Kinetics and Energetics of Photosynthetic Micro-Organisms in Photobioreactors
195
Table 5. Comparison between the Spirulina mass volumetric growth rate in biomass calculated by
the proposed model and experimentally determined on continuous cultures in a cylindrical photobioreactor for different biomass concentrations and incident radiant energy fluxes (Permission fi'om
Elsevier)
Biomass
Incident radiant
Volumetric growth
Volumetric growth
Standard
Concentration
energy flux
rate in biomass
rate in biomass
deviation
Cx (kg.m-3)
FR (W.m-2)
(from model)
(experimental)
(%)
(r,) (kg.m-3.h 1)
(rx) (kg.m-3.h -1)
0.77
193
2.110 -2
1.910 2
+ 10
0.70
195
1.810 -2
1.910 -2
-- 5
0.47
23
7.710 -3
8.410 -3
-- 9
0.47
68
1.3 10 -2
1.3 10 -2
0
0.46
45
1.110 -2
1.110 2
0
0.46
21
7.210 -3
6.510 -3
+ 10
0.24
25
6.010 3
6.610- 3
-- 10
0.15
23
4.210 -3
5.010 3
--16
0.09
31
2.910 -3
2.610 -3
+ 10
3.5.4 Continuous Cultures in Cylindrical Photobioreactors
Nine experiments were performed in a radially illuminated cylindrical photobioreactor with a radius of 0.05 m (volume of 71) and incident light fluxes
FR ranging between 20 and 200 W.m-2 in the visible spectrum [-51]. The pH was
equal to 9.5 and the temperature was 36 ~
The previous model for the growth of Spirulina platensis in a radially
illuminated cylindrical reactor (i.e. Eqs. 47, 48, 82-89 in Table 3) has been
integrated for these nine continuous cultures and compared with the experimental results obtained given the general mass balance equation in steady state:
(rx) = DCx
(98)
where D is the culture dilution rate.
The model calculation of the mean volumetric biomass growth rate has been
done using the gM and Kj values identified on rectangular photoreactors by
Cornet et al. [46, 73] and recalled above. The results are given in Table 5. The
model calculations and experimental data agree closely for biomass concentrations ranging between 0.09 and 0.77 kgm-3; the mean deviation for the nine
experiments is less than 10%.
Special attention must be paid to the predictivity of the proposed models
since the cylindrical photoreactor simulations were obtained with the same
parameters identified for rectangular reactors. Thus, parameters determined
with incident fluxes ranging between 4 and 20 W.m-2 remain valid between 20
and 200 W.m-2, representing a domain of variation of a factor of 50.
195
Table 5. Comparison between the Spirulina mass volumetric growth rate in biomass calculated by
the proposed model and experimentally determined on continuous cultures in a cylindrical photobioreactor for different biomass concentrations and incident radiant energy fluxes (Permission fi'om
Elsevier)
Biomass
Incident radiant
Volumetric growth
Volumetric growth
Standard
Concentration
energy flux
rate in biomass
rate in biomass
deviation
Cx (kg.m-3)
FR (W.m-2)
(from model)
(experimental)
(%)
(r,) (kg.m-3.h 1)
(rx) (kg.m-3.h -1)
0.77
193
2.110 -2
1.910 2
+ 10
0.70
195
1.810 -2
1.910 -2
-- 5
0.47
23
7.710 -3
8.410 -3
-- 9
0.47
68
1.3 10 -2
1.3 10 -2
0
0.46
45
1.110 -2
1.110 2
0
0.46
21
7.210 -3
6.510 -3
+ 10
0.24
25
6.010 3
6.610- 3
-- 10
0.15
23
4.210 -3
5.010 3
--16
0.09
31
2.910 -3
2.610 -3
+ 10
3.5.4 Continuous Cultures in Cylindrical Photobioreactors
Nine experiments were performed in a radially illuminated cylindrical photobioreactor with a radius of 0.05 m (volume of 71) and incident light fluxes
FR ranging between 20 and 200 W.m-2 in the visible spectrum [-51]. The pH was
equal to 9.5 and the temperature was 36 ~
The previous model for the growth of Spirulina platensis in a radially
illuminated cylindrical reactor (i.e. Eqs. 47, 48, 82-89 in Table 3) has been
integrated for these nine continuous cultures and compared with the experimental results obtained given the general mass balance equation in steady state:
(rx) = DCx
(98)
where D is the culture dilution rate.
The model calculation of the mean volumetric biomass growth rate has been
done using the gM and Kj values identified on rectangular photoreactors by
Cornet et al. [46, 73] and recalled above. The results are given in Table 5. The
model calculations and experimental data agree closely for biomass concentrations ranging between 0.09 and 0.77 kgm-3; the mean deviation for the nine
experiments is less than 10%.
Special attention must be paid to the predictivity of the proposed models
since the cylindrical photoreactor simulations were obtained with the same
parameters identified for rectangular reactors. Thus, parameters determined
with incident fluxes ranging between 4 and 20 W.m-2 remain valid between 20
and 200 W.m-2, representing a domain of variation of a factor of 50.