WO2020077918A1 - Système de recyclage de saumure à base de membrane bipolaire - Google Patents

Système de recyclage de saumure à base de membrane bipolaire Download PDF

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Publication number
WO2020077918A1
WO2020077918A1 PCT/CN2019/073405 CN2019073405W WO2020077918A1 WO 2020077918 A1 WO2020077918 A1 WO 2020077918A1 CN 2019073405 W CN2019073405 W CN 2019073405W WO 2020077918 A1 WO2020077918 A1 WO 2020077918A1
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Prior art keywords
compartment
water
electrodialyzer
fluid
bipolar membrane
Prior art date
Application number
PCT/CN2019/073405
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English (en)
Inventor
Qiuhong QUAN
Jianfei Zhang
Xifang YUAN
Qing Zhao
Original Assignee
Bgt Group Co., Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN201811208101.2A external-priority patent/CN109248565B/zh
Priority claimed from CN201811214315.0A external-priority patent/CN109293087B/zh
Priority claimed from CN201811214419.1A external-priority patent/CN109250846B/zh
Application filed by Bgt Group Co., Ltd filed Critical Bgt Group Co., Ltd
Priority to CN201980010383.1A priority Critical patent/CN111954568B/zh
Publication of WO2020077918A1 publication Critical patent/WO2020077918A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
    • B01D65/08—Prevention of membrane fouling or of concentration polarisation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • B01D61/445—Ion-selective electrodialysis with bipolar membranes; Water splitting
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/25—Recirculation, recycling or bypass, e.g. recirculation of concentrate into the feed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2311/00—Details relating to membrane separation process operations and control
    • B01D2311/25—Recirculation, recycling or bypass, e.g. recirculation of concentrate into the feed
    • B01D2311/252—Recirculation of concentrate
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/78—Treatment of water, waste water, or sewage by oxidation with ozone
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/08—Seawater, e.g. for desalination
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00—Apparatus for treatment of water, waste water or sewage
    • C02F2201/46—Apparatus for electrochemical processes
    • C02F2201/461—Electrolysis apparatus
    • C02F2201/46105—Details relating to the electrolytic devices
    • C02F2201/46115—Electrolytic cell with membranes or diaphragms
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/22—Eliminating or preventing deposits, scale removal, scale prevention

Definitions

  • the present invention relates to the technical field of wastewater treatment equipment, and more particularly relates to bipolar-membrane-based brine recycling system.
  • a bipolar membrane is a kind of ion exchange membrane with special functions, in which, under the effect of electric field, water in the intermediate layer is dissociated to generate H + and OH - .
  • Bipolar membrane electrodialysis technology is to integrate this special function into common electrodialysis, thereby realizing real-time production/regeneration of acid/alkali, or acidification and/or alkalization.
  • This technology has already been put into force in inorganic processes, such as producing corresponding acid and alkali from NaCl, Na 2 SO 4 , KF, KNO 3 , (NH 4 ) 2 SO 4 solutions or waste water.
  • Bipolar membrane electrodialysis technology belongs to electrodialysis technology, and in the process of electrolyzing halogen-element-containing water solutions to produce acid or alkali, halogen gases are generated inevitably at the anode.
  • the generated gases dissolve in the water, electrical resistance of the electrolytic solution and the voltage required are significantly increased, leading to increased energy cost. Meanwhile, the generated halogen gases are poisonous, which cannot be discharged directly and require corresponding treatment equipment, resulting in increase of production cost.
  • the electrolytic solution contains halogen elements, the pH of the anode compartment at the anode side would decrease and the pH of the cathode compartment at the cathode side would increase.
  • CN107382737A discloses a preparation method of biquaternary ammonium hydroxide, comprising: electrolyzing biquaternary ammonium salt into biquaternary ammonium ions and corresponding anions by a bipolar membrane electrodialysis process; simultaneously dissociating water via bipolar membranes to generate hydrogen ions and hydroxyl ions; with the permselectivity of ion exchange membranes and under the effect of an external electric field, the biquaternary ammonium ions and the hydroxyl ions reacting so as to produce the biquaternary ammonium hydroxide; hydrogen ions reacting with anions generated through biquaternary ammonium salt electrolysis to produce acid.
  • An intermittent operation i.e. shutting down after desalting one batch and acid cleaning the system, is bound to bring about negative effects such as complicated operation, unstable desalting performance and short working life of the ion exchange membranes.
  • Another regular operation is to adjust the ion concentration of the circling concentrated liquid so as to maintain it at a certain concentration level, thereby reducing the possibility of concentration polarization and scaling.
  • CN101543730 discloses an organic liquid desalinization process and system capable of preventing scale formation, and specifically discloses a system comprising an electrodialyzer, a raw liquid storage tank and a desalting material storage tank, wherein the electrodialyzer comprises an anion-cation exchange membrane alternately arranged between the positive and negative electrodes, the side at the positive electrode is an anode chamber, and the side at the negative electrode is a cathode chamber, and a desalting chamber and a concentrating chamber are alternately formed between the anode chamber and the cathode chamber, and the concentrating chamber and the anode chamber of the electrodialyzer are connected with a softened water tank, and one end of the anode chamber is further connected to the softened water inlet of the concentrating chamber, and the produced water of the desalting chamber is input to the desalting material storage tank.
  • the electrodialyzer comprises an anion-cation exchange membrane alternately arranged between the positive and negative electrodes
  • the side at the positive electrode is an
  • the cathode chamber, the concentrating chamber and the anode chamber are connected to an external softened water tank, and the softened water is supplied to the cathode chamber, the concentrating chamber and the anode chamber, and part of the fluid in the concentration chamber of the electrodialyzer is provided by the concentrated liquid circularly, another part is provided by the softened water tank, which reduces the possibility of scaling, and the structure is simple and easy to operate.
  • a pipe is connected at the outlet of the anode chamber, and the other end of the pipe is connected at the inlet of the concentrating chamber, and the circulating water in the anode chamber is input to the concentration chamber as part of the fluid of the concentration chamber by the pressure inside the electrodialyzer.
  • This invention removes part of the ions from the salted waste water to soften the waste water and reduce the possibility of scaling. But it doesn’t solve the essential problem of the ion exchange membranes themselves, and there still exists great risks of scaling for the ion exchange membranes.
