Bipolar membrane electrodialysis device and use method thereof

Abstract

The invention discloses a bipolar membrane electrodialysis device and a use method thereof, and relates to the technical field of bipolar membrane electrodialysis, the bipolar membrane electrodialysis device comprises a pre-storage pool, the output end of the pre-storage pool is provided with a first pumping pipeline, the output end of the first pumping pipeline is provided with a rotational flow screening mechanism, and the output end of the first pumping pipeline is provided with a second pumping pipeline; a second pumping pipeline is installed at the output end of the cyclone screening mechanism, a pH adjusting mechanism is installed at the output end of the second pumping pipeline, the output end of the pH adjusting mechanism is connected with an ultrafiltration membrane mechanism through a third pumping pipeline, and a sediment collecting pipe is installed on the outer wall of the ultrafiltration membrane mechanism. And the sediment collecting pipe is communicated with the pre-storage pool through a reflux pumping pipeline. According to the scheme, the problems that sodium sulfate high-salinity wastewater is adopted as saline water during treatment by an existing system, pre-precipitation and flocculent precipitation treatment are needed, the process of waiting for static precipitation is time-consuming and labor-consuming, and the treatment efficiency of the whole process is influenced are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of bipolar membrane electrodialysis, in particular to a bipolar membrane electrodialysis device and a method for using the same. Background Art

[0002] A bipolar membrane is a new type of ion exchange composite membrane, typically composed of a cation exchange layer, an interfacial hydrophilic layer, and an anion exchange layer. It is a true reactive membrane. Under the influence of a DC electric field, the bipolar membrane dissociates water, producing hydrogen ions and hydroxide ions on either side of the membrane. Leveraging this characteristic, a bipolar membrane electrodialysis system, combining a bipolar membrane with other bipolar membranes, acid separators, anion separators, salt separators, cation separators, and alkaline separators, can convert salts in aqueous solutions into their corresponding acids and bases without introducing new components. This method is called bipolar membrane electrodialysis.

[0003] Current bipolar membrane electrodialysis treatment systems, such as announcement number CN118270956A, a bipolar membrane electrodialysis treatment system and wastewater treatment method, first pre-precipitate the mine wastewater brine to remove dense solid suspended particles, and then add alkali and barium salt chemicals for mixed precipitation to remove heavy metals and sulfates.

[0004] However, the above system uses mining wastewater as brine during treatment, which requires pre-precipitation and flocculation sedimentation treatment. The waiting process for static sedimentation is time-consuming and labor-intensive, affecting the treatment efficiency of the overall process. To this end, we provide a bipolar membrane electrodialysis device and its use method. Summary of the Invention

[0005] The object of the present invention is to provide a bipolar membrane electrodialysis device and a method for using the same, so as to solve the problem that the existing system proposed in the above background technology uses sodium sulfate high-salt wastewater as brine during treatment, which requires pre-precipitation and flocculation precipitation treatment, and the waiting process for static precipitation is time-consuming and labor-intensive, affecting the treatment efficiency of the overall process.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solution: a bipolar membrane electrodialysis device, comprising a pre-storage tank, wherein the output end of the pre-storage tank is equipped with a first pumping pipeline, the output end of the first pumping pipeline is equipped with a cyclone screening mechanism, the output end of the cyclone screening mechanism is equipped with a second pumping pipeline, the output end of the second pumping pipeline is equipped with a pH adjustment mechanism, the output end of the pH adjustment mechanism is connected to an ultrafiltration membrane mechanism via a third pumping pipeline, a sediment manifold is installed on the outer wall of the ultrafiltration membrane mechanism, the sediment manifold is connected to the pre-storage tank via a reflux pumping pipeline, the output end of the ultrafiltration membrane mechanism is equipped with a fourth pumping pipeline, the output end of the fourth pumping pipeline is equipped with an ion exchange treatment mechanism, the output end of the ion exchange treatment mechanism (8) is equipped with a circulation input pipe group (901), and the output end of the circulation input pipe group (901) is equipped with a bipolar membrane dialysis mechanism (9).

