The invention discloses a single-
tube suction dredge, comprising a dredging tube which is arranged at the bottom of a
sedimentation tank and is movably connected and communicated at the inside and outside thereof by a sealing cylinder in a sealing manner, a traction arranged, a bridging device which is arranged in the
sedimentation tank and tows the dredging tube and the sealing cylinder, and a driving device. The bridging device comprises a central column, a central
rotating disc, a working bridge, a central vertical frame and a pulling rod of the dredging tube which are fixed in the
sedimentation tank; the central
rotating disc is movably coupled with the central column to form a revolving support and is coupled with the working bridge and the central vertical frame outside of the central column. A skimming device is coupled below the working bridge; one end of the working bridge is coupled with the central column by the central
rotating disc movably and the other end thereof is coupled with the driving device and travels along the edge of the tank; the working bridge is fixedly connected with the dredging tube by the pulling rod of the dredging tube; and the central vertical frame is fixed coupled with the working bridge and the sealing cylinder. As the periphery is adopted to drive the dredging tube, the single-
tube suction dredge has simplified structure, less disturbance to muddy water, good skimming effect, light weight for a main
machine and low cost, and is particularly applicable to the primary sedimentation tank with larger
sewage sludge concentration and the large sedimentation tank of more than 50m.