Papermaking wastewater treatment equipment

Abstract

The utility model relates to the technical field of water treatment equipment, in particular to papermaking wastewater treatment equipment which comprises an adjusting tank, a concentration system, a nanofiltration system and a crystallization system. The adjusting tank is provided with a tail water inlet and a water outlet, water to be treated is introduced into the adjusting tank through the tail water inlet, and the water outlet is connected with the concentration system; the concentration system is connected with the nanofiltration system; and the nanofiltration system is connected with the crystallization system. According to the papermaking wastewater treatment equipment provided by the invention, the salt in the papermaking wastewater can be effectively removed through a set of system capable of realizing pretreatment, concentration, nanofiltration salt separation and evaporative crystallization, so that the hardness is reduced, and compared with a traditional papermaking wastewater treatment system, a weak acid cation bed is not used any more, so that the condition that the weak acid cation bed needs to be regenerated is compensated, and the energy consumption is reduced. The complexity of the papermaking wastewater treatment process is simplified, and the generation of regenerated wastewater is also avoided.

Description

Technical Field

[0001] The present application relates to the technical field of water treatment equipment, and in particular to a papermaking wastewater treatment equipment. Background Art

[0002] At present, the papermaking industry is a large water user, and its wastewater discharge is also large, which will have a great impact on the surrounding environment. In order to reduce the processing costs and save water in the papermaking industry, the recycling of its water is an important way to achieve sustainable and high-quality development of the papermaking industry. The recycling and reuse of papermaking wastewater is determined by the characteristics of the wastewater and the quality requirements of the reused water. The closed cycle of papermaking wastewater will cause the harmful substances in the wastewater to gradually accumulate and reach a very high concentration, thereby affecting the normal production of the enterprise. These pollutants include soluble organic matter, salts, secondary adhesives and anionic garbage. Therefore, in order to achieve the recycling and zero discharge of papermaking wastewater, it is necessary to adopt effective treatment technology to treat the wastewater to meet the water quality requirements of the reused water. The existing papermaking wastewater treatment process usually has the following defects: the concentrate from the reverse osmosis contains a certain amount of salt after softening and clarifying treatment, so that the water after softening and clarifying treatment still has a certain hardness. In order to reduce the risk of scaling in the subsequent high-pressure reverse osmosis (STRO) concentration, a weak acid cationic bed ion exchange device is set between the softening and clarification and the high-pressure reverse osmosis to further reduce the hardness of the water. However, after the weak acid cationic bed fails, its regeneration requires a large amount of acid and alkali, the amount of regeneration wastewater is large and the process is complicated. Utility Model Content

[0003] The purpose of the present application is to provide a papermaking wastewater treatment device to solve, to a certain extent, the problem in the prior art that the weak acid cation bed of the existing papermaking wastewater is prone to failure during the treatment process and needs to be regenerated, which not only increases the complexity of the wastewater treatment process, but also produces technical problems in regenerating wastewater.

[0004] The present application provides a papermaking wastewater treatment device, comprising: a regulating tank, a concentration system, a nanofiltration system and a crystallization system, wherein the regulating tank, the concentration system, the nanofiltration system and the crystallization system are arranged in sequence;

[0005] The regulating tank is provided with a tail water inlet and a water outlet, the water to be treated is introduced into the regulating tank through the tail water inlet, the water outlet is connected to the concentration system, and the water to be treated in the regulating tank can flow to the concentration system through the water outlet;

[0006] The concentration system is connected to the nanofiltration system, and the water produced by the concentration system can flow to the nanofiltration system;

[0007] The nanofiltration system is connected to the crystallization system, and the water produced by the nanofiltration system can flow into the crystallization system.

[0008] In the above technical solution, further, the concentration system comprises:

[0009] A membrane bioreactor, wherein the inlet of the membrane bioreactor is connected to the water outlet;

[0010] A first reverse osmosis device, the first reverse osmosis device is connected to the membrane bioreactor; the first reverse osmosis device is provided with a first concentrated water interface;

[0011] A second reverse osmosis device, wherein the inlet of the second reverse osmosis device is connected to the first concentrated water interface.

