Biomedical Engineering Reference
In-Depth Information
the amount of CO 2 available is smaller, thus affecting algal growth. Results confirm that a
high initial pH acts as an inhibitory factor preventing algae from developing normally [8].
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18 0
160
16 0
250
14 0
12 0
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10 0
15 0
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10 0
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80
Chlorella Vulgaris
Chlorella Fusca
n 0 = 1.84 mg l -1
μ = 0.0241 h -1
K = 292.6 mg l -1
R 2 = 1.000
n 0 = 1.11 mg l -1
μ = 0.0115 h -1
K = 35.9 mg l -1
R 2 = 0.972
60
n 0 = 0.40 mg l -1
μ = 0.0357 h -1
K = 169.9 mg l -1
R 2 = 0.994
n 0 = 0,68 mg l -1
μ = 0.0177 h -1
K = 3.0 mg l -1
R 2 = 0.978
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0
0
0
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0
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Ti m e ( h )
Ti m e ( h )
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15 0
15 0
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10 0
10 0
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0
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0
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0
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150
n 0 = 7.79 mg l -1
μ = 0.0158 h -1
K = 54.7 mg l -1
R 2 = 0.910
Scenedesmus Obliquus
150
n 0 = 3.86 mg l -1
μ = 0.0137 h -1
K = 32.8 mg l -1
R 2 = 0.965
Scenedesmus Acutus
100
n 0 = 2.00 mg l -1
μ = 0.0289 h -1
K = 327.8 mg l -1
R 2 = 0.998
n 0 = 1.86 mg l -1
μ = 0.0272 h -1
K = 263.1 mg l -1
R 2 = 0.998
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0
0
0
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Ti m e ( h )
Ti m e ( h )
Figure 4. Microalgal growth as a function of time for different initial pH values. (▲) pH = 6.5; ( ) pH
= 7.9. (—) Logistic model fittings (T = 20.8 ºC).
4.2.2. Temperature Influence
Comparing the values of the model parameters for the experiments performed at pH = 6.5
and two different temperatures (24.6 and 20.8 o C), it can be concluded (Figure 2 and Figure
4) that although the variation of the specific growth rate of biomass,μ, is casual, the
maximum biomass concentration, K , increases with temperature.
At 20.8 ºC, it was possible to observe that the pH increased from 6.5-6.6 to 7.0-7.1, after
about 190 h operation, not reaching values so high as at 24.6 ºC (Figure 3). The lower
production of biomass at 20.8 ºC originates a lower impact on the initial pH.
The variation of kinetic parameters due to temperature variation can be also associated to
environmental stresses, as, according to Becker [8], living organisms like algae are extremely
susceptible to changes occurring in the environment.
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