[0007] Preferably, the pre-storage tank includes a tank body, a water inlet pipe is installed above the rear end of the tank body, a bracket is installed on the upper end of the tank body, and a plurality of brackets are provided, a sprocket chain transmission mechanism is installed on the upper end of the bracket, and a stirring paddle is installed on the lower end of each of the brackets, the upper end of the stirring paddle passes through and extends to the interior of the sprocket chain transmission mechanism, and a sprocket is installed, and adjacent sprockets are connected by chain transmission, an asynchronous motor is installed on the upper end of the sprocket chain transmission mechanism, and the output end of the asynchronous motor passes through and extends to the interior of the sprocket chain transmission mechanism, and is connected to one of the sprockets.

[0008] Preferably, the cyclone screening mechanism includes a conical screening tank and a separator temporary storage box, and the separator temporary storage box is installed at the lower end of the conical screening tank, a feed port connected to the first pumping pipeline is provided on one side of the conical screening tank, a discharge port connected to the second pumping pipeline is provided at the upper end of the conical screening tank, and a discharge valve is installed at the front end of the separator temporary storage box.

[0009] Preferably, the pH adjustment mechanism includes an adjustment box, a pH sensor is installed on the adjustment box, and the detection end of the pH sensor passes through and extends into the interior of the adjustment box, and adjustment tubes are installed on both sides of the rear upper end of the adjustment box, and the two adjustment tubes are respectively connected to the H2SO4 storage tank and the Na2CO3 and NaOH storage tanks.

[0010] Preferably, the ultrafiltration membrane mechanism includes a first membrane shell and a second membrane shell, the upper ends of the first membrane shell and the second membrane shell are connected by a connecting pipe, a connecting frame is installed between the first membrane shell and the second membrane shell, and a support frame is installed on the outer wall of the connecting frame.

[0011] Preferably, the interior of the first membrane shell is a microfiltration membrane with a pore size of 0.1μm, and the interior of the second membrane shell is an ultrafiltration membrane with a pore size of 0.02μm. The lower ends of the first membrane shell and the second membrane shell are both equipped with electric three-way valves, and the electric three-way valve branch is connected to the backwash pipeline.

[0012] Preferably, the bipolar membrane dialysis mechanism (9) includes a plurality of bipolar membrane dialysis units (903), the plurality of bipolar membrane dialysis units (903) are arranged in series, a circulation input pipe group (901) is installed at the bottom of the bipolar membrane dialysis unit (903), the circulation input pipe group (901) includes a circulation alkali input pipe, a concentrated salt input pipe, and a circulation acid input pipe, and an output pipe group (902) is installed at the upper end of the bipolar membrane dialysis mechanism (9), the output pipe group (902) includes a dilute alkali output pipe, a dilute salt water output pipe, and a dilute acid output pipe.

[0013] Preferably, an anode plate (904) is installed on the front end surface of the inner wall of the bipolar membrane dialysis unit (903), and a cathode plate (905) is installed on the rear end surface of the inner wall of the bipolar membrane dialysis unit (903).

[0014] Preferably, a membrane stack (906) arranged in the order of bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, and alkali separator is installed between the anode plate (904) and the cathode plate (905).

[0015] Preferably, a method for using a bipolar membrane electrodialysis device comprises the following steps:

[0016] Step 1: Sodium sulfate high-salt wastewater is used as brine, and the brine is pre-stored in a pre-storage tank. The asynchronous motor and sprocket chain mechanism drive the multiple sets of stirring paddles located on the upper end bracket of the pre-storage tank to rotate, thereby disturbing the tank body and preventing the sodium sulfate high-salt wastewater from accumulating and precipitating.

[0017] Step 2: The brine is pumped from the first pumping pipeline to the cyclone screening mechanism. The cyclone screening mechanism has a conical sieve cavity structure. When the brine enters, the centrifugal force causes the heavy particles inside, such as silt, to move outwards and slide down the inner wall to the separation temporary storage box, while the liquid is pumped out through the discharge port.

[0018] Step 3: The liquid that has passed through the cyclone screening mechanism enters the pH adjustment mechanism under the action of the second pumping pipeline, passes through the microfiltration membrane to intercept the large particles of colloid and suspended matter, and then passes through the ultrafiltration membrane to remove small molecular precipitates;

[0019] Step 4: The liquid filtered by the pH adjustment mechanism enters the ultrafiltration membrane mechanism through the third pumping pipeline; the pH value of the brine is detected by the pH sensor, and the inlet pH is stabilized to the suitable range of 9-11 for the bipolar membrane. If the pH is greater than 11, H2SO4 is added; if the pH is lower than 9, NaOH is added, and Na2CO3 is added for precipitation to remove calcium and magnesium ions;

[0020] Step 5: The liquid passing through the ultrafiltration membrane mechanism enters the ion exchange treatment mechanism through the fourth pumping pipeline.

