The central drive sludge scraper is a sedimentation tank sludge discharge equipment manufactured by our company, primarily used in municipal and industrial wastewater treatment projects for circular or square radial flow sedimentation tanks.
Powered by a drive unit mounted on the central platform or working bridge of the tank, this equipment drives the cantilevered scraper arm to rotate slowly around the central shaft, collecting settled sludge at the bottom into the central collection hopper for continuous sludge discharge. Featuring a compact structure, short transmission path, and stable operation, it serves as a widely adopted sludge scraping solution for small and medium-sized sedimentation tanks (particularly those with diameters or side lengths between 6 and 30 meters).
- Structure and Working Principle
- Core structural composition
The device features a vertical center-driven structure, primarily comprising the following components:
- The driving device, which is usually composed of vertical motor, cycloidal pinwheel reducer or gear reducer and overload protection device, is the power core of the equipment.
- Vertical shaft of central drive: A high-strength steel main shaft transmits torque from the drive unit to the underwater scraper arm system. The shaft is typically equipped with underwater bearings as auxiliary support to ensure smooth operation.
- Scraping arm and scraper system:
- Scraper arm: generally two or more symmetrical steel cantilever beams rigidly connected to the central vertical axis.
- The sludge scraper plate, installed at the base of the scraper arm, is fabricated from stainless steel or polymer materials. Its angled design facilitates the centralization of sludge from the pool's periphery.
- Work platform/bridge: Provides operational space for equipment installation and maintenance, typically installed above the tank.
- Power collection unit (for powered models): Located in the central rotating section, it facilitates power and signal transmission between the rotating equipment and the fixed power source.
- Safety and control system: featuring torque protection, audiovisual alarms, and an electrical control cabinet, supporting both automatic and manual operation modes.
- Working Principle
After the device is started, the drive mechanism drives the central vertical shaft and the scraper arm system to make low-speed continuous circular motion around the central axis of the tank.
The settled sludge at the pool bottom is continuously propelled by rotating scrapers, gradually sliding along the inclined slope (typically designed to tilt toward the center) toward the central sludge collection hopper. Subsequently, the sludge is discharged from the pool through the sludge discharge pipe under hydrostatic pressure or subsequent pumping equipment. The separated supernatant then flows uniformly out through the peripheral overflow weir.
- Compact structure and rational layout: The power system is centrally arranged at the center of the pool, eliminating the need for complex peripheral transmission components. This simplifies the overall structure and helps save space.
- The transmission path is direct and the efficiency is high: the power is transferred from the center to the scraper arm directly, the transmission chain is short, the mechanical efficiency is good, and the energy consumption is relatively low.
- Stable operation and easy control: The central drive mechanism ensures fixed trajectory and simplified control. The integrated torque protection device automatically triggers alarms or halts operation in case of abnormal load surge, safeguarding equipment integrity.
- Installation and maintenance are relatively easy: the main mechanical and electrical components are located on the central platform or on the water, which facilitates routine inspection, lubrication and maintenance operations.
- Extensive adaptability: By adjusting the length and structural form of the scraper arm, it can be adapted to sedimentation tanks of various diameters or side lengths, and can also be designed as either full-bridge or semi-bridge configurations according to the tank type.
- Main technical parameters
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Parameter item
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Description / Typical range
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Applicable pool diameter/length
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Circular pools: Diameter from Ø6m to Ø30m; Square pools: Side length can be designed accordingly
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The water is deep by the pool.
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According to the process design, the common length is 3.0m to 5.0m.
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driving power
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Based on the calculation of pond diameter, water depth, and sludge load, the common range is 0.37kW to 1.5 kW.
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scraper rotation speed
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Approximately 1-3 revolutions per hour (linear speed of about 1.5-3 m/min), adjustable as needed
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Center vertical axis material
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Typically high-quality carbon steel (with heavy-duty anti-corrosion surface) or stainless steel
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Grass scraper material
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Stainless steel (304), reinforced nylon, or ultra-high molecular weight polyethylene (UHMW-PE)
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control method
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Standard control cabinet (manual/automatic), with optional PLC interface for remote monitoring
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- Typical Application Fields
The central drive sludge scraper is designed for round or square sedimentation tanks requiring continuous automated sludge discharge.
- Municipal sewage treatment: primary sedimentation tank and secondary sedimentation tank in urban sewage treatment plant.
- Industrial wastewater treatment: sedimentation tanks in wastewater treatment plants for industries such as papermaking, food, chemical, and pharmaceutical.
- Water treatment: Sludge discharge from the reaction sedimentation tank in the water treatment plant.
- Other solid-liquid separation scenarios, such as sludge thickening tanks.
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