GPS-X Technical Reference

Other Models 300
EQUALIZATION TANK
In the nonreactive noreact model, the effect of dilution on wastewater components is described,
but all reaction rates are set to zero (no biological reactions are occurring). The tank has aeration
terms (for modelling of pre-aeration) and a built-in pump, and both aeration and pumped flow can
be controlled with feedback controllers (P, PI, PID) analogous to the ones found in aeration tanks
and settler/clarifier objects.
This model can be used to simulate an equalization tank either off-line or in-line, as the volume is
variable. In an off-line or variable volume mode (flow equalization), the pump connection should
be used with the proper controller set up, while for concentration equalization in fixed volume
tanks the overflow connection is best used.
Reactions can be added by double-selecting the model (noreact) and editing the rate equations of
the individual components.
SLUDGE PRE-TREATMENT
In a sludge pretreatment process, the particulate organic compounds are converted into soluble
organic compounds. The degree of solubilization normally depends on the intensity of the
treatment. There are many different types of sludge pre-treatment processes. These processes can
mainly be divided into thermal, mechanical and chemical treatment. Thermal, mechanical
disintegration, ultrasound, microwave, alkaline treatment ozonation, Fenton etc. are some of the
treatment which have been normally applied. For thermal and mechanical treatments, the main
operational parameter affecting the degree of solubilization is the specific energy input, while for
chemical treatment it is the specific chemical dose. The specific energy input and specific
chemical dose are normally expressed in terms of per unit of solids. As the mechanisms in sludge
pretreatment processes are normally too complex to describe through a mechanistic model,
empirical approach of modelling is normally adopted. For general engineering purpose, this
approach is sufficient to evaluate different options and help in decision making.
The general sludge pre-treatment process model in GPS-X includes the following
transformations.
1. The model describes the relationship between degree of solubilization to the operational
parameters like specific energy input or specific chemical dose using a solubilization
saturation curve.
2. The model allows conversion of the non-biodegradable organics into biodegradable
organics.
3. The model allows for loss of during the treatment
GPS-X Technical Reference