Ammonia-nitrogen wastewater treatment device capable of generating target ammonium salt and method thereof

Abstract

The invention discloses an ammonia-nitrogen wastewater treatment device and method capable of generating target ammonium salt, the ammonia-nitrogen wastewater treatment device comprises a bipolar membrane electrodialysis device and a membrane contactor, the bipolar membrane electrodialysis device comprises at least one treatment unit and an anode chamber and a cathode chamber which are separated by the treatment unit; the treatment unit comprises a front bipolar membrane, a front cation exchange membrane, a middle bipolar membrane, an anion exchange membrane, a rear cation exchange membrane and a rear bipolar membrane which are sequentially arranged in the direction from the anode chamber to the cathode chamber, and a feeding chamber, an ammonia production chamber, an acid production chamber, a desalting chamber and an alkali production chamber are respectively formed in spaces generated between the corresponding membranes; the membrane contactor comprises a breathable hydrophobic membrane dividing an inner cavity of the membrane contactor into a first chamber and a second chamber, and the first chamber and the second chamber communicate with the ammonia production chamber and the acid production chamber through pipelines correspondingly. And the method has relatively high application and popularization values.

Description

Technical Field

[0001] The present invention relates to the field of wastewater treatment technology and resource recovery, and in particular to an ammonia nitrogen wastewater treatment device and method capable of generating target ammonium salt. Background Art

[0002] High-concentration ammonia nitrogen wastewater discharged by my country's industry has become the main pollution source for the total amount of ammonia nitrogen discharge control. Its discharge is far higher than the capacity of the receiving water environment, becoming the main pollution source of surface water bodies and an important issue affecting my country's water ecology. High-concentration ammonia nitrogen wastewater has serious harm to the ecological environment and human body. First, the toxicity of non-ionized ammonia in ammonia nitrogen wastewater is dozens of times that of ammonium salts, which can easily produce strong toxic effects on aquatic organisms and human bodies; second, ammonia nitrogen is the main oxygen-consuming pollutant in water, which can easily consume dissolved oxygen in water and make the water body appear black and smelly; third, microorganisms will oxidize ammonia nitrogen into nitrite, which will combine with protein to form nitrosamines. This chemical substance has carcinogenic and teratogenic effects on organisms; fourth, the large-scale discharge of ammonia nitrogen wastewater will cause eutrophication of water bodies, promote the growth of algae in water bodies, and destroy the ecological balance of water bodies.

[0003] To this end, Chinese patent CN202111248560.5 discloses a scheme for treating ammonia nitrogen wastewater and recovering ammonia nitrogen resources in the wastewater, which mainly utilizes the acid ions and ammonium ions in the ammonia nitrogen wastewater to enter the respective acid-producing areas and ammonia-producing areas through the anion exchange membrane and cation exchange membrane respectively, and in the respective areas, they react with the hydrogen ions and hydroxide ions generated by electrolyzed water to form acid solution and ammonia solution respectively, and finally generate ammonium salt solution under the action of the membrane reactor to realize the recovery of ammonia nitrogen resources in the ammonia nitrogen wastewater. However, the scheme still has the following problems: 1) Anion exchange membranes and cation exchange membranes are set on both sides of the wastewater chamber. The cation exchange membrane will cause the ion concentration in the wastewater chamber to decrease after a period of operation, resulting in an increase in the operating voltage, increased energy consumption, and the anion membrane is more easily contaminated. 2) The acid formed comes from the acid radical ions in the waste liquid, which is extremely uncontrollable, resulting in poor purity of the final ammonium salt, and the type of acid cannot be selected, losing the advantage of directional output of the target ammonium salt. 3) The ammonium radical ions have to pass through two layers of cation exchange membranes to reach the target, and the migration process is complicated. Each step in the migration process may be accompanied by ammonia loss, affecting the final conversion efficiency of ammonia nitrogen resources. It will also affect the migration speed of ammonium radicals and reduce the efficiency of deammoniation. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide an ammonia nitrogen wastewater treatment device capable of generating target ammonium salts, which can effectively improve the conversion efficiency of ammonia nitrogen resources in ammonia nitrogen wastewater, and can produce high-purity target ammonium salts according to demand, which has high value, and can also reduce energy consumption and save costs.

[0005] The technical solutions adopted are as follows:

[0006] The invention discloses an ammonia nitrogen wastewater treatment device capable of generating target ammonium salt, comprising a bipolar membrane electrodialysis device and a membrane contactor, wherein the bipolar membrane electrodialysis device comprises at least one treatment unit and an anode chamber and a cathode chamber separated by the treatment unit; the treatment unit comprises:

[0007] A front bipolar membrane, a middle bipolar membrane and a rear bipolar membrane are arranged in sequence in a direction from the anode chamber to the cathode chamber;

[0008] A front cation exchange membrane is arranged between the first bipolar membrane and the middle bipolar membrane; wherein a feed chamber is formed between the front bipolar membrane and the front cation exchange membrane, and an ammonia production chamber is formed between the front cation exchange membrane and the middle bipolar membrane;

