Impact of Ozonation on Naphthenic Acids Speciation and Toxicity of Oil Sands Process-Affected Water to Vibrio fischeri and Mammalian Immune System (original) (raw)
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Characterization of raw water for the ozone application measuring ozone consumption rate
Water Research, 2001
Abstract}This study was conducted to illustrate an ideal method for characterizing natural waters for ozonation processes in drinking water treatment plants. A specific instrument designed with the flow injection analysis (FIA) technique enabled us to measure accurately the ozone decomposition rate, which was found to consist of two stages: the instantaneous ozone consumption stage and the slower ozone decay stage. The ozone consumption rate was measured at the initial and secondary stages by determining certain parameters called the instantaneous ozone demand (ID) and the pseudo first-order decay rate constant (k c ). Using the OHd-probe, the yield of OHd per consumed ozone was also measured to determine its potential to produce OHd for the oxidation of micropollutants during the ozonation process. The ozone consumption of the ID values was significant in most natural waters, and substantial amounts of OHd were found to generate during the instantaneous ozone consumption stage. This study also investigated the effects of particulates, ozone doses, and sequential ozone injection on ozone decomposition kinetics and OHd formation yield. #
Methodology Of Ozone Introduction Into Water And Wastewater Treatment
Ozone: Science & Engineering, 1993
Theoretical basis and methodology for calculation and modeling of ozonation processes and contact equipment have been elaborated. Methodology of determination of reaction rate constant, stoichiometric coefficient, optimum values of pH, intermediate and final products, regimes of chemisorption, etc., for certain typical fast and slow reacting organic compounds (aniline, toluidine, humic acids, nitrobenzene, glyoxalic, oxalic and acetic acid) and wastewaters have been proposed. For calculation of the wastewater ozonation process, the value of chemical oxygen demand (COD) was suggested to be as a kinetic parameter from the solution side. On the basis of kinetic information, recommendations for the choice of the construction of contact equipment for the different chemisorption regimes of ozonation have been presented. Some new contact apparatuses have been proposed.
ENVIRONMENTAL …, 2008
During recent years, surface water resources supplying Tehran's potable water-Karaj, Lar and Jajrood Rivers-are contaminated with different microorganisms due to population growth. Additionally, the amount of organic materials generating odor, taste and color in the surface water has increased sharply. By considering the trihalomethane (THM) production potential of dissolved chlorine in reaction with innocuous humic substances, future use of chlorine as a disinfectant in Tehran's drinking water is clouded in uncertainty. Accordingly, the use of ozone as another alternative was taken in to consideration for disinfection of drinking water in this mega city. In order to evaluate advantages and disadvantages of water ozonation a pilot with a generating capacity of 4 gr ozone per hour was designed. This study was performed between April and September 2005 and Tehran Pars water treatment plant in the Northeast of Tehran was chosen for the case study. Bacteria removal was considered to be at highest level in all monthly samples. Different ozone contact times and dosages were tested in the deactivation of nematodes and the results showed the perfect removal in specified periods. Although the initial investment for construction and implementation of the required apparatuses is relatively high, since the raw material for ozone generation is air, the use of ozone is financially justifiable during the predicted time of operation. Moreover, the transfer and storage of ozone is much easier in comparison with chlorine which is currently in use. Unlike chlorine, the use of ozone as a disinfectant does not have the potential of THMs generation. On the other hand, ozone must be generated on site and is instable in water. Therefore, a continuous and precise monitoring and maintenance process must be taken in to consideration. Furthermore, due to high corrosive potential of ozone, special resistant materials must be used in the applied instruments.
Ozone disinfection: main parameters for process design in wastewater treatment and reuse
Wastewater disinfection by ozone was investigated at pilot and full scale on different wastewater effluents and two types of ozone reactors. It was demonstrated that water quality and, in particular, suspended solids and organic content strongly influence the required ozone dose for a given level of disinfection. The increase in contact time and residual ozone concentration did not improve the log removal of viruses and bacteria. However, the 'Ct' approach, commonly applied in drinking water treatment can be used for wastewater ozonation, if a sufficient ozone dose can be transferred to the effluent resulting in an ozone residual which can be measured. These considerations should be taken into account for the improved design of ozonation facilities. It should be underlined that short contact times are only possible if fast balanced distribution of the ozone dose is achieved as rapidly as possible, in order to satisfy fast chemical reactions (colloidal matter destabilisation, zeta potential, etc.) and enable a uniform distributed ozone residual for the slower reactions (disinfection, oxidation of micropollutants, etc.).
