Resource-based treatment processes and systems for wastewater with high salinity and high organic content

Abstract

This invention provides a resource-based treatment process and system for wastewater with high salinity and high organic content. Based on this invention, the treatment of wastewater with high salinity and high organic content can significantly improve salt recovery rate and reduce the generation of impurities. The process includes the following steps: 1) feeding the wastewater into a softening coagulation sedimentation unit for coagulation sedimentation to obtain product water I; 2) feeding product water I into an ultrafiltration resin unit for ultrafiltration and resin adsorption sequentially to obtain product water II; 3) feeding product water II into an organic matter retention unit to obtain a saline stream containing separated organic matter, which becomes product water III; 4) feeding product water III into an advanced oxidation unit to obtain product water IV; 5) feeding product water IV as the raw solution to be treated into a bipolar membrane electrodialysis unit for electrodialysis to obtain acid solution, alkali solution, and desalinated fresh water; 6) feeding the desalinated fresh water into a membrane concentration unit.

Description

Technical Field

[0001] This invention relates to a resource-based treatment technology for wastewater with high salinity and high organic content, and particularly to a resource-based treatment process and system for wastewater with high salinity and high organic content. Background Technology

[0002] Zero-discharge treatment of industrial wastewater generally involves five steps: pretreatment, pre-concentration, deep concentration, evaporation, and crystallization. To achieve true zero discharge of industrial wastewater, improving the resource utilization rate of high-salt, high-organic wastewater at the end of the treatment process is crucial. The salts in industrial wastewater are mostly sodium chloride and sodium sulfate, primarily originating from three sources: ① salts introduced during demineralized water and circulating water production processes; ② chemicals added during wastewater treatment and reuse; ③ salts introduced from fresh water and raw materials required for plant production. Concentrated brine treatment is the final step in achieving zero discharge of industrial wastewater. Concentrated brine can have a TOC exceeding 1000 mg / L and a total dissolved solids of 30,000-260,000 mg / L. It contains a large amount of recalcitrant organic matter, various salts, and heavy metals.

[0003] Currently, there are two main process routes for fractional crystallization:

[0004] ① After deep concentration, the wastewater directly enters the evaporator crystallizer. Based on the different solubilities of each solute at the corresponding temperature in the solution, the phase diagram theory is used to separate the salts to obtain different salt products. The quality of the separated salts is poor and the recovery rate is low. The mother liquor of the crystallizer enters the mixed salt crystallizer, and finally a large amount of mixed salts are produced.

[0005] ② By utilizing the special pore size range and charge effect of nanofiltration membranes, sodium chloride and sodium sulfate in wastewater are separated, and then evaporated or frozen to crystallize, thereby realizing the recycling of salt. The crystallized salt obtained by this process has high purity, but eventually a portion of the crystallizer mother liquor enters the impurity salt crystallizer, producing some impurity salt.

[0006] Existing fractional crystallization technology has a salt recovery rate of only 45%-80%, but it also generates a considerable amount of mixed salts. Therefore, further resource-based treatment of high-salt and high-organic wastewater at the end of the process is of great significance.

[0007] The literature "A Brief Analysis of Salt-Nitrogenate Separation in Coal Chemical Wastewater Treatment" employs a stepwise crystallization method using sodium sulfate and sodium chloride. Sodium chloride is crystallized at a lower temperature, and sodium sulfate is crystallized at a higher temperature; this process is called the salt-nitrate co-production process. This salt-nitrate co-production crystallization process mainly utilizes the difference in temperature dependence of the solubility of sodium chloride and sodium sulfate. Between 50-120℃, the solubility of sodium chloride increases with increasing temperature, while the opposite is true for sodium sulfate, where solubility decreases with increasing temperature. Therefore, the salt-nitrate co-production crystallization process concentrates the solution at a higher temperature to the salt-nitrate co-saturation point, separating sodium sulfate; then, it is cooled and evaporated to the salt-nitrate co-saturation point to separate sodium chloride. After washing with raw water, crude nitrate and crude salt are obtained. However, in this literature, applying the salt-nitrate co-production crystallization process to the wastewater industry requires precise control of the saturation points of sodium sulfate and sodium chloride at specific temperatures, resulting in difficulties in control and poor ability to handle fluctuations in the composition of the raw water. The limited crystallization volume in a single heating / cooling operation necessitates a large amount of mother liquor reflux, which reduces process efficiency to some extent.

[0008] Patent document CN201910208369.4 discloses a zero-discharge and salt-separation crystallization system and method for coal chemical wastewater. The system includes a sequentially connected biochemical treatment unit, a reuse unit, a membrane concentration unit, and a salt-separation crystallization unit. The membrane concentration unit includes a sequentially connected pre-concentration device, a nanofiltration device, and a nanofiltration permeate reverse osmosis device. The salt-separation crystallization unit includes a sodium sulfate crystallization device and a sodium chloride crystallization device. The sodium sulfate crystallization device is connected to the concentrate outlet of the nanofiltration device, and the sodium chloride crystallization device is connected to the concentrate outlet of the nanofiltration permeate reverse osmosis device. By separately crystallizing the nanofiltration permeate and concentrate, the recovery of sodium chloride and sodium sulfate crystals is ultimately achieved. However, this process is not suitable for treating the final concentrated brine with high organic content.

[0009] In the aforementioned literature and patents, the recovery rate of crystallized salt in the fractional crystallization process is the highest at 45%-80%. After the production of industrial salt, about 20%-55% of crystalline miscellaneous salts that are difficult to reuse are still produced. In addition to sodium and potassium salts and sulfide chlorides, these salts are also enriched with complex organic substances such as benzene, lipids, quinoline and pyridine, and even small amounts of heavy metals. Therefore, they cannot be directly transported to the slag yard for simple landfilling with gasification ash and boiler ash, and must be disposed of separately as hazardous solid waste.

[0010] Patent document CN201911225710.3 discloses a bipolar membrane electrodialysis resource recovery process for high-salinity wastewater. Step 1: In the softening and clarification section, caustic soda is first added to remove magnesium ions, followed by calcium ions. Step 2: The softened wastewater enters the ultrafiltration + nanofiltration section to remove suspended solids and divalent ions. Before entering the ultrafiltration section, hydrochloric acid is added to remove carbonate ions. Step 3: The nanofiltration concentrate enters the bipolar membrane electrodialysis system, where the treated caustic soda and hydrochloric acid are reused in the softening and clarification and membrane systems, respectively. Step 4: Finally, the wastewater enters the MVR evaporator crystallizer to produce pure sodium chloride. The patent document describes the preparation of acids and bases using nanofiltration concentrate in a bipolar membrane electrodialysis system. If the high-salt wastewater has a high organic content, the organic matter will be concentrated along with the divalent salt and retained on the nanofiltration concentrate side. When the nanofiltration concentrate enters the bipolar membrane process, the negatively charged organic matter (most organic matter is negatively charged) may adhere to the surface of the anion membrane to form an electric double layer, which hinders the permeation of anions and reduces the desalination efficiency of the system. Alternatively, the organic matter may permeate through the anion membrane into the acid chamber, affecting the purity of the acid and causing membrane fouling of the bipolar membrane.

[0011] Patent document CN202010404949.3 discloses a zero-discharge treatment system for saline wastewater. This system includes a nanofiltration unit, a bipolar membrane electrodialysis unit, and a conversion crystallization unit. The permeate outlet of the nanofiltration unit is connected to the bipolar membrane electrodialysis unit, and the concentrate outlet is connected to the conversion crystallization unit. This patent document applies conversion crystallization technology to the zero-discharge treatment of saline wastewater, combining it with bipolar membrane electrodialysis technology to convert low-value-added sodium sulfate into higher-value-added sodium bicarbonate. The patent document uses a nanofiltration unit to treat saline wastewater, with the nanofiltration effluent entering the bipolar membrane unit, thus mitigating the risk of bipolar membrane fouling caused by organic matter. However, this patent document primarily utilizes the selective retention characteristics of conventional nanofiltration membranes for divalent salts to achieve the separation of monovalent sodium chloride and divalent sodium sulfate in the liquid phase. Sodium chloride mainly enters the nanofiltration permeate, while sodium sulfate is concentrated in the nanofiltration concentrate. This system can only be used for wastewater with a salinity of less than 8% and is not suitable for wastewater with higher salinity.

[0012] For complex wastewater with high salinity and high organic content, such as concentrated brine from zero-discharge wastewater treatment plants, the complexity of its composition, high salt content, and high organic matter levels make it difficult to directly apply existing wastewater treatment processes or systems suitable for low-salt and / or low-organic-content and / or simple-composition wastewater. How to further utilize this complex wastewater for resource recovery while ensuring the stability, economy, reduction of impurities, and high salt recovery rates of the process system is one of the current technical challenges in this field. Summary of the Invention

[0013] This invention provides a resource-based treatment process and system for wastewater with high salinity and high organic content. Based on the process of this invention, the treatment of wastewater with high salinity and high organic content can significantly improve the salt recovery rate and significantly reduce the generation of impurities. It avoids the disadvantages of large amounts of downstream impurities, complex composition of impurities, and large-scale and costly hazardous waste treatment. Furthermore, it can minimize the adverse effects of organic matter, especially organic matter that is difficult to be degraded by advanced oxidation, on the stability of process operation and operating costs.

[0014] To achieve the objectives of this invention, the following technical solution is provided:

[0015] This invention provides a resource-based treatment process for wastewater with high salinity and high organic content, comprising the following steps:

[0016] 1) The wastewater is sent to a softening coagulation sedimentation unit for coagulation sedimentation to remove calcium ions, magnesium ions, fluoride ions and / or silicon contained in the wastewater, as well as to remove some organic matter, to obtain product water I.

