Sedimentation tank

The utility model relates to the technical field of sewage treatment, in particular to a sedimentation tank. A sedimentation tank comprises: a housing provided with a side plate, a bottom plate and an opening allowing sewage to enter, the side plate extending out of the housing to form a mounting plate, and the bottom plate being provided with a drain outlet; the sewage discharging structure is arranged on the outer side of the bottom plate and comprises a first gear, a conveying barrel and a screw rod, the conveying barrel and the sewage discharging opening are correspondingly arranged, and the first gear is fixedly connected with the extending end of the screw rod; the power structure comprises a telescopic piece arranged on the mounting plate, a power piece fixedly connected with one end of the telescopic piece, and a second gear fixedly connected with the output end of the power piece and matched with the first gear, the second gear and the first gear are arranged separately, and the second gear is driven