Ozonation System Research Articles

Pharmaceuticals removal from natural water by nanofiltration combined with advanced tertiary treatments (solar photo-Fenton, photo-Fenton-like Fe(III)–EDDS complex and ozonation)

The main purpose of the study was to compare three different advanced tertiary treatments, solar photo-Fenton, solar photo-Fenton-like Fe(III)–EDDS complex and ozonation. Five pharmaceuticals, carbamazepine, flumequine, ibuprofen, ofloxacin, and sulfamethoxazole, selected as model micropollutants for the study, were dissolved (15μgL−1) in natural water. The nanofiltration system consisted of two 5.2m2 membranes operated in parallel. The solar photo-Fenton experiments were carried out in a 3m2 compound parabolic collector pilot plant having a 35L total volume. The ozonation system was a pilot plant providing a maximum concentration of 8.82gO3h−1. Contaminants were measured by ultra-performance liquid chromatography, previously preconcentrated by solid phase extraction. Nanofiltration provided a large volume of practically clean water (permeate) and a concentrated stream requiring further treatment. General advantages of the combined process over direct treatment due to reduction in the total volume to be treated were: (i) lower AOP treatment time, (ii) more efficient reagent consumption, and (iii) lower acid consumption for carbonate removal. The photo-Fenton-like Fe(III)–EDDS complex makes it possible to work at over pH6. Ozone consumption was lowered by combining ozonation with nanofiltration instead of using direct ozonation.

Is adsorption an artifact in experimentation with Triclosan?

AbstractThis paper examines the effect of adsorption of Triclosan (TCS) onto labware on the results obtained during lab-scale experiments. Three sets of experiments were considered; two of them expose the problem in water or wastewater treatability studies and the other one in microbial susceptibility testings. In the former two sets, lab-scale systems; ozonation; and membrane filtration (NF/RO) that are commonly used in water or wastewater treatability studies were utilized and the distribution of TCS within the systems were followed. The ozonation labware tested was composed of a Pyrex reactor with plastic and glass tubings. The NF/RO system was composed of a stainless steel feed tank, a stainless steel membrane unit, stainless steel flanges, and stainless steel and plastic tubings. Ozonation system was operated without ozone gas, but air. Similarly, NF/RO system was without membrane in it. Both of the systems were rinsed with methanol before experiments to remove any possible earlier contamination. Dur...

P-Nitrophenol Enhanced Degradation in High-Voltage Pulsed Corona Discharges Combined with Ozone System

Degradation of p-nitrophenol (PNP) in aqueous solution by high-voltage pulse corona discharges (HVPD) combined with ozone was investigated in this study. Experimental results showed that 96 % of PNP (380 mg/L) can be degraded within 30 min using a combined technology. Additionally, the effects of initial concentration of PNP, synergistic effect of both techniques, and pH of the aqueous solution on PNP degradation were evaluated. This combined technology achieved better results than using two mineralization techniques in series which indicates that synergistic effect of HVPD and ozone promoted pollutant decomposition. On the other hand, weak alkalinity was favorable for PNP removal. In the end, intermediate products resulting from PNP degradation processes were analyzed by ion chromatography and high performance liquid chromatography-tandem mass spectrometry. Main intermediate products, including p-benzoquinone, nitro benzoquinone, trans-muconic acid, maleic acid, acetic acid, formic acid, NO2 − and NO3 − were identified. It was proposed a possible reaction pathway.

The CaroMont Health Ozone Laundry System: Energy Savings, Improved Laundered Product Qualities and Return on Investment at Gaston Memorial Hospital, Gastonia, NC

Ozone-generating equipment was retrofit into the laundry washroom of the Gaston Memorial Hospital in Gastonia, NC, and began operating in the early part of July, 2010. Three ozone-generating systems service six washer-extractors in the washroom. The performance of this fine-bubble ozone diffusion laundering system has been monitored since that time, with various adjustments made to ensure optimum performance and production results. Since installing this ozone system, the laundry has realized $46,000 per year savings in utility costs as well as reduction in water consumption of more than 1,000,000 gal per year, and lower wastewater discharge fees. In addition, the ozone-washed linens are cleaner and brighter than ever and the rewash rate has been reduced by 1.5–2.5%. The apparent Return on Investment (ROI) of this ozone laundering system, calculated on the basis of just these benefits cited, is 16 months.