[0017] 2) The product water I is fed into an ultrafiltration resin unit for ultrafiltration and resin adsorption in sequence to remove suspended solids, solid particles and residual calcium and / or magnesium ions in the product water I to obtain product water II.

[0018] 3) The product water II is fed into the organic matter retention unit to retain the organic matter in the product water II, and the separated organic matter is used as the saline stream of product water III;

[0019] 4) The permeate III is fed into an advanced oxidation unit to degrade the residual organic matter in the permeate III, yielding permeate IV;

[0020] 5) The product water IV is sent as the raw solution to be treated into the bipolar membrane electrodialysis unit for electrodialysis to obtain acid solution, alkaline solution and desalinated fresh water;

[0021] 6) The desalinated water is fed into the membrane concentration unit and concentrated to obtain concentrate and permeate V; the concentrate is returned to the advanced oxidation unit in step 4); the permeate V is reused as wastewater.

[0022] This invention also provides a resource-based treatment system for wastewater with high salinity and high organic content, comprising:

[0023] A softening coagulation sedimentation unit is used to treat the wastewater to remove calcium ions, magnesium ions, fluoride ions and / or silicon contained therein, as well as to remove some organic matter, and to obtain product water I.

[0024] An ultrafiltration resin unit is used to sequentially treat the permeate I from the softening coagulation sedimentation unit with ultrafiltration and resin adsorption to remove suspended solids, solid particles, and residual calcium and / or magnesium ions, and obtain permeate II.

[0025] An organic matter retention unit is used to retain organic matter in the permeate II from the ultrafiltration resin unit to obtain permeate III from which organic matter has been separated.

[0026] An advanced oxidation unit is used to degrade the organic matter remaining in the product water III to obtain product water IV;

[0027] A bipolar membrane electrodialysis unit is used to electrodialyze the permeate IV from the advanced oxidation unit as the raw solution to be treated, in order to obtain acid solution, alkaline solution and desalinated fresh water.

[0028] A membrane concentration unit is used to concentrate the desalinated water using a membrane to obtain concentrate and permeate V, and to return the concentrate to the advanced oxidation unit.

[0029] In some embodiments, the resource recovery system is used for the resource recovery treatment process of high-salinity, high-organic-content wastewater described above.

[0030] The technical solution provided by this invention has the following beneficial effects:

[0031] The resource recovery process and system provided by this invention are particularly suitable for treating complex wastewater with high salinity and high organic content. They significantly reduce the impact of organic matter, especially recalcitrant organic matter, on the resource recovery system and are applicable to wastewater with a salinity of 8% or higher. When treating high-salinity, high-organic-content wastewater, they are suitable not only for monovalent and divalent salts but also for mixtures of monovalent and divalent salts. Simultaneously, they significantly reduce the production of hazardous waste containing mixed salts, thereby reducing treatment costs and increasing the resource recovery rate of wastewater. The resource recovery process and system provided by this invention have strong adaptability, exhibiting good operational stability and economy in the resource recovery treatment of high-salinity, high-organic-content wastewater, while also achieving a high salt recovery rate. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a resource recovery system for wastewater with high salinity and high organic content in one embodiment.

[0033] Figure 2 This is a schematic diagram of a bipolar membrane electrodialysis device in one implementation method.

[0034] Figure 3 This is a simplified schematic diagram illustrating the connection relationship between the bipolar membrane electrodialysis device and each circulation device.

[0035] Explanation of some figure labels:

[0036] Anode plate 1, cathode plate 2, first bipolar membrane 3, membrane unit 4, second bipolar membrane 41, first anion exchange membrane 42, second anion exchange membrane 43, first cation exchange membrane 44, second cation exchange membrane 45, electrode chambers 51, 52, acid chamber 6, circulating liquid chamber 7, salt chamber 8, alkali chamber 9, bipolar membrane electrodialysis device 100, salt chamber feed circulation device 200, brine tank 201, salt chamber feed circulation pump 202, pipeline 203, alkali circulation device 300, alkali tank 301, alkali chamber circulation pump 302, pipeline 303, acid circulation device 400, acid tank 401, acid chamber circulation pump 402, pipeline 403, circulating liquid circulation device 500, circulating liquid tank 501, circulating liquid chamber circulation pump 502, pipeline 503. Electrode circulation device 600, electrode tank 601, electrode circulation pump 602, pipeline 603. Detailed Implementation

[0037] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" may be used herein to include any and all combinations of one or more of the associated listed items.

[0039] Where specific experimental steps or conditions are not specified in the embodiments, the corresponding conventional experimental steps or conditions in this technical field can be followed.

[0040] The terms "up," "down," "left," "right," "front," "back," "front," "back," "top," and "bottom," etc., mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. They are relative concepts and may therefore vary depending on their location and usage. The terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] This invention provides a resource-based treatment process for wastewater with high salinity and high organic content, mainly comprising the following steps:

[0042] 1) The wastewater is sent to the softening coagulation sedimentation unit for coagulation sedimentation to remove calcium ions, magnesium ions, fluoride ions and / or silicon contained in the wastewater, as well as to remove some organic matter, to obtain product water I.

[0043] 2) The permeate I is fed into the ultrafiltration resin unit for ultrafiltration and resin adsorption in sequence to remove suspended solids, solid particles and residual calcium and / or magnesium ions in permeate I to obtain permeate II.

[0044] 3) The permeate II is fed into the organic matter retention unit to retain the organic matter in permeate II, and the separated organic matter is used as the saline stream of permeate III;

[0045] 4) The permeate III is fed into the advanced oxidation unit to degrade the organic matter remaining in permeate III, yielding permeate IV;

[0046] 5) The permeate IV was sent as the raw solution to be treated into the bipolar membrane electrodialysis unit for electrodialysis to obtain acid solution, alkaline solution and desalinated fresh water;

[0047] 6) The desalinated water is fed into the membrane concentration unit and treated by the membrane to obtain concentrate and permeate V; the concentrate is returned to the advanced oxidation unit in step 4) to further remove any remaining organic matter; the resulting permeate V is reused as wastewater.

[0048] The resource recovery process proposed in this invention is particularly suitable for treating complex wastewater with high salinity and high organic content, such as for further resource recovery treatment of concentrated brine generated from zero-discharge end-of-pipe systems. Resource recovery treatment of high-salinity, high-organic-content wastewater based on this invention's process can solve the problems of low salt recovery rate and large amounts of mixed salts in existing zero-discharge processes, thereby avoiding the resulting high costs of mixed salt treatment. Simultaneously, resource recovery treatment based on this invention pre-separates organic matter and salt, thus preventing large amounts of organic matter from entering downstream units, such as advanced oxidation units. This reduces the treatment load on advanced oxidation units, significantly saves treatment costs, reduces the possibility of incomplete degradation, and minimizes the entry of more organic matter that is difficult to be degraded by advanced oxidation into the advanced oxidation stage. Furthermore, it minimizes the entry of organic matter that is difficult to be degraded by advanced oxidation and / or incompletely degraded organic matter into the downstream bipolar membrane electrodialysis stage, thus preventing a shortened bipolar membrane lifespan and avoiding adverse effects on the smoothness and stability of the overall process system operation. Furthermore, in the process of this invention, for wastewater containing monovalent and divalent salts, the monovalent and divalent salts will not, or mostly will not, be separated from the process system during treatment. Instead, they will essentially enter the subsequent bipolar membrane electrodialysis section to generate acids and alkalis. On the one hand, this can significantly reduce the production of impurities, thereby reducing the difficulty and cost of subsequent disposal of impurities. On the other hand, based on the process of this invention, through the ingenious coordination of each section, the salt recovery rate can be greatly improved, effectively ensuring the stability of process operation while also taking into account economic efficiency.

[0049] In this invention, the high-salinity, high-organic-content wastewater has a salt content of 8 wt% or more and a TOC of 100 mg / L or more. Furthermore, the high-salinity, high-organic-content wastewater also contains organic matter that cannot be degraded by advanced oxidation processes, such as long-chain alkanes, heterocyclic compounds, or polycyclic aromatic hydrocarbons, which are difficult to degrade using advanced oxidation technologies. For example, the process of this invention can also be applied to the resource recovery treatment of wastewater where the proportion of organic matter that is difficult to degrade by advanced oxidation technologies is ≤60 wt%.

[0050] In this invention, the high-salinity, high-organic-content wastewater contains monovalent and / or divalent salts, such as a mixed salt containing monovalent and divalent salts. Accordingly, the product water III in step 3) is a saline stream containing monovalent and / or divalent salts.

[0051] In some embodiments, the salt content of the high-salinity, high-organic-content wastewater is 8wt%-20wt%, preferably 10-18wt%, and the TOC is 100-1500mg / L.

[0052] In the process of this invention, in step 3), a special nanofiltration membrane is used in the organic matter retention unit to treat the permeate II. The special nanofiltration membrane refers to a nanofiltration membrane capable of retaining organic matter, with a retention rate of <5 wt% for divalent salts and no retention for monovalent salts. Such special nanofiltration membranes can be commercially available, for example, but not limited to, Zhejiang Meiyi Membrane Technology Co., Ltd., LCRNF; Beijing OriginWater Technology Co., Ltd., DF30, etc. Using such an organic matter retention unit achieves the separation of organic matter and salts, and it does not retain or only slightly retains divalent salts, with a divalent salt retention rate of less than 5 wt%. This ensures that most organic matter is retained on the nanofiltration concentrate side, while most salts, including divalent salts, permeate through the membrane into the nanofiltration permeate side, i.e., into permeate III. In some embodiments, the organic matter retention unit includes multiple stages of special nanofiltration membranes; preferably, the organic matter retention unit has a retention rate of 65-85 wt% (calculated based on TOC) for organic matter. This invention does not separate monovalent and divalent salts separately in the organic matter retention unit, which overcomes the limitation of the maximum allowable operating pressure (usually 3-4 MPa) in existing nanofiltration processes. Therefore, it is less affected by the salt osmotic pressure on both sides of the membrane during implementation, and can treat high-salt wastewater (e.g., salt content up to 20%) under low operating pressure with low energy consumption.

