Microbial Fuel Cells for Wastewater Treatment - Biotechnologies and Biomimetics for Civil Engineering - page 408

obtaining a higher electron transfer rate and electron recovery between microbial
cells and electrodes. In 1999, a breakthrough in MFCs was published by Kim and
his colleagues, who showed that exogenous mediators were not necessary to be
added to transfer electrons from bacterial cells to electrodes and they developed
the first mediator-less MFC using a Fe(III)-reducing bacterium, Shewanella
putrefaciens IR-1 (Kim et al. 1999 ). The cell suspension of Shewanella putre-
faciens IR-1 was able to generate current without redox mediator in the presence
of lactate as the main carbon source. Another important bacterium Geobacter
sulfurreducens can transfer electrons to electrode in the absence of the mediators
with high current generation (Bond and Lovley 2003 ) and has become an
important issue on MFC research. After the discovery of mediator-less MFCs,
scientists have become more interested to do research on MFCs, especially in
wastewater treatment because mediator-less MFCs provide a more practical and
promising approach to recover electricity from organic waste and wastewater
through microbial systems (Liu and Logan 2004 ; Min and Logan 2004 ). Presently
many research laboratories have been engaged in improving MFC technologies to
enhance the electricity production and efficient removal of wastewater by
designing different configurations of MFCs such as single chamber MFC, tubular
MFC (Rabaey et al. 2005b ), stacked MFC (Aelterman et al. 2006 ) and also
membrane-less MFC (Feng et al. 2013b ). The advancement of research on MFCs
in the future may be the solution to energy scarcity and the clean-up of wastewater.
Thus, MFCs have received a great deal of attention as a novel green technology for
alternative energy generation and wastewater treatment.
18.3 Design and Operations of MFCs
An appropriate design and architecture is of great significance for improving
performance in MFC systems (Du et al. 2007 ; Pant et al. 2010 ). The mode of
operation and components of a typical two-chamber and a single-chamber MFC
are shown in Fig. 18.1 .
18.3.1 Two-Chamber MFC Systems
Traditional two-chamber MFCs consist of an anaerobic anode chamber and an
aerobic cathode chamber separated by a proton exchange membrane (PEM) or
sometimes a salt bridge, allowing proton transfer from anode to cathode and
preventing oxygen diffusion to the anode chamber, as shown in Fig. 18.1 a.
Regardless of the problems in scale-up, the dual-chamber MFCs have remained
the most popular devices for testing microbial activity and optimizing materials.
There are a variety of designs and structures occurred based on the principles of
two chamber MFC systems, e.g., the widely used and inexpensive H-type MFCs