Analysis of denitrification performance and microbial community structure in a bio-electrochemical reactor under different current densities with wheat-rice stone powder

Abstract

Nitrate widely exists in water pollution and is the most stable form of nitrogen pollution. This study investigated the effect of the current density (CD) and the wheat-rice stone powder (WP) on denitrification performance, microbial diversity and enzyme activity in a bio-electrochemical reactor (BER). It was found that an optimum CD of 200 mA/m2 and the addition of WP significantly improved the nitrate removal rate constant compared with the control group (12.28 d−1 versus 9.75 d−1) and remarkably reduced the intermediate accumulation of nitrite. The application of both optimum CD and WP enhanced the microbial diversity and catalytic activity of nitrate reductase (Nar) and nitrite reductase (Nir). The most dominant microbial taxa in our reactor were Methyloversatilis, Methylotenera, and an unclassified genus of the family Methylophilaceae. Moreover, WP allowed the denitrifiers to better withstand the stress of high CD. This study presented results supporting the use of an optimum CD and natural mineral addition to improving the performance of the denitrification process within a BER.

Nano‐α‐Fe2O3 for enhanced denitrification in a heterotrophic/biofilm‐electrode autotrophic denitrification reactor

“…Sphingobium was the most dominant genus in B1, followed by Arenimonas , Acinetobacter , Thauera , and Pseudomonas . These genera were the key microorganisms in the denitrification process (Liu & Hu, 2022; Tian et al, 2021). However, the relative abundance of Sphingobium , Arenimonas , and Acinetobacter decreased dramatically in B2 and B3, which might be the reason that these genera were intolerant to the applied current.…”