[0009] An anion exchange membrane and a post-position cation exchange membrane are sequentially arranged between the middle bipolar membrane and the post-position bipolar membrane in the direction from the anode chamber to the cathode chamber; wherein an acid-generating chamber is formed between the middle bipolar membrane and the anion exchange membrane, a desalting chamber is formed between the anion exchange membrane and the post-position cation exchange membrane, and an alkali-generating chamber is formed between the post-position cation exchange membrane and the post-position bipolar membrane;

[0010] Among them, the waste liquid to be treated enters from the feed chamber, and the ammonium ions in the waste liquid enter the ammonia production chamber through the front cation exchange membrane, and combine with the hydroxide ions produced by electrolyzing water in the ammonia production chamber through the middle bipolar membrane to generate ammonia water; the salt solution can be passed into the desalination chamber, and the acid ions in the salt solution enter the acid production chamber through the anion exchange membrane, and combine with the hydrogen ions produced by electrolyzing water in the acid production chamber through the middle bipolar membrane to generate acid; and the cations in the salt solution enter the alkali production chamber through the rear cation exchange membrane, and combine with the hydroxide ions produced by electrolyzing water in the alkali production chamber through the rear bipolar membrane to generate alkali;

[0011] The membrane contactor includes a breathable hydrophobic membrane, which divides the inner cavity of the membrane contactor into a relatively independent first chamber and a second chamber, wherein the first chamber is configured to be connected to the ammonia producing chamber to receive ammonia water generated by the ammonia producing chamber, and the second chamber is configured to be connected to the acid producing chamber to receive the acid generated by the acid producing chamber. The ammonia in the ammonia water can enter the second chamber through the breathable hydrophobic membrane, and then react with the acid received from the acid producing chamber in the second chamber to generate ammonium salt.

[0012] Since the present invention is provided with a relatively independent desalination chamber, when it is necessary to produce the target ammonium salt, it is only necessary to input the corresponding salt solution into the desalination chamber, and the acid radical ions contained in the salt solution in the desalination chamber enter the acid production chamber through the anion exchange membrane, and combine with the hydrogen ions produced by the electrolysis of water by the middle bipolar membrane in the acid production chamber to generate acid, and then enter the acid chamber through the second connecting pipe, while the ammonium radical ions in the ammonia nitrogen wastewater enter the ammonia production chamber through the front cation exchange membrane, and combine with the hydroxide ions produced by the electrolysis of water by the middle bipolar membrane in the ammonia production chamber to generate ammonia water, and then enter the alkali chamber through the first connecting pipe. The ammonia produced by the ammonia water in the alkali chamber enters the acid chamber through the breathable hydrophobic membrane and is captured by the acid in the acid chamber to generate the target ammonium salt. The cations contained in the salt solution in the desalination chamber enter the alkali production chamber through the post-cation exchange membrane and combine with the hydroxide ions produced by the post-bipolar membrane electrolysis of water in the alkali production chamber to generate alkali. Based on the above principle, different types of salt solutions are input into the desalination chamber regularly to achieve the synchronous output of the target ammonium salt and alkali, which not only ensures the purity of the final ammonium salt, but also greatly meets the customer's personalized customization needs, and has high application value.

[0013] At the same time, considering that most of the high-purity waste salt generated by industries such as petrochemicals and seawater desalination is still disposed of by discharging into the sea, the flexibility of the desalination chamber provided in the present invention is utilized to input the waste salt into the desalination chamber. Through the desalination process, valuable salts can be recovered from industrial waste salt, reducing resource waste, thereby improving the efficiency and sustainability of the entire industrial ecosystem.

[0014] When a single salt solution is input into the desalination chamber, the concentration of acid ions in the acid-producing chamber can be guaranteed, thereby ensuring that the final ammonium salt has a high purity and can also improve the output efficiency of the ammonium salt. However, the acid ions in the existing acid-producing chamber mostly come from ammonia nitrogen wastewater, which is highly uncontrollable and affects not only the purity of the final ammonium salt, but also the output efficiency of the ammonium salt.

[0015] The target ammonium salt of the present invention is related to the acid radical ions contained in the salt solution input into the desalination chamber. "Relatively independent" means that the desalination chamber is not affected by other chambers and can adapt to any salt solution input from the outside.

[0016] The present invention is based on the design of such a relatively independent desalination chamber, so that the salt solution used in it has high selectivity and high controllability, thereby converting the ammonia nitrogen resources in the ammonia nitrogen wastewater into the desired target ammonium salt, realizing the recovery of ammonia nitrogen resources in the wastewater, reducing the pollution to the environment, and conforming to the concept of circular economy. It can also produce the corresponding alkali, which has certain social promotion.