  • the present invention provides a bipolar-membrane-based brine recycling system, at least comprising a bipolar membrane electrodialyzer located downstream a primary electrodialyzer, the system being characterized in that, in a direction of a line connecting an anode and a cathode of the bipolar membrane electrodialyzer, the bipolar membrane electrodialyzer is divided by at least three bipolar membranes into at least a first compartment, a second compartment, and a third compartment, and a fluid entering a first intermediate pool is treated through at least following steps: the fluid being desalinated through a first circling path defined by the primary electrodialyzer and/or a second circling path defined by the primary electrodialyzer and the bipolar membrane electrodialyzer jointly so as to yield a product water; and the fluid circling as electrode liquid in a third circling path defined by the first compartment, an anode compartment of the primary electrodialyzer and the first intermediate pool and a fourth circling path defined
  • the fluid in the first circling path flows in a first direction into a fresh-water compartment of the primary electrodialyzer to be desalinated
  • the fluid in the second circling path flows in a second direction into a concentrated-water compartment of the primary electrodialyzer to be concentrated, in which the first direction and the second direction are such configured that they are parallel and opposite to each other so that a concentration difference between the concentrated-water compartment and the fresh-water compartment is minimal when they are together in a plane perpendicular to the first direction or the second direction.
  • an anion exchange membrane and a cation exchange membrane are provided between two said bipolar membranes so that the bipolar membrane electrodialyzer successively forms, in a direction from its anode to its cathode, the first compartment, the third compartment, a fourth compartment, a fifth compartment, a sixth compartment, and the second compartment, in which the fluid in the second circling path flows successively through the concentrated-water compartment, the third compartment, and the fifth compartment in a third direction to be desalinated and become the product water ; and the product water enters the fourth compartment and the sixth compartment in a fourth direction to be treated and become an acid product and an alkali product, wherein the third direction and the fourth direction are parallel and opposite to each other.
  • the first intermediate pool has therein a pH sensor for monitoring a pH value of the fluid, in which when the fluid in the third circling path and the fourth circling path flows back to the first intermediate pool, if the pH value measured by the pH sensor exceeds a predetermined range, the acid product or the alkali product flows back to the first intermediate pool to adjust the pH value of the fluid.
  • the brine recycling system further comprises a water quality monitor installed in the second intermediate pool, in which the water quality monitor is configured to monitor at least a chloride ion concentration, a heavy metal ion concentration and/or a suspended solid content, and the fluid in the second intermediate pool circles and is treated along the first circling path and/or the second circling path, until an output water indicator of the fluid satisfies a predetermined criterion set for the water quality monitor.
  • a level monitor is installed in the second intermediate pool, in which when the level monitor detects that a liquid level of the fluid in the second intermediate pool is smaller than a first predetermined height, communication between the second intermediate pool and the first intermediate pool is established so that the second intermediate pool is filled with the fluid, and when the level monitor detects that the liquid level of the fluid in the second intermediate pool is greater than a second predetermined height, the communication between the first intermediate pool and the second intermediate pool is removed, wherein when the communication between the first intermediate pool and the second intermediate pool is not established, the fluid in the second intermediate pool circles and is treated along the first circling path and/or the second circling path, until the output water indicator of the fluid satisfies the predetermined criterion set for the water quality monitor.
  • the present invention also provides a brine recycling system with inhibition of scaling, at least comprising a primary electrodialyzer and a bipolar membrane electrodialyzer, wherein the bipolar membrane electrodialyzer is configured into the work mode in which a fluid treated by a first compartment neutralizes the acidic fluid yielded by the treatment of the anode compartment in a third circling path, and the second compartment is configured into the work mode in which the fluid treated by it neutralizes the alkaline fluid yielded by the treatment of the cathode compartment in a fourth circling path; and the primary electrodialyzer is such configured that the fluid enters a concentrated-water compartment and a fresh-water compartment in parts between which a pressure difference exists, respectively, in which anion exchange membranes and/or cation exchange membranes between adjacent said concentrated-water compartment and said fresh-water compartment offset a first distance according to the pressure difference, in a first direction that is parallel to a line connecting a cathode and an anode so as to form a first working state,
  • the pressure difference between the fresh-water compartment and the concentrated-water compartment is a positive pressure difference
  • the ion exchange membranes defining the fresh-water compartment move away from each other in the first direction and the second direction, respectively, so as to form a first width therebetween
  • the ion exchange membranes defining the concentrated-water compartment move toward each other in the first direction and the second direction, respectively, so as to form a second width therebetween, in which the first working state is defined by the first width and the second width.
  • the pressure difference between the fresh-water compartment and the concentrated-water compartment is a negative pressure difference
  • the ion exchange membranes defining the concentrated-water compartment move away from each other in the first direction and the second direction, respectively, so as to form a fourth width therebetween
  • the ion exchange membranes defining the fresh-water compartment move towards each other in the first direction and the second direction, respectively, so as to form a third width therebetween, in which the second working state is defined by the fourth width and the third width.
  • the present invention further provides a brine recycling system with automatic cleaning of ion exchange membranes, the system at least comprising the primary electrodialyzer and the bipolar membrane electrodialyzer of any of the preceding claims, wherein a fluid enters the primary electrodialyzer and/or the bipolar membrane electrodialyzer in a flowing direction perpendicular to a filtering direction of the ion exchange membranes, in which each of the primary electrodialyzer and the bipolar membrane electrodialyzer contains a plurality of bioinert particles that have a density smaller than a density of the fluid, the bioinert particles being configured to: be driven by the fluid to sink down from a water inlet of the primary electrodialyzer to a water outlet of the primary electrodialyzer, and be driven by buoyancy to float up from the water outlet of the primary electrodialyzer to the water inlet of the primary electrodialyzer; or be driven by the fluid to sink down from a water inlet of the bipolar membrane electrodialyzer to a water outlet of the bipolar membrane electro
  • the brine recycling system further comprises a waste water reduction unit, which is configured to: produce at least a first-concentration brine and a second-concentration brine having different salt contents using a first reverse osmosis device, a second reverse osmosis device and/or a combination thereof, and the fluid at least comprises the first-concentration brine and the second-concentration brine, in which the fluid enters the primary electrodialyzer in parts with at least different flow velocities and/or different densities thereof so that a pressure difference exists between adjacent said concentrated-water compartment and said fresh-water compartment, in which in condition that at least two said ion exchange membranes defining the concentrated-water compartment or the fresh-water compartment move towards each other due to a pressure difference to form a minimum distance, said part of the fluid entering a corresponding compartment has a density greater than the density of another part of the fluid entering an adjacent said compartment so that the bioinert particles therein float up with an increased velocity.
