Water / Kinetics / Biomass / Energy Conversion / Multidisciplinary / Biofilm / Electron Transfer / Bacteria / Methane / Current Density / Fermentation / Microbial Fuel Cell / Concentration gradient / Organic Compound / Power Density / Biofilm / Electron Transfer / Bacteria / Methane / Current Density / Fermentation / Microbial Fuel Cell / Concentration gradient / Organic Compound / Power Density