Performance and Microbial Community Analysis of an Electrobiofilm Reactor Enhanced by Ferrous-EDTA.

The biological reduction of ferrous ethylenediaminetetraacetic acid (EDTA-Fe-NO and EDTA-Fe) is an important process in the integrated electrobiofilm reduction method, and it has been regarded as a promising alternative method for removing NO from industrial boiler flue gas. EDTA-Fe-NO and EDTA-Fe are crucial substrates that should be biologically reduced at a high rate. However, they inhibit the reduction processes of one another when these two substrates are presented together, which might limit further promotion of the integrated method. In this study, an integrated electrobiofilm reduction system with high reduction rates of EDTA-Fe-NO and EDTA-Fe was developed. The dynamic changes of microbial communities in the electrobiofilms were mainly investigated to analyze the changes during the reduction of these two substrates under different conditions. The results showed that compared to the conventional chemical absorption-biological reduction system, the reduction system exhibited better performance in terms of resistance to substrate shock loading and high microbial diversities. High-throughput sequencing analysis showed that , and were the dominant genera (>25% each) during the process of EDTA-Fe-NO reduction. had the ability to endure the shock loading of EDTA-Fe, and the relative abundance of under abnormal operation conditions was up to 30.82%. was the main bacteria for reducing nitrate by electrons and the relative abundance still exhibited 16.11% under shock loading. Furthermore, higher microbial diversity and stable reactor operation were achieved when the concentrations of EDTA-Fe-NO and EDTA-Fe approached the same value (9 mmol·L).