Multi-resource recovery and treatment method and system for acidic salt-containing wastewater

Abstract

The present application relates to a kind of acid salt-containing wastewater multi-resource recycling processing method and system, first to acid salt-containing wastewater is diffused dialysis processing, then the recovery acid liquid and recovery salt liquid in it are respectively subjected to electrodialysis concentration processing, so that the acid in it can be effectively and fully extracted, to be able to be used as raw material extraction agent to return to raw material processing system for the extraction of raw material, realizes the sustainable utilization of waste acid resourceization;And the salt in wastewater can be converted into high-quality liquid fertilizer, directly used in farmland.Compared with the chemical, biological and other treatment methods in the prior art, the method and system in the present application realize multi-resource recycling, for example, the total nitrogen recovery rate in acid ammonium salt-containing wastewater is as high as 90%-95%.In addition, based on the method and system of the present application, the final effluent can reach the standard of reclaimed water reuse and industrial wastewater discharge, and the green industrial wastewater multi-resource efficient recovery can be realized.

Description

Technical Field

[0001] This invention relates to the field of acidic saline wastewater treatment technology, and particularly to a multi-resource recovery and treatment method and system for acidic saline wastewater. Background Technology

[0002] Acidic saline wastewater refers to industrial wastewater that is acidic and contains salt. Salt refers to a compound formed by the combination of metal ions or ammonium ions and acid radical ions. During the decomposition of salt, ammonium ions, ferrous salt ions, metal ions, etc. can be regarded as salt ions.

[0003] With the advancement of industrialization, industries such as electroplating, printing and dyeing, metallurgy, and chemicals (especially food chemicals) generate large amounts of the aforementioned acidic and saline wastewater. For example, pectin processing often employs acid extraction (such as nitric acid) and alcohol precipitation (such as ethanol) techniques. After adjusting the pH with nitric acid and ammonia, pectin wastewater retains high concentrations of nitrogen (ammonia nitrogen and nitrate nitrogen reaching thousands or even tens of thousands of milligrams per liter), waste acid, and effluent resources. This type of wastewater seriously threatens the ecological environment. Biological treatment methods consume large amounts of reagents and energy, have poor nitrogen removal efficiency, and result in significant waste of waste acid, nitrogen, and water resources.

[0004] In existing technologies, the aforementioned acidic and saline wastewater is typically discharged directly, lacking a method and system for recovering and treating its various resource elements. Therefore, resource-based treatment technologies for this type of industrial water urgently need to be researched. Summary of the Invention

[0005] In view of this, the present invention provides a method and system for multi-resource recovery and treatment of acidic saline wastewater, which can recover and recycle the acid and ammonium salts contained in the acidic saline wastewater, thereby avoiding water pollution caused by the processed water.

[0006] The first aspect of this invention discloses a method for multi-resource recovery and treatment of acidic saline wastewater, comprising:

[0007] Step S1: The acidic saline wastewater is subjected to diffusion dialysis treatment, so that hydrogen ions and acid radical ions enter the dialysis liquid to form diffusion dialysis acid solution, while salt ions are retained in the diffusion residue.

[0008] Step S2: The recovered acid solution is subjected to electrodialysis acid concentration treatment to obtain concentrated acid solution and acid concentration treatment effluent, wherein the recovered acid solution includes the diffusion dialysis acid solution obtained according to step S1; and the recovered salt solution is subjected to electrodialysis salt concentration treatment to obtain concentrated salt solution and salt concentration treatment effluent, wherein the recovered salt solution includes the diffusion residue containing ammonium ions obtained according to step S1.

[0009] Step S3: The concentrated acid solution obtained from the electrodialysis concentrated acid treatment in step S2 is used as a pectin extraction agent and back-input into the pectin processing system for pectin extraction.

[0010] The acidic saline wastewater of this invention is pectin processing wastewater generated during pectin processing. This wastewater is produced after adjusting the pH with nitric acid and ammonia water using acid extraction (e.g., nitric acid) and alcohol precipitation (e.g., ethanol) techniques during pectin processing, resulting in a nitric acid-ammonium nitrate mixed system. In this case, the salt ion is ammonium ion (NH4+). + The method of this invention enables the separation, purification, and concentration of acid (hydrogen ions) and ammonia (ammonium ions) in pectin processing wastewater, as well as water desalination.

[0011] Specifically, in step S1, pure water is used as the dialysis liquid to perform diffusion dialysis treatment on the pretreated acidic saline wastewater (e.g., pectin processing wastewater). Salt ions and impurities are retained in the diffusion liquid, while hydrogen ions (H+) are retained in the dialysis liquid. + Due to its small hydration radius and special transport mechanism in aqueous solution, it can pass through anion exchange membrane with acid radicals into the dialysis solution, while salt ions (such as ammonium ions) are retained, thereby achieving acid-salt separation.

[0012] In step S2, the recovered acid solution includes the diffusion dialysis acid solution obtained in step S1, and the recovered salt solution includes the diffusion residue containing salt ions obtained in step S1. Specifically, the diffusion dialysis acid solution and diffusion residue after diffusion dialysis separation are subjected to electrodialysis concentration treatment in a concentration chamber and a dilute chamber at a volume ratio of 1:20-1:10, respectively. That is, the diffusion dialysis acid solution is subjected to electrodialysis acid concentration treatment according to the aforementioned ratio to obtain concentrated acid solution, and the diffusion residue is subjected to electrodialysis salt concentration treatment to obtain concentrated salt solution. The so-called concentrated salt solution refers to the concentrated solution rich in salt ions after electrodialysis concentration of the diffusion residue after acid-salt separation. In the case that the acidic saline wastewater is pectin processing wastewater, the obtained concentrated salt solution is concentrated ammonium salt solution. During the concentration process, the ion exchange membrane has a secondary interception effect on impurities, thus ensuring the purity of the concentrated solution.

[0013] The concentrated acid solution obtained in step S2 can be directly fed back into the raw material processing system. Specifically, when the acidic saline wastewater is pectin processing wastewater, the obtained concentrated acid solution can be directly used in the processing system for extracting pectin from lemon peel pomace, thereby realizing the recycling of acid.

[0014] In the multi-resource recovery and treatment method for acidic saline wastewater disclosed in the first aspect of the present invention, after step S2 and before step S3, the method further includes:

[0015] Step A1: The obtained acid concentration effluent is subjected to reverse osmosis treatment to obtain reverse osmosis effluent I and reverse osmosis concentrated acid solution.

[0016] And / or, in step A2, the concentrated salt solution obtained in step S2 through the electrodialysis salt concentration treatment step is subjected to diffusion dialysis treatment again to perform re-deacidification, to obtain a secondary recovered acid solution containing residual acid radical ions and a further concentrated salt solution; in the case that the acidic saline wastewater is pectin processing wastewater, the obtained further concentrated salt solution is a further concentrated ammonium salt solution.

