Flue gas waste heat affects algal liquid temperature for microalgal production in column photobioreactors

Abstract

To explore the effects of waste heat (50–170°C) from steel plant flue gas on the column photobioreactor algal liquid temperature for microalgal production, a flue gas‐microalgal liquid heat transfer model was developed that simulated the microalgal growth environment for flue‐gas carbon dioxide (CO2) fixation. The simulation results showed that the influence of high‐temperature flue gas weakened with the increasing microalgal liquid temperature due to enhanced evaporation and heat dissipation. Increasing the flue gas temperature and aeration rate resulted in a higher microalgal liquid temperature up to a maximum increase of 4.16°C at an ambient temperature of 25°C, an aeration rate of 2 L/min, and a flue gas temperature of 170°C. In an experiment on the effect of incubation temperature on the growth rate of microalgae, at an optimal temperature of 35°C, the Chlorella sp. PY‐ZU1 growth rate exhibited a remarkable increase of 104.7% compared to that at 42.5°C. Therefore, modulating the flue gas conditions can significantly increase the microalgal growth rate for CO2 fixation, making it a promising approach to increase biomass production for efficient carbon utilization.