Settled sludge from the sludge thickening tank is crushed by a sludge cutter and then transported by a sludge feed pump. After being metered by an electromagnetic flowmeter, it is combined with the prepared flocculant solution fed into the flocculant dosing system and fed into a centrifugal dewatering machine. After separation in the dewatering machine, the sludge becomes a solid/liquid two-phase system. The liquid phase (clarified liquid or separated liquid) is directly discharged or returned to the sedimentation tank, while the solid phase (dewatered sludge) is discharged by a screw conveyor to a transport vehicle for off-site transport.
In the automatic flocculant dosing system, powdered flocculant is added from the hopper (material feeder) and then into the preparation tank by an automatic powder feeding device (colloidal flocculant is added directly to the preparation tank by a metering pump). At the same time, tap water enters the preparation tank through a flow meter and is automatically prepared into a solution of a certain concentration (approximately 0.08–0.15%). The prepared solution flows into the storage tank and is transported by a dosing screw pump. After being metered by an electromagnetic flow meter, it is mixed with sludge from the sludge thickening tank through a manifold (or static mixer). The centrifugal force generated by the high-speed rotation of the centrifuge causes the denser material (solid phase) in the suspension entering the drum to settle and separate under the action of centrifugal force and centrifugal liquid pressure, and then enter the dewatering machine for sludge dewatering.
