(160r) Algae Turf Filter Photobioreactor Designs, Operation and Testing for Algae Cultivation for Space Explorations

Attached growth cabinet-type reactors were designed for cultivation of Chlorella vulgaris on synthetic wastewater as a nutrient source. Two designs are compared in this study for biomass production. Algae cultivation requires biological, chemical and physical factors for algae biomass production. Biological factors in the algae culture inoculum are considered to minimize competition for resources with other predators and microorganisms by decontamination and sterilization. Chemical factors include the nutrients needed for growth at known concentrations determined in a previous study. Physical factors involve illumination for photosynthesis, which is measured as photosynthetic usable radiation (PUR). One reactor design has plates to hold water and algae in modules for water treatment and biomass production. Another design consists of drawers and plates with baffles and a weir to hold water for nutrients for attached algae growth. The modules or drawers are operated in similar to gas absorption column is operated, whereby the air and water flowrates are measured to deliver nutrients and carbon dioxide to the algae. For a laboratory scale set-up, an air pump can deliver air while water in a reservoir at the top was delivered by drop-wise gravity flow through a filter for delivering water. Engineering calculations on the mass transfer coefficient on the gas-water interface and biomass growth kinetic data evaluate the performance of the attached growth photobioreactor, as compared to a suspended growth photobioreactor at the laboratory scale. A system engineering analysis approach for the two designs reveals the essential attributes for operating them in international space station conditions. Biological factors suggested in the literature to enhance the growth of the algae on surfaces are also considered.