[0017] In the present invention, the two sides of the feed chamber are respectively provided with a front bipolar membrane and a front cation exchange membrane. Compared with the existing feed chamber in which the two sides are provided with an anion exchange membrane and a cation exchange membrane, the front bipolar membrane of the present invention will continuously generate hydrogen ions to the feed chamber, and the anions in the original waste liquid of the feed chamber do not migrate, thereby maintaining the ion concentration of the feed chamber. Therefore, it can effectively avoid the increase in operating voltage and energy consumption caused by the decrease in ion concentration in the feed chamber during operation, and more importantly, there will be no problem of anion exchange membrane being contaminated, thereby reducing the operating cost.

[0018] In the present invention, the ammonium ions in the ammonia nitrogen wastewater enter the ammonia production chamber only through the front cationic membrane to generate ammonia water, which greatly accelerates the migration speed, improves the deammoniation efficiency and the purity of the final ammonium salt product.

[0019] According to the ammonia nitrogen wastewater treatment device capable of generating target ammonium salt disclosed in the present invention, at least one treatment unit is provided, and they are arranged adjacent to each other in sequence in the direction from the anode chamber to the cathode chamber. In two adjacent treatment units, the rear bipolar membrane of the previous treatment unit serves as the front bipolar membrane of the latter treatment unit.

[0020] According to the ammonia nitrogen wastewater treatment device capable of generating target ammonium salt disclosed in the present invention, the salt solution is correspondingly set based on the type of target ammonium salt to be generated.

[0021] According to the ammonia nitrogen wastewater treatment device capable of generating target ammonium salt disclosed in the present invention, the target ammonium salt is ammonium nitrate, the salt solution is set as a nitrate salt solution, the acid generated by the acid generating chamber is nitric acid, and the base generated by the base generating chamber is a base corresponding to the cation in the salt solution.

[0022] According to the ammonia nitrogen wastewater treatment device capable of generating target ammonium salt disclosed in the present invention, the ammonia producing chamber is provided with a first connecting pipe for outputting ammonia water to the first chamber, the acid producing chamber is provided with a second connecting pipe for outputting acid liquid to the second chamber, the feed chamber is provided with a third connecting pipe for receiving external wastewater input, and pumps are provided on the first connecting pipe, the second connecting pipe and the third connecting pipe.

[0023] According to the ammonia nitrogen wastewater treatment device capable of generating target ammonium salt disclosed in the present invention, the pumps arranged on the first connecting pipe, the second connecting pipe and the third connecting pipe are peristaltic pumps.

[0024] According to the ammonia nitrogen wastewater treatment device capable of generating target ammonium salt disclosed in the present invention, the current density input to the ammonia nitrogen wastewater treatment device is 80A / ㎡ to 200A / ㎡.

[0025] According to the ammonia nitrogen wastewater treatment device capable of generating target ammonium salt disclosed by the present invention, the air-permeable hydrophobic membrane is a high-porosity air-permeable hydrophobic membrane. The air-permeable hydrophobic membrane has high selectivity for ammonia, and can transfer ammonia gas generated by the ammonia solution enriched in the first chamber to the second chamber in a timely manner, thereby improving the output efficiency of ammonium salt, and has high anti-pollution performance and long service life.

[0026] The present invention also discloses a method for treating an ammonia nitrogen wastewater capable of generating a target ammonium salt, which uses the ammonia nitrogen wastewater treatment device capable of generating a target ammonium salt disclosed above, and the method comprises the following steps:

[0027] The anode chamber and the cathode chamber are connected to the positive and negative electrodes of a power source respectively to generate a direct current electric field;

[0028] The ammonia nitrogen wastewater to be treated is transported to the feed chamber of the treatment unit, and the corresponding salt solution is selected according to the target ammonium salt and input into the desalination chamber, so that the ammonium ions contained in the ammonia nitrogen wastewater in the feed chamber enter the ammonia production chamber through the front cation exchange membrane under the action of the electric field, and combine with the hydroxide ions produced by the electrolysis of water by the middle bipolar membrane in the ammonia production chamber to generate an ammonia solution, and the acid ions contained in the desalination chamber enter the acid production chamber through the anion exchange membrane, and combine with the hydrogen ions produced by the electrolysis of water by the middle bipolar membrane in the acid production chamber to generate an acid solution, and the cations in the salt solution enter the alkali production chamber through the rear cation exchange membrane, and combine with the hydroxide ions produced by the electrolysis of water by the rear bipolar membrane in the alkali production chamber to generate alkali;

[0029] The ammonia solution generated by the ammonia production chamber and the acid solution generated by the acid production chamber are respectively input into the first chamber and the second chamber of the membrane contactor, so that the ammonia in the ammonia solution in the first chamber enters the second chamber through the gas-permeable hydrophobic membrane, and the acid solution in the second chamber captures the entering ammonia to enrich and form the target ammonium salt.

