Kinetics on the CO2 fixation by batch culture for blue green algae.

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Batch cultivation of blue green algae Spirulina platensis in the photobioreactor was carried out to evaluate the culture as CO2 fixation system. The authors kinetically analyzed the effect of CO2 and NH3 concentration in the culture on CO2 fixation and biomass productivity ofthe algae. The obtained results are summarized as follows;1) The productivity of the algae was slightly increased, when the NaHCO3 concentration was raised to between 32-64 (g/l) in comparison with ordinary cultivation (16g/l).2) The growth of the algae was smooth on the culture when both NH3 and NO3 were used as the nitrogen source. In this case, the absorption rate of NH3-N was about 20 (mg/(l·d)). When NH3 was the only nitrogen source, the obtained maximum growth rate was 0.147 (g/(l·d)) at 20 (mg/l) of initial NH3-N concentration, and productivity of the algae was reduced by about 1/2-1/3 of the ordinary cultivation. A 200 (mg/l) of the initial NH3-N concentration damaged the growth of the biomass.3) The C/N ratio, which obtained the maximum CO2 fixation rate, ranged from 10 to 20 and the average volumetric mass transfer coefficient value, KCO2La, was 0.005 (1/h).For wastewater treatment using algae, the concentration and composition control of the influent nitrogen source will be one of the most important problems.
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