anoxic zone baffle wall

[vodeni]

I am designing a baffle wall inside a concrete aeration tank. The baffle is to create a separate anoxic zone for the denitrification. Any suggestions regarding the material, construction and type of flow (over or under the wall)would be appreciated. Thank you

 

[rcooper]

When I have done this previously I have used concrete with openings at the base which could be isolated with penstocks. It did mean the concrete wall has to be designed to withstand the anoxic zone being full when the aeration lane was empty.

I have also looked a grp panels supported on stainless steel. This cost less, but required a lot of bracing off the walls to be stable. If you went with this underflow is realy the only option and isolation is not possible.

 

[PatColeman]

You have to decide whether they are predominatly over or under baffles. The baffle into the aerated part of the tank should be an "over". In this case design to have 80% to 90% of the flow go over the top and the balance through a slot in the bottom. This means the baffle does not have to be water retaining. Allow an extra 10mm in the drop to take account that aerated water is less dense than unaerated. You must prevent dissolved oxygen being transported into the anoxic zone or you may get low DO bulking. This is why you allow the extra 10mm.