[0053] In step 5), the bipolar membrane electrodialysis unit can use a conventional bipolar membrane electrodialysis device for electrodialysis treatment.

[0054] In the preferred embodiment, see Figure 2In step 5), the bipolar membrane electrodialysis unit employs a structurally improved bipolar membrane electrodialysis device 100 for electrodialysis. This improved bipolar membrane electrodialysis device includes an anode plate 1, a membrane stack, and a cathode plate 2 arranged sequentially. The membrane stack includes a first bipolar membrane 3 and one or more membrane units 4 (…). Figure 2 Specifically, the diagram shows two membrane units 4. The first bipolar membrane 3 is adjacent to the cathode plate 2. The membrane unit 4 is disposed between the first bipolar membrane 3 and the anode plate 1. When multiple membrane units 4 are present, they are sequentially and spaced apart between the first bipolar membrane 3 and the anode plate 1. Each membrane unit 4 includes a second bipolar membrane 41, a first anion exchange membrane 42, a second anion exchange membrane 43, a first cation exchange membrane 44, and a second cation exchange membrane 45, which are sequentially and spaced apart from the anode plate 1 to the cathode plate 2. The second bipolar membrane 41 of the membrane unit 4 adjacent to the anode plate 1 and the anode plate 1, as well as the cathode plate 2 and the first bipolar membrane 3, respectively form electrode chambers 51 and 52, namely the anode chamber 51 and the cathode chamber 52, which are referred to as electrode chambers in this document. In each membrane unit 4, an acid chamber 6 is formed between the second bipolar membrane 41 and the first anion exchange membrane 42; circulating liquid chambers 7 are formed between the first anion exchange membrane 42 and the second anion exchange membrane 43, and between the first cation exchange membrane 44 and the second cation exchange membrane 45, respectively. A salt chamber 8 is formed between the second anion exchange membrane 43 and the first cation exchange membrane 44, and the salt chamber 8 has a salt chamber inlet for inputting the raw solution to be treated and a salt chamber outlet for outputting desalinated fresh water. An alkali chamber 9 is formed between the second cation exchange membrane 45 of the membrane unit 4 adjacent to the first bipolar membrane 3 and the first bipolar membrane 3. See also Figure 2 When multiple membrane units 4 exist, an alkaline chamber 9 is formed between the second cation exchange membrane 45 of the preceding membrane unit and the second bipolar membrane 41 of the adjacent following membrane unit in the direction from the anode plate 1 to the cathode plate 2. Figure 2The diagram illustrates a bipolar membrane electrodialysis device with two membrane units 4. Preferably, the number of membrane units 4 is two or more, for example, the number of membrane units 4 is ≥2 and ≤100. In step 5), the raw solution to be treated is introduced into the salt chamber 8 through the salt chamber inlet, the electrode solution is introduced into the electrode chamber, the circulating solution is introduced into the circulating solution chamber 7, and deionized water is introduced into the acid chamber 6 and the alkali chamber 9; through electrodialysis, acid solution and alkali solution are generated in the acid chamber 6 and the alkali chamber 9 respectively, and desalinated fresh water is obtained in the salt chamber 8. Preferably, in the bipolar electrodialysis unit, the circulating liquid introduced into the circulating liquid chamber 7 is brine prepared in equal proportions according to the inorganic anion and cation components of the permeate IV of the advanced oxidation unit; preferably, when the TOC value of the circulating liquid in the circulating liquid chamber is 0.8-1.6 of the TOC value of the permeate IV of the advanced oxidation unit, fresh circulating liquid is replaced ("fresh" here refers to circulating liquid that has not been used after preparation). This can further improve the retention effect of organic matter that may remain in the raw solution to be treated, which is conducive to further improving the operational stability of the bipolar membrane electrodialysis device and helps to obtain inorganic acids or bases with fewer impurities. The bipolar membrane electrodialysis device employs a preferred structure. Through a special membrane stack configuration, and within each membrane unit 4, a first anion exchange membrane 42, a second anion exchange membrane 43, a first cation exchange membrane 44, and a second cation exchange membrane 45 are sequentially and adjacently arranged between two bipolar membranes. This effectively retains any residual organic matter in the feed solution, particularly organic matter that cannot be degraded by the upstream advanced oxidation unit. This separates organic matter from salts and prevents contamination of the bipolar membranes by these organic substances, further ensuring the stable operation of the bipolar membrane electrodialysis device. The special membrane stack structure and feed flow path arrangement facilitate the production of inorganic acids and bases with fewer impurities in the acid chamber 6 and alkali chamber 9.

[0055] In some embodiments, in each membrane unit 4, one or more anion exchange membranes are further disposed between the first anion exchange membrane 42 and the second anion exchange membrane 43, and / or one or more cation exchange membranes are further disposed between the first cation exchange membrane 44 and the second cation exchange membrane 45. Using such membrane units can further improve the retention effect of organic matter, further reduce the possibility of bipolar membrane fouling, and further improve the quality of acids and bases. Specifically, in each membrane unit, the number of adjacent anion exchange membranes (including the first and second anion exchange membranes mentioned above, and one or more anion exchange membranes that may be disposed between them) can be two or more, and the number of adjacent cation exchange membranes (including the first and second cation exchange membranes mentioned above, and one or more cation exchange membranes that may be disposed between them) can be two or more, and the number of anion exchange membranes and the number of cation exchange membranes can be the same or different. As mentioned above, the spaces between two adjacent anion exchange membranes (the "anion exchange membranes" mentioned here include the first and second anion exchange membranes mentioned above, as well as one or more anion exchange membranes that may be located between them) and between two adjacent cation exchange membranes (the "cation exchange membranes" mentioned here include the first and second cation exchange membranes mentioned above, as well as one or more cation exchange membranes that may be located between them) are all circulation liquid chambers. During operation, the circulation liquid chambers are filled with circulating liquid.

[0056] The preferred bipolar membrane electrodialysis device described above, through the ingenious design of the membrane stack structure and feed flow path, exhibits high selectivity for organic matter. It can greatly reduce the permeation of charged or uncharged organic matter through the anion exchange membrane or cation exchange membrane via electromigration or migration with water molecules. It effectively retains organic matter that has not been retained or degraded in upstream process sections (such as the organic matter retention unit and the advanced oxidation unit), reducing the possibility of organic matter entering the acid chamber 6 and the alkali chamber 9, and effectively mitigating the pollution of the bipolar membrane by organic matter.

[0057] Both the first bipolar membrane 3 and the second bipolar membrane 41 can be conventional bipolar membranes in the art. As is well known to those skilled in the art, a bipolar membrane is composed of a cation exchange layer, an intermediate hydrophilic layer (catalytic layer), and an anion exchange layer. Under the action of a DC electric field, the water in the intermediate hydrophilic layer of the bipolar membrane dissociates, forming hydrogen ions and hydroxide ions on both sides of the bipolar membrane, respectively. The bipolar membrane electrodialysis system, assembled from the bipolar membrane, anion exchange membrane, and cation exchange membrane, can convert the salts in the raw solution to be treated into the corresponding acids and bases without introducing new components.

[0058] In some embodiments, the anion exchange membrane, such as the first anion exchange membrane 42, the second anion exchange membrane 43, or one or more anion exchange membranes that may exist between the two, and the cation exchange membrane, such as the first cation exchange membrane 44, the second cation exchange membrane 45, or one or more cation exchange membranes that may exist between the two, can be homogeneous membranes or heterogeneous membranes, preferably homogeneous membranes. In the bipolar membrane electrodialysis device of the present invention, the above-mentioned anion exchange membranes and cation exchange membranes do not need to have multiple ion valence state selectivity, for example, a multivalent ion exchange membrane is not required.

[0059] In some implementations, in a bipolar membrane electrodialysis unit, a water distribution baffle (not shown in the figure) is provided between adjacent membranes in the membrane stack.

[0060] In some embodiments, the cathode plate 2 in the bipolar membrane electrodialysis unit is a stainless steel or titanium-coated ruthenium or nickel electrode, and the anode plate 1 is a titanium-coated ruthenium electrode, titanium-coated platinum electrode, platinum electrode, or nickel electrode. The cathode plate 2 is connected to the power supply cathode, and the anode plate 1 is connected to the power supply anode. The power supply can be a regulated power supply or a regulated current power supply.

[0061] Specifically, the bipolar membrane electrodialysis unit also includes a salt chamber feed circulation device 200, an electrode liquid circulation device 600, an alkali circulation device 300, an acid circulation device 400, and a circulating liquid circulation device 500, as can be found in [reference needed]. Figure 3 , Figure 3 The diagram primarily illustrates the piping and connections between each circulation device and the bipolar membrane electrodialysis unit 100; other parts are shown only briefly. Specifically, the inlet of the salt chamber feed circulation device 200 is connected to the salt chamber outlet, and the outlet of the salt chamber feed circulation device 200 is connected to the salt chamber inlet, creating a circulating flow of feed solution within the salt chamber 8 between the salt chamber and the salt chamber feed circulation device 200. The salt chamber feed circulation device 200 specifically includes a brine tank 201 and a salt chamber feed circulation pump 202. The brine tank 201 can be used to store the raw solution to be treated (permeate IV from the advanced oxidation unit). For example, the salt chamber outlet is connected to the inlet of the brine tank 201 via a pipeline, and the salt chamber inlet is connected to the outlet of the brine tank 201 via a pipeline 203, on which the salt chamber feed circulation pump 202 is installed. An overflow port is provided on the brine tank 201 for desalination and desalination output.