  • a waste water reduction unit which is configured to: produce at
  • the first bipolar membrane electrodialyzer and the second bipolar membrane electrodialyzer located downstream each have at least one third compartment, wherein the third compartment is adjacent to the first compartment, the fluid that has been treated by the concentrated-water compartment and is in the second circling path enters the second bipolar membrane electrodialyzer firstly and flows through the third compartment and the fifth compartment successively so as to be desalinated.
  • the brine recycling system further comprises a water softening module, an oxidation treatment module, and a pretreatment module, wherein raw water flows through and is treated by the water softening module, the oxidation treatment module, and the pretreatment module successively so as to become the fluid entering the first intermediate pool, in which the raw water is softened and filtered by the water softening module when flowing through a homogenizing drum, a coagulating pool, a flocculating pool, a settling pool and a sand filter pool, so as to become a first treated liquid.
  • the oxidation treatment module at least comprises an ozone generator for preparing ozone and an ozone exposure pool for oxygenation, in which the first treated liquid and the ozone are introduced into the ozone exposure pool simultaneously for oxygenation so as to produce a second treated liquid.
  • the pretreatment module at least comprises an ultrafiltration membrane device, a precision filter, and a reverse osmosis device, in which the second treated liquid is filtered by the ultrafiltration membrane device and the precision filter successively and then reverse-osmosis concentrated by the reverse osmosis device so as to produce the fluid.
  • the beneficial technical effects of the present invention include:
  • the present invention comprises a primary electrodialyzer and a bipolar membrane electrodialyzer, both of which use concentrated brine treated by the upstream equipment as the electrode solutions.
  • the bipolar membrane close to the anode compartment of the bipolar membrane electrodialyzer is configured into the work mode in which it generates OH - with greater efficiency.
  • the bipolar membrane close to the cathode compartment of the bipolar membrane electrodialyzer is configured into the work mode in which it generates H + with greater efficiency.
  • Electrode solutions of the bipolar membrane electrodialyzer neutralize with the weakly acidic or weakly alkaline electrode solutions generated by the primary electrodialyzer, so as to ensure that the pH value of the electrodes is always maintained within a desired range.
  • the present invention eliminates scales accumulated on the ion exchange membranes by dynamically adjusting their form, eliminates scales accumulated while the distance between the ion exchange membranes is small by increasing the distance between ion membranes of concentrated-water compartments or fresh-water compartments, thereby effectively inhibiting scaling of the ion exchange membranes.
  • forms of the filtering membranes change, due to the mechanical friction of bioinert particles to filtering membranes, scaling frequency of the filtering membranes can be effectively reduced.
  • Fig. 1 illustrates modular connections of preferred bipolar membrane processing modules according to the present invention
  • Fig. 2 is structural diagram of a preferred bipolar membrane electrodialyzer according to the present invention.
  • Fig. 3 illustrates modular connections of another preferred bipolar membrane processing modules according to the present invention
  • Fig. 4 illustrates modular connections of a preferred brine recycling system according to the present invention
  • Fig. 5 illustrates connections of the electronic modules of a preferred brine recycling system according to the present invention
  • Fig. 6 illustrates work form of ion exchange membranes of a preferred primary electrodialyzer according to the present invention
  • Fig. 7 illustrates another work form of ion exchange membranes of a preferred primary electrodialyzer according to the present invention.
  • Fig. 8 illustrates the working principle of preferred bioinert particles according to the present invention.
  • the term “may” is of permitted meaning (i.e., possibly) but not compulsory meaning (i.e., essentially) .
  • the terms “comprising” , “including” and “consisting” mean “comprising but not limited to” .
  • phrases “at least one” , “one or more” and “and/or” are for open expression and shall cover both connected and separate operations.
  • each of “at least one of A, B and C” , “at least one of A, B or C” , “one or more of A, B and C” , “A, B or C” and “A, B and/or C” may refer to A solely, B solely, C solely, A and B, A and C, B and C or A, B and C.
  • the term “automatic” and its variations refer to a process or operation that is done without physical, manual input. However, where the input is received before the process or operation is performed, the process or operation may be automatic, even if the process or operation is performed with physical or non-physical manual input. If such input affects how the process or operation is performed, the manual input is considered physical. Any manual input that enables performance of the process or operation is not considered “physical” .
  • the present invention provides a bipolar-membrane-based brine recycling system, at least comprising a bipolar membrane processing module 1.
  • the bipolar membrane processing module serves to process the solution entering therein in the manner of electrodialysis so as to obtain an acid solution, an alkali solution and a concentrated brine.
  • Fig. 2 shows the diagram of a preferred structure of the bipolar membrane electrodialyzer. As shown in Fig.
  • the bipolar membrane electrodialyzer at least comprises an electrode frame 103, an anode 104, a cathode 105, at least three bipolar membranes, at least one anion exchange membrane and at least one cation exchange membrane, wherein the anode and the cathode are fixed at the left side and right side of the electrode frame respectively opposite to each other.
  • two bipolar membranes are arranged parallel to each other so as to successively form a first compartment 109 and a third compartment 111 in the direction from the anode to the cathode.
  • the side close to the first compartment is an anion exchange membrane
  • the side close to the third compartment is a cation exchange membrane, so that OH - generated by the bipolar membrane can enter the first compartment and prevent decreasing of the pH value.
  • the side contacting the third compartment is an anion exchange membrane, so that the third compartment can receive H + and OH - from both bipolar membranes.
  • At least one bipolar membrane is arranged close to the cathode, so as to form at least one second compartment 110, wherein the side of the bipolar membrane contacting the second compartment is a cation exchange membrane, so that H + generated from ionization in the bipolar membrane can enter the second compartment.
  • the first compartment at the anode side is an anode compartment
  • the second compartment at the cathode side is a cathode compartment.
  • halogen gases such as chlorine generated at the anode increase significantly, which requires, for example, switch of the anode and the cathode to avoid continuous decreasing or increasing of pH.
