Spirally wound microbial fuel cell
A bacterial fuel cell including at least one anode and at least two cathodes in liquid communication with a liquid to be treated, the at least one anode being separated from the at least two cathodes by at least first and second electrically insulating spacers and the at least one anode and the at least two cathodes being electrically connected across an external load and the at least one anode and the at least two cathodes being wound together generally in a spiral configuration together with at least a third electrically insulating spacer.
1. A bacterial fuel cell comprising:
at least one anode and at least two cathodes in liquid communication with a liquid to be treated, said at least one anode being separated from said at least two cathodes by at least first and second electrically insulating, water-side spacers and said at least one anode and said at least two cathodes being electrically connected across an external load; and
said at least one anode and said at least two cathodes being wound together generally in a spiral configuration together with at least a third, air side spacer providing a separation between adjacent layers of the spiral, a layer of the spiral being defined by at least one anode and its flanking cathodes, wherein
the air-side spacer has a thickness to permit airflow passageway between layers of the spiral; and the water side spacers define a separation between the anode and flanking cathodes through which the liquid to be treated flows; and wherein
sealing is provided between said at least two cathodes, whereby said at least one anode is enclosed inside an enclosure including said sealing and said at least two cathodes.
2. A bacterial fuel cell according to claim 1 , wherein said at least one anode and said at least two cathodes are formed of a flexible material.
3. A bacterial fuel cell according to claim 1 , wherein said electrically insulating spacers comprise plastic nets.
4. A bacterial fuel cell according to claim 1 , wherein said at least two cathodes are oxygen permeable.
5. A bacterial fuel cell according to claim 1 , wherein a multiplicity of electrical output connections is distributed along a length of said spiral.
6. A bacterial fuel cell according to claim 1 , wherein said at least one anode and said at least two cathodes each comprise:
a metal electrical conductor and
an electrically conductive coating at least between said metal electrical conductor and said liquid to be treated, said electrically conductive coating being operative to mutually seal said liquid and said electrical conductor from each other.
7. A bacterial fuel cell according to claim 6 , wherein said metal electrical conductor is coated with an electrically conductive coating.
8. A bacterial fuel cell according to claim 7 , wherein said coated metal electrical conductor of at least one of said at least two cathodes is water permeable.
9. A bacterial fuel cell according to claim 6 , comprising at least one conductive surface adapted for biofilm growth thereon, which conductive surface is in liquid communication with said liquid to be treated and is in electrical communication with said metal electrical conductor via said electrically conductive coating.
10. A bacterial fuel cell according to claim 6 , wherein said electrically conductive coating is adapted for biofilm growth on a surface thereof.
11. A bacterial fuel cell according to claim 9 , wherein said at least one conductive surface adapted for biofilm growth is defined by a fabric overlying a surface of said electrically conductive coating.
12. A bacterial fuel cell according to claim 9 , wherein said at least one conductive surface adapted for biofilm growth is defined by a conductive fabric, wherein said metal electrical conductor comprises a coated metal electrical conductor and said electrically conductive coating comprises an electrically conductive coating formed on said metal electrical conductor.
13. A bacterial fuel cell according to claim 12 , wherein said conductive fabric comprises carbon.
14. A bacterial fuel cell according to claim 6 , wherein said at least two cathodes each also comprises an oxygen permeable, liquid-impermeable layer adjacent said electrically conductive coating and wherein said oxygen permeable, liquid-impermeable layer is exposed to an oxygen-containing gas.
15. A bacterial fuel cell according to claim 14 , wherein said oxygen permeable, liquid-impermeable layer comprises silicone rubber.
16. A bacterial fuel cell according to claim 14 , wherein said oxygen permeable, liquid-impermeable layer comprises a micro-perforated film comprising a poly olefin such as polyethylene or polypropylene.
17. A bacterial fuel cell according to claim 6 , wherein said metal electrical conductor comprises a perforated planar element.
18. A bacterial fuel cell according to claim 1 , wherein at least one of said at least two cathodes includes an attachment layer.
19. A bacterial fuel cell according to claim 18 , wherein said attachment layer comprises a plastic fabric.
20. A bacterial fuel cell according to claim 6 , wherein said electrically conductive coating comprises a conductive plastic.
21. A bacterial fuel cell according to claim 6 , wherein said metal electrical conductor comprises copper.
22. A bacterial fuel cell according to claim 6 , wherein said metal electrical conductor comprises aluminum.
23. A wastewater treatment installation comprising a plurality of bacterial fuel cells according to claim 1 , wherein said plurality of bacterial fuel cells is arranged in a stacked configuration.
24. A wastewater treatment installation according to claim 23 , wherein said plurality of bacterial fuel cells is hydraulically connected in series.
25. A wastewater treatment installation according to claim 23 , wherein said plurality of bacterial fuel cells is hydraulically connected in parallel.
26. A wastewater treatment installation according to claim 23 , wherein said plurality of bacterial fuel cells is electrically interconnected.