Iron phosphate production wastewater treatment and cyclic production system

Abstract

The utility model provides an iron phosphate production wastewater treatment and circular production system, which belongs to the technical field of resource recovery technology and circular economy, and comprises a wastewater treatment module, a bipolar membrane electrodialysis system, a second membrane treatment system and an evaporation system which are sequentially connected along a wastewater flow direction, wherein the wastewater treatment module comprises at least one wastewater treatment unit, and each wastewater treatment unit comprises a pretreatment system and a first membrane treatment system which are sequentially distributed in the wastewater flow direction; the bipolar membrane electrodialysis system is communicated with the pretreatment system; the bipolar membrane electrodialysis system is communicated with the first membrane treatment system. The method is beneficial to reducing the input of exogenous sulfuric acid and ammonia water, and achieves the effects of circular economy and benefit enhancement.

Description

Technical Field

[0001] The present application relates to resource recovery technology and circular economy technology, and specifically to an iron phosphate production wastewater treatment and recycling production system. Background Art

[0002] A large amount of iron phosphate wastewater is generated during the production process of iron phosphate. The iron phosphate wastewater contains heavy metals, nitrogen, phosphorus, and other inorganic salts. Direct discharge will seriously pollute the environment. Therefore, the wastewater from iron phosphate production needs to be strictly treated to meet the emission standards.

[0003] In the related art, the iron phosphate wastewater treatment process generally includes pretreatment, membrane separation, evaporation treatment and recovery treatment. The wastewater generated during the production of ferric phosphate contains a large amount of suspended solids, excessive ammonia nitrogen, total phosphorus and other organic and inorganic substances. The main purpose of pretreatment is to remove these impurities and provide good conditions for subsequent treatment. A large amount of ammonia water and sulfuric acid need to be added during the pretreatment process, and finally converted into by-product ammonium sulfate; the pretreated water is further subjected to membrane separation. The membrane separation process is a permeability-based separation method that has a high efficiency in separating and removing organic and ionic pollutants in ferric phosphate wastewater. Driven by the pressure of the reverse osmosis membrane, the membrane separation technology can remove soluble salts and organic matter in the wastewater to achieve wastewater purification and recycling; then, through evaporation treatment, the water in the wastewater can be evaporated, leaving concentrated salts and organic matter. Evaporation treatment can use MVR evaporators, multi-effect evaporators and other equipment, as well as mixed salt evaporators designed for the characteristics of ferric phosphate wastewater to treat the evaporator concentrate; the wastewater that has completed the previous treatment steps can finally be recycled. Recycling is the final link in the treatment of ferric phosphate wastewater, aiming to achieve the recovery and resource utilization of useful substances in the wastewater.

[0004] Because the treatment of iron phosphate wastewater requires a large amount of exogenous ammonia and sulfuric acid, the cost of the reagents will increase, while the production line will be lengthened and the cost will also be high. Utility Model Content

[0005] In view of the technical problems existing in the background technology, the present application provides a ferric phosphate production wastewater treatment and recycling production system, aiming to achieve a circular economy, enhance efficiency, reduce the input of exogenous sulfuric acid and ammonia water, and reduce the introduction of impurity elements.

[0006] The embodiment of the present application provides a ferric phosphate production wastewater treatment and circulation production system, comprising a wastewater treatment module, a bipolar membrane electrodialysis system, a second membrane treatment system and an evaporation system connected in sequence along the wastewater flow direction; wherein the wastewater treatment module comprises at least one wastewater treatment unit, and the wastewater treatment unit comprises a pretreatment system and a first membrane treatment system distributed in sequence along the wastewater flow direction;

[0007] The bipolar membrane electrodialysis system is connected to the pretreatment system;

[0008] The bipolar membrane electrodialysis system is in communication with the first membrane treatment system.

[0009] In the technical solution of the embodiment of the present application, wastewater passes through a wastewater treatment module, a bipolar membrane electrodialysis system, a second membrane treatment system and an evaporation system in sequence. After being treated by the wastewater treatment module and the bipolar membrane electrodialysis system, impurities in the wastewater are removed, and then the wastewater is evaporated and crystallized in the evaporation system to obtain the final by-product ammonium sulfate. During the process, the dilute ammonia water and dilute sulfuric acid decomposed in the bipolar membrane electrodialysis system are respectively refluxed to the pretreatment system and the first membrane treatment system for use, thereby effectively realizing a resource recycling economy, achieving self-sufficiency and enhancing benefits.

