| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 100 === Microalgae cultivated in open pond system have several difficulties to maintain optimum conditions for its growth, as a result biomass production is always lower than the expected amount. For increasing CO2 uptake, absorption tower was developed to supply CO2 into a photo-bioreactor. A proposed photo-bioreactor cultivation system consisted of a 42 L rectangular open tank equipped with 2-bubble columns of 1 L separately. From the bottom of each bubble column, air aeration was given at the flow rate of 1 vvm (1% CO2). Mixing performance inside the whole bioreactor had been examined through measuring the electric conductivity of water-salt solution taken from the tank. The flow pattern of the culture system was investigated with co-current and counter-current configurations. Counter-current flow pattern with external mixing treatment provided the shortest mixing time. Thus, we adopted counter-current configuration in our photo-bioreactor cultivation system.
In this study, Chlorella sp. were cultivated for 9 days. The reactor and working volume used in the batch cultivation were 42 L. Higher biomass production was obtained when using 2-bubble columns in comparison with 1-bubble column, there were 1.011 g/L and 0.900 g/L, respectively and calculated as an absolute biomass at 42.47 g and 37.81 g Then, in order to increase absolute biomass production, fed-batch strategy in which daily renewal rate is 20% since 4.5 day (the early stage of the stationary phase) was applied and the working volume increased to 84 L. Biomass production obtained is 0.593 g/L and the absolute biomass rose to 60.14 g. These results indicate that our proposed photo-bioreactor combined with the fed-batch cultivation can successfully enhance biomass production.
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