Ozonation System Research Articles

A Review of Ozone Systems Costs for Municipal Applications. Report by the Municipal Committee – IOA Pan American Group

ABSTRACTOzone has proven effective in improving water treatment plant performance, increasing customer satisfaction, and meeting increasingly stringent regulatory requirements. The benefits include disinfection; reducing chlorine disinfection by-products; micro-coagulation; enhanced filter performance; biological filtration; oxidation of iron, manganese, sulfide, taste- and odor-causing compounds, pharmaceuticals and personal care products (PPCPs), and endocrine disrupting compounds (EDCs). Despite the effectiveness of ozone in water treatment, a perception remains that ozone may be too expensive for consideration at many water treatment facilities. This paper presents an evaluation by the Municipal Committee of the International Ozone Association (IOA-MC) that aims to provide a realistic assessment of the current capital and operating costs of ozone in the North American water treatment practice. A general strategy is proposed for developing preliminary estimates of ozone capital and operating costs that could be used by engineers and/or owners for planning purposes. The information presented may benefit utilities, managers, and engineers engaged in the evaluation of treatment options.

Biological stability in the ozone and peroxone pretreatment systems in river water

Biological stability in the ozone and peroxone pretreatment systems in river water

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

ABSTRACTThe 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.

Optimization of UV/H2O2 and ozone wastewater treatment by the experimental design methodology

ABSTRACTThe objective of this study was to optimize UV/H2O2 and ozonation systems by means of an experimental design using as a response the efficiency of the operational conditions to remove the methylene blue (MB) dye. Two classes of experimental planning were used: the Doehlert matrix (DM) and the central composite design (CCD). The most important variables for each process were hydrogen peroxide concentration, the ratio of illuminated volume/total volume of the reactor and recirculation flow rate for UV/H2O2, and ozone flow rate, consumed ozone and MB concentration for the ozonation. The DM was more efficient in optimizing the systems, since it used a smaller number of experiments and achieved similar results when compared to the CCD. After optimization, the disinfection efficiency of the systems was tested with secondary effluent evaluating the inactivation of microbiological indicators, Escherichia coli and total coliforms, using the optimized and the worst condition previously obtained with MB removal as response. The inactivation efficiencies in the optimum conditions were about 99%, allowing an efficient disinfection as well as the production of an effluent with quality to be reused according to specific legislations, while at the worse conditions, the inactivation did not reach standards for reuse.

Ozone Content over the Russian Federation in 2017

The review is based on the operation results of the system for total ozone (TO) monitoring in the CIS and Baltic countries functioning in the operational regime at the Central Aerological Observatory (CAO). The monitoring system uses data from the national network equipped with M-124 filter ozonometers being under the methodological supervision of the Main Geophysical Observatory. The quality of the entire system functioning is operationally controlled in CAO through the comparison with the observations obtained from the OMI satellite equipment (NASA, USA). Basic TO observation data are generalized for each month of the fourth quarter of 2017, for the whole fourth quarter, and for the whole year. The data of routine observations of surface ozone values in the Moscow region and Crimea are also considered.

Free Radical and Direct Ozone Reaction Competition to Remove Priority and Pharmaceutical Water Contaminants with Single and Hydrogen Peroxide Ozonation Systems

ABSTRACTFrom the application of concepts derived from the gas-liquid absorption film model, the competition between ozone reactions with 72 water emerging or priority contaminants (pharmaceuticals, pesticides, polynuclear aromatic hydrocarbons, etc.) and the initiation steps of the hydroxyl radical decomposition of ozone in ozone alone and combined with hydrogen peroxide oxidation systems has been studied. With this information, the ozone preferential reaction, that is, the ozone direct reaction or the formation of free radicals and the kinetic absorption regime are known. In a second step, the ratio of removal rates of the contaminants studied by reacting with hydroxyl radical and ozone has also been estimated. With this, the way contaminants are preferentially removed (from their reaction with ozone or from the reaction with free radicals) can also be known and, hence, whether or not an ozone advanced oxidation system is convenient to be applied. For instance, most of the contaminants studied in this work at concentrations lower than 50 μgL−1 and hydrogen peroxide at concentrations lower than 50 mgL−1 react with ozone under chemical control regime so that both direct and free radical reactions theoretically compete. However, under chemical control, typical concentration of scavengers present in wastewater or surface water would inhibit the free radical reactions and, at least theoretically, for many contaminants studied here, the direct ozone reaction is the principal removal way. When mass transfer controls the process rate only contaminants with a hydroxyl and ozone rate constant ratio ≥ 1.6x106 M-1s-1 would be preferentially removed through free radical way.

