Low-grade heat energy driven microbial electrosynthesis for ethanol and acetate production from CO₂ reduction

Microbial reverse-electrodialysis electrosynthesis cell (MREC) is an attractive strategy for wastewater treatment and valuable chemicals production from CO₂ reduction. Herein, one innovative MREC is proposed to drive CO₂ conversion to ethanol and acetate with low-grade waste heat energy coupled with thermolytic solutions (e.g., NH₄HCO₃ solution) as driven power sources. In such MREC, the maximum ethanol and acetate accumulated concentration of 5.23 ± 0.35 and 2.85 ± 0.38 mM are obtained, catalyzed by Clostridium ljungdahlii ERI-2 with production rates of 130.75 ± 8.75 and 137.92 ± 7.92 mmol m⁻² d⁻¹, respectively. Moreover, the current as the key parameter for the CO₂ conversion, which can be controlled by the salinity ratios of NH₄HCO₃ solutions and medium of Clostridium ljungdahlii ERI-2. This work for the first time proves the potential of the MREC for simultaneous biofuels production, CO₂ reduction, wastewater treatment and waste heat energy utilization.