122
BioFlo/CelliGen 115
y
M1369-0050
User’s Guide
2
2
0
0
A
A
P
P
P
P
E
E
N
N
D
D
I
I
X
X
B
B
:
:
O
O
T
T
R
R
20.1
Determining an Oxygen Transfer Rate
The oxygen transfer rate (OTR) of all NBS fermentors is determined by a standard
sulfite oxidation test.
The standard operating conditions for determining OTR are:
Temperature: 30
°
C
Agitation: 1000
RPM
Aeration: 1
VVM
20.1.1 OTR
Calculations
OTR can be estimated by titrating a fixed amount of sodium sulfite, Na
2
SO
3
,
with air, CU+2:
2SO
3
+ 0
2
→
2SO
4
The Procedure
Calibrate the DO electrode:
•
Set zero on DO.
Fully oxygenate the fermentor with agitation and airflow.
•
Set span to 100%.
Introduce a known amount of Na
2
SO
3
into the fermentor when fully
oxygenated.
•
OTR = 30,000 n mM O
2
/L/hr
V
Δ
T
n
= number of moles of sodium sulfite
V
= vessel volume in liters
Δ
T
= time taken from DO curve at two points of 50% DO min.