[0017] In step A3, the obtained reverse osmosis concentrated acid solution and / or secondary recycled acid solution are also included as part of the recycled acid solution and participate in the electrodialysis acid concentration treatment described in step S2.

[0018] Some acid remains in the acid concentrate effluent obtained after electrodialysis acid concentration treatment and the concentrated brine obtained after electrodialysis salt concentration treatment. Therefore, by using the above steps A1-A3, the acid concentrate effluent is subjected to reverse osmosis treatment and the concentrated brine is subjected to diffusion dialysis treatment again to obtain reverse osmosis concentrated acid solution and secondary recovered acid solution, respectively. These two are also included as part of the recovered acid solution, so that the reverse osmosis concentrated acid solution and the secondary recovered acid solution obtained after secondary treatment can be reintroduced into the electrodialysis acid concentration treatment to produce the final concentrated acid solution together with the diffusion dialysis acid solution. This can greatly improve the acid recovery rate.

[0019] In other words, in this invention, the recovered acid solution used for electrodialysis acid concentration is composed of at least one of diffusion dialysis acid solution, reverse osmosis concentrated acid solution, and secondary recovered acid solution. In a preferred embodiment, the recovered acid solution used for electrodialysis acid concentration is composed of diffusion dialysis acid solution, reverse osmosis concentrated acid solution, and secondary recovered acid solution. Those skilled in the art will understand that at the beginning of the method steps of this invention, only diffusion dialysis acid solution is used as the recovered acid solution for acid concentration; however, after steps A1 and A2, the diffusion dialysis acid solution, reverse osmosis concentrated acid solution, and secondary recovered acid solution are used together as the recovered acid solution for acid concentration.

[0020] In addition, the reverse osmosis treatment in step A1 not only allows the reverse osmosis concentrate to be used as part of the acid recovery solution to improve the acid recovery rate, but also enables the reverse osmosis effluent obtained after the reverse osmosis treatment to be directly discharged in compliance with standards or recycled within the plant.

[0021] In a preferred embodiment of the present invention, step A4 is further included, in which the reverse osmosis effluent I obtained in step A1 is returned to the diffusion dialysis treatment of acidic saline wastewater in step S1, and used as part of the dialysis solution. That is, the reverse osmosis effluent obtained after reverse osmosis treatment can be reused as dialysis solution to achieve recycling in the method of the present invention.

[0022] The above process not only avoids water pollution caused by the effluent, but also realizes the sustainable utilization of waste acid as a resource.

[0023] According to the first aspect of the present invention, the method for multi-resource recovery and treatment of acidic saline wastewater includes, after the step of electrodialysis acid concentration treatment of the recovered acid solution in step S2, a further step B1, performing reverse osmosis treatment on the obtained salt concentration effluent to obtain reverse osmosis effluent II and reverse osmosis concentrated brine; and a step B2, using the obtained reverse osmosis concentrated brine as part of the recovered brine solution, participating in the electrodialysis salt concentration treatment described in step S2. The so-called reverse osmosis concentrated brine refers to a concentrated solution containing salt ions after reverse osmosis treatment. In the case of acidic saline wastewater being pectin processing wastewater, the salt ions are ammonium ions, and the obtained reverse osmosis concentrated brine is a reverse osmosis concentrated ammonium salt solution.

[0024] Furthermore, the diffusion residue obtained after diffusion dialysis in step S1 may still be acidic after electrodialysis salt concentration. Therefore, based on step A2, diffusion dialysis is used to recover the acid again. The recovered acid can be used as part of the recovered acid to enter the electrodialysis acid concentration treatment, and the residue at this time (i.e., the further concentrated salt solution) can be used as high-quality liquid fertilizer. For example, in the case of acidic saline wastewater being pectin processing wastewater, after diffusion dialysis in step A2, the further concentrated salt solution becomes a further concentrated ammonium salt solution, which can be used as high-quality liquid nitrogen fertilizer directly in farmland. The effluent after desalination treatment by electrodialysis salt concentration can also be treated by reverse osmosis in step B1 to obtain reverse osmosis effluent and reverse osmosis concentrated salt solution. The reverse osmosis concentrated salt solution can still enter the electrodialysis salt concentration treatment step, that is, participate in the electrodialysis salt concentration treatment in step S2 as part of the recovered salt solution.

[0025] Furthermore, the reverse osmosis treatment in step B1 not only allows the concentrated reverse osmosis brine to be used as part of the recovered brine to improve the recovery rate of salt (e.g., ammonium salt), but also enables the reverse osmosis effluent obtained after the reverse osmosis treatment to be directly discharged in compliance with standards or recycled within the plant.

[0026] In a preferred embodiment of the present invention, step B3 is further included, in which the obtained reverse osmosis effluent II is returned to the diffusion dialysis treatment of pectin processing wastewater in step S1, and used as part of the dialysis solution. That is, the reverse osmosis effluent II obtained after reverse osmosis treatment can be reused as dialysis solution to achieve recycling in the method of the present invention.

[0027] Compared to chemical and biological treatment methods, the acidic saline wastewater treatment method of this invention (e.g., pectin processing wastewater) achieves multi-resource recovery and utilization of nitrogen, with an overall nitrogen recovery rate as high as 90%-95%. Furthermore, its effluent meets the standards for reclaimed water reuse and industrial wastewater discharge, making it a zero-waste, green, and highly efficient multi-resource recovery method for pectin wastewater.

[0028] According to the first aspect of the present invention, the method for multi-resource recovery and treatment of acidic saline wastewater includes a step S0 before step S1, wherein the pectin processing wastewater is pretreated, and the pretreatment includes at least filtering the acidic saline wastewater.

[0029] A second aspect of this invention discloses a multi-resource recovery and treatment system for acidic saline wastewater, comprising:

[0030] Diffusion dialysis membrane stack I uses dialysis solution to treat acidic saline wastewater through diffusion dialysis, so that hydrogen ions and acid radical ions enter the dialysis solution to form diffusion dialysis acid solution, while salt ions (such as ammonium ions) are retained in the diffusion residue solution.

[0031] Electrodialysis membrane stack I, which uses an acid concentration electrode solution to perform electrodialysis acid concentration treatment on the recovered acid solution to obtain concentrated acid solution and acid-concentrated effluent, wherein the recovered acid solution includes the diffusion dialysis acid solution obtained based on diffusion dialysis membrane stack I;

[0032] Electrodialysis membrane stack II uses an ammonium salt concentration electrode solution to perform electrodialysis salt concentration treatment on the recovered brine to obtain concentrated brine and effluent after salt concentration treatment, wherein the recovered brine includes a diffusion residue containing salt ions obtained based on diffusion dialysis membrane stack I.