[0010] In some embodiments, the bipolar membrane electrodialysis system has a byproduct discharge port.

[0011] In this embodiment, the remaining dilute sulfuric acid in the bipolar membrane electrodialysis system can be used as a raw material in other production workshops through the by-product discharge port, effectively saving production costs.

[0012] In some embodiments, the wastewater treatment module includes a plurality of wastewater treatment units connected in sequence, and among the plurality of wastewater treatment units, an oxidant inlet is provided on the pretreatment system of the wastewater treatment unit located most downstream.

[0013] In this embodiment, multiple wastewater treatment units are set up and an oxidant is added to the pretreatment system of the most downstream wastewater treatment unit, so that the wastewater can be effectively removed multiple times and the introduction of more impurities is avoided, manganese ions are removed, and poisoning and damage to the bipolar membrane electrodialysis system are avoided.

[0014] In some embodiments, two wastewater treatment units are provided, and the oxidant inlet is provided on a pretreatment system located downstream of the two wastewater treatment units.

[0015] In this embodiment, by providing two wastewater treatment units, the system has a high degree of integration and a high level of intelligence.

[0016] In some embodiments, the pretreatment system of the wastewater treatment unit located most upstream is configured as an open reaction precipitation system, and the pretreatment system of the wastewater treatment unit located most downstream is configured as a closed reaction precipitation system.

[0017] In this embodiment, the pretreatment system in the most upstream wastewater treatment unit is set as an open reaction precipitation system, which is beneficial to heat dissipation; the pretreatment system in the most downstream wastewater treatment unit is set as a closed reaction precipitation system to avoid ammonia escape.

[0018] In some embodiments, the first membrane treatment system of the wastewater treatment unit located most upstream includes a fiber ball filter, a first ultrafiltration device and a first reverse osmosis device connected in sequence along the wastewater flow direction, and the bipolar membrane electrodialysis system is connected to the first ultrafiltration device.

[0019] In this embodiment, impurities in water are filtered layer by layer through the fiber ball filter, the first ultrafiltration device and the first reverse osmosis device, thereby improving the wastewater treatment efficiency.

[0020] In some embodiments, the first membrane treatment system of the wastewater treatment unit located at the most downstream includes a multi-media filter, a second ultrafiltration device and a second reverse osmosis device connected in sequence along the wastewater flow direction, and the bipolar membrane electrodialysis system is connected to the second ultrafiltration device.

[0021] In this embodiment, the wastewater that has undergone one cycle treatment is further subjected to deep treatment through a multi-media filter, a second ultrafiltration device, and a second reverse osmosis device, thereby improving the quality of wastewater treatment.

[0022] In some embodiments, the second membrane treatment system includes a third reverse osmosis device.

[0023] In this embodiment, the third reverse osmosis device is used to minimize the impurity content of water flowing into the evaporation system, thereby improving the quality of ammonium sulfate.

[0024] In some embodiments, a third membrane treatment system is further included, and the third membrane treatment system is respectively connected to the first membrane treatment system of the wastewater treatment unit located most upstream, the first membrane treatment system of the wastewater treatment unit located most downstream, and the second membrane treatment system.

[0025] In this embodiment, by setting up the third membrane treatment system, the water in the upstream first membrane treatment system, the downstream first membrane treatment system and the second membrane treatment system are respectively subjected to a final filtration treatment to obtain high-quality pure water, which is reused in iron phosphate production, saving a large amount of water resources.

[0026] In some embodiments, the third membrane treatment system comprises a reverse osmosis device.

[0027] In this embodiment, trace dissolved matter in water is effectively removed by the reverse osmosis device.

[0028] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 This is a schematic diagram of the overall process structure of the iron phosphate production wastewater treatment and recycling production system in the embodiment of the present application;

[0031] Figure 2 This is a schematic diagram of a first membrane treatment system for illustrating a wastewater treatment unit located upstream in an embodiment of the present application;

[0032] Figure 3 This is a schematic diagram of a first membrane treatment system for illustrating a wastewater treatment unit located downstream in an embodiment of the present application;

[0033] Explanation of the accompanying drawings: 1. first pipeline; 20. pretreatment system; 21. first membrane treatment system; 200. fiber ball filter; 201. first ultrafiltration device; 202. first reverse osmosis device; 203. multi-media filter; 204. second ultrafiltration device; 205. second reverse osmosis device; 3. bipolar membrane electrodialysis system; 4. second membrane treatment system; 5. evaporation system; 6. second pipeline; 7. third pipeline; 8. fourth pipeline; 9. third membrane treatment system. DETAILED DESCRIPTION

