Microbial Electrolytic Carbon Capture for Carbon Negative and Energy Positive Wastewater Treatment

Energy and carbon neutral wastewater management is a major goal for environmental sustainability, but current progress has only reduced emission rather than using wastewater for active CO₂ capture and utilization. We present here a new microbial electrolytic carbon capture (MECC) approach to potentially transform wastewater treatment to a carbon negative and energy positive process. Wastewater was used as an electrolyte for microbially assisted electrolytic production of H₂ and OH^- at the cathode and protons at the anode. The acidity dissolved silicate and liberated metal ions that balanced OH^-, producing metal hydroxide, which transformed CO₂ in situ into (bi)carbonate. Results using both artificial and industrial wastewater show 80-93% of the CO₂ was recovered from both CO₂ derived from organic oxidation and additional CO₂ injected into the headspace, making the process carbon-negative. High rates and yields of H₂ were produced with 91-95% recovery efficiency, resulting in a net energy gain of 57-62 kJ/mol-CO₂ captured. The pH remained stable without buffer addition and no toxic chlorine-containing compounds were detected. The produced (bi)carbonate alkalinity is valuable for wastewater treatment and long-term carbon storage in the ocean. Preliminary evaluation shows promising economic and environmental benefits for different industries. (Figure Presented).