GPS-X Technical Reference

317 Others Models
DISC AND BELT MICROSCREENS
The disc and belt microscreen objects also contain the empiric solids separation model, as
described above, but with different default removal rates. The disc microscreen object is found in
the “Tertiary Treatment” object group, and the belt microscreen object is found in the
“Preliminary Treatment” object group. Both objects have only the empiric solids separation
model.
HIGH-RATE MODEL (HIGHRATE)
Figure 11-11 – Belt and Disc Microscreen Objects
The High-Rate unit process object is found in the “Biosolids Treatment” section of the
unit process table. It contains the highrate solids separation model.
Highrate Model Background
The highrate model is based on a vortex separator and retention treatment basin (RTB)
model developed by Gall et al. (1997) and Schraa et al. (2004) for the high-rate treatment
of wet weather flows such as combined sewer overflows (CSOs). The model has been
applied to primary clarifiers, chemically enhanced primary clarifiers, RTBs, vortex
separators, continuous backwash filters, and ballasted flocculation (e.g. Actiflo) and
sludge recycle (e.g. Densadeg) systems.
The highrate model contains a hydraulic routing component and a settleability
component. The hydraulic component of the model consists of algorithms to achieve
dynamic volumetric and mass balances. The settleability component of the model
includes a relationship between settleability and influent TSS concentration, and a
relationship between settleability and the surface overflow rate (SOR). The settleability
model for high-rate retention treatment basins is given below:
GPS-X Technical Reference