  • the present invention by arranging corresponding bipolar membranes at the cathode side and the anode side, manages to generate OH - at the anode side to avoid pH decrease in the anode compartment, and generate H + at the cathode side to avoid pH increase in the cathode compartment.
  • At least one anion exchange membrane and at least one cation exchange membrane are arranged in the region between the second compartment and the third compartment, wherein in the direction from anode to cathode, the anion exchange membrane and the cation exchange membrane are arranged in sequence to define the fourth compartment 112, the fifth compartment 113 and the sixth compartment 114.
  • Compartments between the second compartment and the third compartment are arranged in a three-compartment two-bipolar-membrane manner, that is, the fourth compartment is an acid compartment, the fifth compartment is a desalting compartment and the sixth compartment is an alkali compartment.
  • the third compartment serves to receive halide ions such as chloridion from adjacent acid compartment, so as to enable desalination of the chloridion in subsequent desalting compartment, thereby effectively preventing the chloridion from converting to chlorine in the acid compartment and the anode compartment.
  • Liquid firstly enters the second bipolar membrane electrodialyzer downstream, then enters the first bipolar membrane electrodialyzer upstream, wherein in comparison with the flow mode that the liquid successively passes through the first bipolar membrane electrodialyzer and the second bipolar membrane electrodialyzer, the former recycles the chloridion in the acid compartment of the second bipolar membrane electrodialyzer downstream better, thereby improving quality of the desalted water in the desalting compartment of the second bipolar membrane electrodialyzer, and effectively inhibits continuous increase of chloridion concentration in the acid compartment and the anode compartment, thereby avoiding degradation of water quality caused by chloridion and ensuring quality consistency of the outlet water.
  • the bipolar membrane processing module at least comprises a first bipolar membrane electrodialyzer 101 and a second bipolar membrane electrodialyzer.
  • At least one electrodialysis processing module 2 is arranged upstream the bipolar membrane processing module, wherein the electrodialysis processing module at least comprises a primary electrodialyzer 201.
  • the primary electrodialyzer 201 consists of a cathode compartment 202, an anode compartment 203, fresh-water compartment 204 and concentrated-water compartment 205 defined by at least two anion exchange membrane and at least two cation exchange membrane arranged between the anode and the cathode.
  • an anion exchange membrane, a cation exchange membrane, an anion exchange membrane and a cation exchange membrane are successively arranged.
  • structures of the first bipolar membrane electrodialyzer and the second bipolar membrane electrodialyzer can be identical, or can be designed to possess different numbers of compartments according to practical situations.
  • the first bipolar membrane electrodialyzer is arranged downstream from the second bipolar membrane electrodialyzer to further concentrate the concentrated brine processed by the first bipolar membrane electrodialyzer. Arranging two bipolar membrane electrodialyzers ensures reasonable decrease of equipment cost in the premise of ensuring water processing quality.
  • a first intermediate pool 3 is arranged upstream from the electrodialysis processing module, and a second intermediate pool 4 is arranged downstream from the electrodialysis processing module, wherein the first intermediate pool serves to store the concentrated brine generated by the upstream equipment process temporarily, and the second intermediate pool serves to store the fresh water desalted by the electrodialysis processing module temporarily.
  • the first intermediate pool and the second intermediate pool are connected through a pipe so that concentrated brine in the first intermediate pool can enter the second intermediate pool through the pipe, wherein a control valve is arranged in the pipe connecting the first intermediate pool and the second intermediate pool, so as to control the pipe to close if necessary.
  • the second intermediate pool is equipped with at least two outlet pipes, wherein the two outlet pipes are connected with the concentrated-water compartment and the fresh-water compartment of the primary electrodialyzer respectively, and wherein the outlet of the fresh-water compartment is connected to the first intermediate pool by pipe so that fresh water in the fresh-water compartment can flow back to the first intermediate pool, and then can enter the fresh-water compartment multiple times to undergo multilevel processing to obtain fresh water with a much lower salt content.
  • the outlet of the concentrated-water compartment is connected to the inlet of the third compartment of the second bipolar membrane electrodialyzer by pipe.
  • the outlet of the third compartment of the second bipolar membrane electrodialyzer is connected to the inlet of the third compartment of the first bipolar membrane electrodialyzer.
  • the outlet of the third compartment of the first bipolar membrane electrodialyzer is connected to the inlet of the fifth compartment of the first bipolar membrane electrodialyzer.
  • the outlet of the fifth compartment of the first bipolar membrane electrodialyzer is connected to the inlet of the fifth compartment of the second bipolar membrane electrodialyzer.
  • the outlet of the fifth compartment of the second bipolar membrane electrodialyzer is connected to the second intermediate pool.
  • the outlet of the first intermediate pool is also connected to the inlets of the anode compartment of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer by pipe, respectively.
  • the outlets of the anode compartment of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer are connected to the first intermediate pool by pipe.
  • the outlet of the first intermediate pool is also connected to the inlets of the cathode compartments of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer by pipe, wherein the outlets of the cathode compartments of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer are connected to the first intermediate pool by pipe.
  • the control valve on the pipe connecting the first intermediate pool and the second intermediate pool opens, so that the treated liquid in the first intermediate pool can be transported to the second intermediate pool by, for example, lift pump.
  • a level monitor for example, is set in the second intermediate pool. When the liquid level of the fluid in the second intermediate pool monitored by the level monitor reaches a predetermined value, the control valve is closed to stop transporting treated liquid to the second intermediate pool.
  • the second intermediate pool comprises two chambers, one on the right side and the other on the left side. The treated liquid can be transported to, for example, the first chamber on the left side.
  • the treated liquid in the first chamber on the left side of the second intermediate pool can be circulated between the electrodialysis processing module and the second chamber on the right side of the second intermediate pool so that a first circling path 6 is formed.
  • the treated liquid in the first chamber enters the fresh-water compartment of the primary electrodialyzer through pipe, and fresh water desalted in the fresh-water compartment is transported to the second chamber through pipe for temporary storage.
  • the treated liquid in the first chamber can also be transported to the concentrated compartment of the primary electrodialyzer through pipe.
  • the treated liquid is further concentrated in the concentrated-water compartment, and then transported to the downstream bipolar membrane processing module for further treatment.
  • the treated liquid enters the concentrated-water compartment in a first direction of flow direction, and the treated liquid enters the fresh-water compartment in a second direction of flow direction, wherein the first direction and the second direction are opposite to each other.
  • the treated liquid flows from right to left in the concentrated-water compartment, and flows from left to right in the fresh-water compartment.
  • the concentration trend forms in terms of that the ion concentration gradually increases, i.e., the concentration of the treated liquid on the right side of the concentrated-water compartment is lower than that on the left side of the concentrated-water compartment.
  • the concentration of the inlet side of the fresh-water compartment is greater than that of the outlet side.
  • this section corresponds to the outlet side of the fresh-water compartment, and ion concentration of the solution on the outlet side of the fresh-water compartment is lower than that of the rest sections of the fresh-water compartment, while as for a section corresponding to the inlet side of the concentrated-water compartment, ion concentration of the solution on the inlet side of the concentrated-water compartment is also lower than that of the rest sections of the concentrated-water compartment, so that in the plane perpendicular to the first direction or the second direction, concentration difference between the concentrated-water compartment and the fresh-water compartment is minimal, thereby reducing the amount of water molecules diffusing from the fresh-water compartment into the concentrated-water compartment due to concentration difference, and effectively improving water production efficiency of the primary electrodialyzer.
  • the control valve between the first intermediate pool and the second intermediate pool is opened to replenish new treated liquid.
  • the first direction is opposite to the second direction, taking the right side of the primary electrodialyzer for example, in the process of desalting the fluid in the fresh-water compartment, ions are removed so that electrical conductivity exhibits a decreasing trend, and fluid in the concentrated-water compartment obtains ions from adjacent fresh-water compartments so that electrical conductivity exhibits a gradually increasing trend.
  • the first direction being opposite to the second direction renders that, in the plane perpendicular to the first direction or the second direction, electrical conductivity difference between the concentrated-water compartment and the fresh-water compartment is smaller. Smaller difference of electrical conductivity can avoid polarization and over decomposition of water, thereby effectively controlling scale generation.
  • the treated liquid in the first chamber on the left side of the second intermediate pool is circularly connected to the second intermediate pool so that a second circling path 7 is formed.
  • the treated liquid in the first chamber enters the concentrated-water compartment through pipe to be concentrated to obtain the concentrated liquid.
  • the concentrated liquid is then transported to the third compartment of the second bipolar membrane electrodialyzer and the third compartment of the first bipolar membrane electrodialyzer through pipe respectively.
  • the concentrated liquid treated in the third compartment of the first bipolar membrane electrodialyzer is then transported to the fifth compartment of the first bipolar membrane electrodialyzer to go through first stage desalting and obtain the first stage desalted liquid.
  • the first stage desalted liquid is then transported through pipe to the fifth compartment of the first bipolar membrane electrodialyzer to go through second stage desalting and obtain the second stage desalted liquid.
  • the second stage desalted liquid is then transported through pipe to the second chamber of the second intermediate pool for temporary storage.
  • the first intermediate pool also provides the anode compartments and the cathode compartments of the bipolar membrane processing module and the electrodialysis processing module with required electrode solutions through a third circling path 8 and a fourth circling path 9.
  • the third circling path at least comprises a first supply pipe 801 and a drain pipe 802.
  • the first supply pipe is directly connected to the first intermediated pool, and water inlets of the anode compartments of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer are connected to the first supply pipe respectively.
  • the fourth circling path at least comprises a second supply pipe 901 and a second drain pipe 902.
  • the second supply pipe is directly connected to the first intermediated pool, and water inlets of the cathode compartments of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer are connected to the first supply pipe respectively.
  • Water outlets of the cathode compartments of the first bipolar membrane electrodialyzer, the second bipolar membrane electrodialyzer and the primary electrodialyzer are connected to the second drain pipe respectively, wherein the second drain pipe is directly connected to the first intermediate pool. Due to characteristics of anode compartments and cathode compartments, oxidation reaction takes place in the anode compartment to generate H + , and reduction reaction takes place in the cathode compartment to generate OH - .
  • Bipolar membranes close to the anode compartments of the first bipolar membrane electrodialyzer and the second bipolar membrane electrodialyzer are configured into the work mode to produce OH - with higher efficiency, so that in the anode compartments, after neutralization with H + , part of OH - remain to keep the electrode solution flowing out of the anode compartments weakly alkaline.
  • the primary electrodialyzer doesn’t comprise a bipolar membrane, H + generated from oxidation cannot be neutralized, so that the electrode solution flowing out of its anode compartment is weakly acidic.
  • Bipolar membranes close to the cathode compartments of the first bipolar membrane electrodialyzer and the second bipolar membrane electrodialyzer are configured into the work mode to produce H + with higher efficiency, so that in the cathode compartments, after neutralization with OH - , part of H + remain to keep the electrode solution flowing out of the cathode compartments weakly acidic.
  • the primary electrodialyzer doesn’t comprise a bipolar membrane, OH - generated from reduction cannot be neutralized, so that the electrode solution flowing out of its cathode compartment is weakly alkaline.
  • Weakly acidic electrode solution flowing out of the cathode compartment of the bipolar membrane electrodialyzer can neutralize the weakly alkaline electrode solution flowing out of the cathode compartment of the primary electrodialyzer and flow back to the first intermediate pool.
  • the fourth compartments and the sixth compartments of the first bipolar membrane electrodialyzer and the second bipolar membrane electrodialyzer are acid compartments and alkali compartments respectively.
  • Required acid and alkali can be produced in the acid compartments and the alkali compartments, wherein, for example, fresh water, organic acids and inorganic acids can enter the fourth compartment of the first bipolar membrane electrodialyzer and the fourth compartment of the second bipolar membrane electrodialyzer successively to produce corresponding acid products.
  • the acid products can be transported to the third intermediate pool 10 for temporary storage.
  • fresh water or low-concentration alkali solution can enter the sixth compartment of the first bipolar membrane electrodialyzer and the sixth compartment of the second bipolar membrane electrodialyzer successively to produce corresponding alkali products.
  • the alkali products can be transported to the fourth intermediate pool 11 for temporary storage.
  • the third intermediate pool and the fourth intermediate pool can be connected to the fourth compartment and the sixth compartment of the first bipolar membrane electrodialyzer by pipe, and concentration of the acid products and alkali products can be gradually increased by constant circulation.
