Abstract: The present invention relates to a method for isolation of ionic species from a liquid and an apparatus for isolation of ionic species from a liquid. Moreover the invention relates to an electro enhanced dialysis cell and the use of the cell in the method and the apparatus.

Abstract: In the deionization apparatus, among a pair of electrode modules to which a power is applied, only one electrode module includes an electrode capable of adsorbing ions to impart an ion-adsorption capability thereto and the other electrode module includes an electrode having no ion-adsorption capability not to impart an ion-adsorption capability thereto, to remove only one of cations and anions, in order to improve production efficiency and reduce manufacturing costs.

Abstract: In regenerating an electroless metal plating bath by electrodialysis, it has been found that the metal of the metal plating bath deposits in the electrolysis arrangement. To overcome this problem, an improvement to prior art regenerating devices is suggested, said improvement consisting in providing main cation exchangers for removing ions of this metal from a concentrate fluid. The main cation exchangers are coupled to the concentrate compartments of the electrolysis arrangement in such a manner that the concentrate fluid flowing through the concentrate compartments is allowed to pass through the main cation exchangers and to be recirculated back into the concentrate compartments.

Abstract: An efficient system for desalinization of water is described wherein multiple stages of deionization result in drinking water quality and provision is made for recycling wastewater through the system.

Abstract: Methods and compositions for electrolessly depositing Co, Ni, or alloys thereof onto a substrate in manufacture of microelectronic devices. Grain refiners, levelers, oxygen scavengers, and stabilizers for electroless Co and Ni deposition solutions.

Abstract: Methods and compositions for electrolessly depositing Co, Ni, or alloys thereof onto a substrate in manufacture of microelectronic devices. Grain refiners, levelers, oxygen scavengers, and stabilizers for electroless Co and Ni deposition solutions.

Abstract: The present invention is directed to a water treatment or purification system and method for providing treated water in industrial, commercial and residential applications. The treatment system provides treated or softened water to a point of use by removing at least a portion of any hardness-causing species contained in water from a water source, such as municipal water, well water, brackish water and water containing foulants. The water treatment system includes an electrochemical device, such as an electrodeionization device, that can have at least one compartment that generates and traps hydrogen ions which can be used in another compartment of the electrochemical device such as, an electrode compartment, to reduce or at least dissolve any scale. Other applications of the system would be in the treatment and processing of foods and beverages, sugars, various industries such as the chemical, pharmaceutical, waste water treatment and power generating industries.

Abstract: The present invention generally relates to devices able to purify fluids electrically that are contained within pressure vessels, as well as to methods of manufacture and use thereof. Liquids or other fluids to be purified enter the purification device and, under the influence of an electric field, are treated to produce an ion-depleted liquid. Species from the entering liquids are collected to produce an ion-concentrated liquid. Increasing the exterior pressure on the device may reduce the pressure difference between the interior of the device and the exterior, which may reduce manufacturing costs or simplify construction.

Abstract: Methods and compositions for electrolessly depositing Co, Ni, or alloys thereof onto a substrate in manufacture of microelectronic devices. Grain refiners, levelers, oxygen scavengers, and stabilizers for electroless Co and Ni deposition solutions.

Abstract: A liquid treatment process is described for sequential removal of ionic species of progressively decreasing ionic strength without precipitation or “scaling.” An aspect of the invention includes two or more electrodeionization operations within one or more electrodeionization stacks. The first electrodeionization operation is performed at a voltage calculated to remove strongly ionized species such as calcium and magnesium from the feed water without scaling. The product of the first electrodeionization operation is then subjected to a second electrodeionization operation. The second electrodeionization operation is performed at a voltage the same as the first electrodeionization operation, and is designed to remove more weakly ionized species such as silica and carbon dioxide, preventing scaling. More than two successive electrodeionization operations may be performed if desired. Multiple electrodeionization operations may occur in a single electrodeionization stack or in multiple electrodeionization stacks.

Abstract: A method and apparatus for connecting water treatment devices is provided. Connecting brackets may allow for a multiple configurations of water treatment devices and can simplify the building of water treatment systems.

Abstract: A process is intended to allow simple and particularly reliable electrolyte generation and conditioning from metal-containing used electrolytes and/or used process solutions and/or pulverulent metal wastes. For this purpose, waste products containing metal ions from metal surface treatment processes are to be treated by producing and/or using a metal ion mixed solution, replacing anions contained in the metal ion mixed solution with anions selected for an intended use selected and selectively removing metal ions which are categorized as unsuitable for the intended use selected from the metal ion mixed solution prepared in this way.

