Impact of Ozonated Water on the Quality and Shelf-life of Fresh Citrus Fruit,Stone Fruit,and Table Grapes

Spores of fungi that cause postharvest decay of fresh fruit die rapidly in ozonated water. We determined the impact of sporocidal or higher O₃ doses on fruit shelf-life and quality. Green mold and sour rot on citrus fruit, caused by Penicillium digitatum and Geotrichum citri-aurantii, respectively, were not reduced by 20 min immersion in 10 ppm O₃. These fungi infect through wounds; their spores were placed in shallow wounds (l mm wide by 2 mm deep) 24 hr before treatment. On five peach varieties, the average natural incidence of brown rot, caused by Monilinia fructicola, was reduced from 10.9 to 5.4% by 1 min immersion in 1.5 ppm O₃. A treatment of 15 min with 5 ppm O₃ further reduced decay to 1.7%, but consistent control of brown rot was associated only with this severe treatment and it caused shallow pits on the fruit. Brown rot caused by spores placed in wounds before treatment was not controlled. Immersion for 1 or 5 min in 5 ppm O₃ reduced natural aerobic bacteria populations by 1.1 and 1.6 log₁₀ units, respectively, and yeast and filamentous fungal populations by 0.7 and 1.3 log₁₀ units, respectively. Spores of Botrytis cinerea, cause of gray mold, were sprayed on table grape clusters, the clusters were dried, and then immersed for 1 to 6 min in 10 ppm O₃. In two tests, immersion for 1 min in O₃ reduced gray mold from 35% among untreated grapes to about 10%, while in two other tests the incidence was only reduced from 35 to 26%. Minor injury to the rachis of grape clusters occurred at high O₃ rates. Immersion in ozonated water did not control postharvest decay of citrus fruit, injured peaches and nectarines at doses that reliably controlled decay, and on table grapes control was irregular and caused minor rachis injury at high rates.     

Disinfection of recycled red‐meat‐processing wastewater by ozone

Ozonation of a real red‐meat‐processing wastewater was conducted in a semi‐batch reactor to explore the possibility of the water reuse. The experimental results revealed that ozone was very effective in disinfection of the red‐meat‐processing wastewater. After 8 min of ozonation with an applied ozone dose of 23.09 mg min^?1 liter^?1 of wastewater, 99% of aerobic bacteria, total coliforms and Escherichia coli were inactivated. Empirical models were developed to predict the microbial inactivation efficacy of ozone from the CT values for the real red‐meat‐processing wastewater. A correlation was also derived to estimate the CT values from the applied ozone dose and the ozone contact time. The results also revealed that under the ozonation condition for 99% inactivation of aerobic bacteria, total coliforms and E coli, the decrease in the chemical oxygen demand and the 5‐day biological oxygen demand of the wastewater were 10.7% and 23.6%, respectively. However, ozonation under this condition neither improved the light transmission nor reduced the total suspended solids (TSS) despite of the decolorization of the wastewater after ozonation. Copyright © 2005 Society of Chemical Industry     

Hydroxyethyl cellulose-based indicator labels to track freshness of anchovy (Engraulis encrasicolus)

In this study, it was aimed to develop a freshness indicator label that changes color with spoilage of fish. Hydroxyethyl cellulose-based indicator labels were prepared using two different mixed indicator (bromothymol blue/phenol red, cresol red/thymol blue) formulations. The functionality of prepared indicator labels was tested on anchovy (Engraulis encrasicolus) stored at 2°C and 10°C. Changes in total mesophilic aerobic bacteria, Pseudomonas spp., total yeast and mold counts, and total volatile basic nitrogen (TVB-N) contents of anchovy during storage were examined. Color changes of prepared indicator films were measured by a colorimeter. Correlation between color changes of indicator labels with microorganism growth and content of TVB-N was investigated. It is concluded that developed indicator labels change color with spoilage of anchovy and can be used as freshness indicator in fish industry.     

Enhancement in mineralization of some natural refractory organic compounds by ozonation–aerobic biodegradation