[0033] According to the acidic saline wastewater multi-resource recovery and treatment system disclosed in the second aspect of the present invention, it further includes:

[0034] Reverse osmosis membrane stack I, which can perform reverse osmosis treatment on the acid concentrate effluent obtained based on electrodialysis membrane stack I to obtain reverse osmosis effluent I and reverse osmosis concentrated acid solution;

[0035] And / or diffusion dialysis membrane stack II, which is capable of diffusion dialysis treatment of concentrated brine obtained based on electrodialysis membrane stack II for re-deacidification to obtain secondary recovered acid solution including residual acid radical ions and further concentrated brine solution.

[0036] The recovered acid solution also includes the concentrated acid solution after reverse osmosis and / or the secondary recovered acid solution.

[0037] According to the acidic saline wastewater multi-resource recovery and treatment system disclosed in the second aspect of the present invention, the reverse osmosis effluent I obtained based on the reverse osmosis membrane stack I can be used as part of the dialysis solution used for diffusion dialysis treatment by the diffusion dialysis membrane stack I.

[0038] According to the acidic saline wastewater multi-resource recovery and treatment system disclosed in the second aspect of the present invention, it further includes a reverse osmosis membrane stack II, which is capable of reverse osmosis treatment of the effluent obtained after salt concentration treatment based on the electrodialysis membrane stack II to obtain reverse osmosis effluent II and reverse osmosis concentrated brine; the reverse osmosis concentrated brine can participate in the electrodialysis salt concentration treatment based on the electrodialysis membrane stack II as part of the recovered brine.

[0039] According to the acidic saline wastewater multi-resource recovery and treatment system disclosed in the second aspect of the present invention, the reverse osmosis effluent II obtained based on the reverse osmosis membrane stack II can be used as part of the dialysis solution used for diffusion dialysis treatment by the diffusion dialysis membrane stack I.

[0040] The acidic saline wastewater multi-resource recovery and treatment system disclosed in the second aspect of the present invention further includes a pretreatment device capable of pretreating pectin processing wastewater before diffusion dialysis treatment based on diffusion dialysis membrane stack I; the pretreatment device includes at least a filter element for filtering the acidic saline wastewater.

[0041] The implementation process of the above system is explained using pectin processing wastewater as acidic and saline wastewater: The pectin processing wastewater flowing out of the pectin processing system is first pretreated by a pretreatment device, including at least filtration pretreatment by a filter element. The pretreated pectin processing wastewater is used as the diffusion liquid, and pure water is used as the dialysis liquid. The two are then subjected to diffusion dialysis treatment through diffusion dialysis membrane stack I. The diffusion liquid and dialysis liquid are fed in in a cross-flow manner. The outflow liquids are diffusion dialysis acid and diffusion residue, respectively. Correspondingly, a first liquid tank for receiving and recovering acid (including diffusion dialysis acid) and a second liquid tank for receiving diffusion residue are respectively provided. Both the first and second liquid tanks are connected to the diffusion dialysis device. The diffusion dialysis acid solution obtained by diffusion dialysis is introduced into the concentration and dilute chambers of electrodialysis membrane stack I by a peristaltic pump at a volume ratio in the range of 1:20-1:10. A limiting current is applied to both sides of the electrodialysis membrane stack. When the conductivity of the dilute chamber (recovered acid solution) tends to stabilize or the pH changes drastically, electrodialysis stops, and the concentrated acid solution obtained in the concentration chamber is the concentrated acid solution.

[0042] The acid recovered from the concentration chamber of electrodialysis membrane stack I can be used as a pectin extraction agent and recycled back to the lemon pomace pectin extraction process.

[0043] During or after electrodialysis acid concentration treatment via electrodialysis membrane stack I, a diffusion residue mainly composed of salt (ammonium nitrate) enters the concentration and dilute chambers of electrodialysis membrane stack II at a volume ratio in the range of 1:20-1:10. The flow rate of the flow meter is adjusted to ensure that electrodialysis membrane stack II circulates at an appropriate flow rate. After electrodialysis membrane stack II has been running stably for a period of time, a limiting current is applied to both sides of electrodialysis membrane stack II. When the conductivity of the dilute chamber tends to stabilize or the pH changes drastically, the electrodialysis reaction stops, thereby obtaining concentrated brine and effluent after salt concentration treatment.

[0044] The concentrated brine obtained by the electrodialysis membrane stack II contains some acid. Therefore, diffusion dialysis membrane stack II is used to perform diffusion dialysis to recover the acid. The recovered secondary acid solution can be processed into the first liquid tank and used as recovered acid solution for electrodialysis acid concentration treatment. The further concentrated brine obtained by diffusion dialysis membrane stack II can be used as high-quality liquid nitrogen fertilizer and can be directly applied to farmland.

[0045] The concentrated acid effluent obtained from the dilute chamber of electrodialysis membrane stack I can then enter reverse osmosis membrane stack I. The feed water temperature of reverse osmosis membrane stack I is adjusted until there are no air bubbles in the pipe and the flow meter reading tends to stabilize. Then, the reverse osmosis operating pressure is adjusted to 30-60 Bar. Finally, reverse osmosis effluent I and reverse osmosis concentrated acid solution are obtained. The reverse osmosis concentrated acid solution can also be used as recycled acid solution for electrodialysis acid concentration treatment to obtain the final concentrated acid solution.

[0046] The concentrated ammonium salt effluent obtained from the dilute chamber of electrodialysis membrane stack II can enter reverse osmosis membrane stack II for reverse osmosis treatment, resulting in reverse osmosis effluent II and reverse osmosis concentrated brine. The reverse osmosis ammonium salt solution can be used as part of the recovered brine to participate in the electrodialysis salt concentration treatment based on electrodialysis membrane stack II, while the reverse osmosis effluent II can be used as part of the dialysis solution used in diffusion dialysis treatment by diffusion dialysis membrane stack I.

[0047] In a preferred embodiment, electrodialysis membrane stack I and electrodialysis membrane stack II are the same unit, capable of first performing electrodialysis acid concentration treatment, followed by electrodialysis salt concentration treatment. Of course, those skilled in the art will understand that electrodialysis membrane stack I and electrodialysis membrane stack II can also be configured as two separate units.

[0048] Beneficial Effects: In the multi-resource recovery and treatment method and system for acidic saline wastewater of the present invention, the acid can be effectively and fully extracted so that it can be returned to the raw material processing system as a raw material extraction agent for raw material extraction, realizing the sustainable resource utilization of waste acid; moreover, the salt in the wastewater can be converted into high-quality liquid fertilizer for direct use in farmland. Compared with existing chemical and biological treatment methods, the method and system of the present invention achieve multi-resource recovery and utilization, for example, the overall nitrogen recovery rate in acidic ammonium salt wastewater is as high as 90%-95%. In addition, based on the method and system of the present invention, the final effluent can meet the standards for reclaimed water reuse and industrial wastewater discharge, achieving efficient multi-resource recovery of industrial wastewater with zero waste and green practices.