[0030] According to the method of the ammonia nitrogen wastewater treatment device capable of generating target ammonium salt disclosed in the present invention, the target ammonium salt is ammonium nitrate, the salt solution is set as a nitrate salt solution, and the acid generated in the acid generating chamber is nitric acid.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1) The type of salt solution used in the independent desalination chamber provided in the present invention is highly selective and controllable. On the one hand, the introduction of a single salt solution can ensure that the purity of the acid synthesized in the acid-producing chamber is high, thereby ensuring that the purity of the final ammonium salt is high and has a high utilization value; at the same time, by directional change of the type of salt solution in the desalination chamber, the type of the final ammonium salt and the type of alkali in the alkali-producing chamber can also be customized, meeting the customization and individualization needs of the product; on the other hand, the introduction of industrial waste salt can recover valuable salts from the industrial waste salt after the desalination process, reducing resource waste, converting it into usable chemical raw materials, improving the efficiency and sustainability of the entire industrial ecosystem, and complying with the concept of circular economy; and, the desalination chamber uses a high-conductivity electrolyte solution instead of water as an electrolyte. After the electrodialysis device is powered on, the resistance of the electrolyte solution is lower than that of water, thereby avoiding the increase in energy consumption of the entire device caused by the excessively high starting voltage of the system.

[0033] 2) The feed chamber of the present invention is provided with a front bipolar membrane and a front cation exchange membrane on both sides, respectively. Compared with the BMED system in which the feed chamber is provided with a cation exchange membrane and an anion exchange membrane on both sides, the risk of membrane contamination caused by electrostatic adsorption between negatively charged organic matter in the feed liquid and the positively charged groups on the anion exchange membrane is reduced, thereby ensuring efficient transmission of substances, improving the operating efficiency of the entire system, and reducing the cleaning frequency and maintenance cost of the device.

[0034] 3) The ammonium ions in the ammonia nitrogen wastewater of the present invention enter the ammonia production chamber only through the front cationic membrane to generate ammonia water, which greatly accelerates the migration speed, improves the deammoniation efficiency and the purity of the final ammonium salt product.

[0035] The ammonia nitrogen wastewater treatment device and method capable of generating target ammonium salt of the present invention are disclosed in detail below in conjunction with the embodiments shown in the accompanying drawings and the accompanying drawing numbers. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a simplified structural schematic diagram of the device of the present invention;

[0037] Figure 2 It is a schematic diagram of a physical model of the device of the present invention.

[0038] Reference numerals

[0039] 1 feeding chamber, 2 ammonia production chamber, 3 acid production chamber, 4 desalination chamber, 5 alkali production chamber, 6 anode chamber, 7 cathode chamber, 8 first chamber, 9 second chamber, 10 front bipolar membrane, 11 front cation exchange membrane, 12 middle bipolar membrane, 13 anion exchange membrane, 14 rear cation exchange membrane, 15 rear bipolar membrane, 16 breathable and hydrophobic membrane, 17 peristaltic pump, 18 processing unit, 19 first connecting pipeline, 20 second connecting pipeline, 21 third connecting pipeline. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other without conflict.

[0041] The technical solution provided by the present invention is used to treat high-concentration ammonia nitrogen wastewater. In the prior art, the following technical problems usually exist in the treatment of ammonia nitrogen wastewater: 1. Product purity: the anions in the feed liquid are usually not unique. If these anions are used to generate acid and then enriched in a membrane contactor, the purity of the ammonium salt obtained is not high and the value is very small; 2. The desalination chamber uses water as the electrolyte. Water with a larger resistance than the electrolyte will not only increase the starting voltage of the entire system, thereby increasing the energy consumption of the operation, but also the hydrogen ions have passed through the bipolar membrane to affect the rate and purity of acid and alkali production; 3. After the membrane-contaminated waste liquid enters the system, it contacts the anion exchange membrane and the cation exchange membrane. The anion exchange membrane with positively charged fixed groups is easy to electrostatically adsorb with the negatively charged organic matter in the wastewater, resulting in membrane surface contamination, which reduces its ion exchange capacity and increases the membrane resistance; 4. Insufficient resource utilization of high-purity industrial waste salt: the high-concentration saline wastewater generated by seawater desalination, petrochemical and other industries is directly discharged into the sea, causing ecological pollution, and the degree of resource utilization is not high.

[0042] In order to solve the above technical problems, the present invention provides an ammonia nitrogen wastewater treatment device and method capable of generating target ammonium salts, and specifically combines the drawings in the embodiments of the present invention to clearly and completely describe the technical scheme in the embodiments of the present invention.

