Silver removal and microbial community structure in microbial fuel cells

Background Silver (Ag) removal, electric current generation and the microbial community responsible were investigated in two replicate dual-chamber microbial fuel cells (MFCs). The MFCs were inoculated with activated sludge and operated for electricity generation over 90 days. Results Silver was efficiently removed from synthetic wastewater at the cathode chamber of the MFC and the precipitated particles on the cathode electrode were verified as Ag using X-ray diffraction and scanning electron microscopy analysis. The MFCs achieved a maximum power density of 1850 +/- 25 mW m(-2) and a maximum Ag removal of 99.8%. Furthermore, Illumina high-throughput sequencing of bacterial 16S rRNA genes showed that both MFCs shared the same dominant bacterial phyla, namely Synergistetes, Bacteroidetes, Proteobacteria and Firmicutes, with bacteria belonging to Butyricicoccus, Petrimonas, Desulfomicrobium and Desulfovibrio and large numbers of unassigned genera. Conclusions The dual-chamber MFCs provided an efficient method for concurrent Ag removal and energy generation, and effectively removed and recovered Ag from various wastewater streams even at low Ag concentrations. However, continued Ag precipitation on the electrode surface during long-term operation could lead to a deterioration in the performance of the MFC and an increase in internal resistance. (c) 2022 Society of Chemical Industry (SCI).