[0034] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0036] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0037] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0038] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0039] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0040] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0041] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0042] A large amount of iron phosphate wastewater is generated during the production process of iron phosphate, and wastewater treatment plays a very important role in ecological development and industrial production. The core wastewater treatment steps in related technologies are pretreatment, membrane separation, evaporation treatment and recovery treatment. In this process, 1 ton of iron phosphate products are produced. The wastewater treatment needs to add 0.4 tons of ammonia water with a concentration of 22% and 0.2 tons of sulfuric acid with a concentration of 98%. To obtain 1 ton of ammonium sulfate, the evaporator needs to evaporate 7.3 tons of water. Therefore, the process requires a large amount of exogenous ammonia water and sulfuric acid, which increases the cost of the reagents and introduces other impurities, affecting the quality of the by-product ammonium sulfate. Secondly, the increase in the by-product ammonium sulfate leads to high membrane system treatment costs, high MVR evaporation volume, and high energy consumption.

[0043] In order to solve the technical problem of high cost of iron phosphate wastewater treatment, the present application provides an iron phosphate production wastewater treatment and recycling production system, referring to Figure 1-Figure 3 , wherein the wastewater is transported through the first pipeline 1, and then sequentially treated by the wastewater treatment module, the bipolar membrane electrodialysis system 3, the second membrane treatment system 4 and the evaporation system 5, so that the wastewater is finally discharged as a by-product of ammonium sulfate. Wherein, the wastewater treatment module includes at least one wastewater treatment unit, and the wastewater treatment unit includes a pretreatment system 20 and a first membrane treatment system 21 connected along the flow direction of the wastewater. When the wastewater flows through at least one pretreatment system 20 and the first membrane treatment system 21, the oxidant is added from the oxidant injection port of one of the pretreatment systems 20. The wastewater flowing into the bipolar membrane electrodialysis system 3 is decomposed into dilute ammonia water and dilute sulfuric acid under the action of the electric field, and refluxed to the pretreatment system 20 and the first membrane treatment system 21 for recycling. Therefore, in the present application, the production of 1 ton of ferric phosphate product can obtain 0.6 tons of ammonium sulfate, 2.5 tons of dilute sulfuric acid with a concentration of 10%, and 0.88 tons of dilute ammonia water with a concentration of 10%. The evaporation system 5 evaporates 3 tons of water; 0.88 tons of dilute ammonia water with a concentration of 10% are all used in the wastewater treatment module without being discharged, 2 tons of 2.5 tons of dilute sulfuric acid with a concentration of 10% are used in the pretreatment system 20, and the remaining 0.5 tons of dilute sulfuric acid by-product with a concentration of 10% is used as a raw material for other production units, effectively reducing the use of exogenous resources and realizing a circular economy.

[0044] Please refer to Figure 1 , Figure 1 The overall process structure diagram of the iron phosphate production wastewater treatment and recycling production system provided in one embodiment of the present application, in this embodiment, the system includes:

[0045] The wastewater treatment modules, bipolar membrane electrodialysis system 3, second membrane treatment system 4 and evaporation system 5 are connected in sequence along the wastewater flow direction; in the present application, wastewater transportation includes but is not limited to the use of a first pipeline 1, and the first pipeline 1 is not limited to being made of a PE pipe. The PE pipe is a new type of wastewater pipe material with the characteristics of light weight, corrosion resistance, tensile strength and wear resistance, and is suitable for urban drainage systems, factory sewage systems, rural biogas projects and other fields.

[0046] Among them, the wastewater treatment module includes at least one wastewater treatment unit, and the wastewater treatment unit includes a pretreatment system 20 and a first membrane treatment system 21 connected along the flow direction of the wastewater; thus, the wastewater enters the pretreatment system 20 through the first pipeline 1, and in the pretreatment system 20, the wastewater is first impurity-removed by adding exogenous ammonia water, and the metal iron, magnesium, manganese, and calcium contained in the wastewater are removed by impurity removal. The impurity removal control condition is PH5-9, the first pretreatment impurity removal is preferably PH5.5-6.5, and the secondary pretreatment impurity removal is preferably PH8.5-9. The outlet of the pretreatment system 20 is connected to the inlet of the first membrane treatment system 21. In the first membrane treatment system 21, by adding exogenous sulfuric acid, the Langelier saturation index is reduced and the scaling risk of the membrane system is reduced. The control condition is PH5-6, preferably 5.5. At the same time, the wastewater after the first impurity removal is concentrated and purified by the first membrane treatment system 21 to reduce the amount of sewage. The concentration of ammonium sulfate in the concentrated wastewater is about 10%.

