CARRIER FLOWING OUT PREVENTION MECHANISM FOR WATER TREATMENT DEVICE

PROBLEM TO BE SOLVED: To provide a catchment mechanism for a moving bed type aerobic filtration bed capable of collecting good treated water by inhibiting flowing out of a solid substance to the treated water without inhibiting a flow of a carrier at the time of washing. SOLUTION: Raw water is flowed from an upper part of an aerobic filtration bed tank 10 filled with a carrier and a fine solid substance in the raw water is captured by the carrier during that it descends in the filtration bed tank. After the contaminant dissolved in water is decomposed by microorganisms deposited on a surface of the carrier, the treated water flows out from a catchment area 12 at a lower part of the filtration bed tank to the outside of the tank. Whereas, after the carrier on which the solid substance is deposited by a biological treatment and which descends is raised by an air lift pipe 29 provided at a center of the filtration bed tank 10, the carrier from which the solid substance is separated is circulated into the filtration bed tank. In the filtration bed tank 10, a carrier flowing out prevention mechanism is disposed, which comprises a diffusion umbrella provided on an outer periphery of a protection pipe 25 of the air lift pipe for diffusing the carrier descending into the catchment area 12; a catchment cylinder 30 extending from a small diameter side of the diffusion umbrella to a height arriving at a half part of a central water collecting part 11 at the filtration bed tank; and a treated water flowing out pipe 14 projected from an upper outer wall of the water-collection cylinder to the outside of the tank. COPYRIGHT: (C)2003,JPO