The Cultivation of Mixed Microalgae and CO2 Fixation in a Photo-Bioreactor

Microalgae is a form of prospective biomass energy. Cultivation of wild mixed microalgae is not only develop a new way for biomass energy production, but reduce the emission of carbon dioxide in flue gas, which is important to the alleviation of global climate change. In this study, wild mixed microalgae were cultivated in an airlift photo reactor. The effects of carbon oxide concentration, condition of illumination on growth of microalgae as well as the crude fat content in microalgae were investigated during 180 days cultivation. And the kinetic parameters of mixed microalgae were tested. The results showed that the microalgae growth rate could be greatly enhanced by feeding with CO₂ of flue gas. The growth rate of microalgae feeding with 10% CO₂ was four times of that feeding with air. Continuous illumination for 24 hr is beneficial for microalgae growth and stability of growth rate. The specific growth rate reached to 0.2 1/d, which was higher than that conditions of half illumination in one day. In the condition of same microalgae biomass and total photosynthetic active radiation, the accumulation of crude fat would benefit from decrease of radiation intensity and increase of light time. The CO₂ absorption by mixed microalgae obeyed the first order kinetics. The reaction constant was 0.015 1/min at the microalgae concentration of 1 g/L.