Apparatus capable of simultaneously separating and recovering ammonia and phosphoric acid using bipolar membrane electrodialysis device

Abstract

The present invention relates to an apparatus capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device, wherein the apparatus can simultaneously separate and recover, with high efficiency, ammonia and phosphoric acid present in high-concentration organic wastewater. The apparatus capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device, according to the present invention, comprises: a wastewater pre-processing tank that lowers the pH of wastewater; a wastewater supply tank that receives pre-processed wastewater from the wastewater pre-processing tank and supplies the pre-processed wastewater to the bipolar membrane electrodialysis device; the bipolar membrane electrodialysis device which simultaneously separates the ammonia and phosphoric acid contained in the wastewater; an ammonia concentrate tank that receives an ammonia concentrate from a base region (B) of the bipolar membrane electrodialysis device and stores the ammonia concentrate, wherein the ammonia concentrate is generated in the base region (B); and a phosphoric acid concentrate tank that receives a phosphoric acid concentrate from an acid region (A) of the bipolar membrane electrodialysis device and stores the phosphoric acid concentrate, wherein the phosphoric acid concentrate is generated in the acid region (A).

Description

A device capable of simultaneous separation and recovery of ammonia and phosphoric acid using a bipolar membrane electrodialysis device

[0001] The present invention was made under the support of the Rural Development Administration of the Republic of Korea under the project identification number 1545027351, and the research management specialized institution of the project is the National Institute of Agricultural Sciences and Technology Planning and Evaluation, the research project name is “Smart Farm Multi-Ministry Package Innovation Technology Development”, the research project name is “Nitrogen Reduction by Electrodialysis of Anaerobic Digestion”, and the research period is 2023.01.01-2023.12.31.

[0002] The present invention relates to a device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device, and more specifically, to a device capable of simultaneously separating and recovering ammonia and phosphoric acid present in high-concentration organic wastewater with excellent efficiency using a bipolar membrane electrodialysis device.

[0003] Existing technologies for recovering nitrogen and phosphorus from high-concentration wastewater include precipitation in the form of a salt formed by combining ammonia and phosphoric acid, such as struvite, or absorption methods using ammonia stripping methods or ion exchange resins. However, struvite is a salt formed by combining ammonia and phosphoric acid, so its uses are limited except for fertilizer, and it has the disadvantage of requiring the addition of additional chemicals such as magnesium for precipitation. In addition, ammonia stripping also has the disadvantage of requiring the use of acid and alkaline chemicals to adjust the pH and the injection of a large amount of air. In addition, there are many disadvantages in the case of absorption and recovery using ion exchange resins, such as the use of chemicals for desorption.

[0004] Meanwhile, the electrodialysis process is being applied in various fields. Electrodialysis is a process that uses electrical energy to selectively pass ions through an ion exchange membrane within an electric field, thereby separating ionic substances for desalination, purification, concentration, and recovery. Representative applications of electrodialysis include seawater desalination, wastewater treatment, removal of heavy metals from soil, and separation and purification of organic acids.

[0005] As a technology that applies electrodialysis to wastewater treatment, Korean Patent Publication No. 2023-0134972 (Patent Document 1), Japanese Patent Publication No. 2022-97062 (Patent Document 2), and Non-Patent Document 1 (Recovery of ammonia from simulated membrane contactor effluent using bipolar membrane electrodialysis D Saabas, J Lee - Journal of Membrane Science, 2022) can be examined.

[0006] Patent document 1 relates to a technology for recovering ammonia contained in wastewater using an isothermal membrane evaporator and a three-compartment bipolar membrane electrodialysis device, wherein ammonia (NH3) in wastewater is converted into ammonium sulfate ((NH4)2SO4) using an isothermal membrane evaporator, and ammonium sulfate ((NH4)2SO4) is converted into sulfate ion (SO4) through a bipolar membrane electrodialysis device. 2- ) and ammonium ion (NH 4+ ) and then converting them into sulfuric acid (H2SO4) and ammonia (NH3), respectively.

[0007] In the case of patent document 2, it is characterized by separating and recovering HF and NH4OH from industrial wastewater containing HF and NH4F using a two-compartment electrodialysis device, and F in the wastewater - is moved to the acid chamber (137), and NH4 in the alkali chamber (138) + and OH - reacts to form NH4OH.

[0008] Non-patent document 1 relates to an ammonia recovery technology using a membrane contactor (MC) and a two-compartment electrodialysis device, characterized in that ammonium phosphate salt is generated in the MC, the generated ammonium phosphate salt is supplied to a two-compartment electrodialysis device, and ammonia is separated through the two-compartment electrodialysis device. The process efficiency was analyzed according to the ammonia concentration, pH, and acid-base ratio of the raw water, and it is reported that approximately 68% of ammonia recovery is possible. However, both patent documents 1, 2, and non-patent document 1 have a disadvantage in that they can only separate and recover ammonium ions in wastewater, and cannot simultaneously separate nitrogen and phosphorus, which generally coexist in wastewater, that is, ammonia nitrogen and phosphate.