Iron doped fibrous-structured silica nanospheres as efficient catalyst for catalytic ozonation of sulfamethazine.

Sulfonamide antibiotics are ubiquitous pollutants in aquatic environments due to their large production and extensive application. In this paper, the iron doped fibrous-structured silica (KCC-1) nanospheres (Fe-KCC-1) was prepared, characterized, and applied as a catalyst for catalytic ozonation of sulfamethazine (SMT). The effects of ozone dosage, catalyst dosage, and initial concentration of SMT were examined. The experimental results showed that Fe-KCC-1 had large surface area (464.56m2g-1) and iron particles were well dispersed on the catalyst. The catalyst had high catalytic performance especially for the mineralization of SMT, with mineralization ratio of about 40% in a wide pH range. With addition of Fe-KCC-1, the ozone utilization increased nearly two times than single ozonation. The enhancement of SMT degradation was mainly due to the surface reaction, and the increased mineralization of SMT was due to radical mechanism. Fe-KCC-1 was an efficient catalyst for SMT degradation in catalytic ozonation system.

Ozonation control and effects of ozone on water quality in recirculating aquaculture systems

To address the undesired effect of chemotherapeutants in aquaculture, ozone has been suggested as an alternative to improve water quality. To ensure safe and robust treatment, it is vital to define the ozone demand and ozone kinetics of the specific water matrix to avoid ozone overdose. Different ozone dosages were applied to water in freshwater recirculating aquaculture systems (RAS). Experiments were performed to investigate ozone kinetics and demand, and to evaluate the effects on the water quality, particularly in relation to fluorescent organic matter. This study aimed at predicting a suitable ozone dosage for water treatment based on daily ozone demand via laboratory studies. These ozone dosages will be eventually applied and maintained at these levels in pilot-scale RAS to verify predictions. Selected water quality parameters were measured, including natural fluorescence and organic compound concentration changes during ozonation. Ozone reactions were described by first order kinetics. Organic matter, assessed as chemical oxygen demand and fluorescence, decreased by 25% (low O3), 30% (middle O3) and 53% (high O3), while water transmittance improved by 15% over an 8-day period. No fish mortality was observed. Overall, this study confirms that ozone can improve RAS water quality, provides a better understanding of the ozone decay mechanisms that can be used to define further safe ozone treatment margins, and that fluorescence could be used as a monitoring tool to control ozone. This study might be used as a tool to design ozone systems for full-scale RAS by analysing water sample from the specific RAS in the laboratory.

Design Considerations for Cost-Effective Ozone Mass Transfer in Sidestream Systems

ABSTRACTOzone dissolution system design is important for meeting transfer efficiency (TE) goals. Large sidestream pump flow (L) and high venturi inlet pressure improves TE but increases operating cost. Ozone TE was examined at a 25 gpm (97-Lpm) pilot-scale sidestream system with (SSw-dg) and without (SSwo-dg) degas separation. Under constant ozone dose conditions, process operating parameters were varied including sidestream gas/liquid (G/L) ratio, venturi-inlet water pressure, venturi-outlet water pressure, feed gas pressure, and ozone gas concentration. Performance results included determination of TE, ozone exposure (CTHDT), and hydraulic detention time (THDT). Several design aspects of sidestream ozone systems were examined to improve mass transfer by using remixing devices, protecting ozone gas piping from corrosion, calculating sidestream ozone residual, and driving force for mass transfer. Moisture contamination of ozone supply lines may cause corrosion and/or decomposition of ozone gas that releases heat and destroys ozone. Ozone gas piping design is critical to prevent trapping water that might enter gas pipe during power outage or when units are offline. During plant operation below design flow, multiple constant speed pumps or variable speed pumps were evaluated to reduce overall operating costs.

