Bioprocess Engineering of Phototrophic Marine Organisms 9.2 Growth Characteristics of Phototrophic Suspension Cultures 265
Part B | 9.2
a) Concentration of species (mmol L
–1 )
b) Concentration of species (% of total)
0
1
2
3
4
5
pH
Total
Bicarbonate
Carbonate
15 °C
35 ppt seawater
350 ppm CO 2 in air
[CO 2 ] = 0.014 mmol L
–1
6.0
6.5
7.0
7.5
8.0
8.5
9.0
0
20
40
60
80
100
pH
Carbon dioxide
Bicarbonate
Carbonate
6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0
Fig. 9.3a,b Calculated speciation of dissolved carbon dioxide to carbonate and bicarbonate ions as a function of pH
in a seawater-based liquid medium using air as the aeration medium. Conditions: 15
ı C, 35 ppt seawater, CO 2 partial
pressure of 0:00035 atm (350 ppm CO 2 at 1 atm total pressure), Henry’s law constant for CO 2 of 0:026 L atm mmol
1 ,
equilibrium dissolved CO 2 concentration of 0:014 mM. (a) Molar concentrations of bicarbonate .HCO
3 / and carbonate
(CO
2
3 ) versus pH; (b) molar percentage of dissolved CO 2 , bicarbonate, and carbonate versus pH
Table 9.3 Equilibrium properties for the speciation of CO 2 in fresh water and seawater. All values are obtained from Raven [9.21]
Equilibrium property
Variable name
T ( o C) Value
Units
fresh water 35 ppt seawater
Dissolved CO 2 concentration in equilibrium with
35 Pa gas phase CO 2
(CO 2 ) or C A
5.0
15.0
25.0
35.0
22.43
15.95
11.90
9.27
18.75
13.46
10.18
8.06
mol L 1
Henry’s law constant for CO 2
H(CO 2 )
5.0
0.0154
0.0184
L atm mmol
1
15.0
0.0217
0.0257
25.0
0.0290
0.0339
35.0
0.0373
0.0428
Dissolved O 2 concentration in equilibrium with
20:95 kPa gas phase O 2
(O 2 )
5.0
15.0
25.0
391.5
298.3
236.0
310.8
240.8
mol L 1
Henry’s law constant for O 2
H(O 2 )
5.0
0.5280
0.6651
L atm mmol 1
15.0
0.6930
0.8584
25.0
0.8759
1.0683
Dissociation constant for bicarbonate (HCO 3
)
pK a;1
5.0
6.52
6.11
15.0
6.42
6.05
25.0
6.35
6.00
35.0
6.31
5.97
Dissociation constant for carbonate (CO 3
2 )
pK a;2
5.0
10.55
9.34
15.0
10.43
9.23
25.0
10.33
9.10
35.0
10.25
8.95
Part B | 9.2
a) Concentration of species (mmol L
–1 )
b) Concentration of species (% of total)
0
1
2
3
4
5
pH
Total
Bicarbonate
Carbonate
15 °C
35 ppt seawater
350 ppm CO 2 in air
[CO 2 ] = 0.014 mmol L
–1
6.0
6.5
7.0
7.5
8.0
8.5
9.0
0
20
40
60
80
100
pH
Carbon dioxide
Bicarbonate
Carbonate
6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0
Fig. 9.3a,b Calculated speciation of dissolved carbon dioxide to carbonate and bicarbonate ions as a function of pH
in a seawater-based liquid medium using air as the aeration medium. Conditions: 15
ı C, 35 ppt seawater, CO 2 partial
pressure of 0:00035 atm (350 ppm CO 2 at 1 atm total pressure), Henry’s law constant for CO 2 of 0:026 L atm mmol
1 ,
equilibrium dissolved CO 2 concentration of 0:014 mM. (a) Molar concentrations of bicarbonate .HCO
3 / and carbonate
(CO
2
3 ) versus pH; (b) molar percentage of dissolved CO 2 , bicarbonate, and carbonate versus pH
Table 9.3 Equilibrium properties for the speciation of CO 2 in fresh water and seawater. All values are obtained from Raven [9.21]
Equilibrium property
Variable name
T ( o C) Value
Units
fresh water 35 ppt seawater
Dissolved CO 2 concentration in equilibrium with
35 Pa gas phase CO 2
(CO 2 ) or C A
5.0
15.0
25.0
35.0
22.43
15.95
11.90
9.27
18.75
13.46
10.18
8.06
mol L 1
Henry’s law constant for CO 2
H(CO 2 )
5.0
0.0154
0.0184
L atm mmol
1
15.0
0.0217
0.0257
25.0
0.0290
0.0339
35.0
0.0373
0.0428
Dissolved O 2 concentration in equilibrium with
20:95 kPa gas phase O 2
(O 2 )
5.0
15.0
25.0
391.5
298.3
236.0
310.8
240.8
mol L 1
Henry’s law constant for O 2
H(O 2 )
5.0
0.5280
0.6651
L atm mmol 1
15.0
0.6930
0.8584
25.0
0.8759
1.0683
Dissociation constant for bicarbonate (HCO 3
)
pK a;1
5.0
6.52
6.11
15.0
6.42
6.05
25.0
6.35
6.00
35.0
6.31
5.97
Dissociation constant for carbonate (CO 3
2 )
pK a;2
5.0
10.55
9.34
15.0
10.43
9.23
25.0
10.33
9.10
35.0
10.25
8.95