Showing papers in "Ozone-science & Engineering in 1987"
TL;DR: In this article, the theoretical and practical yield of OH from O3 at high pH, 03/H202, O3/UV and H2O2/UV systems are reviewed.
Abstract: Advanced oxidation processes are defined as those which involve the generation of hydroxyl radicals in sufficient quantity to affect water purification. The theoretical and (practical yield of OH from O3 at high pH, 03/H202, O3/UV and H2O2/UV systems is reviewed. New data is presented which illustrates the importance of direct photolysis in the O3/UV process, the effect of the H202:03 ratio in the O3/H2O2 process, and the impact of the low extinction coefficient of H2O2 in the H202/UV process.
1,663 citations
TL;DR: In this paper, the disadvantage of chlorination of drinking water is the possible synthesis of toxic chlorinated fragments, and in different cases UV can be an alternative to chlorination, in which the germicidal effectivenes...
Abstract: The disadvantage of chlorination of drinking water is the possible synthesis of toxic chlorinated fragments. In different cases UV can be an alternative to chlorination. The germicidal effectivenes...
71 citations
TL;DR: Moreovoer et al. as mentioned in this paper studied the reactivities of four heterocyclic nitrogen compounds, at slightly acidic pH in a heterogeneous gas-liquid system, and found that the reactionivities of these compounds are different.
Abstract: Study of the ozonation of aqueous solutions of four heterocyclic nitrogen compounds, at slightly acidic pH in a heterogeneous gas-liquid system, showed that the reactivities of these compounds are different. Amitrole, a five-membered ring heterocycle, has been found to be a highly reactive compound, while atrazine, a six-membered ring heterocycle, has been found to be a poorly reactive compound. The benzotriazoles, benz-fused five-membered ring heterocycles, present intermediate reactivities. Moreovoer, the chemical natures of the ozonation by-products have been found to be different between amitrole and atrazine. With atrazine, ozone did not open the heterocyclic ring, and led to the formation of a trioxotriazine. With amitrole, ozone broke the heterocyclic ring and formed mainly formamide.
63 citations
TL;DR: In this paper, infrared absorption spectroscopy was used to identify and measure different nitrogen oxide species in the output of air-fed ozone generators, and the concentrations of nitrous oxide (N2O) and dinitrogen pentoxide (D2O5) were determined over a wide parameter range of modern high power medium frequency ozone generators.
Abstract: Infrared absorption spectroscopy is utilized to identify and measure different nitrogen oxide species in the output of air-fed ozone generators. The concentrations of nitrous oxide (N2O) and dinitrogen pentoxide (N2O5) were determined over a wide parameter range of modern high power medium-frequency ozone generators. With a typical ozonation dose of 1 mg ozone per liter of drinking water, less than 10 ug N2O and about 20 ug N205 are introduced into one liter of drinking water.
63 citations
TL;DR: The first order ozone attack on synthetic organic dyes has been investigated in this paper, showing that from one to four millimoles per liter of ozone was sufficient to attain a 5O% reduction in the concentration of all dyes during first order ozonations.
Abstract: Synthetic organic dyes were decomposed rapidly by ozone. The dyes all adhered well to first order kinetics with the exception of the Direct Yellow 12 which showed an initial zero order phase at pH 5. This has been tentatively ascribed to attack by unhydrolyzed ozone on the ethylenlc double bond. From one to four millimoles per liter of ozone was sufficient to attain a 5O% reduction in the concentration of all dyes during the first order ozonations.
58 citations
TL;DR: In this article, the feasibility of photochemical generation of ozone by irradiating gases containing oxygen with Hg lamps of the highest performance emitting the 185 nm line was investigated, and determining factors for practical yields in ozone generation by the 185nm wavelength are : the reactor and gas temperature, the reactor geometry, and the gas composition, as well as the pressure.
Abstract: This paper reflects an investigation of the feasibility of photochemical generation of ozone by irradiating gases containing oxygen with Hg lamps of the highest performance emitting the 185 nm line. Besides the expected photostationary equilibrium, determining factors for practical yields in ozone generation by the 185 nm wavelength are : the reactor and gas temperature, the reactor geometry, and the gas composition, as well as the pressure. Further developments are expected in the field of lamp construction and also improvement of reactor geometry. A better knowledge of the aging of the lamps is required, as well as of the photochemical reactions of oxygen in the technologies applied. Systems presently available are most promising for application on small scale or in areas of public water distribution which have no developed structure.
42 citations
TL;DR: Ozone transfer into potable water was studied in a commercial scale contactor as discussed by the authors, where ozone mass balances were calculated to determine ozone utilization in the contactor, as well as gas and liquid flow rates.
