Ozone used for this system as an Active Substance has strong oxidizing property and is effective for disinfecting aquatic organisms. Its half-life period in the water (seawater, for instance) is as short as 5.8 seconds and Ozone remains there for a very short term. Therefore, no Ozone remains in the ballast water when discharged. In the seawater, by the reaction of Ozone and bromide ion, bromate is generated. Bromate ion also has a strong oxidizing property and contributes to disinfecting. The half-life period of bromate ion is on an average 12 hours which is longer than that of Ozone and impact on the environment by discharged ballast is a matter of concern.

　

 Active Substance and relevant chemical used in this application is as shown in Table 3.

　

　

　

 Ozone as an Active Substance is produced by a generator provided on board. Since this process is not a commercial preparation using additives, etc., it is not described in this application form.

　

　

 In this application form, Ozone is defined as an Active Substance. Ozone exists in oxygen (raw material) at a ratio of 6 to 12%. Therefore, when it is used for treating the ballast water, it is in a state of Ozone gas. Components of Ozone gas are shown in Table 4.

　

　

　

 In this application form, bromate ion generated during treatment of the ballast water of the seawater is defined as a relevant chemical.

　

 Products generated by the reaction between Ozone and bromate ion in the seawater are hypobromous acid ion, hypobromous acid and bromate ion. Ratio of their existence varies under the influence of pH. Among these products, only the bromate ion as generated in the presumable pH range of 5 to 8 in the ballast water. Generally bromide ion accounts for 60 mg/L in the seawater but 0.1 mg/L or below in the fresh water of rivers, etc. Therefore, the volume of bromate ion generated when Ozone of 4 mg/L (the maximum feeding ratio in this system) is added, makes a substantial difference between the seawater and fresh water. The volume of bromate ion (measured as value of oxidant) when Ozone of 4 mg/L is added into the seawater is about 1.6 mg/L in 2 days (see section 8, Toxicity testing of the treated ballast water). In a short navigation, however, this concentration of the ballast water discharged may be potentially higher under the influence of the water quality or water temperature. For this reason, bromate ion was defined as a relevant chemical in the seawater. In the fresh waters, on the other hand, the volume generated is on the level of ppb and the influence on the environment may be actually ignored and bromate ion is not defined as a relevant chemical.

　

　

 Physical and chemical properties of Ozone and bromate ion and ballast water after being treated with this system are shown in Table 5.

　

　

　

　

　

 There exist regulations on Ozone concentration for the water of the swimming pools in Germany, the European Union, Italy, etc. In the case of Germany, DIN Specification regulates the residual Ozone concentration as lower than 0.5mg/L and also the corresponding residual chlorine concentration as a different value.

　

　

 In Japan, Ozone is regulated as a constituent of oxidant or photochemical oxidant. Standard value (value permitted in an hour) under the Basic Environment Law and the Air Pollution Control Act is 0.06ppm and O.l2ppm respectively. United States environmental standards are shown in Table 6^6),7),8).

　

　

　

 WHO determined the recommended value on bromate ion in the Drinking-water Quality Guidelines in 1993. The tentative value of the Guidelines was 25μg/1.^10),11)

　

 In the 1998 revision of the universal drinking water standard in the European Union, the standard bromic acid values were determined to be 25μg/1 by 2OO3 and 1Oμg/1 by 2OO8.

　

　

 Ozone is used as a disinfector for the city water, hygiene materials, breaching agent of agricultural chemicals at the stage of manufacture, compound intermediate of chemical compound raw materials, etc.