[0043] like Figure 1 and Figure 2As shown, the ammonia nitrogen wastewater treatment device capable of generating target ammonium salt disclosed in the present invention comprises a bipolar membrane electrodialysis device and a membrane contactor, the bipolar membrane electrodialysis device comprises at least one treatment unit 18 and an anode chamber 6 and a cathode chamber 7 separated by the treatment unit, the treatment unit 18 comprises a front bipolar membrane 10, a front cation exchange membrane 11, a middle bipolar membrane 12, an anion exchange membrane 13, a rear cation exchange membrane 14 and a rear bipolar membrane 15 arranged in sequence from the anode chamber 6 to the cathode chamber 7, wherein the space generated between the front bipolar membrane 10 and the front cation exchange membrane 11 forms a feed chamber 1, the space generated between the front cation exchange membrane 11 and the middle bipolar membrane 12 forms an ammonia production chamber 2, the space generated between the middle bipolar membrane 12 and the anion exchange membrane 13 forms an acid production chamber 3, the space generated between the anion exchange membrane 13 and the rear cation exchange membrane 14 forms a desalination chamber 4, and the space generated between the rear cation exchange membrane 14 and the rear bipolar membrane 15 forms an alkali production chamber 5. In a particularly preferred embodiment, in a treatment unit 18, the front bipolar membrane 10, the front cation exchange membrane 11, the middle bipolar membrane 12, the anion exchange membrane 13, the rear cation exchange membrane 14 and the rear bipolar membrane 15 are all arranged as a layer to simplify the migration process and improve the deammoniation efficiency and the purity of the final product.

[0044] The membrane contactor includes a first chamber 8, a second chamber 9 and a breathable and hydrophobic membrane 16. The breathable and hydrophobic membrane 16 is arranged between the first chamber 8 and the second chamber 9 to separate the two. A first connecting pipe 19 is arranged between the first chamber 8 and the ammonia producing chamber 2, and the ammonia solution formed in the ammonia producing chamber 2 enters the first chamber 8 through the first connecting pipe 19. A second connecting pipe 20 is arranged between the second chamber 9 and the acid producing chamber 3, and the acid solution formed in the acid producing chamber 3 enters the second chamber 9 through the second connecting pipe 20.

[0045] In the implementation of the present invention, the feed chamber 1 is provided with a third connecting pipe 21 for receiving the input of high-concentration ammonia nitrogen wastewater from the outside. Preferably, the third connecting pipe 21 is provided with a peristaltic pump 17 .

[0046] In an embodiment of the present invention, the anode chamber 6 is connected to the positive electrode of the power supply, and the cathode chamber 7 is connected to the negative electrode of the power supply. Specifically, a metal plate can be set in the anode chamber 6 and the cathode chamber 7 respectively, which can be a titanium alloy or a nickel-based alloy. The metal plate of the anode chamber 6 is connected to the positive electrode of the power supply, and the metal plate of the cathode chamber 7 is connected to the negative electrode. After power is turned on, the entire device generates a DC electric field, and the front bipolar membrane 10, the middle bipolar membrane 12 and the rear bipolar membrane 15 work under the action of the DC electric field to decompose the water molecules in the middle layer into hydrogen ions and hydroxide ions.

[0047] In the present invention, the type of electrolyte solution used in the desalination chamber 4 is highly selective and controllable. When a single salt solution is introduced, it can ensure that the acid-generating chamber 3 synthesizes an acid with a high purity, thereby ensuring that a high-purity ammonium salt is finally obtained, which has a high application value; at the same time, by directional changes in the type of salt solution in the desalination chamber 4, the type of the final ammonium salt and the type of alkali produced by the alkali-generating chamber 5 can also be customized, meeting the customization and individualization needs of the product. In addition, the desalination chamber 4 uses a high-conductivity electrolyte solution instead of water as the electrolyte. After the bipolar membrane electrodialysis system is powered on, the resistance of the electrolyte solution is lower than that of water, which avoids the system's starting voltage being too high, resulting in an increase in the energy consumption of the entire device.

[0048] In the present invention, the two sides of the feed chamber 1 are respectively provided with a front bipolar membrane 10 and a front cation exchange membrane 11. Compared with the BMED system in which the two sides of the feed chamber are provided with a cation exchange membrane and an anion exchange membrane, the risk of membrane contamination caused by electrostatic adsorption between negatively charged organic matter in the feed chamber and the positively charged groups on the anion exchange membrane is reduced, the efficient transmission of substances can be ensured, the operating efficiency of the entire system is improved, and the cleaning frequency and maintenance cost of the device are reduced.

[0049] In the embodiment of the present invention, considering that most of the high-purity waste salts generated by industries such as petrochemicals and seawater desalination are still disposed of by discharging into the sea, the flexibility of the desalination chamber 4 designed in the present invention can be utilized to pass the industrial waste salt into the desalination chamber 4. Through the desalination process, valuable salts can be recovered from the industrial waste salts, reducing resource waste and converting them into usable chemical raw materials, thereby improving the efficiency and sustainability of the entire industrial ecosystem.

[0050] The treatment unit 18 of the present invention realizes the selection of the types of acid, alkali and salt produced by the system, and the repetitive structure of the treatment units 18 formed by sequential connection makes it have the characteristics of high efficiency, low energy consumption and high selectivity, which greatly improves the resource efficiency of ammonia nitrogen wastewater, converts ammonia nitrogen resources into useful chemicals, reduces pollution to the environment, and conforms to the concept of circular economy. Other configurations using simple chambers cannot select the type of acid produced by the system; or require additional chemical additives, which consumes high energy; or are set up as cation exchange membranes and anion exchange membranes on both sides of the feed chamber, which is more likely to cause membrane pollution; or directly pass into the membrane contactor after adjusting the pH in the feed chamber, and impurity ions are likely to cause pollution of the air-permeable and hydrophobic membrane.