[0021] Step 6: The brine after ion exchange treatment enters the bipolar membrane dialysis mechanism along the circulation input pipe group. Each bipolar membrane dialysis unit of the bipolar membrane dialysis mechanism has positive and negative electrodes on both sides. The bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, and alkali separator are arranged in series between the positive and negative electrodes. After the solutions of circulating alkali, brine, and circulating acid enter the unit, under the action of the DC electric field, the ions in the circulating alkali, brine, and circulating acid are directed to migrate, so that the bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, and alkali separator are connected in series to form an alkali chamber, a brine chamber, and an acid chamber. The dilute alkali output pipe, dilute brine output pipe, and dilute acid output pipe respectively output the dilute alkali, dilute brine, and dilute acid for subsequent treatment.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention adopts deflocculation treatment, and the entire treatment process relies entirely on physical separation, such as a cyclone screening mechanism and an ultrafiltration membrane mechanism, as well as ion exchange treatment. No coagulant needs to be added, and the flocculation step is completely avoided, which significantly shortens the process flow and reduces operating costs. It is more suitable for the treatment of sodium sulfate high-salt wastewater with high turbidity, high hardness, and complex metal precipitates. It solves the problem that the existing system uses sodium sulfate high-salt wastewater as brine during treatment, which requires pre-precipitation and flocculation precipitation treatment, and the process of waiting for static precipitation is time-consuming and labor-intensive, affecting the treatment efficiency of the overall process.

[0024] 2. The bipolar membrane dialysis mechanism of the present invention includes a bipolar membrane dialysis unit, an anode plate is installed at the front end of the inner wall of the bipolar membrane dialysis unit, and a cathode plate is installed at the rear end of the inner wall of the bipolar membrane dialysis unit. A membrane stack composed of a bipolar membrane, an acid separator, a negative membrane, a salt separator, a positive membrane, and an alkali separator assembled in series in sequence is installed between the anode plate and the cathode plate. The acid chamber in the bipolar membrane dialysis mechanism produces sulfuric acid (H2SO4), and the alkali chamber produces sodium hydroxide (NaOH) by electrolysis. When the circulating alkali, brine, and circulating acid enter the membrane stack, the acid chamber, salt chamber, and alkali chamber are arranged in parallel, so that the circulating alkali, brine, and circulating acid can be electrochemically treated throughout the entire process of inward circulation. The membrane stack assembled in series is used to extend the time that the circulating alkali, brine, and circulating acid remain in the membrane stack, thereby further improving the bipolar membrane electrolysis effect.

[0025] 3. The ultrafiltration membrane mechanism of the present invention has a microfiltration membrane with a pore size of 0.1μm inside the first membrane shell, and an ultrafiltration membrane with a pore size of 0.02μm inside the second membrane shell. The lower ends of the first membrane shell and the second membrane shell are both equipped with electric-controlled three-way valves, and the electric-controlled three-way valve branch is connected to the backwash pipeline. The liquid entering the ultrafiltration membrane mechanism first passes through the microfiltration membrane to intercept large particle colloids and suspended matter, and then the ultrafiltration membrane removes small molecular precipitates. The end-treated dilute brine can be used for the backwash operation of the first membrane shell and the second membrane shell after desalination treatment. During backwashing, the electric-controlled three-way valves at the lower ends of the first membrane shell and the second membrane shell are switched to the backwash pipeline, and dilute brine is fed in reverse to remove impurities intercepted on the surface of the filter membrane to ensure the subsequent use effect.

