WO2020077917A1

WO2020077917A1 - A multi-stage zero-emission treatment device for treating high-salt-content waste water

Info

Publication number: WO2020077917A1
Application number: PCT/CN2019/073404
Authority: WO
Inventors: Qiuhong QUAN; Jianfei Zhang; Xifang YUAN; Weiping Shi
Original assignee: Bgt Group Co., Ltd
Priority date: 2018-10-17
Filing date: 2019-01-28
Publication date: 2020-04-23
Also published as: CN111902371A; CN111902371B

Abstract

A multi-stage zero-emission treatment device for treating high-salt-content waste water is provided, which comprises a clarifying pool (1200), a softening pool (910), an ultrafiltration device (920), a weakly acidic cation bed (930), a middle-pressure membrane concentration device (941), a high-pressure membrane concentration device (942), a nanofiltration device (950), a first electro-driven membrane device (961) and a bipolar membrane electrodialysis device (980) in sequence. The bipolar membrane electrodialysis device (980) comprises a plurality of membranes (100) and a dialysis chamber (200), the plurality of membranes (100) including at least two bipolar membranes (110), at least one cation membrane (120), and at least one anion membrane (130), which jointly define at least three compartments; and each membranes (100) is peripherally sealed onto an inner wall of the dialysis chamber (200) through corresponding flexible connecting portions (300) so that the corresponding membranes (100) are allowed to move due to a pressure difference between adjacent compartments, thereby changing the volume of adjacent compartments.

Description

A MULTI-STAGE ZERO-EMISSION TREATMENT DEVICE FOR TREATING HIGH-SALT-CONTENT WASTE WATER

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to the technical field of water treatment, and more particularly relates to a multi-stage zero-emission treatment device for treating high-salt content waste water.

2. Description of the Related Art

A bipolar membrane electrodialysis device is often used in a multi-stage zero-emission treatment device for high-salt-content waste water. A bipolar membrane is a kind of layered membrane, one side of which is a cation exchange layer and the other side of which is an anion exchange layer, wherein a water layer is at the interface between the cation exchange layer and the anion exchange layer. Under influence of the external direct-current electric field, water in the water layer dissociates into H ⁺ and OH ^-, which then permeate the cation exchange layer and the anion exchange layer respectively. The bipolar membrane is a key component of the bipolar electrodialysis (BPED) . BPED is an electrodialysis device that uses the bipolar membrane to dissociate water and uses the permselectivity of anion exchange layer and cation exchange layer to convert salt into acid and alkali.

A Chinese patent publication No. CN2825084Y discloses a concentration electrodialyzer, comprising ion exchange membranes, partition boards, an anode board and a cathode board. Seal lining rings are arranged between the homogeneous phase ion exchange membranes and partition boards, and between the homogeneous phase ion exchange membranes and the anode board and the cathode board. Besides, outlet pipes for electrode solutions and reaction products are inbuilt in the anode and cathode boards to replace the original square milling slot electrode solution outlet channel on the electrode frames. This utility model ensures no inter-leakage exists between the concentrated-water compartments and the fresh-water compartments, and ensures smoother outflow of electrode solutions and reaction products in the electrode compartments, without any dead-zone and with ensured safety in production. This utility model is specifically suitable for concentrating and extracting rare metal from solutions. However, the inter-leakage in this utility model is related to the technical proposal in which membranes are installed in one dialysis cell. If membranes are installed in dialysis cells, when the binding site between the membrane and the dialysis cell is insecure, inter-leakage occurs easily. Therefore, membranes are stacked to form membrane stacks in order to prevent inter-leakage, but leakage due to pressure difference between adjacent compartments is not taken into consideration.

A Chinese patent publication No. CN106630040A discloses a selective bipolar membrane electrodialysis system and the use thereof, comprising electrodialysis membrane stacks, an anode board and a cathode board fixed by clamp plates at two sides of the electrodialysis membrane stacks. Electrodialysis membrane stacks consist of diversified functional membranes superposed alternatively in turn, flow channel partition nets and seal gaskets. Functional membranes include bipolar membranes and multivalent ion permselective membranes. Anion exchange layers of bipolar membranes are facing the anode board, and cation exchange layers of bipolar membranes are facing the cathode board. The selective bipolar membrane electrodialysis system of this invention combines bipolar membrane electrodialysis and selective electrodialysis in one device. When the system is used for desalting saliferous feed liquid and producing acid and alkali, two steps are combined into one operation, and therefore process is simplified, work load is reduced, energy consumption for electrode reaction is decreased, and production efficiency is improved. However, membranes are still fixed in this invention, which cannot solve the leakage problem caused by pressure difference between adjacent compartments.

To sum up, in existing electrodialysis devices, membranes are fixed relative to electrodialysis compartments, in view of which, in the water feeding process, various factors would cause pressure difference between adjacent compartments, resulting in leakage. Leakage refers to, under influence of pressure difference between two sides of a membrane, a solution flows from a high pressure compartment to a low pressure compartment, and as a result, in the leakage process, some ions are entered into compartments unexpected by a producer, thereby reducing efficiency of electrodialysis filtration and impacting purity of final products. One important factor influencing the variation of pressure difference is the flow rate of pumps, which actually is not constant. Voltage fluctuation, frequency fluctuation, component abrasion of pumps such as impeller abration, etc. may cause variation in pressure difference. For variation in pressure difference caused by flow rate fluctuation, it is obtuse and uneconomical to simply monitor pressure with manometer near the water inlet and then adjust the water supply of corresponding supply pumps or outflow rate of corresponding water outlets. Besides, pressure difference may also cause problems such as membrane deformation, damage and/or increased risk of water leakage.

But presently, in this field, technical solutions to solve leakage are to measure pressure difference between adjacent compartments with manometer, then adjust inflow rate or outflow rate of corresponding compartments to reduce pressure difference so as to reduce leakage. As mentioned above, this operation is obtuse and uneconomical, and frequent changes of pump flow rate may easily cause pump damage. Therefore, there is an urgent need in this field to improve the structure of electrodialysis devices, and solve the leakage problem from a new angle.

SUMMARY OF THE INVENTION

In view of the shortcomings of the prior art, the present invention provides a multi-stage zero-emission treatment device for treating high-salt-content waste water, in a bipolar membrane electrodialysis device of which membranes are connected to the dialysis compartment by flexible connecting portions in a movable manner, thereby allowing movement of corresponding membranes under influence of pressure difference between adjacent compartments to change volumes of adjacent compartments, and further quickly reducing pressure difference between adjacent compartments by moving membranes in case of fluctuation in flow rate, reducing leakage caused by pressure difference in an economical and efficient way, without frequently adjusting inflow rate or outflow rate.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a simplified schematic diagram of a preferred embodiment of the present invention;

Fig. 2 is a simplified structural schematic diagram of a preferred embodiment of the electrodialysis compartment comprising an upper and a lower housing of the present invention;

Fig. 3 is a simplified structural schematic diagram of a preferred embodiment of the electrodialysis compartment of the present invention, which is formed by stacking the first seal frames and the second seal frames;

Fig. 4 is a structural schematic diagram of a membrane installed on a first seal frame;

Fig. 5 is an exploded schematic diagram of the structure shown in Fig. 4;

Fig. 6 is a simplified section view of the structure shown in Fig. 4;

Fig. 7 is a simplified section view of two first seal frames stacked together;

Fig. 8 is a simplified schematic diagram of a preferred embodiment of the present invention;

Fig. 9 is a schematic diagram of module connection of partial electrical components of the present invention;

Fig. 10 is a simplified schematic diagram of an alkali compartment of a preferred embodiment of the present invention;

Fig. 11 is a schematic diagram of module connection of a preferred embodiment of the present invention;

Fig. 12 is a simplified schematic diagram of a preferred embodiment of the distributor arranged in a pipe;

Fig. 13 is a simplified section view of a preferred embodiment of the distributor;

Fig. 14 is a simplified front view of a preferred embodiment of the distributor;

Fig. 15 is a schematic isometric diagram of a preferred embodiment of the distributor;

Fig. 16 is a partial schematic diagram of a preferred embodiment of the distributor;

Fig. 17 is a simplified schematic partial section view of a preferred embodiment of the distributor; and

Fig 18 is a simplified schematic diagram of a preferred embodiment of the settling pool.

