL/min and liquid flow rate = 80 mL/min. With the integration of ozonation and cavitation in RHCR, the MB degradation efficiency reached 95.2%, which was 15.6% higher than that of the individual ozonation method. The degradation process was proven to track the first-order kinetic model, with the reaction rate and synergy index were 0.232 min−1 and 1.78, respectively. Through the quenching experiments, it can be confirmed that the contribution proportion of hydroxyl radical during degradation was increased by 8.7% due to the enhancement of cavitation. A required energy consumption of 74.7 kWh/order/m3 and a total expense of 8.7 $/m3 were calculated. The energy consumption of the RHCR was approximately 80% lower than that of the recently reported degradation system combining ozonation and cavitation, with total expense reduced by 52%. The findings of this work provide a new water treatment method and offered theoretical references for the design of RHCR.

Integration of Ozonation with Biodegradation for Dye Wastewater Treatment

Integration of Ozonation with Biodegradation for Dye Wastewater Treatment

Integration of ozone with co-immobilized microalgae-activated sludge bacterial symbiosis for efficient on-site treatment of meat processing wastewater

Direct discharge of high concentration meat processing wastewater (MPW) into municipal sewage system will cause serious shock loading and reduce wastewater treatment efficiency, thus, efficient on-site pretreatment is usually required. Purpose of this study is to integrate ozone with microalgal biotreatment to achieve effective removal of both organic compounds and nutrients with one-step biodegradation and obtain high quality effluent dischargeable to municipal sewage system. Results showed that ozone pretreatment removed 35.0–90.2% color and inactivated 1.8–4.7 log CFU/mL bacteria in MPW. In post biotreatment using microalgae co-immobilized with activated sludge (ACS) bacteria, bacterial growth in ozone pretreated wastewater (7.1–8.1 log CFU/mL) were higher than non-pretreated control (6.0 log CFU/mL) due to enhanced biodegradability of wastewater pollutants. Algal biomass growth in wastewater pretreated with 0.5 (2489.3 mg/L) and 1 (2582.0 mg/L) minute's ozonation were improved and higher than control (2297.1 mg/L). Ozone pretreatment significantly improved nutrients removal. Following ozone pretreatment of 0.5 min, microalgal biotreatment removed 60.1% soluble chemical oxygen demand (sCOD), 79.5% total nitrogen (TN) and 91.9% total phosphate (PO43−) which were higher than control (34.4% sCOD, 63.4% TN, 77.6% total PO43−). Treated effluent contained 342.3 mg/L sCOD, 28.8 mg/L TN, 9.9 mg/L total PO43− and could be discharged into municipal sewage system. However, excessive ozone pretreatment displayed adverse impact on algal growth and sCOD removal. Therefore, integration of 0.5 min's ozone pretreatment with microalgae-based biotreatment is an efficient on-site treatment to simultaneously remove organic compounds and nutrients with one-step biodegradation.

Integration of ozone, UV/H2O2 and GAC in a multi-barrier treatment for secondary effluent polishing: Reuse parameters and micropollutants removal

Current studies tend to combine different advanced treatment technologies to reduce costs and increase efficiency. The objective of this work was to assess the combination of ozonation and UV/H2O2 with activated carbon adsorption for the removal of effluent quality parameters and micropollutants from secondary effluent samples. The experiments were carried out using the following configurations: O3 + GAC + O3 (1); O3 + GAC + UV/H2O2 (2); UV/H2O2 + GAC + O3 (3); UV/H2O2 + GAC + UV/H2O2 (4). Configurations 1, 3 and 4 were the most efficient for organic matter removal, while configuration 1 had the lowest cost on laboratory scale. An additional ultra-filtration membrane unit (UF) was tested at the end of configuration 1, which was optimized in terms of ozone doses for the removal of three organophosphate micropollutants in ultrapure water (TNBP, TCIPP and TPHP at 10 μgL−1). The best cost-effective configuration of this treatment train was the one using 1 mg L−1 of ozone before and after GAC, which achieved around 100% of micropollutants abatement. The role of each treatment to the final micropollutant removal was also discussed, being the first ozone treatment responsible for about 15% removal of the mixture of contaminants, while GAC was responsible for an additional 80% removal. The complete treatment train reached almost 100% of contaminants removal (under detection limit of the method), as well as added security to the system. The achieved results were also compared to international reuse legislations, proving that the combination of O3 and GAC was an interesting option to achieve enough quality for some reuse purposes.