Two schemes, the first involving ozonation followed by final aerobic biodegradation (phase I experiments), and the second involving initial aerobic biodegradation, followed by ozonation and subsequent final aerobic biodegradation (phase II experiments), were examined for enhanced mineralization of refractory model compounds, viz. gallic acid, tannin and lignin. In all cases, and irrespective of the applied scheme, chemical oxygen demand (COD), total organic carbon (TOC), COD/TOC ratio, and specific UV absorbance at 280 nm attributed to the model compounds decreased with application of increasing ozone dose. The residual organic matter remaining after ozonation exhibited enhanced aerobic biodegradability in all cases. Further, in all cases and irrespective of the applied scheme, the overall amount of COD and TOC removed through the combination of ozonation and biodegradation processes increased with increase in ozone dose for all three model compounds, and more than 90% COD removal could be achieved with an ozone dose of 3 mg ozone absorbed per mg initial TOC, as compared with approximately 40% COD removal when no ozone was applied. Treatment by the first scheme resulted in the fraction of starting COD removed through biodegradation decreasing with increase in ozone dose in all cases, while this fraction increased or remained constant during treatment using the second scheme. In the case of tannin and lignin, similar overall COD removal could be achieved at lower ozone doses using scheme II. Due to incorporation of the initial aerobic biodegradation step in scheme II, the ozone requirement for additional mineralization, ie mineralization over and above that achieved by aerobic biodegradation, was also lower than that in scheme I. Copyright © 2005 Society of Chemical Industry     

Membrane Fouling in the Reclamation of Secondary Effluent with an Ozone-Membrane Hybrid System

Abstract

The current research is a pilot scale study on membrane fouling in an ozone-ceramic membrane hybrid system, aiming at the reclamation of secondary effluent which contains abundant organic substances and bacteria. Compared with the microfiltration process with 30 mg O₃/L feed, the microfiltration without ozone sustained for a longer period of time and produced greater filtrate volume, while all other conditions were kept constant. The results of size exclusive chromatography (SEC) show that the number of large molecules increases after ozonation; this part of organic molecules may contribute more to 0.1 µm membrane fouling. Other evidence proves that ozone brings about the lysis of bacteria. This may account for the increase in the number of large organic molecules after ozonation.     

Microbiological quality of vanilla ice cream manufactured in Caracas, Venezuela

A total of 122 samples of vanilla ice cream, the base product used for all flavors, prepared by eight different large firms at the Metropolitan Area of Caracas, Venezuela, were analyzed for aerobic mesophilic and psicrophilic bacteria, Staphylococcus aureus, Enterobacteriaceae, and Filamentous fungi. Findings revealed that within the sampling, 56.6% complied with the international standards proposed for aerobic mesophilic bacteria, 68% for Staphylococcus aureus, and 23% for Enterobacteriaceae. Three serotypes of enteropathogenic Escherichia coli, one of Salmonella, and one of Shigella were found. Ten genera of Filamentous fungi were isolated and identified.     

Modeling and experimental of mould disinfestation of soybean silos with ozone

ABSTRACT

This study aimed to develop and validate a mathematical model for predicting ozone propagation and distribution in a bench-scale storage silo of soybean and link the model results to its application as an antifungal. The reduction of potentially toxigenic fungi found in soybeans was also evaluated after the ozone treatment. Experimental validation consisted of the ozone application and concentration (ozone) monitoring at the experimental silo outlet. The soybean grains were analyzed prior to and after ozone treatment from different portions of the silo to evaluate the antifungal activity. After 30 minutes of ozone exposure, there was an 88% reduction in the amount of fungi present at the lower section, reaching total elimination with longer exposure times. Fusarium was the main genus found, and it was significantly reduced even with the shortest exposure (30 min). The results of the ozone propagation in soybeans will be useful to better understand its behavior within silos, in order for the elimination of biological contaminations to occur. The model showed ozone spread through the silo, and this treatment showed to be an effective alternative to control against potentially toxigenic fungi found in soybeans.     

Systematic Analysis of the Biochemical Characteristics of Activated Sludge During Ozonation for Lowering of Biomass Production

Properties of activated sludge during ozonation were analyzed. The structure and surface characteristics altered with the increase of ozone dosage. At low ozone dosage, the floc structure was completely dismantled. Floc fragments reformed through reflocculation at an ozone dosage greater than 0.20 g O₃·g^?1 mixed liquor suspended solids (MLSS). Inactivation of microorganisms in the activated sludge mixture was caused by ozonation. Microbial growth decreased by up to 65% compared to the control. Simultaneously, 92.5% of nucleotide and 97.4% of protein in microbial cells of the sludge were released. Organic substance, nitrogen and phosphorus were released from the sludge during the ozonation process. The initial value of soluble chemical oxygen demand (SCOD) was 72 mg·L^?1. When the ozone dosage was 0.12 g O₃·g^?1 MLSS, the value of SCOD rapidly reached 925 mg·L^?1, increased by almost 12-fold. Simultaneously, 54.7% of MLSS was reduced. The composition of MLSS was changed, indicating that the inner water of cells and volatile organic substance decreased during the ozonation process.     

