GPS-X Technical Reference

Influent Models 68
WASTEWATER INFLUENT MODELS
The influent models available in GPS-X depend on the model library and the local biological
model used to relate the state variables to the composite variables. The manner in which the state
variables are calculated sometimes differs from model to model and library to library. This
chapter discusses the models available and the flow choices available with the batch influent
object.
Figure 5-6 - The Influent Models
(Panel A - Wastewater, Panel B - Chemical Dosage)
Each influent model calculates a complete set of library-dependent state variables that are passed
to the rest of the plant layout. The influent models differ only in the type of information required
as inputs to the model.
The descriptions of the influent models that follow are an overview of how they work; however,
due to their complexity and their dependence on the local biological model, and the library
currently in use, users are referred to the Influent Advisor to understand the calculations being
made in each model.
BODbased
The BODbased influent model is the choice when BOD data is available and COD data is
not available; however, due to the approximations and the nature of the BOD
measurement, special care must be taken to properly estimate influent particulate inerts.
If this model is selected, the user inputs total carbonaceous BOD 5, 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 (Figure 5-7
and Figure 5-8 and several stoichiometric fractions).
GPS-X Technical Reference