Operation of a continuous single stage process for CO2 capture
To evaluate CO2 capture when gas is injected directly into the microalgae culture, a continuous 2.2 L photobioreactor was operated. A gas with a composition of 70% N2 and 30% CO2 was injected into the photobioreactor, simulating biogas. Nitrogen was used at this step, instead of methane, for safety reasons. Gas injection was controlled on-line in order to provide a pH in the range 7.5e8.0. Gas recirculation (150 mL min?1) was applied to provide mixing of the culture medium in the photobioreactor, and to enhance gase-liquid mass transfer. Applied dilution rate was 0.06 d?1(feed flow of medium : 0.144 L d?1). Samples from photobioreactor were periodically taken to measure biomass and dissolved inorganic carbon (DIC) concentrations. Composition of gas entering and leaving the system was also determined.