GPS-X Technical Reference

141 Suspended Growth Models
9. Growth on fermentable substrate (ss) using NO 3 as electron acceptor: This
process of heterotrophic growth takes place in the presence of NO 3-N. The
stoichiometry of this process is developed by considering partial reduction of
NO 3-N to NO 2-N. The rate expression for the process uses an inhibition term
for oxygen and a saturation term for the NO 3-N. The growth rate is also
considered proportional to the ratio of fermentable substrate to total soluble
substrate (ss+sac+spro) available to heterotrophic biomass. The reaction rate
expression also reduces the amount of heterotrophic biomass by the fraction
of NO 3-N to total NO X nitrogen available in the system. It is assumed that
when the heterotrophic biomass is converting NO 3-N to NO 2-N, it is not
participating in the conversion of NO 2-N to N 2 gas.
10. Growth on acetate (sac) using NO 3 as electron acceptor: The process of
heterotrophic growth on acetate using NO 3-N is similar to the process #9,
except that the growth rate is proportional to the ratio of acetate
concentration to the total soluble substrate (ss+sac+spro) available to
heterotrophic biomass.
11. Growth on propionate (spro) using NO 3 as electron acceptor: The process
of heterotrophic growth on acetate using NO 3-N is similar to the process #9,
except that the growth rate is proportional to the ratio of propionate
concentration to the total soluble substrate (ss+sac+spro) available to
heterotrophic biomass.
12. Growth on fermentable substrate (ss) using NO 2 as electron acceptor: This
process of heterotrophic growth takes place in the presence of NO 2-N. The
stoichiometry of this process is developed by considering reduction of NO 2-
N to N 2. The rate expression for the process uses an inhibition term for
oxygen and a saturation term for the NO 2-N. The growth rate is also
considered proportional to the ratio of fermentable substrate to total soluble
substrate (ss+sac+spro) available to heterotrophic biomass. The reaction rate
expression also reduces the amount of heterotrophic biomass by the fraction
of NO 2-N to total NO X nitrogen available in the system. It is assumed that
when the heterotrophic biomass is converting NO 2-N to N2, it is not
participating in the conversion of NO 3-N to NO 2-N gas.
13. Growth on acetate (sac) using NO 2 as electron acceptor: The process of
heterotrophic growth on acetate using NO 2-N is similar to the process #12,
except that the growth rate is proportional to the ratio of acetate
concentration to the total soluble substrate (ss+sac+spro) available to
heterotrophic biomass.
GPS-X Technical Reference