Optimization of Environmental Conditions to Maximize Carbon Dioxide Sequestration through Algal Growth

The micro-alga Chlorella vulgaris was cultivated under a variety of environmental conditions in various culture media solutions to optimize growth rate and biomass productivity. Efforts during this work investigated growth at the micro-scale in an air-lift bubble system with the goal of interpreting performance characteristics for application to a larger tubular Photo-bioreactor. Maximum growth rates and biomass yields were 0.65 d-1 and 2.003 g biomass/L and achieved in seven days using urea in de-ionized water under a 24:0 Photoperiod (Light:Dark). Additionally, growth rates and biomass yields of 0.65 d-1 and 1.964 g biomass/L were achieved over the same time period using commercial fertilizers in Charcoal Filtered Tap Water, indicating that the alga is robust and tolerant of a wide range of environmental conditions, including nutrient composition and water type. CO2 tolerance was investigated to determine the utility of the alga in power plant flue gas remediation schemes. The alga grew in all CO2-in-Air concentrations between ambient air and 50% CO2 with maximum growth occurring at concentrations between ambient levels and 20% CO2-in-Air. Greatest growth was observed in the culture using 15% CO2-in-Air, indicating this particular alga may be appropriate for power plant flue gas remediation (13-16% CO2 in flue gas).