[0062] Specifically, the outlet of the polar liquid circulation device 600 is connected to the inlet of the polar chamber, and the inlet of the polar liquid circulation device is connected to the outlet of the polar chamber, so that the polar liquid in the polar chamber forms a circulating flow between the polar chamber and the polar liquid circulation device 600. For example, the polar liquid circulation device 600 includes a polar liquid tank 601 and a polar liquid circulation pump 602. The polar liquid tank 601 stores polar liquid. The inlet of the polar chamber is connected to the outlet of the polar liquid tank 601 through a pipeline 603, and the polar liquid circulation pump 602 is connected to the pipeline. The outlet of the polar chamber is connected to the inlet of the polar liquid storage tank through a pipeline.

[0063] Specifically, the inlet of the alkali circulation device 300 is connected to the outlet of the alkali chamber 9, and the outlet of the alkali circulation device 300 is connected to the inlet of the alkali chamber 9, so that the alkali solution in the alkali chamber 9 forms a circulating flow between the alkali chamber 9 and the alkali circulation device 300. For example, the alkali circulation device 300 includes an alkali tank 301 and an alkali chamber circulation pump 302. The inlet of the alkali chamber 9 is connected to the outlet of the alkali tank 301 via a pipeline 303, and the alkali chamber circulation pump 302 is connected to this pipeline. The outlet of the alkali chamber 9 is connected to the inlet of the alkali tank via a pipeline. The alkali chamber 9 is also provided with a deionized water inlet for introducing deionized water. An overflow port is provided on the alkali tank 301 for alkali output.

[0064] Specifically, the inlet of the acid circulation device 400 is connected to the outlet of the acid chamber 6, and the outlet of the acid circulation device 400 is connected to the inlet of the acid chamber 6, so that the liquid in the acid chamber 6 forms a circulating flow between the acid chamber and the acid circulation device 400. For example, the acid circulation device 400 includes an acid tank 401 and an acid chamber circulation pump 402. The inlet of the acid chamber 6 is connected to the outlet of the acid tank 401 via a pipeline 403, and the acid chamber circulation pump 402 is connected to this pipeline. The outlet of the acid chamber 6 is connected to the inlet of the acid tank 401 via a pipeline. The acid chamber 6 is also provided with a deionized water inlet for introducing deionized water. An overflow port is provided on the acid tank 401 for acid output.

[0065] Specifically, the inlet of the circulating fluid circulation device 500 is connected to the outlet of the circulating fluid chamber 7, and the outlet of the circulating fluid tank 501 is connected to the inlet of the circulating fluid chamber 7, so that the circulating fluid in the circulating fluid chamber 7 forms a circulating flow between the circulating fluid chamber 7 and the circulating fluid circulation device 500. For example, the circulating fluid circulation device 500 includes a circulating fluid tank 501 and a circulating fluid chamber circulation pump 502. The inlet of the circulating fluid chamber and the outlet of the circulating fluid tank 501 are connected through a pipeline 503, and the circulating fluid chamber circulation pump 502 is connected to this pipeline. The outlet of the circulating fluid chamber and the inlet of the circulating fluid tank are connected through a pipeline.

[0066] The preferred bipolar membrane electrodialysis devices described above are improvements on existing bipolar membrane electrodialysis devices. Unless otherwise specified, all structures of bipolar membrane electrodialysis devices are conventional and can be known or understood by those skilled in the art based on their conventional technical means or common knowledge, and will not be elaborated here.

[0067] For example, during operation of the bipolar membrane electrodialysis circulation unit, the cathode plate 2 and anode plate 1 of the bipolar membrane electrodialysis device are connected to a DC power supply. The raw solution to be treated, stored in the brine tank, is introduced into the salt chamber 8. Deionized water of the same volume as the raw solution to be treated in the salt chamber 8 is introduced into the acid chamber 6 and the alkali chamber 9 through their respective deionized water inlets. The salt chamber feed pump, polar liquid pump, alkali chamber pump, acid chamber pump, and circulating liquid chamber pump are turned on. After the liquid level stabilizes, the DC power supply is turned on to energize the membrane stack, and the current or voltage value is adjusted. Anions and cations in the salt chamber 8 enter the acid chamber 6 and alkali chamber 9, respectively, reacting with hydrogen ions in the acid chamber 6 to form acid, and reacting with hydroxide ions in the alkali chamber 9 to form alkali. In some embodiments, the final concentrations of the acid and alkali solutions are 8-10 wt%. In some implementations, the bipolar membrane electrodialysis unit operates in an intermittent or continuous manner. Continuous operation means that during the operation of the bipolar membrane electrodialysis unit, raw solution to be treated from other sections is continuously introduced into the raw solution storage tank, while intermittent operation means that raw solution is continuously introduced into the storage tank.

[0068] In some implementations, the operating current density of the bipolar membrane electrodialysis unit is 100-2000 A / m. 2 The flow velocity on the membrane surface is 1-15 cm / s, the electrode solution is a sodium hydroxide aqueous solution with a mass concentration of 1-5%, and water distribution baffles are provided between adjacent membranes in the membrane stack, with the thickness of the water distribution baffles ≤ 5 mm.

[0069] In some embodiments, the sodium salt in the permeate IV obtained by the advanced oxidation unit is sodium chloride, with a sodium chloride concentration of, for example, 8.5-15 wt%; in some embodiments, the sodium salt in the permeate IV obtained by the advanced oxidation unit is sodium sulfate, with a sodium sulfate concentration of, for example, 10.7-18 wt%; in some embodiments, the sodium salt in the permeate IV obtained by the advanced oxidation unit is a mixture of sodium sulfate and sodium chloride, with the sum of their percentage contents being 9-16 wt%.

[0070] In some embodiments, the equivalent concentrations of the alkaline and acidic products obtained in the acid and alkaline solutions obtained by the bipolar membrane electrodialysis unit are 0.5-4N, preferably 1.5-2.5N.

[0071] In the process of this invention, the salt in the raw solution to be treated is converted into inorganic acid and alkali through the treatment in step 5). The resulting acid and / or alkali solution can be reused for resin regeneration in the ultrafiltration resin unit, or used as a pH adjuster in the wastewater treatment process to adjust the pH value.

[0072] In some embodiments, step 1) of the softening coagulation sedimentation unit includes one or more softening coagulation sedimentation sub-units arranged in series. In practical applications, the required number of series stages can be determined according to the treatment requirements. For example, it may include only one softening coagulation sedimentation sub-unit, or it may include one, two, or more softening coagulation sedimentation sub-units. Coagulation sedimentation of wastewater to remove calcium and magnesium ions, silicon (mainly active silicon), fluoride ions, and some organic matter is a conventional treatment technology in the art. It can be carried out using conventional treatment devices and processes in the art, without any particular limitation. Conventional processes in the art include, for example, adding chemicals to the softening coagulation sedimentation unit to coagulate and precipitate the wastewater. Conventional chemicals include (calcium hydroxide and / or sodium hydroxide), sodium carbonate, coagulants (e.g., polyaluminum, polyferric, etc.), flocculants (e.g., polyamide, etc.). In some embodiments, in step 1), the permeate I obtained after treatment by the softening coagulation sedimentation unit has calcium ions <10 mg / L, magnesium ions <2 mg / L, iron ions <0.1 mg / L, manganese ions <0.1 mg / L, silicon <5 mg / L, fluoride ions <15 mg / L, suspended solids <100 mg / L, and an organic matter removal rate of 8-10 wt% (calculated based on TOC), where silicon refers to activated silicon.

[0073] In some embodiments, in step 2), the ultrafiltration membrane in the ultrafiltration resin unit is selected from one or more combinations of organic ultrafiltration membranes and inorganic ceramic membranes. The specific component form of the ultrafiltration membrane is, for example, but not limited to, flat sheet membranes, hollow fiber membranes, and spiral wound membranes. In step 2), the resin in the ultrafiltration resin unit is preferably a cationic chelating resin, which can be regenerated by acid or alkali, for example, by using acid or alkali solutions generated in a downstream bipolar membrane electrodialysis unit. The aforementioned suitable cationic chelating resins can be commercially available, for example, but not limited to, Purolite S930Plus, Dusheng CH-93, and Lanxiao Technology LSC-100. By removing suspended solids, particulate matter, and residual hardness (i.e., removing residual calcium and / or magnesium ions) from product water I through the ultrafiltration resin unit in step 2), product water II is obtained. In some embodiments, the permeate II obtained after treatment by the ultrafiltration resin unit in step 2) contains calcium ions <1 mg / L, magnesium ions <1 mg / L, iron ions <0.1 mg / L, manganese ions <0.1 mg / L, silicon <2 mg / L, fluoride ions <15 mg / L, suspended solids ≤0.1 mg / L, and organic matter removal rate of 3-5% (calculated based on TOC), where silicon refers to activated silicon.

[0074] In some embodiments, the oxidation process used in the advanced oxidation unit in step 4) can be a conventional advanced oxidation process in the art, such as, but not limited to, one or more combinations of ozone oxidation, ozone catalytic oxidation, Fenton oxidation, electrocatalytic oxidation, ozone-co-Fenton oxidation, and ozone-co-UV oxidation. In some embodiments, the advanced oxidation unit in step 4) achieves a removal rate of 50-70 wt% (based on TOC) of organic matter.

