Microbial Community Contributed to Novel Single-chamber Microbial Nitrogen Removal in Flat-panel Microbial Fuel Cells

摘要

The research suggests a novel single-chambered microbial nitrogen-removal in flat-panel air-cathode microbial fuel cells (FA-MFC). The FA-MFC successfully treated domestic wastewater without aeration and the effluent satisfied effluent quality standards of chemical oxygen demand (COD; 40 mg/L) and total nitrogen (TN; 20 mg/L) within a short hydraulic retention time (HRT) of 2.5 h. Microbial community analysis using Illumina MiSeq revealed that various bacterial populations involved in nitrification, denitrification, fermentation, sulfate reduction, and iron reduction were developed in the FA-MFCs. Four possible mechanisms for nitrogen removal were identified: (1) oxidation of ammonia (Nitrosomonadaceae) and nitrite (Nitrospiraceae) using oxygen penetrated through the cathode, (2) heterotrophic denitrification (e.g. Rhodocyclaceae) at both surfaces of the anode and cathode, (3) anaerobic ammonium oxidation (Brocadiaceae) at the anaerobic zone, and (4) autotrophic denitrification (Thiobacillus) at the surface of anode. Distribution of fermentation bacteria (e.g. Anaerolinaceae) showed that fermentative substrates produced from the hydrolysis of complex organics in unit 1. Some sulfate-reducing bacteria (e.g. Desulfobulbaceae) and iron-reducing bacteria (e.g. Geobacteraceae) may be able to transfer electron to anode electrodes. The FA-MNC system can be an innovative and sustainable domestic wastewater treatment process.