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.