Abstract: Ozone transfer into potable water was studied in a commercial scale contactor. Ozone mass balances have been calculated to determine ozone utilization in the contactor. Gas and liquid flowrates, as...
28 citations
TL;DR: In this paper, the mass transfer of ozone absorbed by water in a semi-comtinuous stirred reactor is studied at the lab scale, and a complete factorial scheme is used to investigate the effect of agitation speed and gas flow.
Abstract: Mass Transfer of ozone absorbed by water in a semi-comtinuous stirred reactor is studied at the lab scale. Experimental investigation using a complete factorial scheme shows a predominant effect of agitation speed and gas flow and results in a correlation for the mass transfer coefficient, k1a. Solubility of ozone in water is estimated by evaluation of an apparent Henry's law constant for different temperatures (20* and 50*C), pH values (2 and 7) and a t constant ionic strength (0.13).
26 citations
TL;DR: It is clearly demonstrated that F–specific bacteriophages are better indicator organisms with regard to viral inactivation by UV than classical parameters like E. coli and fecal streptococcior coliphages.
Abstract: Secondary effluent was irradiated with UV in a shallow bed reactor at flow rates between 10 and 30 m3. h-1 using 1–3 high pressure mercury lamps. UV doses were calculated to range between 2.5 and 25 mJ.cm−2 and inactivation of four groups of microorganisms was measured: E. noli, fecal streptococci, somatic coliphagesi and F–specific bacteriophages. Their relative UV resistance (in this order) was 1.0 : 1.5 : 1.1 : 2.3. Inactivation of F–specific (coliphages with 3 log10 units required a dose of approx. 36 mJ.cm−2. Dose–response curves were linear with correlation coefficients of ca. 0.90, except for somatic coliphages, which seem to include a relatively UV–sensitive and a more resistant fraction. This study clearly demonstrated that F–specific bacteriophages are better indicator organisms with regard to viral inactivation by UV than classical parameters like E. coli. fecal streptococcior coliphages.
24 citations
TL;DR: In this article, the ozone and UV rays can lead to high level oxidation of the ozone-refractory organics, and the main parameters affecting the efficiency of the O3/UV system are: the ozonation rate, the average UV radiation intensity, the pH measurement, alkalinity and the type of compound to be oxidized.
Abstract: When treating natural water, the simultaneous use of ozone and UV rays can lead to high level oxidation of the ozone–refractory organics. The main parameters affecting the efficiency of the O3/UV system are: the ozonation rate, the average UV radiation intensity, the pH measurement, alkalinity, and the type of compound to be oxidized. In optimum Ou/UV system application conditions, the abatement of COD in water from the Seine river is never above 30%. On the other hand, TOC removal is increased in weakly carbonated pond water loaded with humic matter. The O3/UV system also ensures oxidation of saturated volatile organic halogens, with the exception of carbon tetrachloride.
21 citations
TL;DR: Controlled, pilot-plant ozone treatment tests were conducted on twenty-nine volatile organic contaminants in distilled water and groundwater as mentioned in this paper, and the results showed that aromatic compounds and alkenes are well removed by ozone treatment, but that alkanes are poorly removed.
Abstract: Controlled, pilot-plant ozone treatment tests were conducted on twenty-nine volatile organic contaminants in distilled water and groundwater. Results show that aromatic compounds and alkenes are well removed by ozone treatment, but that alkanes are poorly removed. Also, efficiency of destruction improved for the alkenes and aromatic compounds with increasing applied ozone dosage and, for some alkanes, with increasing pH. For most compounds, the efficacy of ozone was not severely affected by the background water matrix. Generally, information gathered from the literature regarding rate constants for the ozone treatment of compounds in the gaseous phase or in organic solution predicted, to a useful degree, the effectiveness of ozone in treating aqueous solutions in the present study. Several of the test conditions selected for this preliminary study may be similar to those found in drinking water treatment plants. Consequently the findings of this research may help guide utilities in their choice o...
TL;DR: In this article, organic contaminants dissolved in deionized pretreated and raw mains water were reacted with ultraviolet light and ozone Ozone first was used for partial oxidation followed by ozone combined with ultraviolet radiation to produce total oxidation The reduction of TOC level and direct oxidation of halogenated compounds were measured throughout the treatment process.
Abstract: Organic contaminants dissolved in deionized pretreated and raw mains water were reacted with ultraviolet light and ozone Ozone first was used for partial oxidation followed by ozone combined with ultraviolet radiation to produce total oxidation The reduction of TOC level and direct oxidation of halogenated compounds were measured throughout the treatment process The rate of TOC reduction was compared for ozone injected upstream and inside the reactor
TL;DR: In an aqueous solution of the water-soluble constituents of kerosene, naphthalenes were destroyed more quickly by ozone than alkylbenzenes at both pH 5 and pH 9.