Integration of ozonation and an anaerobic expanded granular sludge bed reactor for micropollutant removal from sewage.

Conventional sewage treatment systems are generally not designed to remove micropollutants, requiring the development of new technologies, such as the combination of biological processes with advanced oxidative processes. The configuration of an anaerobic expanded granular sludge bed (EGSB) reactor stands out for its use of granular biomass and high sludge bed expansion. Ozonation is an advanced oxidative process that stands out as one of the most promising technologies for the degradation of micropollutants. Thus, the present work aimed to evaluate the removal of drugs through the application of ozonation as a polishing process for the effluent of an EGSB reactor that was fed with synthetic sewage. Ozonation was shown to be efficient in the degradation of these compounds, reaching removals above 90%. It was found that the degradation profile of each drug varied according to its chemical structure since some drugs are more susceptible to oxidation than others and since the concentrations of pharmaceuticals are also related to their removal. Moreover, the assessment of risks to the environment and human health confirmed the need to assess the best scenario for risk reduction considering all drugs, since even with almost complete removal of some compounds, the effluents still showed toxicity. Thus, the high removal efficiencies found for the evaluated micropollutants showed that this technique has the potential to be used to improve the quality of biological reactor effluents or even to be combined in effluent reuse systems.

The sustainable recovery of the organic fraction of municipal solid waste by integrated ozonation and anaerobic digestion

The organic fraction of municipal solid waste is commonly handled via biological processes, which enable the production of materials with potential fertilizer properties. When the biological process occurs under anaerobic conditions, the recovery of energy from biogas is also obtained. However, the sustainable recovery of organic solid waste implies the effective utilization of the biological treatment products, namely compost and digestate, which is often limited by the presence of organic contaminants. They enter the biological processes along with the organic waste and, due to their recalcitrance to the biodegradation, end up in either compost or digestate, posing the issue of their safe use on soil. The present study proposes ozonation as a possible strategy to reduce the presence of organic contaminants in the digestate originating from the organic fraction of municipal solid waste. In this view, digestate samples were collected from full-scale reactors operated at hydraulic retention time of 11 and 41 days and ozonated at 0.11 and 0.16 gO3/gTS. Experimental results, including the evaluation of the eco-toxicological potential of differently treated substrates, showed that the integration of ozone and anaerobic digestion can be pursued for the sustainable recovery of organic solid waste, but the identification of the combined process lay-out requires the evaluation of the digestate biological stabilization level.

Integration of Ozonation and Biological Treatment of Industrial Wastewater From Dyehouse

ABSTRACTThe aim of the research was to improve the treatment technology of wastewater from dyehouse using ozonation and biological processes. The various combinations of the processes were examined. Ozonation was performed in two reactors of working volume 1 dm3 (stirred cell) and 20 dm3 (bubble column), while biodegradation was conducted in sequence batch reactors (SBR 1.5 dm3) and horizontal continuous flow bioreactor (HCFB, 12 dm3). The highest removal of organic carbon content (COD–72%, TOC–78%) was obtained in the 3-steps experiment: biodegradation plus ozonation plus biodegradation, however, for economic reasons a sequence: biological treatment plus ozonation was selected as the mostly advisable one. The developed method allows closing of process water in the textile factories.

