SBR tanks

Hello!

I have been trying to run a simulation with an SBR tank, but the results indicate that no sludge is being created (the Q_Under is zero). Has anyone else encountered the same problem?

Q_Under is non-zero only in period T5 when it is set equal to the parameter Q_Waste (if the tank is not empty)

Yes, but it's not normal every component in the underflow to be zero, right?

Certainly not. But the main (only) thing you need to look at is the flow rate: is QUnder = 0 all the time? If so, you need to figure out why.
A couple of suggestions: look at the periods (if they are controlled and T5 happens to be zero ...); at the volume (is there sufficient volume to allow for extraction?). Also: I assume you are looking at a plot of QUnder. Is the communication interval sufficiently small to capture the expected change of QUnder during T5? The integrator and its settings may also contribute to conceal the change in QUnder.