Screw Flow Centrifugal – RAS, Low Head, Digested Sludge- Wemco

Wemco Screw Flow Pump from Trillium Flow Technologies is ideal for return activated sludge (RAS) service where the pump could perform against a low total dynamic head while operating close to its best efficiency point (BEP) where bearing loads and shaft deflections are at a minimum. The screw-shaped impeller has improved clog-resistance was also required to eliminate maintenance to free the pumps from rags. The screw centrifugal pumps feature a single, spiral vane impeller with no blade edges exposed to the flow. A cutting groove cast into the liner shears off material that builds up around the impeller periphery and re-introduces it into the flow. The steep head-capacity curve produced by the impeller provides additional head to help push through any partial blockages.

Screw Flow Pump

  • Suitable for municipal sludge (up to 5% solids)
    • Adds energy to get thickened sludge moving
  • Operates at High efficiencies (up to 80+%)
  • Low Shear Pump to keep from damaging the biological floc
  • Gentle pumping action
  • Low NPSH requirements compared to other centrifugal pumps.
  • Hard metal components available for abrasion resistance: Ni-Hard and High Chrome Iron
  • Suction Liner – externally adjustable that allows convenient adjustment of internal clearances to compensate for wear.
  • Back pull-out power frame for ease of maintenance

Common Applications

  • Ideal for RAS & WAS applications (low head) where it operates near BEP even at heads of 7 to 20 ft
  • Digester mixing
  • Sludge storage tank mixing
  • Transfer pump (Digester)
  • Raw Influent Pumps and Lift Stations
  • Lime Sludge
  • Centrifuge Feed

WEMCO Prerotation Basin

Simple and Economical: The WEMCO® Pre-rotation Basin was designed to direct flow to the tangential entrance channel. The direction of flow through the channel creates a rotation of the fluid inside the prerotation basin, before it enters the pump. The rotation of the fluid inside the basin folds floatable solids off the surface and into the pump flow stream, allowing removal from the wet well. The rotation also breaks up surface vortices, allowing a much lower minimum operating level than with conventional submersible pump stations. This lower operating level scours the bottom of the wet well, re-suspending settled solids so they too, can be removed from the wet well. The combination of removing the floating and suspended solids results in a wet well that automatically cleans itself every time the prerotation pump runs through its operating cycle.

• Eliminates expensive vacuum truck cleaning and labor costs
• Reduces odor, gas and corrosion
• Floatables are folded into the suction of the pump
• Settled solids are carried to the pump
• Lower overall energy use than variable speed installations
• Less capital investment than other systems
• Less maintenance than traditional wet well installations
• Straightforward controls
• No manual, labor intensive, and time consuming wet-well wash-down
• Easy retrofit to existing stations
• Built-in shelf supports and anchors the base elbow of the submersible pump, properly aligning the pump to the basin
• Lightweight fiberglass basins are filled with concrete during on-site construction, eliminating expensive transportation costs

Product Assistance

Please describe the products or service needs in the short form below and our technical assistants will work closely with you to ensure you have all necessary parts shipped instantly. You can also call our experts at 800-366-7867.

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