Microalgae-based flue gas CO2 sequestration for cleaner environment and biofuel feedstock production: a review.

Anthropogenic CO2 emissions are the prime cause of global warming and climate change, promoting researchers to develop suitable technologies to reduce carbon footprints. Among various CO2 sequestration technologies, microalgal-based methods are found to be promising due to their easier operation, environmental benefits, and simpler equipment requirements. Microalgae-based carbon capture and storage (CCS) technology is essential for addressing challenges related to the use of industrial-emitted flue gases. This review focuses on the literature concerning the microalgal application for CO2 sequestration. It highlights the primary physiochemical parameters that affect microalgal-based CO2 biofixation, including light exposure, microalgal strain, temperature, inoculum size, pH levels, mass transfer, CO2 concentration, flow rate, cultivation system, and mixing mechanisms. Moreover, the inhibition effect of different flue gas components including NOx, SOx, and Hg on growth kinetics is discussed to enhance the capacity of microalgal-based CO2 biofixation, along with deliberated challenges and prospects for future development. Overall, the review indicated microalgal-based flue gas CO2 fixation rates range from 80 mg L-1 day-1 to over 578 mg L-1 day-1, primarily influenced by physiochemical parameters and flue gas composition. This article summarizes the mechanisms and stages of microalgal-based CO2 sequestration and provides a comprehensive review based on international interest in this green technology.