Abstract: A fuel cell power plant comprises a water circulation passage (5) which circulates the cooling water in a fuel cell stack (4). Sodium hydroxide which lowers the melting point of water is mixed with water in the water circulation passage (5) to prevent freezing of the water in the water circulation passage (5). Electrodes (11, 12) are disposed in the water. When the fuel cell stack (4) is running, a voltage is applied between the electrodes (11, 12) such that the positive electrode (11) attracts sodium ions, thereby removing sodium ions from the cooling water supplied to the fuel cell stack (4). When the fuel cell stack (4) stops running, sodium ions which were attracted to the positive electrode (11) are made to diffuse into the cooling water by ceasing to apply the voltage to the electrodes (11, 12).

Abstract: A releaseable membrane structure for producing a free membrane containing a substrate, a release stratum on the substrate and a membrane stratum on the release stratum. The release stratum and the membrane stratum contain oppositely-charged polyelectrolytes that are associated. The oppositely-charged polyelectrolytes of the release stratum are selected to dissociate upon application of stimulus whereas those of the membrane stratum are selected to remain associated upon application of the stimulus. Thus, when the stimulus is applied the polyelectrolytes in release stratum dissociate and the membrane stratum is released from the substrate and is a free membrane.

Abstract: In the electrodeionization deionized water producing apparatus, water is passed through a deionizing chamber(s) packed with an organic porous ion exchange material having a three-dimensional network structure to remove ionic impurities in the water, thereby producing deionized water. At the same time, a DC electric field is applied to the deionizing chamber(s) to discharge ionic impurities adsorbed on the organic porous ion exchange material outside the system, wherein the DC electric field is applied so that the ions to be discharged may electrophoretically move in the direction reverse to the flow of water through the organic porous ion exchange material.

Abstract: The dilute support frame is made up of interphase longitude and latitude bars that preferably are hollow. The bars can be rectangular, rectangular with a rounded end, half-circular, triangular, polygonal or any combination thereof. The bars are sized to support the ion exchange resin in the dilute channel adjacent the concentrate membrane bag. The support frame also assures fluent water flow in the dilute channel. The support frames are arrayed on the membranes with interphase aisle to save the frame arrays and make water flow fluently. The membrane envelopes in turn with the support frames as both are preferably wound to form the cylinder module, and is covered by one plastic protecting net. This new type of support frame can assure fluent water flow in dilute channels and convenient resin filling.

Abstract: The resin seepage-proof spiral would Electrodeionization (EDI) module includes anion and cation ion exchange membranes, concentrate and dilute distributing channels, net sheets inside of the channels, positive and negative electrodes and an EDI housing. The housing includes an insulation shell and covers. The multiple layers of anion and cation ion exchange membranes concentrate and dilute water distributing channels and net sheets are wound around a negative electrode pipe centered in the EDI module. The negative electrode pipe is arranged to collect concentrate water inside of the pipe. A circularity positive electrode is located outside the wound membranes and within the insulation shell, which is generally cylindrical in shape. Inside the cylindrical housing, the dilute water distributing channel is filled by ion exchange resin. The EDI module includes two inserts of multiple holed material layer, one on each end of the module.

Abstract: Apparatus and method are disclosed for introducing ion exchange or other particulates into compartments of an already-assembled electrodeionization or comparable stack by modulating a flow of slurry into the compartments with slugs of gas such as air. The air propels liquid through the cells, scavenging ponded liquid so that the particulates (which are retained, e.g., by a strainer or obstruction, in compartment of the apparatus) are deposited as well-packed beds to fill the compartments. Pressurized air filling protocols may deliver discrete slugs of slurry between bursts of air, and the direction of filling may be periodically reversed to diminish particle bed non-homogeneities or settling gradients that arise during transport. The slugs of air may be applied in the direction of slurry flow, in the reverse direction, or both. Different slurries may be transported in a sequence to form layered and packed beds of enhanced utility.