DETAILED DESCRIPTIONS OF THE INVENTION

The invention is further illustrated below in detail with reference to drawings.

Embodiment 1

The present embodiment discloses a bipolar membrane electrodialysis device. Without causing conflicts or contradictions, the entirety and/or part of preferred modes of other embodiments can be supplement to the present embodiment.

According to a preferred mode, referring to Fig. 1 in which a bipolar membrane electrodialysis device is shown, the bipolar membrane electrodialysis device comprising a plurality of membranes 100 and dialysis compartments 200. The plurality of membranes 100 can comprise at least two bipolar membranes 110, at least one cation membrane 120 and at least one anion membrane 130, which jointly define at least three compartments in the dialysis compartment 200, wherein the at least three compartments includes at least one alkali compartment 210, at least one salt compartment 220, and at least one acid compartment 230. Each of said membrane 100 is peripherally sealed onto an inner wall of the dialysis compartments 200 through corresponding flexible connecting portions 300 so that the corresponding membranes 100 are allowed to move due to a pressure difference between adjacent said compartments, thereby changing the volume of adjacent said compartments. Preferably, an alternative expression of that each said membrane 100 is peripherally sealed onto an inner wall of the dialysis compartments 200 through corresponding flexible connecting portions 300 so that the corresponding membranes 100 are allowed to move due to a pressure difference between adjacent said compartments, thereby changing the volume of adjacent said compartments, is that each of said membrane 100 is peripherally sealed onto an inner wall of the dialysis compartments 200 through corresponding flexible connecting portions 300, wherein the flexible connecting portions 300 are arranged in a manner that the corresponding membranes 100 are allowed to move due to a pressure difference between adjacent said compartments. In this way, the present invention changes the volume to adaptively mitigate pressure difference variation caused by temporary fluctuation of flow rate within a certain range, which reacts rapidly and doesn’t require frequent adjusting of flow rate of pumps, resulting in economical and efficient effects. Preferably, in this invention, to be brief, a membrane 100 can refer to at least one of a bipolar membrane 110, a cation membrane 120 and an anion membrane 130. Preferably, in case of two bipolar membranes 110, one cation membrane 120 and one anion membrane 130, they can be arranged in the sequence of a bipolar membrane 110, a cation membrane 120, an anion membrane 130 and a bipolar membrane 110. A cation membrane 120, an anion membrane 130 and a bipolar membrane 110 can be set as repetition unit to form membrane stacks to improve efficiency. That is, in membrane stacks, membranes can be arranged in the sequence of a bipolar membrane 110, a cation membrane 120, an anion membrane 130, a bipolar membrane 110, a cation membrane 120, an anion membrane 130, a bipolar membrane 110, a cation membrane 120, an anion membrane 130, a bipolar membrane…The material of the flexible connecting portion can be, for example, at least one of nitrile butadiene rubber, butyl rubber, hydrogenated butadiene-acrylonitrile rubber, ethylene propylene rubber, fluororubber, polyurethane rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber and chlorinated polyethylene rubber. Some waste water, after treatment by equipment like settling pools, enters the bipolar membrane electrodialysis device with a quite high temperature, so that without cooling, the flexible connecting portions of the bipolar membrane electrodialysis device can be damaged. Therefore, in this condition, it can be cooled to a certain temperature range, for example, below +40℃, then be fed through the bipolar membrane electrodialysis device. But the cooling is not necessary, for example, when the flexible connecting portions are made of fluororubber, cooling is not necessary, as the operating temperature range of fluororubber is -20℃ to +200℃.

According to a preferred mode, a bipolar membrane electrodialysis device is disclosed, wherein the bipolar membrane electrodialysis device has a plurality of membranes 100 and a dialysis compartment 200. The plurality of membranes 100 can include at least two bipolar membranes 110, at least one cation membrane 120, and at least one anion membrane 130. The at least two bipolar membranes 110, at least one cation membrane 120, and at least one anion membrane 130 jointly define at least three compartments in a dialysis compartment 200, the at least three compartments including at least one alkali compartment 210, at least one salt compartment 220, and at least one acid compartment 230. Each of said bipolar membrane 110, cation membrane 120, anion membrane 130 is peripherally sealed onto an inner wall of the dialysis compartment 200 through corresponding flexible connecting portions 300 so that the corresponding membranes are allowed to move due to the pressure difference between adjacent said compartments, thereby changing the volume of adjacent said compartments. Preferably, a compartment may refer to at least one of an alkali compartment, a salt compartment 220 and an acid compartment. A compartment may also refer to at least one of a positive electrode compartment 240 and a negative electrode compartment 250. Arrangement and location of the positive electrode compartment 240 and the negative electrode compartment 250 are common knowledge in this field and are omitted herein. Fig. 1 is taken as an example to illustrate the principle of the production of acid and alkali by means of the bipolar membrane electrodialysis device. The fixed groups on the membrane body of the cation membrane 120 itself carry negative ions, and therefore reject passage of cations with positive charges and selectively let anions through. The fixed groups on the membrane body of the anion membrane 130 itself carry positive ions, and therefore reject passage of anions with negative charges and selectively let cations through. Saline solution containing salt MX is fed from the water inlet of the salt compartment 220. Under influence of the electric field, cations in the salt compartment 220 move towards the cathode, cation M ⁺ passes through the cation membrane 120 and enters the alkali compartment 210, forming the alkali MOH with OH ^-ionized by the bipolar membrane 110. While anions in the salt compartment 220 move towards the anode, anion X ^-passes through the anion membrane 130 and enters the acid compartment 230, forming acid HX with the H ⁺ ionized by the bipolar membrane 110. Thus, salt in the salt compartment 220 is removed, and converted into corresponding acid HX and alkali MOH. Preferably, a cation membrane 120 is also called cation exchange membrane. An anion membrane 130 is also called anion exchange membrane. Water 800 can be introduced from the water inlet of the alkali compartment 210 and/or the water inlet of the acid compartment.

According to a preferred mode, the dialysis compartment 200 can be a sealed chamber assembled by at least two partial housings, and membranes 100 are sealed inside the dialysis compartment 200 by at least one of adhesion, bolted connection, snap connection and fastening. Each membrane 100 is sealed inside the dialysis compartment 200 assembled by at least two partial housings. For example, the upper housing 200A and the lower housing 200B are shown in Fig. 2. The lower housing 200B can be a hollow chamber with an opening at the top, inside of which there is a mounting groove for installing a membrane 100. When the membrane is installed in place, sealant can be applied to the seam. For ease of inspection and repair, the upper section of the flexible connecting portion 300 can reach out of the hollow chamber. Sealing is realized by compressing the flexible connecting portion 300 after the upper housing 200A is installed on the lower housing 200B.

