A sustainable integration of removing CO2/NOx and producing biomass with high content of lipid/protein by microalgae

Due to the boost of CO2/NOx emissions which cause environmental pollution, processes that remove such pollutants from flue gas have attracted increasing attention in recent years. Among these technologies, biological CO2/NOx emission reduction has received more interest. Microalgae, a kind of photosynthetic microorganism, offer great promise to convert CO2/NOx to biomass with high content of lipid and protein, which can be used as feedstock for various products such as biodiesel, health products, feedstuff and biomaterials. In this paper, biological CO2/NOx removing technologies by microalgae, together with the products (such as biofuel and protein) and their economic viability are discussed. Although commercial applications of microalgae for biodiesel and protein products are hampered by the high production cost of biomass, the use of CO2/NOx from flue gas as carbon and nitrogen sources can reduce the cost of biomass production, which makes these technologies more competent for real-life applications. Moreover, it is projected that the increasing in CO2 allowances will lead to further reduction in the cost of biomass production, which especially favors related products with lower values such as biodiesel. Furthermore, by combining various process optimization and integration, biorefinery is proposed and considered as the crucial component for the sustainable and economically feasible bulk applications of microalgae biomass.(c) 2022 Published by ELSEVIER B.V. and Science Press on behalf of Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences.