Suction Header Clarifiers

Larger units or high MLSS may require dual headers.

220 Ft Dia. Suction Header

Suction Header Design

Header design starts with dividing the tank into annular rings then sizing the suction header holes to withdrawn the amount of sludge within that ring.

Hole size and ring width is adjusted to achieve a balanced withdrawal rate across the clarifier bottom

One or two round or square tapered headers stretch from a manifold radially across the bottom of the clarifier.  Varying size and spaced orifices located in the leading edge of the suction header are designed to draw settled sludge at an even removal rate across the entire basin floor.  Through pumping, or head differential, settled solids are drawn through the header into the manifold and out of the clarifier.  

ADVANTAGES:

1.  Rapid removal of solids across the whole clarifier floor.

DISADVANTAGES:

1.  Potential plugging of the suction header holes at low RAS removal rates.
2. If the actual RAS flow rate is different than designed for, the header may
   draw solids at an uneven rate across the basin floor.
3. Because the header draws equal to the area it rotates through, a sludge
          blanket must be maintained over the entire clarifier deeper than the
          suction header.
4. A seal must be maintained between the rotating manifold, the clarifier
          center column, and the tank floor.  High head differentials for the
          suction header may cause the seals to collapse or “suck in” rendering
          them useless.  
5. The seals must be replaced approximately every 5 – 7 years.

VARIATIONS:

1.  Install a segmented rake as one arm opposite the suction header to aid
   in redistribution of the sludge on the bottom.