Abstract: In a capacitive deionization water desalination apparatus, the waterways of the cell are physically switchable between treatment-phase and purge-phase. In treatment-phase, the waterways conduct the flow of water thickness-wise, in-series, through the whole stack of electrodes and spacers. In purge-phase, the waterways conduct the flow of purge-water into the edges of the spacers, and along the spacers parallel to the plane of the spacers.

Abstract: A water treatment apparatus comprising a stack of circular electrodes with a central through hole, the electrodes are supplied with electricity so as to form anodes and cathodes in alternating intercalation. The anodes and cathodes so arranged to lie in such close-spaced parallel face to face relationship as to form a capacitive deionization cell. Water to be treated is passed from the outside of the stack, radially inward through between the electrodes into the central through hole and then axially out of the stack.

Abstract: In a capacitive deionization water desalination apparatus, the waterways of the cell are physically switchable between treatment-phase and purge-phase. In treatment-phase, the waterways conduct the flow of water thickness-wise, in-series, through the whole stack of electrodes and spacers. In purge-phase, the waterways conduct the flow of purge-water into the edges of the spacers, and along the spacers parallel to the plane of the spacers.

Abstract: The softener is based on a capacitive-deionization (CDI) cell, in which the hardness ions are extracted, and disposed of still intact, in concentrated form. The softener is combined with a chelate to inhibit precipitation, in the appliance, from the concentrated effluent. The chelate being citric acid, the acidity is effective to keep the hardness ions in solution. The purify and regenerate modes of operation of the softener can be timed to coincide with the washing and rinsing cycles of the appliance, whereby the presence of the softener does not affect the speed and performance of the appliance.

Abstract: The capacitive electrodes of the CDI cell are arranged to form a tube. Water to be treated flows through the tube-walls. The CDI electrodes are permeable, and form the tube-walls, whereby the flow passes through the thicknesses of the electrodes and of the spacers. The electrodes may be in the form of concentric tubes, or may be wrapped spirally.

Abstract: Nickel entrained in the sulphide mineral pyrrhotite is engineered to dissolve in leaching acid in a two step procedure. First, a slurry of the mineral and the acid is activated by oxidation. This is done in a time T1 by electrolysis; or alternatively chemically, by adding e.g an oxidizing acid to the mineral. After activation, the slurry is then kept under anoxic conditions for a time T2. During T2, the sulphide starts to dissolve much more rapidly, and the rapid breakdown of the sulphide enables the nickel to dissolve and thus to be leached out of the mineral. The dissolved nickel is extracted from the leaching acid e.g by electro-winning.

Abstract: The electrodes of the described CDI cell are porous and permeable. The liquid to be deionized (e.g. salt water to be desalinated) flows through the electrodes. The electrodes are arranged in a stack, alternating anode/cathode, and water being treated passes through every electrode in the whole stack. For regeneration, the cells are connected (short-circuited) together, and the ions are dislodged mainly by flushing action. The through-flow arrangement can be realized in a number of different configurations.

Abstract: A water treatment apparatus comprising a stack of circular electrodes with a central through hole, the electrodes are supplied with electricity so as to form anodes and cathodes in alternating intercalation. The anodes and cathodes so arranged to lie in such close-spaced parallel face to face relationship as to form a capacitive deionization cell. Water to be treated is passed from the outside of the stack, radially inward through between the electrodes into the central through hole and then axially out of the stack.

Abstract: Nickel entrained in the sulphide mineral pyrrhotite is engineered to dissolve in leaching acid in a two step procedure. First, a slurry of the mineral and the acid is activated by oxidation. This is done in a time T1 by electrolysis; or alternatively chemically, by adding e.g an oxidizing acid to the mineral. After activation, the slurry is then kept under anoxic conditions for a time T2. During T2, the sulphide starts to dissolve much more rapidly, and the rapid breakdown of the sulphide enables the nickel to dissolve and thus to be leached out of the mineral. The dissolved nickel is extracted from the leaching acid e.g by electro-winning.

Abstract: In a sewage treatment plant, dissolved ammonium is extracted from the waste-water stream, and is transferred to a body of secondary water. The secondary water is passed through an electrolysis station, where the ammonium is transformed to nitrogen gas. The capture and transfer can be done by ion-exchange, the electrolysis then being done on the regenerant water. Or the capture and transfer can be done by first transforming the dissolved ammonium to ammonia gas by raising the pH of the waste-water, then passing the ammonia gas through acidic secondary-water, in which the ammonia dissolves, the electrolysis then being done on the acid-water. The electrolysed, ammonium-diminished, secondary-water can be re-used in further capture/transfer episodes. The secondary-water does not mix with the waste-water stream.

Abstract: Acidity in water leaching from a mass of sulphide tailings is prevented by de-oxygenating the water prior to entering the mass. A cover comprising an electrolytic cell, either galvanic or impressed-current, gives rise to a cathode reaction in which the redox voltage of the water drops to 003 volts or less. The cover can be thinner, and much less expensive, than an equally-effective non-reactive cover. The electrolyte is water contained in water-retaining soil, or a depth of water, lying over the cathode. The cathode is steel mesh, or a layer of graphite, spread over the whole mass of tailings.

Abstract: For alleviating acid mine drainage arising from oxygenated water passing through pyrite, the water is de-oxygenated in an intercepting protective layer, which comprises a mixture of grains of pyrite and grains of iron. The grain sizes, concentrations, etc are selected to create an ensemble of galvanic cells at the points of contact between the iron grains and the pyrite grains. The pyrite cathode material becomes cathode-protected, and the water becomes de-oxygenated, by the electrolytic action.

Abstract: Copper is extracted from a heap of low-grade ore by transforming the heap into an electrolytic cell, and imposing a voltage thereon. Anodic conditions of redox and pH cause the sulphide to break down, and the copper to pass into solution. The copper can be recovered elsewhere if the electrolyte is drawn off, or in-situ if allowed to plate onto the cathode. Electrodes are formed as grids of conductors, or as layers of e.g. graphite.

Abstract: Waters contaminated by nitrogenous compounds such as nitrate, ammonium, etc., are treated by electrochemical transformation of the contaminant to nitrogen gas. Electrodes are placed in the contaminated water to form a cell, in which the voltage of one of the electrodes is set to the Eh voltage at which nitrogen gas is thermodynamically favored. The cell may be electrolytic or galvanic.

Abstract: Treatment is described for acidity caused by water seeping down through a seam of acid-generating mineral such as pyrite. The pyrite oxidises through exposure to the atmosphere (as a result of mine workings). The treatment system creates an galvanic cell, using the submerged portion of the pyrite seam as the cathode, the water in the aquifer as the electrolyte, and a body of scrap iron immersed in the water as the (sacrificial) anode. Contact rods are inserted into the pyrite seam, and are connected, via a cable, to the body of scrap iron, which is placed in a nearby pond. Hydrogen ions migrate to the cathode and bubble off as hydrogen gas, raising the pH. The acid generating reactions in the pyrite seam are inhibited, and acid concentrations in the already contaminated water in the pond and in the aquifer are reduced. In an alternative, the exposed beaches of pyrite in a tailings pond are provided with grids of metal mesh or graphite in place of the inserted rods.