Synchronously degradation benzotriazole and elimination bromate by perovskite oxides catalytic ozonation: Performance and reaction mechanism

Abstract Ozonation showed a good capacity on micro-emerging pollutants degradation from water or wastewater treatment, but its leading to the formation of toxic bromate. Bromate inhibition in catalytic ozonation treatment remained an important challenge. In this study, a novel catalytic ozonation was promoted using perovskite oxide as catalyst, showing good performance on synchronously degradation benzotriazole (BZA) and elimination bromate. LaCoO3 exhibited significant catalytic activity for BZA degradation, with complete degradation achieved at 15 min, and about 71% BrO3− inhibition, compared with single ozonation. LaFeO3 showed no catalytic activity for BZA degradation but inhibited the generation of BrO3− by 73%. Further investigation involving reactive oxygen species, important intermediates, the structure and surface chemical properties of the catalysts showed that H2O2 act an important effect but various in different ozonation systems. The combination of the surface hydroxyl groups on LaFeO3 with H2O2 to form [Fe-H2O2]s was found to occur in LaFeO3 catalytic ozonation, resulting the reduction of BrO3−. The production of ROS in LaCoO3 catalytic system and the cyclic of Co3+/Co2+ accelerated the BZA degradation efficiency and inhibition of BrO3−. A novel BrO3− elimination pathway was proposed, as an important contribution for the application of catalytic ozonation.

Ozonation of return activated sludge for disintegration and solubilisation with synthesized titanium oxide as catalyst

Ozonation of activated sludge in the present of titanium dioxide (TiO2) as catalyst to enhance the production of hydroxyl radical was evaluated in comparison to the sole ozonation process. In this process, the catalytic ozontion showed improvement in increasing ozone consumption and improving activated sludge disintegration and solubilisation. The reduction of total suspended solid (TSS), volatile suspended solid (VSS) and soluble chemical oxygen demand (SCOD) solubilisation was better in the catalytic ozonation system. Initial pH 7 of activated sludge was found best to disintegrate and solubilise the sludge flocs. However upon additional of sodium hydroxide (NaOH) in pH adjustment enhanced the solubilisation of organic matter from the flocs and cells, making the initial pH 9 is the best condition for activated sludge solubilisation. Yet the initial pH 7 of activated sludge supernatant was the best condition to achieve SCOD solubilisation due to sludge floc disintegration, when it had stronger correlation between TSS reduction and SCOD solubilisation (R2=0.961). Lower amount of catalyst of 100 mgTiO2/gTSS was found to disintegrate and solubilise the activated sludge better with 30.4% TSS reduction and 25.2% SCOD solubilisation efficiency, compared to 200 mgTiO2/gTSS with 21.9% and 17.1% TSS reduction and SCOD solubilisation, respectively.

State Estimation of Catalytic Ozonation by Differential Neural Networks with Discontinuous Learning Law

The aim of this study was to develop an adaptive state estimator armed with discontinuous learning laws for the catalytic ozonation system. A class of differential neural network served to estimate the uncertain section of the uncertain catalytic process. The learning laws used for adjusting the weights included in the neural network based estimator. A set of numerical simulations demonstrated the application of the DNN based state observer and showed the estimation of the non-measurable information in the catalytic ozonation system. The adaptive state estimator with discontinuous learning laws was also evaluated with experimental information. The comparison of suggested and asymptotically convergent DNN based observer demonstrated the superior estimation performance offered by the estimator introduced in this study.

