Post-Treatment of CO₂ Emissions With Microalgae: Magnetic Field-Induced Improvements in an AirLift Photoreactor.

Atmospheric pollution from volatile organic compounds (VOCs) and rising global temperatures due to greenhouse gases (GHGs) emissions, such as carbon dioxide (CO2) pose significant threats to air quality and public health. Coupled biological systems can mitigate VOC emissions, generating CO2, which is then assimilated by microalgae. Static magnetic field (SMF) stimulation has been shown to enhance microalgal growth and CO2 fixation. This study evaluated the impact of SMF on CO2 fixation in an airlift photoreactor (ARL) following VOCs treatment in a semi-continuous stirred tank reactor (S-CSTR) processing toluene vapors. The ARL was exposed to SMF at 45 mT for 6, 4, and 2 h d-1. Results demonstrated a 96% increase in CO2 capture after 4 h of exposure, while removing 45% of the remanent toluene. The highest biomass increase (12%) occurred after 6 h of exposure, whereas total chlorophyll content peaked at 18.4 mg L-1 under 4 h of SMF, compared with 6.8 mg L-1 in the control. Therefore, 4 h exposure at 45 mT was identified as the optimal condition, balancing VOCs reduction, CO2 mitigation, and high pigment production. Microalgal cultures under SMF present a promising and versatile approach for air pollution control and carbon valorization, offering potential economic benefits through biomass applications and supporting circular economy initiatives.