eng International Academy of Ecology and Environmental Sciences Proceedings of the International Academy of Ecology and Environmental Sciences 2220-8860 2016-6-1 6 2 53 61 3 article M. Shabani 1 2 M.H. Sayadi 1 2 M.R. Rezaei 1 2 Environmental Sciences Department, University of Birjand, Birjand, Iran The limitation of fresh water and the exorbitant cost of land to grow such plants, algae are the most optimum organisms for CO2 bio-sequestration and also microalgae cultures avail many characteristics that make them an arguable option for higher productivities as compared to higher plants. The aim of this study was the sequestrate CO2 by Spirulina platensis and Chlorella vulgaris under the different levels of salinity and CO2. The highest growth rate obtained during the first 4 days and higher biomass concentration at CO2 concentration from 0.03% to 10% respectively. The significant (p less than 0.05) biomass productivity, growth rate and CO2 sequestration rate under different level of CO2 and EC between Spirulina platensis and Chlorella vulgaris were detected. The ultimate CO2 sequestration rate of Spirulina platensis and Chlorella vulgaris were 0.49 and 0.152 g/L/d in natural water respectively, although in artificial sea water 0.419 and 0.097 g/L/d were recorded at 10% CO2 concentrations respectively. http://www.iaees.org/publications/journals/piaees/articles/2016-6(2)/CO2-bio-sequestration-by-Chlorella-vulgaris.pdf green house gas microalgae Sea water natural water pure water