According to a preferred mode, referring to Fig. 3, Fig. 4 and Fig. 5, at least one part of the dialysis compartment is a chamber formed by stacking a plurality of dismountable first seal frames 200C wherein the adjacent first seal frames are pressed tightly to each other through fasteners. Each of said first seal frames 200C contains at least one membrane 100. Each membrane 100 is sealed onto an inner wall of the first seal frame 200C through at least one independent flexible connecting portion 300. It is perceivable to a person skilled in the art that a second seal frame 200D with an opening at only one side is arranged at two sides of the dialysis compartment 200 to seal both sides of the dialysis compartment 200. The first seal frame 200C and the second seal frame 200D are pressed tightly to form a positive electrode compartment 240 and/or a negative electrode compartment 250.

According to a preferred mode, referring to Fig. 6, the width of the edge portion 300A of the flexible connecting portion 300 connected to the first seal frame 200C is greater than the width of other parts of the flexible connecting portion 300. Preferably, after the flexible connecting portions 300 are installed on the first seal frames 200C and before the first seal frames 200C are stacked together, two ends of an edge portion 300A of each said flexible connecting portion connected to the first seal frame extend out of the first seal frame 200C. After the first seal frames 200C are stacked together, two adjacent said edge portions 300A have their parts extending out of the first seal frames 200C abut against each other so as to provide sealed connection. This preferred mode has at least three beneficial technical effects. Firstly, when installing the flexible connecting portion 300, the parts extending out from two ends are taken as positioning reference, improving installation speed and reducing process error. Especially when the flexible connecting portion 300 is installed inside the first seal frame 200C from outside the first seal frame 200C, adjustment time of the installation personnel can be greatly reduced. Secondly, when the flexible connecting portion 300 installed inside deforms due to the pressure difference, part of the force acting thereon can be delivered to the adjacent flexible connecting portion 300, so that pressure on the connecting elements can be distributed, resulting in that not only consumption of connecting portions such as sealant, bolts or rivets can be reduced, but also leakage problems between adjacent compartments caused by loosening or falling of connecting elements can be reduced. Thirdly, the existing membrane stacks formed by stacking often cause leakage due to weak seal. In this way, it is equivalent to add one more seal leak proof tactfully inside, and the leakage issue in the membrane stacks in the prior art can be significantly improved.

According to a preferred mode, referring to Fig. 6 and Fig. 7, before the first seal frames 200C are stacked together, the parts of the edge portions 300A extending out of the first seal frames 200C are inclined towards the interior of the first seal frames, and in the process of stacking the adjacent two said first seal frames 200C together, the parts of the adjacent edge portions 300A extending out of the first seal frames 200C abut against each other and extend into the interior of the first seal frames 200C, so as to form the sealed connection, and after the sealed connection is formed, a wedge-shaped sealed transverse section A extending into the interior of the first seal frame 200C is formed at the connecting part between two adjacent edge portions300A. Preferably, the parts of the edge portions 300A extending out of the first seal frames 200C are arranged in a manner that the closer it comes to the free end of the two ends of the edge portions 300A, the smaller the thickness is. Thereby at the connecting part between two adjacent edge portions 300A, a wedge-shaped sealed transverse section A extending into the interior of the first seal frame 200C is formed. In this way, at least two beneficial effects can be achieved: firstly, in condition that the compartments are full of fluids, the wedge-shaped sealed transverse section A is pressed by hydraulic pressure at two sides, and the greater the internal hydraulic pressure is, the greater extrusion force the two sides bear, and the tighter they are connected, resulting in water in the compartments being less likely to leak from gaps therebetween; secondly, after the parts of the edge portions 300A extending out of the first seal frames 200C abut against each other, they would not protrude out of the first seal frames 200C, but would be extruded within the gaps between two first seal frames 200C, which would not cause weak adhesion of the first seal frames 200C; thirdly, after the wedge-shaped sealed transverse section A is formed, two edge portions 300A forming the wedge-shaped sealed transverse section A apply a force pointing to the first seal frames 200C on each other, reducing the possibility of the edge portions 300A being peeled off the first seal frames 200C, thereby preventing peel-off.

According to a preferred mode, referring to Fig. 4, Fig. 5 and Fig. 6 again, the flexible connecting portions 300 may comprise a first segment 310 and a second segment 320 that are different in terms of elastic modulus and sealed to each other. The first segment 310 has a first elastic modulus greater than a second elastic modulus of the second segment 320. The first segment 310 is connected to the first seal frame 200C. A part of the second segment 320 is sealed to the first segment 310. And another part of the second segment 320 is sealed to the corresponding membrane 100. This preferred mode achieves at least three beneficial effects: firstly, the greater elastic modulus of the first segment 310 gives it stronger ability to withstand deformation, making it more suited to be used as the connecting part with the first seal frame 200C, so that after it is connected to the first seal frame 200C by sealant, bolt or rivet, its deformation is smaller than that of the second segment 320, causing smaller impact on the connecting portion, reducing the possibility that the connecting portion loosens, and increasing service life of the connecting portion; secondly, the smaller elastic modulus of the second segment 320 makes it respond to pressure difference variation more rapidly; thirdly, smaller elastic modulus causes smaller pressure difference variation with the same deformation levels. Specifically, when fluid at the high pressure side pushes the membrane 100 to move a certain distance, the flexible connecting portion generates a resilience to bring the membrane 100 back to its normal position, wherein this resilience acts on the fluid at the high pressure side, and generates certain pressure difference between the high pressure side and the low pressure side. Therefore, when the deformation levels are the same, the smaller elastic modulus of the second segment 320 causes smaller pressure difference variation, making it harder to cause leakage due to the pressure difference.

According to a preferred mode, referring to Fig. 8, the bipolar membrane electrodialysis device may further comprise a plurality of limit portions. The corresponding limit portions serve to set limit positions that limit movement of the corresponding membrane 100 towards the two compartments adjacent thereto, respectively. For example, the limit portions may be a limit pivot 430 and a plurality of first limit posts 410 and a plurality of second limit posts 420 located at two sides of the membrane 100. In each said compartment a water inlet is located at a first side of the electrodialysis device, so that water flows in the compartments along the same direction. The side where the water outlet of each compartment is located is the second side of the electrodialysis device. The limit pivot 430 is provided at one end of a said corresponding membrane 100 close to the second side, while the first limit posts 410 and the second limit posts 420 are distributed at the two sides of the corresponding membrane 100 for setting limit positions that limit the rotation of the membrane 100 towards the two compartments adjacent to the membrane 100. After the membrane 100 pivots about the limit pivot 430 to one of the limit positions, the membrane 100 abuts against the first limit posts 410 or the second limit posts 420 so as to stop further rotation of the membrane 100 in at least one direction.

According to a preferred mode, referring to Fig. 8 and Fig. 9, when the membrane 100 abuts against the first limit posts 410, a first travel switch 510 may be triggered. When a controller of the bipolar membrane electrodialysis device 600 detects that the first travel switch 510 is triggered, the controller reduces the pressure difference between the two compartments until the membrane 100 leaves the first limit posts 410, by means of at least one of: increasing an input flow of the compartment in which the first travel switch 510 is located, decreasing an output flow of the compartment in which the first travel switch 510 is located, decreasing an input flow of the compartment in which the second travel switch 520 is located, and increasing an output flow of the compartment in which the second travel switch 520 is located. Preferably, when the membrane 100 abuts against the second limit post 420, a second travel switch 520 may be triggered. When the controller of the bipolar membrane electrodialysis device 600 detects that the second travel switch 520 is triggered, the controller reduces the pressure difference between the two compartments until the membrane 100 leaves the second limit posts 420, by means of at least one of: decreasing the input flow of the compartment in which the first travel switch 510 is located, increasing the output flow of the compartment in which the first travel switch 510 is located, increasing the input flow of the compartment in which the second travel switch 520 is located, and decreasing the output flow of the compartment in which the second travel switch 520 is located. Preferably, the first travel switch 510 is mounted on the membrane 100, or is mounted at an end of the first limit post 410, or acts as the first limit post 410 directly. The second travel switch 520 is mounted on the membrane 100, or is mounted at an end of the second limit post 420, or acts as the second limit post 420 directly. By reducing the pressure difference until the corresponding membrane 100 leaves the first limit post 410 or the second limit post, pressure difference can be balanced in a regular control way when pressure difference cannot be balanced by movement of the corresponding membrane 100.