[0047] In the present application, the bipolar membrane electrodialysis system 3 has an acid chamber outlet, an alkali chamber outlet and a light brine outlet; the acid concentration of the acid chamber outlet is 10%, the alkali concentration of the alkali chamber outlet is 10%, and the light brine concentration is about 2%; the light brine outlet is connected to the second membrane treatment system 4, and the second membrane treatment system 4 is used for filtering treatment, and the second membrane treatment system 4 includes a third reverse osmosis device, and the core of the third reverse osmosis device is to use a reverse osmosis membrane (RO membrane) with a very small pore size to filter raw water. When the device is working, the wastewater is first pre-treated by a fine filter, and then pressurized by a pump to make the water pass through the reverse osmosis membrane under pressure. In this process, higher concentration water is converted into low concentration water, and at the same time, industrial pollutants, heavy metals, bacteria, viruses and other impurities mixed in the water are effectively isolated.

[0048] The water that has completed the reverse osmosis treatment is finally evaporated and crystallized in the evaporation system 5 to obtain the final byproduct ammonium sulfate, which is sold as fertilizer; the evaporation system 5 includes but is not limited to the use of MVR evaporation and crystallization technology. The core of MVR evaporation and crystallization technology is to reuse the energy of the secondary steam generated by the evaporator itself, thereby reducing the demand for external energy. This technology compresses the secondary steam generated by evaporation through a steam compressor, increases the pressure and temperature of the steam, and enables it to be used as a heat source to replace fresh steam to achieve cyclic evaporation.

[0049] The bipolar membrane electrodialysis system 3 is connected to the pretreatment system 20, and the communication method includes but is not limited to using a second pipeline 6, and the two ends of the second pipeline 6 are respectively connected to the bipolar membrane electrodialysis system 3 and the pretreatment system 20;

[0050] The bipolar membrane electrodialysis system 3 is connected to the first membrane treatment system 21 , and the connection method includes but is not limited to using a third pipeline 7 , and the two ends of the third pipeline 7 are respectively connected to the bipolar membrane electrodialysis system 3 and the first membrane treatment system 21 .

[0051] In the pretreatment system 20, exogenous ammonia water is added to carry out the first impurity removal of the wastewater, and the metal iron, magnesium, manganese and calcium contained in the wastewater are removed. In the first membrane treatment system 21, exogenous sulfuric acid is added to reduce the Langelier index and reduce the risk of wastewater scaling. After being concentrated by the first membrane treatment system 21, the wastewater enters the bipolar membrane electrodialysis system 3, and a part of the ammonium sulfate is decomposed into dilute ammonia water and dilute sulfuric acid under the action of the bipolar membrane and the electric field. The dilute ammonia water flows back to the pretreatment system 20 through the second pipeline 6 for recycling, and the dilute sulfuric acid flows back to the first membrane treatment system 21 through the third pipeline 7 for reuse. After the dilute sulfuric acid and dilute ammonia water begin to be recycled, the addition of exogenous ammonia water and sulfuric acid is reduced, which saves production costs. Because the circular economy is realized, the supply chain risk and financial pressure are reduced.

[0052] Further, in the embodiments of the present application, Figure 1 As shown, a plurality of wastewater treatment units are provided, wherein the pretreatment system 20 of the wastewater treatment unit located at the most downstream is provided with an oxidant injection port, and the oxidant added from the oxidant injection port includes but is not limited to hydrogen peroxide, and the ORP is controlled at 400-600mV, and the preferred condition is 400mV. At this time, all impurity elements such as magnesium and manganese are removed, and before the wastewater enters the bipolar membrane electrodialysis system 3, the hydrogen peroxide and the wastewater are mixed and reacted to remove impurity elements such as magnesium and manganese in the wastewater, and the concentration is limited to within 1ppm.

