GPS-X Technical Reference

185 Suspended Growth Models
Set recirculation velocity – specify a constant surface velocity of CFSR flow
Set constant recirculation flowrate – rather thatn specifying velocity, set the
flow
Set proportional recirculation flowrate – make the CFSR flow proportional to
the incoming flow to the CFSR.
Set constant outlet fraction – specify the fraction of the flow that exits the
CFSR each time around.
Set proportional to bridge – set the recirculation rate proportional to the
rotational period of the aeration bridge (simulate rotaing aeration brigde does not
have to be on for this option to function)
Please Note: Due to the high recycle rate within the object (and subsequent short HRTs
for each section of the reactor), the CSR model often will take longer or fail to converge
to steady-state with the steady-state solver. You may find it necessary to increase the
iteration termination criteria in the steady-state solver menu to achieve a reasonable
solution.
If you are having difficulty with steady-state solutions, you can halt the steady-state
solver at a higher iteration termination value, and run a short dynamic simulation to test if
the steady-state solver solution is adequate. If the dynamic solution does not diverge
appreciably from the steady-state conditions, then the higher iteration termination value is
suitable. If you have any questions or problems, please contact us for assistance at
support@hydromantis.com.
Rotating Aeration Bridge
The CFSR consists of a circular tank with an aeration grid suspended from a rotating
bridge, though stationary aeration grids can be installed on the floor along the perimeter
of the tank. When modelling the rotating aeration bridge, airflow specified in the total
airflow to rotating diffusers is moved around the tank from one CSTR cell to the next
over the specified rotational period. The rotational period of aeration bridge specifies the
period of time required for the rotating diffusers to make one revolution around the tank.
GPS-X Technical Reference