Preliminary Study on Biomitigation Green House Gas Carbon Dioxide in Closed System Bubble Photobioreactor: Relationship Among the Mass Transfer Rate and CO2 Removal Efficiency in High Level of CO2

Emission of carbon dioxide (CO2) is a major contributor to global warming. Biofixation of CO2 by microalgae in photobioreactors seems to be a promising strategy for CO2 mitigation. The research to determine the overall mass transfer coefficient (kLa) has been done to find the way on biomitigation CO2 emission by using biologically Carbon Capture and Sequestration method. This research was conducted according to green microalgae Scenedesmus obliquus activity, which is cultivated in a bubble photobioreactor through the mass transfer process that assumed adequate mixing occurs. Flow rate of CO2 that supplied to the system were 2 L/min, 5 L/min and 8 L/min, when each rate flowed into the photobioreactor with high CO2 concentration (v/v) of 2%, 5% and 10%. The highest CO2 removal efficiency occurred at culture that supplied with an CO2-enriched air flow rate of 5 L/min. The kLa (CO2) value is the highest in 0.3582/day at 2% CO2 concentration and flow rate of 2 L/min, while the lowest is in 0.0503/day at 5% CO2 concentration and flow rate of 8 L/min. In terms of solubility is inversely proportional to the flow rate, the less carbon dioxide is dissolved at the rate of 8 L/min as well as the value of the kLa. The results showed that the variation of flow rate will affect the amount of mass transfer coefficient, growth rate and cell biomass. Higher flow rate decreases kLa value as well as CO2 removal efficiency.