| 摘要 |
PURPOSE:To increase water loading capacity per unit area of a settling basin by providing a discharing means of fiter medium and a stripping means of sludge sticking to the discharged sludge to a filtration tank, providing also a returning means of stripped sludge to an aeration tank and a returning means of the filter medium to the filtration tank to the stripping means. CONSTITUTION:A part of the sludge in the sludge mixture supplied from an aeration tank 1 to a filtration tank 3 sticks to the floatable filter medium 2 gathered densely from the middle stage upto the water surface or setlles to the bottom of the tank. The filter medium 2 is discharged successively from an overflow port 3' and the filter medium freed from the sludge is sent to the middle stage of the tank and is circulated. A discharged pipe 13 is connected to a lower half section of a filtration tank 3 and the filtrate having reduced sludge concn. is supplied to a settling tank or settling basin 14. By this constitution, sludge is naturally precipitated in the settling tank or settling basin even if fibrous bulking sludge is contained in the sludge mixture discharged from the aeration tank 1, and treated water contg. no sludge is discharged. |
