GPS-X Technical Reference

Attached Growth Models 230
Physical
These menu items are found under the Parameters sub-menu item Physical and contain
both real physical dimensions to describe the actual rotating biological contactor
modelled, as well as model dimensions which allow the user to specify how the physical
system will be modelled. There are two items under the heading Speed, which allow the
user to optimize the simulation speed of this model by changing the frequency of
integration for the soluble components. As seen in Figure 7-10, the real dimensions of
the rotating biological contactor require inputs such as the rbc liquid volume, the rbc
media volume and the specific surface area of media. Together, these three parameters
provide an estimation of the total biofilm surface area in the model. The submerged
fraction of the biofilm refers to the percent of the RBC submerged at any given time, the
maximum attached liquid film thickness refers to the liquid film which is considered to
be associated with the biofilm due to friction (no-slip layer), and the maximum biofilm
thickness will be reached only with infinite sloughing. The density of biofilm and dry
material content of biofilm are used to convert the concentration of each state variable
to a volume measurement. The model dimensions include the number of RBC tanks in
series or stages. The model assumes each tank or stage is of equal size. If the stages are
of unequal size (different media density and/or parallel feeding), the user should tie
individual RBC objects together to simulate the process.
Figure 7-10 - Physical Dimensions of the RBC
GPS-X Technical Reference