CIRCULAR THICKER SEDIMENTATION TANK

A circular sedimentation basin for improving the settling efficiency by causing a swirling flow to be formed through first and second discharge units and a rotary inflow well, thereby maintaining a long flowing path is provided. A circular sedimentation basin comprises: a body part including a circular water tank, a rotation transmitting part erected at the center of the circular water tank, rake arms connected to both sides of the rotation transmitting part, a sludge inflow pipe inserted into the rotation transmitting part from the bottom of the sedimentation basin, and a driver installed on an uppermost portion of the rotation transmitting part; a first discharge unit(20) which is installed in a cylindrical shape and is in communication with an end of the sludge inflow pipe, and which has a baffle(21) installed at a position thereof communicating with the sludge inflow pipe, and discharge holes(22) continuously formed in a central portion thereof; a second discharge unit(30) which is installed in a cylindrical shape on an outer periphery of the first discharge unit, and which has discharge holes(31) continuously formed in a central portion thereof, and an inclined plate-shaped variable plate(32) installed in a lower portion thereof; and a rotary inflow well(40) which is installed on an outer periphery of the second discharge unit in such a conical shape that an upper part of the rotary inflow well is narrow while a lower part of the rotary inflow well is wide, and which has a spiral slit plate(41) formed on an inner peripheral surface thereof.