ABSTRACT
The effect of CO2 and the manner of CO2 offer on the growth rate and maximual cell density of ultro-high density culture of Chaetoceros mulleri in the photobioreactor were studied in the work. The amount of CO2 offered to the culture was controlled by the parameter of pH value in the culture. Furthermore the growth kinetics of Chaetoceros muller in the photobioreactor was studied. The results showed requirement of CO2 by the cells and the increase of pH in the culture were the key limiting factors to the growth, when a high cell concentration in the culture was reached. The offer of CO2 could improve the statute of CO2, could control the pH in the culture and increase the growth rate and maximum cell density. The results from the experiments of CO2 offer manner showed different efficiency to growth was resulted from differences of CO2 offer manner. The best way is mixing the CO2 and air before the CO2 was offered to the culture.