Biotechnology Carbon Capture and Storage (CCS) by Mix-culture Green Microalgae to Enhancing Carbon Uptake Rate and Carbon Dioxide Removal Efficiency with Variation Aeration Rates in Closed System Photobioreactor

Abstract

Carbon dioxide (CO2) sequestration by green microalgae is receiving increased attention in alleviating the impact of increasing CO2 in the atmosphere. The goal of this study was to explore the capacity of mixed culture green microalgae Chlorella sp, Scenedesmus obliquus, and Ankistrodesmus sp. as carbon capture and storage agent to enhance CO2 uptake rate and CO2 removal efficiency which was observed at elevated CO2 aeration rates of 2, 5, and 8 L min-1 supplied to vertical photobioreactor continuously in batch system culture. The operation condition of this research were 6.5-7.5 pH, temperature of 300C, light intensity  of 4000 lux with 16 hours light period and 8 hours dark period, and high pure CO2 elevated level of 5 to 18 (concentration in %; v/v in the aeration gas) as inorganic carbon. The maximum CO2 removal efficiency of the mix culture was 59.80% when the biomass was obtained at 4.90 gL-1 and CO2 flow rate (Lmin-1) of 5 vvm in a vertical photobioreactor. The value of CO2 removal efficiency improved by almost 200% and 120% as compared to that in the low and high aeration rate (2 Lmin-1 and 8 Lmin-1) respectively. The CO2 up take rate of a mixed culture reach 979.62 mg carbon L-1day-1, which was enhancing by 3-fold in high aeration rate (8 Lmin-1). The results showed that the CO2 removal efficiency and carbon uptake rate was related to biomass concentration and aeration rate of CO2 supplied.