PURPOSE: To prevent the oxidation consumption of bioactive carbon in later stages in the water treatment method using ozone and the bioactive carbon by injecting a ferrous ion-contg. soln. into a soln. contg. the dissolved ozone after an ozone treatment to reduce the dissolved ozone.
CONSTITUTION: Raw water is formed with flocs by addition of a flocculating agent thereto and is subjected to a flocculation setting treatment in a flocculating treatment tank 5 in the water treatment method using the ozone and the bioactive carbon. This flocculation treated water is sent into an ozone reaction tank 6 where the water is subjected to an ozone reaction. The partly unreacted ozone dissolves in the treated water and flows out as the dissolved ozone to a connecting piping 11 at this time. The ferrous ion-contg. soln. is taken from a injecting liquid storage tank 14 and is injected into the ozone treated water by an injection controller 16. The dissolved ozone and dissolved oxygen are then reduced in this order and the concn. thereof is decreased. This concn. is measured by a dissolved oxygen meter 15 and the injection rate of the soln. is controlled by the injection controller 16. The ozone-treated water is treated in an ozone bioactive carbon column 9. As a result, the oxidation consumption of the active carbon is prevented by the decrease of the dissolved ozone.
TANAKA KOJI
TAKEMURA MINORU
UMIGA NOBUYOSHI
