Microbial fuel cells (MFCs) have drawn much attention nowadays due to their potential application in generation of electricity from various forms of biomass. Moreover, MFCs also hold their practical promising application capabilities for the field of environmental sanitation. Another aspect, which is of concern is the greenhouse effect resulting from the significant increase in concentration of greenhouse gases (GHGs) in which methane plays the second key role (after carbon dioxide) in its global contribution to cause global warming. Hereby, it is believed that MFCs can be applied to diminish the methane emission from the freshwater wetland in general and in rice paddies in particular which are considered as important sources of methane.
In this work, it was reported for the first time that MFCs could be applied as a potential strategy for methane mitigation from freshwater wetlands from a technical point of view.
Sediment MFCs were developed focusing on improving electrode potentials to get a better operative performance. By using chemical and biological catalysts for the cathode, the cathodic potentials could obtain and remain at values of ca. + 400 mV vs. SHE. Hereby, the anodic potential could overcome the critical potential for methane formation/oxidation (-150 mV vs. SHE) and reach positive values during the experiment. However, the goal of reducing the methane production from a sediment reactor was not yet achieved. Important steps towards that goal have been set.
Basically, it has been illustrated that electric current can be generated by feeding citrate and dried rice straw, precursors of methane production in rice paddies, to the square type MFCs. This opens possibilities for applying MFCs to capture electrons from plant derived organic substrates in the mud phase. The square type MFC fed by citrate showed that 1 kg citrate can be converted to 3.9 kWh; whereas the square type MFC fed by dried rice straw displayed that 1 kg of straw can be converted to 0.129 kWh.
Finally, electricity generation in mud zones fed by plant root exudates was demonstrated. This shows that the concept of capturing electrons from substrates in the mud phase can be extended to an oxidation of electron donors set free by plants. This is a novel finding and has a great potential for approaching the mitigation of methane emissions from freshwater wetland.



Auteur: Hai Dang Son
Herkomst: CES (Centre for Environmental Sanitation) -CMS UGent
Referentie: Referentie