Basic study related to oxygen production rate from Spirulina culture system

Abstract

The oxygen regeneration system is one of the most important subsystems in CELSS. Algae photosynthesis is useful for oxygen regeneration. In this study, in order to obtain basic knowledge regarding oxygen regeneration using algae, a culture system based on the turbidostat method was constructed. Culture experiments, using Spirulina platensis, were conducted for the purpose of investigating the relationship between oxygen production rate and cell density. Spirulina was cultured with several different cell densities and oxygen production rate, dilution rate and chlorophyll content were measured for each treatment. The maximum oxygen production rate was obtained with the highest cell density, but in spite of that, photosynthesis and growth were enhanced in the lower density treatments. In the algal suspension with high cell density, the obtainable light energy in the culture vessel decreased so drastically that photosynthesis of Spirulinamay have been inhibited. There was such a large amount of Spirulina cells in the culture vessel that despite the lower levels of photosynthesis, the oxygen production rate remained high. The chlorophyll content was less in the lower density treatments. The high light intensity may have caused the decrease in chlorophyll content.