Improvement of the Ozonation Process Through the Use of Static Mixers

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Among the known disinfectants, ozone has been demonstrated to be very effective in inactivating protozoans. Current and proposed regulations impose additional treatment requirements for Cryptosporidium parvum . These regulatory trends tend to place more stringent performance demands on disinfection systems and have therefore increased the need for improvements in the design. The static mixer offers one alternative method for improving the efficiency of the dissolution of ozone and optimizing its use in the disinfection process. The overall objective of this research was to quantify the potential benefits of ozone application through the use of static mixers in terms of increased transfer efficiency, disinfection capacity, and enhanced chemical reactions at laboratory-, pilot-, and full-scale systems. Specific goals were to identify and quantify the effect of several water quality parameters and environmental/engineered factors on the disinfection capacity of the ozone-static mixer system and assess bromate formation under optimum conditions for microbial inactivation. The results showed that a static mixer provided (1) rapid and efficient dissolution of gaseous ozone and (2) generation of a homogeneous dissolved ozone solution. These conditions led to higher CTs resulting in enhanced inactivation as compared to fine bubble diffusion contactors. It was found that a static mixer, when integrated with a well-designed, continuous-plug flow ozone contactor, could achieve excellent and predictable Cryptosporidium parvum inactivation. In such systems, applying low ozone doses (£ 0.5 mg O3/mg C) combined with a pH of £ 7.0 can provide adequate microbial inactivation while keeping bromate formation below the current MCL (10 ppb. Originally published by AwwaRF for its subscribers in 2003 This publication can also be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below