GPS-X Technical Reference

301 Others Models
The sludge pretreatment model is available in MANTIS2LIB. Three main transformations are
described in the model.
1. Inactivation of bacterial biomass
The sludge pre-treatment normally results in bacterial inactivation. The bacterial
inactivation may happen due to disintegration of the cell wall and release of soluble
organic products. The biological inactivation will results in production of soluble and
particulate organic products. Depending on the nature of treatment as part of the COD
may be lost due to oxidation.
2. Conversion of Inert Organics (Xi and Xu)
The inert particulate COD is reduced during the sludge pre-treatment. A part of the
particulate inert COD is assumed to convert to the slowly biodegradable COD. The
particulate inert COD also solubilize and results in soluble biodegradable and soluble
inert COD. Depending on the treatment a part of the inert organic COD may be lost.
3. Conversion of slowly biodegradable COD (Xs)
The particulate slowly and very slowly biodegradable COD is solubilized and results in
the soluble biodegradable substrate.
The implemented model is an input-output model in which all the input states are
instantaneously converted to the output states. It is assumed that the retention time in the
chemical-mechanical disintegration reactors are small.
IN-LINE CHEMICAL DOSAGE OBJECT
The In-line Chemical Dosage object (Figure 11-2) can be used to simulate chemical addition for
soluble phosphorus removal and coagulation/flocculation of soluble and colloidal components.
Two chemical precipitation models chemeq and metaladd are available in GPS-X. The
metaladd model is available in all the libraries having soluble phosphorus as a state variable. The
chemeq model is not available in MANTIS2LIB. The metaladd model considers the effect of pH
and solubility product in the metal precipitation reactions.
Figure 11-2 - In-line Chemical Dosage Object
GPS-X Technical Reference