[0049] The following describes in detail the multi-resource recovery and treatment method and system for acidic saline wastewater of the present invention, with reference to the embodiments shown in the accompanying drawings and the reference numerals. Attached Figure Description

[0050] Figure 1 A flowchart of the multi-resource recovery and treatment method for acidic saline wastewater in this invention is shown, wherein the acidic saline wastewater is taken as an example of pectin processing wastewater of a nitric acid-ammonium nitrate mixed system.

[0051] Figure 2 A framework diagram of the multi-resource recovery and treatment system for acidic saline wastewater in this invention is shown.

[0052] Figure Labels

[0053] 1. Diffusion dialysis membrane stack I; 2. Acidic saline wastewater 2; 3. Recovered acid solution; 4. Diffusion residue; 5. Dialysate; 6. Peristaltic pump; 7. Electrode solution; 8. Concentrated acid solution; 9. Concentrated brine solution; 10. Electrodialysis membrane stack I; 10a. Electrodialysis membrane stack II; 11. DC power supply; 12. Further concentrated brine solution; 13. High-pressure pump; 14. Reverse osmosis membrane stack I; 14a. Reverse osmosis membrane stack II; 15. Reverse osmosis effluent I; 15a. Reverse osmosis effluent II. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0055] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0056] Figure 1A flowchart of the multi-resource recovery and treatment method for acidic saline wastewater in this invention is shown, wherein the acidic saline wastewater is taken as an example of pectin processing wastewater of a nitric acid-ammonium nitrate mixed system.

[0057] Combination Figure 1 As shown, the first embodiment of the present invention discloses a multi-resource recovery and treatment method for acidic saline wastewater, which includes:

[0058] Step S1: The acidic saline wastewater 2 (i.e., pectin processing wastewater in a nitric acid-ammonium nitrate mixed system) is subjected to diffusion dialysis treatment, so that hydrogen ions and acid radical ions enter the dialysis liquid 5 to form diffusion dialysis acid liquid, and salt ions are retained in the diffusion residue liquid 4; taking pectin processing wastewater as an example, the salt ions at this time are ammonium ions.

[0059] Step S2: The recovered acid solution 3 is subjected to electrodialysis acid concentration treatment to obtain concentrated acid solution 8 and acid concentration treatment effluent, wherein the recovered acid solution 3 includes the diffusion dialysis acid solution obtained according to step S1; and the recovered salt solution is subjected to electrodialysis salt concentration treatment to obtain concentrated salt solution 9 and salt concentration treatment effluent, wherein the recovered salt solution includes the diffusion residue 4 containing ammonium ions obtained according to step S1; taking pectin processing wastewater as an example, the recovered salt solution at this time is the recovered ammonium salt solution;

[0060] Step S3: The concentrated acid solution 8 obtained from the electrodialysis concentrated acid treatment in step S2 is used as a pectin extraction agent and back-transported into the pectin processing system for pectin extraction.

[0061] By means of the method of the present invention, the acidic saline wastewater 2 of the present invention can achieve separation, purification and concentration of acid (hydrogen ions) and ammonia (ammonium ions) as well as desalination of water resources.

[0062] Specifically, in step S1, pure water is used as the dialysis liquid 5 to perform diffusion dialysis treatment on the pretreated acidic saline wastewater 2. Salt ions and impurities are retained in the diffusion liquid, while hydrogen ions (H+) are retained in the dialysis liquid. + Due to their small hydration radius and unique transport mechanism in aqueous solutions, acid radicals pass through anion exchange membranes into the dialysis solution, while salt ions, such as ammonium ions (NH4+), pass through the anion exchange membrane into the dialysis solution. + The acid and salt are intercepted, thereby achieving the separation of acid and salt.

[0063] In step S2, the recovered acid solution 3 includes the diffusion dialysis acid solution obtained in step S1, and the recovered salt solution includes the diffusion residue 4 containing ammonium ions obtained in step S1. Specifically, the diffusion dialysis acid solution and diffusion residue 4, after diffusion dialysis separation, are subjected to electrodialysis concentration treatment in a concentration chamber and a dilute chamber at a volume ratio of 1:20-1:10, respectively. That is, the diffusion dialysis acid solution is subjected to electrodialysis acid concentration treatment according to the aforementioned ratio to obtain concentrated acid solution 8, and the diffusion residue 4 is subjected to electrodialysis salt concentration treatment to obtain concentrated salt solution 9. During the concentration process, the ion exchange membrane has a secondary interception effect on impurities, thus ensuring the purity of the concentrated solution. Taking pectin processing wastewater as an example, the concentrated salt solution 9 at this time is a concentrated ammonium salt solution.

[0064] The concentrated acid solution 8 obtained in step S2 can be directly fed back into the pectin processing system. Specifically, it can be directly used in the processing system for extracting pectin from lemon peel pomace, thereby realizing the recycling of acid.

[0065] In the multi-resource recovery and treatment method for acidic saline wastewater 2 disclosed in the first embodiment of the present invention, after step S2 and before step S3, the method further includes:

[0066] Step A1: The obtained acid concentration effluent is subjected to reverse osmosis treatment to obtain reverse osmosis effluent I15 and reverse osmosis concentrated acid solution.

[0067] And / or, in step A2, the concentrated brine 9 obtained in step S2 through the electrodialysis salt concentration treatment is subjected to diffusion dialysis treatment again to perform re-deacidification, to obtain a secondary recovered acid solution containing residual acid radical ions and a further concentrated brine 12; taking pectin processing wastewater as an example, the further concentrated brine 12 at this time is a further concentrated ammonium salt solution.

[0068] In step A3, the obtained reverse osmosis concentrated acid solution and / or secondary recycled acid solution are also included as part of the recycled acid solution 3 and participate in the electrodialysis acid concentration treatment described in step S2.

[0069] Some acid remains in the acid concentrate effluent obtained after electrodialysis acid concentration treatment and the concentrated brine 9 obtained after electrodialysis salt concentration treatment. Therefore, by means of the above steps A1-A3, the acid concentrate effluent is subjected to reverse osmosis treatment and the concentrated brine 9 is subjected to diffusion dialysis treatment again to obtain reverse osmosis concentrated acid solution 8 and secondary recovered acid solution, respectively. These two are also included as part of the recovered acid solution 3, so that the reverse osmosis concentrated acid solution 8 and the secondary recovered acid solution obtained after secondary treatment can re-enter the electrodialysis acid concentration treatment and, together with the diffusion dialysis acid solution, produce the final concentrated acid solution 8. This can greatly improve the acid recovery rate.

