An Automated Procedure for Monitoring the Effectiveness of Ozonation Processes

Measurement of the 254 nm absorption of organics was chosen for monitoring the ozonation processes used to remove organic matter in a drinking water because of its ability to reflect the performance of ozonation. Ozone flow rate, ozone concentration in the gas (phase, addition of H₂0₂ and seasonal variations on kinetics of the reduction of UV absorption were varied and the efficiency of ozonation was determined. For several yearst ozonation has been applied at different points in potable water treatment. The original goal of ozonation was reduction in taste and odor and disinfection without by products of organoleptic concern (e.g.. chlorophenols). Ozone also has the capacity to oxidize organic matter.     

Ozone treatment of textile effluents and dyes: effect of applied ozone dose,pH and dye concentration

The ozonation of wastewater supplied from a treatment plant (Samples A and B) and dye‐bath effluent (Sample C) from a dyeing and finishing mill and acid dye solutions in a semi‐batch reactor has been examined to explore the impact of ozone dose, pH, and initial dye concentration. Results revealed that the apparent rate constants were raised with increases in applied ozone dose and pH, and decreases in initial dye concentration. While the color removal efficiencies of both wastewater Samples A and C for 15 min ozonation at high ozone dosage were 95 and 97%, respectively, these were 81 and 87%, respectively at low ozone dosage. The chemical oxygen demand (COD) and dissolved organic carbon (DOC) removal efficiencies at several ozone dose applications for a 15 min ozonation time were in the ranges of 15–46% and 10–20%, respectively for Sample A and 15–33% and 9–19% respectively for Sample C. Ozone consumption per unit color, COD and DOC removal at any time was found to be almost the same while the applied ozone dose was different. Ozonation could improve the BOD₅ (biological oxygen demand) COD ratio of Sample A by 1.6 times with 300 mg dm^?3 ozone consumption. Ozonation of acid dyes was a pseudo‐first order reaction with respect to dye. Increases in dye concentration increased specific ozone consumption. Specific ozone consumption for Acid Red 183 (AR‐183) dye solution with a concentration of 50 mg dm^?3 rose from 0.32 to 0.72 mg‐O₃ per mg dye decomposed as the dye concentration was increased to 500 mg dm^?3. © 2002 Society of Chemical Industry     

Effects Of Ozone On The Production Of Biodegradable Dissolved Organic Carbon (BDOC) During Water Treatment

This article deals with the oxidation effect of ozone on the increasing fraction of biodegradable organic matter with the “ozotest” method, a laboratory technique which simulates the effect of ozonation and allows a complete oxidation assessment. Ozone treatment was performed on river water samples and sand filter effluent samples. Ozone consumption, reduction of UV absorbance and BDOC formation were monitored with applied ozone doses from 0 to 10 mg/L and with contact times from 0 to 60 min. The BDOC formation was optimum at an applied ozone dose of 0.25-0.5 mg O₃ per mg DOC (contact time = 5 min) corresponding to apparition of traces of residual ozone and maximum UV reduction. Maximum ozone consumption, UV reduction and BDOC formation occurred simultaneously during the first two minutes of treatment. Concerning BDOC formation, applied ozone dose showed a greater effectiveness than contact time. For the same quantity of consumed ozone, a short contact time associated with a high ozone dose was preferable to a long contact time and a low ozone dose.     

Effect of stream segregation on ozonation for the removal of significant COD fractions from textile wastewater

Ozonation was tested on selected streams of cotton finishing textile plant wastewater for optimizing chemical oxygen demand (COD) removal. For this purpose, significant COD fractions in the wastewater were experimentally identified and the effect of ozone on these fractions was investigated. Ozonation experiments were performed with a 1 dm³ sample volume. Ozone treatment of batches of raw wastewater provided, at a rate of 62 mg min^?1 and a gas feeding time of 15 min, achieved complete colour removal but only 21% COD reduction. Increasing the feeding time to 30 min slightly increased the COD removal to 32%. At this feeding time, removal of the readily biodegradable COD was 60%, but soluble inert COD reduction remained at 16%, indicating selective preference of ozone for simpler compounds. At low concentrations, ozone was mainly influential on soluble COD compounds. Longer feeding times also affected particulate compounds, resulting in the solubilization of the COD fractions. Pre‐ozonation of the dye‐house wastewater, as a segregated stream, proved much more effective in the breakdown of refractory organic compounds, rendering the overall plant effluent more amenable to biological treatment. © 2002 Society of Chemical Industry     

