| 摘要 |
PROBLEM TO BE SOLVED: To effectively use ozone in primary and secondary treated water and to improve the quality of treated water by using a waste gaseous ozone after being used to oxidize raw water with ozone as a gas for oxidizing the water discharged from a biological treating stage with ozone. SOLUTION: The whole or a part of treated water 36 is introduced into the upper part of the ozone contact tank 15 for secondary treated water to further improve the quality of secondary treated water 35. Meanwhile, the gaseous ozone 50 injected into an ozone contact tank 14 for primary treated water is consumed when oxidizing the org. matter-contg. water, however the injected ozone 50 is not wholly consumed and partially discharged from the upper part of the contact tank 14 as a waste gas 51 contg. unreacted ozone. The waste gas 51 is injected by a blower 23 into the contact tank from its bottom. Consequently, the residual org. matter, color and malodor in the second treated water are removed, and the water is discharged as the completely treated waters 37 and 38. |
