Metabolic Regularity And Growth Kinetics Of Key Nutrients In Chlorella Growth

Chlorella vulgaris has a wide application prospect in medicine, health products and bio-energy industry. In order to get high production of Chlorella vulgaris through the method of high density cultivation, optimizations on design of photobioreactors and cultivation technology of Chlorella vulgaris were developed. Affecting elements in Chlorella vulgaris cultivation were studied from the following aspects:1. A rectangular airlift loop photobioreactor was employed to produce Chlorella vulgaris. The concentration curves of the key elements including N, P, K, Ca, Mg and Fe were measured every day during the cultivation in order to investigate the metabolic laws. The results indicated that the concentration of biomass based on the dry weight increased more and more slowly. The concentration of nitrogen was depleted within 70 hours; iron and phosphorus dropped to a very low concentration after 96 hours. The concentration of magnesium and calcium were no longer declining after 80 hours, while the concentration of potassium kept unchanged. Most of the key elements are depleted in 96 hours, and different element consumption rates are obtained. Although lack of nutrients at last, the Chlorella vulgaris kept growing slowly by sufficient CO2 and illumination.2. A tubular photobioreactor was used to produce Chlorella vulgairs in the experiment. On the condition of different irradiance and light time ratio, we observed the growth dynamics by analyzing the growth rate of Chlorella vulgaris. The results showed that when the light intensity was less than 370 ?mol·m-2·s-1, the growth rate of Chlorella vulgaris increased with the increasing of light intensity and light time, but when the light intensity was more than 542 ?mol·m-2·s-1, the result was the opposite. The chlorophyll fluorescence activity was decreasing with increasing light intensity and light time. The saturated intensity of Chlorella vulgaris is approximately 200 ?mol·m-2·s-1, and the suppressed light intensity of Chlorella vulgaris is around 500 ?mol·m-2·s-1. Decreasing the light intensity or light time ratio could increase the chlorophyll fluorescence activity.