  • the fourth intermediate compartment is also connected to the first compartments and the second compartments of the first bipolar membrane electrodialyzer and the second bipolar membrane electrodialyzer by pipe to adjust their pH. Decrease of pH in the first compartments and the second compartments can be avoided to certain degree by adding alkali products in the fourth intermediate pool.
  • the present embodiment is further improvement based on Embodiment 1, and the repeated description is omitted herein.
  • the second intermediate pool comprises only one chamber and a water quality monitor 12 is arranged in the second intermediate pool, wherein the water quality monitor may include a first ion detector for monitoring chloridion concentration, a second ion detector for monitoring heavy metal ion concentration and small particle detector for monitoring colloid and suspension content.
  • the water quality monitor may include a first ion detector for monitoring chloridion concentration, a second ion detector for monitoring heavy metal ion concentration and small particle detector for monitoring colloid and suspension content.
  • the liquid in the second intermediate pool is circularly treated again through the first circling path and the second circling path.
  • Predetermined standard of the water quality monitor can be formulated according to practical situations. For example, when the fluid in the second intermediate pool is used for industry for irrigation, the metal ion concentration, suspension content, chloridion concentration can be a little higher than the standard for domestic water.
  • a pH sensor 14 is arranged in the first intermediate pool to monitor pH of the treated liquid in its chambers, wherein the first intermediate pool is also connected to the third intermediate pool and the fourth intermediate pool by pipe respectively, and control valves are set on the pipes connecting these pools to control connection and disconnection between the first intermediate pool and the third intermediate pool and/or the fourth intermediate pool.
  • the control valves are opened to adjust the pH. For example, when it detects that pH of the treated liquid in the first intermediate pool is too low, alkali products produced in the fourth intermediate pool are guided into the first intermediate pool to conveniently keep the pH within a desired range.
  • desalted liquid treated in the fifth compartment of the second bipolar membrane electrodialyzer can be connected to the fourth compartment and the fifth compartment of the first bipolar membrane electrodialyzer, wherein the fourth compartment of the first bipolar membrane electrodialyzer is connected to the fourth compartment of the second bipolar membrane electrodialyzer, and the sixth compartment of the first bipolar membrane electrodialyzer is connected to the sixth compartment of the second bipolar membrane electrodialyzer.
  • the present embodiment is further improvement based on former embodiments, and repeated description is omitted herein.
  • the present invention provides a bipolar-membrane-based brine recycling system, which system is equipped with the bipolar membrane processing module and electrodialysis processing module used in previous embodiments, wherein the brine recycling system further comprises a water softening module 15, an oxidation treatment module 16, a pretreatment module 17 and a dosing module 18, wherein the water softening module serves to soften the liquid, and the oxidation treatment module serves to oxidize the softened waste water to eliminate hazardous microorganism such as bacteria.
  • the pretreatment module preliminarily concentrates the waste water in a reverse osmosis manner so as to obtain waste water treated liquid with certain salt concentration.
  • the water softening module at least comprises a homogenizing drum 301, a coagulating pool 302, a flocculating pool 303, a settling pool 304 and a sand filter pool 305, wherein several lift pumps can be used to provide transfer driving force for transferring the waste water between the homogenizing drum, coagulating pool, flocculating pool, settling pool and sand filter pool.
  • the homogenizing drum serves to improve distribution homogeneity of distributed matter in the waste water, and it can cause relative movement of the waste water in the homogenizing drum by way of stirring or ultrasonic vibration, so as to produce a mixing and stirring effect.
  • NaOH or Na 2 CO 3 can be added into the homogenizing drum to pretreat the waste water.
  • the homogenizing drum is connected to the third intermediate pool and the fourth intermediate pool by pipe, and the waste water is softened by adding acid or alkali.
  • the coagulating pool serves to coagulate the waste water.
  • a coagulant for example is added in the waste water which is stirred adequately, so that the waste water and the coagulant are adequately mixed to form a large amount of flocculation groups.
  • the flocculating pool serves to flocculate the waste water.
  • a flocculant for example is added so that the large amount of flocculation groups in the coagulated waste water form big and dense alumen ustum.
  • the settling pool serves to settle the waste water so that large particles in the waste water precipitate to the bottom of the pool, and after precipitation, precipitants form mud and are then collected and removed from original waste water, so as to purify water quality.
  • the sand filter pool serves to preliminarily filter impurities such as suspension and colloid in the waste water to improve purity of waste water, so that the waste water will not easily contaminate membrane elements in subsequent treatment and cause scale or block on the membrane.
  • the dosing module serves to provide the water softening module with required agents.
  • the dosing module is connected to the coagulating pool, the flocculating pool and the homogenizing drum through dosing pipes. Dose control valves can be set in the dosing pipes to control adding amounts of required agents.
  • the oxidation treatment module can effectively eliminate hazardous microorganisms in the waste water, and it at least comprises an ozone generator 402, an offgas destructor 403, an ozone exposure pool 404, an oxygen generator 405, a refrigeration dryer 406 and a desiccant dryer 407.
  • Ozone can be generated using one of, for example, electrolytic process, nucleic radiation method, UV method, plasma method and corona discharge method. For example, air is pushed by an air compressor through the refrigeration dryer and the desiccant dryer to be dried and then to the oxygen generator to produce oxygen. The produced oxygen is then dust filtered, decompressed, stabilized and transferred into the ozone generator, and is converted into ozone under medium frequency high voltage discharge condition.
  • the generated ozone can be regulated by temperature, pressure and flow volume monitors, and then be transferred to the ozone exposure pool via outlet of the ozone generator.
  • Ozone can be applied by diffuser disks installed at the bottom of the ozone exposure pool.
  • the ozone exposure pool is arranged in an airproof manner to prevent ozone leakage, wherein the ozone exposure pool may comprise a water inlet, a water outlet, an air inlet and an air outlet.
  • Waste water treated by pretreatment unit can enter the ozone exposure pool via the water inlet, ozone enters the ozone exposure pool via the air inlet, and the offgas destructor is connected to the air outlet to receive ozone residue.
  • the offgas destructor facilitates ozone decomposition by heat catalysis, so that after decomposition, ozone concentration in the gas is below 0.1 ppm.