Chemical Engineering Science, 2011
Foreseen standards regarding microorganism content for drinking water require assessment of the capability of existing plants to reach the upcoming requirements. This paper presents the development of a tool to assess this capability in a commonly encountered key step of water disinfection: ozonation. In this paper, this tool is applied to the test case of an ozonation channel of the Belgian drinking water producer Vivaqua. This tool is based on a mathematical model of the momentum and mass transport phenomena in an ozonation channel. The gas–liquid flow is coupled to ozone mass transfer and kinetics describing the ozone and microorganisms concentrations decay. The degradation of Bacillus subtilis spores, as a representative of resistant microorganisms, is implemented in the model. The model takes explicitly into account the bubble size variation and its impact on mass transfer. Bubbles sizes and kinetics parameters are estimated based on dedicated experiments. The model is partially validated by comparing simulations results, obtained using computational fluid dynamics, to experimental residence time distributions, residual ozone concentration and Bacillus subtilis spores degradation efficiency measurements obtained on the studied ozonation channel. It is shown that, at the industrial scale, bubble diameter variation has a significant impact on ozone concentration in the liquid at the reactor exit. Using the tool, it is also shown that, the ozonation channel of Vivaqua can be used to achieve degradation of resistant microorganisms but only with its maximal flow rate and concentration of ozone injection. Moreover, at low operating temperature, some microorganisms that present latency towards reaction with dissolved ozone might hardly be destroyed.
Applications of ozone for modern wastewater treatment
International Journal of Environmental Engineering, 2012
Modern Wastewater Treatment Plants (WWTPs) effi ciently eliminate organic pollution down to Biological Oxygen Demand (BOD) and Suspended Solids (SS) values of less than 30 mg/l. However, these treated effl uents still contain biologically Persistent Organic Matter (POM), characterised by a Chemical Oxygen Demand (COD) of between 50 and more than 100 mg/l. Industrial WWTP effl uents have COD concentrations of several hundred mg/l. Under certain conditions of discharge imposed to the effl uent, POM abatement is necessary. Elimination of pathogenic microorganisms , i.e., disinfection and inhibition of acute toxicity, is also required. Another class of toxic compounds, Micro-Pollutants (MPs), present in WWTP effl uents in much lower concentrations, μg/l even ng/l, has become a serious matter of concern. Ozonation, as a complementary stage in the treatment sequence of a WWTP, alone or in combination with biofi ltration, has been demonstrated by multiple laboratory-pilot tests and existing operating plants to be an effi cient and economically sound technology for the abatement of and POM and MPs and for disinfection. The purpose of this essay is to present ozone with its state-of-the-art features, from a qualitative as well as a quantitative aspect, with examples of modern applications for improved wastewater treatment.
Wastewater disinfection by ozone
Wastewater disinfection by ozone was investigated at pilot scale on different wastewater effluents. Variations in operating conditions showed that a very low hydraulic retention time (2 min) was sufficient for efficient fecal coliform inactivation, provided a sufficient ozone dose was transferred to the effluent. Therefore, the transferred ozone dose appeared to be the critical parameter for the design of wastewater disinfection. As a consequence, the ''Ct'' approach commonly applied in drinking water treatment should not be used for wastewater ozonation. Design parameters of ozonation were proposed for two types of regulations, and for effluents of different qualities. It was demonstrated that only with an efficient filtration step one can meet stringent standards such as the California Title 22 criteria. In all cases, viruses were totally inactivated; consequently, viruses do not constitute a limiting factor in wastewater disinfection by ozone.
Water Research, 2006
Hydroxyl radicals AOP Ozone demand Quench-flow system Kinetics Disinfection Pharmaceuticals Wastewater Drinking water A B S T R A C T Due to a lack of adequate experimental techniques, the kinetics of the first 20 s of ozone decomposition in natural water and wastewater is still poorly understood. Introducing a continuous quench-flow system (CQFS), measurements starting 350 ms after ozone addition are presented for the first time. Very high HO d to O 3 exposures ratios (R ct ¼ R HO d dt/ R O 3 dt) reveal that the first 20 s of ozonation present oxidation conditions that are similar to ozone-based advanced oxidation processes (AOP). The oxidation of carbamazepine could be accurately modeled using O 3 and HO d exposures measured with CQFS during wastewater ozonation. These results demonstrate the applicability of bench scale determined second-order rate constants for wastewater ozonation. Important degrees of pharmaceutical oxidation and microbial inactivation are predicted, indicating