Simultaneous Ozonation Research Articles

Continuous Ozonation Coupled with UV-C Irradiation for a Sustainable Post-Harvest Processing of Vaccinium macrocarpon Ait. Fruits to Reduce Storage Losses

Ozonation and UV irradiation are promising sustainable methods for extending the shelf life of stored fruits. The aim of this research was to evaluate the effectiveness of the constructed system, enabling simultaneous ozonation and UV-C irradiation of cranberry fruits in extending their shelf life. The effectiveness of this solution was determined by analyzing the properties of fruits subjected to the processes. The impact of these processes on the shelf life of fruits was assessed during 42 days of storage at a temperature of 8 °C and 80% humidity. It was demonstrated that applying the ozonation process to fruits, as facilitated by the developed solution’s throughput, led to a reduction in microbiological load (fermentation bacteria count reduction by 3.4 log cfu−1), resulting in an extension of their shelf life and a reduction in storage losses (8.98% by mass). The implementation of the developed solution, by reducing water loss and limiting fruit losses (approximately 5% less compared to the control group) during storage, contributes to tangible benefits for the producers and distributors of these fruits. The proposed modification has a positive environmental effect by reducing waste and makes the cultivation of cranberries more sustainable and environmentally friendly.

Simultaneous ozonation of ethylbenzene and fluorene in water, soil, and air

Most of the studies regarding aromatic hydrocarbon degradation by ozone focus on individual treatment. Hence, two aromatic hydrocarbons, ethylbenzene (ETB) presented in water and fluorene (FL) distributed in soil, were selected to be eliminated simultaneously in water, soil, and air using ozone. In this study, the effect of the physicochemical properties of ETB and FL, the distribution of FL on sandy and agricultural soils, and the influence of the presence of moisture in both soils were analyzed. The chemical composition of the agricultural soil (mainly metal oxides) enhanced the FL degradation by the possible catalytic ozone decomposition into reactive species, such as •OH, O2•−, H2O2, O3•−, and O•, which reduced its treatment time 4.5-fold in this solid matrix compared to the sandy soil. Moreover, the moisture liberated from water by the gas flow and adsorbed on the soil bed (up to 0.33% at 180 min) reduced the ozonation time 2-fold in the agricultural and sandy soils, due to the •OH formation. Contrary to FL, the rapid elimination of ETB (< 20 min) in both soils did not allow to observe the possible effect of reactive species generation on ETB decomposition due to the low amount of moisture accumulated during this time (<0.06%). The proposed simultaneous ozonation scheme permitted to achieve up to 96% and 100% of the ETB and FL decomposition. Some identified by-products, such as maleic, malonic, oxalic, and formic acids, suggest that ozone and possible reactive species formed on the soil surfaces reacted with both compounds, leading to non-toxic simple by-products with their partial mineralization (≈80%), which was proven by a toxicity evaluation (phytotoxicity and eco-toxicity). The rapid and efficient simultaneous ozonation of aromatic hydrocarbons in water, soil, and air (only ETB) proves the feasibility of ozone to treat different organic pollutants in more than one phase.

G-C3N4 for Photocatalytic Degradation of Parabens: Precursors Influence, the Radiation Source and Simultaneous Ozonation Evaluation

Graphitic carbon nitride (g-C3N4) is a promising catalyst for contaminants of emerging concern removal applications, especially as a visible-light-driven material. In this study, g-C3N4 catalysts were effectively synthesized through a simple thermal polymerization method, using melamine, urea, and thiourea as precursors to elucidate the influence of these compounds on the final product’s photocatalytic performance. The degradation of a mixture of three parabens was investigated under different types of radiation: two artificial, ultraviolet-A (UVA) and visible LED, and natural sunlight. The urea-based catalyst (UCN) presented better results under all radiation sources, followed by thiourea, and finally, melamine. Among the artificial light sources, the degradation of parabens under UVA was considerably higher than visible—up to 51% and 21%, respectively—using UCN; however, the broader spectrum of natural sunlight was able to achieve the highest removals, up to 92%, using UCN. Comparing artificial radiation sources, UVA lamps presented 45% lower energy consumption and associated costs. Photocatalytic ozonation was tested using UCN and MCN, with UCN once more possessing superior performance and a synergetic effect between photocatalysis and ozonation, with complete removal under 12 min. The use of g-C3N4 was then successfully tested in initial screening and found to be an efficient alternative in more low-cost and feasible solar photocatalysis water treatment.