[0009] [Prior Art Literature]

[0010] [Patent Document]

[0011] (Patent Document 1) Korean Patent Publication No. 2023-0134972 (Published on September 22, 2023)

[0012] (Patent Document 2) Japanese Patent Application Laid-Open No. 2022-97062 (Published on June 30, 2022)

[0013] (Patent Document 3) U.S. Patent Publication No. US 2021-0229040 (published on July 29, 2021)

[0014] [Non-patent literature]

[0015] (Non-patent Document 1) Recovery of ammonia from simulated membrane contactor effluent using bipolar membrane electrodialysis D Saabas, J Lee - Journal of Membrane Science, 2022

[0016] The present invention has been devised to solve the above problems, and its purpose is to provide a device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device capable of simultaneously separating and recovering ammonia and phosphoric acid present in high-concentration organic wastewater with excellent efficiency.

[0017] In order to achieve the above object, a device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device according to the present invention comprises: a wastewater pretreatment tank for lowering the pH of wastewater; a wastewater supply tank for receiving wastewater pretreated in the wastewater pretreatment tank and supplying it to a bipolar membrane electrodialysis device; a bipolar membrane electrodialysis device for simultaneously separating ammonia and phosphoric acid contained in wastewater; an ammonia concentration tank for receiving and storing an ammonia concentrate generated in a base region (B) of the bipolar membrane electrodialysis device from a base region (B) and storing it; and a phosphoric acid concentration tank for receiving and storing a phosphoric acid concentrate generated in an acid region (A) of the bipolar membrane electrodialysis device from an acid region (A).

[0018] The above bipolar membrane electrodialysis device has a reaction tank, and an anode (+) and a cathode (-) are respectively provided at both ends of the reaction tank, and a bipolar membrane (BM), an anion exchange membrane (AEM), and a cation exchange membrane (CEM) are sequentially spaced between the anode (+) and the cathode (-), so that the space between the bipolar membrane (BM) and the anion exchange membrane (AEM) is defined as an acid region (A), the space between the anion exchange membrane (AEM) and the cation exchange membrane (CEM) is defined as a salt region (S), and the space between the cation exchange membrane (CEM) and the bipolar membrane (BM) is defined as a base region (B), and wastewater from the wastewater supply tank is supplied to the salt region (S).

[0019] Hydrogen ions (H) generated by water decomposition in the bipolar membrane (BM) + ), hydroxide ion (OH - ) are moved to the acid region (A) and the base region (B), respectively, and ammonium ions (NH4) contained in the wastewater supplied to the salt region (S) +) passes through the cation exchange membrane (CEM) and moves to the base zone (B), and the phosphate ion (PO3) contained in the wastewater supplied to the salt zone (S) 4- ) passes through the anion exchange membrane (AEM) and moves to the acid region (A), and ammonium ions (NH4) move to the base region (B). + ) is a hydroxide ion (OH - ) reacts with ammonia (NH3) and is converted into phosphate ion (PO3) that moves to the acid region (A). 4- ) is a hydrogen ion (H + ) reacts with hydrogen phosphate ion (HPO4) 2- ), dihydrogen phosphate ion (H2PO4 - ), phosphoric acid (H3PO4).

[0020] The ammonia concentrate produced in the base area (B) is moved to the ammonia concentrate tank, and the phosphoric acid concentrate produced in the acid area (A) is moved to the phosphoric acid concentrate tank.

[0021] The phosphoric acid concentrate from the phosphoric acid concentration tank is supplied to the wastewater pretreatment tank, where the pH of the wastewater is adjusted to 4 to 6. As the pH of the wastewater is adjusted to 4 to 6 in the wastewater pretreatment tank, carbonate ions in the wastewater are removed, the ammonium ion / ammonia ratio in the wastewater increases, and non-reactive phosphorus in the wastewater is converted into the form of orthophosphate ions.

[0022] The above bipolar membrane electrodialysis device has a reaction tank, and an anode (+) and a cathode (-) are respectively provided at both ends of the reaction tank, and a bipolar membrane (BM) and an anion exchange membrane (AEM) are alternately and repeatedly arranged between the anode (+) and the cathode (-), and the space between the bipolar membrane (BM) and the anion exchange membrane (AEM) is defined as an acid region (A), and the space between the anion exchange membrane (AEM) and the bipolar membrane (BM) is defined as a base region (B), and wastewater from a wastewater supply tank can be supplied to the base region (B).

[0023] Hydrogen ions (H) generated by water decomposition in the bipolar membrane (BM) + ), hydroxide ion (OH -) are moved to the acid region (A) and the base region (B), respectively, and the phosphate ion (PO3) contained in the wastewater supplied to the base region (B) 4- ) passes through the anion exchange membrane (AEM) and moves to the acid zone (A), and ammonium ions (NH4) of the wastewater supplied to the base zone (B) + ) is located in the base region (B), and the ammonium ion (NH4) present in the base region (B) + ) is a hydroxide ion (OH - ) reacts with ammonia (NH3) and is converted into phosphate ion (PO3) that moves to the acid region (A). 4- ) is a hydrogen ion (H + ) reacts with hydrogen phosphate ion (HPO4) 2- ), dihydrogen phosphate ion (H2PO4 - ), phosphoric acid (H3PO4), and the ammonia concentrate produced in the base region (B) is moved to the ammonia concentration tank, and the phosphoric acid concentrate produced in the acid region (A) is moved to the phosphoric acid concentration tank.

