Splitter Box design

[SchuylkT]

I am designing a splitter box at the head of an SBR WWTP. The box will split the flow into either three or four paths. I intend to have the influent line dump into a small equalization basin, which will then feed to 3 or 4 lines equally as the water rises. The problem, though, is that the influent water has too much energy and is likely to rush violently to the farside of the equalization tank, rather than settle and rise. I've considered placing a baffle prior to the equalization tank. Does anyone have any other ideas?

 

[mmo]

Schuylkt:
I believe that you should put some baffling on this eq tank, but if the total volume of the tank is too small compared with the actual flow i.e has a low retention time it will be difficult to dissipate all the energy of the incoming fluid.
try with a income thru a inverted elbow quite near the bottomm and directed to it.
rgds
mmo

 

[BobPE]

mmo is right, you are going to have to convert velocity head to pressure head in order for the hydraulic gradients out of the splitter box to be equal in the various effluent pipes. Don't fall into the trap of thinking its a small plant and the splitter box wont make that much difference if I wing it. The smaller designs are always where the problem seems to be int he field. A good splitter box design should work without valving so strive for that and put valving in to balance the flow when you are done.

BobPE

 

[SchuylkT]

Thanks for the feedback. Based on your responses, I am considering feeding the influent thru the bottom of the tank and placing a baffle somewhere between in influent pipe and the effluent pipes. But this design raises new questions regarding variations in flow conditions? I am concerned that during low flow, the influent flow may not rise high enough into the splitter box. And during peak flow, the flow might be a "gusher". Also, any concerns about clogging or "caking" in the elbow. (The splitter box will be preceeding by screens only)

FYI: current flow = 1 MGD, future flow (after expansion) = 5.5 MGD

 

[BobPE]

Assuming the splitter box is fed by a pumped gradient, I would think you would get enough head during low flows and not enough during high flows. You have to design it to take this into account in addition to planning for that expansion.

Solids deposition will be a concern if you dont design it with the correct velocities. You concentration should be on the elbow exit velocities and keeping them low. Baffles will have to be designed that same way if you choose to use them.

BobPE