Abstract: The electrodeionization water producing apparatus comprising a depletion chamber packed with an ion exchange material, the depletion chamber being partitioned by a cation exchange membrane on one side and an anion exchange membrane on the other side, and concentrate chambers installed on both sides of the depletion chamber with the cation exchange membrane and the anion exchange membrane disposed inbetween, the depletion chamber and the concentrate chambers disposing between an anode chamber equipped with an anode and a cathode chamber equipped with a cathode, wherein the concentrate chambers are packed with an organic porous ion exchange material having a continuous pore structure in which the wall made from interconnected macropores contains mesopores with an average diameter of 1 to 1,000 ?m. The apparatus ensures reduction of electric resistance and does not form scale in the concentrate chamber during long continuous operation.

Abstract: An EDI device includes a composite electrode enclosed within the cylinder shell of the device. The EDI inner module preferably has one concentrate center pipe as the electrode in the center axis and at least one layer of anion/cation exchange membranes and a support frame in concentrate/dilute chambers wound around the center pipe. The electrode plate is inside the encircled cylindrical shell (isolating vessel). It is connected to an electrical contact plate located in the shell. Either the anode or cathode can be set in the center pipe, and the other electrode can be set in the vessel or shell lining. The electrical contact plate also contacts an electrical contact reed located on the vessel cover when the cover is connected to the shell. The electrical contact plate provides a reliable conductive bridge between the contact reed and the electrode plate and thus passes DC from the contact reed to the electrode plate.

Abstract: The present invention provides a method and apparatus for purifying effluent wastewater utilizing electrophoretic cross-flow filtration and electrodeionization. The method first comprises filtering the water in a cross-flow direction with a filter membrane (120) in the presence of an electric field that is operative to drive suspended particles away from a surface of the filter membrane (120). The permeate (134) containing dissolved solids is next passed through a mixture (188) of at least one cation-exchange resin and at least one anion-exchange resin disposed between a cation-selective membrane (184) and an anion-selective membrane (181) in the presence of an electric field. The electric field drives cations in the permeate through the cation-selective membrane (184), and drives anions in the permeate through the anion-selective membrane (181), thereby to form deionized water (192). The apparatus includes cell modules adapted to be used in plate-and-frame or radial flow configurations.

Abstract: In a device for electro-deionization (EDI) in the demineralization of aqueous solutions, which device includes ion exchange membranes arranged alternately and in spaced relationship so that between the membranes compartments are formed of which at least some are filled with cation and anion resin exchange particle fractions forming a mixed bed ion exchanger, the ion exchange resin particles of one of the two fractions include a magnetic material and a magnetic field generator is provided for generating a field for orienting the magnetic resin particles and arranging them in parallel chains extending between the membranes.

Abstract: An apparatus for removing charged contaminants from a water stream. The apparatus can be figured to provide the decontaminated water stream to an analytical system. Methods of use of the same are also disclosed.

Abstract: The resin seepage-proof spiral would Electrodeionization (EDI) module includes anion and cation ion exchange membranes, concentrate and dilute distributing channels, net sheets inside of the channels, positive and negative electrodes and an EDI housing. The housing includes an insulation shell and covers. The multiple layers of anion and cation ion exchange membranes concentrate and dilute water distributing channels and net sheets are wound around a negative electrode pipe centered in the EDI module. The negative electrode pipe is arranged to collect concentrate water inside of the pipe. A circularity positive electrode is located outside the wound membranes and within the insulation shell, which is generally cylindrical in shape. Inside the cylindrical housing, the dilute water distributing channel is filled by ion exchange resin. The EDI module includes two inserts of multiple holed material layer, one on each end of the module.

Abstract: An apparatus for the electrodialytic regeneration of an electroless bath electrolyte. There are diluate compartments through which the bath electrolyte is channeled, concentrate compartments through which a regeneration electrolyte is channeled, an anode, and a cathode. The diluate compartments of the first electrodialysis unit are serially connected to the diluate compartments of the second electrodialysis unit via lines through which the bath electrolyte is sequentially channeled. The concentrate compartments of the first electrodialysis unit are serially connected to the concentrate compartments of the second electrodialysis unit via lines through which the regeneration electrolyte is sequentially channeled.

Abstract: An electrodeionization apparatus and method for purifying a fluid. A fluid, such as water, can be purified by removing weakly ionizable species from the fluid. Weakly ionizable species may be dissociated at different pH levels to facilitate removal from the fluid in an electrodeionization device.

