Centrifuge Technology

Veolia Separations prepares the sludge stream for the Centrifuge by screening it, mixing it, and chemically conditioning it as necessary. Typically, the centrifuge will require a polymer to flocculate the solid particles and perhaps a de-emulsifier to break emulsified oil/water/solid streams (commonly called “rag”). The sludge is injected with the polymer (and de-emulsifier if necessary) “in-line” then passed through a static mixer to flocculate the solid particles (and “water wet” the solids by the action of the de-emulsification agent).

Oily waste streams often benefit from heating (up to 180 degrees F) to decrease viscosity and enhance the ultimate oil/water/solid separation. The conditioned sludge is pumped to and through the centrifuge using positive displacement feed pumps so as not to shear the “floc” formed by the polymer injection process.

Veolia owns and operates a fleet of skid-mounted centrifuges in a wide range of sizes, “G-force” ratings, and flow capacities. The centrifuges have a wide range of adjustments (pool depth, differential speed, rpm, etc.) in order to “dial the machine into” the specific sludge stream.

The flocculated “feed” sludge is pumped into the feed port of the centrifuge where it is subjected to high centrifugal forces (in excess of 2500 G’s). The high “G” force takes advantage of the difference in specific gravity and thus separates the solids from the liquids. The solids collect and dry out on the elongated “beech” area of the bowl until they are augured to the solids discharge port. The liquids collect close to the interior of the unit (in effect “on top” of the solids) and are discharged from the liquid port.

Dry centrifuge cake (solid phase) and clear centrate (liquid phase) can be achieved on almost any type of sludge by expert operation of quality equipment.

Advantages of Centrifuge Technology

• Continuous feed process typically requiring less labor/operator effort
• Best technology for most oil/water/solid and latex sludge streams

Disadvantages of Centrifuge technology

• Typically requires polymer/chemical addition to pre-condition sludge
• Centrifuge cake is not as “dry” as filter press cake, therefore, less waste volume reduction
• Operation requires higher skill level and more experience
• Operation requires greater amount of electric power compared to filter press and belt press technology