Development of an innovative ring-shaped cultivation system for a land-based cultivation of marine macroalgae

Marine macroalgae become increasingly important as a regenerative source of biomass for the production of food, pharmaceuticals, cosmetics and energy. An increasing and environmentally sound utilization of algae requires a closed, land-based cultivation, not limited to coastal or offshore areas. Within this study, segmental and ring-shaped cultivation vessels were developed and compared to tumble cultivation in a circular tank. The development of these innovative approaches also considered economic efficiency, adaptability, handling and reliability. The growth rates achieved by cultivating the red algae P. palmata and C. crispus and the green alga U. lactuca over a test period of 7 d were used to evaluate these experimental models. Mean growth rates of P. palmata and C. crispus in the ring-shaped cultivation model were slightly decreased whereas growth rate of U. lactuca was similar or increased compared to tank cultivated algae. The developed ring-shaped cultivation system distinctly lowered variable costs by reducing the necessary volume of cultivation medium. An increased control of the cultivation process was achieved by separating the supply of CO2 and nutrients, and the temperature control from agitation.