GPS-X Technical Reference

139 Suspended Growth Models
Particulate Inorganic
The particulate inorganic states include the model precipitates like aluminum hydroxide,
aluminum phosphate, iron hydroxide, iron phosphate, calcium carbonate, calcium
phosphate, magnesium hydrogen phosphate, magnesium carbonate, and ammonium
magnesium phosphate (struvite). In addition to these precipitates, particulate inert
inorganic is used as a composite state for the unidentified inorganic in the wastewater.
The N and P components associated with the slowly biodegradable organics are included
as nitrogen in slowly deg. organics and phosphorous in slowly deg. organics. The
inorganic poly-phosphate accumulated in PAO is also included as a state.
Composite Variables
Processes
MANTIS2 uses a well-defined stoichiometry for each state variable to estimate the
composite variables. The state variables and their relationships to the composite variables
are shown in the Composite Variables in MANTIS2LIB section of Chapter 4, GPS-X
Composite Variable Calculations.
The processes included in the MANTIS2 model are described below:
Adsorption/Enmeshment
1. Adsorption of colloidal COD: The colloidal COD (scol) is considered to
first adsorb on the heterotrophic biomass. The adsorbed colloidal COD then
becomes a part of slowly biodegradable COD (xs) and requires hydrolyses
before it become available for bacterial metabolism. As both the ordinary
heterotrophic organism and fermentative organism are considered to
participate in the hydrolysis process, the rate of adsorption is defined with
respect to the sum of the concentration of two organisms. The adsorption rate
is first order to the colloidal COD. A rate inhibition term is added to reduce
the rate of adsorption as the ratio of slowly biodegradable COD to adsorbing
biomass increases.
Processes mediated by heterotrophic organisms
2. Aerobic hydrolysis: The heterotrophic microorganisms are considered to
participate in the hydrolysis of slowly biodegradable substrate X S resulting in
production of soluble fermentable substrate (ss). Surface limited hydrolysis
kinetics similar to that used in ASM1 and ASM2d is used. Both the ordinary
heterotrophic organism and fermentative organism are considered to
participate in the hydrolysis process
GPS-X Technical Reference