Modeling Growth of Chlorella Sorokiniana by Changing CO2 Nutrient Concentration and pH Dynamics by Convective Mass Transfer

Abstract

Changing pH in a system will have effects on almost all aspects of biological life in that system. Understanding how the pH changes in a system through the addition of CO2 over time is important to determine how life in that system will react. Additionally, algae has been well-researched due to its potential in biofuel production and water treatment. Understanding the role of carbon dioxide availability on the growth of algae is important to produce enough algae for these uses. This study explores both the modeling of dynamic pH effects through use of the convective mass transfer coefficient and the growth effects of CO2 on Chlorella sorokiniana. All algal growth experiments were conducted at a temperature of around 35º C, a light intensity of 234 µmol m-2 s-1, and a 12-hour light phase in a 24-hour cycle. Experiments were conducted with feed CO2 compositions between the concentration in air and 5%. A one parameter model was applied to data to find the growth rate. The trials showed that an excess composition of CO2 does not have a significant impact on the growth rate while CO2 limited trials give a decreased growth rate. The dynamic pH trials in different media were fit to a one parameter model. These pH experiments showed that the pH could be accurately modeled through the equations in this study and that the convective mass transfer coefficients for the absorption and desorption processes of CO2 were likely different.