Simultaneous Ozonation of Ethylbenzene and Fluorene in Water and Soil. Effect of Physicochemical Properties of Soil

Simultaneous Ozonation of Ethylbenzene and Fluorene in Water and Soil. Effect of Physicochemical Properties of Soil

Behaviour of ozone in the hybrid ozonation-coagulation (HOC) process for ibuprofen removal: Reaction selectivity and effects on coagulant hydrolysis

Simultaneous ozonation and coagulation can be realized in one unit in the developed hybrid ozonation-coagulation (HOC) process. To reveal the reaction sequence within the HOC process, the ibuprofen (IBP) removal efficiency of the ozonation only, HOC and HOC-PO43− (inhibition of the reactions between ozone and metal coagulant) processes at pH 5 and different ozone dosages were investigated. The removal efficiency is almost the same for the three processes at a low ozone dosage (4.8 mg/L), and higher removal performance can be achieved by the HOC process with increasing ozone dosage. It can be implied that ozone preferentially reacts with OH− to generate OH which react with IBP in the HOC process, and subsequently reacts with the surface hydroxyl groups of hydrolysed Al species to enhance OH generation. Moreover, based on the kinetics, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) analyses, the synergistic reactions between ozone and the metal coagulants (SOC) started to take effect from ozone dosage of 9.6 mg/L, which further verified that ozone will be involved in the IBP ozonation prior to the SOC reactions. The subsequent SOC reactions also resulted in the increased generation of polymeric Al species and more abundant intermediates in the HOC process.

Impact of Ozone Used-Alone and Coagulation Aid Treatment on The Reduction of Trihalomethanes Components

The whole research paper examines the impact of ozone as either a just use-alone and coagulation benefit, mainly upon the reduction of dissolved organic carbon from the water with a moderate rate of DOC 10.75 mg/land CaCO3 calcium hardness 300 mg/l. A raw water sample has been taken from the Tigris River (Baghdad, Iraq) was being adopted in research work. The performance of ozone therapy has been assessed by calculations of DOC, DOC quantities, UV254, as well as total trihalomethane (TTHM). Research findings have shown that with 0.9 mg O3/mg DOC ozone use-alone, approximately 60% UV254 reduction and approximately 28% DOC reduction will occur.DOC fractionation analysis indicates that within the water samples, ozone could alter the composition of DOC, transform the hydrophobic fractions toward hydrophilic fractions and reduce TTHM. Ozone was also responsible for a significant reduction in particle stability as well as the dissolved calcium content. Improved water flocculation and improved DOC removal were triggered by these simultaneous ozonation effects. This resulted in a decrease in the coagulant dosage while the dosage of ozone is considerably higher over 0.3 mg O3/mg DOC has added before ferric sulfate coagulation. The pre-ozonation coagulation method also accomplished favorable removal of TTHM with all tested ozone doses (0 to 0.9 mg O3/mg DOC), resulting in lower TTHM during pre-ozonated coagulated waters unlike those through related ozonated waters.

