Paper Mill Sludge Dewatering Decanter Centrifuge High Solids Screw Press

The LW520 paper mill sludge dewatering decanter centrifuge is built for the demanding environment of pulp and paper wastewater treatment. Paper production generates primary sludge rich in fibers and fillers together with secondary biological sludge from activated sludge basins. Both streams are notoriously difficult to dewater because of their gelatinous structure, fine particle size and high bound water content. This horizontal decanter tackles the problem with a 520 mm diameter bowl rotating at up to 2600 rpm, creating a centrifugal field that compacts the sludge into a dense cake while the clarified water overflows through the adjustable weir plates. A heavy duty screw conveyor inside the bowl, protected by welded tungsten carbide wear tiles, moves the compacted solids forward and out of the machine without clogging.

Operating cost is a decisive factor in paper mills, where sludge handling can represent a significant share of the wastewater budget. The LW520 therefore features an energy optimized drive train with a high efficiency main motor and a frequency controlled back drive that recovers energy during braking. Polymer consumption is minimized by an integrated flocculation system with static mixer and aging tank, ensuring complete dispersion of the polyelectrolyte before the sludge enters the bowl. Typical results reach above 25 percent dry solids from mixed primary and secondary sludge without lime conditioning, and the machine is able to run continuously for weeks between scheduled maintenance stops.

• High solids output: achieves 25-30 percent dry solids on mixed paper mill sludge, reducing disposal volume and hauling cost.
• Tungsten carbide wear protection: conveyor flights and solids discharge ports are hard faced to survive abrasive fiber and filler loads.
• Energy efficient drive: IE3 main motor combined with regenerative back drive lowers specific energy consumption per ton of sludge.
• Integrated polymer dosing: matched flocculation unit with aging tank and dosing pumps ensures stable floc formation and low chemical cost.
• Heavy duty bearings: oversized SKF bearings with oil bath lubrication tolerate high solids torque and provide long maintenance intervals.
• Corrosion resistant shell: stainless steel guards and paint system protect the machine inside humid paper mill buildings.

Typical installations include integrated pulp and paper mills, recycled paper plants, cardboard and containerboard factories, tissue mills and deinking plants. The decanter dewaters primary clarifier sludge, waste activated sludge and mixed sludge before mechanical drying, incineration or land application. It is also used for fiber recovery from white water and for thickening of sludge upstream of membrane bioreactor systems, helping mills meet strict discharge limits while recovering valuable fiber for reuse.

The LW520 is assembled in our ISO 9001 certified workshop and subjected to a full load test with representative sludge before packing. Rotating parts are dynamically balanced to G2.5 and all pressure parts are verified by hydro test. Export packaging consists of a reinforced plywood crate or open top container with the machine bolted on a steel skid, protected by vapor phase inhibitor film. We deliver a complete engineering package including PID diagram, electrical schematic, installation manual and spare parts list, and our after sales team offers on site commissioning, operator training and remote diagnostics during the warranty period of 12 months.