Performance evaluation of ozonation and an ozone/hydrogen peroxide process toward development of a new sewage treatment process—Focusing on organic compounds and emerging contaminants

Performance of ozonation and an ozone/hydrogen peroxide process under a new concept centering on ozonation and/or ozone/hydrogen peroxide processes in sewage treatment processes comprising only physical and chemical processes are discussed, with focus on the removal of matrix organic compounds and emerging contaminants. Matrix organic compounds of filtrated primary sewage effluents were removed to as low as 3.2 mgC/L in the ozone/hydrogen peroxide process at an ozone consumption of around 400 mg/L. Linear relationships between ozone consumption and removal amounts of organic compounds were observed, in which the amounts of ozone required to remove 1 mg of organic carbon were 9.5 and 8.3 mg (2.4 and 2.1 mol-O₃/mol-C) in ozonation and the ozone/hydrogen peroxide process, respectively. Ratios of hydroxyl radical exposure to ozone exposure were in the order of 10^–9 to 10^–8 for ozonation and 10^–7 to 10^–6 for the ozone/hydrogen peroxide process. Experiments and a kinetic evaluation showed that ozonation and/or the ozone/hydrogen peroxide process have high elimination capability for emerging contaminants, even in primary sewage effluent with the thorough removal of matrix organic compounds. Newly found reaction phenomena, the temporal increase and decrease of dissolved ozone and accumulation of hydrogen peroxide in the early stage of oxidation with the continuous feeding of hydrogen peroxide, were presented. Possible reaction mechanisms are also discussed.     

Seawater ozonation: effects of seawater parameters on oxidant loading rates,residual toxicity,and total residual oxidants/by-products reduction during storage time

The efficacy of ozonation in different seawater conditions provides an improvement in the water quality and promotes the increment of dissolved oxygen. By-products (bromine, bromate, and bromoform) formation is directly proportional to the ozonation time. Ozone-produced oxidants remain toxic in both closed and dark containers for at least 4 days; however, during long storage period (35 days) in dark and cold conditions, these residual oxidants decrease slowly. These results have practical implications for both the installation of ozone systems on ships ballast water or for recirculating aquaculture system for inactivating undesirable organisms present in seawater.     

Effects of Ozone Treatment on Microbiological Quality and Physicochemical Properties of Turkey Breast Meat

ABSTRACT

The effects of ozone treatment (1 × 10^?2 kg m^?3, for up to 8 h) on quality parameters of turkey meat were investigated. Ozone was effective in inactivating microorganisms. Approximately 2.9, 2.3 and 1.9 log reductions were achieved in the counts of total aerobic mesophilic bacteria, Enterobacteriaceae and yeast-mold, respectively. Ozone caused significant changes in carbonyl contents, thiobarbituric acid reactive substances, color and pH values of the samples. Water holding capacity and cooking yield of treated samples increased significantly (p < .05). This is the first report demonstrating that quality parameters of turkey breast meat are markedly affected by ozone treatment.     

Degradation of Carbamazepine by Photo-assisted Ozonation: Influence of Wavelength and Intensity of Radiation

This article presents the results of an investigation into the function of UV in a photo-assisted ozonation process for treatment of carbamazepine (CBZ) in treated domestic wastewaters. Experiments were conducted on synthetic spiked water and secondary treated municipal wastewater. Degradation of CBZ was studied for various combination of O₃ dosage ranging from 4.8 to 14.4 mg/h and UV intensities with varying intensity and wavelength (UVC: λ = 254 nm and UVA: 352 nm). In synthetic spiked water, CBZ was degraded to below detectable limits within 0.5 min for ozone dose of 14.4 mg/h. The rate of degradation of CBZ increased exponentially with increase in ozone dose following a zero-order rate at each dose level. The degradation rate of CBZ in wastewater was slower compared to deionized water (DI) water by 40–75% for various doses of ozone, presumably due to the presence of organic matter remaining in treated wastewater. Optimal UV intensities for UVA and UVC were obtained as 0.62 and 0.82 mW/cm² for all doses of ozone in synthetic spiked water samples and UV intensities beyond this resulted in lower rates of degradation of CBZ. For photo-assisted ozonation with ozone doses of 9.6 and 14.4 mg/L, rate constants were two times higher for UVA irradiations as compared to UVC irradiation. Contrary to observations in DI water, experiments in wastewater showed increase in rate of degradation with higher UV intensities. Overall, photo-assisted ozonation was found to be appropriate for both water and wastewater treatment by exploiting the benefit of direct attack of ozone and of produced ^?OH radicals to yield a greater extent of mineralization of CBZ.     