Catalytic ozonation by palladium–manganese for the decomposition of natural organic matter

Abstract In this study, magnetic nanoparticles of Fe3O4/SiO2/Pd-Mn were synthesized by wet deposition method for heterogeneous catalytic ozonation to remove the organic compounds in water. The as-synthesized Fe3O4/SiO2/Pd-Mn was characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) to clarify its chemical and physical properties. SEM images indicated that the particle size of Fe3O4/SiO2/Pd-Mn was about 50–100 nm. EDS results confirmed with the XRD findings, illustrating that Pd and Mn were successfully coated on the catalyst with the at% of 1.66 and 2.40%, respectively. The degradation efficiency of organics in water was examined by A254 and dissolved organic compounds (DOC). Under heterogeneous catalytic ozonation treatment, the decomposition efficiency of A254 and DOC of raw water, from Te-Chi reservoir, achieved 70 and 60%, respectively. The decomposition efficiency of A254 and DOC increased to 80 and 90% when the pH was adjusted to 11. The calculated DOC degradation rate constant (kd) for was 6.5 × 10−2 min−1 at pH 11 via heterogeneous catalytic ozonation method. Hydroxyl radicals were dominated for the removal of organic compounds in our heterogeneous catalytic ozonation system as an evidence of 7-hydroxycoumarin generation in radical scavenger experiments. In addition, the removal efficiency of THMFPs (Trihalomethane Formation Potentials) was 74 and 38% for Fe3O4/SiO2/Pd-Mn heterogeneous ozonation and sole ozonation, repectively, illustrating the enhanced oxidation ability. The endpoint of ozonation process can be controlled by the modeling results of Nernst simulating as ORPA254 = 27240 − 14755.3 ln[A254] − 2486.91 pH + 2.64 ln[THMFPs].

Investigation of full-scale ozonation at a municipal wastewater treatment plant using a toxicity-based evaluation concept

ABSTRACT Effluents from municipal wastewater treatment plants (WWTPs) are known to be point sources of micropollutants for surface waters. The aim of this study was to examine a reconstructed full-scale ozonation equipped with a pump-injector system for ozone (O3) dosage and a fluidized moving-bed reactor as biological posttreatment at a municipal WWTP utilizing an effect-directed approach. This approach consists of chemical analysis in combination with toxicological tests for the assessment of treatment efficiency of the plant. Chemical analysis showed elimination rates > 80% for pharmaceuticals and industrial chemicals. Analysis of endocrine disruptors was limited due to substance concentrations below the limit of detection (LOD). Estrogenic activity was detected by the Arxula Adeninivorans yeast estrogen screen (A-YES) at low concentrations (pg to ng EEQ/l range). Estrogenic activity was reduced by more than 90% after ozonation. In contrast, androgenic activity (measured in the Adeninivorans yeast androgen screen, A-YAS) was still found after O3 treatment and after biological posttreatment, which is consistent with the data obtained by chemical analysis. Furthermore, no marked genotoxic or cytotoxic effects were observed after ozonation using the alkaline comet and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid (MTT) assays, respectively. Results suggest that the applied specific O3 dose of 0.4 mgO3/mgDOC is a safe operation setup in terms of toxicologically relevant transformation products. In addition, no adverse effects on primary producers, as evidenced by algae growth inhibition tests, were detected. The monitored biofilm growth in the biological posttreatment exhibited a steady state after one month. Based on computational fluid dynamics (CFD) simulations and biomass, one might conclude that O3 did not apparently enter biological posttreatment to a great extent and that hydraulic retention time in the O3 reactor was sufficient. Our data demonstrate the effectiveness of a full-scale O3 treatment in combination with a fluidized moving-bed reactor as biological posttreatment for the reduction of a majority of micropollutants without the release of relevant toxic transformation products as assessed by a chemical and toxicity-based approach.

Modular and efficient ozone systems based on massively parallel chemical processing in microchannel plasma arrays: performance and commercialization