[0075] In some embodiments, in step 6), the desalinated water enters a membrane concentration unit for membrane concentration, resulting in concentrate with a salt content of 12 wt% or higher; in some embodiments, the salt content of the concentrate is 12 wt%-18 wt%. This concentrate is then returned to the advanced oxidation unit for further treatment, thereby further treating any residual organic matter in the concentrate and improving salt and water recovery rates without potentially adversely affecting the bipolar membrane electrodialysis unit due to any residual organic matter. In some embodiments, in step 6), the desalinated water is treated by the membrane concentration unit, and the recovery rate of the produced permeate V is 40-75% (v / v). The produced permeate V is reused as greywater in other water-consuming processes. In some embodiments, increasing the salt content of the desalinated water through the membrane concentration unit, for example, from 3-5% to over 12%, such as to 15% or 18%, is beneficial for improving the operating efficiency and salt recovery rate of the system.

[0076] In some embodiments, the membrane concentration unit may employ one or more of the following processes: electrodialysis, membrane distillation, forward osmosis, seawater reverse osmosis, high-pressure reverse osmosis, and butterfly tube reverse osmosis. The membrane concentration device and process used in the membrane concentration unit can employ conventional and appropriate devices and processes in the art, without particular limitation. For example, the membrane concentration unit includes a membrane element, a membrane housing, and associated water pumps, high-pressure pumps, and pipelines. Specifically, the membrane concentration unit may include one or more membrane concentration sub-units, and the processing temperature of the membrane concentration unit may be, for example, 20-50°C.

[0077] The process provided by this invention is used for the resource recovery treatment of wastewater with high salinity and high organic content, especially for the end-of-pipe treatment of high salinity and high organic content wastewater in zero-discharge processes. This can improve the resource recovery rate of wastewater, allowing more salts, such as monovalent and divalent salts, to enter subsequent processes to prepare inorganic acids and alkalis, and to be directly reused for resin regeneration or pH adjustment in wastewater treatment plants, thus achieving a circular economy. The salt recovery rate is greatly improved, ultimately reducing the amount of miscellaneous salts generated and realizing the resource recovery of miscellaneous salts. Zero-discharge end-of-pipe brine often contains recalcitrant organic matter, especially organic matter that cannot be completely degraded by advanced oxidation technologies. In this invention, organic matter is separated in an organic matter retention unit, such as one based on a special nanofiltration membrane, allowing most of the salt (including monovalent and divalent salts) to enter the permeate III. This achieves the separation of most organic matter, especially recalcitrant organic matter, from salt with minimal salt loss, reducing the processing load and difficulty of subsequent stages. This is further processed by subsequent advanced oxidation, bipolar membrane electrodialysis, and membrane concentration units, with the concentrate from the membrane concentration unit being recycled back to the advanced oxidation unit. The overall process exhibits good operational stability, excellent salt recovery rate, and high system efficiency. Using this resource-based treatment process, the evaporation and crystallization processes in existing zero-discharge processes can be partially or completely replaced, resulting in a significantly improved salt recovery rate.

[0078] The resource recovery process of the present invention can be used to treat the mother liquor of the evaporator in the zero-emission process, which can not only improve the salt recovery rate, but also reduce the processing scale of the crystallizer and the mixed salt crystallizer in the subsequent process.

[0079] In practical applications, the processing scale of the process of this invention can be determined by calculating the overall acid and alkali usage requirements of the plant area, so that the generated acid and alkali matches the acid and alkali usage requirements of the plant area, thereby achieving the best economic benefits.

[0080] In some implementations, the organic stream (concentrate sidestream) separated from the organic matter retention unit (e.g., an organic matter retention unit based on a special nanofiltration membrane) is discharged to a mixed salt crystallizer, for example, to a mixed salt crystallizer in an existing zero-discharge industrial wastewater project.

[0081] A second aspect of this invention also provides a resource recovery system for wastewater with high salinity and high organic content, see [link to relevant documentation]. Figure 1 Mainly includes:

[0082] The softening coagulation sedimentation unit is used to treat wastewater to remove calcium ions, magnesium ions, fluoride ions and / or silicon contained therein, as well as to remove some organic matter, and to obtain product water I.

[0083] The ultrafiltration resin unit is used to sequentially perform ultrafiltration and resin adsorption on the wastewater (i.e., product water I) after it has been treated by the softening coagulation sedimentation unit to remove suspended solids, solid particles and residual calcium and / or magnesium ions, and to obtain product water II.

[0084] The organic matter retention unit is used to retain organic matter in the wastewater (i.e., product water II) treated by the ultrafiltration resin unit to obtain product water III from which organic matter has been separated.

[0085] Advanced oxidation unit, used to degrade residual organic matter in product water III to obtain product water IV;

[0086] The bipolar membrane electrodialysis unit is used to electrodialyze the permeate IV from the advanced oxidation unit as the raw solution to obtain acid solution, alkaline solution and desalinated fresh water.

[0087] The membrane concentration unit is used to concentrate desalinated water to obtain concentrate and permeate V, and the concentrate is returned to the advanced oxidation unit.

[0088] The resource recovery system provided by this invention can be used to implement the resource recovery process described above. All relevant details regarding this resource recovery system can be found in the corresponding descriptions given in the resource recovery process section above; further elaboration will not be repeated below.

[0089] In some embodiments, the organic matter retention unit in the resource recovery treatment system includes a special nanofiltration membrane, that is, the special nanofiltration membrane separates organic matter and salt, allowing the organic matter to enter the concentrate side and the salt to enter the product water side. Specifically, the special nanofiltration membrane refers to a nanofiltration membrane capable of retaining organic matter, with a retention rate of <5 wt% for divalent salts and no retention rate for monovalent salts; such special nanofiltration membranes can be commercially available, for example, but not limited to, Zhejiang Meiyi Membrane Technology Co., Ltd., LCRNF; Beijing OriginWater Technology Co., Ltd., DF30, etc. In some embodiments, the organic matter retention unit includes a multi-stage special nanofiltration membrane; preferably, the organic matter retention unit has a retention rate of 65-85 wt% for organic matter. Using the above-mentioned organic matter retention unit, on the one hand, separation of organic matter and salt can be achieved; on the other hand, during operation, it is less affected by the osmotic pressure of salt on both sides of the membrane, and can treat high-salt wastewater (e.g., salt content up to 20%) under low operating pressure, with low process energy consumption.

[0090] The bipolar membrane electrodialysis unit can use a conventional bipolar membrane electrodialysis device for electrodialysis treatment.

[0091] In a preferred embodiment, the bipolar membrane electrodialysis unit employs a structurally improved bipolar membrane electrodialysis device for electrodialysis, see [link to relevant documentation]. Figure 2The improved bipolar membrane electrodialysis device includes an anode plate 1, a membrane stack, and a cathode plate 2 arranged sequentially. The membrane stack includes a first bipolar membrane 3 and one or more membrane units 4. The first bipolar membrane 3 is adjacent to the cathode plate 2. The membrane units 4 are disposed between the first bipolar membrane 3 and the anode plate 1. When multiple membrane units 4 are present, they are arranged sequentially and spaced apart between the first bipolar membrane 3 and the anode plate 1. Each membrane unit 4 includes a second bipolar membrane 41, a first anion exchange membrane 42, a second anion exchange membrane 43, a first cation exchange membrane 44, and a second cation exchange membrane 45 arranged sequentially and spaced apart from the anode plate 1 to the cathode plate 2. The second bipolar membrane 41 of the membrane unit 4 adjacent to the anode plate 1 forms an anode chamber 51 and a cathode chamber 52, respectively, between the anode plate 1 and the cathode plate 2 and the first bipolar membrane 3. These are referred to as anode chamber 51 and cathode chamber 52, respectively, and are simply referred to as anode chambers in this document. In each membrane unit 4, an acid chamber 6 is formed between the second bipolar membrane 41 and the first anion exchange membrane 42; circulating liquid chambers 7 are formed between the first anion exchange membrane 42 and the second anion exchange membrane 43, and between the first cation exchange membrane 44 and the second cation exchange membrane 45, respectively; a salt chamber 8 is formed between the second anion exchange membrane 43 and the first cation exchange membrane 44, and the salt chamber 8 has a salt chamber inlet for inputting the raw solution to be treated and a salt chamber outlet for outputting desalinated fresh water. An alkali chamber 9 is formed between the second cation exchange membrane 45 of the membrane unit 4 adjacent to the first bipolar membrane 3 and the first bipolar membrane 3. See also... Figure 2 When multiple membrane units 4 exist, an alkaline chamber 9 is formed between the second cation exchange membrane 45 of the preceding membrane unit and the second bipolar membrane 41 of the adjacent following membrane unit in the direction from the anode plate 1 to the cathode plate 2. Figure 2 The diagram illustrates a bipolar membrane electrodialysis unit with two membrane units 4. Employing the aforementioned preferred structure, the bipolar membrane electrodialysis unit, through a clever membrane stack design, arranges a first anion exchange membrane 42, a second anion exchange membrane 43, a first cation exchange membrane 44, and a second cation exchange membrane 45 sequentially and adjacently between the two bipolar membranes in each membrane unit 4. Combined with the specific arrangement of each chamber, this effectively traps any residual organic matter in the raw solution being treated, particularly organic matter that cannot be degraded by the upstream advanced oxidation unit. This separates organic matter from salts and prevents contamination of the bipolar membranes, ensuring stable operation of the bipolar membrane electrodialysis unit. Furthermore, the special membrane stack structure facilitates the production of inorganic acids and bases with fewer impurities in the acid chamber 6 and the alkali chamber 9. Using this preferred bipolar membrane electrodialysis unit improves the operational stability of the entire process system and enhances the quality of acids and bases.

[0092] In a preferred embodiment, the number of membrane units 4 is preferably two or more, and more preferably ≤100. For example... Figure 2 As shown, it is a bipolar membrane electrodialysis device equipped with two membrane units 4.