Cork boiling wastewater treatment at pilot plant scale: Comparison of solar photo-Fenton and ozone (O3, O3/H2O2). Toxicity and biodegradability assessment

Remediation of cork boiling wastewater was studied as an example of complex industrial wastewater treatment by applying a protocol based on a combination of advanced technologies and chemical–biological assays. Solar photo-Fenton and ozone (alone or in combination with hydrogen peroxide at different pH conditions), at pilot plant scale have been used as chemical oxidation step. Additionally, the effect of a physic-chemical pre-treatment using different flocculants (FeSO4 and FeCl3) was evaluated. Although physic-chemical pre-treatment with Fe3+ provided good removals of COD, DOC and TSS, it was found that it did not enhance solar photo-Fenton post-treatment. On the contrary, ozone-based process was improved after physic-chemical pre-treatment with Fe3+, attaining higher degradation efficiencies with lower ozone consumptions for the combination with O3 at initial pH 7. Toxicity and biodegradability assays were performed to evaluate possible variations along the oxidation processes. After solar photo-Fenton treatment, toxicity and biodegradability remained constant at their initial values. Then, Zahn–Wellens test was carried out to study long term biodegradability and possible biomass adaptation to the partially photo-treated effluent. Decrease in toxicity values and short term biodegradability enhancement were observed for cork boiling wastewater treated by ozonation systems.

Energy consumption of three different advanced oxidation methods for water treatment: a cost-effectiveness study

Abstract The present work provides an economic comparative study of three TiO 2 -based advanced oxidation technologies for removing two well known contaminants from water. The relative costs and outcomes of catalytic ozonation (TiO 2 /O 3 in dark), photocatalytic oxidation (TiO 2 /UVA/O 2 ), and photocatalytic ozonation (TiO 2 /UVA/O 3 ) were compared with regard to the degradation of oxalic acid and dichloroacetic acid as model compounds. The combination of TiO 2 , UVA, and O 3 showed the highest cost-effectiveness among the assessed methods. In the case of oxalic acid decomposition, the cost-effectiveness of catalytic ozonation and photocatalytic oxidation was about two and nine times less than that of photocatalytic ozonation. For the degradation of dichloroacetic acid, catalytic ozonation and photocatalytic oxidation were two and 15 times more expensive than photocatalytic ozonation systems with regard to their output. These results were explained well by the synergistic effects on the generation of hydroxyl radicals using photocatalytic ozonation systems.

Combined catalytic ozonation and membrane system for trihalomethane control

Water containing humic acid causes membrane fouling and the formation of disinfectant by-products, such as trihalomethanes (THMs), after chlorination. In this research, heterogeneous catalytic ozonation was used with a ceramic membrane system to investigate its effect on the prevention of membrane fouling and the formation of THMs. Ozone and nitrogen gases were injected into the membrane system with or without TiO2, which was used as the catalyst. The effects of operating conditions such as gas flow rate, catalyst dosage, and ozone dosage were investigated. The results show that permeate fluxes recovered up to 78% and 93% when ozonation alone and catalytic ozonation were applied in the hybrid system, respectively. The recovery rate of permeate flux increased with increasing ozone gas flow rate. The THM concentrations in the chlorinated permeate water significantly decreased when TiO2 and ozone gas were injected into the hybrid system. An increase of TiO2 dosage in catalytic ozonation resulted in a decrease of THM formation in the chlorinated permeate water. This study shows that the proposed hybrid system can be effective for permeate flux recovery and THM formation control.

