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Clari-Vac Secondary Settling Tank

For:refurbishments of the existing WWTP's, new WWTP's


The Clari-Vac secondary settling tanks are intended for rectangular tanks.


Technical Specifications

Technological Principle

The floats (1) carry the technology that employs the joined vessels principle to suck off sludge from the tank bottom. The structure on floats is pulled by stainless cord (2) from one side of the secondary settling tank to the other. The sludge suck-off system outlet is submerged under the level in the lateral channel (3) of the secondary settling tank. The pump that evacuates sludge from this channel allows reaching the level difference that ensures evacuation of sludge from the bottom of secondary settling tank. Regulation of this pump output makes the difference between the levels of secondary settling tank and lateral channel lower or higher that results in increased or decreased suction effect of the joined vessels. This pump pumps sludge into the denitrification system. At the same time, all that is needed to regulate smoothly the inner recirculation of the biological line or convey sludge into the sediment trap is opening the valve in the piping into the nitrification system.

The floats also bear the scraping equipment to remove the floating impurities from the level in secondary setting tank (4) so all the floating impurities are removed automatically during each travel back and forth in the secondary settling tank to be pumped back into the biological line or, if appropriate, into the sediment trap.

Advantage of this system is its lower demand for energy and investments. One recirculation pump ensures both internal and external recirculation, removal of excessive sludge into the sediment trap as well as the transport of floating impurities. Very low energy is also required to drive the float with pipe structure and the floating impurity removal system.

The main technological advantage of this system is the fact that the sludge in the secondary settling tank is not shifted but it is directly sucked off so that the flakes on the secondary settling tank's bottom are not damaged mechanically and this contributes to a high NL removal efficiency of the secondary settling tank. Its advantage is also an easy maintenance, all the system's moving parts are above the water level, the system floats on the level without having any contact with the structural part of the waste water treatment plant so no further losses are caused due to friction or wear.