DEVELOPMENT OF THE OZONIZER AND OZONATION TECHNOLOGY FOR WATERWORKS IN JAPAN

Advanced water treatment facilities are used widely, mainly to remove taste and odor and to reduce trihalomethane generation. Each such facility consists of an ozonation and biological activated carbon (BAC) process and has made the achievement in wateworks (Sato, 2002). To make these facilities more efficient, a large number of researchers were taken to make the ozonizer more efficient and to enhance treatment technology. The ozonizer was reduced in the discharge gap using oxygen, and thus increasing ozone concentrations to 300 g/Nm3. However, to avoid incomplete combustion and ensure safety, ozone concentrations must be within 150 g/Nm3 (Ishioka, 2002; Mizutani et al.,1999). The present report also demonstrates that ozonation technology is effective in removing taste and odor and in reducing trihalomethane ( Morioka et al., 1993; Morioka, 2001); and that bromate information can be suppressed by keeping concentrations of dissolved ozone to no more than 0.1 mg/L ( Kato et al 2002). To spread and establish ozonation more widely, basic research with demonstrative plants must be conducted with regard to ozonation techniques that are capable of handling raw water from waterworks.