Mechanisms for simultaneous ozonation of sulfamethoxazole and natural organic matters in secondary effluent from sewage treatment plant

Mechanisms for simultaneous ozonation of sulfamethoxazole and natural organic matters in secondary effluent from sewage treatment plant

Improvement of Co-Composting by a combined pretreatment Ozonation/Ultrasonic process in stabilization of raw activated sludge

The enhancement of composting technology to stabilize sludge pretreated by ozonation and ultrasonic was tested for 35 days. Secondary sludge produced by biological process are characterized with endogenous residue and inert solid matter which inhibit fully degrade bacterial cell walls. The composting process was performed with sludge pretreated with ozonatian and ultrasonics and green waste in a ratio of 2:1. The composting characteristics was evaluated for different physico-chemical and microbiological parameters in five different reactors. A high degree of composting quality was achieved with respect to significant reduction in volatile solids (VS) (32%), total organic carbon (TOC) (35.0%), C/N ratio (23.74), total coliform (TC) (168) along with the substantial increase in availability of nutrients like N (1.2%) and P (8.77%). High removal efficiency of TC and Fecal Coliform (FC) were observed in composting results, where simultaneous ultrasonic and ozonation were considered as primary-stabilization process. Therefore, applying integrated ultrasonic/ozonation with composting system for sludge stabilization is potentially useful technology in sustainable land restoration practices to meet standards and produce soil conditioner.

Simultaneous ozonation of 90 organic micropollutants including illicit drugs and their metabolites in different water matrices

The ozonation of 90 chemically diverse organic micropollutants (OMPs) including four classes of illicit drugs and their metabolites was studied in pure buffered water, tap water and wastewater effluent at three specific ozone doses and three pH levels.

Effects of ozone as a stand-alone and coagulation-aid treatment on the reduction of trihalomethanes precursors from high DOC and hardness water

This study investigates the effect of ozone as a stand-alone and coagulation aid on the removal of dissolved organic carbon (DOC) from the water with a high level of DOC (13.8 mgL−1) and calcium hardness (270 mgL−1) CaCO3.Natural water collected from the Assiniboine River (Manitoba, Canada) was used in this study.Effectiveness of ozone treatment was evaluated by measurement of DOC, DOC fractions, UV254, and trihalomethane formation potential (THMFP). Additionally, zeta potential and dissolved calcium concentration were measured to discern the mechanism of ozone reactions.Results indicated that 0.8 mg O3/mg DOC ozone stand-alone can cause up to 86% UV254 reduction and up to 27% DOC reduction.DOC fractionation results showed that ozone can change the composition of DOC in the water samples, converting the hydrophobic fractions into hydrophilic ones and resulting in the reduction of THMFP. Also, ozone caused a decrease in particle stability and dissolved calcium concentration. These simultaneous ozonation effects caused improved water flocculation and enhanced removal of DOC. This resulted in reduction of the coagulant dosage when ozone doses higher than 0.2 mg O3/mg DOC were applied prior to coagulation with ferric sulfate. Also, pre-ozonation-coagulation process achieved preferential THMFP removal for all of the ozone doses tested (0–0.8 mg O3/mg DOC), leading to a lower specific THMFP in pre-ozonated-coagulated waters than in the corresponding ozonated waters.

Removal of arsenic, phosphates and ammonia from well water using electrochemical/chemical methods and advanced oxidation: A pilot plant approach

The purpose of this work was to develop a pilot plant purification system and apply it to groundwater used for human consumption, containing high concentrations of arsenic and increased levels of phosphates, ammonia, mercury and color. The groundwater used was obtained from the production well in the Vinkovci County (Eastern Croatia). Due to a complex composition of the treated water, the purification system involved a combined electrochemical treatment, using iron and aluminum electrode plates with simultaneous ozonation, followed by a post-treatment with UV, ozone and hydrogen peroxide. The removal of the contaminant with the waste sludge collected during the electrochemical treatment was also tested. The combined electrochemical and advanced oxidation treatment resulted in the complete removal of arsenic, phosphates, color, turbidity, suspended solids and ammonia, while the removal of other contaminants of interest was up to 96.7%. Comparable removal efficiencies were obtained by using waste sludge as a coagulant.