[0093] In some embodiments, each membrane unit 4 includes one or more anion exchange membranes between the first anion exchange membrane 42 and the second anion exchange membrane 43, and / or one or more cation exchange membranes between the first cation exchange membrane 44 and the second cation exchange membrane 45. Using such membrane units can further improve the retention of organic matter, further reduce the possibility of bipolar membrane fouling, and further improve the quality of acids and bases. Specifically, in each membrane unit, the number of adjacent anion exchange membranes can be two or more, and the number of adjacent cation exchange membranes can be two or more types, and the number of anion exchange membranes and cation exchange membranes can be the same or different. As mentioned above, the spaces between two adjacent anion exchange membranes and between two adjacent cation exchange membranes are each designated as circulating liquid chambers.

[0094] For detailed implementation, see Figure 3 The bipolar membrane electrodialysis unit also includes a salt chamber feed solution circulation device, an electrode liquid circulation device, an alkali solution circulation device, an acid solution circulation device, and a circulating liquid circulation device. The inlet of the salt chamber feed solution circulation device is connected to the salt chamber outlet, and the outlet of the salt chamber feed solution circulation device is connected to the salt chamber inlet, creating a circulating flow of the feed solution within the salt chamber 8 between the salt chamber and the salt chamber feed solution circulation device. The inlet of the electrode liquid circulation device is connected to the electrode chamber outlet, and the outlet of the electrode liquid circulation device is connected to the electrode chamber inlet, creating a circulating flow of the electrode liquid within the electrode chamber between the electrode chamber inlet and the electrode liquid circulation device. The inlet of the alkali solution circulation device is connected to the alkali chamber outlet, and the outlet of the alkali solution circulation device is connected to the alkali chamber inlet, creating a circulating flow of the feed solution within the alkali chamber 9 between the alkali chamber 9 and the alkali solution circulation device; the alkali chamber 9 also has a deionized water inlet for introducing deionized water. The inlet of the acid circulation device is connected to the outlet of acid chamber 6, and the outlet of the acid circulation device is connected to the inlet of acid chamber 6, creating a circulating flow of the liquid in acid chamber 6 between acid chamber 6 and the acid circulation device. Acid chamber 6 is also equipped with a deionized water inlet for introducing deionized water. The inlet of the circulating liquid circulation device is connected to the outlet of circulating liquid chamber 7, and the outlet of the circulating liquid circulation device is connected to the inlet of the circulating liquid chamber, creating a circulating flow of the circulating liquid in circulating liquid chamber 7 between circulating liquid chamber 7 and the circulating liquid circulation device. Specific descriptions of the above circulation devices can be found in the corresponding descriptions above, and will not be repeated here.

[0095] For a description of the improved bipolar membrane electrodialysis device, please refer to the previous explanation of the resource recovery process regarding the improved bipolar membrane electrodialysis device; it will not be repeated here.

[0096] In some embodiments, the ultrafiltration resin unit includes ultrafiltration sub-units and resin sub-units connected in series. The ultrafiltration membrane in the ultrafiltration sub-unit may be selected from one or more combinations of organic ultrafiltration membranes and inorganic ceramic membranes. The specific component form of the ultrafiltration membrane is, for example, but not limited to, flat sheet membranes, hollow fiber membranes, and spiral wound membranes. In some embodiments, the resin in the resin sub-unit is preferably a cationic chelating resin.

[0097] The resource recovery system provided by this invention is particularly suitable for the resource recovery treatment of wastewater with high salinity and high organic content. It is applicable to the treatment of wastewater with complex composition, high ionic strength, high salinity, and high organic content. It can minimize the adverse effects of organic matter, especially that which is difficult to be degraded by advanced oxidation, on process stability and operating costs. Simultaneously, it can significantly reduce the generation of impurities, avoiding the drawbacks of low salt recovery rate, difficult impurity treatment, and high treatment costs caused by large amounts of impurities. The resource recovery system of this invention, when used for the resource recovery treatment of wastewater with high salinity and high organic content, can simultaneously achieve advantages such as good system operational stability, low operating costs, high salt recovery rate, and strong applicability.

[0098] Existing fractional crystallization processes for miscellaneous salts achieve a maximum salt recovery rate of 45%-80%. After industrial salt production, approximately 20%-55% of unusable crystalline miscellaneous salts are still generated. These miscellaneous salts must be disposed of as hazardous solid waste, wasting resources and incurring high treatment costs (3500-5000 RMB / ton). This invention provides a resource-based treatment process and system for wastewater with high salt and organic matter content. After pretreatment, the wastewater sequentially passes through an organic matter interception unit, an advanced oxidation unit, and a bipolar membrane electrodialysis unit. The desalinated water obtained from the bipolar membrane electrodialysis unit is then sent to a membrane concentration unit, and the concentrated water is returned to the advanced oxidation unit. This process converts most of the salts in the wastewater into corresponding acids and alkalis without introducing new components. The salt recovery rate in the wastewater is significantly improved compared to existing processes, ultimately reducing the amount of miscellaneous salts generated and lowering the cost of hazardous waste treatment.

[0099] For wastewater with high salinity and high organic content, such as concentrated brine at the end of zero-discharge processes, which often contains recalcitrant organic matter that cannot be completely degraded by advanced oxidation technologies, this invention improves the resource-based treatment process or system. Through the ingenious combination of various units and the arrangement of feed flow in each material treatment unit with specific treatment flow directions, the wastewater with high salinity and high organic content is treated by a softening, coagulation, and sedimentation unit and an ultrafiltration resin unit. It is then first sent to an organic matter interception unit, and then the saline stream enters the advanced oxidation unit. Afterward, the salt in the wastewater is converted into inorganic acids and alkalis by a bipolar membrane electrodialysis unit. The desalinated water is further concentrated by membrane filtration and then returned to the advanced oxidation unit. With minimal salt loss, this invention can greatly reduce the impact of organic matter, especially recalcitrant organic matter, on the stability of system operation, and avoid the stringent requirements and increased treatment costs of the advanced oxidation unit due to complex composition and the presence of recalcitrant organic matter. On the other hand, it can significantly reduce the generation of impurities and improve the salt recovery rate.

[0100] The resource recovery process and system provided by this invention: 1) overcomes the impact of organic matter, especially organic matter that is difficult to degrade even with advanced oxidation, on the concentrated brine resource recovery treatment unit; 2) is applicable to the resource recovery treatment of complex high-salinity brine, with an applicable brine concentration range of 8 wt% or higher, for example, 8-20 wt%; 3) when used to treat high-salinity wastewater with high organic matter content, it is applicable not only to monovalent salts and divalent salts, but also to mixed salts of monovalent and divalent salts; 4) can significantly reduce the production of mixed salt hazardous waste, reduce the treatment cost of mixed salt hazardous waste, and improve the resource recovery rate of wastewater; 5) has strong shock resistance and is applicable to the resource recovery treatment of complex wastewater with high ionic strength, high salt content, and high organic matter content, exhibiting not only good operational stability and economy, but also a high salt recovery rate.

[0101] The following examples further illustrate the resource-based treatment of wastewater with high salinity and high organic content using the resource-based treatment process of the present invention.

[0102] The main water quality analysis methods involved in the following examples are described below:

[0103] According to GB / T 30902-2014, inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine the content of elements such as calcium, magnesium, and silicon in samples. The instrument model was Spectro Arcos, and the test conditions were 1400W power and 0.8 mL / min nebulizer flow rate. -1 Plasma gas flow rate: 1.0 mL / min -1 .

[0104] According to GB / T 14642-2009, the content of anions such as fluoride and sulfate in samples was determined by ion chromatography. The instrument model was Integrion HPIC, and the test conditions were: eluent 30 mM and flow rate 1.0 mL / min. -1 Run time 15 min, injection volume 25 μL.

[0105] The suspended solids content was determined according to the gravimetric method for the determination of suspended solids in water, GB11901-1989.

[0106] Example 1:

[0107] The relevant parameter information for the high-salinity, high-organic-content wastewater in this embodiment is shown in Table 1. The wastewater treatment capacity in this embodiment is 100 L / h. The high-salinity, high-organic-content wastewater in this embodiment contains organic matter (long-chain alkanes, heterocyclic or polycyclic aromatic hydrocarbons, etc.) that are difficult to completely degrade by advanced oxidation technologies.

[0108] See the resource processing system used. Figure 1 As shown, the bipolar membrane electrodialysis device involved is referred to [reference needed]. Figure 2 As shown. The steps and system for resource recovery methods are described above and will not be repeated here.

[0109] The process steps include:

[0110] 1) The wastewater (with a salt content of about 15.4 wt%) was sent to the softening coagulation sedimentation unit for coagulation sedimentation to remove calcium ions, magnesium ions, silicon, fluoride ions and some organic matter from the wastewater, to obtain product water I (see Table 1 for water quality). In product water I, iron ions <0.1 mg / L and manganese ions <0.1 mg / L.

[0111] The softening coagulation and sedimentation unit employs a three-stage softening coagulation and sedimentation sub-unit. The first-stage softening coagulation and sedimentation sub-unit involves sequentially adding 5.44 g / L calcium hydroxide, 28 mg / L polyferric sulfate, and 1 mg / L polyamide, with a reaction time of 20 min and a residence time of 40 min. The second-stage softening coagulation and sedimentation sub-unit involves sequentially adding 3.88 g / L sodium carbonate, 28 mg / L polyferric sulfate, and 1 mg / L polyamide, with a reaction time of 30 min and a residence time of 50 min. The third-stage softening coagulation and sedimentation sub-unit involves sequentially adding 800 mg / L polyaluminum sulfate and 1 mg / L polyamide, with a reaction time of 30 min and a residence time of 50 min.