Abstract: A bipolar membrane which exhibits a low water dissociation voltage for an extended period of time under a high current density condition, and a high current efficiency, without developing blister. The bipolar membrane comprises a cation-exchange membrane and an anion-exchange membrane which are joined together, wherein ion-exchange resin particles having ions exchanged with ions of a metal of an atomic number 20 to 90, such as titanium, zirconium, tin, iron, ruthenium or palladium, or with complex ions of said metal are existing on the junction interface between the cation-exchange membrane and the anion-exchange membrane.

Abstract: Electrodeionization apparatus and method. The electrodeionization apparatus includes an ion-depleting compartment in which alternating layers of an electroactive media are positioned. One of the alternating layers is doped to provide a more balanced current distribution through the apparatus. The method involves providing reducing the difference in conductivity between the alternating layers positioned in the ion-depleting compartment by adding a dopant material to one of the layers.

Abstract: A porous immobilized ion-exchange material is provided. Also provided is an electrodeionization device incorporating the material. A method for subjecting a fluid to electrodeionization, is provided utilizing porous immobilized ion-exchange material. A salient feature of the material is that it can be regenerated in situ.

Abstract: An electrodeionization (EDI) module is formed an anode spaced apart from a cathode, one or more waste channels formed between the electrodes and a product channel located inward of the waste channel(s). Ion permeable membranes form the boundary between the product channel and the waste channel(s). The product channel and waste channels are filled with a mixture of anionic and cationic ion exchange materials. At least the waste channel(s) and preferably the product channel as well, use either an anion bead having a relatively low affinity for the selected anion specie(s) to be retained (e.g. Type II) or it is a blend with Type I materials. Preferably, the membranes contain an ion exchange material to speed the transfer of ions across them. More preferably, the anionic membrane contains anion materials that have a relatively low affinity for the selected specie or species for retention.

Abstract: The invention relates to a composite or a composite membrane consisting of an ionomer and of an inorganic optionally functionalized phyllosilicate. The isomer can be: (a) a cation exchange polymer; (b) an anion exchange polymer; (c) a polymer containing both anion exchanger groupings as well as cation exchanger groupings on the polymer chain; or (d) a blend consisting of (a) and (b), whereby the mixture ratio can range from 100% (a) to 100% (b). The blend can be ionically and even covalently cross-linked. The inorganic constituents can be selected from the group consisting of phyllosilicates or tectosilicates.

Abstract: An electrodialysis apparatus and method for purifying water. An electrodialysis apparatus including an anode and anode chamber, a cathode and cathode chamber, and a desalting stream flow path comprising a first portion juxtaposed to the anode and a second portion juxtaposed to the cathode is described. By passing water through the apparatus, purified water is produced.

Abstract: A method and a device for the regeneration of an electroless metal deposition bath containing hypophosphite ions by electrodialysis is described. The method according to the invention and the device differ from the prior art in that the bath solution is led simultaneously through diluate compartments in a second electrodialysis unit having cathodes and anodes, which compartments are separated from concentrate compartments in the second electrodialysis unit on the cathode side by monoselective anion-exchange membranes and on the anode side by anion-exchange membranes, the diluate compartments and the concentrate compartments in the second electrodialysis unit being disposed alternately to one another.

Abstract: Bipolar membrane electrodialysis methods for salt splitting polyvalent metal salts, where the metal cation can form substantially insoluble precipitates in the presence of hydroxyl ions can now be used in recovering acid and base values from a salt streams without precipitates fouling cell operation and causing shutdown. The introduction of an acid to the chamber where metal hydroxides would form inhibits their development or neutralizes formed solids, allowing salt splitting to continue. Salt splitting methods of the invention performed with a three compartment bipolar electrodialysis cell are useful in producing concentrated and purified acid forms, such as 2-keto-L-gluconic acid, H(KLG), a key intermediate in the production of ascorbic acid.

Abstract: An apparatus and process produces salts by an electrodialysis operation. The basic electrodialysis apparatus is a cell having a number of compartments separated by membranes. A DC source is connected to drive a current through a feed stream passing through the cell which splits the salt stream into an acid and a base. The incoming feed may be nanofiltered to remove divalent metal. The base loop may be in communication with an ion exchange column packed with a material that removes multivalent cations. Depending upon the material being processed and the desired end result either or both the nanofiltration and the ion exchanged column may be used in the apparatus.

