Ozone Oxidation Process Research Articles

Use of Ozone, UV, and Advanced Oxidation Processes For Reclaimed Water Treatment, Disinfection, and Microcontaminant Destruction

Use of Ozone, UV, and Advanced Oxidation Processes For Reclaimed Water Treatment, Disinfection, and Microcontaminant DestructionMany regions of the United States, experiencing rapid population growth and faced with the challenge of meeting increased water demands, are turning to reclaimed water as an alternative water supply source. Concurrent with the rising need for reclaimed water is the rising public concern over emerging pathogens and micropollutants. As part of the WateReuse Foundation's (WRF) project on "Innovative...Author(s)Shubhra JainJess C. BrownAndrew T. SalvesonKaumudi P. AtapattuTavy WadeMarsha A. PryorKarl G. LindenJeanette Thurston-EnriquezSourceProceedings of the Water Environment FederationSubjectSession 1: Advanced Treatment Technologies for Compounds of Emerging ConcernDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jul, 2007ISSN1938-6478SICI1938-6478(20070729)2007:6L.66;1-DOI10.2175/193864707786542698Volume / Issue2007 / 6Content sourceMicroconstituents ConferenceFirst / last page(s)66 - 85Copyright2007Word count113Subject keywordsInnovative TreatmentAdvanced OxidationReclaimed WaterOzoneUltraviolet LightPeroxideDisinfectionMicrocontaminants

Degradation of Endocrine Disrupting Chemicals by Ozone/AOPs

The presence of endocrine-disrupting compounds (EDCs) in the aqueous environment is of increasing concern due to their adverse impact on aquatic life, and potential risk to human health. Among the EDCs of concern are steroidal estrogenic hormones such as estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2), which have a high environmental prevalence and strong estrogenic activity. In addition, the extensive use of alkylphenol ethoxylates (APnEOs), bisphenol A (BPA) and phthalate compounds have resulted in an environmental presence at significant concentrations, although they appear to have a lower estrogenic activity than the steroidal hormones. As water and wastewaters are some of the primary routes of exposure to EDCs, it is important to determine at what levels EDCs are found in these media and how these levels may be reduced. Hence, it is necessary to understand the fate of EDCs in conventional water and wastewater treatment plants, as well as the efficacy of more specialized treatment methods, such as adsorption and oxidation. This paper is a summary of the latest information on the degradation of prominent EDCs by ozone and ozone-based advanced oxidation processes (AOPs). From this review, it is clear that ozone and AOPs are effective in degrading these EDCs, with the possible exception of phthalates, which are relatively stable to ozone oxidation. Knowledge of the formation of reaction products from the treatment by ozone and AOPs is relatively poor at present, and particularly for the non-steroid compounds.

Decomposition of gas-phase toluene by the combination of ozone and photocatalytic oxidation process (TiO2/UV, TiO2/UV/O3, and UV/O3)

The gas-phase toluene removal efficiencies by photocatalytic oxidation (TiO2/UV), the combination of ozone and photocatalytic oxidation (TiO2/UV/O3), and the UV/O3 reaction were tested using a quartz tube photoreactor. The experiments were conducted under various ozone concentrations (3.3–15ppm), toluene concentrations (1–9ppm), relative humidity (5–80%), and gas flow rates (200–1200mL/min). The toluene oxidation rates (TORs) of TiO2/UV/O3, and UV/O3 reactions were proportional to the ozone concentrations. The TORs of TiO2/UV, TiO2/UV/O3, and UV/O3 reactions increased with toluene concentration. However, there were negative correlations between the toluene removal efficiencies of these three kinds of reactions and the toluene concentrations. The order of the TORs and the CO2 yield rates of these three reactions were TiO2/UV/O3>TiO2/UV>UV/O3. The kinetics of TiO2/UV, and TiO2/UV/O3 reactions fit the Langmuir–Hinshelwood rate form. The rate constants (k) and Langmuir adsorption constants (K) are as follows: TiO2/UV: k=0.0102ppmm/s, K=0.146ppm−1; TiO2/UV/O3: k=0.0268ppmm/s, K=0.0796ppm−1. The reciprocal of UV/O3 reaction rate showed a positive linear relationship with the reciprocals of humidity and of toluene concentration. Ozone, also an air pollutant, was removed in the TiO2/UV/O3, and UV/O3 reactions. The ozone removal efficiency of TiO2/UV/O3 reaction in the presence and absence of toluene ranged from 61.1 to 99.5% and 38.1 to 95.1%, respectively.

