title: Microbial Electrolytic Carbon Capture for Carbon Negative and Energy Positive Wastewater Treatment.
abstract: 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.
authors.affiliation: †Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States.
authors.forename: Lu
authors.initials: L
authors.lastname: Lu
authors.affiliation: †Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Huang
authors.affiliation: ‡Institute of Marine Sciences, University of California, Santa Cruz, California 95064, United States.
authors.forename: Greg H
authors.initials: GH
authors.lastname: Rau
authors.affiliation: †Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States.
authors.forename: Zhiyong Jason
authors.initials: ZJ
authors.lastname: Ren
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D002021:Buffers; D002244:Carbon / Q000032:analysis*; D057965:Carbon Sequestration; D004553:Electric Conductivity; D004566:Electrodes; D004572:Electrolysis / Q000379:methods*; D004573:Electrolytes / Q000737:chemistry; D006859:Hydrogen; D006863:Hydrogen-Ion Concentration; D007477:Ions; D013816:Thermodynamics; D062065:Wastewater / Q000737:chemistry* / Q000191:economics; D018508:Water Purification / Q000191:economics / Q000379:methods*
chemical_list: D002021:Buffers; D002244:Carbon; D004573:Electrolytes; D006859:Hydrogen; D007477:Ions; D062065:Wastewater