flow makers in oxidation ditch

[MirJev]

Hi, its me again! I have a question regarding the design of flow makers in oxidation ditch.
I have an oxi ditch, 5,5 m deep, 2300 m3 volume, with disc air diffusers and flow makers, but I am not sure how to pick the right flow maker.
I guess the easiest way is to ask the manufacturer to quote the flowmaker that fits best, but I would like to know how to pick the right one myself.
My senior colleague told me that I should assume the energy of mixing to be 10-30 W/m3 and than get the power of the flowmaker.
When I use the energy of mixing of 20 W/m3 for my oxi ditch, I get the needed power for mixing 46 kW, which is way to big.

I have attached a layout of the oxi ditch, for your reference.

P.S. The same question stands for the design of aerobic and anaerobic selectors.

I would be grateful if you could share your vast knowledge with me once again.
Thank you,
Mirko

 

[bimr]

You have not stated what you are trying to achieve in the ditch. Are you interested in EBNR?

The manufacturers of the ditches have a great deal of empirical data to support their recommendations. You would be better off talking to the manufacturers. I assume that you would want them to guarantee the treatment results.

 

[MirJev]

I am going for BNR and simultaneous aerobic sludge stabilisation, so SRT is 25 days.
I've come across some really great diagrams from one manufacturer of mixers and flowmakers, so basically I have found what I was looking for.
Found out that the data my senior colleague gave me is valid only for small sized tanks.