According to a preferred mode, when the controller of the bipolar membrane electrodialysis device detects that the first travel switch is triggered, the controller clocks a duration where the first travel switch remains triggered, and only when the duration during which the first travel switch remains triggered exceeds a first predetermined threshold, the controller reduces the pressure difference between the two compartments until the membrane leaves the first limit posts, by means of at least one of: increasing the input flow of the compartment in which the first travel switch is located, decreasing the output flow of the compartment in which the first travel switch is located, decreasing the input flow of the compartment in which the second travel switch is located, and increasing the output flow of the compartment in which the second travel switch is located. Preferably, when the controller of the bipolar membrane electrodialysis device detects that the second travel switch is triggered, the controller clocks a duration where the second travel switch remains triggered, and only when the duration during which the second travel switch remains triggered exceeds a second predetermined threshold, the controller reduces the pressure difference between the two compartments until the membrane leaves the second limit posts, by means of at least one of: decreasing the input flow of the compartment in which the first travel switch is located, increasing the output flow of the compartment in which the first travel switch is located, increasing the input flow of the compartment in which the second travel switch is located, and decreasing the output flow of the compartment in which the second travel switch is located.

According to a preferred mode, referring to Fig. 10, a plurality of ion exchange resins 700 can be arranged in the alkali compartment 210. The ion exchange resin 700 can be configured as sphere and it is only restricted in terms of motion position by the inner wall of the alkali compartment 210. Preferably, the diameter of the ion exchange resin 700 is in a range of 0.3mm to 2mm. Ion exchange resins 700 include cation exchange resins and anion exchange resins. When the alkali compartment 210 is connected with water flow, the plurality of ion exchange resins 700 scrub inner walls of the alkali compartment 210 to remove at least part of the dirt on the inner walls of the alkali compartment 210 under influence of the water flow. When the volume of the alkali compartment 210 is decreased due to pressure difference variation of the alkali compartment 210, the corresponding membranes 100, which are driven by the flexible connecting portions 300, restore their normal positions and extrude at least part of the ion exchange resins 700 to scrub inner walls of the alkali compartments 210 to remove at least part of the dirt on the inner walls of the alkali compartments 210. Ion exchange resins 700 arranged in the alkali compartments 210 not only further lower electrical resistance of the alkali compartments, making alkali production more economical, but also scrub inner walls of the alkali compartments 210 in two ways, i.e., by water flow impact and movement of membranes 100 extruding sphere ion exchange resins 700, achieving excellent scrubbing effects.

Embodiment 2

The present embodiment may be further improvement and/or complement on embodiment 1 and repeated content is omitted herein. Without causing conflicts or contradictions, the whole or part of the preferred modes of other embodiments can be complement of the present embodiment.

According to a preferred mode, a multi-stage zero-emission treatment device for treating high-salt-content waste water is disclosed, which device, with reference to Fig. 11, may comprise at least one of a waste water tank 810, a clarifying pool 1200, a clarified liquid storage tank 820, a softening pool 910, an ultrafiltration device 920, a weakly acidic cation bed 930, a middle-pressure membrane concentration device 941, a high-pressure membrane concentration device 942, a nanofiltration device 950, a second electro-driven membrane device 962, a first electro-driven membrane device 961, a cryocrystallizer 971, a nitrate crystallizer 972, a sodium chloride crystallizer 973, a bipolar membrane electrodialysis device 980, a waste water lift pump 11, a first clear water pump 12 and a second clear water pump 13. Preferably, the high-salt-content waste water may refer to waste water that contains organics and at least the mass fraction of total dissolved solid is greater than or equal to 1%, preferably 3.5%, and particularly preferably 10%.

Preferably, a multi-stage zero-emission treatment device for treating high-salt-content waste water comprises: a waste water tank 810, for storing high-salt-content waste water to be treated; a clarifying pool 1200 that is connected downstream to the waste water tank 810, for pre-treating the high-salt-content waste water to remove impurity particles, which can obtain the high-salt-content waste water in the waste water tank 810 by a waste water lift pump 11; a clarified liquid storage tank 820 that is connected downstream to the clarifying pool 1200, for storing clarified liquid treated by the clarifying pool 1200, which can obtain the clarified liquid treated by the clarifying pool by a first clear water pump 12; a softening pool 910 that is connected downstream to the clarified liquid storage tank 820, for primary softening to reduce hardness of the liquid, which can obtain the clarified liquid stored in the clarified storage tank 820 by a second clear water pump 13; an ultrafiltration device 920 that is connected downstream to the softening pool 910, for filtration and concentration of the liquid; a weakly acidic cation bed 930 that is connected downstream to the ultrafiltration device 920, for secondary softening to further reduce hardness of the liquid, so as to ensure stable operation of devices downstream; a middle-pressure membrane concentration device 941 that is connected downstream to the weakly acidic cation bed 930, for concentrating the liquid, and clear liquid of the middle-pressure membrane concentration device 941 can be delivered to a product water pipe 840 for collecting fresh water; a high-pressure membrane concentration device 942 that is connected downstream to the middle-pressure membrane concentration device 941, for re-concentrating the concentrated liquid of the middle-pressure membrane concentration device 941, the clear liquid of the high-pressure membrane concentration device 942 can be delivered to the product water pipe 840; a nanofiltration device 950 that is connected downstream to the high-pressure membrane concentration device 942, for filtering the concentrated liquid of the high-pressure membrane concentration device 942; a second electro-driven membrane device 962 that is connected downstream to the nanofiltration device 950, for concentrating trapped fluid of the nanofiltration device 950, and fresh water of the second electro-driven membrane device 962 can be delivered to the product water pipe 840, concentrated water of the second electro-driven membrane device 962 can be delivered to a cryocrystallizer 971; a first electro-driven membrane device 961 that is connected downstream to the nanofiltration device 950, for concentrating permeated fluid of the nanofiltration device 950, and fresh water of the first electro-driven membrane device 961 can be delivered to the salt compartment of the bipolar membrane electrodialysis device; a cryocrystallizer 971 that is connected downstream to the second electro-driven membrane device 962, for freeze crystallization of the concentrated water of the second electro-driven membrane device 962, and the sodium sulfate decahydrate mother liquid separated out in the cryocrystallizer 971 is delivered to a nitrate crystallizer 972, clear liquid of the cryocrystallizer 971 is delivered to a sodium chloride crystallizer 973; a nitrate crystallizer 972 that is connected downstream to the cryocrystallizer 971, for evaporation and concentration of the sodium sulfate decahydrate mother liquid to obtain sodium sulfate; a sodium chloride crystallizer 973 that is connected downstream of the cryocrystallizer 971, for evaporation and concentration of the clear liquid of the cryocrystallizer 971 to obtain sodium chloride; and/or a bipolar membrane electrodialysis device 980, for producing acid and/or alkali from salt-containing fluid entering its salt compartment. The weakly acidic cation bed 930 utilizes the strong ion exchange capacity of the weakly acidic cation exchange resin. Preferably, the weakly acidic cation bed uses a carboxylic cation resin. The carboxylic cation resin, like organic acids, dissociates weakly in water, and is weakly acidic, which can only dissociate in medium that is close to neutral and alkaline to present its ion exchange function. The high-salt-content waste water undergoes multi-stage treatment of the clarifying pool 1200, the softening pool 910, the ultrafiltration device 920, the weakly acidic cation bed 930, the middle-pressure membrane concentration device 941, the high-pressure membrane concentration device 942, the nanofiltration device 950, the second electro-driven membrane device 962, the first electro-driven membrane device 961, the cryocrystallizer 971, the nitrate crystallizer 972, the sodium chloride crystallizer 973 and/or the bipolar membrane electrodialysis device 980 of the present invention, thereby achieving zero-emission.

