GPS-X Technical Reference

Sedimentation and Flotation Models 266
Physical
These menu items are found under the Parameters sub-menu item Physical. This input
form contains the actual physical dimensions of the DAF unit being modelled, including
the tank surface area, the maximum water level or height of the tank, and the location of
the feed point relative to the bottom of the tank. The fourth item on the form allows the
user to define the number of equivalent layers contained within the model. The physical
parameter form is shown in Figure 8-7.
Operational
Figure 8-7 – Physical Parameters for the DAF Unit
The operational parameters for the DAF unit are located within the Parameters submenu
item Operational. This input form contains the polymer dosage (g polymer/kg
solids) and the air-to-solids ratio (g air/g solids) for daily operation of the DAF unit. The
maximum float flow is an upper boundary limit for the amount of float that can be
removed from the DAF unit. The operational input form is shown in Figure 8-8.
Under the sub-heading other parameters, the optimal polymer dosage and optimal airto-solids
ratio are defined. These two values provide an estimate of the best expected
solids condition. The optimal values may be expressed based on past operating
experience with the actual DAF unit or may be provided through manufacturer literature.
The dry material content of the float at the optimal polymer dosage is defined as a
percentage. The dry material content of the float without polymer dosage is also defined.
The model will use the range between these two values to predict the dry material content
of the float under actual operating conditions.
GPS-X Technical Reference