A water-softening system includes a filter device including filter units that are provided in at least some of a plurality of supply channels arranged in parallel to supply raw water to a consumption site and that remove at least part of ionic matter contained in supplied raw water by electro-deionization and discharge soft water containing less ionic matter than the raw water, a plurality of supply valves provided in the plurality of supply channels to open or close the supply channels, and a processor connected to the filter device and the plurality of supply valves. The processor determines whether water is supplied to the consumption site and controls at least one of the plurality of supply valves to remain open to maintain a state in which water is allowed to be supplied to the consumption site, when it is determined that no water is supplied to the consumption site.

An electrolyte solution production device includes: an electrolysis unit that includes a stacked body having conductive film stacked and interposed between electrodes adjacent to each other and is configured to electrolyze a liquid; and housing having the electrolysis unit disposed in an inside of the housing. In addition, housing includes inflow port into which the liquid supplied to the electrolysis unit flows and outlet port from which an electrolyte solution produced in the electrolysis unit flows out. Conductive film has protrusion that protrudes toward the inner surface of housing and is provided to position conductive film with respect to housing. This can provide the electrolyte solution production device in which conductive film can be downsized and easily positioned with respect to housing.

Perfluorinated and polyfluorinated compounds in an effluent stream are destroyed by means of electro-oxidation. Although electro-oxidation can be used to directly treat effluent, a more efficient use is to pre-concentrate applicable pollutants with filters or sorbents. Concentrated perfluorinated and polyfluorinated compounds are removed from the filter or sorbent with a regenerant solution and treated by electro-oxidation. A current density of 0.5 mA/cm.sup.2 or 1 mA/cm.sup.2 effectively reduces the level of perfluorinated contaminants within 1-3 hr. using a titanium electrode. This allows both the regenerant and filter or sorbent to be reused and greatly reduces the amount of material that must be treated as hazardous waste.

A carbon fiber filter includes a center filter body and carbon fiber yarn wound around the center filter body. The center filter body is hollow and includes a water outlet. A surface of the center filter body is provided with at least one inverted triangular groove. A plurality of through holes are arranged in the groove. The through holes and the water outlet are in communication with a hollow inner cavity of the center filter body. The carbon fiber yarn is wound in the groove with a constant force to form a filter layer.

An electrolysis system for water cleaning employs close anode and cathode plate spacing while providing cleaning of the plates. In one embodiment a moving anode allows access to the plates for cleaning.

This disclosure provides techniques for treatment of aqueous matrices using electrolysis to produce soluble metals. An aqueous matrix of interest is passed through an electrolysis device with at least one consumable electrode, which dissolves under applied current, transferring a desired reagent to the aqueous matrix of interest. In one embodiment, the electrolysis device is used in a water delivery network to passivate hexavalent chromium (Cr6) and/or convert it to trivalent chromium; the electrode can be made of food-grade metal tin, which is electrolyzed to form a stannous reagent, which then reacts with the Cr6. The disclosed techniques provide for Cr6 passivation without requiring the use of concentrated acids or other harmful substances. Long term reagent generation efficiency can be enhanced through the use of cleaning processes which maintain a fresh electrode surface in contact with the aqueous matrix of interest.

Perfluorinated and polyfluorinated compounds in an effluent stream are destroyed by means of electro-oxidation. Although electro-oxidation can be used to directly treat effluent, a more efficient use is to pre-concentrate applicable pollutants with filters or sorbents. Concentrated perfluorinated and polyfluorinated compounds are removed from the filter or sorbent with a regenerant solution and treated by electro-oxidation. A current density of 0.5 mA/cm.sup.2 or 1 mA/cm.sup.2 effectively reduces the level of perfluorinated contaminants within 1-3 hr. using a titanium electrode. This allows both the regenerant and filter or sorbent to be reused and greatly reduces the amount of material that must be treated as hazardous waste.

Self-cleaning electrochemical cells, systems including self-cleaning electrochemical cells, and methods of operating self-cleaning electrochemical cells are disclosed. The self-cleaning electrochemical cell can include a plurality of concentric electrodes disposed in a housing, a fluid channel defined between the concentric electrodes, and an electrical connector positioned at a distal end of a concentric electrode and electrically connected to the electrode. The electrical connectors may be configured to provide a substantially even current distribution to the concentric electrode and minimize a zone of reduced velocity occurring downstream from the electrical connector. The electrical connector may be configured to cause a temperature of an electrolyte solution to increase by less than about 0.5° C. while transmitting at least 100 W of power.

Provided are a system for treating wastewater and a cleaning method thereof. The wastewater treatment system includes: a wastewater compartment, a first electrode, a second electrode, an acid compartment, a base compartment, an acid supply apparatus, a base supply apparatus, a control apparatus, and a power supply device. During the cleaning process, the power supply device provides reverse potential to the first and the second electrodes. The control apparatus shut off a first channel so that the acid supply apparatus provides an acid solution to the base compartment through a second channel, and shut off a third channel so that the base supply apparatus provides an alkaline solution to the acid compartment through a fourth channel, without shutting off the wastewater treatment system.

Disclosed is a water treatment device such as a water purifier. In particular, a water treatment device capable of producing sterilizing water is disclosed. The device includes a sterilizing water producing module for electrolyzing raw water to produce sterilizing water, wherein the sterilizing water producing module includes a plurality of first electrodes and a plurality of second electrodes arranged alternately with each other and spaced from each other, wherein the first and second electrodes have opposite polarities to each other, wherein a polarity of each of the first electrode and the second electrode is switchable to between a positive potential and a negative potential, such that the sterilizing water producing module operates such that a positive potential operation and a negative potential operation are alternately repeated, wherein a magnitude of voltage or current applied to the sterilizing water producing module under the negative potential operation is smaller than a magnitude of voltage or current applied to the module under the positive potential operation.