[0070] In other words, in this invention, the recovered acid solution 3 used for electrodialysis acid concentration is composed of at least one of diffusion dialysis acid solution, reverse osmosis concentrated acid solution, and secondary recovered acid solution. In a preferred embodiment, the recovered acid solution 3 used for electrodialysis acid concentration is composed of diffusion dialysis acid solution, reverse osmosis concentrated acid solution, and secondary recovered acid solution. Those skilled in the art will understand that at the beginning of the method steps of this invention, only diffusion dialysis acid solution is used as the recovered acid solution 3 for acid concentration. When the method steps of this invention proceed to steps A1 and A2, the diffusion dialysis acid solution, reverse osmosis concentrated acid solution, and secondary recovered acid solution are used together as the recovered acid solution 3 for acid concentration.

[0071] In addition, the reverse osmosis treatment in step A1 not only allows the reverse osmosis concentrate to be used as part of the recovered acid solution 3 to improve the acid recovery rate, but also allows the reverse osmosis effluent obtained after the reverse osmosis treatment to be directly discharged in compliance with standards or recycled within the plant.

[0072] In a preferred embodiment of the present invention, step A4 is further included, in which the reverse osmosis effluent I15 obtained in step A1 is returned to the diffusion dialysis treatment of the acidic saline wastewater 2 in step S1, and used as part of the dialysis solution 5. That is, the reverse osmosis effluent obtained after reverse osmosis treatment can be reused as dialysis solution 5 to achieve recycling in the method of the present invention.

[0073] The above process not only avoids water pollution caused by the effluent, but also realizes the sustainable utilization of waste acid as a resource.

[0074] According to the first embodiment of the present invention, the method for multi-resource recovery and treatment of acidic saline wastewater 2 includes, after the step of electrodialysis acid concentration treatment of the recovered acid solution 3 in step S2, step B1, performing reverse osmosis treatment on the obtained salt concentration treatment effluent to obtain reverse osmosis effluent II15a and reverse osmosis concentrated brine; and step B2, using the obtained reverse osmosis concentrated brine as part of the recovered brine to participate in the electrodialysis salt concentration treatment in step S2.

[0075] Furthermore, the diffusion residue 4 obtained after diffusion dialysis in step S1 may still be acidic after electrodialysis salt concentration. Therefore, based on step A2, diffusion dialysis is used to recover the acid again. The recovered acid can be used as part of the recovered acid 3 in the electrodialysis acid concentration treatment. The residue at this time (i.e., the further concentrated salt solution 12) can be used as high-quality liquid nitrogen fertilizer, which can be directly used in farmland. The effluent after desalination treatment by electrodialysis salt concentration can also be treated by reverse osmosis in step B1 to obtain reverse osmosis effluent and reverse osmosis concentrated salt solution. The reverse osmosis concentrated salt solution can still enter the electrodialysis salt concentration treatment step, that is, participate in the electrodialysis salt concentration treatment in step S2 as part of the recovered salt solution.

[0076] Furthermore, the reverse osmosis treatment in step B1 not only allows the concentrated reverse osmosis brine to be used as part of the recovered brine to improve the recovery rate of ammonium salts, but also enables the reverse osmosis effluent obtained after the reverse osmosis treatment to be directly discharged in compliance with standards or recycled within the plant.

[0077] In a preferred embodiment of the present invention, step B3 is further included, in which the obtained reverse osmosis effluent II15a is returned to the diffusion dialysis treatment of the acidic saline wastewater 2 in step S1, and used as part of the dialysis solution 5. That is, the reverse osmosis effluent II15a obtained after reverse osmosis treatment can be reused as dialysis solution 5 to achieve recycling in the method of the present invention.

[0078] According to the first embodiment of the present invention, the method for multi-resource recovery and treatment of acidic saline wastewater 2 includes a step S0 before step S1, wherein the acidic saline wastewater 2 is pretreated, and the pretreatment includes at least filtering the acidic saline wastewater 2.

[0079] Taking acidic, saline wastewater from pectin processing as an example, the method of this invention allows for the effective and complete extraction of the acid, which can then be reused as a pectin extractant in the pectin processing system, achieving sustainable resource utilization of waste acid. Furthermore, the ammonium salts in the wastewater can be converted into high-quality liquid nitrogen fertilizer for direct application in farmland. Compared to existing chemical and biological treatment methods, the method and system of this invention achieve multi-resource recovery and utilization of nitrogen, with an overall nitrogen recovery rate as high as 90%-95%. In addition, based on the method and system of this invention, the final effluent meets the standards for reclaimed water reuse and industrial wastewater discharge, enabling efficient and waste-free green pectin wastewater multi-resource recovery.

[0080] Compared to chemical and biological treatment methods, taking acidic saline wastewater as an example of pectin processing wastewater, the acidic saline wastewater treatment method of this invention achieves multi-resource recovery and utilization of nitrogen, with an overall nitrogen recovery rate as high as 90%-95%. Furthermore, its effluent meets the standards for reclaimed water reuse and industrial wastewater discharge, making it a zero-waste, green, and highly efficient multi-resource recovery method for pectin wastewater.

[0081] Taking acidic saline wastewater as pectin processing wastewater as an example, the specific implementation process of the above method is as follows: Acidic saline wastewater 2 flowing out of the pectin processing system enters the comprehensive equalization tank through the alcohol tower process, and is pretreated by a security filter, which serves as a pretreatment device. The pore size of the security filter membrane is 5μm. The pretreated acidic saline wastewater 2 is used as the diffusion liquid, and pure water is used as the dialysis liquid 5 for diffusion dialysis treatment. The tangential flow velocity of the dialysis liquid 5 is adjusted to 1.73cm / min, and the tangential flow velocity ratio of the dialysis liquid 5 to the diffusion liquid is 1.2:1. The diffusion liquid and the dialysis liquid 5 are fed in in a cross-flow manner. The outflow liquids are diffusion dialysis acid solution and diffusion residue 4, respectively. Correspondingly, a first liquid tank for receiving and recovering acid solution 3 (including diffusion dialysis acid solution) and a second liquid tank for receiving diffusion residue 4 are respectively set up, wherein both the first liquid tank and the second liquid tank are connected to the diffusion dialysis device.

[0082] The diffusion dialysis acid solution obtained is pumped by peristaltic pump 6 into the concentration and dilute chambers of an electrodialysis device (e.g., the electrodialysis membrane stack mentioned in the second embodiment below) at a volume ratio of 1:10. A 50% limiting current is applied to both sides of the electrodialysis device. When the conductivity of the dilute chamber (recovered acid solution 3) tends to stabilize or the pH changes drastically, electrodialysis is stopped, and the solution obtained in the concentration chamber is the concentrated acid solution. The acid solution recovered from the concentration chamber of the electrodialysis device can be used as a pectin extraction agent and can be recycled back to the lemon pomace pectin extraction process.

