Flocsillator® Oscillating Mixer

The Flocsillator® oscillating flocculator is a horizontal shaft, oscillating flocculator mechanism that provides efficient and maintainable means to develop settleable floc. They are installed in water treatment flowsheets to achieve flocculation after coagulants are introduced and dispersed, and are typically upstream of the sedimentation unit in traditional surface water treatment flowsheets (prior to a DAF unit or granualar media filtration) as a direct filtration application.
  • Water treatment flocculation
  • Retrofit applications
  • Staged or tapered flocculation
  • Low speed flocculation



Flocsillator Mixer Installation

  • Flocculation is accomplished using oscillating motion
  • Low flocculation tip speeds are employed
  • All bearings and the drive shaft are located above liquid level
  • Several layouts are available

When rotation occurs in a basin, particles do not move relative to one another, do not come into contact with one another and do not form settleable floc. Baffles are not very effective in breaking up rotation of the entire basin contents. The Ovivo Flocsillator® oscillating flocculator is designed to combat rotational effects, thereby ensuring maximum floc formation. Utilizing a back-and-forth motion, fluid is not allowed to rotate about the axis of the flocculator, allowing for formation of floc. Low flocculation tip speeds ensure that formed floc will not be destroyed by the shear forces generated, as with high-speed paddle passes.

Additionally, the drive shaft and bearings are located above liquid level, so bearings are not subjected to a hostile, submerged environment, resulting in a longer bearing life. When bearings do need to be maintained or replaced, access is easy and the flocculation basin does not need to be drained. Bearings can also be lubricated more effectively because there is no concern about petroleum-based lubricants coming into contact with drinking water. The drive shaft does not pass through the basin wall, so stuffing boxes and submerged drive chains or belts are no longer required, effectively eliminating maintenance headaches.  The Flocsillator® layout can be tailored to fit the space available while still providing the desired tapered flocculation.


The unique geometry of the Flocsillator® oscillating flocculator means it does not have to rely upon induced flow to influence the entire basin. The oscillating flocculator paddles move back and forth to establish mixing currents, first in one direction and then in the other. This increases the opportunities for floc particles to contact one another without the use of baffling, which is not as effective. The paddles move close to the basin wall, first on one side of the basin and then the other, leaving only a small fraction of the basin that does not have a paddle passing through it or near it. This design provides precisely the velocity gradient required in the flocculation basin, allowing for staged or tapered flocculation.

Q: Can the Flocsillator® oscillating flocculator be installed in existing basins?

A: The Flocsillator oscillating flocculator lends itself to retrofit applications. Varying basin geometries can be accommodated. The ability to span a tank with a beam to support shaft bearings means that concrete bearing support pedestals need not be poured. Since Flocsillator drive mechanisms are above liquid level, no holes need to be cut through the tank walls for stuffing boxes, which is often required with horizontal paddle designs.

Q: Can The Flocsillator oscillating flocculator be used in a staged or tapered flocculation application?

A: Staged or tapered flocculation can be achieved with oscillating flocculators in two ways. First, with the flow directed parallel to the flocsillator shaft, the number and spacing of paddles can be modified so that a high velocity gradient is achieved near the flow inlet and then reduced to its lowest value at the point where flow exits the flocculation step in the flowsheet.  Second, with the flow directed into the flocsillator basins perpendicular to the flocsillator shafts in a cross-flow configuration, multiple units can be used to achieve the tapered effect.  The unit nearest where the flow is introduced would have the most paddles in order to achieve the highest velocity gradient value, while the unit nearest where the flow exits would have the fewest paddles in order to yield a gentle flocculating effect.

Q: What materials are used for the paddles?

A: Flocsillator paddles may be constructed of several different materials.  Steel, douglas fir, PVC, FRP, and redwood have all been used as paddle materials on Flocsillator Oscillating Flocculators.  PVC offers long life, while redwood has traditionally been used in this service.

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