Plasmachemical systems based on the production of a specific molecule (O3) in literally thousands of microchannel plasmas simultaneously have been demonstrated, developed and engineered over the past seven years, and commercialized. At the heart of this new plasma technology is the plasma chip, a flat aluminum strip fabricated by photolithographic and wet chemical processes and comprising 24–48 channels, micromachined into nanoporous aluminum oxide, with embedded electrodes. By integrating 4–6 chips into a module, the mass output of an ozone microplasma system is scaled linearly with the number of modules operating in parallel. A 115 g/hr (2.7 kg/day) ozone system, for example, is realized by the combined output of 18 modules comprising 72 chips and 1,800 microchannels. The implications of this plasma processing architecture for scaling ozone production capability, and reducing capital and service costs when introducing redundancy into the system, are profound. In contrast to conventional ozone generator technology, microplasma systems operate reliably (albeit with reduced output) in ambient air and humidity levels up to 90%, a characteristic attributable to the water adsorption/desorption properties and electrical breakdown strength of nanoporous alumina. Extensive testing has documented chip and system lifetimes (MTBF) beyond 5,000 hours, and efficiencies >130 g/kWh when oxygen is the feedstock gas. Furthermore, the weight and volume of microplasma systems are a factor of 3-10 lower than those for conventional ozone systems of comparable output. Massively-parallel plasmachemical processing offers functionality, performance, and commercial value beyond that afforded by conventional technology, and is currently in operation in more than 30 countries worldwide.

Solar or UVA-Visible Photocatalytic Ozonation of Water Contaminants.

An incipient advanced oxidation process, solar photocatalytic ozonation (SPO), is reviewed in this paper with the aim of clarifying the importance of this process as a more sustainable water technology to remove priority or emerging contaminants from water. The synergism between ozonation and photocatalytic oxidation is well known to increase the oxidation rate of water contaminants, but this has mainly been studied in photocatalytic ozonation systems with lamps of different radiation wavelength, especially of ultraviolet nature (UVC, UVB, UVA). Nowadays, process sustainability is critical in environmental technologies including water treatment and reuse; the application of SPO systems falls into this category, and contributes to saving energy and water. In this review, we summarized works published on photocatalytic ozonation where the radiation source is the Sun or simulated solar light, specifically, lamps emitting radiation to cover the UVA and visible light spectra. The main aspects of the review include photoreactors used and radiation sources applied, synthesis and characterization of catalysts applied, influence of main process variables (ozone, catalyst, and pollutant concentrations, light intensity), type of water, biodegradability and ecotoxicity, mechanism and kinetics, and finally catalyst activity and stability.

Mn-Fe-Mg-Ce loaded Al 2 O 3 catalyzed ozonation for mineralization of refractory organic chemicals in petroleum refinery wastewater

Abstract There is great interest in designing a cost-efficient catalytic ozonation system for refractory wastewater treatment. A novel Mn-Fe-Mg-Ce loaded Al 2 O 3 (Mn-Fe-Mg-Ce/Al 2 O 3 ) was developed to catalytically ozonate real petroleum refinery wastewater (PRW). The loadings, calcination temperature and impregnation sequence of metals significantly influenced the catalytic performance. An optimized catalyst was consisted of 2.2% MnO, 2.2% Fe 2 O 3 , 0.9% MgO and 0.9% CeO 2 . Mg and Ce were co-impregnated and then calcinated at 550 °C, followed by Mn and Fe co-impregnation and calcination at 550 °C. Mg and Ce oxides pre-loaded on the catalyst promoted an even surface distribution of multivalent Mn (Mn 4+ , Mn 3+ and Mn 2+ ) and Fe oxides (Fe 3+ and Fe 2+ ). Such evenly distributed Mn, Fe, Mg and Ce oxides greatly facilitated the hydroxyl radical generation, thus promoted mineralization of refractory organic chemicals in PRW. The Mn-Fe-Mg-Ce/Al 2 O 3 catalyzed ozonation doubled removal of total organic carbon in PRW relative to single ozonation. About 54% polar chemicals were removed, and 60% naphthenic acids and naphthenic acid esters were eliminated, indicating a high degree of mineralization. This study illustrates a potential of Mn-Fe-Mg-Ce/Al 2 O 3 catalyzed ozonation for advanced treatment of refractory wastewaters.

