CO2 Capture of the Gas Emission, Using a Catalytic Converter and Airlift Bioreactors with the Microalga Scenedesmus dimorphus

A process composed by a catalytic converter and three sequential Airlift photobioreactors containing the microalga Scenedesmus dimorphus was studied to capture CO2, NOx, and CO from emissions of a steam boiler which was burning diesel. The catalytic converter transformed to CO2 a maximum of 78% of the CO present in the combustion gas. The effects of shear rate, light intensity, and light/dark cycles on the biomass growth of the algae were studied. It was observed that at low shear rates (Re ≈ 3200), a high productivity of 0.29 gcel L−1 d−1 was obtained. When the microalga was exposed to 60.75 µmol·m−2·s−1 of intensity of light and a light/dark cycle of 16/8 h, a maximum productivity of 0.44 gcel L−1 d−1 and a maximum CO2 fixation rate 0.8 g CO2 L−1·d−1 were obtained. The maximum CO2 removal efficiency was 64.3%, and KLa for CO2 and O2 were 1.2 h−1 and 3.71 h−1 respectively.