Biosensor nanostructures based on dual-chamber microbial fuel cells for rapid determination of biochemical oxygen demand and microbial community analysis

A low-cost dual-chamber microbial fuel cell (MFC) was constructed as a biosensor for the rapid determination of biochemical oxygen demand (BOD) in domestic sewage. The operating conditions were optimized during the operation of the MFCs. The changes in the microbial community structure in the anode compartment were analyzed by 16S rRNA gene sequencing technology. The results indicated that the MFCs-BOD biosensor reached a steady state (maximum voltage of around 550 mV) within 1 week. The optimal working conditions were K-3[Fe(CN)(6)] of 50 mm, anolyte pH of 7, and external resistance of 1000 omega. The maximum current density and highest power density can be as high as 221.88 mA/m(2) and 78.77 mW/m(2), respectively. Compared with other studies, the start-up period of this MFCs-BOD biosensor was shorter (96-192 h), the determination range was wider (50-500 mg/L), and the determination time was short (within 3 h). The MFCs-BOD biosensor can accurately determine the BOD content of sewage water samples. The results of 16S rRNA gene sequencing showed that the anodic microbial community after the domestication changed significantly compared with the original inoculated anaerobic activated sludge flora, and the dominant electrogenic bacteria with the highest relative abundance belonged to Proteobacteria and Enterobacteria. The device has reliability and applicability in the BOD determination in actual domestic sewage, and this study provides a solid foundation for the future application of MFCs-BOD biosensor in the rapid determination of BOD in sewage.

Automated summary

A low-cost dual-chamber microbial fuel cell (MFC) was constructed as a biosensor for the rapid determination of biochemical oxygen demand (BOD) in domestic sewage. The MFCs-BOD biosensor reached a steady state within 1 week and showed high current and power density. Compared with other studies, this biosensor had a shorter start-up period, wider determination range, and faster determination time. Analysis of the microbial community structure revealed significant changes after domestication, with Proteobacteria and Enterobacteria being the dominant electrogenic bacteria. The results confirmed the reliability and applicability of the MFCs-BOD biosensor in determining BOD in sewage, laying a solid foundation for its future application.