  • the pretreatment module at least comprises an ultrafiltration membrane device 501, a precision filter 502 and a reverse osmosis device 503, wherein the ultrafiltration membrane device is connected with the reverse osmosis device via the precision filter.
  • the ultrafiltration membrane device can use, for example, GTN-55-FR ultrafiltration membrane components, and realize filtration of waste water based on the ultrafiltration membrane components.
  • the membrane column of the ultrafiltration membrane device can use the internal pressure type, wherein water flows from inside to outside with positive pressure, raw water enters the membrane column from water inlet at the top of the membrane column, and under pressure effect, raw water at the inner side of the membrane filament permeates the membrane filament filtration membrane and enters the outside of the membrane filament, the permeated clear water gathers from clear water outlet at the bottom of the membrane column, enters the collecting pipe and then enters the ultrafiltration tank. Remaining concentrated water that doesn’t permeate the ultrafiltration membrane is collected in the reflux located downstream of the membrane, then recycled to the water inlet by the circulating pump at the bottom of the membrane column. Waste water treated by the ultrafiltration device is filtered again by the precision filter and then transported to the reverse osmosis device for reverse osmosis treatment.
  • the brine recycling system further comprises a control module 19, which is electrically connected with the control valves, the water quality monitor, the level monitor, the pH sensor and the dosing module, and generates control order by corresponding signals, so as to control corresponding modules to conduct corresponding actions.
  • a control module 19 which is electrically connected with the control valves, the water quality monitor, the level monitor, the pH sensor and the dosing module, and generates control order by corresponding signals, so as to control corresponding modules to conduct corresponding actions.
  • the water quality monitor detects that the water is not qualified, it can control devices such as the lift pump to transfer the treated liquid in the second intermediate pool to the bipolar membrane processing module and the electrodialysis processing module.
  • the water quality monitor detects that the water is qualified, it can control devices such as the lift pump to transfer the treated liquid in the second intermediate pool out of the brine recycling system.
  • saline waste water flows through the water softening module, the oxidation treatment module, the pretreatment module, the electrodialysis processing module and the bipolar membrane processing module successively to produce product water, acid products and alkali products.
  • the present embodiment is further improvement based on former embodiments, and repeated description is omitted herein.
  • Fig. 6 and Fig. 7 show two different work modes of the primary electrodialyzer. As shown in Fig. 6 and Fig. 7, the distance between the anion exchange membrane 107 and the cation exchange membrane 108 of the primary electrodialyzer can be adjusted. As shown in Fig. 6, in the first mode, anion exchange membrane and cation exchange membrane defining the fresh-water compartment exhibit an convex form, so that the fresh-water compartment has the greatest first width D 1 , and the adjacent concentrated-water compartment has the smallest second width D 2 , wherein the first width D 1 is greater than the second width D 2 . As shown in Fig.
  • the anion exchange membrane and cation exchange membrane exhibit a concave form, so that the fresh-water compartment has the smallest third width D 3 , and the adjacent concentrated-water compartment has the greatest fourth width D 4 , wherein the fourth width D 4 is greater than the third width D 3 .
  • the distance between the anion exchange membrane and the cation exchange membrane can be adjusted by controlling the pressure difference applied thereon.
  • the pressure of the fluid in the fresh-water compartment is higher than that of the adjacent concentrated-water compartment. Higher pressure in the fresh-water compartment renders the anion exchange membrane and the cation exchange membrane bulge towards the concentrated-water compartment, so as to exhibit an convex form.
  • Switching between the first mode and the second mode can be realized by causing positive pressure difference or negative pressure difference between two adjacent compartments.
  • curvature of the anion exchange membrane and cation exchange membrane can be simplistically calculated using the equation below based on mechanics theory of thin plates.
  • D max represents the maximum displacement the anion exchange membrane or the cation exchange membrane can reach.
  • C is a constant depending on the ratio of the width and the length of compartments. For example, C can be directly equal to the width of the fresh-water compartment divided by the length of the fresh-water compartment.
  • P represents pressure difference on the ion exchange membranes.
  • W represents the width of the fresh-water compartment.
  • H represents the length of the fresh-water compartment.
  • E represents elasticity modulus of corresponding ion exchange membranes.
  • the lateral direction of compartments refers to the direction parallel to the line connecting the anode and the cathode.
  • the longitudinal direction of compartments refers to the flow direction of the waste water therein.
  • pressure difference on the ion exchange membranes can be obtained by controlling the flow rate at the inlet and/or outlet of the compartment.
  • water inlet rate of the fresh-water compartment can be increased and the water outlet rate remains the same, so that pressure in the fresh-water compartment is higher than that in the adjacent compartment, and the ion exchange membrane protrudes outward to the concentrated-water compartment under the effect of the pressure difference.
  • water outlet rate of the fresh-water compartment can be increased and its water inlet rate remains unchanged, so that pressure in the fresh-water compartment is lower than that in the adjacent compartment.
  • pressure difference on the ion exchange membranes can be obtained by different pressures applied by a booster pump before concentrated brines of different concentration enter the bipolar membrane electrodialyzer.
  • pressure difference applied on the ion exchange membranes can be dynamically adjusted at least according to the type of the waste water, the elasticity modulus of the ion exchange membranes and the structure of the ion exchange membranes, so as to avoid shortening of lifespan of the ion exchange membranes due to too large pressure difference.
  • pressure difference on the ion exchange membranes is preferably set within the range of 10 Pa to 2500 Pa.
  • mode variation of the ion exchange membranes can be operated based on a time period T 1 . That is, the ion exchange membranes transform from an convex state to a concave state, or transform from a concave state to an convex state every T 1 .
  • Each mode variation of the ion exchange membranes can be operated by applying different pressure differences, so that bulge levels of two successive convex states are different. For example, when the ion exchange membrane is switched from the convex state to the concave state for the first time, the pressure difference applied is P 1 , then when the ion exchange membrane is switched from the concave state to the convex state, the applied pressure difference is P 2 .
  • the time period T1 of the mode variation of the ion exchange membranes can be determined according to the measured resistance of the fluid in the compartment. For example, resistance of the concentrated brine in the concentrated-water compartment is monitored, and when the resistance is below certain threshold, water inlet pressure and water outlet pressure are adjusted, and electrodes and inlet water type are exchanged by the control unit, so as to realize mode switch of the ion exchange membranes. Dynamic automatic adjustment of modes of ion exchange membranes is realized by monitoring, thereby effectively inhibiting scaling.
