Comparing Growth of Chlorella vulgaris in NaHCO3 and CaCO3 Solutions

Chlorella vulgaris, a freshwater photoautotrophic organism requires CO₂ and light to perform photosynthesis. Suspended growth microalgal reactor is a component of the BIOSYS Waste Management System for Mars, which will scrub cabin air from space camp by producing O₂ and removing CO₂. It will improve CO₂ removal efficiency of biorefineries. This system can be useful to operate biorefineries in urban areas and industrial plants (dual-use benefit).

Algae is also a good source of biofuels and nutrients (lipids & proteins). Chlorella vulgaris has been chosen because it grows quickly in a pH neutral environment. Its oil content is higher than crops. It has nutraceutical value as well.

This research is focused on growing microalgae in NaHCO₃ and CaCO₃ solutions instead of free CO₂. Continuous and intermittent air have been added to reactors to control pH of the algae suspension. Biomass concentration, pH, nitrogen and phosphorus consumption of algae have been recorded for two weeks. The reactor comprised of NaHCO₃ withcontinuous air shows a biomass productivity of 0.04 g algae/L/day. Nitrogen consumption was also higher for this reactor indicating healthy growth of microalgae.