GPS-X Technical Reference

Suspended Growth Models 190
The pH that is determined for each reactor can be set to inhibit biological growth, using the pH
inhibition settings in the Physical parameters more… button. The pH inhibition is set to OFF
by default.
The growth of biomass is multiplied by a pH inhibition factor, taken from
Grady and Lim (1980), which is bounded between zero and one. This creates a linear decline
between pH = 7.2 and pH ≈ 6.1.
Equation 6.56
Open Basic HPO (MANTIS2LIB library only)
The open basin HPO unit process models the gas-liquid transfer processes for a pure
oxygen fed activated sludge process. The open basin systems are considered to provide
good oxygen transfer efficiency while allowing better exchange of CO2. The better
exchange of CO2 prevents excessive drop in pH. The open basin HPO model has the
following features:
1. A gas-liquid transfer model based on feed gas and outlet gas composition
2. Temperature estimation model based on energy balance
3. High temperature and kinetic parameter relationship
Typical outputs from the energy balance model and the oxygen transfer model are shown
in Figure 6-27 and Figure 6-28.
GPS-X Technical Reference