[0024] In addition, the bipolar membrane electrodialysis device has a reaction tank, and an anode (+) and a cathode (-) are respectively provided at both ends of the reaction tank, and a bipolar membrane (BM) and a cation exchange membrane (CEM) are alternately and repeatedly arranged between the anode (+) and the cathode (-), and the space between the bipolar membrane (BM) and the cation exchange membrane (CEM) is defined as an acid region (A), and the space between the cation exchange membrane (CEM) and the bipolar membrane (BM) is defined as a base region (B), and wastewater from the wastewater supply tank can be supplied to the acid region (A).

[0025] Hydrogen ions (H) generated by water decomposition in the bipolar membrane (BM) + ), hydroxide ion (OH - ) are moved to the acid region (A) and the base region (B), respectively, and the ammonium ion (NH4) contained in the wastewater supplied to the acid region (A) + ) passes through the cation exchange membrane (CEM) and moves to the base zone (B), and the phosphate ion (PO3) contained in the wastewater supplied to the acid zone (A) 4-) is located in the acid region (A) and the ammonium ion (NH4) moves to the base region (B). + ) is a hydroxide ion (OH - ) reacts with ammonia (NH3) and is converted into phosphate ion (PO3) present in the acid region (A). 4- ) is a hydrogen ion (H + ) reacts with hydrogen phosphate ion (HPO4) 2- ), dihydrogen phosphate ion (H2PO4 - ), phosphoric acid (H3PO4), and the ammonia concentrate produced in the base region (B) is moved to the ammonia concentration tank, and the phosphoric acid concentrate produced in the acid region (A) is moved to the phosphoric acid concentration tank.

[0026] The phosphoric acid concentrate from the phosphoric acid concentration tank is transferred to the phosphoric acid recovery device, which produces calcium orthophosphate through the reaction between the phosphoric acid concentrate and calcium salt.

[0027] The ammonia concentrate from the ammonia concentration tank is transferred to the ammonia recovery device, and the ammonia recovery device recovers ammonia from the ammonia concentrate using an ammonia stripper or a gas separation membrane that induces separation and permeation of ammonia.

[0028] A device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device according to the present invention has the following effects.

[0029] Ammonia and phosphoric acid can be separated simultaneously through a bipolar membrane electrodialysis device, and the separation efficiency of ammonium ions and phosphate ions can be improved by lowering the pH of the wastewater through wastewater pretreatment to remove carbonate ions in the wastewater, increasing the ammonium ion / ammonia ratio, and converting non-reactive phosphorus into the form of orthophosphate ions.

[0030] Figure 1 is a configuration diagram of a device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device according to one embodiment of the present invention.

[0031] Figure 2 is a configuration diagram of a bipolar membrane electrodialysis device according to one embodiment of the present invention.

[0032] Figure 3 is a configuration diagram of a bipolar membrane electrodialysis device according to a first modified embodiment of the present invention.

[0033] Figure 4 is a configuration diagram of a bipolar membrane electrodialysis device according to a second modified embodiment of the present invention.

[0034] Figures 5a and 5b are experimental results showing the removal and recovery efficiency of ammonia and phosphoric acid in synthetic wastewater according to Experimental Example 1.

[0035] Figure 6 is an experimental result showing the removal and recovery efficiency of ammonia in livestock manure digestate according to Experimental Example 2.

[0036] Figure 7 is an experimental result showing the ammonia removal efficiency depending on whether wastewater pretreatment was performed according to Experimental Example 3.

[0037] The present invention proposes a technology capable of simultaneously separating and recovering ammonia and phosphoric acid present in high-concentration organic wastewater, such as livestock manure digestate, using a bipolar membrane electrodialysis device. Furthermore, the present invention proposes a technology capable of improving the separation and recovery efficiency of ammonium ions and phosphate ions through wastewater pretreatment.

[0038] Hereinafter, a device capable of simultaneous separation and recovery of ammonia and phosphoric acid using a bipolar membrane electrodialysis device according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0039] Referring to FIG. 1, a device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device according to one embodiment of the present invention comprises a wastewater pretreatment tank (110), a wastewater supply tank (120), a bipolar membrane electrodialysis device (130), an ammonia concentration tank (140), and a phosphoric acid concentration tank (150).

[0040] The wastewater pretreatment tank (110) lowers the pH of the wastewater using an acid solution, and by lowering the pH of the wastewater, dissolved carbonates present in the wastewater are removed, thereby increasing the electrical conductivity of the bipolar membrane electrodialysis device (130) when separating ammonium ions in the bipolar membrane electrodialysis device (130), thereby increasing the separation speed of the ions. Carbonates have the characteristic of lower electrical conductivity than other salts, and when carbonates are present in the wastewater, they act as a factor lowering the overall electrical conductivity of the bipolar membrane electrodialysis device. Therefore, when dissolved carbonates present in the wastewater are removed by adjusting the pH of the wastewater, the movement speed of ions including ammonium ions increases, thereby improving the separation speed of the ammonium ions.

