bezinkingssettlementtanks

Bezinkingssettlementtanks, or sedimentation tanks, are large circular or rectangular basins used in water and wastewater treatment to remove suspended solids by gravity. They are typically located after coagulation and flocculation steps in water treatment, or after primary treatment in wastewater plants, and provide a period of quiescent flow that allows particles to settle.

Principle and design: Inlet zones distribute water evenly; flow travels slowly across the tank to minimize turbulence. Settled solids accumulate as sludge at the bottom, removed by mechanical scrapers or sludge pumps, and often directed to sludge handling facilities. Clarified water exits over adjustable weirs or troughs at the top. Many tanks include features such as baffles to reduce short-circuiting, hopper bottoms for sludge collection, and optional inclined-plate settlers or tube settlers to increase effective settling area.

Performance and operation: Detention time depends on treatment goals and loading, typically ranging from minutes to several hours. Efficiency depends on uniform flow, proper chemical dosing, and maintenance to prevent scum buildup or sludge blanket formation. Regular sludge removal is essential to maintain capacity and performance.

Applications: Used in municipal wastewater treatment as primary clarifiers, in secondary clarifiers for biological treatment, and in drinking-water plants as primary sedimentation to remove turbidity and solids before filtration.

Maintenance and safety: Regular inspection, cleaning, and monitoring of flow distribution, weirs, and downcomers are required to prevent short-circuiting and overflow.