Oxidative decomposition of Acid Brown 159 dye in aqueous solution by H 2O 2/Fe 2+ and ozone with GC/MS analysis

The oxidative degradation of metal-complex Co(II) Acid Brown 159 in aqueous solution by H 2O 2/Fe 2+ and ozone was investigated. Optimal conditions for decolorization and total decomposition processes were found for dye oxidation during H 2O 2/Fe 2+ and ozone treatments. The full 100% decolorization is attained during first minutes of H 2O 2/Fe 2+ and ozone oxidation processes. The complete mineralization of aqueous solutions of Acid Brown 159 dye cannot be achieved even under the optimal reaction conditions. Fenton's process appeared to be more effective in comparison with ozonation. A tentative mechanistic pathway for the oxidative degradation of Acid Brown 159 dye in aqueous solution was postulated.

Elimination of resin acids by advanced oxidation processes and their impact on subsequent biodegradation

Wood pulping and paper production generate a considerable amount of wastewater, containing many pollutants among them resin and fatty acids. Resin acids contribute substantially to effluent toxicity and were identified to be detrimental to microorganisms of activated sludge and in particular to bacteria in anaerobic wastewater treatment system and other forms of aquatic life. The objective of the present study was to check the applicability of the ozone and advanced oxidation processes (AOPs) to eliminate resin acids from aqueous solutions and to determine the ozone dose required. Furthermore, an investigation of the influence of the oxidation methods on subsequent biological destruction of the byproducts was performed. Aqueous solution of the resin acids: abietic, dehydroabietic and isopimaric acids with different initial composition were subjected to ozonation or AOP processes at different ozone doses. After ozonation or advanced oxidation pretreatment the model solutions were biodegraded in aerated vessels containing activated sludge. During ozonation of the resin acids aqueous solutions the resin acids were almost eliminated, however the reduction of chemical oxygen demand (COD) was rather low. The ozone dose required to obtain reduction of resin acids >90% was in the range of 0.1–0.7 mgO 3/mgCOD, depending on the composition and concentration of model solutions. The toxicity of ozonated resin acids solutions decreased with increasing applied ozone dose up to about 0.3–0.5 mgO 3/mgCOD, thereafter increased. Ozonation and other AOP processes did not increase the rate of biodegradation of resin acids model solutions in aerated activated sludge systems compared to not pretreated solutions.

The Effect of Salts on Ozone Oxidation Processes

Much research on ozone oxidation is performed using model wastewaters, containing a number of organic compounds to be degraded. In some cases they contain low concentrations of inorganic buffers to stabilize the pH during the experiments. In practical applications, however, salts and detergents may be present as well. The effect of such compounds on the process has to be investigated to prevent unexpected results in pilot- or full-scale applications. To quantify these effects, experiments have been performed on model waste waters in the absence and the presence of high concentrations of several inorganic salts. The oxidation selectivity in these experiments was interpreted using Hammett free-energy relationships. The effect of the different salt concentrations on the oxidation selectivity when considering reactions in the bulk of the liquid was seen to be small. This implicates the design of an ozone-based oxidation system can often be based on literature or calculated data regarding reaction rates. However, the effect of increased salt concentrations on ozone solubility and bubble size distribution may have implications for the reactor design, as these factors affect the mass transfer efficiency.