According to a preferred mode, a multi-stage zero-emission treatment device for treating high-salt-content waste water comprises at least one of: a clarifying pool 1200, a softening pool 910 that is connected downstream to the clarifying pool 1200, an ultrafiltration device 920 that is connected downstream to the softening pool 910, a weakly acidic cation bed 930 that is connected downstream to the ultrafiltration device 920, a middle-pressure membrane concentration device 941 that is connected downstream to the weakly acidic cation bed 930, a high-pressure membrane concentration device 942 that is connected downstream to the middle-pressure membrane concentration device 941, a nanofiltration device 950 that is connected downstream to the high-pressure membrane concentration device 942, a first electro-driven membrane device 961 that is connected downstream to the nanofiltration device 950 and serves to concentrate a permeated liquid coming from the nanofiltration device 950, and a bipolar membrane electrodialysis device 980 that is connected downstream to the first electro-driven membrane device 961. The bipolar membrane electrodialysis device 980 serves to treat a concentrated water coming from the first electro-driven membrane device 961 so as to produce an acid and/or an alkali. The concentrated water flowing out of the first electro-driven membrane device 961 can be delivered to the salt compartment of the bipolar membrane electrodialysis device 980. Preferably, the nanofiltration device 950 is used to separate the monovalent salt from the bivalent salt. The nanofiltration device 950 is permeable to the monovalent salt and retains bivalent salt. Preferably, the bipolar membrane electrodialysis device 980 has concentration function during electrodialysis. Preferably, the recovering rate of the bipolar membrane electrodialysis device 980 is around 90%, the desalting rate is higher than 90%, and the bipolar membrane electrodialysis device 980 has excellent concentration function. While the salt rate of the waste water increases at the concentrated water side, desalting is well performed at the fresh water side, thereby better addressing the problem of waste water treatment. Preferably, the multi-stage zero-emission treatment device for treating high-salt-content waste water comprises: a clarifying pool, a softening pool, a high-intensity membrane device or an ultrafiltration device, a weakly acidic cation bed, a middle-pressure membrane concentration device, a high-pressure membrane concentration device, a nanofiltration device, a first electro-driven membrane device or a bipolar membrane electrodialysis device, a multi-functional evaporator, a cryocrystallizer, a nitrate crystallizer, a sodium chloride crystallizer and a miscellaneous salt crystallizer, wherein the clarifying pool, the softening pool and the weakly acidic cation bed reduce hardness and turbidity of waste water, the high-intensity membrane or the ultrafiltration device removes suspended solids and organics, the nanofiltration device separates the monovalent salt from the bivalent salt, and the middle-pressure membrane concentration device, the high-pressure membrane concentration device, the electro-driven membrane device and the multi-functional evaporator have the function of concentration, the cryocrystallizer, the nitrate crystallizer, the sodium chloride crystallizer and the miscellaneous salt crystallizer crystallize salt, turning the waste water to a resource. High-salt-content waste water undergoes multi-stage treatment by these devices, realizing zero-emission.

Embodiment 3

The present embodiment is further improvement and/or supplement based on Embodiment 1 and/or Embodiment 2, and the repeated description is omitted herein. The present embodiment discloses a clarifying pool 1200, and without causing any conflicts or contradictions, the whole or part of the preferred modes of other embodiments can be complement of the present embodiment.

According to a preferred mode, referring to Fig. 12 and Fig. 18, a clarifying pool 1200 comprises a pool body 1210, at least one water inlet pipe 1220 and a distributor 1100. The distributor 1100, in work condition, is arranged in the pipeline 1000 of the water inlet pipe 1220. Referring to Fig. 13 and Fig. 14, a hollow chamber 1170 for containing liquid agents can be arranged inside of the distributor 1100. A plurality of distributing holes 1110 for eluting of the liquid agents in the hollow chamber 1170 can be arranged on the housing of the distributor 1100. A reflecting board 1120 can be arranged adjacent to at least part distributing holes 1110 of the plurality of distributing holes 1110. The corresponding reflecting board 1120 can be arranged in such a way that at least portions of the liquid agents flowing out of the corresponding distributing holes 1110 are rush by fluids in the pipeline 1000 to the reflecting board 1120, then under impact of the reflecting board 1120, are reflected toward outside of the region where the reflecting board 1120 is located. Therefore, the distributor 1100 can take advantage of the flowing fluid to mix the liquid agents with the fluid in the pipeline 1000. The distributor 1100 can serve to add corresponding liquid agents to the clarifying pool. For example, the liquid agent in the distributor 1100 may be a coagulating agent or a flocculating agent. Preferably, the liquid agent in the distributor 1100 is a coagulating agent. If the coagulating agent is in solid state, the solid coagulating agent can be put into a vitriol dissolving pool before use, running water or pure water is added and stirred to fully dissolve the coagulating agent, then the solution is diluted with water to desired concentration and used for coagulation. Using the distributor 1100 of the present invention to add coagulating agents can significantly reduce stirring time of the stirrer and improve efficiency of the coagulating stage after the coagulating agent is added into the clarifying pool, as the coagulating agent and raw water are mixed more sufficiently in the pipeline than direct injection. It can be anticipated that the liquid agent in the distributor of the present invention can be replaced by a gaseous agent, for conditions that requires addition of gaseous agents into corresponding liquids or gases. For example, in a treatment device for waste gas requiring denitration, ammonia gas is added into the pipeline of the waste gas, to fully mix the ammonia gas and the waste gas and to fully react with oxynitride in the waste gas. When the distributor is used with gaseous agents, a person skilled in the art can adjust parameters such as component shape and size of the distributor according to practical needs to improve mix efficiency of the gaseous agents.

According to a preferred mode, a distributor 1100 is disclosed, which distributor 1100 is hollow to contain liquid agent, wherein a reflecting board 1120 is arranged outside the distributing holes 1110 of the distributor 1100, which reflecting board 1120 is such arranged that at least one part of the liquid agent from the corresponding distributing hole 1100 is pushed to the reflecting board 1120 by a liquid in the pipeline 1000 and then pushed out by the reflecting board 1120 to spread around.

According to a preferred mode, at least part of the plurality of distributing holes are equipped with one-way valves. The one-way valves may allow passage from the hollow chamber 1170 to the outside of the distributor 1100. Liquid agents flow out of the distributing holes 1100 through one-way valves, reducing the possibility that liquid in the pipeline contaminates the liquid agents and jams the distributing holes 1100.

According to a preferred mode, the reflecting board 1120 is arranged on the housing of the distributor 1100, and in a first projection plane, the projection of the reflecting board 1120 and the projection of the housing of the distributor 1100 do not overlap or only partially overlap. The case that there’s no overlap could be caused by the reflecting board 1120 that is connected to the edge of the housing of the distributor 1100. The more the overlap is, the partial liquid reflected by the housing and the partial liquid reflected by the reflecting board offset in terms of energy, so that the smaller the overlap is, the stronger the reflecting board 1120 reflects the liquid, and the better the mixing effect is. The area of the overlap is smaller or equals to half of the area of the projection of the reflecting board 1120, preferably, the area of the overlap is smaller or equals to one third of the area of the projection of the reflecting board 1120. The first projection plane is a plane that is perpendicular to the overall flowing direction of the fluid where the distributor is located. For a straight pipe with no branches, taking Fig. 12 as an example, the fluid inside has two overall flowing directions, one to the left and the other to the right. The reflecting board 1120 can be arranged integrated with the housing of the distributor 1100, or the reflecting board 1120 can be arranged on the housing of the distributor 1100 by at least one of snap connection, bonding, welding and fastener connections.