[0083] The diffusion residue 4, mainly composed of salt (ammonium nitrate), enters the concentrated and dilute chambers of the electrodialysis device at a volume ratio of 1:10. The flow rate of the flow meter is adjusted so that the electrodialysis membrane stack II10a circulates at an appropriate flow rate. After the electrodialysis device has been running stably for a period of time, a limiting current of 50-70% is applied to both sides of the electrodialysis device. When the conductivity of the dilute chamber tends to stabilize or the pH changes drastically, the electrodialysis reaction stops to obtain concentrated brine 9 (i.e., concentrated ammonium brine) and effluent after salt concentration treatment.

[0084] The concentrated brine 9 obtained by the electrodialysis device contains some acid. Therefore, a diffusion dialysis step is used to perform diffusion dialysis to recover the acid. The recovered secondary acid solution can be processed into the first liquid tank and used as the recovered acid solution 3 for electrodialysis acid concentration treatment. The further concentrated brine 12 (i.e., the further concentrated ammonium salt solution) obtained by the second diffusion dialysis can be used as a high-quality liquid nitrogen fertilizer and can be directly applied to farmland.

[0085] The concentrated acid effluent obtained by electrodialysis can then undergo reverse osmosis treatment. The influent temperature of the reverse osmosis treatment is adjusted to 25°C. After the air bubbles in the tube are eliminated and the flow meter reading stabilizes, the reverse osmosis operating pressure is adjusted to 30-60 Bar. Finally, reverse osmosis effluent I15 and reverse osmosis concentrated acid solution are obtained. The reverse osmosis concentrated acid solution can also be used as recycled acid solution 3 for electrodialysis acid concentration treatment to obtain the final concentrated acid solution.

[0086] The ammonium salt concentrate obtained by electrodialysis can also be treated by reverse osmosis to obtain reverse osmosis effluent II15a and reverse osmosis concentrated brine. The reverse osmosis ammonium salt solution can be used as part of the recovered brine to participate in the electrodialysis salt concentration treatment step, and the reverse osmosis effluent II15a can be used as part of the dialysis solution 5 used in the diffusion dialysis treatment in step S1.

[0087] Figure 2 A framework diagram of the multi-resource recovery and treatment system for acidic saline wastewater 2 in this invention is shown, wherein the influent is represented by solid lines and the effluent is represented by dashed lines.

[0088] Combination Figure 2 As shown, the second embodiment of the present invention discloses a multi-resource recovery and treatment system for acidic saline wastewater, which includes:

[0089] The diffusion dialysis membrane stack I1 uses dialysis solution 5 to treat acidic saline wastewater 2 through diffusion dialysis. Hydrogen ions and acid radical ions enter the dialysis solution 5 to form a diffusion dialysis acid solution, while salt ions are retained in the diffusion residue solution 4.

[0090] Electrodialysis membrane stack I10, which uses acid concentration electrode liquid 7 to perform electrodialysis acid concentration treatment on recovered acid liquid 3 to obtain concentrated acid liquid 8 and acid-concentrated effluent, wherein the recovered acid liquid 3 includes the diffusion dialysis acid liquid obtained based on diffusion dialysis membrane stack I1.

[0091] Electrodialysis membrane stack II10a, which uses ammonium salt concentration electrode solution 7 to perform electrodialysis salt concentration treatment on the recovered brine to obtain concentrated brine solution 9 and effluent after salt concentration treatment, wherein the recovered brine solution includes diffusion residue 4 containing salt ions obtained based on diffusion dialysis membrane stack I1.

[0092] The acidic saline wastewater multi-resource recovery and treatment system disclosed in the second embodiment of the present invention further includes:

[0093] Reverse osmosis membrane stack I14 is capable of reverse osmosis treatment of the acid concentrate effluent obtained based on electrodialysis membrane stack I10 to obtain reverse osmosis effluent I15 and reverse osmosis concentrated acid solution.

[0094] And / or diffusion dialysis membrane stack II, which is capable of diffusion dialysis treatment of concentrated brine 9 obtained based on electrodialysis membrane stack II 10a to perform re-deacidification, and obtain secondary recovered acid solution including residual acid radical ions and further concentrated brine 12.

[0095] The recovered acid solution 3 also includes the concentrated acid solution after reverse osmosis and / or the secondary recovered acid solution.

[0096] In the above-described process, the concentrated acid solution after reverse osmosis and the secondary recovered acid solution are refluxed to merge with the diffusion dialysis acid solution, thereby jointly forming the recovered acid solution. In the system of this invention, the dialysis tank for containing the dialysis solution and the diffusion tank for containing the diffusion solution (i.e., wastewater) are respectively connected to the inlet of the diffusion dialysis membrane stack I1 to supply the dialysis solution and diffusion solution into the diffusion dialysis membrane stack I1, wherein the dialysis solution and diffusion solution are fed in in a cross-flow manner; the first tank for receiving the recovered acid solution (including the diffusion dialysis acid solution) and the second tank for receiving the diffusion residue are respectively connected to the outlet of the diffusion dialysis device to receive the diffusion dialysis acid solution and the diffusion residue; the first tank, the concentrated acid solution tank for receiving the concentrated acid solution, and the electrode solution tank for storing the electrode solution are all circulatedly connected to the electrodialysis membrane stack I10 to perform electrodialysis acid concentration on the diffusion dialysis acid solution. The process involves obtaining concentrated acid solution; a second liquid tank, a concentrated brine tank for receiving concentrated brine solution, and another electrode liquid tank for storing electrode solution are all connected in a loop to the electrodialysis membrane stack II 10a to concentrate the diffusion residue solution by electrodialysis to obtain concentrated brine solution; the concentrated brine tank for receiving concentrated brine solution and another dialysis liquid tank are connected to the corresponding inlet of the diffusion dialysis membrane stack II, and the corresponding outlet of the diffusion dialysis membrane stack II is connected to another concentrated brine tank for receiving further concentrated brine solution 12 and a recovery acid tank, so as to further diffuse dialysis and deacidify the concentrated brine solution obtained after electrodialysis membrane stack II 10a. The secondary recovery acid formed at this time flows into the recovery acid tank through the corresponding outlet of the diffusion dialysis membrane stack II.

[0097] According to the acidic saline wastewater 2 multi-resource recovery and treatment system disclosed in the second embodiment of the present invention, the reverse osmosis effluent I15 obtained based on the reverse osmosis membrane stack I14 can be used as part of the dialysis solution 5 used for diffusion dialysis treatment of the diffusion dialysis membrane stack I1.