[0053] Furthermore, in the embodiment of the present application, the wastewater treatment units include but are not limited to two. At this time, the oxidant inlet is set on the pretreatment system 20 located downstream of the two wastewater treatment units, and the first impurity removal of the wastewater is carried out in the first pretreatment system 20. By adding exogenous ammonia water, the impurity removal conditions are controlled at PH5-9, preferably 5.5-6.5. The second impurity removal of the wastewater is carried out in the second pretreatment system 20. By adding exogenous ammonia water, the impurity removal conditions are controlled at PH8-9, preferably PH8.5. After two impurity removals, more impurity ions are removed from the wastewater, the system integration is higher, and the intelligence level is higher.

[0054] Furthermore, in the embodiment of the present application, the pretreatment system 20 of the wastewater treatment unit located at the most upstream is set as an open reaction precipitation system, mainly for heat dissipation; the pretreatment system 20 of the wastewater treatment unit located at the most downstream is set as a closed reaction precipitation system, mainly to prevent ammonia from escaping.

[0055] Further, refer to Figure 2 In the embodiment of the present application, the first membrane treatment system 21 of the wastewater treatment unit located at the most upstream includes a fiber ball filter 200, a first ultrafiltration device 201 and a first reverse osmosis device 202 connected in sequence along the wastewater flow direction. At the same time, the acid chamber outlet of the bipolar membrane electrodialysis system 3 is connected to the outlet of the first ultrafiltration device 201, and the dilute sulfuric acid decomposed in the bipolar membrane electrodialysis system 3 is recycled to the first membrane treatment system 21 through the outlet of the first ultrafiltration device 201. Among them, the fiber ball filter 200 is mainly based on physical filtration, surface capture and charge adsorption mechanisms. The fiber ball filter 200 is filled with a large number of fiber balls to form a three-dimensional network structure. When the liquid passes through the filter, the gaps between the fiber balls can effectively filter out larger solid particles, suspended matter and impurities, making them unable to pass through. At the same time, the surface of the fiber balls can capture smaller particles, and the charges on the fiber balls can adsorb charged impurity particles, thereby achieving efficient water purification. The first ultrafiltration device 201 is a pressurized membrane separation technology. Under a certain pressure, small molecular solutes and solvents pass through a membrane with a specific pore size, while large molecular solutes are retained, thereby achieving separation, purification or concentration of substances. The core of the ultrafiltration device is the ultrafiltration membrane, whose micropores can reach less than 0.01 microns, which can effectively remove particles, colloids, bacteria, heat sources and organic matter in water. The first reverse osmosis device 202 has the same function as the second membrane treatment system 4, so that the wastewater is filtered and purified layer by layer in the upstream treatment link to achieve higher water quality.

[0056] Further, refer to Figure 3 In the embodiment of the present application, the first membrane treatment system 21 of the wastewater treatment unit located at the most downstream includes a multi-media filter 203, a second ultrafiltration device 204 and a second reverse osmosis device 205 which are connected in sequence along the wastewater flow direction. At the same time, the acid chamber outlet of the bipolar membrane electrodialysis system 3 is connected to the outlet of the second ultrafiltration device 204, and the dilute sulfuric acid decomposed in the bipolar membrane electrodialysis system 3 is recycled to the first membrane treatment system 21 through the outlet of the second ultrafiltration device 204.

[0057] Specifically, the difference between the downstream wastewater treatment unit and the upstream wastewater treatment unit lies in the different filter settings; the multi-media filter 203 uses two or more filter media to pass water with higher turbidity through granular or non-granular materials of a specific thickness under a certain pressure, thereby effectively removing suspended impurities and making the water clear.

[0058] Furthermore, the bipolar membrane electrodialysis system 3 also has a by-product discharge outlet, which is connected to a fourth pipe 8, through which the by-products are discharged. The by-products include dilute sulfuric acid, which can be used as a raw material in other production workshops, effectively saving resources and improving resource utilization.

[0059] Furthermore, the iron phosphate production wastewater treatment and recycling production system also includes a third membrane treatment system 9, which is respectively connected to the first membrane treatment system 21 of the wastewater treatment unit located at the most upstream, the first membrane treatment system 21 of the wastewater treatment unit located at the most downstream, and the second membrane treatment system 4. The third membrane treatment system 9 is configured as a reverse osmosis device, and the working principle of the reverse osmosis device is mainly to use pressure to make the filtrate in the suspension pass through the filter layer and the filter cloth, and be discharged through the filter cloth outlet, while the filter residue remains in the filter frame to form a filter cake, thereby achieving the purpose of solid-liquid separation. The fresh water generated by the first membrane treatment system 21 of the wastewater treatment unit at the most upstream, the first membrane treatment system 21 of the wastewater treatment unit at the most downstream, and the second membrane treatment system 4 is connected to the third membrane treatment system 9, and finally pure water is discharged, which meets industrial emission requirements and is beneficial to environmental protection.

