Materials for Energy, Efficiency and Sustainability: TechConnect Briefs 2016Materials for Energy, Efficiency and Sustainability TechConnect Briefs 2016

Biofuels and Bioproducts Chapter 6

Potential for Green Algae Spirulina to Capture Carbon Dioxide from Gas Stream

M.S. Shurair, F. AlMomani, S. Judd, R.R. Bhosale, A. Kumar
Qatar University, Qatar

pp. 141 - 143

Keywords: air pollution, global warming, CO2 capturing, growth rate

Scientific evidences show that the earth’s climate is significantly affected because of the continuous emissions of greenhouse gases (GHGs). The increase in CO2 level in the atmosphere leads to global warming as CO2 is one of the potential GHGs. The concentration of CO2 in atmosphere rose by 30% from pre-industrial levels of 280 ppmv to 390 ppmv today, and it is expected that the CO2 concentration of the atmosphere will increase up to 550 ppmv by the year 2050. Physico-chemical process can be successfully employed to capture CO2 from flue gas streams of fossil fuel based power plants. However, the low efficiency and the high cost associated with these technologies limit their applicability. Micro-algae, on other hand, are among of the most productive biological systems for generating biomass and capturing carbon. Micro-algae's ability to transport bicarbonate into cells makes them well suited to capture carbon. Moreover, microalgae is considered an inexpensive technology as it does not require aeration and the growth cycle for most algae strains range from 1 to 3 weeks. There are still knowledge gaps in understanding the use of microalgae for CO2 capturing, including the capacity of CO2 capturing by different strains, the effect of pH, light intensity, water quality parameters and temperature on the performance of the process. The present study investigates the potential use of microalgae as CO2 capturing technology under different solution pHs, temperatures, and CO2 dosing. The study was conducted on fresh water with Spirulina as algal strain. Algae growth was followed at different temperatures, pHs and CO2 doses. Experiments were carried out in a 2 L batch photo-bioreactors with an initial algae concentration of 0.3 g/L and a temperatures of 8, 20 and 30 ◦C .The mixing of the cultures was achieved by bubbling air through the growth media to grantee high mass-transfer coefficient and efficient mixing. Algae growth was followed by measuring the optical density at 680 nm, and the efficiency of algae strain in capturing CO2 was followed by measuring the amount of CO2 utilized by algal strain after daily injection with different concentrations of CO2 (5%, 10% and 15%) for 5 minutes. For the experiments carried out at 30 ◦C, Spirulina injected with 10% CO2 showed the highest growth rate compared with blank solution. Algal strain dosed with 5 and 15% CO2 showed limited growth with respect to blank solution. The results indicate that algae can be considered as one of the efficient and low cost technology for CO2 capturing.