Suction Pipe Clarifiers

Suction or Riser Pipe design works by lowering the water level in the RAS box causing a head differential between the water level in the tank and the RAS box causing settled solids are drawn up from the tank floor into the RAS box. An adjustable orifice in the RAS valve allows the amount of settled solids to be optimized from the different locations of the clarifier bottom.  

Adjustable Orifice in the RAS Valve

Suction or draw-off pipes are equally spaced along the rake arm to draw off settled sludge across the clarifier.  Blades on the rake arm are arranged in a “V” pattern to direct the collected sludge towards the Suction Pipe.  A RAS valve, located in the RAS Box, on each individual suction pipe allows the flow from each pipe to be adjusted to optimize the solids removal from the clarifier leading to potential higher RAS concentrations.

ADVANTAGES:

1. Rapid removal of settled solids across the entire basin floor.
2. Optimization of the flow removal across the clarifier bottom as process conditions change.
   
   

DISADVANTAGES:

1. Potential plugging of the suction pipes and, in particular, the valves.
2. A seal must be maintained between the rotating RAS box the clarifier center column.
3. Highest capital cost of all clarifier designs.
4. The required RAS valve box makes adding an Influent Dispersion Well (IDW) or an Energy Dissipation Well (EDI) difficult.
5. Many times the Suction Header Clarifier is not utilized to its full potential due to the higher sophistication of operation.