According to a preferred mode, the distributor 1100 is fixed in the pipeline 1000, and the distributor 1100 cannot rotate itself. For example, the distributor 1100 is supported by a rigid component and is connected to the wall of the pipeline 1000. Also, for example, the size of the distributor 1100 is set to match the inner diameter of the pipeline 1000, and the distributor 1100 is arranged at a predetermined position and then is bonded inside the pipeline 1000 by bonding. Also, for example, a slot is arranged at the outlet region of the pipeline 1100, and the distributor 1100 is installed inside the pipeline 1000 by snap connection. There are other prior arts for installing a component inside the pipeline 1000 in this technical field, which can also be applied in the present invention by a person skilled in the art, for fixing the distributor 1100 in the pipeline 1000.

According to a preferred mode, the distributor 1100 can be pivotally arranged inside the pipeline 1000. For example, the distributor 1100 can be pivotally arranged inside the pipeline 1000 by a first rotation axis 1131. The first rotation axis 1131 and the shape of the distributor 1100 can be arranged in such a way that fluid in the pipeline 1000, when flowing, drives the distributor 1100 to rotate along the first rotation axis 1131. Specifically, the distributor 1100 is fixedly connected to the first rotation axis 1131. The first rotation axis 1131 can be connected to an installation panel 1140 by bearing. The installation panel 1140 can be connected to the pipeline 1000 by at least one of snap connection, screw connection, bonding and welding connection, so as to pivotally arrange the distributor inside the pipeline 1000. Also, for example, the distributor 1100 can be arranged pivotally in a through-hole of the installation panel 1140 as a whole. A channel rail can be arranged in the through hole of the installation panel 1140 so that the distributor 1100 rotates along the channel rail.

Preferably, the first rotation axis 1131 and the shape of the distributor 1100 can be configured in such a way that fluid in the pipeline 1000, when flowing, drives the distributor 1100 to rotate along the first rotation axis 1131, by setting a part of the distributor 1100 as a plurality of blades 1150. The plurality of blades 1150 drive the common first rotation axis 1131 to rotate. Preferably, the plurality of blades 1150 comprise 2, 3, 4, 5, 6, 7 or 8 blades. Preferably, the forms of the blades 1150 are not limited to the forms shown in figures, which, for example, can also be the form of a screw propeller and/or a fan blade. Particularly preferably, the plurality of blades 1150 comprise 6 or 8 blades, to cover a majority of the area of the cross section of the pipeline 1000. Preferably, the blades 1150 can be used for sealing the end plugs 1151 at the free ends of the blades 1150. The end plugs 1151 can be removably connected to the blades 1150, for example, by at least one of the removable connections of snap connection, riveting, screw and fastener. Setting the removable end plugs 1151 facilitates maintenance of the distributor when there is blocking inside the blade 1150 or in other situations that require recondition or change of one-way valves and so on.

According to a preferred mode, the plurality of distributing holes 1110 are arranged on the latter slope in the rotation direction of each blade 1150. Particularly, the outlet direction of each distributing hole 1110 is such arranged that when the distributor 1100 is rotating clockwise, at least one component of the ejecting direction of the liquid agent from the distributing hole is pointing to the reflecting board 1120. Besides, with such arrangement, the ejected liquid agent provides partial rotation impetus for the distributor.

According to a preferred mode, flowing liquid in the pipeline acts on the slopes of the blades and pushes the distributor to rotate, and the distributing holes 1110 form an elliptical or quasi elliptical ejecting orifice on the slope, which is arranged in the manner that the long axis of the ellipse is along the rotation direction, so that when the liquid agent ejects from the distributing holes 1100, it has at least one component pointing to the reflecting board 1120. The ellipse shape is not easy to block, and at the same time it takes the choice of ejecting direction pointing to the reflecting board into consideration; besides, inaccuracy in the hole cutting process better facilitates sufficient mixing. Preferably, at least one of the components pointing to the reflecting board 1120 coordinates with the posture of the reflecting board 1120, especially it is orthogonal to the surface of the reflecting board 1120. Preferably, in states that the distributor is not rotated and/or is rotated, ejecting pressure of the distributor is such set that the ejected liquid agent can at least reach or go beyond the free end of the reflecting board 1120. The free end of the reflecting board 1120 refers to the distal end away from the blades. When the liquid agent ejects from the ejecting orifice on the slope, a part of the liquid agent ejects to the free end of the reflecting board, which, during movement, is impacted by the fluid in the pipeline 1000 to the reflecting board and is then reflected. A part of the liquid agent is impacted near the blades by the fluid to the slopes of the blades, part of which flows along the slopes to the reflecting board and is then reflected.

According to a preferred mode, the side of the reflecting board 1120 that is close to the distributing holes 1110 is the reflecting side 1120A. The reflecting side 1120A can be arranged in such a way that the fluid acting on it has the tendency to be reflected to a specific area. Reflecting to a specific area refers to that the fluid is not reflected dispersedly around, but is reflected towards a predetermined area, when guided by the reflecting side 1120A. In this way, the reflecting energy gathers towards the direction of the specific area, and the larger the radiating area of the reflection is, and the better mixing effects are obtained. For example, the specific direction can be radial direction, circumferential direction or specific inclining direction.

According to a preferred mode, referring to Fig. 15, the reflecting side 1120A can be arranged in such a way that the fluid acting on it has the tendency to be reflected to a specific area due to obliquely setting of the reflecting side 1120A in a plane state, so that the fluid acting on it has a tendency to be reflected towards the wall of the pipeline 1000 and/or opposite to the rotation direction. Preferably, the inclination angle can be greater than 0° and smaller than or equal to 50°, preferably 5°, 10°, 20° and 30°, wherein the inclination angle is the included angle between the plane of the reflecting side 1120A in a planar state and a plane perpendicular to the overall flowing direction of the fluid in the pipeline.

According to a preferred mode, referring to Fig. 16, the reflecting side 1120A can be arranged in such a way that the fluid acting on it has the tendency to be reflected to a specific area, due to setting of at least one part of the reflecting side 1120A as concave. The form of the concave can be arranged in such a way that the fluid acting on it has a tendency to be reflected toward the wall of the pipeline 1000 and/or opposite to the rotation direction. Preferably, the concave can be a curved surface, or is formed by a plurality of planes.

According to a preferred mode, referring to Fig. 17, the reflecting board 1120 may be a scalable structure formed by at least two expansion plates 1121, and the adjacent two expansion plates of the at least two expansion plates 1121 are movable against each other and are seal connected to each other, wherein a hydraulic chamber 1122 is at the middle of the at least two expansion plates 1121, which hydraulic chamber 1122 is connected to the hollow chamber in liquid path by drainage holes 1190 arranged adjacent to the corresponding distributing holes 1110. The drainage holes 1190 are arranged adjacent to the corresponding distributing holes 1110 so that the internal pressure of the corresponding reflecting board 1120 is consistent with the internal pressure of the distributing holes 1110 as much as possible. Preferably, the at least two expansion plates 1121 are coated with an elastic rubber element 1123, which is arranged in such a way that it can pull the at least two expansion plates 1121 in the direction opposite to their expansion direction when the pressurized liquid agent is not added to the hollow chamber; and/or a return spring 1124 is arranged in the hydraulic chamber 1122 of the at least two expansion plates 1121, which return spring 1124 is arranged in such a way that it can pull the at least two expansion plates 1121 in the direction opposite to their expansion direction when the pressurized liquid agent is not added to the hollow chamber. In this circumstance, the expansion length of the reflecting board 1120 depends on the pressure at the corresponding position of the corresponding distributing hole. For example, the distributing hole closer to the middle has greater ejecting pressure, and the corresponding reflecting board expands longer, so that the liquid agent ejected far away can be well reflected by the reflecting board, reducing the possibility that the liquid agent is ejected beyond the reflecting board and flows downstream directly, which is equivalent to that each reflecting board has a variable length, and can adapt to each distributing hole 1110 with different ejecting pressure.

