Microbial fuel cell unit, use thereof, and microbial fuel cell arrangement

Abstract

The present invention relates to a microbial fuel cell (MFC) unit, which comprises at least one cathode, at least one anode, which is arranged at a distance from the cathode, preferably in direction of gravity, the anode being in free contact with a surrounding medium, provided that the number of cathodes or anodes is more than one, the anode(s) and cathode(s) being connected with each other through an external electrical circuit. The fuel cell unit comprises also locating means for positioning the unit within the surrounding medium, and the fuel cell unit is free from any membranes located between the cathode(s) and the anode(s).

Claims

1. Microbial fuel cell arrangement comprising at least two microbial fuel cell (MFC) units, where each unit comprises at least one cathode, at least one anode, which is arranged at a distance from the cathode, preferably in direction of gravity, the anode being in free contact with a surrounding medium, provided that the number of cathodes or anodes is more than one, the anode(s) and cathode(s) being connected with each other through an external electrical circuit, locating means for positioning the unit within the surrounding medium, wherein the fuel cell units are free from any membranes located between the cathode(s) and the anode(s) and where each unit is physically connected, detachably, with at least one other unit.

2. Arrangement according to claim 1, wherein in the microbial fuel cell unit the at least one cathode is flat and sheet-like, having a first horizontal large surface which can be arranged in contact with a catholyte, and a second horizontal large surface which is at least partly arranged in contact with the surrounding medium.

3. Arrangement according to claim 1, wherein the at least one anode is brushlike, has a honeycomb structure or is in form of a hollow perforated body.

4. Arrangement according to claim 1, wherein the at least one anode may be a flat sheet-like anode, arranged parallel with the at least one cathode.

5. Arrangement according to claim 1, wherein in that in the microbial fuel cell unit the number of anodes is higher than the number of cathodes.

6. Arrangement according to claim 5, wherein unit comprises one cathode and a plurality of anodes.

7. Arrangement according to claim 1, wherein the unit comprises a plurality of anodes, which are arranged in connection with one common anode current collector, or each individual anode is arranged in connection with its own anode current collector.

8. Arrangement according to claim 1, wherein the unit comprises at least two anodes, which are in contact with a common anode current collector.

9. Arrangement according to claim 1, wherein the locating means comprises at least one floating support, such as a buoy.

10. Arrangement according to claim 1, wherein the locating means comprises attaching means and fixed supports, such as poles.

11. Arrangement according to claim 1, wherein the locating means is arranged to position the cathode in contact with the surface of the surrounding medium.

12. Arrangement according to claim 1, wherein each unit comprises an anode current collector and a cathode current collector, and the anode current collectors and the cathode current collectors are in electrical connection with each other.

13. Arrangement according to claim 1, wherein the cathodes of the units are connected to a common cathode current collector and the anodes of the units are connected to a common anode current collector.

14. Arrangement according to claim 1, wherein each unit comprises either an anode current collector or a cathode current collector, and either the cathodes of the units are connected to a common cathode current collector or the anodes of the units are connected to a common anode current collector.

15. Use of an arrangement according to claim 1 for treating surrounding medium, which is a body of water including natural waters, such as rivers, lakes, ponds, and wastewater.

16. Use of an arrangement according to claim 1 for treating surrounding medium, which is wastewater selected from domestic wastewater; municipal or agricultural wastewater; effluent from an industrial process selected from pulp and paper, oil and gas, mining, food or beverage, pharmaceutical manufacturing, textile manufacturing, chemical manufacturing, power production, goods or electronics manufacturing, medical waste.

17. (canceled)

18. (canceled)

Description

[0042] In the following, the invention will be described in more detail with reference to the appended schematic drawings, in which

[0043] FIG. 1 shows schematically one embodiment of the MFC unit according to the present invention,

[0044] FIG. 2 shows schematically another embodiment of the MFC unit according to the present invention,

[0045] FIG. 3 shows schematically yet another embodiment of the MFC unit according to the present invention, and

[0046] FIG. 4 shows schematically an embodiment of the arrangement according to the present invention.

[0047] In FIG. 1 is shown schematically one embodiment of the present invention. The microbial fuel cell unit 1 comprises a cathode 2, which is an air cathode. The surface of the first side 2 of the cathode 2 is in contact with air. The cathode 2 is arranged in connection with a cathode current collector 5.

[0048] The MFC unit 1 comprises also a plurality of anodes 3, which are arranged in the direction of gravity at a distance from the cathode 2. All the anodes 3 of the MFC unit 1 are arranged in connection with an anode current collector 4. Between the anode current collector and the cathode current collector is arranged a separator 6, which prevents short circuit.

[0049] The MFC unit 1 comprises also a locating means 7, in this case a floating support, e.g. of Styrofoam. The locating means 7 is arranged to position the first side 2 of the cathode 2 in contact with air. In practice, this means that the MFC unit floats on the surface of the liquid medium while producing electricity and reducing the amount of organic substances in the liquid medium.

[0050] In FIG. 2 is shown schematically another embodiment of the MFC unit according to the present invention. The MFC unit 10 comprises a number of cathodes 11. The locating means comprises a net and buoys 13, 13 arranged on the outer periphery of the net. The cathodes 11 are connected to the net, which prevents the movement of the cathodes 11 in relation to each other. The net and the buoys 13 position the cathodes 11 on the surface of the liquid medium.

[0051] The MFC unit 10 comprises also one anode 14, which is made of carbon fiber material with a high surface area. The anode 14 is also connected to the net or to the frames of the cathodes. In this manner the position and distance of the anode 14 from the cathodes 11 is maintained constant.

[0052] In FIG. 3 is shown schematically yet another embodiment of the MFC unit according to the present invention. The MFC unit 20 comprises a cathode 21, which is made of carbon fiber felt. The carbon fiber felt is fixed on a ring support 22, which functions simultaneously as a locating means. The MFC unit comprises further a plurality of anodes 23 which are a connected to the ring support 22. The cathode 21 and the anodes 23 are physically connected with electrical wires to an external electrical circuit (not shown). The ring support 22, which can be made of floating and insulating polymer material, positions the MFC unit 20 on the surface of the liquid medium and guarantees that the first side of the cathode 21 is in contact with air.

[0053] In FIG. 4 is shown schematically an embodiment of the arrangement according to the present invention. The arrangement comprises a plurality of individual MFC units 30. Each MFC unit 30 comprises one cathode 31 and a plurality of anodes 32. The MFC units 30 are connected together in such a manner that each MFC unit is connected to at least one other MFC unit. The MFC units may be connected by using nets, ropes, chains or other suitable means.

[0054] Even if the invention was described with reference to what at present seems to be the most practical and preferred embodiments, it is appreciated that the invention shall not be limited to the embodiments described above, but the invention is intended to cover also different modifications and equivalent technical solutions within the scope of the enclosed claims.