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Supernatant Decanter

The Parkson DynaCanter™ is a floating style decanter used to remove supernatant from the upper portion of the basin.  The decanter utilizes a flex joint to allow vertical articulation as water levels move between high and low water levels.  The decanter collects supernatant from below the water surface to preclude foam, scum, or other floatables.  A series of machined orifices are provided in the decanter draw tube to collect supernatant from multiple points in the basin.  A standard open / close valve is used in the discharge piping to control flow rate through the decanter.  No electromechanical components are used inside the basin making operation and maintenance convenient for the operator. 
A cast in place wall spool (or supported spool for steel tanks
or link seal designs) is located a few feet below minimum water level.  The lower mitered elbow is bolted to the spool and is used to support the lower knee brace assembly.  A wire reinforced flex hose is used to allow the decanter assembly to move up and down with changing water levels.  An upper knee brace assembly is connected to the decanter drain tube and is pinned to the lower knee brace assembly to allow only vertical movement of the assembly.  The draw tube (lower parallel pipe) houses the machined orifices and is typically located 1-2 feet below the water surface to prevent vortexing and entrainment of floating materials.  The upper parallel pipe is the foam filled float which provides buoyancy to the unit.  Decanter rests are anchored to the tank floor and are designed to support the decanter when the tank is dewatered (and during initial installation).  The supports also act as an emergency stop in the event that the decant valve remains open after the decanter reaches bottom water level (this prevents the decanter from entering the sludge blanket).
The materials of construction are outlined in the following table. Other materials of construction are also available depending on specific project requirements.