A single-chamber membraneless microbial fuel cell exposed to air using Shewanella putrefaciens

Microbial Fuel Cells (MFCs) are bio-electrochemical devices which convert the chemical energy content of organic fuels into electricity, thanks to the ability of anode respiring bacteria to give electrons to the anode. This result is usually achieved under anaerobic conditions, obtained with a sealed anode chamber. Despite this, Shewanella oneidensis has been recognized by many authors to obtain the same results in presence of air. Furthermore, another member of the Pseudomonaceae family, Shewanella putrefaciens, has also shown the capability to catalyze the cathodic oxygen reduction. In this work the capability of S. putrefaciens to work under both anaerobic and micro-aerobic conditions was exploited using a simple and cheap undivided MFC without separators and contacted with air. The presence of S. putrefaciens allowed to produce current and power in the presence of air using cheap compact graphite cathodes and carbon felt anodes. The utilization of horizontal cathode increased current output. It was found that Shewanella putrefaciens is likely to act as biocatalyst also for the cathodic process