| 摘要 |
<p>PURPOSE:To prevent sludge from depositing in a tank by making the lower section of the tank a hopper cone type in a submerged filter bed type treatment tank, forming a bottom surface plane or curved surface projecting upward and providing an air diffusion pipe of surrounding shape close to the bottom surface of the tank. CONSTITUTION:A treatment tank 1 is provided with a filter bed 12 filled with filter mediums in a peripheral section of the tank 1, and an air diffusion pipe 2 to blow air or oxygen in is provided at the lower section of a space of a central section. In such a submerged filter bed type tank 1, the lower section of the tank 1 is made a hopper cone type constituted of an inclined surface 11, while a bottom surface is formed plane or into a curved surface projecting upward and a surrounding shape diffusion pipe 2 is provided close to the bottom surface of the tank 1. Preferably the surrounding shape of the diffusion pipe 2 should not be more than the size of a space of a central section of the tank 1. Further, a blowing nozzle of the diffusion pipe 2 is installed in a manner that blowing is carried out inwardly and downwardly, preferably in the direction of 60 deg. or less, or more preferably approximately 45 deg.. Sludge falling down to the bottom of the tank 1 is flowed and circulated in the tank 1 again without depositing therein by said arrangement, and transferred to a following tank together with treated water.</p> |