Degradation of mixture of three pharmaceuticals by photocatalytic ozonation in the presence of TiO2/montmorillonite nanocomposite: Simultaneous determination and intermediates identification

This study addressed the simultaneous degradation of mixture of three pharmaceuticals including metronidazole (MET), ciprofloxacin (CIP) and acetaminophen (APAP) through the photocatalytic ozonation system. TiO2 nanoparticles were immobilized onto montmorillonite (MMT) support irradiated by UVA light in the presence of ozone. The samples were characterized by XRF, SEM, TEM, PL and N2 adsorption–desorption analysis. A rapid and sensitive chemometrics technique was then developed for the simultaneous determination of the three pharmaceuticals in their mixtures during the photocatalytic ozonation process. A UV–vis spectrophotometer was used for recording the absorption of the pharmaceuticals. The concentration of these pharmaceuticals was successfully determined using a PLS method, despite the severe overlap of their spectra. A central composite design (CCD) was utilized to analyze, model and optimize the effect of each operational parameter on multiple responses including MET degradation (Y1), CIP degradation (Y2) and APAP degradation (Y3). A multi response optimization approach based on a global desirability function (DF) of the factors was employed to simultaneously maximize the response factors. 25mgL−1 MET, 5mgL−1 CIP, 5mgL−1 APAP, 10Lh−1 ozone flow rate and a 15min of reaction time were found to be the ideal conditions at which the degradation of these pharmaceuticals could be simultaneously maximized (Y1=64.60%, Y2=80.58% and Y3=50.12%). Finally, the intermediate by–products of the drugs formed in the degradation process were identified using the GC–MS technique.

Optimization of ultraviolet ozone treatment process for improvement of polycaprolactone (PCL) microcarrier performance.

Growing cells on microcarriers may have overcome the limitation of conventional cell culture system. However, the surface functionality of certain polymeric microcarriers for effective cell attachment and growth remains a challenge. Polycaprolactone (PCL), a biodegradable polymer has received considerable attention due to its good mechanical properties and degradation rate. The drawback is the non-polar hydrocarbon moiety which makes it not readily suitable for cell attachment. This report concerns the modification of PCL microcarrier surface (introduction of functional oxygen groups) using ultraviolet irradiation and ozone (UV/O3) system and investigation of the effects of ozone concentration, the amount of PCL and exposure time; where the optimum conditions were found to be at 60,110.52ppm, 5.5g PCL and 60min, respectively. The optimum concentration of carboxyl group (COOH) absorbed on the surface was 1495.92nmol/g and the amount of gelatin immobilized was 320±0.9µg/g on UV/O3 treated microcarriers as compared to the untreated (26.83±3µg/g) microcarriers. The absorption of functional oxygen groups on the surface and the immobilized gelatin was confirmed with the attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) and the enhancement of hydrophilicity of the surface was confirmed using water contact angle measurement which decreased (86.93°-49.34°) after UV/O3 treatment and subsequently after immobilization of gelatin. The attachment and growth kinetics for HaCaT skin keratinocyte cells showed that adhesion occurred much more rapidly for oxidized surfaces and gelatin immobilized surface as compared to untreated PCL.

Ozone Plant Operations Under Drought Conditions

ABSTRACTThe Metropolitan Water District of Southern California (Metropolitan) owns and operates five potable water treatment plants. Currently four of the treatment plants utilize ozone as the primary disinfectant. The Metropolitan ozone contactors are over-under baffled and include 10 chambers, an afterbay, and an effluent channel. Ozone is generally added in either the first countercurrent gas/liquid flow chamber (Chamber 1) or the first and second (co-current gas/liquid flow) chambers. Disinfection credit is received from ozone residuals in Chambers 2 through 6. An ozone destruct system collects and destroys ozone off-gases from Chambers 1 through 9 and an ozone quenching system is used to minimize dissolved ozone from leaving the contactors. Severe drought in California, and resulting water supply limitations, have created significant operational issues ranging from reduced plant flows to source water changes and water quality challenges. The combination of reduced flow and different source water conditions resulted in the ozone systems being operated occasionally under unfamiliar conditions. This article discusses some of the challenges faced in operating the ozone plants at low flows and low ozone production rates. Further, water quality issues required prudent management of operations to meet regulatory requirements. From the lessons learned, several recommendations are offered in preparation for similar conditions in the future.