A two-chamber microbial electrolysis cell (MEC) where exoelectrogens at the anode oxidise organic substrate and a small applied voltage (~0.4–0.8 V) drives proton reduction to hydrogen at the cathode. MECs convert wastewater BOD into a usable, storable energy carrier rather than electricity, with hydrogen yields that can approach the theoretical maximum (Logan et al. 2008).
Alleinstellungsmerkmale
Closes the wastewater-to-fuel loop: organic carbon goes in, clean H₂ comes out at the cathode. Applied bias of ≈ 0.4 V is roughly a third of the 1.23 V water electrolysis requires, because anode microbes supply the balance of the thermodynamic work.
Funktionsweise
Anode chamber houses a Geobacter / Shewanella biofilm on carbon felt or graphite brush, oxidising acetate or wastewater BOD to CO₂, protons, and electrons. Electrons travel through the external circuit and a power supply that adds ~0.4–0.8 V; protons cross a CEM (Nafion or Selemion) into the cathode chamber. At a Pt/C, MoS₂, or biocathode, protons recombine with electrons to evolve H₂ gas, which is collected at the headspace.
Leistungsbereich
H₂ production rate0.3 – 3 L H₂ / L reactor / day
Cathodic H₂ recovery60 – 95 %
Coulombic efficiency40 – 90 %
Applied voltage0.3 – 0.8 V
Energy yield (over input)150 – 400 %
Forschungsstand
One of the most mature MES platforms, with a pilot-scale unit run on real winery wastewater (Cusick et al. 2011). Key remaining bottlenecks are platinum-free cathode catalysts and long-term operation without methanogenic crossover.
Reaktorgeometrie
Two acrylic or glass chambers (50 mL – 5 L each) separated by a CEM in a flat-flange clamp. Anode: carbon felt or graphite brush, projected area 25–500 cm². Cathode: Pt-coated carbon paper, MoS₂-modified carbon, or stainless mesh. Headspace gas-collection port on the cathode side. Reference electrode (Ag/AgCl) in the anode chamber for chronopotentiometry.
Anwendungen
- Wastewater-to-hydrogen at WWTPs
- Distributed clean-fuel production
- CO₂-neutral H₂ for fuel-cell vehicles
- Coupled treatment + energy recovery for breweries / distilleries
- Lab-scale bioelectrochemistry teaching platform
Aktives Volumen
0.1 – 5 L per chamber