Development of a process for efficient use of CO2 from flue gases in the production of photosynthetic microorganisms

A new methodology to use efficiently flue gases as CO2 source in the production of photosynthetic microorganisms is proposed. The CO2 is absorbed in an aqueous phase that is then regenerated by microalgae. Carbonated solutions could absorb up to 80% of the CO2 from diluted gas reaching total inorganic carbon (TIC) concentrations up to 2.0 g/L. The pH of the solution was maintained at 8.0–10.0 by the bicarbonate/carbonate buffer, so it is compatible with biological regeneration. The absorption process was modeled and the kinetic parameters were determined. Anabaena sp. demonstrated to tolerate pH (8.0–10.0) and TIC (up to 2.0 g/L) conditions imposed by the absorption step. Experiments of regeneration of the liquid phase demonstrated the feasibility of the overall process, converting CO2 into organic matter. The developed process avoids heating to regenerate the liquid whereas maximizing the efficiency of CO2 use, which is relevant to achieve the commercial production of biofuels from microalgae. Biotechnol. Bioeng. 2012; 109:1637–1650. © 2012 Wiley Periodicals, Inc. A new methodology to use efficiently flue gases as a CO2 source in the production of photosynthetic microorganisms is proposed. The CO2 is absorbed in carbonated solutions, up to 80%, at pH ranges of 8.0–10.0, then the liquid phase is depurated biologically. Anabaena sp. tolerated conditions imposed by the absorption step, converting CO2 into organic matter. The developed process maximizes the efficiency of CO2 use, which is relevant to achieve the commercial production of biofuels from microalgae.