GPS-X Technical Reference

129 Suspended Growth Models
It is possible to differentiate between anoxic and aerobic nitrifier decay rates.
Ammonification of SND and hydrolysis of biodegradable, particulate nitrogen (XND) are
omitted. Instead, a constant composition of all organic components has been assumed
(constant N to COD ratio).
Alkalinity limitation on the process rates is considered.
Figure 6-8 shows a schematic of the processes simulated in the asm3 model.
Figure 6-8 - ASM3 Model Processes
The Model Matrix for asm3 is found in Appendix A.
MANTIS MODEL (MANTIS)
The mantis model is identical to the IAWPRC Activated Sludge Model No. 1 (asm1), except for
the following modifications:
Two additional growth processes are introduced, to allow for growth of heterotrophic
biomass with nitrate as a nutrient.
Switching functions for nitrogen as a nutrient (and phosphorus, in applicable libraries)
and alkalinity for growth
Separate half-saturation coefficients for oxygen for aerobic and anoxic growth, to allow
for calibration of simultaneous nitrification/denitrification.
The additional growth processes account for the observed growth of organisms during conditions
of low ammonia and high nitrate. Under these conditions, the organisms can uptake nitrate as a
nutrient source.
GPS-X Technical Reference