Ozonation of the reactive dye intermediate 2‐naphthylamine 3,6,8‐trisulphonic acid (K‐Acid): kinetic assessment,ozonation products and ecotoxicity

Ozonation of the commercially important, recalcitrant reactive dye intermediate 2‐naphthylamine 3,6,8‐trisulphonic acid (K‐Acid) was investigated. Ozonation performance was examined by following ozone absorption rates and K‐Acid, chemical oxygen demand and total organic carbon removals. Mean oxidation states and unidentified organic products were also determined. At pH 3, where direct ozone reactions are dominant, the second‐order rate constant between K‐Acid and molecular ozone was determined as 20 m ^?1 s^?1 for steady‐state aqueous ozone concentration. The competition kinetics approach was also adopted where a reference compound, phenol, and K‐Acid were subjected to ozonation. By applying this method, the second‐order reaction rate constant was found to be 76 m ^?1 s^?1. Common oxidation products formed during ozonation at pH 3, pH 7 and pH 7 with 1 mm hydrogen peroxide were identified as methoxy‐phenyl‐oxime, phenol, benzene, benzaldehyde and oxalic acid via high‐performance liquid chromatography and gas chromatography/mass spectrometry analyses. Continuous nitrate and sulphate evolution were observed during K‐Acid ozonation as a consequence of the abrupt release and subsequent oxidation of its amino and sulphonate groups. The number and amount of reaction products were most intensive for K‐Acid ozonation at pH 7 with 1 mm hydrogen peroxide. According to the acute toxicity tests conducted with Vibrio fischeri, ozonation products were not less toxic than the original K‐Acid solution that caused only 15% inhibition.     

微纳米气泡臭氧高级氧化工艺处理电镀废水的中试

对江苏省某电镀园区污水厂尾水使用微纳米气泡臭氧高级氧化工艺进行深度处理中试研究,要求处理后达到《地表水环境质量标准》(GB 3838—2002)Ⅴ类标准.半连续流试验结果表明,单独臭氧氧化处理无法有效去除有机物,加入双氧水催化臭氧微纳米气泡处理后可以使COD达标.在臭氧与双氧水投加量摩尔比为2时,投加64.6 mg/L...     

Effects of Ozone on Resin Acids in Thermomechanical Pulp and Paper Mill Circulation Waters

The present study investigated ozonation as means to remove resin acids from pulp and paper mill circulation waters. Ozone selectively oxidizes resin acids in debarking, thermomechanical pulping (TMP), and newsprint machine (PM) circulation waters. The relative ozone dose of 0.2 mgO₃/initial mgCOD eliminated over 90% of total resin acid concentration in all tested waters, despite the initial resin acid or organic matter concentration. With that ozone dose, the removal of organic material (measured as COD) was only about 30%. Because of the different COD concentrations of tested waters, the absolute amount of ozone needed for over 90% resin acid reduction was 2000 mg/1 for debarking water, 600 mg/1 for TMP water, and 300 mg/1 for PM water, when initial COD concentrations were 10,000, 3000, and 1500 mg/1, respectively. In theory, abietane type resin acids should be more susceptible to ozone attack than pimarane type resin acids, because of their conjugated double bond structure. In the experiments, a high oxidizability of pimarane type resin acids, as compared to abietane type resin acids, was found.     

Enhancement in mineralization of some natural refractory organic compounds by ozonation–aerobic biodegradation