Abstract: A device for producing ion water comprises an electrolytic cell which can be electrolyzed; two ion exchange units which are disposed ion exchange membrane such that the electrolytic cell is partitioned in three electrolytic chambers therein respectively; an anode electrode which is provided in an intermediate electrolytic chamber of the electrolytic cell; and a cathode electrode which is provided in the electrolytic chambers located on both sides of the electrolytic cell respectively, the cathode electrode being flowed half amount of an electric current which is flown to the anode electrode therein respectively, so that the desired pH of the ion can be controlled because the generative quantity of hydrogenous ion can be balanced by controlling the quantity of electricity of turning on electricity.

Abstract: An electrodialytic method and device for the simultaneous production of acids and bases of high purity and higher concentration operates by splitting corresponding salts in aqueous solution using an electrolysis cell. The electrolysis cell includes a cathode chamber in which an alkali is formed, a salt chamber for supplying a salt to be split, an acid chamber in which the acid is formed, and an anode chamber through which a mineral acid flows as a proton carrier. The anode is a hydrogen-consuming electrode. The method and device are preferably used in the production of hydrochloric acid and sodium hydroxide solution.

Abstract: A device for producing ion water having a pleasant odor, comprising an electrolytic cell containing two partition walls equipped with ion exchange membranes such that the cell is partitioned into three electrolytic chambers therein, said device also provided with spicery-supplying means such that ion water is produced inside at least one electrolytic chamber. In addition, an anode is located in the intermediate electrolytic chamber, and cathodes are located in the electrolytic chambers at both sides in the electrolytic cell respectively. Therefore, the desired pH of the ion water having a pleasant odor can be achieved by controlling the quantity of hydrogen ions generated as determined by the amount of electricity delivered.

Abstract: Electrodeionization apparatus for purifying water includes a cathode, an anode, and a plurality of alternating anion permeable membranes and cation permeable membranes between the cathode and anode that define concentrating and diluting flow channels between adjacent pairs of membranes. Each concentrating flow channel includes a first guard channel adjacent to the anion permeable membrane, a second guard channel adjacent to the cation permeable membrane, and a brine channel between the first and second guard channels. The first and second guard channels have water with lower concentration of dissolved ions than water in the brine channel so as limit parasitic transfer from a concentrating flow channel to a diluting flow channel.

Abstract: A water-processing domestic appliance with means (410; 620) for processing water and, upstream of said means, a cathode (35) and an anode (45) for the de-ionization of water in a de-ionization space (50) before said water is processed. A cathode screen (31) screens off a cathode region (30) from the de-ionization space (50), said cathode (35) being situated in the cathode region (30), while at least a portion of the cathode screen (31) is formed by a kation membrane (32). A much reduced maintenance necessity is achieved in that ions can be removed from the water to be processed without necessarily depositing on the cathode, and can be removed from the cathode region together with liquid.

Abstract: Electrodeionization packing including one or more macrostructural elements made up of smaller, microstructural elements. The microstructural elements are in fixed, close contacting position with respect to each other in the macrostructural elements so as to provide porosity in the macrostructural elements. A majority of the microstructural elements have a characteristic dimension between 10 and 50 micrometers, and the macrostructural elements have a void fraction between about 25% and 50%.

Abstract: Electrodeionization apparatus for purifying water that includes a cathode, an anode, and a plurality of alternating anion permeable membranes and cation permeable membranes between the cathode and anode that define concentrating and diluting flow channels between adjacent pairs of membranes. The diluting channels include cation exchange materials and anion exchange materials that are fixed in close contacting position with respect to each other and provide conductive paths for cations and anions to the adjacent membranes and provide flow passages for water between the materials. The anion exchange materials and cation exchange materials each have a characteristic dimension that is smaller than the characteristic dimensions of the flow passages.

Abstract: A bipolar membrane, usable for electrodialysis of aqueous electrolytes, comprises two ion exchange membranes, respectively anionic and cationic, juxtaposed along a common surface, wherein, along said common surface, a gel based on hydrated metal sulpate and/or sulphite, including less than 0.01 mol % of indium, cerium, manganese and copper sulphates gel, is formed.

