Eflects of Aeration Volume on the Growth of Marine Chlorella in Culture

It is well known that aeration is an important practice in the cultivation of fish or plankton, and is commonly used by many aquaculturists. Practice of the aeration is simple but the mechanisms are complicated. Since HIRATA designed the movable aerator in 1969, study on the biological features of the aeration has become more clamorous. In this experiment, direct (Exp. I) and indirect (Exp. II) effects of aeration volume upon the growth of marine Chlorella were observed. All the experiments were carried out by using 2 l polyethylene bottles with 1 liter of culture medium. HIRATA's inorganic medium-II (HIRATA ; 1964) and active sludge as an organic medium based on soy-cake particles (HIRATA, et al.; 1973) were used in Exp. I and II, respectively. The air volume was subdivided into six rates ranging from 72 to 5040 liters per day. As a control experiment, soda-lime was employed for removing carbon dioxide from the air supplied. In Exp. I, growth of Chlorella at the rates of 72, 288, 720 and 1440 liters of air supply per day were 18, 42, 44 and 49×10^<6> cells/ml, respectively. Therefore, optimum air volume was estimated to be about 300 l/day from those results. In Exp. II, the Chlorella grew up to 4.4×10^<6> cells/ml in the medium of air supplied sludge, but no growth was found in the tank prepared with the sludge with no air supplied