Bezinktanks

Bezinktanks, also called settling tanks, are a type of tank used in wastewater treatment to remove suspended solids by gravity. They are employed in both primary and secondary treatment stages in municipal and industrial plants. Water flows slowly through the tank, allowing heavier particles to settle to the bottom as sludge while clarified water exits near the top.

A bezinktank is typically circular or rectangular, constructed from concrete or steel, and may include internal baffles, a surface weir, and a sludge withdrawal system. Sludge is collected at the bottom by mechanical scrapers or pumps and is regularly removed for digestion or further handling. Some designs also include scum removal at the surface.

Operational performance is described by hydraulic retention time and surface overflow rate. Primary clarifiers target relatively coarse solids with shorter retention times, while secondary clarifiers in activated-sludge systems provide longer retention to separate biomass from treated water. The design aims to minimize short-circuiting and scum buildup, maintain even flow, and accommodate inflow variations.

Maintenance and safety considerations include regular desludging, scum removal, and inspection of mechanisms and access hatches. Cleaning of surfaces and components helps prevent fouling and ensures reliable operation. Bezinktanks play a central role in reducing the load of solids entering downstream biological processes and in providing a stable supply of clarified effluent for further treatment or discharge. See also clarifier, sedimentation basin, activated sludge process, and wastewater treatment.