Method and apparatus for removing nitrates from water

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.