Evaluation of a Recirculating Dipper Well Combined with Ozone Sanitizer for Control of Foodborne Pathogens in Food Service Operations

In the retail food service industry, small countertop sinks, or dipper wells, are utilized to rinse and store serving utensils between uses. These dipper wells are designed to operate under a constant flow of water, which serves both to prevent the accumulation of microorganisms and to aid in the cleanliness of the dipper well itself. Here, a recirculating dipper well ozone sanitation system (DWOSS) was evaluated for the control and inactivation of Escherichia coli , Listeria innocua , PRD1 bacteriophage, and Staphylococcus aureus present on a stainless steel disher. In a low ozone (O3) demand medium, the DWOSS achieved over a 5-log reduction for E. coli , L. innocua , and PRD1 at 30 s when exposed to 0.45 to 0.55 ppm of residual O3. A greater than 5-log total CFU reduction was achieved for S. aureus at a 600-s exposure time and 0.50 ppm of residual O3. When evaluated in the presence of high O3 demand medium (10% skim milk), the DWOSS performed significantly better (P < 0.05) for all microbe-exposure time combinations compared with a conventional dipper well with respect to the reduction of microbes on the stainless steel disher. For example, at 30 s, the DWOSS achieved 4.37, 2.48, 1.38, and 1.31 greater log (CFU or PFU) reduction of E. coli , L. innocua , PRD1, and S. aureus , respectively, than a conventional dipper well. In addition, the DWOSS was evaluated under two neglect scenarios to determine its ability to control microbes in 10% skim milk medium on the stainless steel disher and within the dipper well basin itself over an extended period of use (2 h of use per day over 5 days). Considering the efficacy of the DWOSS unit against the microbes evaluated here, the integration of ozone into a dipper well could be a potential critical control point to reduce the incidence of microbial contamination during retail food service. To our knowledge, a dipper well with a cleaning-in-place sanitizing system is not currently available for use in the food service industry; and, thus, this is the first study to evaluate the efficacy of a cleaning-in-place dipper well.

Integration of ozonation and sonication with hydrogen peroxide and persulfate oxidation for polychlorinated biphenyls-contaminated soil treatment

Polychlorinated biphenyls (PCBs) are persistent organic contaminants and are known for their strong sorption to soil due to high hydrophobicity. A combination of either ozone or ultrasound with hydrogen peroxide or persulfate was applied to soil contaminated with PCB-containing electrical insulating oil, Clophen A30. Sole ozonation of PCB-contaminated soil resulted in the degradation of 50% of PCBs in 300min treatment. A substantial retardation in PCB degradation was observed after 120min ozonation, with only a 6% degradation in the following 180min. Compared with ozone or sole persulfate, the combined application of ozone with hydrogen peroxide or persulfate did not result in a higher degradation efficacy, thus making the processes integration useless. Process integration, achieved by the joint application of ultrasound and oxidizing chemicals in moderate doses, could be a promising option for the treatment of contaminated soil containing highly sorbed hydrophobic organic pollutants and thereby resulting in an improved efficiency for PCB degradation. Contrary to ozone-based treatment processes, prolonging the treatment time of both sonication and the chemical treatment process, as well as increasing the chemical dosage, favored the improved degradation. Although the energy required for 0.5 h of soil sonication was higher than that for ozonation, sonication can still be effectively integrated into the chemical oxidation process.

Integration of ozone and solar TiO2-photocatalytic oxidation for the degradation of selected pharmaceutical compounds in water and wastewater

