The invention relates to the technical field of
sedimentation tanks, in particular to a
sewage treatment
sedimentation tank which comprises a tank body, a water inlet base body and a cleaning body, the water inlet base body is fixedly mounted in the center of the tank body, a water
inlet flow channel is formed in the water inlet base body, and the cleaning body is rotationally mounted below the water inlet base body; the water
inlet flow channel comprises a water inlet energy dissipation section, a horizontal flow section and an
impurity intercepting section which are sequentially communicated in the water inlet direction, the water inlet energy dissipation section is of a vertically-arranged
wave structure, the cross section of the
impurity intercepting section is in a
funnel shape, a
reagent cavity communicated with the water
inlet flow channel is formed in the side wall of the water inlet flow channel, and a movable wall is vertically and slidably installed on the side, close to the water inlet flow channel, of the
reagent cavity; a cleaning body is rotationally mounted below the water inlet base body, the cleaning body extrudes the movable arm to vertically move during rotation so as to intermittently communicate with the water inlet flow channel and the
reagent cavity for intermittent
medicine injection, and the cleaning body relatively moves to extrude and puncture
sludge while extruding the movable arm; the problem that the
water quality is influenced by
suspended matter increase caused by floating of gas filled in the
sludge in the
sedimentation tank is solved.