1 EP 2 000 000 A1 2  Description FIELD OF THE INVENTION [0001] The present invention relates to a novel micro- bial fuel cell construction. In particular the present inven- tion relates to a microbial fuel cell (MFC) comprising an anode electrode and a cathode chamber, wherein both the anode electrode and the cathode chamber are to be submersed into an anaerobic environment to generate electricity from organic matter in the anaerobic environ- ment. GLYPH<3> [0002] Limiting the dependency on fossil fuels and low- ering the amount of pollution generated, constitute a ma- jor challenge to modern society. Bioprocesses wherein organic matter is converted into bio- energy simultane- ously achieve the objective of pollution control and sus- tainable energy production. Such bioprocesses may in- clude methanogenic anaerobic digestion to produce methane, hydrogen fermentation to produce hydrogen and MFC’s to produce bioelectricity. Anaerobic diges- tions of e.g. industrial and agricultural wastewater which comprise high levels of easily degradable organic matter to methane is a well known process employed at full- scale plants all over the world. The methanogenic anaer- obic digestion technology, comprise however an obvious drawback as approximately 70% of the energy produced during conversion of methane to electricity is lost in gen- erators as heat. Further to this, the hydrogen fermenta- tion technology also suffers form severe inefficiencies, as it at best, utilize only about 15% of the energy content in organic matter. Accordingly the most promising tech- nology for energy production from organic matter, is the MFC which has been of interest to researchers around the world for the past decades. Although MFC’s generate a lower amount of electrical energy than hydrogen fuel cells, a combination of both electricity production and e.g. wastewater treatment may reduce the cost of treating primary effluent wastewater [0003] MFC’s are devices that directly convert micro- bial metabolic power generated from the degradation of organic matter into electrical energy via both biotic- and abiotic catalysts. The MFC’s disclosed in prior art may be composed of two chambers; an anode chamber where the oxidation of organic compounds takes place by mi- croorganisms under anaerobic condition and a cathode chamber where an oxidant such as oxygen or ferriccya- nide is reduced under aerobic condition. The cathode electrode is generally either immersed in a phosphate buffer or ferricyannide solution, or open to dry air. [0004] One of the most promising applications of the MFC technology described in prior art is the generation of electrical energy from i.e. wastewater and other unde- sirable substrates. Several studies on electricity produc- tion from artificial or real domestic wastewater, animal wastewater, food wastewater, and recently hydrolysate from corn stover biomass has been conducted and for this purpose several different types of MFCs has been developed both for batch and continuous mode opera- tions. [0005] Accordingly, the two most predominant benefits of using the MFC technology for power generation from degradable organic matter is that: (i) it can theoretically extract more energy from organic matter compared to other related technologies as no intermediate process is necessary for electricity generation and (ii) it can be used as a green treatment technology by completely oxidizing organic matter in wastewater to carbon dioxide with a minimum emission of air pollutants. [0006] The use however, of the MFC’s disclosed in pri- or art still remains limited for fieldapplication as difficulties of applying the MFC technology to natural environments exist. When applying conventional MFC’s in e.g. waste- water treatment, a steady flow of wastewater needs to be pumped into the anaerobic chamber to feed the bac- teria, which accordingly is expensive, take up a lot of space and most importantly limits the use of the MFC technology. [0007] Consequently, there exists a need for an im- proved MFC construction wherein the construction costs have been reduced and wherein the MFC may easily be employed in both natural and artificially constructed en- vironments. [0008] Accordingly, the aim of the present invention is to provide a MFC that solves the above mentioned prob- lems of the prior art with an improved construction, wherein the MFC may be employed in both natural and artificially constructed environments. [0009] In an aspect of the present invention, the MFC comprises: (i) an anode electrode (ii) a cathode chamber, said cathode chamber com- prising an inlet through which an influent enters the cathode chamber, an outlet through which an efflu- ent depart the cathode chamber, a cathode electrode and an electrolyte permeable membrane, wherein both the anode electrode and the cathode cham- ber are to be submersed into an anaerobic environment to electrical energy. GLYPH<3> [0010] In another aspect of the present invention, a combined electrode is provided. The combined electrode comprises: (i) an anode electrode (ii) a cathode chamber, said cathode chamber com- prising an inlet through which an influent enters the PRIOR ART SUMMARY OF THE PRESENT INVENTION 2