The Final Clarification Step
In the mechanical clarification step, the particulate matter caused by the biological process is separated out as excess sludge via sedimentation.
For this process two technical conditions must be fulfilled: the sludge has to be heavier than the surrounding water and second, turbulences in the clarifier tank must be avoided. The excess sludge sinks to the tank bottom due to its higher density and is withdrawn from the tank bottom in certain intervals for storage in the sludge tank. For this withdrawal it is important that the sludge remains not too long in the clarifier tank, as otherwise it will float due to anaerobe digesting and gas formation. This floating sludge can be removed under normal conditions, although rather difficultly.
In the field of final clarification, System S&P® has worked with the lamella separators for decades. These separators are specially adapted to the technology of the rotating immersion discs. The higher density and resulting higher sinking velocity of the fixed film excess sludge are helpful in this process. The construction concept of very short settling distances leads to an extremely compact construction. System S&P® lamella separators require only about 20% of the surface of conventional clarifiers. This allows the settled sludge to be thickened up to 1,5%-vol of dry matter.
System S&P® lamella separators are also used as intermediate clarifiers and in a wide range of technical sedimentation processes for industrial applications.