GPS-X Technical Reference

251 Attached-Growth Models
Figure 7-20 - Upflow and Downflow Denitrification Filter Objects
Biological Component
The denitrification filter model uses the same biological reactions found in the
suspended-growth models. For more specific information on biological models, please
consult Chapter 6 (page 94).
Biofilm Component
The existing biofilm model in GPS-X is based on Spengel and Dzombak (1992). This
model was adapted for use in the attached-growth objects such as the trickling filter and
denitrification filters. The model handles soluble material diffusion, biofilm growth, and
particulate attachment and detachment. Details are described in the Trickling Filter
Model section of this chapter.
Filtration Component
The filtration of solids is modeled as a simple capture of the particulate state variables
from the effluent layer of the denitrification filter (bottom layer in the downflow filter
and top layer in the upflow filter). Users specify a capture fraction, and all solids
captured are removed through the backwash connection stream. Backwashing (and its
associated removal of solids) is modeled as a continuous process flow.
Model Parameters
Physical
This section of the chapter discusses the various model parameters and inputs that the
user will encounter when using this model.
The physical parameters are found under the Parameters sub-menu item Physical. It
contains physical dimensions to describe the denitrification filter, and model dimensions
which allow the user to specify how the physical system will be modelled.
The denitrification filter requires inputs such as the specific surface of media and the
porosity of media.
GPS-X Technical Reference