Impact of disinfectant on the electrical outputs of urine-fed ceramic and membrane-less microbial fuel cell cascades

The application of microbial fuel cells in sanitation has demonstrated feasibility in supplying electricity and providing safety in underserved communities, especially at toilet blocks. Two different designs of urine fed MFC cascades, ceramic MFCs (c-MFC) and self-stratifying MFCs (s-MFC), have been employed in large-scale feasibility studies. As part of a pre-commercialisation approach, this study verified the resilience of each design when a commercial disinfectant was introduced into the system. Five different conditions, varying in concentrations (24.2 mM-604.5 mM) and the total volume (50-500 mL) of sodium hypochlorite disinfectant introduced, were tested. Upon adding the disinfectant, both types of MFC-cascades exhibited rapid power drops with response times lower than 5 min in all tested conditions, followed by relatively swift recovery times of up to 250 min. The volume of disinfectant introduced had a greater impact on power output than its concentration or dose. Comparing the two designs, the c-MFC demonstrated a much larger voltage drop, up to 0 mV, and shorter recovery time compared to the s-MFC under most test conditions, mainly attributed to the presence (c-MFC) or absence (s-MFC) of a membrane. Overall, both types of MFCs exhibited strong resilience to sodium hypochlorite additions, thereby highlighting the commercial potential of the technology towards safe off-grid sanitation.