Immobilized Microalgae-Based Photobioreactor for CO2 Capture (IMC-CO2PBR): Efficiency Estimation, Technological Parameters, and Prototype Concept

Microalgae-mediated CO2 sequestration has been a subject of numerous research works and has become one of the most promising strategies to mitigate carbon dioxide emissions. However, feeding flue and exhaust gas into algae-based systems has been shown to destroy chloroplasts, as well as disrupt photosynthesis and other metabolic processes in microalgae, which directly limits CO2 uptake. CO2 biosequestration in existing photobioreactors (PBRs) is also limited by the low biomass concentration in the growth medium. Therefore, there is a real need to seek alternative solutions that would be competitive in terms of performance and cost-effectiveness. The present paper reports the results of experiments aimed to develop an innovative trickle bed reactor that uses immobilized algae to capture CO2 from flue and exhaust gas (IMC-CO2PBR). In the experiment, ambient air enriched with technical-grade CO2 to a CO2 concentration of 25% v/v was used. The microalgae immobilization technology employed in the experiment produced biomass yields approximating 100 g DM/dm(3). A relationship was found between CO2 removal rates and gas volume flux: almost 40% of CO2 was removed at a feed of 25 dm(3) of gas per hour, whereas in the 200 dm(3)/h group, the removal efficiency amounted to 5.9%. The work includes a determination of basic process parameters, presentation of a developed functional model and optimized lighting system, proposals for components to be used in the system, and recommendations for an automation and control system for a full-scale implementation.

Automated summary

Microalgae-mediated CO2 sequestration is an effective strategy to mitigate carbon dioxide emissions, but feeding flue and exhaust gas into algae-based systems can limit CO2 uptake. This study developed an innovative trickle bed reactor using immobilized algae to capture CO2, with promising results in terms of biomass yields and CO2 removal rates. Basic process parameters, a functional model, optimized lighting system, component proposals, and automation and control system recommendations were also provided for potential full-scale implementation.