Enrichment of sulfur-oxidizing bacteria using S-doped NiFe2O4 nanosheets as the anode in microbial fuel cell enhances power production and sulfur recovery

Microbial fuel cells (MFCs) have great promise for power generation by oxidizing organic wastewater, yet the challenge to realize high efficiency in simultaneous energy production and resource recovery remains. In this study, we designed a novel MFC anode by synthesizing S-doped NiFe2O4 nanosheet arrays on carbon cloth (S10-NiFe2O4@CC) to build a three-dimensional (3D) hierarchically porous structure, with the aim to regulate the microbial community of sulfurcycling microbes in order to enhance power production and elemental sulfur (S-0) recovery. The S10-NiFe2O4@CC anode obtained a faster start-up time of 2 d and the highest power density of 4.5 W/m(2) in acetate-fed and mixed bacteria-based MFCs. More importantly, sulfide removal efficiency (98.3 %) (initial concentration of 50 mg/L S2-) could be achieved within 3 d and sulfur (S-8) could be produced. Microbial community analysis revealed that the S10-NiFe2O4@CC anode markedly enriched sulfur-oxidizing bacteria (SOB) and promoted enrichment of SOB and sulfatereducing bacteria (SRB) in the bulk solution as well, leading to the enhancement of power generation and S-0 recovery. This study shows how carefully designing and optimizing the composition and structure of the anode can lead to the enrichment of a multifunctional microbiota with excellent potential for sulfide removal and resource recovery.