[0051] In the present invention, when there is one processing unit 18, the front bipolar membrane 10 is separated from the anode chamber 6, and the rear bipolar membrane 15 is separated from the cathode chamber 7. When there are two or more processing units 18, between the processing units 18, the front bipolar membrane 10 of the processing unit 18 closest to the anode chamber 6 is separated from the anode chamber 6, and the rear bipolar membrane 15 of the processing unit 18 closest to the cathode chamber 7 is separated from the cathode chamber 7.

[0052] like Figure 1 As shown, in a preferred embodiment, at least one treatment unit 18 is provided, and they are arranged adjacently in sequence in the direction from the anode chamber 6 to the cathode chamber 7. In two adjacent treatment units 18, the rear bipolar membrane 15 of the previous treatment unit 18 serves as the front bipolar membrane 10 of the next treatment unit 18. In this embodiment, the hydroxide ions generated on one side of the rear bipolar membrane 15 of the previous treatment unit 18 are used to combine with the cations in the desalination chamber 4 to generate a base, and the hydrogen ions generated on one side of the front bipolar membrane 10 of the next treatment unit 18 are used to maintain the solution concentration in the feed chamber 1 after the migration of the ammonium ions.

[0053] In a preferred embodiment, the salt solution is set accordingly based on the type of target ammonium salt to be generated. In a specific embodiment of the present invention, the target ammonium salt is ammonium nitrate, and the salt solution is set as a nitrate salt solution, then the acid generated by the acid generating chamber 3 is nitric acid, and the base generated by the base generating chamber 3 is a base corresponding to the cation in the salt solution.

[0054] like Figure 1 As shown, in this embodiment of the present invention, the ammonia producing chamber 2 is provided with a first connecting pipe 19 for outputting ammonia water to the first chamber 8, the acid producing chamber 3 is provided with a second connecting pipe 20 for outputting acid liquid to the second chamber 9, and the feed chamber 1 is provided with a third connecting pipe 21 for receiving external wastewater input, and pumps are provided on the first connecting pipe 19, the second connecting pipe 20 and the third connecting pipe 21.

[0055] like Figure 1 and Figure 2 As shown, in a preferred embodiment, the pumps provided on the first connecting pipe 19, the second connecting pipe 20 and the third connecting pipe 21 are peristaltic pumps 17. In this embodiment, the chamber of the bipolar membrane electrodialysis system is connected to the membrane contactor through the peristaltic pump 17, and the NH4 in the feed liquid + The OH produced by electrolysis of water by the middle bipolar membrane 12 enters the ammonia production chamber 2 through the front cation exchange membrane 11. -1The NH3·H2O is combined to form NH3·H2O, which is then transferred to the first chamber 8 of the membrane contactor. Ammonia enters the second chamber 9 through the air-permeable hydrophobic membrane 16. The solution in the acid-generating chamber 3 enters the second chamber 9 of the membrane contactor to capture the diffused ammonia and achieve ammonia enrichment. Such continuous operation simplifies the operation process of the system and facilitates the realization of automatic control. It also prevents the overflow of ammonia, ensures the deammoniation efficiency of the system, and prevents the concentration of ammonia in the ammonia-generating chamber from being too high, resulting in reverse diffusion of ammonia.

[0056] In the embodiment of the present invention, the current density input to the ammonia nitrogen wastewater treatment device is 80A / ㎡~200A / ㎡.

[0057] In a preferred embodiment, the air-permeable hydrophobic membrane 16 is a high-porosity air-permeable hydrophobic membrane. It has high selectivity for ammonia, can transfer ammonia gas generated by the ammonia solution enriched in the first chamber 8 to the second chamber 9 in a timely manner, thereby improving the output efficiency of ammonium salt, and has high anti-pollution performance and long service life.

[0058] In the ammonia nitrogen wastewater treatment device of the present invention, the working process is as follows: after the system is powered on, the front bipolar membrane (BPM) 10, the middle bipolar membrane (BPM) 12 and the rear bipolar membrane (BPM) 15 electrolyze water to generate OH on the side close to the anode chamber 6. -1 , H is generated on the cathode side 7 + At the same time, NH4 in the wastewater + The generated OH is exchanged through the front cation exchange membrane (CEM) 11 -1 The combined NH3·H2O is transferred to the membrane contactor by the peristaltic pump 17 to achieve wastewater deammoniation. The corresponding electrolyte solution (NaNO3) is selectively added to the desalination chamber 4 according to the type of target ammonia salt (taking NH4NO3 as an example), and NO3 -1 The generated H + The combined HNO3 is transferred to the membrane contactor through a peristaltic pump 17 to strip the NH3·H2O and Na + The OH generated by the rear cation exchange membrane (AEM) 14 and the rear bipolar membrane (BPM) 15 at the other end -1 Combined with the generation of NaOH, the simultaneous generation of acid and alkali is achieved; Membrane contactor (MC): The two chambers of the membrane contactor are separated by a gas-permeable hydrophobic membrane 16, one side receives NH3·H2O transferred from the ammonia production chamber 2, and the other side receives HNO3 transferred from the acid production chamber 3. Due to the volatility of ammonia, the transmembrane transport difference trend of ammonia vapor pressure allows ammonia to be transported from one side to the HNO3 side through the gas-permeable hydrophobic membrane 16, thereby being further enriched to generate NH4NO3, while other non-volatile substances cannot pass through the membrane, thus realizing the resource recovery process of ammonia in wastewater.