[0026] 4. In the present invention, the sediment treated by the ultrafiltration membrane can be pumped to the pre-storage tank through the reflux pumping pipeline. Under the action of the stirring mechanism of the pre-storage tank, the sediment is mixed with the original sludge in the brine, which acts as a natural adsorbent to increase the heavy content in the water and improve the effect of subsequent cyclone screening. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the pre-storage pool structure of the present invention;

[0029] Figure 3 It is a schematic structural diagram of the cyclone screening mechanism of the present invention;

[0030] Figure 4 It is a schematic structural diagram of the ultrafiltration membrane mechanism of the present invention;

[0031] Figure 5 Schematic diagram of the ion exchange treatment mechanism of the present invention;

[0032] Figure 6 Schematic diagram of the bipolar membrane dialysis mechanism structure of the present invention;

[0033] Figure 7 Schematic diagram of the pH adjustment mechanism of the present invention;

[0034] Figure 8 Schematic diagram of the internal structure of the bipolar membrane dialysis unit of the present invention;

[0035] In the figure: 1. Pre-storage tank; 101. Tank body; 102. Water inlet pipe; 103. Bracket; 104. Sprocket chain transmission mechanism; 105. Asynchronous motor; 106. Agitator; 2. First pumping pipeline; 3. Cyclone screening mechanism; 301. Conical screening tank; 302. Feed inlet; 303. Discharge outlet; 304. Separate temporary storage box; 305. Discharge valve; 4. Second pumping pipeline; 5. pH adjustment mechanism; 501. Adjustment box; 502. pH sensor; 5 03. Regulating tube; 6. Ultrafiltration membrane mechanism; 601. First membrane shell; 602. Second membrane shell; 603. Connecting pipe; 604. Connecting frame; 605. Support frame; 606. Electric-controlled three-way valve; 8. Ion exchange treatment mechanism; 7. Third pumping pipeline; 9. Bipolar membrane dialysis mechanism; 901. Circulation input pipe group; 902. Output pipe group; 903. Bipolar membrane dialysis unit; 904. Anode plate; 905. Cathode plate; 906. Membrane stack; 10. Fourth pumping pipeline. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0037] See also Figure 1-8 The present invention provides an embodiment: a bipolar membrane electrodialysis device, comprising a pre-storage tank 1, wherein a first pumping pipeline 2 is installed at the output end of the pre-storage tank 1, a cyclone screening mechanism 3 is installed at the output end of the first pumping pipeline 2, a second pumping pipeline 4 is installed at the output end of the cyclone screening mechanism 3, a pH adjustment mechanism 5 is installed at the output end of the second pumping pipeline 4, the output end of the pH adjustment mechanism 5 is connected to an ultrafiltration membrane mechanism 6 through a third pumping pipeline 7, a sediment manifold 11 is installed on the outer wall of the ultrafiltration membrane mechanism 6, the sediment manifold 11 is connected to the pre-storage tank 1 through a reflux pumping pipeline 12, a fourth pumping pipeline 10 is installed at the output end of the ultrafiltration membrane mechanism 6, an ion exchange treatment mechanism 8 is installed at the output end of the fourth pumping pipeline 10, a circulation input pipe group 901 is installed at the output end of the ion exchange treatment mechanism 8, and a bipolar membrane dialysis mechanism 9 is installed at the output end of the circulation input pipe group 901.

[0038] See also Figure 2The pre-storage tank 1 includes a tank body 101, a water inlet pipe 102 is installed above the rear end of the tank body 101, a bracket 103 is installed on the upper end of the tank body 101, and a plurality of brackets 103 are provided, a sprocket chain transmission mechanism 104 is installed on the upper end of the bracket 103, and a stirring paddle 106 is installed on the lower end of each bracket 103. The upper end of the stirring paddle 106 passes through and extends to the interior of the sprocket chain transmission mechanism 104, and is equipped with a sprocket. Adjacent sprockets are driven by a chain. The sprocket and chain belt transmission mechanism 104 is connected, and an asynchronous motor 105 is installed at the upper end of the asynchronous motor 105. The output end of the asynchronous motor 105 passes through and extends to the interior of the sprocket and chain belt transmission mechanism 104, and is connected to one of the sprockets. The brine is pre-stored in the pre-storage tank 1, and is driven by the asynchronous motor 105 and the sprocket and chain belt mechanism to drive the multiple groups of stirring paddles 106 located on the upper end bracket 103 of the pre-storage tank 1 to rotate, thereby disturbing the tank body to prevent the sodium sulfate high-salt wastewater from accumulating and precipitating.

