In this paper the utilization of the cyanobacteria Anabaena sp. in carbon dioxide removal processes is evaluated. For this, continuous cultures of this strain were performed at different dilution rates: alternatives for the recovery of the organic matter produced being also studied. A maximum CO2 fixation rate of 1.45 g CO2 L-1 day(-1) was measured experimentally, but it can be increased up to 3.0 g CO2 L-1 day(-1) outdoors. The CO2 is mainly transformed into exopolysaccharides, biomass representing one third of the total organic matter produced. Organic matter can be recovered by sedimentation with efficiencies higher than 90%, the velocity of sedimentation being 2 . 10(-4) s(-1). The major compounds were carbohydrates and proteins with productivities of 0.70 and 0.12 g L-1 day(-1), respectively. The behaviour of the cultures of Anabaena sp. has been modelized, also the characteristics parameters requested to design separation units being reported. Finally, to valorizate the organic matter as biofertilizers and biofuels is proposed. (C) 2009 Published by Elsevier Ltd.