[0098] The acidic saline wastewater 2 multi-resource recovery and treatment system disclosed in the second embodiment of the present invention further includes a reverse osmosis membrane stack II 14a, which is capable of performing reverse osmosis treatment on the effluent after salt concentration treatment obtained based on the electrodialysis membrane stack II 10a to obtain reverse osmosis effluent II 15a and reverse osmosis concentrated brine; the reverse osmosis concentrated brine can participate in the electrodialysis salt concentration treatment based on the electrodialysis membrane stack II 10a as part of the recovered brine.

[0099] According to the second embodiment of the present invention, the acidic saline wastewater 2 multi-resource recovery and treatment system is provided, wherein the reverse osmosis effluent 215a obtained based on the reverse osmosis membrane stack 214a can be used as part of the dialysis solution 5 used for diffusion dialysis treatment of the diffusion dialysis membrane stack 11.

[0100] The acidic saline wastewater 2 multi-resource recovery and treatment system disclosed in the second embodiment of the present invention further includes a pretreatment device, which can pretreat the acidic saline wastewater 2 before diffusion dialysis treatment based on diffusion dialysis membrane stack I1; the pretreatment device includes at least a filter element for filtering the acidic saline wastewater 2.

[0101] Taking acidic saline wastewater as pectin processing wastewater as an example, the specific implementation process of the above system is as follows: The acidic saline wastewater 2 flowing out of the pectin processing system is first pretreated by a security filter, wherein the pore size of the security filter membrane is 5μm. The pretreated acidic saline wastewater 2 is used as the diffusion liquid, and pure water is used as the dialysis liquid 5. The dialysis liquid is treated by diffusion dialysis membrane stack I1, wherein the tangential flow velocity of the dialysis liquid 5 is adjusted to 1.73cm / min, the tangential flow velocity ratio of the dialysis liquid 5 to the diffusion liquid is 1.2:1, the diffusion liquid and the dialysis liquid 5 are fed in in a cross-flow manner, and the outflow liquids are diffusion dialysis acid and diffusion residue 4, respectively. Correspondingly, a first liquid tank for receiving and recovering acid 3 (including diffusion dialysis acid) and a second liquid tank for receiving diffusion residue 4 are respectively set up, wherein the first liquid tank and the second liquid tank are both connected to the diffusion dialysis device. The diffusion dialysis acid solution obtained by diffusion dialysis is introduced into the concentrated and dilute chambers of the electrodialysis membrane stack I10 by peristaltic pump 6 at a volume ratio of 1:10. A 50% limiting current is applied to both sides of the electrodialysis membrane stack. When the conductivity of the dilute chamber (recovered acid solution 3) tends to stabilize or the pH changes drastically, the electrodialysis stops, and the concentrated solution obtained is the concentrated acid solution.

[0102] The acid recovered from the concentration chamber of electrodialysis membrane stack I10 can be used as a pectin extractant and recycled back to the lemon pomace pectin extraction process.

[0103] During or after electrodialysis acid concentration treatment via electrodialysis membrane stack I10, a diffusion residue 4, mainly composed of salt (ammonium nitrate), enters the concentration and dilute chambers of electrodialysis membrane stack II10a at a volume ratio of 1:10. The flow rate is adjusted to ensure that electrodialysis membrane stack II10a circulates at an appropriate flow rate. After electrodialysis membrane stack II10a has been running stably for a period of time, a limiting current of 50-70% is applied to both sides of electrodialysis membrane stack II10a. When the conductivity of the dilute chamber tends to stabilize or the pH changes drastically, the electrodialysis reaction stops, resulting in concentrated brine 9 and effluent after salt concentration treatment.

[0104] The concentrated brine 9 obtained by the electrodialysis membrane stack II 10a contains some acid. Therefore, diffusion dialysis membrane stack II is used to perform diffusion dialysis to recover the acid. The recovered secondary acid solution can be processed into the first liquid tank and used as the recovered acid solution 3 for electrodialysis acid concentration treatment. The further concentrated brine 12 obtained by diffusion dialysis membrane stack II can be used as high-quality liquid nitrogen fertilizer and can be directly applied to farmland.

[0105] The concentrated acid effluent obtained from the dilute chamber of electrodialysis membrane stack I10 can then enter reverse osmosis membrane stack I14. The inlet water temperature of reverse osmosis membrane stack I14 is adjusted to 25°C. After the air bubbles in the tube are eliminated and the flow meter reading tends to stabilize, the reverse osmosis operating pressure is adjusted to 30-60 Bar. Finally, reverse osmosis effluent I15 and reverse osmosis concentrated acid solution are obtained. The reverse osmosis concentrated acid solution can also be used as recycled acid solution 3 for electrodialysis acid concentration treatment to obtain the final concentrated acid solution.

[0106] The concentrated ammonium salt effluent obtained from the dilute chamber of electrodialysis membrane stack II10a can enter the reverse osmosis membrane stack II14a for reverse osmosis treatment to obtain reverse osmosis effluent II15a and reverse osmosis concentrated brine. The reverse osmosis ammonium salt solution can be used as part of the recovered brine to participate in the electrodialysis salt concentration treatment based on electrodialysis membrane stack II10a, while the reverse osmosis effluent II15a can be used as part of the dialysis solution 5 used in the diffusion dialysis treatment of diffusion dialysis membrane stack I1.

[0107] Using the method and system of this invention, the water quality test results of the treated acidic saline wastewater 2 are shown in Table 1 below.

[0108] Table 1. Water quality test results of treated wastewater

[0109]

[0110] The membrane material information applicable to this invention is shown in Table 2 below.

[0111] Table 2 Membrane Material Information

[0112]

[0113] The method and system of this invention are also applicable to other acidic saline wastewater, such as industrial wastewater from steel profile production. This type of industrial wastewater is formed by a mixture of hydrochloric acid and ferrous chloride, with a waste acid concentration of 5-8% and a ferrous salt concentration of 9-13%. The salt ions are ferrous salt ions. The concentrated acid solution obtained through the aforementioned method and system is a concentrated hydrochloric acid solution, and the concentrated salt solution is a concentrated ferrous salt solution. Specifically, after diffusion dialysis, electrodialysis, further diffusion dialysis of the concentrated salt solution for deacidification, and reverse osmosis treatment, the acid concentration (hydrochloric acid) is 20-25%, the ferrous salt concentration is 29-35%, the reverse osmosis effluent pH is 3-5, and the ferrous ion concentration is reduced to 5-10 mg / L.