Ozonated Mineral Oil: Preparation,Characterization and Evaluation of the Microbicidal Activity

The ozonation of vegetable oils has been studied, since the produced ointments have antibacterial and fungicidal activities. However, the ozonation of mineral oils has not been reported in the literature yet, opening an interesting field for examination. In this work, we have shown the ozonation of a commercial mineral oil (Nujol). The main goal was to produce oils containing free ozone, so that this gas could act as antimicrobial agent. It was found that in Nujol, ozone remains for at least 40 days and in the sample ozonized for 15 h its concentration was 7.5 mg mL^?1. Neat Nujol showed no antimicrobial activity against the tested microorganisms, however, when ozonated it showed antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus and Escherichia coli.     

Investigation of gaseous ozone as an anti‐fungal fumigant for stored wheat

In this study, gaseous ozone was used as a fungicide to preserve stored wheat. The following operating parameters were investigated for their effects on the fungicidal efficacy of ozone: (1) the applied ozone dose; (2) ozonation time; (3) water activity of the wheat; and (4) temperature of the wheat. The effect of ozonation on germination of the wheat was also studied. Experimental results revealed that gaseous ozone was very effective in the inactivation of fungi associated with the wheat. Within 5 min of ozonation, 96.9% of the fungal spores were inactivated by applying 0.33 mg of ozone (g wheat)^?1 min^?1. It was also found that increases in both water activity and temperature of the wheat enhanced the fungicidal efficacy of ozone. In addition, results of this study indicated that the inactivation processes could be controlled by simply monitoring the ozone exiting from the reactor and, consequently, the time‐consuming microbial examination processes could be avoided. This finding would make the application of ozone in the preservation of cereal grains easier, simpler, and more cost‐effective. It was also found that although the applied ozone doses above certain thresholds may reduce the germination of wheat, the inactivation of fungi could be achieved using applied ozone doses far below those thresholds. Copyright © 2006 Society of Chemical Industry     

Physicochemical and Bioactive Compounds of ‘Cantaloupe’ Melon: Effect of Ozone Processing on Pulp and Seeds

Melon seeds are an important source of bioactive compounds, which are considered to be health beneficial. Therefore, the objective of this work was to assess the impact of gaseous ozone treatments (30 and 60 min) on melon seeds paste (nonedible part) and compare with the effect on pulp (edible part). Ozone treatments were evaluated in terms of physicochemical (color, pH, and soluble solids content) and nutritional profiles (total phenolics, total carotenoids, and total antioxidant capacity) of processed material. Results indicate that ozone has a different impact on the two fruit matrices, being seeds less affected by this preservation treatment.     

Distinct synergetic effects in the ozone enhanced photocatalytic degradation of phenol and oxalic acid with Fe3+/TiO2 catalyst

In this work, phenol and oxalic acid(OA) degradation in an ozone and photocatalysis integrated process was intensively conducted with Fe~(3+)/TiO_2 catalyst. The ferrioxalate complex formed between Fe~(3+) and oxalate accelerated the removal of OA in the ozonation, photolysis and photocatalytic ozonation process, for its high reactivity with ozone and UV. Phenol was degraded in ozonation and photolysis with limited TOC removal rates, but much higher TOC removal was achieved in photocatalytic ozonation due to the generation of ·OH. The sequence of UV light and ozone in the sequential process also influences the TOC removal, and ozone is very powerful to oxidize intermediates catechol and hydroquinone to maleic acid. Fenton or photo-Fenton reactions only played a small part in Fe~(3+)/TiO_2catalyzed processes, because Fe~(3+) was greatly reduced but not regenerated in many cases.The synergetic effect was found to be highly related with the property of the target pollutants. Fe~(3+)/TiO_2 catalyzed system showed the highest ability to destroy organics, but the TiO_2 catalyzed system showed little higher synergy.     

Activated sludge process coupled with intermittent ozonation for sludge yield reduction and effluent water quality control

BACKGROUND: Ozone is applied in wastewater treatment for effluent water quality improvement (post‐ozonation) as well as for excess sludge reduction (in the recirculation line). There is some evidence that ozone dosed directly to aerobic biooxidation (ABO) process enhances degradation of recalcitrant compounds into intermediates, following their biodegradation in the same reactor. However, no information regarding the influence of ozone on sludge yield in this system was found. Therefore, the current work aimed to evaluate the effect of ozone on the sludge yield when ozone is dosed directly to the ABO process. In addition, batch and continuous treatment schemes for phenolic wastewater treatment are compared. RESULTS: The results revealed that an optimal ozone dose of ～30 mgO₃ L^?1 day^?1 reduced the sludge yield by ～50%, while effluent water quality in terms of total chemical oxygen demand (TCOD), compared with a conventional ABO process, was improved by 35.5 ± 3.6%. Slight improvement in soluble COD removal at the same ozone dose was also detected. The toxicity of effluent water was reduced as the ozone dose was increased. CONCLUSIONS: In an integrated ozonation‐ABO process it is possible to simultaneously reduce sludge yield and to improve effluent water quality, as COD and toxicity are reduced. Copyright © 2011 Society of Chemical Industry     