[0041] At this time, it is desirable that the pH of the wastewater in the wastewater pretreatment tank (110) be adjusted to 4 to 6. Carbonate is produced at a pH of about 4.5 to 8.3 by forming bicarbonate ions (HCO3 - ) and exhibits the characteristic of being converted to carbonic acid (H2CO3) at a pH of about 4.5 or lower, so carbonate can be effectively removed by adjusting the pH of the wastewater pretreatment tank (110) to 4 to 6.

[0042] In addition, as the pH of the wastewater is lowered to 4 to 6 in the wastewater pretreatment tank (110), free ammonia (NH3) is converted to ammonium ion (NH4). + ) is converted into ammonium ion / ammonia ratio, thereby increasing the ammonium ion separation efficiency of wastewater. As is known, free ammonia (NH3) is converted into ammonium ion (NH4) at pH below about 9.3. + ) is converted to .

[0043] In addition, as the pH of the wastewater is lowered to 4-6, unreactive phosphorus present in the wastewater is converted into orthophosphoric acid ions that can pass through the anion exchange membrane (AEM), thereby improving the phosphate ion separation efficiency of the wastewater.

[0044] Meanwhile, the acid solution supplied to the wastewater pretreatment tank (110) to lower the pH of the wastewater is supplied from the phosphoric acid concentration tank (150). That is, the phosphoric acid concentration tank (150) is supplied to the wastewater pretreatment tank (110) as an acid solution to lower the pH of the wastewater. The phosphoric acid concentration tank can be used to lower the pH of the wastewater to about 4 to 6.

[0045] The wastewater supply tank (120) receives wastewater with a lowered pH from the wastewater pretreatment and supplies it to the bipolar membrane electrodialysis device (130). Specifically, the wastewater from the wastewater supply tank (120) is supplied to the salt zone (S) (132) of the bipolar membrane electrodialysis device (130).

[0046] The above bipolar membrane electrodialysis device (130) serves to separate ammonium ions and phosphate ions contained in wastewater. Specifically, as illustrated in FIG. 2, the above bipolar membrane electrodialysis device (130) is equipped with a reaction tank.

[0047] At both ends of the reactor, an anode (+) and a cathode (-) are provided, to which power is applied for water decomposition and ion movement of the bipolar membrane (BM), and a bipolar membrane (BM), an anion exchange membrane (AEM), and a cation exchange membrane (CEM) are sequentially spaced and arranged between the anode (+) and the cathode (-).

[0048] The space between the bipolar membrane (BM) and the anion exchange membrane (AEM) is defined as an acid zone (A) (131), the space between the anion exchange membrane (AEM) and the cation exchange membrane (CEM) is defined as a salt zone (S) (132), and the space between the cation exchange membrane (CEM) and the bipolar membrane (BM) is defined as a base zone (B) (133).

[0049] The sequential arrangement of the above bipolar membrane (BM), anion exchange membrane (AEM), and cation exchange membrane (CEM) can be repeated within the reactor, and accordingly, the acid region (A) (131), salt region (S) (132), and base region (B) (133) can also be repeated within the reactor.

[0050] Wastewater from the wastewater supply tank (120) is supplied to the salt zone (S) (132) of the bipolar membrane electrodialysis device (130), and ammonium ions and phosphate ions contained in the wastewater are simultaneously separated by water decomposition of the bipolar membrane (BM), ion exchange operations of the bipolar membrane (BM), anion exchange membrane (AEM), and cation exchange membrane (CEM), and chemical reactions in each zone.

[0051] Looking at this specifically, when water exists in the acid region (A) (131) and the base region (B) (133) and wastewater is supplied to the salt region (S) (132), when power is applied to the anode (+) and cathode (-), water is decomposed in the bipolar membrane (BM) to form hydrogen ions (H + ) and hydroxide ions (OH - ) is generated. To be precise, a bipolar membrane (BM) is a membrane formed by joining an anion exchange membrane and a cation exchange membrane, and water is decomposed at the junction of the anion exchange membrane and the cation exchange membrane to form hydrogen ions (H + ) and hydroxide ions (OH - ) is generated. Hydrogen ions (H ) generated by the decomposition of water + ) and hydroxide ions (OH - ) are moved through the anion exchange membrane and cation exchange membrane, respectively.

[0052]

[0053] *Hydrogen ion (H + ) is the area where hydrogen ions (H + ) is defined as the acid region (A)(131) as the pH is lowered by hydroxide ions (OH - ) is the area where hydroxide ions (OH - ) is defined as the base region (B)(133) as the pH increases.

