Application of Ozone in Combined Processes

The previous chapters in Part B have dealt with the basics of the ozonation process. As seen in the discussion of full-scale ozonation applications (Chapter A 3), ozone is rarely used alone. The combination of ozone with other water treatment processes can often greatly increase effectiveness and cost efficiency of ozonation, or the addition of ozonation to an existing production process can increase efficiency in achieving production goals. Process combinations make sense that utilize ozone s effectiveness in  

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This entry introduces applications of ozone technology in various areas water and wastewater treatment control of the microbial safety of food decontamination of soils polymer surface modification and bleaching paper pulps. For water and wastewater treatment, in addition to being used alone, ozone is increasingly used in combination with heterogenous catalysts, UV/H2O2 (advanced oxidation process), and biological treatment to enhance ozonation efficiency. The discussion that follows mainly introduces the applications of ozone in water and wastewater treatment because ozone has been both extensively and intensively used in this area however, it does briefly describe other applications. 

An example where all four areas are utilized in combination with production processes is found in ozone applications in the semiconductor industry (Section B 6.1). Part of ozone s effectiveness in these four areas is derived from its production of OH-radicals. Combined processes, i. e. advanced oxidation processes, represent alternative techniques for catalyzing the production of these radicals and expands the range of compounds treatable with ozone (Section B 6.2). 

Ozone has been applied successfully and extensively for water and wastewater treatment. Ozone also has been used as a safe and effective antimicrobial agent in many food applications. Other applications of ozone include soil decontamination, polymer surface modification, and bleaching paper pulps. It is recognized that for water treatment, the combined use of ozone with either biological treatment, or heterogenous catalysts, or UV and/or H2O2 makes the whole process more efficient. 

Overview), but also information on how to set-up experiments so that they produce results that can be interpreted and extrapolated (Part B Ozone Applied). The experimenter is provided with tools to improve his or her results and interpret results found in the literature. The required theoretical foundation is laid at the beginning of each chapter in Part B, compact and tailored to ozone, followed by practical aspects. References are made to important literature sources to help direct the reader wishing for more in-depth information. A discussion of applications combining ozone with other processes illustrates how the oxidizing potential of ozone can be utilized. 

Modeling in drinking water applications is largely confined to describing chemical processes. The mathematical models used in this area are based on the reaction rate equation to describe the oxidation of the pollutants, combined with material balances on the reaction system to calculate the concentrations of the oxidants as a function of the water matrix. As noted above, the reaction rate equation is usually simplified to pseudo-first order. This is based on the assumption of steady-state concentrations for ozone and the radicals involved in the indirect reaction. 

Measurement of toxicity (biological analyses) The development of toxicity during chemical/biological treatment of waste waters was seldom assessed. Only in the last few years has the application of toxicity testing been reported more frequently (e. g. Diehl et al., 1995 Moerman et al., 1994 Jochimsen, 1997 Sosath, 1999). Moerman etal. (1994) showed that a toxicity balance around the whole process is important for combined chemical/biological treatment. It is not sufficient to assess the effect of ozonation alone (cf. chapter A 1). 

The treatment of s-triazine herbicides constitutes a clear application of the combined use of ozone and hydrogen peroxide. At the end of the eighties, this system was investigated to remove triazines in several pilot plants in France and the United Kingdom [228], The successful results obtained led to the implementation of this system in some water-treatment plants, such as those owned by the Compagnie Generale des Eaux in Paris [228], Since then, the 03/H202system has been used in many waterworks to improve the removal of. v-triazines. It should be noted, however, that ozone processes may not be appropriate for the removal of herbicides from water because of the potential formation of very low concentrations of harmful intermediates. 

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