Two schemes, the first involving ozonation followed by final aerobic biodegradation (phase I experiments), and the second involving initial aerobic biodegradation, followed by ozonation and subsequent final aerobic biodegradation (phase II experiments), were examined for enhanced mineralization of refractory model compounds, viz. gallic acid, tannin and lignin. In all cases, and irrespective of the applied scheme, chemical oxygen demand (COD), total organic carbon (TOC), COD/TOC ratio, and specific UV absorbance at 280 nm attributed to the model compounds decreased with application of increasing ozone dose. The residual organic matter remaining after ozonation exhibited enhanced aerobic biodegradability in all cases. Further, in all cases and irrespective of the applied scheme, the overall amount of COD and TOC removed through the combination of ozonation and biodegradation processes increased with increase in ozone dose for all three model compounds, and more than 90% COD removal could be achieved with an ozone dose of 3 mg ozone absorbed per mg initial TOC, as compared with approximately 40% COD removal when no ozone was applied. Treatment by the first scheme resulted in the fraction of starting COD removed through biodegradation decreasing with increase in ozone dose in all cases, while this fraction increased or remained constant during treatment using the second scheme. In the case of tannin and lignin, similar overall COD removal could be achieved at lower ozone doses using scheme II. Due to incorporation of the initial aerobic biodegradation step in scheme II, the ozone requirement for additional mineralization, ie mineralization over and above that achieved by aerobic biodegradation, was also lower than that in scheme I. Copyright © 2005 Society of Chemical Industry     

Impact of ozonation on subsequent treatment of azo dye solutions

BACKGROUND: Aqueous solutions of four azo‐dyes, Acid Red 14 (AR14), Congo Red (CR), Reactive Black 5 (RB5), and Reactive Violet 5 (RV5) were treated with ozone, and the impact of ozonation on their subsequent treatability by aerobic biodegradation processes was investigated. RESULTS: In all cases, ozonation at the highest ozone doses investigated could remove more than 96% of the original dye, and the corresponding residual colour of the azo dye solutions declined to less than 20 on the Pt‐Co scale. Ozonation also resulted in reduction of chemical oxygen demand (COD), total organic carbon (TOC) the COD/TOC ratio and pH, while in all cases electrical conductivity of the dye solutions increased. Activity of the microbial colonies present in domestic wastewater was not inhibited when un‐ozonized solutions of these dyes were mixed in a 1:1 volumetric ratio with domestic wastewater, although the dyes themselves were not degraded. Also, no significant inhibition of microbial activity was observed in 1:1 mixtures of ozonized dye solutions and domestic wastewater, especially when the initial dye concentration was low and the applied ozone dose was high. In almost all cases, progressively enhanced BOD exertion was observed in mixtures containing dye solutions ozonized with progressively higher doses. This indicated that some ozonation by‐products of the above dyes could be degraded by microorganisms present in domestic wastewater. CONCLUSIONS: It was concluded that the above dye solutions, after ozonation for partial or complete colour removal, could be mixed with domestic wastewater for subsequent treatment by aerobic biological processes, with no adverse impact on the activity of the microbial colonies present in domestic wastewater. Copyright © 2007 Society of Chemical Industry     

Activated sludge process coupled with intermittent ozonation for sludge yield reduction and effluent water quality control

BACKGROUND: Ozone is applied in wastewater treatment for effluent water quality improvement (post‐ozonation) as well as for excess sludge reduction (in the recirculation line). There is some evidence that ozone dosed directly to aerobic biooxidation (ABO) process enhances degradation of recalcitrant compounds into intermediates, following their biodegradation in the same reactor. However, no information regarding the influence of ozone on sludge yield in this system was found. Therefore, the current work aimed to evaluate the effect of ozone on the sludge yield when ozone is dosed directly to the ABO process. In addition, batch and continuous treatment schemes for phenolic wastewater treatment are compared. RESULTS: The results revealed that an optimal ozone dose of ～30 mgO₃ L^?1 day^?1 reduced the sludge yield by ～50%, while effluent water quality in terms of total chemical oxygen demand (TCOD), compared with a conventional ABO process, was improved by 35.5 ± 3.6%. Slight improvement in soluble COD removal at the same ozone dose was also detected. The toxicity of effluent water was reduced as the ozone dose was increased. CONCLUSIONS: In an integrated ozonation‐ABO process it is possible to simultaneously reduce sludge yield and to improve effluent water quality, as COD and toxicity are reduced. Copyright © 2011 Society of Chemical Industry     

Ozone Sparging Closure of an Industrial VOC Spill Site Adjacent to a Water Supply Well Site