  • forms of the ion exchange membranes can be adjusted according to concentration difference of the fluids in two adjacent compartments.
  • a first reverse osmosis device 23 and a second reverse osmosis device 24 with different osmotic pressures are set on the first circling path 6 and the second circling path 7 respectively.
  • Fluids of different concentration levels are generated by the first reverse osmosis device 23 and the second reverse osmosis device 24, and enter the concentrated-water compartment and fresh-water compartment respectively.
  • anion exchange membranes and cation exchange membranes of the bipolar membrane electrodialysis are also configured into the work mode that has a first form and a second form.
  • a plurality of bioinert particles are also arranged in the bipolar membrane electrodialyzer.
  • Fig. 8 shows the schematic diagram of working principle of the bioinert particles according to the present invention. Taking the primary electrodialyzer for example, as shown in Fig. 8, the primary electrodialyzer is configured into the work mode in which the flow direction of the fluids in its concentrated-water compartment and fresh-water compartment is perpendicular to the ground, and into the work mode in which the height of its water inlet 21 from the ground is greater than the height of its water outlet from the ground.
  • a plurality of round-shaped bioinert particles 20 are arranged in the compartments defined by anion exchange membranes and cation exchange membranes.
  • fluid enters the concentrated-water compartment from water inlet 21 and flows out of the concentrated-water compartment from water outlet 22.
  • the shape of the bioinert particles 20 can be defined as globular, cylindrical or lentoid, wherein the surface roughness of the bioinert particles is smaller than 40 ⁇ m. Density of the bioinert particles is smaller than that of the fluid entering the concentrated-water compartment, so that they can automatically float due to buoyancy.
  • Filter nets can be arranged at the water inlet and water outlet, and mesh size of the filter nets is smaller than the diameter of the bioinert particles to keep the bioinert particles inside the concentrated-water compartment.
  • bioinert particles When fluid enters the concentrated-water compartment and fills up the concentrated-water compartment, bioinert particles at the water inlet, driven by the fluid entering from the water inlet at certain speed, sink to the water outlet. After they reach the water outlet, driven by buoyancy, they float up from the water outlet to the water inlet. During constant floating and sinking of the bioinert particles, rub cleaning of the ion exchange membranes is completed.
  • bioinert particles can be arranged in every compartment of the bipolar membrane electrodialyzer and the primary electrodialyzer.
  • the bioinert particles at least consist of epispastic polyurethane (PU) . Foaming treatment can effectively reduce its density, so that its density is smaller than that of the fluid.
  • PU epispastic polyurethane
  • Displacement of bioinert particles in the compartments cause physical and chemical cleaning to the ion exchange membranes.
  • Water inlet and water outlet of compartments are set in the middle in the width direction of the compartments. In the direction from top to bottom of the compartment, the fluid is always flowing from top to bottom, so that bioinert particles move from the middle of the compartment to the water outlet of the compartment.
  • bioinert particles move to the water outlet at the bottom of the compartment, due to buoyancy and impact of water flow, bioinert particles move to the ion exchange membrane with smaller water flow impact, and move from bottom to top at the ion exchange membrane.
  • a clockwise circling water flow and a counterclockwise circling water flow are formed inside the compartment.
  • the line connecting the water inlet and the water outlet of the compartment divides the compartment into two parts, the left part and the right part, wherein a clockwise circling water flow is formed at the left side of the compartment, and a counterclockwise circling water flow is formed at the right side of the compartment, and the bioinert particles flow in the direction of the circling water flow.
  • the bioinert particles can impact the ion exchange membrane better during floating so as to cause a rubbing effect, and further eliminate scales on the ion exchange membrane.
  • the bioinert particles are also configured into the work mode in which there is acidic or alkaline cleaning agent inside the bioinert particles, wherein cleaning agents set inside the bioinert particles are released to the compartment at a predetermined release rate through release channels.
  • the bioinert particles comprise hollow chambers for storing acidic or alkaline cleaning agents, and the hollow chambers are connected to external environment through holes with preset sizes.
  • the concentration of the cleaning agents in the hollow chambers is configured to be greater than that of the waste water in the compartment, so that the cleaning agents can enter the compartment by diffusion. Size of the holes can be set according to actual conditions of waste water and concentration of additive cleaning agents, so as to meet the work duration of bioinert particles.
  • small holes and high-concentration cleaning agents working together achieves a longer work duration than the combination of big holes and low-concentration cleaning agents.
  • bioinert particles continue releasing cleaning agents, so as to effectively inhibiting scaling on filtration membranes.

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Abstract

Un système de recyclage de saumure à base de membrane bipolaire comprend un premier compartiment (109), un deuxième compartiment (110) et un troisième compartiment (111), l'eau d'entrée circulant, sous la forme d'une solution d'électrode, dans un troisième chemin circulaire (8) défini par le premier compartiment (109), le compartiment d'anode (203) du électrodialyseur primaire (201) et le premier groupe intermédiaire (3), et dans un quatrième chemin circulaire (9) défini par le second compartiment (110), le compartiment de cathode et le premier groupe intermédiaire (3) respectivement, le premier compartiment (109) étant configuré dans le mode de travail dans lequel le fluide traité neutralise ainsi le fluide acide obtenu par le traitement du compartiment d'anode (203) dans le troisième chemin circulaire (8), et le deuxième compartiment (110) est configuré dans le mode de travail dans lequel le fluide traité neutralise ainsi le fluide alcalin produit par le traitement du compartiment de cathode (202) dans le quatrième chemin circulaire (9).
PCT/CN2019/073405 2018-10-17 2019-01-28 Système de recyclage de saumure à base de membrane bipolaire WO2020077918A1 (fr)

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CN109250846A (zh) * 2018-10-18 2019-01-22 倍杰特集团股份有限公司 一种抑制结垢的含盐废水处理系统

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CN114656070A (zh) * 2020-12-24 2022-06-24 广东栗子科技有限公司 一种长效净水系统、控制方法和净水设备
CN117700057A (zh) * 2024-02-06 2024-03-15 威海天辰环保股份有限公司 一种高盐度生产废水的处理装置

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