Clarifier

Influents enter into the the energy dissipating feed well which locating in the center of the clarifier. By the work of baffle plates, the velocity of the flow slows down and the liquid starts to flow downwards

A clarifier can be split into three zones: inlet zone, settling zone and outlet zone. The settling zone is where the solids, which are heavier than the liquid, will sink to the bottom of the clarifier to form sludge, and floatable solids will accumulate on the surface of the water as scum. A rake with scraper blades will rotate gently to push the sludge inwards radially to a sludge pit where the sludge will be sucked out of the clarifier for further treatment, usually dehydrated by a screw press dehydrator

A scum skimmer will push the scum outwards radially to outside periphery of the clarifier to a scum trough. A scum baffle shall be installed to stop scum going to clean water outlet. The effluent, after removing approximately 90 to 95% of the settleable solids and approximately 40% to 60% of the suspended solids, is now quite clean. It flows through V-notched weir as thin film water to effluent launder for further treatment.

Conventional Clarifier: A conventional clarifier is a gravity sedimentation tank. They are available in rectangular or circular configurations.  

Suction Clarifier: Suction type clarifier use a vacuum system to collect the sludge from the bottom of the tank. They are used for secondary and final clarification processes.