[0012] In any of the above technical solutions, further, the papermaking wastewater treatment equipment also includes a triple tank, the second reverse osmosis device is provided with a second concentrated water interface, and the inlet of the triple tank is connected to the second concentrated water interface.

[0013] In any of the above technical solutions, further, the papermaking wastewater treatment equipment also includes a tubular membrane device, which is arranged between the triple box and the nanofiltration system, and the tubular membrane device is connected to the triple box and the nanofiltration system respectively.

[0014] In any of the above technical solutions, further, the nanofiltration system comprises:

[0015] a first nanofiltration device, wherein the inlet of the first nanofiltration device is connected to the tubular membrane device, the first nanofiltration device is provided with a first water production interface and a third concentrated water interface, and the third concentrated water interface is connected to the crystallization system;

[0016] The second nanofiltration device, the inlet of the second nanofiltration device is connected to the first water production interface; the second nanofiltration device is provided with a second water production interface and a fourth concentrated water interface, and the fourth concentrated water interface is connected to the first nanofiltration device.

[0017] In any of the above technical solutions, further, the papermaking wastewater treatment equipment also includes:

[0018] a third reverse osmosis device, wherein the inlet of the third reverse osmosis device is connected to the second water production interface;

[0019] The fourth reverse osmosis device, the third reverse osmosis device is further provided with a fifth concentrated water interface, and the inlet of the fourth reverse osmosis device is connected to the fifth concentrated water interface.

[0020] In any of the above technical solutions, further, the crystallization system comprises:

[0021] A first crystallization unit, wherein the inlet of the first crystallization unit is connected to the third concentrated water interface; the first crystallization unit is provided with a first salt analysis outlet;

[0022] The second crystallization unit, the fourth reverse osmosis device is provided with a sixth concentrated water interface, the inlet of the second crystallization unit is connected to the sixth concentrated water interface; the second crystallization unit is provided with a second salt analysis outlet.

[0023] In any of the above technical solutions, further, the papermaking wastewater treatment equipment also includes a drying system, and the first crystallization unit and the second crystallization unit are respectively connected to the drying system.

[0024] In any of the above technical solutions, further, the first reverse osmosis device is also provided with a first recycled water interface;

[0025] The second reverse osmosis device is also provided with a second recycled water interface.

[0026] In any of the above technical solutions, further, the third reverse osmosis device is also provided with a third recycled water interface; the fourth reverse osmosis device is also provided with a fourth recycled water interface.

[0027] Compared with the prior art, the beneficial effects of this application are:

[0028] The papermaking wastewater treatment equipment provided in the present application includes: an equalization tank, a concentration system, a nanofiltration system and a crystallization system, which are arranged in sequence; the equalization tank is provided with a tail water inlet and a water outlet, the water to be treated is introduced into the equalization tank through the tail water inlet, the water outlet is connected to the concentration system, and the water to be treated in the equalization tank can flow to the concentration system through the water outlet; the concentration system is connected to the nanofiltration system, and the water generated by the concentration system can flow to the nanofiltration system; the nanofiltration system is connected to the crystallization system, and the water generated by the nanofiltration system can flow to the crystallization system.

[0029] The papermaking wastewater treatment equipment provided in the present application can effectively remove salt from papermaking wastewater through a system that can realize pretreatment, concentration, nanofiltration salt separation, and evaporation crystallization, thereby reducing hardness. Compared with traditional papermaking wastewater treatment systems, weak acid cationic beds are no longer used, thereby compensating for the need to regenerate weak acid cationic beds, simplifying the complexity of the papermaking wastewater treatment process and avoiding the generation of regenerated wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1This is a schematic diagram of the structure of the papermaking wastewater treatment equipment provided in an embodiment of the present application.

