NOVELTY - Preparing a microbial fuel cell involves establishing a biofilm of the microorganisms on and/or within the anode; subjecting the microorganisms of the biofilm to a growth stage by incorporating carbon-containing nutritive compounds in the anodic liquid medium during biofilm formation or after biofilm formation on the anode has been established, where the anodic liquid medium is contained in an anode chamber and is separated by a cation-selective permeable material from a cathodic liquid medium in contact with a cathode, where the anode and cathode are in electrical communication.    USE - For preparing a microbial fuel cell for generating electricity and hydrogen gas (claimed).    ADVANTAGE - The method provides a microbial fuel cell which can operate more efficiently and provide higher electrical power outputs. The method further provides a microbial fuel cell that operates more reliably with minimal power fluctuations even during a period of time when a feed level is lowered well below a critical threshold.    DETAILED DESCRIPTION - Preparing a microbial fuel cell involves inoculating an anodic liquid medium in contact with an anode of the microbial fuel cell with at least one types of microorganisms capable of functioning by an exoelectrogenic mechanism; establishing a biofilm of the microorganisms on and/or within the anode along with a substantial absence of planktonic forms of the microorganisms by substantial removal of the planktonic microorganisms during forced flow and recirculation conditions of the anodic liquid medium; and subjecting the microorganisms of the biofilm to a growth stage by incorporating carbon-containing nutritive compounds in the anodic liquid medium during biofilm formation or after biofilm formation on the anode has been established, where the anodic liquid medium is contained in an anode chamber and is separated by a cation-selective permeable material from a cathodic liquid medium in contact with a cathode, where the anode and cathode are in electrical communication. The anode comprises a form of elemental carbon (preferably carbon fiber, carbon paper, carbon foam, carbon cloth, carbon felt, carbon wool, carbon granules, carbon brushes, or graphite). The electrochemically reducible species is nitrate-containing compound or material, perchlorate-containing compound or material or metal-containing compound or material. INDEPENDENT CLAIMS are included for the following:    (1) microbial fuel cell comprising a biofilm of exoelectrogenic microorganisms on an anode of the microbial fuel cell, where the biofilm containing contains a portion of microorganisms capable of storing carbonaceous compounds or materials internally, and the biofilm is further characterized by a substantial absence of microorganisms possessing a planktonic tendency, where the anode is in electrical communication with a cathode, and the anode and cathode are in contact with, respectively, anodic and cathodic solutions that are separated by a cation-selective permeable membrane, and where the anode has a volume, and in anode chamber containing the anode has a volume, where ratio of the volume of the anode to the volume of the anode chamber is at least 0.5, and where the substantial absence of microorganisms possessing a planktonic tendency has been achieved by forced flow and recirculation of the anodic solution; and    (2) method for reductively processing electrochemically reducible species, involving operating a microbial fuel cell, where operation of the microbial fuel cell is conducted under the condition that the cathode is in contact with the electrochemically reducible species.    DESCRIPTION OF DRAWING(S) - The figure shows a microbial fuel cell recirculation set up with an air cathode.