The important role of the hydroxy ion in phenol removal using pulsed corona discharge

The characteristics of phenol removal by pulsed corona discharge using multi-point-disk electrodes reactor have been investigated to identify the important role of OH − in phenol removal and the degradation mechanism. The removal efficiency of phenol was highest at about 150 rpm of the disk electrode. Decreasing the gap of electrodes or increasing the repetition rate of pulse could benefit to the phenol removal. Reactive species could be produced not only from dissociation of water vapor and O 2 but also from N 2. The formation of HNO 3 mainly resulted in the decrease in pH, and the decrease in pH in return resulted in the decrease of phenol removal rate. The ozone was formed from radical reactions, then diffused into solution and oxidized the phenols. The radicals very near the solution surface could also have the possibility to diffuse into solution and oxidize the phenols in the liquid–gas interface. The basic media could improve the ozone oxidation processes, but the acidic media could worsen them.

高濃度オゾン酸化法による金属Ａｌ膜の酸化過程とそれを用いて作製した強磁性トンネル接合膜の磁気抵抗効果

高濃度オゾン酸化法による金属Ａｌ膜の酸化過程とそれを用いて作製した強磁性トンネル接合膜の磁気抵抗効果

Ozone kinetics and diesel decomposition by ozonation in groundwater

The ozone kinetics (ozone auto-decomposition; effects of pH and solubility) and diesel/TCE/PCE decomposition (effects of hydroxyl radical scavenger, pH, and ozone/H2O2) by ozonation process were investigated in aqueous phase using deionized water, simulated groundwater, and actual groundwater. Reactions with deionized water and groundwater both showed the second-order reaction rates: the reaction rate was much higher in groundwater (half-life of 14.7 min) than in deionized water (half-life of 37.5 min). It was accelerated at high pH condition in both waters. The use of ozone showed high oxidation rates of TCE, PCE, and diesel. Hydroxyl radical scavengers acted as inhibitors for diesel decomposition, and high pH condition and addition of hydrogen peroxide could promote to degrade diesel in groundwater indicating ozone oxidation process could be effectively applied to treating diesel contaminated-groundwater.

Ozone oxidation in a rotating packed bed

AbstractThe feasibility of applying a novel rotating packed bed to the ozone oxidation process is investigated. Ozone oxidation experiments were conducted to examine how various operating variables affect the decolorization of dyes in aqueous solutions system. Rotor speeds ranged from 380 to 1748 rpm, providing 10∼202 equivalent gravitational force. Experimental results indicate that the centrifugal force positively affects the decolorization efficiency. Furthermore, it is shown that owing to its low ozone mass transfer resistance, a rotating packed bed can be used to increase the efficiency of the ozone oxidation process. Our results further demonstrate that the decolorization efficiency increases with either an decreasing initial dye concentration or liquid flow rate.© 2003 Society of Chemical Industry

Application of Ozone and Advanced Oxidation Processes to the Treatment of Lye-Wastewaters from the Table Olives Industry

An important fraction of wastewaters generated in the black table olives industry results from the treatment of the olives with sodium hydroxide for debittering and darkening of the fruit. These lye-wastewaters are characterized by a high presence of organic compounds, mainly phenols and polyphenols. The decomposition of that organic content was studied by means of several chemical treatments: ozonation alone and combined with hydrogen peroxide or UV radiation, as well as UV radiation alone and combined with hydrogen peroxide. The degradation levels and the effect of the additional presence of H2O2 and UV radiation on the organic matter removal were established for these processes. An approximate kinetic study was conducted, which led to the evaluation of the rate constants for the organic matter reduction. In a second phase, non-pretreated lye-wastewaters and preozonated wastewaters were degraded biologically by means of aerobic microorganisms. The evolution of the organic matter and the biomass were followed. It was demonstrated that the pretreatment with ozone significantly enhances the efficiency of the aerobic process, increasing both the substrate removal level and the degradation rate. This enhancement is probably due to the elimination of most of the toxic phenolic compounds and the increase of the biodegradability in the ozonation pretreatment.

Degradation of carbofuran by using ozone, UV radiation and advanced oxidation processes

The degradation of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate), a frequently used carbamate derivative pesticide that is considered a priority pollutant, is carried out in batch reactors by means of single oxidants: ozone, UV radiation and Fenton’s reagent; and by the advanced oxidation processes (AOPs) constituted by combinations of ozone plus UV radiation, UV radiation plus H2O2, and UV radiation plus Fenton’s reagent (photo-Fenton system). For all these reactions, the apparent pseudo-first-order rate constants are evaluated in order to compare the efficiency of each process. In addition and by means of a competition kinetic model, the rate constants for the reaction of carbofuran with ozone and with hydroxyl radicals are also determined. The improvement in the decomposition levels of carbofuran reached by the combined processes in relation to the single oxidants, due to the generation of the very reactive hydroxyl radicals, is also established in every process. For the oxidant concentrations applied, the most effective process in removing carbofuran was the photo-Fenton system.