Abstract: In an aqueous solution of the water-soluble constituents of kerosene, naphthalenes were destroyed more quickly by ozone than alkylbenzenes at both pH 5 and pH 9. When a kerosene surface film was ozonized, selective attack on aromatic relative to aliphatic hydrocarbon constituents occurred. Alkylbenzoic acids were the major products. Other oxygenated products (aldehydes, alcohols, peroxides) also were detected at lower concentrations. When ozonized separately, naphthalene reacted to form 2-formylcinnamaldehyde, 1-methylnaphthalene produced methylated isomers of 2-formylcinnamaldehyde, and tetrahydronaphthalene formed 1-tetralone.
TL;DR: In this paper, the ozonation of glyoxylic acid in aqueous solution is investigated in semicontinuous and continuous reacting systems to follow the evolution of both chemical products and kinetics.
Abstract: The ozonation of glyoxylic acid in aqueous solution is investigated in semicontinuous and continuous reacting systems to follow the evolution of both chemical products and kinetics. Evidence is given of formation of small amounts of formic acid and -of the promoting effect of peroxidic intermediates upon oxalic acid ozonation. Kinetic results indicate that the ozonation process develops according to a radical chain mechanism initiated by ozone attack on glyoxylic acid.
TL;DR: In this paper, the first electronic excited state of ozone (triplet state) was shown to be formed and destroyed in the cold plasma, and the ozone molecule formed in this state was then destroyed.
Abstract: Air or pure oxygen flowing into the discharge gap of a cold plasma reactor is the primary method for ozone production on commercial scale. The modelling of the conversion of oxygen into ozone has been set up by means of a kinetic scheme in which opposite reactions are considered. The forward reaction occurs via electronic activation, while the reverse reaction is temperature-dependent. Experimental results are in accord with this scheme, and lead to the following primary conclusions: the plasma temperature is a linear function of the applied power, while isothermal operation is the better from an economic point of view. The ozone molecule formed and destroyed in the cold plasma is suggested to be i.e., the first electronic excited state of ozone (triplet state).
TL;DR: The first order rate constants for these reactions were found to correlate excellently with the Hammett Polar Constant for a series of substituted phenols and pyrimidines.
Abstract: The kinetics of the heterogeneous ozonation of o, p-activated aromatic organic compounds have been correlated with structural parameters defined by Linear Free Energy Relationships. The gross first order rate constants for these reactions were found to correlate excellently with the Hammett Polar Constant for a series of substituted phenols and pyrimidines. Strong correlation also was obtained for the kinetics of ozonation of an homologous series of 2-alkyl-4,6-dinitrophenols and the Steric Parameter. The reaction rate was observed to increase as the electron density in the ring increased and decreased with increasing size of the substituent alkyl group. A preliminary model structured around the kinetics of a gas diffusion controlled reaction with infinitely fast chemical kinetics has been proposed along with a program of research to evaluate such a model.
TL;DR: In this paper, the authors found that initial ozone dose-time had a significant impact on reaction order, and that ozone solutions dosed initially for less than one minute displayed uniform second-order kinetics.
Abstract: AbstractDecomposition of ozone in dilute aqueous solutions was found to be a complex process kinetically. Initial ozone dose-time had a significant impact on reaction order. Solutions dosed initially for less than one minute displayed uniform second-order kinetics. For doses applied over 5 and 15 min periods at a pH -2, reaction order changed from 2 to 1 to 0 as ozone decomposition progressed. At a pH of 6.65, the transition was from a reaction order of 2.5-3 to 2. This behavior has been ascribed to the effect of accumulated ozone decomposition products on the decomposition process.
TL;DR: In this paper, pilot plant studies were carried out on the effect of ozone on the chemical content of a secondary domestic and industrial sewage, expressed in terms of COD, BOD5, nitrite ion concentrations, bacterial counts, XAD-4-extraetable compounds, and free amino acid concentrations.
Abstract: Pilot plant studies were carried out on the effect of ozone on the chemical content of a secondary domestic and industrial sewage. Results are expressed in terms of COD, BOD5, nitrite ion concentrations, bacterial counts, XAD-4-extraetable compounds, and free amino acid concentrations. Ozone dosages of 6 to 12 mg/L were found to reduce levels of fecal bacteria, COD and nitrite ion concentrations significantly, to modify the nature and the concentration of XAD-4-extraetable compounds, and to increase the concentration of free amino acids.
