Electrolysis-Enhanced Anaerobic Digestion of Wastewater Shows Promise

Strategic Insights -

A recent study published in Bioresource Technology has demonstrated the potential of electrolysis-enhanced anaerobic digestion of wastewater. Researchers in Montreal, Canada, have shown that the addition of electrodes to anaerobic reactors can increase methane production and improve reactor stability. The study found that the application of a voltage of 2.8-3.5 V created micro-aerobic conditions, which facilitated hydrolysis of synthetic wastewater and reduced the release of hydrogen sulfide to the biogas. The oxygen created by electrolysis was also converted to methane by hydrogenotrophic methanogens, increasing the net methane production.

Key Takeaways:

  • The study demonstrates enhanced methane production from wastewater in laboratory-scale anaerobic reactors equipped with electrodes for water electrolysis.
  • The electrodes were installed in the reactor sludge bed and a voltage of 2.8-3.5 V was applied, resulting in a continuous supply of oxygen and hydrogen.
  • The oxygen created micro-aerobic conditions, which facilitated hydrolysis of synthetic wastewater and reduced the release of hydrogen sulfide to the biogas.
  • A portion of the hydrogen produced electrolytically escaped to the biogas and improved its combustion properties, while another part was converted to methane by hydrogenotrophic methanogens.
  • The presence of oxygen in the biogas was minimized by limiting the applied voltage.
  • Successful treatment of both low and high strength synthetic wastewaters was demonstrated at a volumetric energy consumption of 0.2-0.3 Wh/L.
  • Methane production was increased by 10-25% and reactor stability was improved in comparison to a conventional anaerobic reactor.

Statistics:

  • Volumetric energy consumption: 0.2-0.3 Wh/L
  • Applied voltage: 2.8-3.5 V
  • Methane production increase: 10-25%
  • Reactor stability improvement: Improved in comparison to a conventional anaerobic reactor

Sources:

  • Tartakovsky, B., et al. "Electrolysis-enhanced anaerobic digestion of wastewater." Bioresource Technology, vol. 102, no. 10, 2011, pp. 5685-5691.
  • National Research Council. Biotechnology Research Institute.