GPS-X Technical Reference

215 Suspended Growth Models
The PAC model calculates the amount of “fresh” PAC (PAC that is available to sorb
components), and “used” PAC (PAC that has components sorbed onto it, and is not
available to sorb more), and the fraction of total PAC that is “fresh” and available to sorb.
The model calculates the concentrations of individual components that are bound to PAC.
For PAC-bound soluble substrate, the biomass will grow at an enhanced rate, due to the
presence of a concentrated substrate source. This enhancement of growth is controlled by
the bioregeneration factor, by which all of the biological growth rates (that grow on ss)
are multiplied. The consumption of PAC-bound ss frees up the “used” PAC to become
“fresh” PAC again.
TOXIC INHIBITION IN IP LIBRARIES
In the CNIP and CNPIP libraries, the above-described functionality is enhanced by the addition
of user-defined toxic components and their sorption properties. Users can use the IP library
versions of the PAC object to investigate the relationship between toxic inhibition and PAC
addition to sorb the toxics.
Toxic Inhibition
The growth rates for biomass (both heterotrophic and autotrophic) in the Mantis
biological model is appended with a switching function for the presence of toxic
inhibitors. The user must identify which components are the toxic components, and
specify the relative inhibition of each component. The Toxic Inhibition menu contains
the parameters used in the inhibition switching function. Figure 6-30 shows the Toxic
Inhibition menu, with sza (IP state variable “soluble component ‘a’”) filled in as Toxic
Component #1.
Figure 6-30 – Toxic Inhibition Menu
GPS-X Technical Reference