The degradation of a mixture of four pharmaceutical compounds (atenolol, hydrochlorothiazide, ofloxacin and trimethoprim) in distilled water and in a synthetic solution simulating a typical secondary effluent from a municipal wastewater treatment plant by ozonation, solar TiO2-photocatalytic oxidation and a sequence of both methods has been investigated. Degradation by ozone led to the complete removal of the selected emerging compounds (EC) but an accumulation of ozonation by-products (e.g., phenolic intermediates and carboxylic acids) in solution was observed. The presence of ozone-consuming substances in the synthetic effluent had not a negative impact on the removal of the pharmaceuticals but on their mineralization (TOC removal <8%). By photocatalytic oxidation, the pharmaceutical compounds were completely removed with UVA radiation doses lower than 0.3kJ per mg EC while about 70% TOC conversion was achieved with a UVA radiation dose of 1kJ per mg EC. The presence of organic and inorganic matter in the secondary effluent had a negative impact on the mineralization of pharmaceuticals. Thus, initial TOC removal rate was five times lower when treating the pharmaceuticals in the synthetic effluent compared to distilled water. The application of a sequential ozone – TiO2 solar photocatalytic oxidation treatment allowed complete removal of pharmaceuticals by ozonation and further mineralization of ozonation by-products by the photocatalytic treatment.

Removal of emergent contaminants: Integration of ozone and photocatalysis

A mixture of nine pharmaceuticals has been treated by means of the systems: UV-B(313 nm), O(3), UV-B(313 nm) + TiO(2), O(3) + UV-B(313 nm), and O(3) + UV-B(313 nm)+TiO(2). Simple photolytic or ozonation processes lead to a deficient total organic carbon (TOC) elimination after 120 min of exposure (25 and 30% conversions, respectively). Addition of a photocatalyst such as titanium dioxide significantly enhanced the mineralization degree, a 60% TOC conversion was obtained. A TiO(2) load optimum around 0.25 g L(-1) was observed. No loss in photoactivity was experienced after 2 reuses. Due to ozone photodegradation, the combination of ozone and radiation increased the generation of hydroxyl radicals. As a consequence, TOC removal was increased to a value in the proximity of 85%. The most complex system, O(3) + UV-B(313 nm) + TiO(2), achieved the highest TOC abatement (95%). Use of ozone in photocatalytic processes involves an increase in hydroxyl radical generation.

Catalytic oxidation of highly concentrated real industrial wastewater by integrated ozone and activated carbon

Abstract Integration of ozone and granular activated carbon (GAC) was applied to treat highly concentrated real wastewater from chemical industry. The results revealed that the integrated process had more advantages than the individual ozonation and GAC adsorption. The integrated process enhanced COD removal, increased ozone utilization and avoided frequent GAC regeneration. The pH value was found to exert a great effect on COD removal; a positive effect on COD removal was more pronounced at basic conditions than at acidic conditions. Furthermore, there were some differences in reaction mechanisms at different pH conditions, as confirmed by FTIR and SEM analysis. At the acidic conditions, the primary reaction mechanism was adsorption–ozonation regeneration, while at the basic conditions, GAC adsorption ability was restrained, and the primary mechanism was catalytic oxidation.

Biodegradability Improvement of Aqueous 2,4-Dichlorophenol And Nitrobenzene Solutions By Means of Single Ozonation

The possibility of the integration of ozonation and biological processes as an economical way to treat biorecalcitrant organic compounds such as nitrobenzene and 2,4-dichlorophenol was investigated. In the pre-treatment step, stoichiometric coefficients and pseudo first-order kinetic constants were obtained. Biodegradability was monitored throughout the ozonation step, in order to evaluate the optimum ozone doses. The low TOC reduction after these ozone doses allowed much of the organic carbon to be removed in the biological stage. In the case of 2,4-dichlorophenol, the biodegradability improvement was checked in an aerobic bioreactor. By means of the combined ozonation-biological oxidation, up to 80% of the initial organic content was removed. Results presented in this study show the feasibility of using the combination of ozone and conventional biological treatments to treat wastewaters containing these pollutants.