A full scale anaerobic–anoxic–aerobic process coupled with low-dose ozonation for performance improvement

The effectiveness of RAS degradation under low dose ozone and effect of ozonated sludge on a full scale anaerobic-anoxic-aerobic (A/A/O) process were examined. The ratios of chemical oxygen demand (COD) to nitrogen and COD to phosphorus of ozonated sludge were 23 and 91 respectively on average, much higher than in influent. Compared with the performance of A/A/O process alone, COD removal efficiency slightly decreased after insertion of the ozonation system. Ammonia removal became more stable, but total nitrogen and total phosphorus removal efficiency was not improved. Sludge volume index (SVI) of activated sludge reached to an optimal value of 80-120 mL/g quickly due to ozonation combined with A/A/O process which reduced the danger of sludge bulking. Overall, the combination of biological process with ozonation at a low dose rate shows promise. Compared with higher dose ozonation, low-dose ozonation can improve the performance of A/A/O effectively at a smaller cost.

The control of bromate formation in ozonation of bromide-containing water

Bromate formation under different conditions of ozone-based treatment for bromide-containing water was investigated. The paper not only presented common influencing factors such as temperature, pH, addition of ammonia or hydrogen peroxide, but also explored the effect of utilization of metallic compounds containing magnesium oxide, titanium oxide, potassium permanganate, and copper sulfate. The results showed that bromate formation could be significantly inhibited by increasing acidity, addition of ammonia or permanganate. And cooling the ozonation system is an alternative to control bromate formation.

Mechanism considerations for photocatalytic oxidation, ozonation and photocatalytic ozonation of some pharmaceutical compounds in water

Aqueous solutions of four pharmaceutical compounds, belonging to the group of emergent contaminants of water: atenolol (ATL), hydrochlorothiazide (HCT), ofloxacin (OFX) and trimethoprim (TMP), have been treated with different oxidation systems, mainly, photocatalytic oxidation, ozonation and photocatalytic ozonation. TiO2 has been used as semiconductor for photocatalytic reactions both in the presence of air, oxygen or ozone-oxygen gas mixtures. Black light lamps mainly emitting at 365 nm were the source of radiation. In all cases, the influence of some variables (concentrations of semiconductor, ozone gas and pharmaceuticals and pH) on the removal of pharmaceuticals, total polyphenol content (TPC) and total organic carbon (TOC) was investigated. A discussion on the possible routes of pharmaceutical and intermediates (as TPC and TOC) elimination has been developed. Thus, OFX TiO2/UVA degradation mechanism seems to develop through the participation of non-hydroxyl free radical species. Furthermore, the presence of OFX inhibits the formation of hydroxyl radicals in the photocatalytic process. The most effective processes were those involving ozone that lead to complete disappearance of parent compounds in less than 30 min for initial pharmaceutical concentrations lower than 2.5 mg L−1. In the ozonation systems, regardless of the pH and the presence of TiO2, pharmaceuticals are degraded through their direct reaction with ozone. Photocatalytic ozonation was the most efficient process for TPC and TOC removals (≥ 80% and ≥60% elimination after 2 h of treatment, respectively) as well as in terms of the ozone consumption efficiency (1, 5.5 and 4 mol of ozone consumed per mol of TOC mineralized, at pH 4, 7 and 9, respectively). Weakly acid conditions (pH 4) resulted to be the most convenient ones for TPC and TOC removal by photocatalytic ozonation. This was likely due to formation of hydroxyl radicals through the ozonide generated at these conditions.

Effect of inlet ozone concentration on the performance of a micro-bubble ozonation system for inactivation of Bacillus subtilis spores

A novel ozonation system based on micro-bubble technique was applied as a disinfection process in this study. The effect of inlet ozone concentration on the disinfection performance was comprehensively investigated. Bacillus subtilis spore was used as a model microorganism to evaluate the disinfection performance. In the micro-bubble ozonation system is operated at the same ozone dosage, the log reduction under high inlet ozone concentration was extremely higher than that under low inlet ozone concentration within 3min of contact time. When the contact time was 3min, the log reduction at the inlet ozone concentration of 140mg/L was 5.2, which was nearly ten times of that at the inlet ozone concentration of 40mg/L (0.5-log reduction). In addition, the ozone utilization efficiency was also enhanced by increasing the inlet ozone concentration. A decrease in bubble diameter was found under higher inlet ozone concentration and the interfacial area per unit volume of the micro-bubble was significantly higher due to the reduction in bubble diameters. This observation can well explain the increase in mass-transfer coefficient (KLa) and the enhancement in the ozone utilization efficiency. The result of this study showed that raising inlet ozone concentration is a promising method which could enhance the disinfection performance in a micro-bubble ozonation system.

