Method and apparatus for removing nitrates from water
First Claim
1. An apparatus for reducing nitrates in an aqueous solution, comprising:
- a) an electrochemical cell in which the aqueous solution containing nitrates is treated, said cell comprising a container;
b) an electrode system including a carbon fiber cathodic electrode, a carbon fiber anodic electrode, and a reference electrode, wherein all of said electrodes are immersed in the aqueous solution; and
c) an electronic control circuit including a means for impressing a voltage across said electrodes causing electrochemical reduction/oxidation reactions on the surfaces of said cathodic and anodic electrodes, and means for controlling said electrodes at a potential wherein nitrates are reduced to gaseous products, and further wherein hydrogen, oxygen and chlorine are not produced.
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Abstract
An apparatus for reducing nitrates in an aqueous solution includes an electrochemical cell having a container for containing the aqueous solution containing nitrates, a carbon fiber cathodic electrode, a carbon fiber anodic electrode, and a reference electrode immersed in the aqueous solution, and an electronic control circuit which impresses a voltage across the electrodes causing electrochemical reduction/oxidation reactions on the surfaces of the electrodes. The electrodes are at a potential such that nitrates are reduced to gaseous products, and further such that hydrogen, oxygen, chlorine, an other noxious substances are not produced. The cell may be a flow cell or a holding tank and apparatus of different size and capacity are disclosed. The apparatus is useful in reducing nitrates in any water system and is particularly useful in reducing nitrates in aquatic systems without harming aquatic life. One of the methods of the invention includes sequentially impressing three voltage signals between the reference electrode and the cathodic electrode, wherein each of the voltage signals are of different magnitudes, the voltage signals being a constant time-out period voltage, a sweep voltage and a constant working voltage.
94 Citations
23 Claims
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1. An apparatus for reducing nitrates in an aqueous solution, comprising:
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a) an electrochemical cell in which the aqueous solution containing nitrates is treated, said cell comprising a container; b) an electrode system including a carbon fiber cathodic electrode, a carbon fiber anodic electrode, and a reference electrode, wherein all of said electrodes are immersed in the aqueous solution; and c) an electronic control circuit including a means for impressing a voltage across said electrodes causing electrochemical reduction/oxidation reactions on the surfaces of said cathodic and anodic electrodes, and means for controlling said electrodes at a potential wherein nitrates are reduced to gaseous products, and further wherein hydrogen, oxygen and chlorine are not produced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of reducing nitrates in an aqueous solution, comprising the steps of:
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a) providing an electrochemical cell including a container for at least partially containing the solution; b) providing an electrode system including a carbon fiber cathodic electrode, a carbon fiber anodic electrode, and a reference electrode; c) arranging all of the electrodes in the container such that they can be submersed in the solution when the solution is introduced into the container; d) introducing the solution into the cell such that all of the electrodes are immersed in the aqueous solution; e) providing an electronic control circuit operably connected to the electrodes which controls the potential at the electrodes; and f) impressing a voltage across the electrodes, the voltage causing an electrochemical reduction/oxidation reaction on the surfaces of the cathodic and anodic electrodes, wherein nitrates are reduced to gaseous products at the cathodic electrode and wherein hydrogen, oxygen and chlorine are not produced. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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Specification