Air Dissolution in an Air Saturator of a Dissolved Air Flotation (DAF) System

Question

Good day guys
Currently, I am working on air dissolution in an air saturator of a DAF system.  We all know that increasing recycle ratio and saturator pressure are two options to increase the mass concentration of the air. This is mentioned in existing literature of DAF systems.
However, as we increase the recycle ratio, we decrease the hydraulic retention time in saturation tank which finally leads to a less air dissolution. This is against what literature said. I am a bit confused!!

Vincenzo Scarlata · Answer

Dear Vahid,
All dissolution air reactors are sized in function of hydraulic retention time so when you exceed the maximum input flow the results will worsen. (If your car is sized for 4 people but you have 6 people to transport is better to change car)
The reactor geometry, the mixing intensity and the air diffusion system inside the reactor can change the HRT required.
To have an high flotation efficiency  is also essential to have an high quality air bubbles.

Rafael Gay-de-Montella MSc PEng · Answer

I like to add to Ademar comment: Dissolution of air is fast and depends mostly in the physical means to do it (geometrical),
HRT (Hydr. Ret. Time) is not of importance unless too small in comparison to the kinetics of air dissolution. In practice HRT is only there to allow for feed water flow fluctuations.

AGGASIT DAD · Answer

Sometime we look for 1 or 2 topics but DAF desing on calculation of flow and FOG including Pressure. And working on site we will khow the performance of them. And do not forget about chemical as well. I think the operater need skill of monitering ....observing..and find out the maximum or the high efficiencey point.

AGGASIT DAD · Answer

Sometime we look for 1 or 2 topics but DAF desing on calculation of flow and FOG including Pressure. And working on site we will khow the performance of them. And do not forget about chemical as well. I think the operater need skill of monitering ....observing..and find out the maximum or the high efficiencey point.

Ademar Cesar Ferreira · Answer

In the air flotation system another important factor is saturation tank efficiency of mixing air and water as expansion valve that is used. They are both very important and can help to reduce retention time in saturation tank. There are manufacturers that use a pipe to mix air and water. Regards.

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