[0039] See also Figure 3 The cyclone screening mechanism 3 includes a conical screening tank 301 and a separator storage box 304, and the separator storage box 304 is installed at the lower end of the conical screening tank 301. A feed port 302 connected to the first pumping pipeline 2 is provided on one side of the conical screening tank 301, and a discharge port 303 connected to the second pumping pipeline 4 is provided at the upper end of the conical screening tank 301. A discharge valve 305 is installed at the front end of the separator storage box 304. The cyclone screening mechanism 3 is a conical sieve cavity structure. When brine enters, under the action of centrifugal force, the heavy particles inside it, such as mud and sand, move outward and slide down the inner wall to the separator storage box 304, while the liquid is pumped out along the discharge port 303. The separator storage box 304 can be replaced with a screw conveyor as needed to realize automatic sewage discharge and facilitate continuous treatment.

[0040] See also Figure 7 The pH adjustment mechanism 5 includes a regulating box 501, on which a pH sensor 502 is installed, and the detection end of the pH sensor 502 passes through and extends into the interior of the regulating box 501. Regulating tubes 503 are installed on both sides of the rear upper end of the regulating box 501. The two regulating tubes 503 are respectively connected to the H2SO4 storage tank and the Na2CO3 and NaOH storage tanks. The pH sensor 502 can detect the pH value of the brine. If the pH is greater than 11, H2SO4 is added. If the pH is lower than 9, NaOH is added to stabilize the pH of the inlet water to the suitable range of 9-11 for the bipolar membrane, and Na2CO3 is added for precipitation to remove calcium and magnesium ions.

[0041] See also Figure 4The ultrafiltration membrane mechanism 6 includes a first membrane shell 601 and a second membrane shell 602. The upper ends of the first membrane shell 601 and the second membrane shell 602 are connected by a connecting pipe 603. A connecting frame 604 is installed between the first membrane shell 601 and the second membrane shell 602. A supporting frame 605 is installed on the outer wall of the connecting frame 604. The interior of the first membrane shell 601 is a microfiltration membrane with a pore size of 0.1 μm, and the interior of the second membrane shell 602 is an ultrafiltration membrane with a pore size of 0.02 μm. The lower ends of the first membrane shell 601 and the second membrane shell 602 are both equipped with an electrically controlled three-way valve 606, and the branch pipe of the electrically controlled three-way valve 606 is connected to the backwash pipeline. The liquid entering the ultrafiltration membrane mechanism 6 is first intercepted by the microfiltration membrane. The large particle colloids and suspended matter are removed, and the small molecular precipitates are removed by the ultrafiltration membrane. The dilute brine treated at the end can be used for the backwash operation of the first membrane shell 601 and the second membrane shell 602 after desalination treatment. During backwashing, the electric-controlled three-way valve 606 at the lower end of the first membrane shell 601 and the second membrane shell 602 is switched to the backwash pipeline, and the dilute brine is fed in reverse to remove the impurities trapped on the surface of the filter membrane to ensure the subsequent use effect. The precipitate produced by ultrafiltration can be pumped to the pre-storage tank 1 through the reflux pumping pipeline (not shown in the figure). Under the action of the stirring mechanism of the pre-storage tank 1, the precipitate is mixed with the original sludge in the brine, which acts as a natural adsorbent to increase the heavy matter in the water and improve the effect of subsequent cyclone screening.

[0042] See also Figure 6 and Figure 8 The bipolar membrane dialysis mechanism 9 includes a plurality of (3-4) bipolar membrane dialysis units 903, and the plurality of bipolar membrane dialysis units 903 are arranged in series. A circulation input pipe group 901 is installed at the bottom of the bipolar membrane dialysis unit 903, and the circulation input pipe group 901 includes a circulation alkali input pipe, a concentrated salt input pipe, and a circulation acid input pipe. The upper end of the bipolar membrane dialysis mechanism 9 is installed with an output pipe group 902, and the output pipe group 902 includes a dilute alkali output pipe, a dilute salt water output pipe, and a dilute acid output pipe. The front end surface of the inner wall of the bipolar membrane dialysis unit 903 is installed with an anode plate 904, and the rear end surface of the inner wall of the bipolar membrane dialysis unit 903 is installed with a cathode plate 905, a membrane stack 906 arranged in the order of a bipolar membrane, an acid separator, a negative membrane, a salt separator, a positive membrane, and an alkali separator is installed between the anode plate 904 and the cathode plate 905. The bipolar membrane, the acid separator, the negative membrane, the salt separator, the positive membrane, and the alkali separator are arranged in series between the positive and negative electrodes. After the circulating alkali, the brine, and the circulating acid enter the unit, the ions in the circulating alkali, the brine, and the circulating acid are caused to migrate in a directional manner under the action of the DC electric field, so that the bipolar membrane, the acid separator, the negative membrane, the salt separator, the positive membrane, and the alkali separator are connected in series to form an alkali chamber, a salt chamber, and an acid chamber. The dilute alkali, dilute brine, and dilute acid are respectively discharged through the dilute alkali output pipe, the dilute brine output pipe, and the dilute acid output pipe;