Ozone sparging using the KTI C-Sparge? process was performed on an industrial site adjacent to a major water supply well site. Ozone sparging was initiated in February, 2000, and groundwater volatile organic compound concentrations in downgradient wells decreased as much as 95 percent by the end of 2001. From 2003 to closure in 2006, the responsible party continued treatment with monitored attenuation and combined source treatment with a barrier region rather than more aggressively attack plant source areas. Initial remedial actions included source excavation (1996), a Fenton's Reagent flood (1998), followed by ozone sparging. The regulatory agency accepted ozone sparging for source treatment and temporary barrier as the most desirable alternative. Monitored attenuation was not acceptable without source reduction and elimination. Continued operation of the facility progressed during remedial treatment. Closure was obtained with the region achieving MCLs (Minimum Contaminant Levels) at the operational water supply wells and on the industrial site boundary. Final groundwater removal was in excess of 99%. No adverse water quality impacts were found during treatment at the water supply wellheads.     

Ozonation of black‐table‐olive industrial wastewaters: effect of an aerobic biological pretreatment

The present work is a study of oxidative degradation of the organic matter present in the washing waters from the black‐table‐olive industry. This oxidation is performed by an ozonation process, by an aerobic biological degradation process, and by another ozonation of biologically pretreated washing waters. In the ozonation process, a second‐order kinetic reaction with respect to ozone and COD or aromaticity has been deduced. The kinetic rate constants were correlated as a function of temperature by Arrhenius‐type equations. In the aerobic biological treatment, a kinetic study was performed using the Contois model, giving a value of 4.8 10⁻² h⁻¹ for the kinetic bioreaction constant. Likewise, a cell yield coefficient of 0.30 g VSS g COD⁻¹ and a kinetic constant for the endogenous metabolisme of 1.2 10⁻² h⁻¹ were deduced. Finally, in the ozonation of biologically pretreated wash‐waters, the deduced kinetic rate constants for COD and aromaticity were, respectively, 4.5 and 2.4 times higher that those corresponding to the ozonation of wash‐waters without biological pretreatment. © 2000 Society of Chemical Industry     

Determination of assimilable organic carbon (aoc) in ozonated water with acinetobacter calcoaceticus

The effect of ozone application in drinking water on the production of assimilable organic carbon (AOC) was evaluated. The typical procedure to determine AOC is suggested by van der Kooij, which is the method of bacterial growth measurement by colony‐forming units using the strain P17 and/or NOX. The bacterial indicator species used for this study is Acinetobacter calcoaceticus which was isolated and identified while ozonating Nakdong river water. This strain could never be isolated from the raw water, but this strain was the predominant isolate in the ozonated water. Within a short incubation time, this organism was found to replicate well on acetate and oxalate as the sole carbon sources. The yield coefficients of this organism for acetate and oxalate are the same order of magnitude as the value of P17 and NOX. With full‐scale experiments, A. calcoaceticus concentration was found to increase after ozonation, but did not decrease upon chlorination. In laboratory‐scale experiments with Yongsan river water, aldehyes were found to be produced in proportion to the ozone dose. The raw water contains low concentrations of aldehydes, but has a high AOC concentration. A correlation between aldehyde production and AOC production was observed in the tested water with ozonation.     

Disinfection of Seawater: Application of UV and Ozone

Ozone and ultraviolet technologies are proposed as potential disinfecting agents for seawater. Ozone doses were applied in the range 0.38 to 4.89 mg O₃ L^?1. They permit to observe a complete disinfection as well as UV doses superior to 320 J L^?1. Impacts of both processes on organic matter were also studied. UV absorbances were reduced in both cases but in higher proportion using ozone (up to 50% removal). Total organic carbon was slightly reduced by UV radiation, and ozonation achieves up to 10% mineralization. Ozone reaction proceeds with biochemical oxygen demand increase. Seawater ozonation, in addition, leads to the formation of residual oxidants that show an inhibitory effect on autochthonous microorganisms.     

Optimum Ozone Dosage of Preozonation and Characteristic Change of Refractory Organics in Landfill Leachate

Preozonation on landfill leachate was carried out. COD removal rate has an obvious inflection at ozone dosage 0.186 mg_O3/mg_COD in ozonation process. Seven sets of identical O₃-SBR combined process under different ozone dosages were studied. The results indicated that the best COD removal rate of synergetic effect is also at 0.186 mg_O3/mg_COD. New organic substances produced after ozonation was confirmed by an excitation-emission matrix (EEM). Carbon dioxide production increased from 36.3 mg to 75.7 mg after ozonation, confirming that biodegradability of refractory organics in landfill leachate was enhanced. All the arguments indicated that the inflection point of COD removal by ozonation has a great significance for preozonation.     

