Abstract
The performance of microbial electrochemical cells depends upon microbial community structure and metabolic activity of the electrode biofilms. Iron as a signal affects biofilm development and enrichment of exoelectrogenic bacteria. In this study, the effect of ferrous iron on microbial communities of the electrode biofilms in microbial fuel cells (MFCs) was investigated. Voltage production showed that ferrous iron of 100 μM facilitated MFC start-up compared to 150 μM, 200 μM, and without supplement of ferrous iron. However, higher concentration of ferrous iron had an inhibitive influence on current generation after 30 days of operation. Illumina Hiseq sequencing of 16S rRNA gene amplicons indicated that ferrous iron substantially changed microbial community structures of both anode and cathode biofilms. Principal component analysis showed that the response of microbial communities of the anode biofilms to higher concentration of ferrous iron was more sensitive. The majority of predominant populations of the anode biofilms in MFCs belonged to Geobacter, which was different from the populations of the cathode biofilms. An obvious shift of community structures of the cathode biofilms occurred after ferrous iron addition. This study implied that ferrous iron influenced the power output and microbial community of MFCs.
Highlights
Microbial electrochemical cell (MEC) has been admired as a versatile device that can be used for alternative energy generation, electrosynthesis, biosensor, and waste treatment (Hou et al, 2016; Liu et al, 2016a; Huang et al, 2017)
The results suggested that low concentration of Fe2+ could obviously improve electrochemical activity of microbial fuel cells (MFCs) in the start-up period
During another 15 days of operation, MFCs with 100 μM ferrous ion showed the best electrochemical characteristics compared to MFCs with 150 and 200 μM Fe2+, and MFCs without additional Fe2+ supplement (Figure 2)
Summary
Microbial electrochemical cell (MEC) has been admired as a versatile device that can be used for alternative energy generation, electrosynthesis, biosensor, and waste treatment (Hou et al, 2016; Liu et al, 2016a; Huang et al, 2017). The knowledge related to the effects of ferrous iron on performances of MFCs and microbial communities of electrode biofilms is less known.
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