[0032] Reference numerals:

[0033] 1-regulating tank, 101-tail water inlet, 102-outlet, 2-membrane bioreactor, 201-first inlet, 202-first outlet, 3-first reverse osmosis device, 301-second inlet, 302-first concentrated water interface, 303-first recycled water interface, 4-second reverse osmosis device, 401-second concentrated water interface, 402-second recycled water interface, 5-triplet, 501-third inlet, 502-third outlet, 6-tubular membrane device, 601-fourth inlet, 602-fourth outlet, 7-first nanofiltration device, 701-first water production interface, 70 2-third concentrated water interface, 8-second nanofiltration device, 801-second water production interface, 802-fourth concentrated water interface, 9-third reverse osmosis device, 901-fifth concentrated water interface, 902-third recycled water interface, 10-fourth reverse osmosis device, 1001-sixth concentrated water interface, 1002-fourth recycled water interface, 11-first crystallization unit, 1101-first liquid outlet, 1102-first salt analysis outlet, 12-second crystallization unit, 1201-second liquid outlet, 1202-second salt analysis outlet, 13-drying system, 1301-third salt analysis outlet. DETAILED DESCRIPTION

[0034] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0035] The components of the embodiments of the present application generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed, but merely represents the selected embodiments of the present application.

[0036] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0037] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0038] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] Refer to the following Figure 1 The papermaking wastewater treatment equipment according to the embodiment of the present application is described.

[0040] See also Figure 1 As shown, the embodiment of the present application provides a papermaking wastewater treatment equipment, which includes: a regulating tank 1, a concentration system, a nanofiltration system and a crystallization system, wherein the regulating tank 1, the concentration system, the nanofiltration system and the crystallization system are arranged in sequence and sequentially undertake the wastewater treatment task. The regulating tank 1 is provided with a tail water inlet 101 and a water outlet 102, and the tail water inlet 101 serves as the total inlet of the papermaking wastewater treatment equipment. The tail water that has been biochemically treated in the paper mill, that is, the water to be treated, is introduced into the regulating tank 1 through the tail water inlet 101. On the one hand, the regulating tank 1 can play a homogenizing role on the water to be treated. On the other hand, the water to be treated first flows into the regulating tank 1, and the water in the regulating tank 1 flows to the next process, which can improve the overall impact resistance of the papermaking wastewater treatment equipment and improve the stability of the operation of the papermaking wastewater treatment equipment.

[0041] The inlet of the concentration system is connected to the water outlet 102 of the regulating tank 1, and the untreated water in the regulating tank 1 flows into the concentration system for further treatment. The inlet of the nanofiltration system is connected to the concentration system, and the water produced after treatment by the concentration system can flow into the nanofiltration system for further treatment. The inlet of the crystallization system is connected to the nanofiltration system, and the water produced by the nanofiltration system can flow into the crystallization system. The untreated water flowing into the crystallization system is evaporated and crystallized to produce impurities, thereby removing the salt in the incoming water and reducing the hardness of the incoming water.

[0042] It can be seen that the papermaking wastewater treatment equipment provided in the present application can effectively remove salt from papermaking wastewater through a system that can realize pretreatment, concentration, nanofiltration salt separation, and evaporation crystallization, thereby reducing hardness. Compared with traditional papermaking wastewater treatment systems, weak acid cationic beds are no longer used, thereby compensating for the need to regenerate weak acid cationic beds, simplifying the complexity of the papermaking wastewater treatment process and avoiding the generation of regenerated wastewater.

[0043] In one embodiment of the present application, preferably, the concentration system comprises:

[0044] The membrane bioreactor 2, the inlet of the membrane bioreactor 2 is connected to the water outlet 102;

[0045] A first reverse osmosis device 3, the first reverse osmosis device 3 is connected to the membrane bioreactor 2; the first reverse osmosis device 3 is provided with a first concentrated water interface 302;

[0046] The second reverse osmosis device 4 , the inlet of the second reverse osmosis device 4 is connected to the first concentrated water interface 302 .

[0047] In this embodiment, the concentration system includes a membrane bioreactor 2, a first reverse osmosis device 3 and a second reverse osmosis device 4. The membrane bioreactor 2 is provided with a first inlet 201 and a first outlet 202. The first inlet 201 is connected to the outlet 102 of the regulating tank 1. The wastewater flows into the membrane bioreactor 2 through the outlet 102 and the first inlet 201. After biochemical treatment in the membrane bioreactor 2, the organic matter content of the wastewater is effectively reduced.