THE ELECTROCOAGULATION/ADVANCED OXIDATION TREATMENT OF THE WELL WATER FROM ŽUPANJA

The work was development and application of the purification system suitable for the treatment of groundwater used for human consumption as well as watering of the plants in the system for the hydroponic cultivation of tomatoes. For that purpose the well water from the 60 m deep water layer situated near the city of Županja (Eastern Croatia) was processed. Most of the measured parameters exceeded upper permissible limit (UPL) for drinking water. The concentrations of the parameters color, turbidity, iron, manganese, arsenic, phosphates, chemical oxygen demand and ammonia were as follows 292±20 mg/PtCo, 21±5 NTU, 1.72±0.34 mg/L, 0.075±0.014 mg/L, 0.074±0.011 mg/L, 10.4±1.7 mg/L, 37±1 mg/L and 1.2±0.1 mg/L, respectively. Due to the complex composition of the treated water, the purification system required the combination of electrochemical treatment, using iron and aluminum electrode plates with simultaneous ozonation followed by post treatment with hydrogen peroxide and ozone. The electrocoagulation/ozonation approach was used for the removal of heavy metals, color, turbidity, phosphates and partially organic matter while the rest of the organic contaminants and ammonia were removed by the treatment with hydrogen peroxide and ozone. Following the combined electrochemical treatment and post treatment with hydrogen peroxide and ozone all measured parameters in the treated water were in agreement with regulated values. The combined treatment resulted in total removal of arsenic, color, turbidity, ammonia and organic contaminants while the removal of other parameters of interest was up to 97.98%.

Preparation of drinking water used in water supply systems of the towns Zrenjanin and Temerin by electrochemical methods

The aim of this work was the development and application of the pilot plant with the capacity of 1000 L/day for the purification of groundwater used for human consumption characterized with high concentration of arsenic and increased values of organic pollutants, ammonia, nitrites, color and turbidity. For that purpose, groundwater from the production wells supplying the towns Zrenjanin and Temerin (Vojvodina, Serbia) was used. Due to its complex composition, the purification system required the combination of the electroreduction/electrocoagulation, using iron and aluminum electrode plates with/without ozonation, followed by the electromagnetic treatment and the finally by the simultaneous ozonation/UV treatment. The electroreduction was used for the removal of nitrates, nitrites, and Cr(VI), while the removal of arsenic, heavy metals, suspended solids, color and turbidity required the application of the electrocoagulation with simultaneous ozonation. Organic contaminants and ammonia were removed completely in the last treatment step by applying the simultaneous ozonation/UV treatment. All measured parameters in the purified water were significantly lower compared to the regulated values. Under the optimum treatment conditions, the removal efficiencies for color, turbidity, suspended solids, total arsenic, total chromium, Ni(II), total copper, sulfates, fluorides, chemical oxygen demand, ammonia, nitrates, and nitrites were 100%. The removal efficiencies of the total manganese and iron were 85.19% and 97.44%, respectively, whilst the final concentrations were 4 and 7 μg/L, respectively.

Application of Individual and Simultaneous Ozonation and Adsorption Processes in Batch and Fixed-Bed Reactors for Phenol Removal

Ozonation, adsorption onto activated carbon and catalytic ozonation in batch and in a fixed-bed reactor for the removal/degradation of phenol and COD were investigated. In the case of batch ozonation the oxidation capacity was greater than 6.9 g of phenol/g O3, while the continuous ozonation system degraded 40% of the phenol and reduced the COD by 27.9%. The adsorption process provided over 99% removal for phenol and COD; however, it treated only 5 L compared with 17 L for the combined process, which also increased the total area and pore volume of the activated carbon, due to the formation of pores and a widening of micropores.

Characterization and electrochemical treatment of landfill leachate

A combined treatment approach using advanced oxidation, electrochemical methods and microwaves was developed and applied for the treatment of landfill leachate taken from Piskornica (Koprivnica, Croatia) sanitary landfill. Due to the complex nature of the effluent and extremely low bio-degradability (BOD5/COD ratio = 0.01) the purification of the leachate started with pre-treatment with ozone followed by simultaneous ozonation and electrocoagulation/electrooxidation using the set of iron and aluminum electrodes, and finally, the degradation of organic residue and ammonia with microwaves. Applied treatment approach resulted in clear, colorless and odorless effluent with the values of all measured parameters significantly lower compared to the upper permissible limit for discharge into the environment. The removal percentages of the parameters: color, turbidity, suspended solids, ammonia, COD and iron following the combined treatment were 98.43%, 99.48%, 98.96%, 98.80%, 94.17% and 98.56%, respectively.