[0054] In this way, hydrogen ions (H) are produced by the decomposition of water. + ), hydroxide ion (OH - ) are moved to the acid region (A) (131) and the base region (B) (133), respectively, and the ammonium ion (NH4) present in the wastewater + ) and phosphate ion (PO3 4- ) also moves through the cation exchange membrane (CEM) and the anion exchange membrane (AEM). That is, the ammonium ion (NH4) present in the wastewater + ) passes through the cation exchange membrane (CEM) and moves to the base region (B) (133), and phosphate ions (PO3) present in the wastewater 4- ) passes through the anion exchange membrane (AEM) and moves to the acid region (A) (131).

[0055] Next, the ammonium ion (NH4) moved to the base region (B) (133) + ) is a hydroxide ion (OH) that is moved to the base region (B)(133) by the production of water. - ) reacts with ammonia (NH3) and is converted into phosphate ion (PO3) that moves to the acid region (A) (131). 4- ) is a hydrogen ion (H) that has moved to the acid region (A) (131) by the production of water. + ) reacts with hydrogen phosphate ion (HPO4) 2- ), dihydrogen phosphate ion (H2PO4 - ), phosphoric acid (H3PO4), etc.

[0056] As described above, by the operation of the bipolar membrane electrodialysis device (130), ammonium ions and phosphate ions contained in the wastewater are simultaneously separated. At this time, as described above, as the pH of the wastewater is lowered to 4 to 6 in the wastewater pretreatment tank (110), the ammonium ion / ammonia ratio in the wastewater increases, and as the dissolved phosphorus is converted into the form of orthophosphate ions, the simultaneous separation efficiency of ammonium ions and phosphate ions in the bipolar membrane electrodialysis device (130) is improved. In addition, as carbonate ions in the wastewater are removed in advance by adjusting the pH in the wastewater pretreatment tank (110), the electrical conductivity of the bipolar membrane electrodialysis device (130) can be increased, thereby increasing the separation speed of the ions.

[0057] Through the above process, ammonia (NH3) is produced and concentrated in the base region (B) (133), and phosphoric acid is produced and concentrated in the acid region (A) (131). The ammonia concentrate produced in the base region (B) (133) is moved to the ammonia concentration tank (140), and the phosphoric acid concentrate produced in the acid region (A) (131) is moved to the phosphoric acid concentration tank (150).

[0058] The ammonia concentrate from the ammonia concentration tank (140) is transferred to the ammonia recovery device (160), and the ammonia recovery device (160) recovers ammonia from the ammonia concentrate. At this time, the ammonia recovery device (160) may be configured with an ammonia degassing tank or a gas separation membrane that induces separation and permeation of ammonia.

[0059] The phosphoric acid concentrate from the phosphoric acid concentration tank (150) is also transferred to the phosphoric acid recovery device (170) for phosphoric acid recovery. The phosphoric acid recovery device (170) generates calcium orthophosphate through a reaction between the phosphoric acid concentrate and calcium salt. Meanwhile, as described above, the phosphoric acid concentrate from the phosphoric acid concentration tank (150) is supplied to the wastewater pretreatment tank (110) and also functions as an acid solution that lowers the pH of the wastewater.

[0060] Wastewater from which ammonium ions and phosphate ions have been removed in the salt zone (S) (132) of the bipolar membrane electrodialysis device (130) is circulated to the wastewater supply tank (120), and wastewater from which ammonium ions and phosphate ions have been removed above a certain concentration is discharged to the outside.

[0061] Above, a device capable of simultaneous separation and recovery of ammonia and phosphoric acid using a bipolar membrane electrodialysis device according to one embodiment of the present invention has been described.

[0062] Meanwhile, the above-described bipolar membrane electrodialysis device (130) has a three-chamber structure of an acid region (A) (131), a base region (B) (132), and a salt region (S) (133). According to a modified embodiment of the present invention, a two-chamber structure bipolar membrane electrodialysis device can be configured, and simultaneous separation of ammonia and phosphoric acid can be realized based on this. Hereinafter, the first modified embodiment and the second modified embodiment will be described. The first modified embodiment is an embodiment in which a bipolar membrane (BM) and an anion exchange membrane (AEM) are applied to divide two chambers of an acid region (A) and a base region (B), and the second modified embodiment is an embodiment in which a bipolar membrane (BM) and a cation exchange membrane (CEM) are applied to divide two chambers of an acid region (A) and a base region (B).

[0063] First, let us explain the first modified embodiment.

[0064] Referring to Fig. 3, bipolar membranes (BM) and anion exchange membranes (AEM) are alternately and repeatedly arranged within the reactor. The space between the bipolar membrane (BM) and the anion exchange membrane (AEM) is defined as an acid region (A) (231), and the space between the anion exchange membrane (AEM) and the bipolar membrane (BM) is defined as a base region (B) (232). In addition, an anode (+) and a cathode (-) are respectively provided at both ends of the reactor.

[0065] Wastewater from the wastewater supply tank (120) is supplied to the base zone (B) (232), and ammonium ions and phosphate ions contained in the wastewater are simultaneously separated by water decomposition of the bipolar membrane (BM), ion exchange operation of the bipolar membrane (BM) and anion exchange membrane (AEM), and chemical reactions in each zone.