[0043] When the circulating alkali, brine, and circulating acid enter the membrane stack 906, the acid chamber, salt chamber, and alkali chamber are arranged in parallel, so that the circulating alkali, brine, and circulating acid can be electrochemically treated throughout the entire process of inward circulation, thereby extending the time that the circulating alkali, brine, and circulating acid remain in the membrane stack 906;

[0044] The specific composition of the bipolar membrane layer is as follows:

[0045] Cation exchange layer (CEM): contains sulfonic acid groups (-SO3H), whose main function is to allow cations (such as H+) to pass through and block anions;

[0046] Anion exchange layer (AEM): containing quaternary ammonium groups (-NR3 + ), whose main function is to allow anions (such as OH-) to pass through and block cations;

[0047] Intermediate layer (catalytic layer): The thickness is only micron-level, containing hydrophilic materials (such as polyvinyl alcohol), which reduces the water dissociation energy barrier. It is located between the anionic membrane and the cation membrane and is responsible for the dissociation of water molecules into H+ and OH-;

[0048] The bipolar membrane electrolyzer for sodium sulfate has a three-chamber structure, achieving co-generation of acid and alkali. The components include a bipolar membrane (BPM), an anion membrane (AEM), and a cation membrane (CEM). The assembly order of the membrane stack is cathode plate, bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, alkali separator, bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, alkali separator... Assembled in series, the order of bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, alkali separator is assembled into a small unit. Multiple (usually 3-4) independent small units connected in series are then assembled into a membrane stack. The concentrated acid, alkali, and salt solutions entering and exiting each small unit are independent. The membrane stack is equipped with three flow channels, which respectively discharge concentrated alkali, concentrated salt, and concentrated acid into the alkali tank, salt tank, and acid tank. The dilute alkali, dilute brine, and dilute acid then circulate back from the alkali tank, salt tank, and acid tank to the three flow channels in the membrane stack.

[0049] See also Figure 1-8 A method for using a bipolar membrane electrodialysis device comprises the following steps:

[0050] Step 1: Sodium sulfate high-salt wastewater is used as brine, and the brine is pre-stored in a pre-storage tank 1. The asynchronous motor 105 and the sprocket chain mechanism drive the multiple sets of stirring paddles 106 located on the upper end bracket 103 of the pre-storage tank 1 to rotate, thereby disturbing the tank body and preventing the sodium sulfate high-salt wastewater from accumulating and precipitating.

[0051] Step 2: The brine is pumped from the first pumping line 2 to the cyclone screening mechanism 3. The cyclone screening mechanism 3 has a conical sieve cavity structure. When the circulating alkali, brine, and circulating acid enter, the centrifugal force causes heavy particles such as silt to move outward and slide down the inner wall to the separator temporary storage box 304, while the liquid is pumped out through the discharge port 303.

[0052] Step 3: The brine after the cyclone screening mechanism 3 enters the pH adjustment mechanism 5 under the action of the second pumping pipeline 4. The pH value of the brine is detected by the pH sensor 502, and the pH of the inlet water is stabilized to the suitable range of 9-11 for the bipolar membrane. If the pH is greater than 11, H2SO4 is added. If the pH is lower than 9, NaOH is added, and Na2CO3 is added to precipitate and remove calcium and magnesium ions;

[0053] Step 4: The liquid filtered by the pH adjustment mechanism 5 enters the ultrafiltration membrane mechanism 6 under the action of the third pumping pipeline 7, and is intercepted by the microfiltration membrane to retain large particles of colloid and suspended matter, and then the ultrafiltration membrane removes small molecular precipitates;

[0054] Step 5: The liquid passing through the ultrafiltration membrane mechanism 6 enters the ion exchange treatment mechanism 8 through the fourth pumping pipeline 10.