Inhibition mechanism of [formula omitted] formation over MnOx/Al2O3 during the catalytic ozonation of 2,4-dichlorophenoxyacetic acid in water

BrO3- formation from Br− containing drinking water ozonation treatment remains an important challenge. The inhibition mechanism of BrO3- formation was investigated during the catalytic ozonation of 2,4-dichlorophenoxyacetic acid (2,4-D) in mesoporous alumina supported MnOx (MnOx/Al2O3) suspension. The catalyst exhibited both significant inhibition of BrO3- formation and highly efficient catalytic ozonation of 2,4-D. Based on the characterization of UV–Vis spectrum, H2O2 determination and CV analysis, a redox process of bromine species occurred during the oxidation of 2,4-D in catalytic ozonation system. BrO3- reduction to Br− and the reduction of HBrO were responsible for the inhibition of BrO3- formation over MnOx/Al2O3 with ozone. An inhibition mechanism of BrO3- formation was proposed for catalytic ozonation in MnOx/Al2O3 suspension based on all experimental results. These observations will facilitate the development of catalytic ozonation for drinking-water treatment, especially for purification of Br− containing water.

Application of catalytic ozonation in treatment of dye from aquatic solutions

Decomposition of Basic Blue 9 (BB-9) in aqueous solution using ozonation and catalytic ozonation system (O3/granular activated carbon [GAC]) in the bench-scale experiment was investigated. The effect of ozone dose, pH, and GAC contents in removal of BB-9 and biodegradability of effluent such as Biochemical Oxygen Demand (BOD5); Chemical Oxygen Demand (COD), and BOD5/COD were studied. Results show that pH of solution and ozone concentration are significant factors on removal of BB-9; COD and BOD5. Kinetic studies of reactions indicated that reactions followed the first-order kinetics model. The application of GAC as catalyst, in mass concentration of 2 g/l, caused 48% increase in the degradation rate of BB-9. Ozonation process caused an increase in biodegradability of BB-9. However, catalytic ozonation did not have an effect on the biodegradability of the effluent. Acute toxicity tests with Daphnia magna show that this applied treatment method can significantly decrease toxicity of dye in aquatic solutions.

Mineralization of bisphenol A by catalytic ozonation over alumina

Total mineralization of bisphenol A (BPA) has been investigated through non-catalytic and catalytic ozonation treatments in a semi-batch reactor. Non-catalytic ozonation led to complete degradation of BPA in less than 4min, but did not convert the by-products of BPA ozonation completely. In sole ozonation systems only 35% conversion of the total organic carbon (TOC) was achieved in 60min. Using 1g/L alumina catalyst increased the TOC removal to 90%. Study of the effect of catalyst particles showed that by reducing the particle size from pellets to powder, TOC removal increased significantly from 44% to 90% under particular reaction conditions. However, increasing the amount of alumina catalyst from 0.5g/L to 4g/L did not show a strong effect on the TOC removal. Catalyst reusability and deactivation studies indicated that catalyst showed stable activity after three consecutive cycles of catalytic ozonation. A two-stage kinetic regime was used to express rate of TOC removal for both non-catalytic and catalytic ozonation of BPA.

Hierarchical porous ceramic membrane with energetic ozonation capability for enhancing water treatment

In this work, we proposed a facile method for preparation of hierarchical porous ceramic membrane with energetic catalytic ozonation capability aiming at enhancing the performance of water treatment by using the combined ozone-membrane system. The strategy involved preparation of TiO2 macroporous membrane as a backbone and subsequently coating it with mesoporous Ti–Mn catalyst layer. Scanning electron microscope, transmission electron microscope and nitrogen sorption isotherms characterization demonstrated that the TiO2 membrane was composed of TiO2 nanorods with 200–400nm diameter, 5μm length, and mesoporous Ti–Mn layer was coated on the membrane surface uniformly with the thickness of about 100nm and pore size of 10nm. Energy dispersive X-ray spectroscopy, X-rays photoelectron spectroscopy and X-ray diffractometer showed that Ti–Mn mixed oxide was spread into the inner voids of the membrane to form a hierarchical porous structure. Treating simulated wastewater (aqueous solution of dye Red-3BS and Aniline) it was found that hierarchical porous catalytic membrane exhibited high catalytic ozonation capability which resulted in an enhancement of membrane antifouling, separation and degradation of organic pollutants when the membrane was used as a key device in the combined membrane and ozone system.

