CO 2 , NO x and SO x removal from flue gas via microalgae cultivation: A critical review

Flue gas refers to the gas emitting from the combustion processes, and it contains CO 2 , NO x , SO x and other potentially hazardous compounds. Due to the increasing concerns of CO 2 emissions and environmental pollution, the cleaning process of flue gas has attracted much attention. Using microalgae to clean up flue gas via photosynthesis is considered a promising CO 2 mitigation process for flue gas. However, the impurities in the flue gas may inhibit microalgal growth, leading to a lower microalgae‐based CO 2 fixation rate. The inhibition effects of SO x that contribute to the low pH could be alleviated by maintaining a stable pH level, while NO x can be utilized as a nitrogen source to promote microalgae growth when it dissolves and is oxidized in the culture medium. The yielded microalgal biomass from fixing flue gas CO 2 and utilizing NO x and SO x as nutrients would become suitable feedstock to produce biofuels and bio‐based chemicals. In addition to the removal of SO x , NO x and CO 2 , using microalgae to remove heavy metals from flue gas is also quite attractive. In conclusion, the use of microalgae for simultaneous removal of CO 2 , SO x and NO x from flue gas is an environmentally benign process and represents an ideal platform for CO 2 reutilization.