SEWAGE TREATMENT TANK

PURPOSE:To apply strong movement to water so that the interior of a sedimentation tank is held to as stationary a state as possible to increase sedimentation/ separation capacity and the stagnation of sludge is not generated in the bottom part of the tank. CONSTITUTION:The aeration tank 2 and sedimentation tank 3 provided in an outer tank 1 are partitioned by a partition plate 4 and allowed to communicate with each other through the gap between the lower end of the partition plate 4 and the bottom part of the outer tank 1. By this constitution, sewage is separated into supernatant water and settled sludge in the sedimentation tank 3 and the settled sludge passes through the gap 5 to be returned to the aeration tank. Herein, a plate-shaped distributing projection 9 is provided to the almost central part of the inner surface of the tank 1 opposed to the partition plate 4 of the sedimentation tank 3 so as to protrude toward the partition plate 4.