A comparison between catalytic ozonation and activated carbon adsorption/ozone-regeneration processes for wastewater treatment

Two methods based on the use of granular activated carbon (GAC) and ozone to remove organic compounds from water have been investigated. Both methods have been applied to degrade an aqueous solution of gallic acid and a secondary effluent from a wastewater treatment plant (WWTP). One of the methods, namely catalytic ozonation, implies simultaneous ozonation and adsorption onto GAC. This process takes advantage of the oxidizing power of ozone and the adsorption capacity of GAC but also of the catalytic transformation of ozone into secondary oxidants on the GAC surface. The efficiency of catalytic ozonation was compared to those of single adsorption and single ozonation. It was found that the catalytic process highly improves the conversion of total organic carbon (TOC) and makes a more efficient use of ozone than the single ozonation process. To illustrate the reusability of the catalyst, the GAC was reused four times through a series of consecutive experiments. No loss of catalytic activity was observed when treating the WWTP effluent but some deactivation could be appreciated when treating the aqueous solution of gallic acid. This deactivation could be attributed to some porosity destruction and surface oxidation produced as a result of reactions of aqueous ozone on the GAC surface. The other method investigated is an adsorption-regeneration process (namely GAC/O3-regeneration) that comprises two steps: dynamic adsorption onto GAC and further regeneration of the spent GAC with gaseous ozone. The adsorption stage of the GAC/O3-regeneration experiments was carried out in a continuous flow adsorption column and breakthrough curves were obtained. It was observed that the GAC used in this work adsorbed gallic acid very efficiently but exhibited limited capacity to remove chemical oxygen demand (COD) from the WWTP effluent. The optimum ozone dose to regenerate the spent GAC after gallic acid adsorption was found to be about 0.4gO3/gGAC, with results showing around 90% regeneration efficiency. As a result of incomplete regeneration, the GAC adsorption capacity progressively decreased with the number of adsorption–regeneration cycles. The GAC/O3-regeneration method was not successful at treating the WWTP effluent as low adsorption uptake was observed. Moreover, the GAC became damaged after regeneration because of excessive oxidation of its surface.

Ozonation of pharmaceutical compounds: Rate constants and elimination in various water matrices

The ozonation of four pharmaceuticals (metoprolol, naproxen, amoxicillin, and phenacetin) in ultra-pure (UP) water was studied in the pH range between 2.5 and 9. The experiments allowed the determination of the apparent rate constants for the reactions between ozone and the selected compounds. The values obtained varied depending on the pH, and ranged between 239 and 1.27 × 10 4 M −1 s −1 for metoprolol; 2.62 × 10 4 and 2.97 × 10 5 M −1 s −1 for naproxen; 2.31 × 10 3 and 1.21 × 10 7 M −1 s −1 for amoxicillin; and 215 and 1.57 × 10 3 M −1 s −1 for phenacetin. Due to the acidic nature of these substances, the degree of dissociation of each pharmaceutical was determined at every pH of work, and the specific rate constants of the neutral and ionic species formed were evaluated. Additionally, the simultaneous ozonation of the pharmaceuticals in different water matrices was carried out by considering a groundwater, a surface water from a public reservoir, and three secondary effluents from municipal wastewater treatment plants. The influence of the operating conditions (initial ozone dose, nature of pharmaceuticals and type of water) on the pharmaceuticals elimination efficiency was established, and a kinetic model was proposed for the evaluation of the partial contribution to the global oxidation of both, the direct ozonation reaction and the radical pathway.

