| 摘要 |
PROBLEM TO BE SOLVED: To improve the capacity and stability of the flocculating and concentrating device at the time of flocculating fine particles without using any flocculant, to miniaturize the device, to transfer the giantic floc formed in a flocculation tank to a solid-liq. separation chamber without releasing the small particles, to grow the flocs into a concd. sludge and to obtain a closed system without generating excess sludge by setting this flocculating downcomer in the existing solid-liq. separation chamber in an activated-sludge process. SOLUTION: A double hose consisting of a mixing pipe (outer pipe) and an injection pipe (inner pipe) is used, the discharge port of the injection pipe is opened in the mixing pipe, the double hose is spiraled, the discharge port 8 of the mixing pipe is opened in a volume increasing pipe, the discharge port 31 of the volume increasing pipe is opened in a flocculation tank 7, the residence time in the tank is controlled to several min to form the floc having 50 mm diameter, the flocs are transferred to a solid-liq. separation chamber 10 through a spiral downcomer 23 as the flocs easy to concentrate, and a sludge at >=13 kg/m3 is obtained from the bulking sludge.
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