Kinetics of Organic Matter Removal in a Chemical Sequential Reactor (CSR)

The Chemical Sequential Reactor (CSR) can be considered as an advanced oxidation process able to treat wastewaters with ozone. Its operation involves a succession of acidic and alkaline pH conditions throughout continuous ozonation. The two oxidation mechanisms (direct reaction of molecular ozone and hydroxyl free radical reactions], coupled with carbon dioxide stripping, increase removal rates and ozone efficiency. Ozone efficiency is also maintained for longer periods.     

Diclofenac removal from water by ozone and photolytic TiO2 catalysed processes

BACKGROUND: The aim of this work was to establish the efficiency of single ozonation at different pH levels (5, 7 and 9) and with different TiO₂ photolytic oxidizing systems (O₂/UV‐A/TiO₂, O₃/UV‐A/TiO₂ or UV‐A/TiO₂) for diclofenac removal from water, with especial emphasis on mineralization of the organic matter. RESULTS: In the case of single ozonation processes, results show fast and practically complete elimination of diclofenac, with little differences in removal rates that depend on pH and buffering conditions. In contrast, total organic carbon (TOC) removal rates are slow and mineralization degree reaches 50% at best. As far as photocatalytic processes are concerned, diclofenac is completely removed from the aqueous solutions at high rates. However, unlike single ozonation processes, TOC removal can reach 80%. CONCLUSION: In single ozonation processes, direct ozone reaction is mainly responsible for diclofenac elimination. Once diclofenac has disappeared, its by‐products are removed by reaction with hydroxyl radicals formed in the ozone decomposition and also from the reaction of diclofenac with ozone. In the photocatalytic processes hydroxyl radicals are responsible oxidant species of diclofenac removal as well as by‐products. Copyright © 2010 Society of Chemical Industry     

Ozone Disinfection Of Urban Storm Drain Water

Concerns regarding bacteria in runoff entering Santa Monica Bay were validated by the isolation of human enteric virus in storm drain effluents. As an alternative to chlorination, ozonation was investigated for disinfection of dry-weather urban runoff. Ozone at 10-20 mg/L reduced coliform counts an average of 3.4-logs, with 6-log maximal disinfection. Although varying contaminant concentrations complicate the analyses, total organic carbon predicted ozone demand, and effluent coliform counts were correlated with ozone residuals.     

Chemical treatment of cork‐processing wastewaters for potential reuse

The chemical treatment of cork‐processing wastewater by ozonation, alone and in combination with hydrogen peroxide and UV radiation was investigated. A reduction of the chemical oxygen demand (COD) ranging from 42% to 76% was obtained during ozonation after 3 h of reaction, depending on the experimental conditions. The additional presence of hydrogen peroxide and UV radiation enhanced the efficiency of the ozonation treatment due to the contribution of the OH radicals formed in the decomposition of ozone. Thus, final reductions of the COD higher than 90% and a complete elimination of phenolic compounds and absorbance at 254 nm were achieved in both Advanced Oxidation Processes (AOPs), O₃/H₂O₂ and O₃/UV. Therefore the effluent resulting from the ozonation treatments can be reused in the cork‐processing industry. In a second step, the chemical treatment was conducted by means of UV radiation alone and by the action of hydroxyl radicals, which were generated by the following AOPs: UV/H₂O₂, Fenton's reagent, and photo‐Fenton system. The single photochemical process resulted in 9% of the organic matter present being removed, while the AOPs significantly enhanced this reduction with values in the range 20–75%. Kinetic studies for both groups of treatments were performed, and apparent kinetic rate constants were evaluated. In the ozone‐based experiments, the rate constants ranged from 1846 to 10922 dm³ mol^?1 O₃ h^?1, depending on the operating conditions. In the oxidation experiments using oxidants other than ozone, the rate constants varied between 0.06 and 1.19 h^?1. Copyright © 2004 Society of Chemical Industry