[0059] The present invention also discloses a method for treating an ammonia nitrogen wastewater device capable of generating a target ammonium salt, which uses the ammonia nitrogen wastewater treatment device capable of generating a target ammonium salt disclosed in the above embodiment, and the method comprises the following steps:

[0060] The anode chamber 6 and the cathode chamber 7 are respectively connected to the positive and negative electrodes of a power source to generate a DC electric field;

[0061] The ammonia nitrogen wastewater to be treated is transported to the feed chamber 1 of the treatment unit, and the corresponding salt solution is selected according to the target ammonium salt and input into the desalination chamber 4, so that the ammonium ions contained in the ammonia nitrogen wastewater in the feed chamber 1 enter the ammonia production chamber 2 through the front cation exchange membrane 11 under the action of the electric field, and combine with the hydroxide ions produced by the electrolysis of water by the middle bipolar membrane 12 in the ammonia production chamber 2 to generate an ammonia solution, and the acid ions contained in the desalination chamber 4 enter the acid production chamber 3 through the anion exchange membrane 13, and combine with the hydrogen ions produced by the electrolysis of water by the middle bipolar membrane 12 in the acid production chamber 3 to generate an acid solution, and the cations in the salt solution enter the alkali production chamber 5 through the rear cation exchange membrane 14, and combine with the hydroxide ions produced by the electrolysis of water by the rear bipolar membrane 15 in the alkali production chamber 5 to generate alkali;

[0062] The ammonia solution generated by the ammonia production chamber 2 and the acid solution generated by the acid production chamber 3 are respectively input into the first chamber 8 and the second chamber 9 of the membrane contactor, so that the ammonia in the ammonia solution in the first chamber 8 enters the second chamber 9 through the air-permeable and hydrophobic membrane 16, and the acid solution in the second chamber 9 captures the entering ammonia to enrich and form the target ammonium salt.

[0063] like Figure 2 As shown, in one embodiment, the target ammonium salt is ammonium nitrate, the salt solution is set to be a nitrate salt solution, and the acid generated by the acid generating chamber is nitric acid.

[0064] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. An ammonia nitrogen wastewater treatment device capable of generating target ammonium salt, characterized in that: It includes a bipolar membrane electrodialysis device and a membrane contactor, The bipolar membrane electrodialysis device comprises at least one processing unit (18) and an anode chamber (6) and a cathode chamber (7) separated by the processing unit (18); the processing unit (18) comprises: A front bipolar membrane (10), a middle bipolar membrane (12) and a rear bipolar membrane (15), which are arranged in sequence in a direction from the anode chamber (6) to the cathode chamber (7); A front cation exchange membrane (11) is arranged between the first bipolar membrane (10) and the middle bipolar membrane (12); wherein a feed chamber (1) is formed between the front bipolar membrane (10) and the front cation exchange membrane (11), and an ammonia production chamber (2) is formed between the front cation exchange membrane (11) and the middle bipolar membrane (12); An anion exchange membrane (13) and a post-position cation exchange membrane (14) are sequentially arranged between the middle bipolar membrane (12) and the post-position bipolar membrane (15) in the direction from the anode chamber (6) to the cathode chamber (7); wherein an acid production chamber (3) is formed between the middle bipolar membrane (12) and the anion exchange membrane (13), a desalination chamber (4) is formed between the anion exchange membrane (13) and the post-position cation exchange membrane (14), and an alkali production chamber (5) is formed between the post-position cation exchange membrane (14) and the post-position bipolar membrane (15); The waste liquid to be treated enters from the feed chamber (1), and the ammonium ions in the waste liquid enter the ammonia production chamber (2) through the front cation exchange membrane (11), and combine with the hydroxide ions produced by electrolyzing water in the ammonia production chamber (2) through the middle bipolar membrane (12) to generate ammonia water; the salt solution can be passed into the desalination chamber (4), and the acid ions in the salt solution enter the acid production chamber (3) through the anion exchange membrane (13), and combine with the hydrogen ions produced by electrolyzing water in the acid production chamber (3) through the middle bipolar membrane (12) to generate acid; and the cations in the salt solution enter the alkali production chamber (5) through the rear cation exchange membrane (14), and combine with the hydroxide ions produced by electrolyzing water in the alkali production chamber (5) through the rear bipolar membrane (15) to generate alkali; The membrane contactor comprises an air-permeable and hydrophobic membrane (16), wherein the air-permeable and hydrophobic membrane (16) separates the inner cavity of the membrane contactor into a relatively independent first chamber (8) and a second chamber (9), wherein the first chamber (8) is configured to be connected to the ammonia producing chamber (2) to receive the ammonia water generated by the ammonia producing chamber (2), and the second chamber (9) is configured to be connected to the acid producing chamber (3) to receive the acid generated by the acid producing chamber (3), and the ammonia in the ammonia water can enter the second chamber (9) through the air-permeable and hydrophobic membrane (16), and then react with the acid received from the acid producing chamber (3) in the second chamber (9) to generate an ammonium salt.

