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This study investigates reverse polarity biocathode culture (RPBC) for rapid preparation of nitrite-reducing bioelectrodes. RPBC leverages electrogenic bacteria to accelerate enrichment of reducing electroactive bacteria (EAB) through interspecies electron transfer and composite biofilm formation. Compared to direct biocathode culture (DBC), RPBC reduces enrichment time by 80%, increases electroactivity 12.4-fold, and enhances nitrite degradation rate 4.85-fold. The mechanism involves energy supply regulation via electrode potential and substrate concentration, with optimal performance at −0.3 V and 1500 mg COD/L acetate.

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What they did

System
MFC

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Abstract

The reverse polarity biocathode culture (RPBC) is a technology for the rapid preparation of biocathodes, which quickly enrich electroactive bacteria (EAB) in the microbial fuel cell (MFC) anode and then transform the electrode function from bioanode to biocathode by reversing bioelectrode polarity. However, the mechanism of RPBC is still unclear, and methods to regulate performance and ensure the long-term stability of cultured biocathodes have not been established. This study investigated the correlation between electrogenic bacteria and the target reducing EAB, from two aspects: energy supply and the formation of a composite biofilm. The results showed that electrogenic bacteria provided energy for the reducing EAB through interspecies electron transfer. This process could be regulated by changing the electrode potential and substrate concentration to obtain an optimized biocathode. In addition, the RPBC forms a composite biofilm of electrogenic bacteria and reducing EAB, which significantly improves the enrichment efficiency and the amount of reducing EAB (compared with a direct biocathode culture, respectively, shortening the enrichment time by 80%, increasing the electroactivity by 12.4 times, and increasing the nitrate degradation rate by 4.85 times). This study provides insights into regulating the performance and maintaining the long-term stability of RPBC-cultured biocathodes.

Keywords

BiofilmNitriteBacteriaMicrobiology

Identifiers

DOI
10.3390/pr13020509
Journal
Processes
Year
2025