GPS-X Technical Reference

Digestion Models 276
Composite Variables
snhn
snhi
slfn
slfi
pH
hco3
= free ammonia (moles/L)
= ionized ammonium (moles/L)
= non-ionized volatile fatty acids (moles/L)
= ionized volatile fatty acids (moles/L)
= pH
= bicarbonate (moles/L)
h2co3 = carbonic acid (moles/L)
co2
Mathematical Model
= carbonate (moles/L)
salk = alkalinity (g/m 3 )
The mathematical equations used in the liquid and gaseous phases are provided in the
corresponding Model matrix form in Appendix A. The general reaction pathway is shown
in Figure 10-2.
Stoichiometry
Figure 10-2- General Reaction Pathway
The relative amounts of chemical components produced by the biological and chemical
reactions in the anaerobic digester are specified by stoichiometric coefficients. The
chemical reaction stoichiometry is defined by the balanced chemical reaction equations.
The biological stoichiometry is defined by the yield coefficients.
GPS-X Technical Reference