GPS-X Technical Reference

Suspended Growth Models 166
A helpful warning alarm can be set in the Membrane Backwash …More… menu. The
“warn if tank is overflowing or empty” alarm will print information to the Command
Window if the filter flow causes the final tank to overflow or become empty.
A membrane flux controller can be activated to maintain the trans-membrane pressure at
the membrane flux setpoint using a built-in controller with the rate of pressure
increase being the controller gain.
The cross-flow air used to clean the membranes is assumed to be delivered using a
coarse-bubble aeration system. The alpha factor for cross-flow air is based on total
suspended solids concentrations of between 8,000 mg/L and 10,000 mg/L in the MBR.
The standard oxygen transfer efficiency (cross-flow) is based on a coarse bubble aeration
system at submergence of 4.3 m (14 ft.).
The cleaning frequency sets how often physical/chemical cleaning is used to reset the
membrane fouling resistance to zero.
Display Variables
Several membrane-specific display variables are available to be plotted. The Membrane
Filter Variables menu is accessed from the overflow connection point (not the filter
connection point), and is shown in Figure 6-15.
The MBR Cake Variables menu (shown in Figure 6-16) provides display variables for
total cake mass and cake thickness.
Tips on Using the MBR Models
The following points are useful to keep in mind when setting up an MBR simulation:
Use Simple Mode initially to establish the required operating conditions, such as
MLSS, SRT, waste flow, etc.; and in cases where details on the maintenance of
the permeate flux are not required. If you are only interested in the biological
treatment aspects of the system, use Simple Mode. If you need to also simulate
the physical aspects of the filter operation (i.e. different backwash cycles, TMP
management, etc.), then Advanced Mode is required.
When using Advanced Mode, pay close attention to the volume in the reactor(s),
as it is easy to either drain or overfill the reactor that contains the membrane
filter.
GPS-X Technical Reference