Abstract: A modular sysTem for the demineralization of aqueous liquids comprising a plurality of modular units, each of the modular units being encapsulated and having a cathode proximate a first end of the modular unit and an anode proximate the opposite end of said modular, a plurality of alternating diluting compartments and concentrating compartments positioned between the cathode and the anode, and ion exchange material positioned within the diluting compartments. Each of the diluting compartments has a compartment spacer with an elongated central cavity and a plurality of fine slit openings at each end adjacent the cavity. The ion exchange means comprise a porous and permeable continuous phase of cation or anion exchange resin particles and a porous and permeable dispersed phase of clusters of the other of the cation or anion exchange resin particles.

Abstract: A helical electrodeionization apparatus is adapted to purify aqueous liquids to effect the production of high purity water. An insulated net-separating wall is positioned between a pair of anion and cation exchange membranes to form a special membrane bag type flow unit I, each flow unit I is linked up with a group of slots on the side walls of central pipe, and is rolled up to form cylinder structure which centers on central pipe as the helical axis, a conductive crust is formed by winding metal strip or wire outside the cylinder. Ion exchange resin is filled up between the adjacent membrane bags to form flow unit II. The present invention has less pressure drop and needs less power, and is suited to multiple-device series operation. Preferably, daily maintenance and renewal of the resin is convenient, and production cost is lower.

Abstract: First and second stages are used in electrodeionization to purify water including calcium and carbon dioxide and its hydrates. The diluting flow channels of the first stage include only anion exchange material or cation exchange material, and thus remove either carbon dioxide and its hydrates (and other anions) or calcium (and other cations) but not the other. The diluting flow channels of the second stage receive the diluting channel effluent from the first stage and include the other type of exchange resin (or a mixed resin) and remove the oppositely charged ions. The brine effluent from the concentrating flow channels in the first stage is isolated from the second stage, and calcium and total inorganic carbon tend to be removed in different stages so as to deter calcium carbonate precipitation in any of the concentrating flow channels.

Abstract: The invention relates to a method and a device for regenerating exhausted tin-plating solutions which contain tin and copper ions, free complexing agent and complexing agent bound to the copper ions, as well as expended and unexpended reducing agent. By means of a suitable rinsing technique, the rinse water of the tin-plating process is concentrated to a 10 to 15 percent dilution of the process solution. The regenerating solution thus produced is fed to an electrolytic cell. The electrolytic cell comprises a cathode chamber, a middle chamber and an anode chamber. The cathode chamber is separated from the middle chamber by an anion-exchange membrane and the anode chamber is separated from the middle chamber by a cation-exchange membrane. The regenerating solution is initially provided in the cathode chamber. Here, the interfering copper component is cathodically deposited.

Abstract: An integral, monolithic frame-membrane is disclosed, such frame-membrane having a semi-permeable membrane portion and integral therewith a frame portion, the frame portion having one or more cavities, each cavity juxtaposed to the membrane portion, each cavity having at least one fluid entrance conduit communicating with an entrance manifold aperture and at least one fluid exit conduit communicating with an exit manifold aperture. The integral, monolithic frame-membrane may be used in apparatus for carrying out gas-separation; microfiltration; ultrafiltration; nanofiltration; reverse osmosis (i.e. hyperfiltration); diffusion dialysis; Donnan dialysis; electrodialysis (including filled-cell electrodialysis; i.e. electrodeionization); pervaporation; piezodialysis; membrane distillation; osmosis; thermo osmosis; and electrolysis with membranes.

Abstract: Sweet whey is demineralized by an electrodeionization process by passing sweet whey to be demineralized through a resin bed of strong cationic exchange resin contained in an electrodeionization dilution compartment or through a resin bed of weak anionic and of cationic, particularly strong cationic, exchange resins in the compartment, and in the process, the pH of the wash solution present in the electrodionization cation and anion concentration compartments is maintained so that the solution present in each concentration compartment has a pH value less than 5.

Abstract: A helical electrodeionization apparatus is adapted to purify aqueous liquids to effect the production of high purity water. An insulated net-separating wall is positioned between a pair of anion and cation exchange membranes to form a special membrane bag type flow unit I, each flow unit I is linked up with a group of slots on the side walls of central pipe, and is rolled up to form cylinder structure which centers on central pipe as the helical axis, a conductive crust is formed by winding metal strip or wire outside the cylinder. Ion exchange resin is filled up between the adjacent membrane bags to form flow unit II. The present invention has less pressure drop and needs less power, and is suited to multiple-device series operation. Preferably, daily maintenance and renewal of the resin is convenient, and production cost is lower.