The ZQXN peripheral transmission full bridge suction dredger is used in circular secondary sedimentation tanks of sewage treatment plants. It scrapes and collects the sludge settled at the bottom of the tank to a set of suction pipe openings arranged along the radius direction, and then discharges it through the central discharge pipe for sludge reflux or concentration dewatering. At the same time, the floating slag on the tank surface is directed to the slag collection hopper and discharged outside the tank through the slag collection hopper for further treatment