[0066] When power is applied to the anode (+) and cathode (-) while water exists in the acid region (A) (231) and wastewater is supplied to the base region (S) (232), water is decomposed in the bipolar membrane (BM) to form hydrogen ions (H + ) and hydroxide ions (OH - ) is generated, and hydrogen ions (H + ) is moved to the acid region (A)(231) and hydroxide ions (OH - ) is moved to the base region (B) (232). In addition, phosphate ions (PO3) present in wastewater 4- ) passes through the anion exchange membrane (AEM) and moves to the acid region (A) (231), and the ammonium ion (NH4) of the wastewater + ) is located in the base region (B)(232).

[0067] Ammonium ion (NH4) present in the base region (B)(232) + ) is a hydroxide ion (OH - ) reacts with ammonia (NH3) and is converted into phosphate ion (PO3) that moves to the acid region (A) (231). 4- ) is a hydrogen ion (H + ) reacts with hydrogen phosphate ion (HPO4) 2- ), dihydrogen phosphate ion (H2PO4 - ), phosphoric acid (H3PO4), etc.

[0068] Through the above process, ammonia (NH3) is produced and concentrated in the base region (B) (232), and phosphoric acid is produced and concentrated in the acid region (A) (231). The ammonia concentrate produced in the base region (B) (232) is moved to the ammonia concentration tank (140), and the phosphoric acid concentrate produced in the acid region (A) (231) is moved to the phosphoric acid concentration tank (150).

[0069] Through the first modified embodiment above, simultaneous separation and recovery of ammonium ions and phosphate ions contained in wastewater is possible.

[0070] Next, we will describe the second modified embodiment.

[0071] Referring to Fig. 4, bipolar membranes (BM) and cation exchange membranes (CEM) are alternately and repeatedly arranged within the reactor. The space between the bipolar membrane (BM) and the cation exchange membrane (CEM) is defined as an acid region (A) (331), and the space between the cation exchange membrane (CEM) and the bipolar membrane (BM) is defined as a base region (B) (332). In addition, an anode (+) and a cathode (-) are respectively provided at both ends of the reactor.

[0072] Wastewater from the wastewater supply tank (120) is supplied to the acid zone (A) (331), and ammonium ions and phosphate ions contained in the wastewater are simultaneously separated by water decomposition of the bipolar membrane (BM), ion exchange operation of the bipolar membrane (BM) and cation exchange membrane (CEM), and chemical reactions in each zone.

[0073] When power is applied to the anode (+) and cathode (-) while water exists in the base region (B) (332) and wastewater is supplied to the acid region (A) (331), water is decomposed in the bipolar membrane (BM) to form hydrogen ions (H + ) and hydroxide ions (OH - ) is generated, and hydrogen ions (H + ) is moved to the acid region (A)(331) and hydroxide ions (OH - ) is moved to the base region (B) (332). In addition, ammonium ion (NH4) present in wastewater + ) passes through the cation exchange membrane (CEM) and moves to the base region (B) (332), and the phosphate ion (PO3) of the wastewater 4- ) will remain in the mountain area (A).

[0074] Ammonium ion (NH4) moved to the base region (B)(332) + ) is a hydroxide ion (OH -) reacts with ammonia (NH3) and is converted into phosphate ion (PO3) present in the acid region (A) (331). 4- ) is a hydrogen ion (H + ) reacts with hydrogen phosphate ion (HPO4) 2- ), dihydrogen phosphate ion (H2PO4 - ), phosphoric acid (H3PO4), etc.

[0075] Through the above process, ammonia (NH3) is produced and concentrated in the base region (B) (332), and phosphoric acid is produced and concentrated in the acid region (A) (331). The ammonia concentrate produced in the base region (B) (332) is moved to the ammonia concentration tank (140), and the phosphoric acid concentrate produced in the acid region (A) (331) is moved to the phosphoric acid concentration tank (150).

[0076] Above, a device capable of simultaneous separation and recovery of ammonia and phosphoric acid using a bipolar membrane electrodialysis device according to one embodiment and a modified embodiment of the present invention has been described. Hereinafter, the present invention will be described in more detail through experimental examples.

[0077] Experimental Example 1: Removal and Recovery of Ammonia and Phosphoric Acid from Synthetic Wastewater

[0078] The removal and recovery efficiency of ammonia nitrogen and phosphoric acid was investigated using a three-chamber bipolar membrane electrodialysis device based on one embodiment of the present invention, targeting ammonium phosphate synthetic wastewater. The initial ammonia concentration of the wastewater (feed) was 2600 mg / L, and the initial phosphorus concentration of the wastewater was 2860 mg / L. A current of 6 V per pair was applied to the three-chamber bipolar membrane electrodialysis device.

[0079] As a result of the experiment, referring to Fig. 5a, the initial ammonia concentration of 2600 mg / L in the wastewater (feed) was reduced to 3 mg / L after 120 minutes, confirming that more than 99% of the ammonia was removed. In addition, the ammonia concentration recovered in the base region was 2020 mg / L, indicating that approximately 78% was recovered.