[0114] The method and system of this invention are also applicable to copper electroplating industrial wastewater with a nitric acid-copper nitrate mixed system, wherein the waste acid concentration is 8-13% (nitric acid), the copper ion concentration is 30-40 g / L (copper nitrate), and the salt ion is copper ion. Using the method and system of this invention, the final treated acid concentration (nitric acid) can reach 25-32%, the copper ion concentration can reach 80-120 g / L, the reverse osmosis effluent pH is 3-5, and the copper ion concentration is reduced to 0.5-1 mg / L.

[0115] The method and system of this invention are also applicable to nickel plating industrial wastewater with a nitric acid-nickel ion mixed system, wherein the salt ions are nickel ions. Using the method and system of this invention, the final treated acid concentration (nitric acid) can reach 25-30%, the nickel ion concentration can reach 10-25 g / L, the reverse osmosis effluent pH is 3-5, and the nickel ion concentration will be less than 0.2-0.5 mg / L.

[0116] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0117] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0118] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0119] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for multi-resource recovery and treatment of acidic saline wastewater, characterized in that, The acidic, saline wastewater is pectin processing wastewater generated during pectin processing, and it exhibits a nitrate-ammonium nitrate mixed system, wherein the salt ions are ammonium ions; the method includes: Step S1: The acidic saline wastewater is subjected to diffusion dialysis treatment, so that hydrogen ions and acid radical ions enter the dialysis liquid to form diffusion dialysis acid solution, while salt ions are retained in the diffusion residue. Step S2: The recovered acid solution is subjected to electrodialysis acid concentration treatment to obtain concentrated acid solution and acid concentration treatment effluent, wherein the recovered acid solution includes the diffusion dialysis acid solution obtained according to step S1; and the recovered ammonium salt solution is subjected to electrodialysis salt concentration treatment to obtain concentrated ammonium salt solution and salt concentration treatment effluent, wherein the recovered ammonium salt solution includes the diffusion residue containing ammonium ions obtained according to step S1. Step S3: The concentrated acid solution obtained in step S2 based on electrodialysis concentrated acid treatment is used as a pectin extraction agent and back-input into the pectin extraction processing system for pectin extraction. After step S2 and before step S3, the following is also included: Step A1: The obtained acid concentration effluent is subjected to reverse osmosis treatment to obtain reverse osmosis effluent I and reverse osmosis concentrated acid solution. Step A2: The concentrated ammonium salt solution obtained in step S2 through electrodialysis salt concentration treatment is subjected to diffusion dialysis treatment again to perform re-deacidification, and a secondary recovered acid solution containing residual acid radical ions and a further concentrated ammonium salt solution are obtained. Step A3: The obtained reverse osmosis concentrated acid solution and secondary recycled acid solution are also included as part of the recycled acid solution and participate in the electrodialysis acid concentration treatment in step S2, so that the recycled acid solution used for electrodialysis acid concentration treatment in step S2 is composed of diffusion dialysis acid solution, reverse osmosis concentrated acid solution and secondary recycled acid solution. Step A4: The reverse osmosis effluent I obtained in step A1 is returned to the diffusion dialysis treatment of acidic saline wastewater in step S1 and used as part of the dialysis solution. Following step S2, which involves electrodialysis concentration of the recovered acid solution, the method further includes: Step B1: The obtained salt concentrate effluent is subjected to reverse osmosis treatment to obtain reverse osmosis effluent II and reverse osmosis concentrated ammonium salt solution. Step B2: The obtained reverse osmosis concentrated ammonium salt solution is used as part of the recovered ammonium salt solution and participates in the electrodialysis salt concentration treatment described in step S2. It also includes step B3, in which the obtained reverse osmosis effluent II is returned to the diffusion dialysis treatment of acidic saline wastewater in step S1, and used as part of the dialysis solution.

2. The method for multi-resource recovery and treatment of acidic saline wastewater according to claim 1, characterized in that, Before step S1, there is also step S0, which pretreatment the acidic saline wastewater, the pretreatment including at least filtering the acidic saline wastewater.

3. A system for implementing the multi-resource recovery and treatment method for acidic saline wastewater according to claim 1, characterized in that, include: Diffusion dialysis membrane stack I uses dialysis solution to treat acidic saline wastewater, which is a nitric acid-ammonium nitrate mixed system, by diffusion dialysis. Hydrogen ions and acid radical ions enter the dialysis solution to form diffusion dialysis acid solution, while salt ions are retained in the diffusion residue solution. Electrodialysis membrane stack I, which uses an acid concentration electrode solution to perform electrodialysis acid concentration treatment on the recovered acid solution to obtain concentrated acid solution and acid-concentrated effluent, wherein the recovered acid solution includes the diffusion dialysis acid solution obtained based on diffusion dialysis membrane stack I; Electrodialysis membrane stack II, which uses a salt concentration electrode solution to perform electrodialysis salt concentration treatment on the recovered ammonium salt solution to obtain concentrated ammonium salt solution and effluent after salt concentration treatment, wherein the recovered ammonium salt solution includes a diffusion residue containing ammonium ions obtained based on diffusion dialysis membrane stack I; Also includes: Reverse osmosis membrane stack I, which can perform reverse osmosis treatment on the acid concentrate effluent obtained based on electrodialysis membrane stack I to obtain reverse osmosis effluent I and reverse osmosis concentrated acid solution; Diffusion dialysis membrane stack II is capable of performing diffusion dialysis treatment on the concentrated ammonium salt solution obtained based on electrodialysis membrane stack II to perform re-deacidification and obtain a secondary recovered acid solution containing residual acid ions and a further concentrated ammonium salt solution. The recovered acid solution also includes the concentrated acid solution after reverse osmosis and the secondary recovered acid solution.

4. The system according to claim 3, characterized in that, The reverse osmosis effluent I obtained from the reverse osmosis membrane stack I can be used as part of the dialysis solution for diffusion dialysis treatment by the diffusion dialysis membrane stack I.

5. The system according to claim 3, characterized in that, It also includes reverse osmosis membrane stack II, which can perform reverse osmosis treatment on the effluent obtained after salt concentration treatment based on electrodialysis membrane stack II to obtain reverse osmosis effluent II and reverse osmosis concentrated ammonium salt solution. The reverse osmosis concentrated ammonium salt solution can be used as part of the recovered ammonium salt solution to participate in the electrodialysis salt concentration treatment based on electrodialysis membrane stack II.

6. The system according to claim 5, characterized in that, The reverse osmosis effluent II obtained from the reverse osmosis membrane stack II can be used as part of the dialysis solution for diffusion dialysis treatment by the diffusion dialysis membrane stack I.

7. The system according to any one of claims 3-6, characterized in that, It also includes a pretreatment device that can pretreat acidic saline wastewater before diffusion dialysis treatment based on diffusion dialysis membrane stack I; The pretreatment device includes at least a filter element for filtering acidic saline wastewater.

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