Before working with complex technology or using chemicals, specific heavier ingredients need to be separated from the aqueous phase by sedimentation or gravity separation. These processes are simple, do not need any additional facilities worth mentioning and have proved reliable for years.

proaqua offers different systems:

• Round tanks with funnelled bottoms (Dortmund tank principle)
• Inclined plate clarifiers (counterflow systems preferred)
• Centrifugal separators / centrifuges / decanters

Round tanks with funnelled bottoms
The principle is simple: The settling rate of the solid matter has to be greater than the water's rate of ascent . The parameters are established on a laboratory scale and then included in the dimensioning with the appropriate safety factor. There is a central supply from above via a guiding and settling pipe. The settleable solids have to reliably slide down the funnel wall to the lowest point, while the clarified water phase flows over a surrounding skimming edge at the top.

Typical fields of application are:
sludge thickening following neutralisation/flocculation/precipitation; separation of biomass in biological sewage treatment plants; useful for flow outputs of approx. 5 m³/h upwards.
The advantage of this system is its simplicity. Consequently, it is easy to manage, easy to access depending on which design is concerned and good value.

However, the relatively long sedimentation periods mean that larger dimensions are needed in comparison to other solutions. In all cases, further sludge drainage with a decanter or filter press is to be recommended.


Inclined plate clarifiers
To reduce the settlement distance - and therefore the retention time - inclined plates are positioned in a container. In the case of counterflow inclined clarifiers, the flow travels upwards over these plates from below; the sludge settles on the upper side of the plates and then slips downwards. Efficiency increases as the angle decreases until it is horizontal; however, the sliding action suffers as a result. This is why preliminary testing is also to be strongly recommended in this case.

Typical fields of application are:
sludge thickening following neutralisation/flocculation/precipitation; separation of biomass in biological sewage treatment plants; useful for flow outputs of approx. 1 m³/h upwards.
A relatively low dry solid matter content occurs in the dilute sludge as a result of the short retention time; this means that secondary thickening may be necessary.
Further sludge drainage with a decanter or filter press is recommended.
The advantage of this system is that comparatively-speaking it has a considerably lower capacity and requires less space.


Centrifugal separators / centrifuges / decanters
In centrifugal or cyclone separators the medium is accelerated by introducing it tangentially, so that heavier particles build up in the outer zone and are then transported downwards. The clarified water is discharged centrally.

Typical fields of application:
the separation of specific, clearly heavier particles up to approx. 50 µm; e.g. in the purification of cooling lubricants and grinding water, etc.
This system is only partly suitable for abrasive substances; in addition, pressure needs to be increased by using a feed pump, for example.
In many cases, its extremely good value, space-saving design makes the cyclone separator an attractive piece of technology.


The medium is mechanically accelerated in centrifuges (many times the force of gravity "g"). The force of gravity is determined by the drum diameter and speed. Decanters are relatively slow running centrifuges; the solids are removed from the centrifuge's drum with a screw conveyor. Decanters achieve solid contents of up to approx. 30%.

Typical fields of application are, for example, sludge drainage from flotation systems, following thickeners and inclined clarifiers.
Although this system requires a relatively high amount of power, the advantages have to be mentioned - excellent separation performance even with the smallest of particles, as well as possible 3-phase separation.

Your contact person will be pleased to advise you in detail.