[0112] 2) Permeate I is fed into the ultrafiltration sub-unit of the ultrafiltration resin unit for ultrafiltration treatment. Then, the ultrafiltration treated water is passed into the resin sub-unit of the ultrafiltration resin unit for resin adsorption. After ultrafiltration treatment and resin adsorption, suspended solids, solid particles and residual calcium and magnesium ions in permeate I are removed to obtain permeate II (see Table 1 for water quality). The iron ion concentration in permeate II is <0.1 mg / L and the manganese ion concentration is <0.1 mg / L.

[0113] Among them, the ultrafiltration subunit: the ultrafiltration membrane adopts Hangzhou Qiushi hollow fiber ultrafiltration membrane, the material is PVDF, and the membrane pore size is 20nm;

[0114] In the resin subunit: Dusheng CH-93 cationic chelating resin is used, with a residence time of 20 min. 3) Permeate II is sent to the organic matter retention unit, which uses a special nanofiltration membrane to treat permeate II. Organic matter enters the nanofiltration concentrate side (the water quality of the concentrate containing organic matter is shown in Table 1), while monovalent salts and most divalent salts enter the nanofiltration permeate side, resulting in permeate III with separated organic matter (the water quality is shown in Table 1).

[0115] The special nanofiltration membrane used is model LCRNF (from Zhejiang Meiyi Membrane Technology Co., Ltd., which can retain organic matter and has a retention rate of <5wt% for divalent salts, but does not retain monovalent salts). The organic matter retention unit uses two-stage special nanofiltration membranes to retain organic matter, with an operating pressure of 5 bar.

[0116] In this embodiment, the water recovery rate of the organic matter retention unit is 90%, and the organic matter retention rate is 75 wt% based on TOC (total organic carbon).

[0117] 4) The permeate III is sent to the advanced oxidation unit to degrade the organic matter remaining in permeate III, and permeate IV is obtained (see Table 1 for water quality information).

[0118] The advanced oxidation unit employs ozone catalytic oxidation, with a manganese-based catalyst (in this embodiment, the catalyst is Mn-CeOx / γ-Al2O3, where the molar ratio of Mn to Ce is 2:1, which can be prepared according to the preparation method in the literature "Research on Ozone Oxidation of Organic Pollutants by Manganese-based Catalyst, Journal of Dalian University of Technology, November 2021, Vol. 61, No. 6". In practical applications, other catalysts that can be used for advanced oxidation degradation of organic matter can also be used instead). The ozone dosage is 720 mg / L; based on TOC, the organic matter removal rate is 64.32%.

[0119] 5) The permeate IV was used as the raw solution to be treated and fed into the bipolar membrane electrodialysis unit (see...). Figure 2 Electrodialysis is performed to obtain acid solution, alkaline solution and desalinated water;

[0120] Specifically, the permeate IV from the advanced oxidation unit is introduced as the raw solution to be treated into the salt chamber 8 of the bipolar membrane electrodialysis unit for bipolar membrane electrodialysis treatment. The current density of the bipolar membrane electrodialysis device is 800 A / m³. 2 The membrane surface flow rate is 4.5 cm / s, the electrode liquid is a 4% sodium hydroxide solution, and the thickness of the water distribution baffle is 3 mm.

[0121] The specific operation process of the bipolar membrane electrodialysis unit is described in the example above. The fresh circulating liquid introduced into the circulating liquid chamber 7 is a brine solution prepared according to the proportions of inorganic anions and cations in the permeate IV of the advanced oxidation unit. During operation, when the TOC of the circulating liquid in chamber 7 exceeds 75 mg / L, the circulating liquid is replaced with fresh liquid. The experiment is stopped when the salinity of the feed solution in the salt chamber 8 drops to 5%, and the current decreases significantly (by 8-10%) or the voltage increases significantly (by 8-10%).

[0122] In the bipolar membrane electrodialysis unit, the acid produced in acid chamber 6 and the sodium hydroxide produced in alkali chamber 9 are recovered, ultimately yielding 8% sodium hydroxide product and 8% mixed acid product. The current efficiency of the bipolar membrane electrodialysis unit reaches 85%.

[0123] 6) The desalinated water is fed into the membrane concentration unit. In this embodiment, the membrane concentration unit uses a disc tube high-pressure reverse osmosis (DTRO) device to concentrate the desalinated water. The operating pressure is 15 MPa and the treatment temperature is 35°C. After membrane concentration, concentrated water with TDS = 151500 mg / L (salt content of about 15.2 wt%) and permeate V are obtained. The recovery rate of permeate V is 64.29%. The concentrated water is transported back to the advanced oxidation unit in step 4) through pipeline to be treated with permeate III for organic matter degradation.

[0124] In this embodiment, the water quality analysis results of the process units corresponding to each step are shown in Table 1.

[0125] Table 1. Water quality analysis results for each process unit.

[0126]

[0127]

[0128] Calculate the process water recovery rate and process salt recovery rate using the following formulas.

[0129] Calculation formula:

[0130] (1) Process water recovery rate = water produced by organic matter retention unit / water produced by ultrafiltration resin unit. Note: Acids and alkalis prepared by bipolar membrane are reused.

[0131] (2) Process salt recovery rate = salt content of water produced by organic matter interception unit / salt content of water produced by ultrafiltration resin unit. Note: Bipolar membrane can convert almost all inorganic salts into acids and alkalis for reuse.

[0132] As can be seen from the above embodiments, the process of the present invention can realize the resource recovery of high-salt and high-organic-content wastewater, with a process water recovery rate of 90%; the process salt recovery rate is 89.72% based on TDS; the prepared acid is a mixed acid of hydrochloric acid and sulfuric acid with a mass fraction of 8% and a TOC of 3 mg / L; the prepared alkali is sodium hydroxide with a mass fraction of 8% and a TOC of 2 mg / L. The system operates stably for 200 hours, and the current efficiency of the bipolar membrane electrodialysis unit remains stable at 85%, with stable concentrations of acid and alkali and TOC content.

[0133] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A resourceful treatment process of high salinity high organic content wastewater, characterized in that, Includes the following steps: 1) The wastewater is sent to a softening coagulation sedimentation unit for coagulation sedimentation to remove calcium ions, magnesium ions, fluoride ions and / or silicon contained in the wastewater, as well as to remove some organic matter, to obtain product water I; the wastewater contains organic matter that cannot be degraded by advanced oxidation. 2) The product water I is fed into an ultrafiltration resin unit for ultrafiltration and resin adsorption in sequence to remove suspended solids, solid particles and residual calcium and / or magnesium ions in the product water I to obtain product water II. 3) The permeate II is fed into the organic matter retention unit to retain the organic matter in the permeate II, resulting in a saline stream of permeate III from which the organic matter has been separated; the permeate II is treated by a special nanofiltration membrane in the organic matter retention unit, wherein the special nanofiltration membrane is a nanofiltration membrane that can retain organic matter, has a retention rate of <5wt% for divalent salts and does not retain monovalent salts; 4) The permeate III is fed into an advanced oxidation unit to degrade the residual organic matter in the permeate III, yielding permeate IV; 5) The product water IV is sent as the raw solution to be treated into the bipolar membrane electrodialysis unit for electrodialysis to obtain acid solution, alkaline solution and desalinated fresh water; 6) The desalinated water is fed into a membrane concentration unit, where it is concentrated to obtain concentrate and permeate V; the concentrate is returned to the advanced oxidation unit in step 4); and the permeate V is reused as wastewater. In step 5), the bipolar membrane electrodialysis unit uses a bipolar membrane electrodialysis device for electrodialysis. The bipolar membrane electrodialysis device includes an anode plate, a membrane stack, and a cathode plate arranged sequentially. The membrane stack includes a first bipolar membrane and one or more membrane units. The first bipolar membrane is adjacent to the cathode plate. The membrane units are disposed between the first bipolar membrane and the anode plate. When multiple membrane units exist, they are sequentially spaced between the first bipolar membrane and the anode plate. Each membrane unit includes a second bipolar membrane, a first anion exchange membrane, a second anion exchange membrane, a first cation exchange membrane, and a second cation exchange membrane arranged sequentially from the anode plate to the cathode plate. The second bipolar membrane of the membrane unit adjacent to the anode plate is positioned between the anode plate and the cathode plate, and the cathode plate is positioned between the anode plate and the cathode plate. Each of the first bipolar membranes forms an electrode chamber; in each membrane unit, an acid chamber is formed between the second bipolar membrane and the first anion exchange membrane; a circulating liquid chamber is formed between the first anion exchange membrane and the second anion exchange membrane, and between the first cation exchange membrane and the second cation exchange membrane; a salt chamber is formed between the second anion exchange membrane and the first cation exchange membrane, the salt chamber having a salt chamber inlet for inputting the raw solution to be treated and a salt chamber outlet for outputting desalinated fresh water; an alkali chamber is formed between the second cation exchange membrane of the membrane unit adjacent to the first bipolar membrane and the first bipolar membrane; when multiple membrane units exist, in the direction from the anode plate to the cathode plate, an alkali chamber is formed between the second cation exchange membrane of the preceding membrane unit and the second bipolar membrane of the adjacent following membrane unit; In step 5), the raw solution to be treated is introduced into the salt chamber through the salt chamber inlet, the electrode liquid is introduced into the electrode chamber, the circulating liquid is introduced into the circulating liquid chamber, and deionized water is introduced into the acid chamber and the alkali chamber; through the electrodialysis, the acid solution and the alkali solution are generated in the acid chamber and the alkali chamber respectively, and the desalinated fresh water is obtained in the salt chamber.

2. The process according to claim 1, characterized in that, The high-salinity, high-organic-content wastewater has a salt content of over 8 wt% and a TOC content of over 100 mg / L. The high-salinity, high-organic-content wastewater contains monovalent and / or divalent salts, and the product water III in step 3) is a saline stream containing monovalent and / or divalent salts.

