COP™ Spiral Blade Clarifier

COP Spiral Blade Clarifier for Rapid Solids Removal

The WesTech COP™ Spiral Blade Clarifier is the result of our research and design focus on building a better clarifier. Each COP Spiral Blade Clarifier is designed for the specific process requirements of each plant. Proprietary algorithms result in a clarifier that provides high performance.

Clarifier Reference Kit


For more than 30 years, with more than 1,500 installations, WesTech has been improving the performance of both primary and secondary clarifiers with our Clarifier Optimization Package (COP).

Read more about 30 years of spiral blade clarifiers

WesTech COP clarifiers:

  • Optimize the clarification process
  • Produce the cleanest possible effluent
  • Maximize underflow concentration

The influent center column of the COP clarifier is sized and ported to both prevent settling and systematically reduce incoming velocities. WesTech’s unique Dual-Gate™ EDI nearly eliminates hydraulic energy as the flow enters the feedwell. Flow enters at the water surface, ensuring that the full volume of the flocculation well is used for gentle mixing and flocculation of the biological solids. Opposing gates are arranged so that incoming flow impinges on itself, effectively dissipating incoming energy and eliminating focused flow streams that could carry into the clarification zone. The result is a well-flocculated mixed liquor that spreads gently and evenly into the clarifier without disturbing settled solids on the basin floor.

Dual-Gate EDI

Side-by-side studies show a 27 percent reduction in effluent suspended solids using the new Dual-Gate EDI versus a conventional EDI in shallow secondary clarifiers. WesTech’s Dual-Gate EDI is just one of many benefits provided by the COP.

This highly efficient clarifier design uses multiple key design parameters to optimize the physical forces and limitations occurring in any clarifier to achieve superior performance:

  1. Scum Removal: Removes scum build-up from within the feedwell and from the clarifier surface. Includes a scum flushing valve that automatically opens to flush scum out of the scum trough.
  2. Density Current Baffle: Eliminates wall currents and prevents short-circuiting. The wall-mounted baffle is low in cost and requires no maintenance.
  3. Flocculating Feedwell: Promotes hydraulic flocculation in the inlet area and is designed to eliminate scouring of the sludge blanket.
  4. Energy Dissipating Inlet (EDI): Converts the high energy feed from the center column into a lower velocity flow that is gently mixed in an impinged flow into the flocculating feedwell to maximize flocculation.
  5. Spiral Rake Blades: Increase sludge transport capacity, providing rapid solids removal, and lower sludge blankets. Eliminate septicity and denitrification.
  6. Premium Drive Unit: Designed for torque requirements from 1,000 ft-lbs to 6,000,000 ft-lbs, the Premium Drive Unit provides rotational force to the clarifier mechanism while resisting torque loads and overturning moments.
  7. Center Column: Minimizes floc shearing and reduces influent energy.
  8. Sludge Withdrawal Ring: Reduces the depth of the sludge blanket in a secondary clarifier – decreasing sludge scour and increasing hydraulic capacity, as well as reducing the possibility of denitrification and phosphorus removal in BNR processes. The Sludge Withdrawal Ring provides rapid solids removal in conjunction with Spiral Rake Blades, while eliminating the need for underwater seals.
  9. Basin Configuration: Uses deeper side water depth (SWD) and proper floor slope design for maximum capacity and highest effluent quality for the least cost.
  10. Effluent Launder Covers: Eliminate algae growth and minimize maintenance time.

Benefits and Features

  • Moves sludge inventory from the outer portions of the tank to the center
  • Simplicity of design
  • Wide range of operational applications
  • Reduces denitrification flotation
  • No clogging problems often associated with other rapid sludge removal clarifiers
  • Performance is not affected by location of settled sludge
  • Reduces rat-holing
  • Results in lower solids over the weir and lower torques
  • Results in greater solids thickening
  • Increased sludge transportation

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