Initial oxidation process by ozone on Si(1 0 0) investigated by scanning tunneling microscopy

Ozone is a strong oxidant due to its release of atomic oxygen. The initial ozone oxidation process at room temperature and the roughness of the interface were investigated using scanning tunneling microscopy (STM). The most favorable adsorption site was the bridge site on the Si dimer at initial oxidation using ozone gas. Less than 10% of the oxygen atoms on the surface were located at the bridge site between the Si dimers. The rest of the oxygen atoms were inserted into the backbond below the Si dimer atom near the defects. This indicates that the oxygen atom is inserted into the backbond of the Si dimer through original and etched defects. The interface of SiO2/Si was characterized after the oxide film was removed by hydrofluoric acid. STM images were obtained from the etched surface. The roughness of the STM image was below 0.2 nmrms. This result indicates that the interface between the silicon and ozone oxides limits the roughness to two to three SiO2 layers at most after oxidation by ozone.

Influence of Ozone and Advanced Oxidation Processes on Biological Treatment of Textile Wastewater

Ozonation and advanced oxidation processes (AOPs) were applied to biological aerobic treatment of industrial wastewater. Textile wastewater consisted of: an anthraquinone dyestuff, an anionic detergent, a softening agent and NaCl. Biodegradation was carried out either in a 2 dm3 aerated reactor with activated sludge or in a trickled bed reactor with biofilm. The ozonation process was carried out in a 1.5 dm3 stirred cell reactor equipped additionally with UV lamp. A test of inhibition of microbial growth of activated sludge in the textile wastewater under the influence of various oxidants applied in the AOPs has been carried out. The inhibitory effect of the AOPs on microbial growth accounts for only 10 %, while untreated wastewater exhibits 47 % of inhibition. Kinetics of microbiological destruction of the pollutants was described by the Monod equation. The kinetic parameters were identified based on the data of experiments. The influence of various AOPs on the kinetics of biodegradation was analyzed.

Removal of Humic Substances by Oxidation/Biofiltration Processes - a Review

The paper is concerned principally with summarising the experience to-date of treating low alkalinity, low turbidity, humic-rich surface waters by the combination of ozone oxidation and biological filtration processes. In the UK, USA and other countries, upland coloured waters have often been treated by slow sand filtration in which only moderate removals of DOC have been achieved (< 20%). The presence of significant levels of humic matter in filtrate waters has led to difficulties in achieving compliance with the standards for colour and THMs, and concern about the stability of residual chlorine and potential biogrowth in water supply pipework. This has led to several investigations (eg. in the UK, Sweden and the USA) of the benefits of applying ozonation prior to slow sand filtration in view of its known capability to decolorise humic substances and enhance biodegradability of the organic fractions. This paper summarises the experience to-date and highlights the benefits and problems that have been identified. Some studies have attempted to compare the relative performances of slow sand filters and granular activated carbon (GAC) filters for the removal of BDOC and the paper reviews the principal findings of these studies in view of the growing worldwide interest in the application of ozone-GAC. One major limitation with the use of ozone-GAC is the need periodically to remove and regenerate the carbon, since bed lives for the removal of humic substances are typically short. An alternative approach is to use inorganic adsorbents instead of carbon which have the potential to be chemically regenerated in-situ. The paper refers to the results of laboratory tests that have been carried out on the potential use of pre-ozonation followed by inorganic adsorbents (eg. Activated alumina, bauxite) for the removal of humic substances.