[0060] See also Figure 1 According to one or more embodiments of the present application, the iron phosphate production wastewater treatment and circulation production system of the present application includes a bipolar membrane electrodialysis system 3, a second membrane treatment system 4, an evaporation system 5 and at least two wastewater treatment units, and the wastewater treatment unit includes a pretreatment system 20 and a first membrane treatment system 21 connected along the water flow direction. In the wastewater treatment unit, the wastewater is removed and filtered by adding exogenous ammonia water and exogenous sulfuric acid. At the same time, a strong oxidant is introduced into the second wastewater treatment unit to further remove the impurity elements contained in the wastewater and avoid poisoning and damage of the bipolar membrane. Further, a part of the ammonium sulfate is electrolyzed by the bipolar membrane electrodialysis system 3, and the generated dilute ammonia water and dilute sulfuric acid are respectively recycled to the pretreatment system 20 and the first membrane treatment system 21 for recycling, thereby reducing the use of exogenous ammonia water and exogenous sulfuric acid in subsequent wastewater treatment, effectively saving resources, achieving a circular economy, and saving costs.

[0061] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A system for treating and recycling wastewater from iron phosphate production, characterized in that: The invention comprises a wastewater treatment module, a bipolar membrane electrodialysis system (3), a second membrane treatment system (4) and an evaporation system (5) which are sequentially connected along the flow direction of the wastewater; wherein the wastewater treatment module comprises at least one wastewater treatment unit, and the wastewater treatment unit comprises a pretreatment system (20) and a first membrane treatment system (21) which are sequentially distributed along the flow direction of the wastewater; The bipolar membrane electrodialysis system (3) is connected to the pretreatment system (20); The bipolar membrane electrodialysis system (3) is in communication with the first membrane treatment system (21).

2. The iron phosphate production wastewater treatment and recycling production system according to claim 1, characterized in that: The bipolar membrane electrodialysis system (3) has a by-product discharge port.

3. The iron phosphate production wastewater treatment and recycling production system according to claim 1, characterized in that: The wastewater treatment module comprises a plurality of wastewater treatment units connected in sequence. Among the plurality of wastewater treatment units, the pretreatment system (20) of the wastewater treatment unit located most downstream is provided with an oxidant injection port.

4. The iron phosphate production wastewater treatment and recycling production system according to claim 3, characterized in that: Two wastewater treatment units are provided, and the oxidant injection port is provided on the pretreatment system (20) located downstream of the two wastewater treatment units.

5. The iron phosphate production wastewater treatment and recycling production system according to claim 3, characterized in that: The pretreatment system (20) of the wastewater treatment unit located most upstream is configured as an open reaction precipitation system, and the pretreatment system (20) of the wastewater treatment unit located most downstream is configured as a closed reaction precipitation system.

6. The iron phosphate production wastewater treatment and recycling production system according to claim 3, characterized in that: The first membrane treatment system (21) of the wastewater treatment unit located at the most upstream comprises a fiber ball filter (200), a first ultrafiltration device (201) and a first reverse osmosis device (202) which are sequentially connected along the wastewater flow direction, and the bipolar membrane electrodialysis system (3) is connected to the first ultrafiltration device (201).

7. The iron phosphate production wastewater treatment and recycling production system according to claim 3, characterized in that: The first membrane treatment system (21) of the wastewater treatment unit located at the most downstream comprises a multi-media filter (203), a second ultrafiltration device (204) and a second reverse osmosis device (205) which are sequentially connected along the wastewater flow direction, and the bipolar membrane electrodialysis system (3) is connected to the second ultrafiltration device (204).

8. The iron phosphate production wastewater treatment and recycling production system according to claim 1, characterized in that: The second membrane treatment system (4) includes a third reverse osmosis device.

9. The iron phosphate production wastewater treatment and recycling production system according to claim 3, characterized in that: It also includes a third membrane treatment system (9), which is respectively connected to the first membrane treatment system (21) of the wastewater treatment unit located most upstream, the first membrane treatment system (21) of the wastewater treatment unit located most downstream, and the second membrane treatment system (4).

10. The iron phosphate production wastewater treatment and recycling production system according to claim 9, characterized in that: The third membrane treatment system (9) includes a reverse osmosis device.

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