GPS-X Technical Reference

253 Sedimentation and Flotation Models
CHAPTER 8
Sedimentation and Flotation Models
This chapter provides a description of the sedimentation and flotation models available in GPS-X.
SEDIMENTATION MODELS
Sedimentation is one of the most important unit processes in activated sludge treatment plants.
The sedimentation unit, whether it is a primary settler, secondary clarifier, or sludge thickener,
provides two functions: clarification and thickening. The primary settlers and sludge thickeners
are designed and operated to take advantage of the thickening process, while the secondary
clarifiers are designed and operated to take advantage of the clarification process.
In GPS-X, the sedimentation models are either zero- (point) or one-dimensional (1d suffix), and
either reactive (mantis, asm1...) or nonreactive (simple). The following models are available:
Zero-dimensional, nonreactive: point
One-dimensional, nonreactive: simple1d
One-dimensional, reactive: mantis, asm1, asm2d, asm3, newgeneral
In reactive models, biological reactions are included, and the model names are associated with the
corresponding suspended-growth models, described in Chapter 6 (page 94). For example, the
mantis sedimentation model uses the mantis suspended-growth model.
One-Dimensional Models
In the one-dimensional models, the settler is divided into a number of layers (10 by
default) of equal thickness, as depicted in Figure 8-1.
The following assumptions are made:
1. Incoming solids are distributed instantaneously and uniformly across the entire
cross-sectional area of the feed layer.
2. Only vertical flow is considered.
GPS-X Technical Reference