3. The process according to claim 2, characterized in that, The high-salinity, high-organic-content wastewater has a salt content of 8wt%-20wt% and a TOC of 100-1500mg / L.

4. The process according to claim 3, characterized in that, The salt content of the high-salinity, high-organic-content wastewater is 10-18 wt%.

5. The process according to any one of claims 1-2, characterized in that, The organic matter retention unit includes multiple stages of the special nanofiltration membrane, and the organic matter retention unit has an organic matter retention rate of 65-85 wt%.

6. The process according to any one of claims 1-2, characterized in that, The number of membrane units is two or more.

7. The process according to claim 6, characterized in that, The number of membrane units is ≤100.

8. The process according to any one of claims 1-2, characterized in that, In the membrane unit, one or more anion exchange membranes are provided between the first anion exchange membrane and the second anion exchange membrane; a circulating liquid chamber is formed between each adjacent anion exchange membrane; And / or, one or more cation exchange membranes are further provided between the first cation exchange membrane and the second cation exchange membrane; a circulating liquid chamber is formed between each adjacent cation exchange membrane.

9. The process according to claim 1 or 2, characterized in that, The circulating liquid is a brine prepared in equal proportions based on the inorganic anionic and cationic components of the permeate IV of the advanced oxidation unit.

10. The process according to claim 9, characterized in that, When the TOC value of the circulating liquid in the circulating liquid chamber is 0.8-1.6 times the TOC value of the permeate IV of the advanced oxidation unit, replace it with fresh circulating liquid.

11. The process according to any one of claims 1-2, characterized in that, The acid and / or alkaline solution obtained in step 5) are used for the regeneration of the resin in the ultrafiltration resin unit, or as a pH adjuster in the wastewater treatment process.

12. The process according to any one of claims 1-2, characterized in that, In step 1), the softening coagulation sedimentation unit includes one or more softening coagulation sedimentation sub-units arranged in series. And / or, in step 2), the ultrafiltration membrane in the ultrafiltration resin unit is selected from one or more combinations of organic ultrafiltration membranes and inorganic ceramic membranes, and the resin in the ultrafiltration resin unit is a cationic chelating resin; And / or, in step 4), the oxidation process used in the advanced oxidation unit is selected from one or more combinations of ozone oxidation, ozone catalytic oxidation, Fenton oxidation, electrocatalytic oxidation, ozone-co-Fenton oxidation, and ozone-co-UV oxidation processes.

13. The process according to any one of claims 1-2, characterized in that, In step 1), the permeate I obtained after treatment by the softening coagulation sedimentation unit has the following composition: calcium ions < 10 mg / L, magnesium ions < 2 mg / L, iron ions < 0.1 mg / L, manganese ions < 0.1 mg / L, silicon < 5 mg / L, fluoride ions < 15 mg / L, suspended solids < 100 mg / L, and organic matter removal rate of 8~10 wt%. And / or, in step 2), the permeate II obtained after treatment by the ultrafiltration resin unit has the following composition: calcium ions < 1 mg / L, magnesium ions < 1 mg / L, iron ions < 0.1 mg / L, manganese ions < 0.1 mg / L, silicon < 2 mg / L, fluoride ions < 15 mg / L, suspended solids ≤ 0.1 mg / L, and organic matter removal rate of 3~5 wt%; And / or, in step 3), the organic matter retention unit has a retention rate of 65-85 wt% for organic matter. And / or, in step 4), the advanced oxidation unit achieves a removal rate of 50-70 wt% for organic matter. And / or, in step 6), the salt content of the concentrated water is 12 wt% or more; And / or, in step 6), the desalinated freshwater is treated by the membrane concentration unit, and the recovery rate of permeate V is 40-75% (v / v).

14. The process according to claim 13, characterized in that, In step 6), the salt content of the concentrated water is 12wt%-18wt%.

15. A resource-based treatment system for wastewater with high salinity and high organic content, characterized in that, include: A softening coagulation sedimentation unit is used to treat the wastewater to remove calcium ions, magnesium ions, fluoride ions and / or silicon contained therein, as well as to remove some organic matter, and to obtain product water I. An ultrafiltration resin unit is used to sequentially treat the permeate I from the softening coagulation sedimentation unit with ultrafiltration and resin adsorption to remove suspended solids, solid particles, and residual calcium and / or magnesium ions, and obtain permeate II. An organic matter rejection unit is used to reject organic matter from the permeate II from the ultrafiltration resin unit to obtain permeate III from which organic matter has been separated; the organic matter rejection unit includes a special nanofiltration membrane, which is a nanofiltration membrane that can reject organic matter, has a rejection rate of <5wt% for divalent salts and does not reject monovalent salts. An advanced oxidation unit is used to degrade the organic matter remaining in the product water III to obtain product water IV; A bipolar membrane electrodialysis unit is used to electrodialyze the permeate IV from the advanced oxidation unit as the raw solution to be treated, in order to obtain acid solution, alkaline solution and desalinated fresh water. A membrane concentration unit is used to concentrate the desalinated water using a membrane to obtain concentrated water and permeate V, and to return the concentrated water to the advanced oxidation unit. The bipolar membrane electrodialysis unit includes a bipolar membrane electrodialysis device, which includes an anode plate, a membrane stack, and a cathode plate arranged sequentially. The membrane stack includes a first bipolar membrane and one or more membrane units. The first bipolar membrane is adjacent to the cathode plate, and the membrane units are disposed between the first bipolar membrane and the anode plate. When there are multiple membrane units, the multiple membrane units are arranged sequentially and spaced apart between the first bipolar membrane and the anode plate. The membrane unit includes a second bipolar membrane, a first anion exchange membrane, a second anion exchange membrane, a first cation exchange membrane, and a second cation exchange membrane, which are arranged sequentially at intervals from the anode plate to the cathode plate. An electrode chamber is formed between the second bipolar membrane of the membrane unit adjacent to the anode plate and the anode plate, and between the cathode plate and the first bipolar membrane; In the membrane unit, an acid chamber is formed between the second bipolar membrane and the first anion exchange membrane; A circulating liquid chamber is formed between the first anion exchange membrane and the second anion exchange membrane, and between the first cation exchange membrane and the second cation exchange membrane, respectively; A salt chamber is formed between the second anion exchange membrane and the first cation exchange membrane. The salt chamber is provided with a salt chamber inlet for inputting the raw solution to be treated and a salt chamber outlet for outputting the desalinated fresh water. An alkaline chamber is formed between the second cation exchange membrane of the membrane unit adjacent to the first bipolar membrane and the first bipolar membrane; When multiple membrane units are present, an alkaline chamber is formed between the second cation exchange membrane of the preceding membrane unit and the second bipolar membrane of the adjacent following membrane unit in the direction from the anode plate to the cathode plate.

16. The resource recovery system according to claim 15, characterized in that, The organic matter retention unit includes multiple stages of the aforementioned special nanofiltration membranes.

17. The resource recovery system according to claim 15, characterized in that, The number of membrane units is two or more.

18. The resource recovery system according to claim 17, characterized in that, The number of membrane units is ≤100.

19. The resource recovery system according to claim 17, characterized in that, In the membrane unit, one or more anion exchange membranes are provided between the first anion exchange membrane and the second anion exchange membrane; a circulating liquid chamber is formed between each adjacent anion exchange membrane; And / or, one or more cation exchange membranes are further provided between the first cation exchange membrane and the second cation exchange membrane; a circulating liquid chamber is formed between each adjacent cation exchange membrane.

20. The resource recovery system according to any one of claims 17-19, characterized in that, The bipolar membrane electrodialysis unit also includes a salt chamber feed solution circulation device, an electrode solution circulation device, an alkali solution circulation device, an acid solution circulation device, and a circulating liquid circulation device. The inlet of the salt chamber liquid circulation device is connected to the outlet of the salt chamber, and the outlet of the salt chamber liquid circulation device is connected to the inlet of the salt chamber, so that the liquid in the salt chamber forms a circulating flow between the salt chamber and the salt chamber liquid circulation device; The inlet of the polar liquid circulation device is connected to the outlet of the polar chamber, and the outlet of the polar liquid circulation device is connected to the inlet of the polar chamber, so that the polar liquid in the polar chamber forms a circulating flow between the polar chamber and the polar liquid circulation device; The inlet of the alkali circulation device is connected to the outlet of the alkali chamber, and the outlet of the alkali circulation device is connected to the inlet of the alkali chamber, so that the liquid in the alkali chamber forms a circulating flow between the alkali chamber and the alkali circulation device. The inlet of the acid circulation device is connected to the outlet of the acid chamber, and the outlet of the acid circulation device is connected to the inlet of the acid chamber, so that the liquid in the acid chamber forms a circulating flow between the acid chamber and the acid circulation device. The inlet of the circulating fluid circulation device is connected to the outlet of the circulating fluid chamber, and the outlet of the circulating fluid circulation device is connected to the inlet of the circulating fluid chamber, so that the circulating fluid in the circulating fluid chamber forms a circulating flow between the circulating fluid chamber and the outlet of the circulating fluid circulation device.

21. The resource recovery system according to any one of claims 15-19, characterized in that, The ultrafiltration resin unit includes an ultrafiltration subunit and a resin subunit connected in series. The ultrafiltration membrane in the ultrafiltration subunit is selected from one or more combinations of organic ultrafiltration membranes and inorganic ceramic membranes. The resin in the resin subunit is a cation chelating resin.

22. The resource recovery system according to any one of claims 15-19, characterized in that, The resource recovery system is used to implement the resource recovery treatment process for high-salinity, high-organic-content wastewater as described in any one of claims 1-14.

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