Integration of Ozonation and an Anaerobic Sequencing Batch Reactor (AnSBR) for the Treatment of Cherry Stillage

Cherry stillage is a high strength organic wastewater arising from the manufacture of alcoholic products by distillation of fermented cherries. It is made up of biorefractory polyphenols in addition to readily biodegradable organic matter. An anaerobic sequencing batch reactor (AnSBR) was used to treat cherry stillage at influent COD ranging from 5 to 50 g/L. Different cycle times were selected to test biomass organic loading rates (OLR(B)), from 0.3 to 1.2 g COD/g VSS.d. COD and TOC efficiency removals higher than 80% were achieved at influent COD up to 28.5 g/L but minimum OLR(B) tested. However, as a result of the temporary inhibition of acetogens and methanogens, volatile fatty acids (VFA) noticeably accumulated and methane production came to a transient standstill when operating at influent COD higher than 10 g/L. At these conditions, the AnSBR showed signs of instability and could not operate efficiently at OLR(B) higher than 0.3 g COD/g VSS.d. A feasible explanation for this inhibition is the presence of toxic polyphenols in cherry stillage. Thus, an ozonation step prior to the AnSBR was observed to be useful, since more than 75% of polyphenols could be removed by ozone. The integrated process was shown to be a suitable treatment technology as the following advantages compared to the single AnSBR treatment were observed: greater polyphenols and color removals, higher COD and TOC removal rates thus enabling the process to effectively operate at higher OLR, higher degree of biomethanation, and good stability with less risk of acidification.

Oxidation of aqueous phenol by ozone and peroxidase

Aqueous phenol was ozonated for the first time at pH over 12. Results obtained under conditions favoring rapid generation of radicals completely eliminated the possibility deduced from the absorption theory that the indirect radical reaction might be one of the reaction pathways. Meanwhile, it was found in this study that the apparent first-order rate constant of phenol ozonation decreased logarithmically with increasing initial phenol concentration. On the other hand, despite the phenomenological resemblance between the two oxidation processes (the removal of aqueous phenol by ozone and horseradish peroxidase (HRP)), the mechanisms of the two processes were proved to be quite different. Results of this study also indicate that the integration of ozone and HRP did not improve the efficiency of phenol removal.

Evaluation of Ozone for Cryptosporidium Inactivation and Atrazine Oxidation in a Lime Softening Plant

This case study evaluates the integration of ozone in a softening plant with emphasis on the feasibility of high pH ozonation. The softening plant in Jefferson City, Missouri, treats Missouri River water characterized by high hardness, TOC of up to 8.0 mg/L, and occurrences of atrazine at concentrations up to 20 μg/L. As part of the predesign effort for rehabilitation of the existing WTP, ozone was evaluated to achieve current and anticipated future disinfection requirements, as well as atrazine removal. Testing using a continuous flow bench scale unit was conducted to evaluate ozone for 2-log Cryptosporidium inactivation and to oxidize 10 to 14 μ/L of atrazine. Because of the high CT required for 2-log Cryptosporidium inactivation, it was found that practicing an AOP was not necessary to reduce the atrazine level to below the current maximum contaminant level (MCL) of 3 μg/L. In this case, the long term disinfection requirements for Cryptosporidium likely will drive the ozone system design criteria despite the high levels of atrazine occurring in the raw water supply.

Methods in aquatic bacteriology Austin, B 1 vol. (15,5?sx23,5 cm), 425 + xix pages. John Wiley &amp; Sons, New York, Chichester, 1988.

Aqueous phenol was ozonated for the first time at pH over 12. Results obtained under conditions favoring rapid generation of radicals completely eliminated the possibility deduced from the absorption theory that the indirect radical reaction might be one of the reaction pathways. Meanwhile, it was found in this study that the apparent first-order rate constant of phenol ozonation decreased logarithmically with increasing initial phenol concentration. On the other hand, despite the phenomenological resemblance between the two oxidation processes (the removal of aqueous phenol by ozone and horseradish peroxidase (HRP)), the mechanisms of the two processes were proved to be quite different. Results of this study also indicate that the integration of ozone and HRP did not improve the efficiency of phenol removal.