Clarifier
Scraper mechanisms for circular primary and secondary clarifiers, with bridge and drive arrangements matched to tank size.
Clarifier mechanisms for sewage, water and effluent treatment
A clarifier separates suspended solids from water by gravity. The water is slowed down in a large tank so that solids settle to the floor, where a scraper mechanism collects them, while the clear water leaves over the weir at the top.
Adroit builds clarifier mechanisms for primary and secondary clarifiers in sewage treatment plants, water treatment plants and industrial ETPs. Each is designed around the tank diameter, depth, hydraulic load and sludge characteristics of the project.

Primary and secondary clarifiers
Application
In a sewage treatment plant, the primary clarifier removes settleable solids from screened, degritted sewage before biological treatment, reducing the load on the aeration system. The secondary clarifier follows the biological process and separates the activated sludge from the treated water; part of that sludge is returned to the aeration tank and the rest is wasted to the sludge line.
Where chemical coagulation is needed, a clariflocculator is used instead, because it adds a flocculation zone in the centre of the tank.
How a clarifier works
Operation
Water enters at the centre through a feed well that spreads the flow and slows it down. As it moves slowly outwards, solids settle to the floor. Clear water flows over the peripheral weir into the launder.
The bridge rotates slowly, driven from the centre or at the periphery. Scraper blades attached to it sweep the settled sludge along the sloping floor to the central sludge hopper, from where it is withdrawn. A surface skimmer can be added to push floating scum into a scum box.
Where clarifiers are used
Application areas
Primary clarification in STPs
Removes settleable solids before biological treatment.
Secondary clarification in STPs
Separates activated sludge from treated effluent.
Water treatment plants
Settling of raw water solids where flocculation is not required.
Industrial effluent treatment
Solid–liquid separation in ETPs and CETPs.
Why choose Adroit's clarifier mechanism
Features & advantages
Designed for your process
Mechanism designed around surface loading, solids load and sludge characteristics.
Continuous sludge collection
Scrapers move settled sludge to the hopper as the bridge turns.
Drive to suit tank size
Central or peripheral drive; full or half bridge.
High-torque drive with overload protection
Protects the mechanism if sludge builds up.
Scum removal option
Surface skimmer and scum box where required.
Clarifier specifications
Dimensions & manufacturing
Primary / secondary
Clarifier duty
Full bridge / half bridge
Bridge type
Central or peripheral
Drive
Mild steel (painted) / SS 304 / SS 316
Material of construction
Flow, surface loading rate, solids load, sludge characteristics, tank geometry
Design inputs
Frequently asked questions
FAQ
What is a clarifier used for?
It separates suspended solids from water or wastewater by gravity settling and removes the settled sludge from the tank.
What is the difference between primary and secondary clarifiers?
Primary clarifiers remove settleable solids before biological treatment. Secondary clarifiers separate biological sludge from treated water after the biological process.
How is a clarifier different from a clariflocculator?
A clariflocculator has a flocculation zone in the centre for chemically treated water. A clarifier provides settling only.
How is sludge removed?
Scraper blades on the rotating bridge move settled sludge to a central hopper, from where it is pumped or drained out.
What do you need to design a clarifier mechanism?
Design flow, tank diameter and depth, surface loading rate, solids load and sludge type.
Brochures, datasheets & media
Downloads
Documents
files
Photos
photos
Videos
videos
Explore more solutions
Related technologies
Chain Flight Sludge Scraper
Continuous sludge and scum collection for rectangular settling tanks, driven slowly and steadily by heavy-duty chains.
Grit Mechanism (Detritor)
Square detritor with rotating scraper and reciprocating rake classifier that settles, collects and washes grit before it can wear out pumps and fill up tanks.
Clariflocculator
Flocculation and clarification in one circular tank, designed to CPHEEO guidelines, in full bridge, half bridge, central and peripheral drive versions up to 60 m diameter.
Need fine screening sized for your inlet works?
Send us your flow rate, channel dimensions and the fine-solids you need to capture — our engineers will recommend the right Stepflow configuration.
Call us
+91 70248-48383Email
[email protected]
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