[0055] Step 6: The brine after ion exchange treatment enters the bipolar membrane dialysis mechanism 9 along the circulation input pipe group 901. Each bipolar membrane dialysis unit 903 of the bipolar membrane dialysis mechanism 9 has positive and negative electrodes on both sides. The bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, and alkali separator are arranged in series between the positive and negative electrodes. After the circulating alkali, brine, and circulating acid enter the unit, under the action of the DC electric field, the ions in the circulating alkali, brine, and circulating acid are caused to migrate in a direction, so that the bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, and alkali separator are connected in series to form an alkali chamber, a salt chamber, and an acid chamber. The dilute alkali, dilute brine, and dilute acid are respectively discharged through the dilute alkali output pipe, the dilute brine output pipe, and the dilute acid output pipe for subsequent treatment.

[0056] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A bipolar membrane electrodialysis device comprising a pre-storage tank (1), characterized in that: The output end of the pre-storage tank (1) is equipped with a first pumping pipeline (2), the output end of the first pumping pipeline (2) is equipped with a cyclone screening mechanism (3), the output end of the cyclone screening mechanism (3) is equipped with a second pumping pipeline (4), the output end of the second pumping pipeline (4) is equipped with a pH adjustment mechanism (5), the output end of the pH adjustment mechanism (5) is connected to an ultrafiltration membrane mechanism (6) via a third pumping pipeline (7), and a sedimentation membrane mechanism (6) is installed on the outer wall of the ultrafiltration membrane mechanism (6). The sediment confluence pipe (11) is connected to the pre-storage tank (1) through a reflux pumping pipeline (12); the output end of the ultrafiltration membrane mechanism (6) is installed with a fourth pumping pipeline (10); the output end of the fourth pumping pipeline (10) is installed with an ion exchange treatment mechanism (8); the output end of the ion exchange treatment mechanism (8) is installed with a circulation input pipe group (901); and the output end of the circulation input pipe group (901) is installed with a bipolar membrane dialysis mechanism (9).

2. A bipolar membrane electrodialysis device according to claim 1, characterized in that: The pre-storage tank (1) comprises a tank body (101), a water inlet pipe (102) is installed above the rear end of the tank body (101), a bracket (103) is installed at the upper end of the tank body (101), and a plurality of brackets (103) are provided, a sprocket chain transmission mechanism (104) is installed at the upper end of the bracket (103), and a stirring paddle (106) is installed at the lower end of each of the brackets (103), the upper end of the stirring paddle (106) passes through and extends to the interior of the sprocket chain transmission mechanism (104), and is installed with a sprocket, and adjacent sprockets are connected by chain transmission, an asynchronous motor (105) is installed at the upper end of the sprocket chain transmission mechanism (104), and the output end of the asynchronous motor (105) passes through and extends to the interior of the sprocket chain transmission mechanism (104) and is connected to one of the sprockets.

3. A bipolar membrane electrodialysis device according to claim 2, characterized in that: The cyclone screening mechanism (3) comprises a conical screening tank (301) and a separator temporary storage box (304), wherein the separator temporary storage box (304) is installed at the lower end of the conical screening tank (301); a feed port (302) connected to a first pumping pipeline (2) is provided on one side of the conical screening tank (301); a discharge port (303) connected to a second pumping pipeline (4) is provided at the upper end of the conical screening tank (301); and a discharge valve (305) is installed at the front end of the separator temporary storage box (304).

4. A bipolar membrane electrodialysis device according to claim 3, characterized in that: The pH adjustment mechanism (5) comprises an adjustment box (501), a pH sensor (502) is installed on the adjustment box (501), and the detection end of the pH sensor (502) passes through and extends into the interior of the adjustment box (501), and adjustment tubes (503) are installed on both sides of the rear upper end of the adjustment box (501), and the two adjustment tubes (503) are respectively connected to the H2SO4 storage tank and the Na2CO3 and NaOH storage tanks.

5. A bipolar membrane electrodialysis device according to claim 4, characterized in that: The ultrafiltration membrane mechanism (6) includes a first membrane shell (601) and a second membrane shell (602), the upper ends of the first membrane shell (601) and the second membrane shell (602) are connected by a connecting pipe (603), a connecting frame (604) is installed between the first membrane shell (601) and the second membrane shell (602), and a supporting frame (605) is installed on the outer wall of the connecting frame (604).

