GPS-X Technical Reference

Suspended Growth Models 138
Soluble Gases
In addition to soluble oxygen (so), MANTIS2 includes soluble gases states for nitrogen
(sn2), methane (sch4) and hydrogen (sh2). The soluble CO 2 is estimated by the pH and
the stic concentration in the wastewater. The soluble oxygen plays an important role in
the aerobic biological systems. The other gases are more relevant in the anaerobic
digestion and fermentation processes. For each soluble gas, gas-liquid transfer equation
are used to model the dissolution/stripping of the gas in the unit processes.
The particulate states in the model are classified into four categories of Particulate Inert
Organics, Particulate Organic Substrate/Storage, Active Biomass and Particulate
Inorganic.
Particulate Inert Organics
The model includes two states of Inert Organic Particulate (xi) and Unbiodegradable
Organic Matter from cell decay (xu) in the model. The inert organic particulate is the
inert organics fraction that is contributed by the influent wastewater. Having two states
for inert organic compounds makes it easier to differentiate between the amount of inert
organics accumulated from the wastewater and the amount that is produced by cell decay
in the system.
Particulate Organic Substrate/Storage
MANTIS2 provides one particulate Organic Substrate (xs) and one organic storage
compound for intracellular PHA (xbt). These states are equivalent to the states in
ASM2D and New General Models.
Active Biomass
Several biomass states are added in MANTIS2. To model the two step nitrification
process, two autotrophic biomass Ammonia Oxidizer (xbai) and Nitrite Oxidizer (xbaa)
are considered. Methylotrophic biomass (xbmet) is included to model the biodegradation
of methanol. The fermentive biomass (xbf), Acetogen (xbpro), acetate methanogens
(xbacm) and hydrogen methanogens (xbh2m) are included to model the anaerobic
transformation in anaerobic digestion.
GPS-X Technical Reference