Algal Reactor for Life Support Systems

Algal systems are proposed for bioregenerative life support systems for long-term space missions. A net production of 500 g to 600 g of dry algae per man per day is required for oxygen regeneration, CO₂ absorption, water regeneration, nutrient removal and organic waste treatment. Irradiance (light intensity) is the determining factor in the design of an algal reactor, in the establishment of the system's maximum capacity, its physical dimensions, operating parameters, biomass concentration and algal production. Several models which describe the relationship between irradiance and algal growth and production are developed and evaluated. Of the three models developed, the macroscopic model based on the exponential relationship between irradiance and specific growth rate at the microscopic level proves to be the most compatible with the experimental results. The performance of the Algatron, a spin-type photosynthetic reactor, is described. Increased algal yield and efficiency of input energy conversion are attained in the Algatron by using a Lucalox light source and a reciprocating mixer designed to produce controlled turbulence in the algal culture.