sedimentationstanke

Sedimentationstanke, or sedimentation tanks, are gravity settling vessels used to remove suspended solids from liquids in water treatment and wastewater systems. They rely on the natural settling of particles: heavier solids deposit as sludge at the bottom, while lighter materials may rise to the surface as scum to be skimmed off. The clarified liquid exits over weirs after passing through the tank.

In operation, the influent flow is distributed to minimize turbulence and to promote uniform settling. Inlet structures and baffles help distribute flow and reduce short-circuiting. Sludge is collected at the bottom by scrapers or moving bottoms and is pumped away for thickening or digestion. Surface scum is removed with skimmers or troughs. The main controls are detention time (hydraulic retention time) and ballast management to maintain a stable sludge blanket and prevent resuspension of settled solids.

Sedimentation tanks come in several configurations. Circular tanks (clarifiers) and rectangular basins are common, with variations such as covered or uncovered designs. They may be used as primary clarifiers in municipal wastewater treatment, where they reduce the load on biological treatment stages, or as secondary clarifiers after biological processes like activated sludge. In drinking water treatment, sedimentation basins (often called clarification basins) remove a substantial portion of the suspended solids following coagulation and flocculation.

Key design and operational factors include tank geometry, surface loading rate, detention time, temperature, and sludge management. Maintenance focuses on keeping baffles clean, ensuring effective sludge and scum removal, and preventing excessive sludge buildup or gas accumulation.

Sedimentation tanks are fundamental components in many water and wastewater treatment plants, balancing simplicity and effectiveness to achieve initial or final solids removal before downstream treatment.