[0080] In the case of phosphorus (see Fig. 5b), the initial phosphorus concentration in the feed decreased from 2860 mg / L to 18 mg / L after 120 minutes, confirming that more than 99% of phosphorus was removed. In addition, the phosphorus concentration recovered in the acid region was 2880 mg / L, indicating 100% recovery.

[0081] Experimental Example 2: Removal and Recovery of Ammonia from Livestock Manure Digestion

[0082] The removal and recovery efficiency of ammonia nitrogen was investigated using a three-chamber bipolar membrane electrodialysis device based on one embodiment of the present invention, targeting livestock manure digestate. The initial ammonia concentration of the wastewater (feed) was 5000 mg / L, and a current of 6 V per pair was applied to the three-chamber bipolar membrane electrodialysis device.

[0083] As a result of the experiment, referring to Fig. 6, the initial ammonia concentration of 5000 mg / L in the wastewater (feed) decreased to 349 mg / L after 240 minutes, confirming that 93% of the ammonia was removed. In addition, the ammonia concentration recovered in the base region was 3895 mg / L, indicating that approximately 78% was recovered.

[0084] Experimental Example 3: Ammonia Removal Characteristics Depending on Wastewater Pretreatment

[0085] The ammonia removal characteristics of the livestock manure digestate used in Experimental Example 2 were investigated according to the presence or absence of wastewater pretreatment. The pH of the non-pretreated wastewater was 8, and the pH of the pretreated wastewater (acid-treated) was 4. A current of 6 V per pair was applied to a three-chamber bipolar membrane electrodialysis device.

[0086] As shown in Fig. 7, the experimental results show that approximately 90% of the ammonia was removed from the non-pretreated wastewater after 240 minutes, whereas the acid-treated wastewater achieved 90% ammonia removal after only 120 minutes. These results demonstrate that the ammonia removal rate is significantly enhanced by the pretreatment of the wastewater.

[0087] [Explanation of symbols]

[0088] 110: Wastewater pretreatment tank 120: Wastewater supply tank

[0089] 130, 230, 330: Bipolar membrane electrodialysis device

[0090] 131: Mountain area (A) 132: Salt area (S)

[0091] 133: Base area (B) 140: Ammonia concentration tank

[0092] 150: Phosphoric acid concentration tank 160: Ammonia recovery device

[0093] 170: Phosphate recovery device

Claims

1. Wastewater pretreatment tank to lower the pH of wastewater; A wastewater supply tank that receives pretreated wastewater from a wastewater pretreatment tank and supplies it to a bipolar membrane electrodialysis device; A bipolar membrane electrodialysis device that simultaneously separates ammonia and phosphoric acid contained in wastewater; An ammonia concentration tank that supplies and stores ammonia concentrate generated in the base region (B) of a bipolar membrane electrodialysis device from the base region (B); and A device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device, characterized in that it comprises a phosphoric acid concentration tank that receives and stores the phosphoric acid concentrate produced in the acid zone (A) of the bipolar membrane electrodialysis device from the acid zone (A).

2. In the first paragraph, the bipolar membrane electrodialysis device has a reaction tank, An anode (+) and a cathode (-) are provided on each end of the reactor, and a bipolar membrane (BM), an anion exchange membrane (AEM), and a cation exchange membrane (CEM) are sequentially placed between the anode (+) and the cathode (-). The space between the bipolar membrane (BM) and the anion exchange membrane (AEM) is defined as the acid region (A), the space between the anion exchange membrane (AEM) and the cation exchange membrane (CEM) is defined as the salt region (S), and the space between the cation exchange membrane (CEM) and the bipolar membrane (BM) is defined as the base region (B). A device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device, characterized in that wastewater from a wastewater supply tank is supplied to a salt zone (S).

3. In the second paragraph, hydrogen ions (H) generated by water decomposition of the bipolar membrane (BM) + ), hydroxide ion (OH - ) are moved to the acid region (A) and base region (B), respectively. Ammonium ion (NH) contained in wastewater supplied to the salt zone (S) 4 + ) passes through the cation exchange membrane (CEM) and moves to the base zone (B), and the phosphate ion (PO ) contained in the wastewater supplied to the salt zone (S) 3 4- ) passes through the anion exchange membrane (AEM) and moves to the acid region (A). Ammonium ion (NH) moved to the base region (B) 4 + ) is a hydroxide ion (OH - ) reacts with ammonia (NH 3 ) is converted to phosphate ion (PO ) and moved to the acid region (A). 3 4- ) is a hydrogen ion (H + ) reacts with hydrogen phosphate ion (HPO) 4 2- ), dihydrogen phosphate ion (H 2 PO 4 - ), phosphoric acid (H 3 PO 4 ) A device capable of simultaneous separation and recovery of ammonia and phosphoric acid using a bipolar membrane electrodialysis device characterized in that the ammonia and phosphoric acid are converted into either one of the following.