Impact of ozonation on subsequent treatment of azo dye solutions

BACKGROUND: Aqueous solutions of four azo‐dyes, Acid Red 14 (AR14), Congo Red (CR), Reactive Black 5 (RB5), and Reactive Violet 5 (RV5) were treated with ozone, and the impact of ozonation on their subsequent treatability by aerobic biodegradation processes was investigated. RESULTS: In all cases, ozonation at the highest ozone doses investigated could remove more than 96% of the original dye, and the corresponding residual colour of the azo dye solutions declined to less than 20 on the Pt‐Co scale. Ozonation also resulted in reduction of chemical oxygen demand (COD), total organic carbon (TOC) the COD/TOC ratio and pH, while in all cases electrical conductivity of the dye solutions increased. Activity of the microbial colonies present in domestic wastewater was not inhibited when un‐ozonized solutions of these dyes were mixed in a 1:1 volumetric ratio with domestic wastewater, although the dyes themselves were not degraded. Also, no significant inhibition of microbial activity was observed in 1:1 mixtures of ozonized dye solutions and domestic wastewater, especially when the initial dye concentration was low and the applied ozone dose was high. In almost all cases, progressively enhanced BOD exertion was observed in mixtures containing dye solutions ozonized with progressively higher doses. This indicated that some ozonation by‐products of the above dyes could be degraded by microorganisms present in domestic wastewater. CONCLUSIONS: It was concluded that the above dye solutions, after ozonation for partial or complete colour removal, could be mixed with domestic wastewater for subsequent treatment by aerobic biological processes, with no adverse impact on the activity of the microbial colonies present in domestic wastewater. Copyright © 2007 Society of Chemical Industry     

Combination of biological and chemical processes for the treatment of textile wastewater containing reactive dyes

The treatment of a segregated textile wastewater containing reactive dyes was investigated in two continuous‐flow process trains using ozonation and biological processes. The degree of decolorization and dissolved organic carbon (DOC) removal achieved by ozonation followed by aerobic treatment (two‐stage) was compared with that found when an anaerobic and aerobic pretreatment was added (four‐stage). Although the biological pretreatment reduced color by ～70%, similar amounts of ozone were required in both trains to achieve high degrees of overall removal of color and DOC. In both trains, ozonation increased biodegradability in the following aerobic reactor, however, in order to reach ～80% overall DOC removal, a specific ozone absorption (A*) of ～6 gO₃ gDOC_o^?1 was required and >50% of the DOC was mineralized in the ozone reactor. A comparison of cost estimates based on investment and operating costs for the process alternatives showed that a four‐stage train would reduce costs only if it enabled a decrease in A* to less than 2 gO₃ gDOC_o^?1. Difficulties in comparing treatment processes for segregated vs full‐stream wastewaters are discussed. Copyright © 2003 Society of Chemical Industry     

Microbial Counts and Antibiotic Resistances during Conventional Wastewater Treatment and Wastewater Ozonation

ABSTRACT

In view of the increasing interest in the occurrence and spread of antibiotic-resistant bacteria due to wastewater treatment systems into the environment, total colony counts and antibiotic-resistant bacteria were determined in regard to a conventional wastewater treatment plant and its upgrade with a wastewater ozonation. To cope with the elimination of conventionally not sufficiently decimated micropollutants, the Eifel-Rur Waterboard built a full-scale ozonation plant at the stream Wurm, which is strongly influenced by WWTP discharge. To evaluate the effect of wastewater ozonation on the receiving water’s biocenosis, extensive monitoring of the WWTP and its receiving water is performed before and after implementation of ozonation treatment and in preliminary pilot-scale ozonation experiments. Total colony counts showed no significant difference between the stream Wurm upstream and downstream of the WWTP and were slightly below the average of comparable investigations. Antibiotic resistances showed only a little differences between WWTP and the stream samples. Furthermore, no accumulation of antibiotic resistances was found at the conventional WWTP. Pilot-scale ozonation yielded a reduction of total colony counts of fecal indicator bacteria Escherichia coli and Enterococci after ozone treatment. The pilot-scale experiments gave no indication that ozone treatment leads to a rise in antibiotic resistances against selected antibiotics of different antibiotic classes.