Degradation of 17β-estradiol in aqueous solution by ozonation in the presence of manganese(II) and oxalic acid

Natural estrogens, such as 17β-estradiol (E2), are the main substances responsible for estrogenic activity found in domestic sewage. In the work described herein, the degradation of E2 has been investigated by single ozonation and catalytic ozonation in the presence of manganese ion (Mn2+) and oxalic acid. The presence of Mn2+ and oxalic acid in the ozonation processes significantly improved the E2 degradation and, hence, the reduction of estrogenic activity in aqueous solution. The addition of Mn2+ and oxalic acid produced many more hydroxyl radicals in the catalytic ozonation system than in the single ozonation system. Oxidation products formed during ozonation of E2 have been identified by means of gas chromatography–mass spectrometry (GC-MS), on the basis of which a possible reaction pathway for E2 degradation by ozonation is proposed. E2 was first oxidized to hydroxyl-semiquinone isomers, and these were subsequently degraded to low molecular weight compounds such as oxalic acid and malonic acid. The latter were easily oxidized by ozone to form carbon dioxide (CO2). The results demonstrate that the ozonation–Mn2+–oxalic acid system may serve as a powerful tool for removing E2, and the addition of Mn2+ and oxalic acid is favourable for the complete removal of estrogenic activity induced by steroid estrogens in aqueous solution.

Purification of water containing mycoestrogens using ozonation and nanofiltration

Abstract This study investigated the efficiency of mycoestrogens removal from water using the sequential combinations of two processes: ozonation and nanofiltration. The results were compared with ones obtained for water treatment via ozonation and nanofiltration performed as single-stage operations. The removal of mycoestrogens was improved using the combination of ozonation–nanofiltration processes in comparison to single-stage ozonation system, while a negligible difference was observed with nanofiltration. However, the analyzed system improved the nanofiltration membrane capacity. Ozonation before membrane filtration limited the intensity of the membrane blocking, which adjusted the use of the complex systems in water treatment.

Bromate Formation in Ozone and Advanced Oxidation Processes

Both the direct ozone reaction and the indirect hydroxyl radical reaction are important in ozonation of drinking water. This article investigates the effectiveness of ozone versus the advanced oxidation process of ozone coupled with hydrogen peroxide in the formation of bromate. The investigation was conducted on a pilot scale at various H2O2:O3 dose ratios of 0.1, 0.2, and 0.35 at different times of the year. The results of this study show a reduction in bromate with the addition of hydrogen peroxide to an ozone system versus ozone alone. It was also observed that bromate increased with increased H2O2:O3 ratios; however, concentrations were still lower than those in the ozone only system.

Methylene blue removal from contaminated waters using heterogeneous catalytic ozonation promoted by natural zeolite: mechanism and kinetic approach

This paper presents experimental results of a methylene blue removal system based on heterogeneous catalytic ozonation in the presence of natural zeolite. The effect of pH (2–10) and the presence of radical scavengers (acetate ions) on homogeneous and heterogeneous ozonation systems are assessed at laboratory scale. Results show that heterogeneous catalytic ozonation using natural zeolite increases methylene blue removal rate with respect to the single ozonation process at all pH values. The inhibitory effect of free-radical scavengers is impaired by zeolite, suggesting that methylene blue oxidation reactions take place mainly on the zeolite surface. The increase in methylene blue removal rate could be related to ozone interaction with hydroxyl groups present on the zeolite surface (, S‒OH, S‒O−), which plays a key role in the reaction mechanism.

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.