Parameters that influence ozonation

Influent, effluent, and reactor concentrations - of ozone in the gas phase  

Other relevant water parameters c(initiator), c(scavenger), c(promoter) c(/) c(S), c(P), 

With these parameters we can set-up a mass balance on the system, which is the basis for evaluating the experimental results. The mass balance for the absorption (of any gas, e. g. ozone) in a continuous-flow stirred tank reactor (CFSTR) under the assumption that the gas and liquid phases are ideally mixed (cL = cLe, cG = cGe), are as follows  

Assuming that compound M is non-volatile and is not stripped (c(M) = c(M)e), the mass balance for M in the liquid phase is  

The calculated parameters necessary to evaluate the data and discuss the results are found in Table 1 -2. 

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This chapter will first provide some basics on ozone mass transfer, including theoretical background on the (two-) film theory of gas absorption and the definition of over-all mass transfer coefficients KLa (Section B 3.1) as well as an overview of the main parameters of influence (Section B 3.2). Empirical correction factors for mass transfer coefficients will also be presented in Section B 3.2. These basics will be followed by a description of the common methods for the determination of ozone mass transfer coefficients (Section B 3.3) including practical advice for the performance of the appropriate experiments. Emphasis is laid on the design of the experiments so that true mass transfer coefficients are obtained. 

Recently, bromate has become the most important inorganic oxyhalide by-product, and its concentration in drinking water has to be controlled. Furthermore, the subjects of interest and advanced research are chlorite and chlorate. Bromates are formed when water containing bromide is ozonated. The concentration of bromide in natural waters varies, typically, between 10 and 1000 p-g/L. From the theoretical and practical point of view, it can be seen that bromate formation can be influenced by many parameters, such as ozone dose, water pH, temperature, and indigenous concentration of bromide. ... 

Reaction kinetics describes what influences the reaction and how fast it takes place. Knowledge of kinetic parameters, such as reaction order n and reaction rate constant k, helps us to assess the feasibility of using ozonation to treat waters and to design an appropriate reactor system. It can help us to understand how a reaction can be influenced, so that a treatment process can be optimized. Kinetic parameters are also necessary for use in scientific models, with which we further improve our understanding of the chemical processes we are studying. 

Experimental studies have been used to predict reactor performance. Frye et al. (1958) used a substitute reaction of ozone decomposition to study hydrocarbon synthesis. The ozone decomposition can be run at low pressures and temperatures and can be rate controlled in the same way and by the same catalyst as the reaction under development. Frye and coworkers used three beds, 2, 8, and 30 inches in diameter to study the size influence. We should interject a caution that the use of pressures and temperatures diflferent from those of the actual reaction may mean that the hydrodynamics of the substitute reaction model will dilfer from the actual application this will be illustrated later in the chapter. Figure 1 shows the apparent reaction rate constant for the different bed diameters at two different bed heights, with the other parameters held constant. Note that the rate constant decreased by roughly a factor of 3 between the 2 inch and 30 inch beds. 

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