GPS-X Technical Reference

73 Influent Models
TSSCOD
Figure 5-10 - CN Library States Influent Model Influent Stoichiometry Inputs
The tsscod influent model can be used successfully if the influent was characterized
using COD and suspended solids as the main components. The tsscod influent model was
developed based on the Activated Sludge Model No. 2 report (Henze et al., 1995).
If this model is selected, the user inputs total COD, total TKN, total suspended solids, a
few state variables (the state variables are normally zero except for the soluble inert
organics, soluble ortho-phosphate (CNPLIB) and alkalinity and several stoichiometric
fractions. These inputs are then used to calculate the remaining state variables (Figure
5-7 and Figure 5-8).
Particulate COD (XCOD) is calculated from the TSS using two stoichiometric fractions.
This is then divided into its component parts via stoichiometric fractions or explicitly as
read from the data input forms leaving the particulate inert organics component (xi) to be
calculated by subtraction. Figure 5-12 shows how the soluble COD (SCOD)
components are calculated from the COD, XCOD and the stoichiometric parameter, frsi.
See the bodbased model for the calculation of the nitrogen and phosphorus (CNPLIB)
state variables. It is recommended that Influent Advisor be used to understand these
calculations.
GPS-X Technical Reference