Treatment of trace organics in membrane concentrates I: pesticide elimination

The objective of this study was to eliminate organic micropollutants in the membrane system concentrates, which is produced by drinking water production plants, in order to protect existing water resources. This work is divided into two parts, pesticide elimination (I) and natural organic matter removal (II) in membrane system concentrates. Seven commonly detected pesticides in French surface waters, i.e. atrazine, sulcotrione, bentazone, isoproturon, diuron, glyphosate and acetochlore, were selected as the model micropollutants. Removal/degradation of these pesticides was studied by testing conventional processes employed for potable water production, i.e. adsorption, oxidation by ozone and clarification. Only partial removal of these pesticides was achieved with conventional processes. Removal of nonpolar pesticides was obtained by adsorption and rapid degradation of most of the pesticides was observed with low ozone dosages, except for atrazine and its metabolites. On the other hand, only the phosphonate-based pesticides were removed by clarification. By combining these processes, however, almost complete removal of the selected pesticides was achieved. Simultaneous ozonation and adsorption in the same reactor seems to be the most promising option for this study.

Kinetics of the transformation of phenyl-urea herbicides during ozonation of natural waters: Rate constants and model predictions

Oxidation of four phenyl-urea herbicides (isoproturon, chlortoluron, diuron, and linuron) was studied by ozone at pH=2, and by a combination of O 3/H 2O 2 at pH=9. These experiments allowed the determination of the rate constants for their reactions with ozone and OH radicals. For reactions with ozone, the following rate constants were obtained: 1.9±0.2, 16.5±0.6, 393.5±8.4, and 2191±259 M −1 s −1 for linuron, diuron, chlortoluron, and isoproturon, respectively. The rate constants for the reaction with OH radicals were (7.9±0.1)×10 9 M −1 s −1 for isoproturon, (6.9±0.2)×10 9 M −1 s −1 for chlortoluron, (6.6±0.1)×10 5 M −1 s −1 for diuron, and (5.9±0.1)×10 9 M −1 s −1 for linuron. Furthermore, the simultaneous ozonation of these selected herbicides in some natural water systems (a commercial mineral water, a groundwater, and surface water from a reservoir) was studied. The influence of operating conditions (initial ozone dose, nature of herbicides, and type of water systems) on herbicide removal efficiency was established, and the parameter R ct (proposed by Elovitz, M.S., von Gunten, U., 1999. Hydroxyl radical/ozone ratios during ozonation processes. I. The R ct concept. Ozone Sci. Eng. 21, 239–260) was evaluated from simultaneous measurement of ozone and OH radicals. A kinetic model was proposed for the prediction of the elimination rate of herbicides in these natural waters, and application of this model revealed that experimental results and predicted values agreed fairly well. Finally, the partial contributions of direct ozone and radical pathways were evaluated, and the results showed that reaction with OH radicals was the major pathway for the oxidative transformation of diuron and linuron, even when conventional ozonation was applied, while for chlortoluron and isoproturon, direct ozonation was the major pathway.

Removal of Pyrene and Benzo(a)Pyrene from Contaminated Water by Sequential and Simultaneous Ozonation and Biotreatment

The removal of pyrene and benzo(a)pyrene from contaminated water by sequential and simultaneous ozonation-bioremediation techniques was investigated. During the sequential treatment, ozonation using 0.5 or 2.5 mg/L ozone was used as a pretreatment process, whereas, during the simultaneous treatment process, ozonation of hydrocarbon-contaminated water at a predetermined duration using 0.5 mg/L ozone was made in the presence of microbial biomass. Ozonation was not beneficial for the removal of pyrene. However, despite a decreased specific biodegradation rate, ozonation improved the overall elimination of benzo(a)pyrene during both treatment processes. The overall removal of benzo(a)pyrene increased from 23 to 91% after exposure of the water to 0.5 mg/L ozone for 30 minutes during the simultaneous treatment process and further to 100% following exposure to 2.5 mg/L ozone for 60 minutes during the sequential treatment mode, demonstrating the benefits of combined ozonation-biological treatment for the removal of polycyclic aromatic hydrocarbons.