TL;DR: Starting in the early 1970s, the application of ozone for drinking water treatment began to evolve from primarily single-purpose, single-stage use for disinfection, taste and odor control or iron and manganese oxidation, to multipurpose uses of ozone as discussed by the authors.
Abstract: Starting in the early 1970s, the application of ozone for drinking water treatment began to evolve from primarily single-purpose, single-stage use for disinfection, taste and odor control or iron and manganese oxidation, to multipurpose uses of ozone. As a result, most of the newer drinking water treatment plants have installed two- and even three-stages of ozonation. in order to maximize the technological benefits of ozone and to minimize the costs involved.
TL;DR: In this paper, the authors compared the performance of the downflow bubble column with other gas/liquid contactors and showed that higher mass transfer areas can be obtained than, for example, in a bottom-sparged bubble column or in a loop-type reactor in the region of high liquid throughput.
Abstract: During the development of the downflow bubble column, knowledge of the specific interfacial area was a precondition for assessing the mass transfer performance. A comparison with other gas/liquid contactors shows that, in the downflow bubble column, higher mass transfer areas can be obtained than, for example, in a bottom-sparged bubble column or in a loop-type reactor in the region of high liquid throughputs. Examples for practical performance of downflow bubble columns are given, based on the derived correlations.
TL;DR: In this article, the influence of polysaccharides on survival of the capsulated K54 A3 and non-capsulated K 54 A3 (0) strains of Klebsiella aerogenes exposed to ozone was investigated.
Abstract: The influence of polysaccharides on survival of the capsulated K54 A3 and non-capsulated K54 A3 (0) strains of Klebsiella aerogenes exposed to ozone was investigated. Because it had been shown in this work that bacteria lose approximately half of their polysaccharides when suspended in water, all bacterial assays were performed using exactly the same medium surrounding the cells, so as to create the same ozone demand. Sensitivity of both strains A3 and A3(0) to ozone as tested in the laboratory was not significantly different, although the amount of exopolysaccharides adhering to the cells were five-fold greater with A3 than with A3(0).
TL;DR: Tests conducted with a pilot scale ozone system to control the infective stage of the fish Pathogen Ceratomvya shasta found the minimum effective ozone dose to be a CT value (ozone residual x minutes of retention) of 1.23.
Abstract: Tests conducted with a pilot scale ozone system to control the infective stage of the fish Pathogen Ceratomvya shasta found the minimum effective ozone dose to be a CT value (ozone residual x minutes of retention) of 1.23. Mortality of summer steelhead reared to, term on ozonated and raw river water was 1.4% and 81.2% permil; respectively. Test fish were significantly larger at the end of the rearing period. A full production system for the hatchery has been recommended.
TL;DR: In this article, the authors present several mathematical models which can be utilized in lieu of expensive pilot-scale analysis to determine the necessary conditions in order to optimize mass transfer coefficients in ozone contacting systems.
Abstract: The use of ozonation processes, in water treatment practice, has been reported to result in many beneficial effects. Low ozone partial pressures available from commercial generators make efficient ozone mass transfer into the aqueous phase imperative. This paper presents several mathematical models which can be utilized in lieu of expensive pilot-scale analysis to determine the necessary conditions in order to optimize mass transfer coefficients in ozone contacting systems.
TL;DR: In this article, the authors show that ozone can be produced in concentrations up to 3.5 wtJ (12 g/Nm3) in air and 7 wt% (92 g/nm3), with simultaneously low specific energy consumption.
Abstract: Today ozone can be produced in concentrations up to 3.5 wtJ (12 g/Nm3) in air and 7 wt% (92 g/Nm3) in oxygen with simultaneously low specific energy consumption. The high concentrations improve the transfer efficiency and the reaction kinetics of ozone. This is demonstrated with reference to the design basis of the water treatment plants of Los Angeles, Dordrecht and Jeddah. In all cases the overall costs per kilogram of ozone are minimized by choosing the appropriate ozone concentration between 2 wt% (24 g/Nm3) and 6 wt% (79 g/Nm3).
TL;DR: With a sufficient dose of ozone and activated carbon adsorption, the initial cytotoxicity of the raw water and the mutagenic or promoter activity are destroyed.
Abstract: Studies were carried out on-site in a potable water production plant utilizing ozonation treatment at three stages of the process. The quality of water in the treatment line was studied by chemical analysis, but also for toxicity to Hela cells after XAD resin concentration, and for mutagenesis to Salmonella Ames strains and mammalian cells V79 HGPRT system. With a sufficient dose of ozone and activated carbon adsorption, the initial cytotoxicity of the raw water and the mutagenic or promoter activity are destroyed.
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