Nitrogen removal with the physiological stratification of cathodic biofilm in air-cathode single-chamber microbial fuel cell under different external resistances

The aim of this study was to investigate the effect of external resistance on the physiological stratification of cathodic biofilms in the air-cathode single-chamber microbial fuel cell (MFC) during the nitrogen removal. The mature cathode biofilm of MFC after 13 cycles operation (-900 h) was sliced into five layers, each with a thickness of 20 to 30 lm, to determine the physiological stratification of the cathode biofilm. With the external resistance decreasing from 1000 to 10 52, the NH4+-N and total nitrogen removals was decreased from 90.3 +/- 9.0 % and 89.4 +/- 9.0 % to 75.3 +/- 8.0 % and 67.5 +/- 7.0 %, respectively. Ammonia -oxidizing bacteria was closer to the cathode under lower external resistance, while denitrifying bacteria dominated the community far from the cathode under different external resistances. Results from this study should be useful for understanding the nitrogen removal in the cathodic biofilm of MFC. CO 2023 Published by Elsevier Ltd.