Enhanced denitrification by coupling microbial electrolysis cell (MEC) and hydrogenotrophic denitrification (HD) by employing iron wool as an electrode

초록

Microbial electrolysis cells (MECs) represent an advanced bioelectrochemical technology for sustainable hydrogen production and wastewater treatment. By utilizing electroactive microorganisms, MECs facilitate redox reactions that drive hydrogen evolution and contaminant removal under low-energy input. This study investigates the application of iron wool as a cathode in MEC-driven hydrogenotrophic denitrification, emphasizing its dual role as an electrode material and redox mediator. The oxidation of iron wool released ferrous ions (Fe2+) and other intermediates, enhancing electron transfer and promoting microbial nitrate reduction. Four MECs were operated in fed-batch mode for 20 days under different external voltages (0.5-1.0 V) with an initial NO3--N concentration of 50 mg/L. Among the setups, MEC-3 (0.8 V) exhibited the highest H2 production and achieved 99.4 % nitrate removal, demonstrating optimal conditions for hydrogenotrophic denitrification. Microbial community analysis through 16S rRNA sequencing revealed distinct population shifts, with Pseudomonadota as the predominant phylum (55.3-68.9 %) across experimental groups. These findings underscore the effectiveness of iron wool as a cost-efficient electrode material, enhancing MEC performance through Fe2+mediated microbial processes. This study provides valuable insights into integrating iron-based electrodes for improved nitrogen removal in bioelectrochemical wastewater treatment systems.

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