4. A device capable of simultaneous separation and recovery of ammonia and phosphoric acid using a bipolar membrane electrodialysis device, characterized in that in the third paragraph, the ammonia concentrate produced in the base region (B) is moved to an ammonia concentrate tank, and the phosphoric acid concentrate produced in the acid region (A) is moved to a phosphoric acid concentrate tank.

5. In paragraph 4, the phosphoric acid concentrate from the phosphoric acid concentration tank is supplied to the wastewater pretreatment tank, and the pH of the wastewater in the wastewater pretreatment tank is adjusted to 4 to 6. A device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device, characterized in that the pH of wastewater is adjusted to 4 to 6 in a wastewater pretreatment tank, thereby removing carbonate ions in the wastewater, increasing the ammonium ion / ammonia ratio in the wastewater, and converting non-reactive phosphorus in the wastewater into the form of orthophosphate ions.

6. In the first paragraph, the bipolar membrane electrodialysis device has a reaction tank, An anode (+) and a cathode (-) are provided on each end of the reactor, and a bipolar membrane (BM) and anion exchange membrane (AEM) are alternately and repeatedly arranged between the anode (+) and the cathode (-). The space between the bipolar membrane (BM) and the anion exchange membrane (AEM) is defined as an acid region (A), and the space between the anion exchange membrane (AEM) and the bipolar membrane (BM) is defined as a base region (B). A device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device, characterized in that wastewater from a wastewater supply tank is supplied to a base zone (B).

7. In paragraph 6, hydrogen ions (H) generated by water decomposition of the bipolar membrane (BM) + ), hydroxide ion (OH - ) are moved to the acid region (A) and base region (B), respectively. Phosphate ion (PO) contained in wastewater supplied to the base area (B) 3 4- ) passes through the anion exchange membrane (AEM) and moves to the acid zone (A), and ammonium ion (NH) of wastewater supplied to the base zone (B) 4 + ) is located in the base region (B). Ammonium ion (NH) present in the base region (B) 4 + ) is a hydroxide ion (OH - ) reacts with ammonia (NH 3 ) is converted to phosphate ion (PO ) and moved to the acid region (A). 3 4- ) is a hydrogen ion (H + ) reacts with hydrogen phosphate ion (HPO) 4 2- ), dihydrogen phosphate ion (H 2 PO 4 - ), phosphoric acid (H 3 PO 4 ) is converted to one of the following: A device capable of simultaneous separation and recovery of ammonia and phosphoric acid using a bipolar membrane electrodialysis device, characterized in that the ammonia concentrate produced in the base region (B) is moved to an ammonia concentrate tank, and the phosphoric acid concentrate produced in the acid region (A) is moved to a phosphoric acid concentrate tank.

8. In the first paragraph, the bipolar membrane electrodialysis device has a reaction tank, An anode (+) and a cathode (-) are provided on each end of the reactor, and a bipolar membrane (BM) and a cation exchange membrane (CEM) are alternately and repeatedly arranged between the anode (+) and the cathode (-). The space between the bipolar membrane (BM) and the cation exchange membrane (CEM) is defined as an acid region (A), and the space between the cation exchange membrane (CEM) and the bipolar membrane (BM) is defined as a base region (B). A device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device, characterized in that wastewater from a wastewater supply tank is supplied to an acid zone (A).

9. In paragraph 8, hydrogen ions (H) generated by water decomposition of the bipolar membrane (BM) + ), hydroxide ion (OH - ) are moved to the acid region (A) and base region (B), respectively. Ammonium ion (NH) contained in wastewater supplied to the mountain area (A) 4 + ) passes through the cation exchange membrane (CEM) and moves to the base zone (B), and the phosphate ion (PO ) contained in the wastewater supplied to the acid zone (A) 3 4- ) will remain in the mountain area (A). Ammonium ion (NH) moved to the base region (B) 4 + ) is a hydroxide ion (OH - ) reacts with ammonia (NH 3 ) is converted to phosphate ion (PO ) present in the acid region (A). 3 4- ) is a hydrogen ion (H + ) reacts with hydrogen phosphate ion (HPO) 4 2- ), dihydrogen phosphate ion (H 2 PO 4 - ), phosphoric acid (H 3 PO 4 ) is converted to one of the following: A device capable of simultaneous separation and recovery of ammonia and phosphoric acid using a bipolar membrane electrodialysis device, characterized in that the ammonia concentrate produced in the base region (B) is moved to an ammonia concentrate tank, and the phosphoric acid concentrate produced in the acid region (A) is moved to a phosphoric acid concentrate tank.

10. In paragraph 1, the phosphoric acid concentrate from the phosphoric acid concentration tank is delivered to the phosphoric acid recovery device. The phosphate recovery device is a device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device characterized by producing calcium phosphate through the reaction of a phosphoric acid concentrate and a calcium salt.

11. In paragraph 1, the ammonia concentrate from the ammonia concentration tank is delivered to the ammonia recovery device. An ammonia recovery device is a device capable of simultaneously separating and recovering ammonia and phosphoric acid using a bipolar membrane electrodialysis device characterized in that it recovers ammonia from an ammonia concentrate using an ammonia stripper or a gas separation membrane that induces separation and permeation of ammonia.

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