Investigating microbial interactions in dual chamber microbial fuel cells using a hybrid substrate of synthetic wastewater and human urine

Microbial fuel cells (MFC) are emerging as a sustainable technology for wastewater treatment, utilizing microbial communities to transform waste substrates into valuable resources. The electrochemical behavior and dynamics of the microbial community inhabiting MFCs that utilize synthetic wastewater mixed with real human urine as anolyte have not been explored much. In this study electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were harnessed to investigate the electrochemical performance and microbial population dynamics through 16 s metagenomic sequencing. Synthetic wastewater and varying dilutions of real human urine served as an anolyte, while acidic water(pH -2) as a catholyte across different batches of MFC. Three distinct batches were operated with anolytes that had urine concentrations of 20 %, 50 %, and 75 %, respectively. The CV demonstrated that when bacteria proliferate and biofilm develops gradually, the voltammograms region under the curve expands, a phenomenon that can be correlated to the anode's increasing capacitance. According to EIS assessments, the development of bacteria across the surface of the anode substantially reduces the impedance. The findings demonstrate that human urine contributes to essential ions and organic compounds, promoting microbial diversity and enhancing electron transfer processes. • MFCs use synthetic wastewater and human urine as mixed substrates for efficient, sustainable wastewater treatment. • CV and EIS were employed to study microbial activity and electron transfer dynamics. • Batch experiments using 20 %, 50 %, and 75 % urine concentrations showed marked differences in biofilm formation and electrochemical performance. • Higher urine concentration enhanced microbial diversity, strengthened biofilm formation, and lowered anode impedance.