Effect of microbial fuel cell operation time and membrane thickness on the disinfection efficacy of electrochemically synthesised catholyte from urine

Abstract Microbial fuel cells (MFCs) offer an excellent solution to tackle some of the major challenges currently faced by humankind: sustainable energy sources, waste management and water stress. Besides producing useful electricity from urine, ceramic MFCs can also generate biocidal catholyte in-situ. The MFCs performance and the catholyte quality are closely correlated. Owing to the potential applicability of the catholyte to deactivate solutions with high pathogenic content, it is necessary to obtain information concerning the effect that the MFC operating conditions have in the chemical characteristics contributing to the disinfection efficacy. In this work, the effect of the MFC operation time in the catholyte generated from ceramic MFCs of different thicknesses (10, 5 and 2.5 mm) has been chemically and microbiologically evaluated, during 42 days. The results show an increase in pH and conductivity with time, reaching pH 11.5. Flow cytometry and luminometer analyses of bioluminescent pathogenic E. coli exposed to the synthesised catholyte revealed killing properties against bacterial cells. A bio-electrochemical system, capable of electricity generation and simultaneous production of bactericidal catholyte from human urine is presented. The possibility to electrochemically generate in-situ a bacterial killing agent from urine, offers a great opportunity for water reuse and resource recovery for practical implementations.