6. A bipolar membrane electrodialysis device according to claim 5, characterized in that: The interior of the first membrane shell (601) is a microfiltration membrane with a pore size of 0.1 μm, and the interior of the second membrane shell (602) is an ultrafiltration membrane with a pore size of 0.02 μm. The lower ends of the first membrane shell (601) and the second membrane shell (602) are both installed with an electrically controlled three-way valve (606), and the branch pipe of the electrically controlled three-way valve (606) is connected to the backwash pipeline.

7. A bipolar membrane electrodialysis device according to claim 6, characterized in that: The bipolar membrane dialysis mechanism (9) comprises a plurality of bipolar membrane dialysis units (903), the plurality of bipolar membrane dialysis units (903) being arranged in series, a circulation input pipe group (901) being installed at the bottom of the bipolar membrane dialysis unit (903), the circulation input pipe group (901) comprising a circulation alkali input pipe, a concentrated salt input pipe, and a circulation acid input pipe, and an output pipe group (902) being installed at the upper end of the bipolar membrane dialysis mechanism (9), the output pipe group (902) comprising a dilute alkali output pipe, a dilute salt water output pipe, and a dilute acid output pipe.

8. A bipolar membrane electrodialysis device according to claim 7, characterized in that: An anode plate (904) is installed on the front end surface of the inner wall of the bipolar membrane dialysis unit (903), and a cathode plate (905) is installed on the rear end surface of the inner wall of the bipolar membrane dialysis unit (903).

9. A bipolar membrane electrodialysis device according to claim 8, characterized in that: A membrane stack (906) arranged in the order of bipolar membrane, acid separator, anion membrane, salt separator, cation membrane and alkali separator is installed between the anode plate (904) and the cathode plate (905).

10. A method for using a bipolar membrane electrodialysis device, implemented based on the bipolar membrane electrodialysis device according to claim 9, characterized in that: The following steps are involved: Step 1: Sodium sulfate high-salt wastewater is used as brine, and the brine is pre-stored in a pre-storage tank (1). An asynchronous motor (105) and a sprocket chain mechanism are used to drive multiple groups of stirring blades (106) located on a bracket (103) at the upper end of the pre-storage tank (1) to rotate, thereby disturbing the tank body and preventing the sodium sulfate high-salt wastewater from accumulating and precipitating. Step 2: The brine is pumped from the first pumping pipeline (2) to the cyclone screening mechanism (3). The cyclone screening mechanism (3) is a conical sieve cavity structure. When the brine enters, under the action of centrifugal force, heavy particles such as mud and sand inside the cyclone move outward and slide down along the inner wall to the separation temporary storage box (304), while the liquid is pumped out through the discharge port (303); Step 3: The brine after the cyclone screening mechanism (3) is pumped into the pH adjustment mechanism (5) through the second pumping pipeline (4), and the pH value of the brine is detected by the pH sensor (502), and the pH of the inlet water is stabilized to the suitable range of 9-11 for the bipolar membrane. If the pH is greater than 11, H2SO4 is added; if the pH is lower than 9, NaOH is added, and Na2CO3 is added for precipitation to remove calcium and magnesium ions; Step 4: The liquid passing through the pH adjustment mechanism (5) enters the ultrafiltration membrane mechanism (6) under the action of the third pumping pipeline (7), and is intercepted by the microfiltration membrane to retain large particles of colloid and suspended matter, and then the ultrafiltration membrane removes small molecular precipitates; Step 5: The liquid filtered by the ultrafiltration membrane mechanism (6) enters the ion exchange treatment mechanism (8) under the action of the fourth pumping pipeline (10); Step 6: The brine after the ion exchange treatment enters the bipolar membrane dialysis mechanism (9) along the circulation input pipe group (901). Both sides of each bipolar membrane dialysis mechanism (9) are positive and negative electrodes. Bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, and alkali separator are arranged in series between the positive and negative electrodes. After the circulating alkali, brine, and circulating acid enter the unit, under the action of the DC electric field, the ions in the input liquid are directed to migrate, so that the bipolar membrane, acid separator, anion membrane, salt separator, cation membrane, and alkali separator are connected in series to form a concentrated alkali chamber, a concentrated salt chamber, and a concentrated acid chamber. The diluted alkali, diluted brine, and diluted acid are respectively discharged from the diluted alkali output pipe, the diluted brine output pipe, and the diluted acid output pipe for subsequent treatment of the diluted alkali, diluted brine, and diluted acid.

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