Abstract: A flow rectifying device is provided in a cultivation basin used in the cultivation of algae of the type in which there is a horizontal circulating flow of the cultivation water. The flow rectifying device avoids the formation of puddles or stagnant water and provides for uniform flow of the circulating water as the direction of flow changes at corners of the basin. The flow rectifying means includes a plurality of curved parallel fins for smoothly deflecting the flow of the circulating cultivation water and thereby prevents contamination of the cultivation liquid by preventing algae from being destroyed. The apparatus is particularly useful in cultivating blue-green algae of the genus Spirulina and other aquatic lower algae.

Abstract: A process for continuous cultivation of microorganisms capable of producing protein while adjusting the pH of the culture broth to a constant value with ammonia, characterized in that the growth rate of the microorganisms is maintained constant by maintaining the rate of consumption of ammonia constant.