According to a preferred mode, the axis of the corresponding distributing hole 1110 and the expansion direction of the corresponding reflecting board 1120 are arranged to form an acute angle. In this circumstance, each row of reflecting board 1120 can function as wiper comb, further improving mixing effects of the liquid agent. Besides, when the reflecting board 1120 expands to its limit position, the free end of the reflecting board 1120 is parallel to or exceeds the axis of the distributing hole 1110. The free end of the reflecting board 1120 exceeding the axis of the distributing hole 1110 means that the free end and the non-free end of the reflecting board 1120 are located at two sides of the axis of the corresponding distributing hole, respectively. In this way, even if the ejecting pressure is very high, the liquid agent ejected from the corresponding distributing hole 1110 will be ejected to the reflecting board 1120 at the position it leaves the distributing hole 1110, and then at least be partially reflected away from the reflecting board, and at least a part of it will be reflected upstream of the position where the reflecting board is located, which then flows back to the position of the reflecting board and is stirred by the reflecting board, and then flows to the downstream stirrer and be stirred and mixed by the downstream stirrer, thus improving mixing effects.

According to a preferred mode, the distributor 1100 further comprises a projecting stirring part 1160. The stirring part can be arranged in such a way that during rotation of the distributor 1100, the stirring part can stir the fluid in the pipeline 1000. The position of the stirring part 1160 can be arranged in such a way that it only stirs the fluid after the fluid flows through the cross section where the reflecting board 1120 is located. In this way, the stirrer would not cause whirl before reflection, which impacts reflection of the liquid agent, and after the liquid agent is reflected to the fluid by the reflecting board and undergoes one round of mixing, it is mixed for the second time by stirring. In addition, a corresponding whirl is formed in the fluid when stirring, and the condition of mixing is improved. Preferably, the stirring part 1160 can be pivotally connected to the housing of the distributor 1100. Stirring blades 1161 are arranged on the stirring part 1160. The stirring blades 1161 can be arranged in such a way that when the stirring part 1160 and/or the distributor move against the fluid, the stirring blades 1161 are driven to rotate by the fluid. As a result, the stirring part 1160 can produce whirls in the fluid better, improving mixing effects. Preferably, in the case that at least two distributing holes 1110 are arranged on a single blade 1150, at least one stirring blade 1160 is arranged between each two distributing holes 1110.

According to a preferred mode, the stirring part 1160 is pivotally connected to the housing of the distributor 1100 by a second rotation axis 1132, which second rotation axis 1132, at least when the distributor 1100 is rotated, is arranged at an acute angle with respect to a first plane perpendicular to the first rotation axis 1131, and which second rotation axis 1132 inclines opposite to the rotation direction of the distributor 1100. The blades 1150 of the distributor 1100 drive the distributor 1100 to rotate, while the fluid pushing the blades 1150 produces a great whirl opposite to the rotation direction, and therefore, setting the second rotation axis 1131 as inclining opposite to the rotation direction of the distributor 1100 facilitates formation of small whirls in great whirls, improving mixing effects. Preferably, the second rotation axis 1132 can be obliquely arranged to always form a fixed angle with respect to the first plane. For example, the second rotation axis 1132 is rigidly connected to the housing of the distributor, so that the second rotation axis 1132 and the first plane are arranged to always form an acute angle. Rigid connection can be at least one of welding, snap, screwing and riveting connections. Or the second rotation axis 1132 can be obliquely arranged to form an acute angle with respect to the first plane, only when the distributor 1100 is rotated. For example, the second rotation axis 1132 may comprise a rigid axis section and a flexible axis section, wherein the rigid axis section and the flexible axis section are connected by bonding adhesion, and the rigid axis section is used for pivotally installing the stirring part 1160, while the flexible axis section is fixedly connected to the housing of the distributor 1100, so that the second rotation axis 1132 inclines opposite to the rotation direction of the distributor 1100 when the distributor 1100 rotates. The fixed connection herein can be bonding, screwing or snap connection. For secure connection, a corresponding flange plate or flange can be arranged on the part where the flexible axis and the housing of the distributor 1100 connect. For another example, the second rotation axis 1132 is a rigid axis, while the second rotation axis 1132 is hinged to the housing of the distributor 1100, so that the second rotation axis 1132 inclines opposite to the rotation direction of the distributor 1100 when the distributor 1100 rotates. The second rotation axis 1132 is hinged to the housing of the distributor 1100 by at least one of loose leaf hinge, hook joint and spherical hinge. Particularly preferably, the second rotation axis 1132 is hinged to the housing of the distributor 1100 by spherical hinge, so as to dynamically adjust inclination direction of the second rotation axis 1132 during rotation of the distributor 1100. The inclination direction of the second rotation axis 1132 matches the rotation speed of the distributor 1100 and the direction of the great whirl produced by the blades 1150, so that the stirring blades 1161 follow the direction of the great whirl and produce small whirls therein, thereby improving mixing effects.

It should be noted that the above-described embodiments are exemplary, and a person skilled in the art may come up with various solutions inspired by the disclosure of the present invention, which belong to the disclosure of the present invention and fall in the protection scope of the present invention. A person skilled in the art shall understand that the specification and the figures are illustrative and do not constitute limitations of the claims. The protection scope of the present invention is defined by the claims and the equivalents thereof.

Claims

A multi-stage zero-emission treatment device for treating high-salt-content waste water, characterized in that the device comprises:

a clarifying pool (1200) , a softening pool (910) that is connected downstream to the clarifying pool (1200) , an ultrafiltration device (920) that is connected downstream to the softening pool (910) , a weakly acidic cation bed (930) that is connected downstream to the ultrafiltration device (920) , a middle-pressure membrane concentration device (941) that is connected downstream to the weakly acidic cation bed (930) , a high-pressure membrane concentration device (942) that is connected downstream to the middle-pressure membrane concentration device (941) , a nanofiltration device (950) that is connected downstream to the high-pressure membrane concentration device (942) , a first electro-driven membrane device (961) that is connected downstream to the nanofiltration device (950) and serves to concentrate a permeated liquid coming from the nanofiltration device (950) , and a bipolar membrane electrodialysis device (980) that is connected downstream to the first electro-driven membrane device (961) ;

wherein, the bipolar membrane electrodialysis device (980) serves to treat a concentrated water coming from the first electro-driven membrane device (961) so as to produce an acid and/or an alkali;

the bipolar membrane electrodialysis device (980) comprises a plurality of membranes (100) and a dialysis compartment (200) , the plurality of membranes (100) including at least two bipolar membranes (110) , at least one cation membrane (120) , and at least one anion membrane (130) , which jointly define at least three compartments in the dialysis compartment (200) , wherein the at least three compartments include at least one alkali compartment (210) , at least one salt compartment (220) , and at least one acid compartment (230) ; and

