PPT Slide

Assumptions in Modeling Citric Acid Production Kinetics

(1) Citric acid is produced associated with both cell growth and

cell maintenance.

(2) Both the cell growth rate and the maintenance metabolism rate

are expressed by the combination of the Monod equation for

sugar and the dissolved oxygen concentrations.

(3) The ratio [(sugar converted to citric acid)/(sugar converted to

citric acid plus sugar oxidized for energy production)] was

assumed to be the same for both the cell growth- associated

and cell maintenance-associated metabolism.

(4) In the citric acid production period, YOC was constant

independently of time.

(5) Pseudo-steady state conditions were assumed to exist within

the biofilm.

(6) The biofilm is overlapped by a liquid medium film usually

attached to the rotating disks during rotation in the gaseous

phase. The liquid film thickness was further assumed to be

constant during rotation both inside and outside of the medium

in the trough.

(7) In the liquid film, only the oxygen concentration slope was

assumed to exist. On the outer surface of the liquid film, the

oxygen was saturated.

(8) The concentration of the substrate except for oxygen was

uniform in the trough medium and the liquid film.

(9) The cellular density changed with cultivation time, but it was

constant in the direction perpendicular to the biofilm surface.