9  EP 2 000 000 A1 10  vironment to generate electrical energy and wherein the anode electrode is in direct contact with the cath- ode chamber [0051] It may be preferred that the anode electrode comprise at least 20%, such as at least 30%, e.g. at least 40%, such as at least 50%, e.g. at least 60%, such as at least 70%, e.g. at least 80%, such as at least 90% of the cathode chamber surface, such as in the range of 30-90%, e.g. in the range of 40-80%, such as in the range of 50-70%, e.g. in the range of 50-60%, such as in the range of 60-70% e.g. in the range of 70-80%. [0052] As mentioned above it is an object of the present invention to simultaneously achieve pollution control and provide a sustainable energy production. In order to achieve an increased yield of electrical energy generated it is preferred that two or more microbial fuel cell or com- bined electrodes are connected, such as 3 or more, e.g. 4 or more, such as 5 or more, e.g. 10 or more, such as 20 or more, e.g. 50 or more, such as 100 or more, e.g. 150 or more, such as 200 or more, e.g. 300 or more, such as 400 or more, e.g. 500 or more as illustrated in figure 3. [0053] In a further embodiment of the present invention one microbial fuel cell or combined electrodes or the two or more microbial fuel cells or combined electrodes such as two or more, e.g. 3 or more, such as 5 or more, e.g. 10 or more, such as 20 or more, e.g. 50 or more, such as 100 or more, e.g. 150 or more, such as 200 or more, e.g. 300 or more, such as 400 or more, e.g. 500 or more may be submersed into the same anaerobic environment as illustrated in figure 5. [0054] The inventors of the present invention have fur- thermore provided a method for obtaining bio- energy. The method comprises the steps of: (i) submersing one or more anode electrode (s) and one or more cathode chamber (s), said cathode chamber comprising an inlet through which influent enters the cathode chamber, an outlet through which the effluent depart the cathode chamber, a cathode electrode and a electrolyte membrane and one or more combined electrodes into an anaerobic envi- ronment (ii) permitting microorganisms in the anaerobic en- vironment to oxidize reduced organic or inorganic material thereby producing a plurality of electrons and (iii) obtaining a voltage between the one or more an- ode electrode (s) and the one or more cathode elec- trode (s). GLYPH<3> [0064] The invention will now be described in further details in the following non- limiting examples. [0055] In the present context the term "bio- energy" re- lates to electrical energy made available from materials derived from biological sources, such as the organic and inorganic matter, present in the anaerobic environment, in which the one or more anode electrode (s) and the one or more cathode chamber (s) are submerged. It is an em- bodiment of the present invention the organic matter may either by inherently present in or added to the anaerobic environment. [0056] In a further embodiment of the present inven- tion, it is preferable the microorganisms are either inher- ently present in or added to the anaerobic environment. It is preferred that the microorganisms are anaerobic or facultative anaerobic or a combination hereof in order to tolerate the anaerobic environment and thus be capable of oxidizing compounds present in such anaerobic envi- ronment. [0057] In an embodiment of the present invention, the anaerobic microorganisms may be Geobacter species, Desulfuromonasspecies or other types of anaerobic mi- croorganisms and the facultative anaerobic microorgan- isms may be Shewanella species or other types of fac- ultative anaerobic microorganisms. Said microorgan- isms may comprise pure cultures or mixed cultures or a combination thereof. [0058] It is an object of the present invention that the microbial fuel cell and the combined electrode as de- scribed above may be used for the generation of electrical energy. In other preferred embodiments the microbial fu- el cell and the combined electrode may be used for bi- oremediation wherein e.g. specific soil contaminants are degraded by bacteria to compounds less contaminating or to not contaminating compounds. [0059] In the present context the term "bioremediation" relates a process wherein an environment altered by con- taminants is returned to its original condition. GLYPH<3> [0060] In yet an embodiment of the present invention the microbial fuel cell and the combined electrode may be used as a biosensor to e.g. monitor the conversion of organic matter in specific environments such as anaer- obic environments. [0061] In the present context the term "biosensor" re- lates to a device or devices that use biological materials to monitor the presence of e.g. various chemicals in an environment by electrical, thermal or optical signals. [0062] In a further embodiment of the present invention the microbial fuel cell and the combined electrode may be used for the production of bio- hydrogen. In the present context the term "bio- hydrogen" relates to hydrogen pro- duced via biological processes with an additional poten- tial provided electrochemically. [0063] It should be noted that embodiments and fea- tures described in the context of one of the aspects of the present invention also apply to the other aspects of the invention. 6 Increasing energy yield Method for obtaining bio- energy