each said membrane (100) is peripherally sealed onto an inner wall of the dialysis compartments (200) through corresponding flexible connecting portions (300) so that the corresponding membranes (100) are allowed to move due to a pressure difference between adjacent said compartments, thereby changing the volume of adjacent said compartments.
A multi-stage zero-emission treatment device for treating high-salt-content waste water, characterized in that the device comprises a bipolar membrane electrodialysis device, which has a plurality of membranes and a dialysis compartment, the plurality of membranes including at least two bipolar membranes, at least one cation membrane, and at least one anion membrane, which jointly define at least three compartments in a dialysis compartment, wherein the at least three compartments include at least one alkali compartment, at least one salt compartment, and at least one acid compartment; and wherein each said membrane is peripherally sealed onto an inner wall of the dialysis compartment

through corresponding flexible connecting portions so that the corresponding membranes are allowed to move due to the pressure difference between adjacent said compartments, thereby changing the volume of adjacent said compartments.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein at least one part of the dialysis compartment is a chamber formed by stacking a plurality of dismountable first seal frames in which the adjacent first seal frames are pressed tightly to each other through fasteners, and each said first seal frame contains a membrane, which is sealed onto an inner wall of the first seal frame through at least one independent flexible connecting portion.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein after the flexible connecting portions are installed on the first seal frames and before the first seal frames are stacked together, two ends of an edge portion of each said flexible connecting portion connected to the first seal frame extend out of the first seal frame, and

after the first seal frames are stacked together, two adjacent said edge portions have their parts extending out of the first seal frames abut against each other so as to provide sealed connection.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein before the first seal frames are stacked together, the parts of the edge portions extending out of the first seal frames are inclined towards the interior of the first seal frames, and in the process of stacking the adjacent two said first seal frames together, the parts of the adjacent edge portions extending out of the first seal frames abut against each other and extend into the interior of the first seal frames, so as to form the sealed connection, and after the sealed connection is formed, a wedge-shaped sealed transverse section extending into the interior of the first seal frame is formed at the connecting part between two adjacent edge portions.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein the flexible connecting portion at least comprises a first segment and a second segment that are different in terms of elastic modulus and sealed to each other, the first segment having a first elastic modulus greater than a second elastic modulus of the second segment, the first segment being connected to the first seal frame, a part of the second segment being sealed to the first segment, and another part of the second segment being sealed to the corresponding membrane.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein the bipolar membrane electrodialysis device further comprises a plurality of limit portions, the corresponding limit portions serving to set limit positions that limit movement of the corresponding membrane towards the two compartments adjacent thereto, respectively.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein the limit portions are a limit pivot and a plurality of first limit posts and a plurality of second limit posts located at two sides of the membrane;

wherein in each said compartment a water inlet is located at a first side of the electrodialysis device so that water flows in the compartments along the same direction, and the side where the water outlet of each compartment is located is the second side of the electrodialysis device;

the limit pivot is provided at one end of a said corresponding membrane close to the second side, the first limit posts and the second limit posts being distributed at the two sides of the corresponding membrane for setting limit positions that limit the rotation of the membrane toward the two compartments adjacent to the membrane; and

after the membrane pivots on the limit pivot to one of the limit positions, the membrane abuts against the first limit posts or the second limit posts so as to stop further rotation of the membrane in at least one direction.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein when the membrane abuts against the first limit posts, a first travel switch is triggered, and when a controller of the bipolar membrane electrodialysis device detects that the first travel switch is triggered, the controller reduces the pressure difference between the two compartments until the membrane leaves the first limit posts by means of at least one of: increasing an input flow of the compartment in which the first travel switch is located, decreasing an output flow of the compartment in which the first travel switch is located, decreasing an input flow of the compartment in which the second travel switch is located, and increasing an output flow of the compartment in which the second travel switch is located; and/or

when the membrane abuts against the second limit post, a second travel switch is triggered, and when the controller of the bipolar membrane electrodialysis device detects that the second travel switch is triggered, the controller reduces the pressure difference between the two compartments until the membrane leaves the second limit posts by means of at least one of: decreasing the input flow of the compartment in which the first travel switch is located, increasing the output flow of the compartment in which the first travel switch is located, increasing the input flow of the compartment in which the second travel switch is located, and decreasing the output flow of the compartment in which the second travel switch is located.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein the first travel switch is mounted on the membrane, or is mounted at an end of the first limit post, or acts as the first limit post directly; and/or

the second travel switch is mounted on the membrane, or is mounted at an end of the second limit post, or acts as the second limit post directly.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein when the controller of the bipolar membrane electrodialysis device detects that the first travel switch is triggered, the controller clocks a duration during which the first travel switch remains triggered, and only when the duration during which the first travel switch remains triggered exceeds a first predetermined threshold, the controller reduces the pressure difference between the two compartments until the membrane leaves the first limit posts by means of at least one of: increasing the input flow of the compartment in which the first travel switch is located, decreasing the output flow of the compartment in which the first travel switch is located, decreasing the input flow of the compartment in which the second travel switch is located, and increasing the output flow of the compartment in which the second travel switch is located; and/or

when the controller of the bipolar membrane electrodialysis device detects that the second travel switch is triggered, the controller clocks a duration during which the second travel switch remains triggered, and only when the duration during which the second travel switch remains triggered exceeds a second predetermined threshold, the controller reduces the pressure difference between the two compartments until the membrane leaves the second limit posts by means of at least one of: decreasing the input flow of the compartment in which the first travel switch is located, increasing the output flow of the compartment in which the first travel switch is located, increasing the input flow of the compartment in which the second travel switch is located, and decreasing the output flow of the compartment in which the second travel switch is located.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein the clarifying pool of the multi-stage zero-emission treatment device comprises a pool body, at least one inlet pipe, and a distributor, the distributor being installed in the pipeline of the inlet pipe and containing therein a liquid agent which is a coagulating agent or a flocculating agent;

wherein the distributor when working is located inside the pipeline and the distributor defines therein a hollow chamber for accommodating the liquid agent, the distributor being provided with a plurality of distributing holes for distributing the liquid agent from the hollow chamber, and wherein a reflecting board is equipped near at least a part of the plural distributing holes, the reflecting board being such installed that at least one part of the liquid agent from the corresponding distributing hole is pushed to the reflecting board by a liquid in the pipeline and then pushed out by the reflecting board to flow into areas other than an area in which the reflecting board is located, thereby allowing the liquid agent and the liquid to be mixed using flow of the liquid in the pipeline.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein the side of the reflecting board that is close to the distributing hole is an acting surface, and the acting surface is configured to redirect the liquid hitting thereon to particular said areas;

wherein the acting surface is configured to redirect the liquid hitting thereon to particular said areas by at least one of:

the acting surface which is a flat surface being arranged inclined, so that the liquid hitting thereon is redirected to a wall of the pipeline; and

at least one part of the acting surface being arranged as concave and the concave part redirecting the liquid hitting thereon toward the wall of the pipeline.
The multi-stage zero-emission treatment device of any of the preceding claims, wherein the reflecting board is an extendable structure formed by at least two extension boards, each two said adjacent extension boards of the at least two extension boards being movable with respect to each other and sealed to each other, wherein a hydraulic chamber is formed between the at least two extension boards, and is liquid-communicated with the hollow chamber through a draining hole close to a corresponding said distributing hole.
A bipolar membrane electrodialysis device, comprising a plurality of membranes and a dialysis compartment, wherein the plurality of membranes include at least two bipolar membranes, at least one cation membrane, and at least one anion membrane, which jointly define at least three compartments in the dialysis compartment, the at least three compartments including at least one alkali compartment, at least one salt compartment, and at least one acid compartment;

wherein each said membrane is peripherally sealed onto an inner wall of the dialysis compartment through corresponding flexible connecting portions so that the corresponding membranes are allowed to move due to a pressure difference between adjacent said compartments, thereby changing the volume of adjacent said compartments.