GPS-X Technical Reference

Attached Growth Models 236
The next two items in this form under the heading Speed, concern the integration of the
soluble components. Since these components are diffusing through the biofilm, and
consequently change rapidly when compared to the particulate components, which are
changing only due to their growth rates, they dominate the numerical solver. To increase
the speed of simulation, it was found that these components could be integrated less
frequently without loss of accuracy. When the soluble variables are scheduled to be
integrated their derivatives are calculated as normal. Otherwise, the derivatives are set to
zero. There are two variables which are used to specify how frequently the states are
integrated (Soluble integration period) and the duration for integration or how long the
states are integrated for each period (Soluble integration length). These concepts are
shown in Figure 7-3, with the results for ammonia shown in Figure 7-4.
The oxygen mass transfer coefficient is calculated from the physical conditions within the
filter (thickness of biofilm and diffusion rate of oxygen) and is affected by temperature
and the saturated dissolved oxygen concentration. These values are input in the general
data entry area or specifically set for each object as shown in Figure 7-13.
Figure 7-13 - Physical Dimensions of the SBC (More...)
GPS-X Technical Reference