2. The ammonia nitrogen wastewater treatment device capable of generating target ammonium salt according to claim 1, characterized in that: At least one processing unit (18) is provided and arranged adjacently in sequence in the direction from the anode chamber (6) to the cathode chamber (7); in two adjacent processing units (18), the rear bipolar membrane (15) of the previous processing unit (18) serves as the front bipolar membrane (10) of the next processing unit (18).

3. The ammonia nitrogen wastewater treatment device capable of generating target ammonium salt according to claim 1, characterized in that: The salt solution is set accordingly based on the type of target ammonium salt to be generated.

4. The ammonia nitrogen wastewater treatment device capable of generating target ammonium salt according to claim 3, characterized in that: The target ammonium salt is ammonium nitrate, and the salt solution is set to be a nitrate salt solution. The acid generated by the acid generating chamber (3) is nitric acid, and the base generated by the base generating chamber (3) is a base corresponding to the cation in the salt solution.

5. The ammonia nitrogen wastewater treatment device capable of generating target ammonium salt according to claim 1, characterized in that: The ammonia production chamber (2) is provided with a first connecting pipe (19) for outputting ammonia water to the first chamber (8), the acid production chamber (3) is provided with a second connecting pipe (20) for outputting acid liquid to the second chamber (9), and the feed chamber (1) is provided with a third connecting pipe (21) for receiving external wastewater input, and the first connecting pipe (19), the second connecting pipe (20) and the third connecting pipe (21) are all provided with pumps.

6. The electrochemical device for recovering ammonia nitrogen resources in high-concentration ammonia nitrogen wastewater and converting it into target ammonium salt according to claim 5, characterized in that: The pumps provided on the first connecting pipe (19), the second connecting pipe (20) and the third connecting pipe (21) are peristaltic pumps (17).

7. The ammonia nitrogen wastewater treatment device capable of generating target ammonium salt according to claim 1, characterized in that: The current density input to the ammonia nitrogen wastewater treatment device is 80A / ㎡~200A / ㎡.

8. The ammonia nitrogen wastewater treatment device capable of generating target ammonium salt according to any one of claims 1 to 7, characterized in that: The air-permeable and hydrophobic membrane (16) is an air-permeable and hydrophobic membrane with high porosity.

9. A method for an ammonia nitrogen wastewater treatment device capable of generating a target ammonium salt, characterized in that: The method uses an ammonia nitrogen wastewater treatment device capable of generating a target ammonium salt according to any one of claims 1 to 8, and the method comprises the following steps: The anode chamber (6) and the cathode chamber (7) are respectively connected to the positive and negative electrodes of a power source to generate a direct current electric field; The ammonia nitrogen wastewater to be treated is transported to the feed chamber (1) of the treatment unit, and the corresponding salt solution is selected according to the target ammonium salt and input into the desalting chamber (4), so that the ammonium ions contained in the ammonia nitrogen wastewater in the feed chamber (1) enter the ammonia producing chamber (2) through the front cation exchange membrane (11) under the action of the electric field, and combine with the hydroxide ions generated by the electrolysis of water by the middle bipolar membrane (12) in the ammonia producing chamber (2) to generate an ammonia solution, while the acid ions contained in the desalting chamber (4) enter the acid producing chamber (3) through the anion exchange membrane (13), and combine with the hydrogen ions generated by the electrolysis of water by the middle bipolar membrane (12) in the acid producing chamber (3) to generate an acid solution, and the cations in the salt solution enter the alkali producing chamber (5) through the rear cation exchange membrane (14), and combine with the hydroxide ions generated by the electrolysis of water by the rear bipolar membrane (15) in the alkali producing chamber (5) to generate an alkali; The ammonia aqueous solution generated by the ammonia producing chamber (2) and the acid solution generated by the acid producing chamber (3) are respectively input into the first chamber (8) and the second chamber (9) of the membrane contactor, so that the ammonia in the ammonia aqueous solution in the first chamber (8) enters the second chamber (9) through the gas-permeable hydrophobic membrane (16), and the acid solution in the second chamber (9) captures the entering ammonia to enrich and form the target ammonium salt.

10. The method according to claim 9, characterized in that The target ammonium salt is ammonium nitrate, and the salt solution is set to be a nitrate salt solution, and the acid generated in the acid generating chamber is nitric acid.

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