Integration of continuous biological and chemical (ozone) treatment of domestic wastewater: 1. Biodegradation and post-ozonation

The continuous treatment of domestic wastewater by an activated sludge process and by an integrated biological-chemical (ozone) oxidation process were studied in this work. Chemical oxygen demand (COD), biochemical oxygen demand (BOD), absorbance at 254nm (UV 254 ) and nitrogenous compound content were the parameters followed in order to evaluate the performance of the two processes. Experimental data showed that both UV 254 and COD reductions are improved in the combined biological-chemical oxidation procedure. Thus, reductions of 59.1% and 37.2% corresponding to COD and UV 254 , respectively were observed after the biological process (hydraulic retention time=5h; mixed liquor volatile suspended solids concentration=3142 g/m 3 ) compared with 71.0% and 78.4% obtained when a post-ozonation step (D O3 =41.7g/m 3 ) was included. During conventional activated sludge treatment, appropriate nitrification levels are only achieved with high hydraulic retention time and/or biomass concentration. Ozonation after the secondary treatment, however, allows improved nitrogen content reduction with total nitrite elimination. Post-ozonation also leads to a higher biodegradability of the treated wastewater. Thus, the ultimate BOD/COD ratio goes from 0.16 after biological oxidation to 0.34 after post-ozonation with 41.7 g O 3 /m 3 .

Electrical characteristics of high-quality sub-25-/spl Aring/ oxides grown by ultraviolet ozone exposure at low temperature

We have developed a method for controllably and reproducibly growing self-limiting ultrathin oxides with excellent electrical properties in the range /spl sim/10-25 /spl Aring/ thick at temperatures ranging from 25 to 600/spl deg/C, respectively, using an ultraviolet ozone (UVO/sub 3/) oxidation process. The self-limiting thickness depends primarily on the substrate temperature, allowing ultrathin oxide growth with precision and reproducibility using this UVO/sub 3/ process. Oxides grown by this method are comparable in electrical quality to thermal oxides, with similar leakage current densities and breakdown fields E/sub BD/>10 MV/cm. Current-voltage (I-V) analysis shows oxide thickness uniformity to within 1% from center to edge of a 4-in wafer. Capacitance-voltage (C-V) characterization of /spl sim/25 /spl Aring/ oxides shows excellent saturation behaviour, with low midgap interface trap densities and no hysteresis or dispersion.

Removal of humic substances by oxidation/biofiltration processes — A review

The paper is concerned principally with summarising the experience to-date of treating low alkalinity, low turbidity, humic-rich surface waters by the combination of ozone oxidation and biological filtration processes. In the UK, USA and other countries, upland coloured waters have often been treated by slow sand filtration in which only moderate removals of DOC have been achieved ( in-situ . The paper refers to the results of laboratory tests that have been carried out on the potential use of pre-ozonation followed by inorganic adsorbents (eg. Activated alumina, bauxite) for the removal of humic substances.

XPS and SIMS Study of Anhydrous HF and UV/Ozone‐Modified Silicon (100) Surfaces

X‐ray photoelectron spectroscopy and secondary ion mass spectrometry are used to study the surface chemistry of silicon single‐crystal wafers. Anhydrous and UV/ozone processes modify the surface chemistry by altering the concentration and bonding environments of the most abundant surface atoms: Si, O, C, H, and F. Anhydrous in conjunction with water vapor removes the silicon native oxide. Native oxides with initial thicknesses of 11Å, four monolayers, are exposed to a rinse, , and an aqueous rinse and are reduced to 0.4, 0.2, and 0.1 monolayers, respectively. The carbon concentration exhibits an inverse relationship with the submonolayer oxide coverage. The process results in less than a monolayer of silicon fluorides. The silicon fluoride species decrease with air exposure resulting in mostly oxyfluorides after 1h. Rinsing the fluorinated surface with reduces the fluorine concentration, removes trace metal impurities initially bonded to the native oxide, and promotes initial formation. UV/ozone exposure reduces the hydrocarbon concentration on the surface while producing 8Å, three monolayers, of . Exposing the surface to UV/ozone removes the silicon fluoride species; only oxyfluorides are observed with the ozone‐induced. The cleanest silicon surface with respect to metallic and hydrocarbon impurities was achieved with a rinse‐UV/ozone oxidation process.