[0048] It should be noted that the membrane bioreactor 2 (MBR) is a commonly used device in the prior art, which has the functions of biochemical treatment and membrane separation and interception, degrading organic matter in sewage, and nitrifying bacteria nitrifying NH3-N into NO3 - , the organic matter removal rate is above 95%; the ammonia nitrogen removal rate is above 97%; the sludge age can be very long, thus greatly improving the degradation efficiency of difficult-to-degrade organic matter. At the same time, the efficient interception effect of the MBR membrane completely intercepts the microorganisms in the bioreactor, realizes the complete separation of the reactor hydraulic retention time and the sludge age, and the operation control is flexible and stable. It has the advantages of compact structure, beautiful appearance, small footprint, low operating cost, stable and reliable, high degree of automation, and convenient maintenance and operation. It can efficiently separate solids and liquids, and its separation effect is far better than that of traditional sedimentation tanks. The effluent water quality is good, the effluent suspended solids and turbidity are close to zero, and it can be directly reused, realizing the resource utilization of sewage.

[0049] The first reverse osmosis device 3 is provided with a second inlet 301 and a first concentrated water interface 302 . The second inlet 301 is connected to the first outlet 202 . The wastewater treated by the membrane bioreactor 2 flows into the first reverse osmosis device 3 through the first outlet 202 and the second inlet 301 for treatment.

[0050] The inlet of the second reverse osmosis device 4 is connected to the first concentrated water interface 302, and the concentrated water produced by the first reverse osmosis device 3 flows into the second reverse osmosis device 4 through the first concentrated water interface 302 and the inlet of the second reverse osmosis device 4, and is reverse osmosis treated by the second reverse osmosis device 4, thereby achieving two-stage concentration of the wastewater and fully removing impurities, salt and other substances in the wastewater. Preferably, the second reverse osmosis device 4 uses a brackish water reverse osmosis membrane, and the TDS content in the concentrated water of the second reverse osmosis device 4 is 17000-20000 mg / L.

[0051] Preferably, the first reverse osmosis device 3 is also provided with a first recycled water interface 303. After the first reverse osmosis device 3 treats the wastewater, it not only produces concentrated water, but also produces produced water with relatively pure components, close to or almost close to pure water. This part of the produced water can be recycled.

[0052] It should be noted that the first reverse osmosis device 3 and the second reverse osmosis device 4 are both common filtration devices with reverse osmosis membranes in the prior art. Preferably, the first reverse osmosis device 3 uses a brackish water reverse osmosis membrane, and the first reverse osmosis device 3 is set with a first predetermined recovery rate, preferably, the first predetermined recovery rate is designed to be 80%, and the TDS content of the concentrated water of the first reverse osmosis device 3 is 8500-10000 mg / L.

[0053] In one embodiment of the present application, preferably, the papermaking wastewater treatment equipment further includes a triple box 5 , the second reverse osmosis device 4 is provided with a second concentrated water interface 401 , and the inlet of the triple box 5 is connected to the second concentrated water interface 401 .

[0054] In one embodiment of the present application, preferably, the papermaking wastewater treatment equipment also includes a tubular membrane device 6, which is arranged between the triple box 5 and the nanofiltration system, and the tubular membrane device 6 is connected to the triple box 5 and the nanofiltration system respectively.

[0055] In this embodiment, the second reverse osmosis device 4 is provided with a second concentrated water interface 401, the triple box 5 is provided with a third inlet 501 and a third outlet 502, the third inlet 501 is connected to the second concentrated water interface 401, the tubular membrane device 6 is provided with a fourth inlet 601 and a fourth outlet 602, the fourth inlet 601 is connected to the third outlet 502, and the fourth outlet 602 is used to connect to the nanofiltration system.

[0056] When the second reverse osmosis device 4 treats the wastewater flowing into it, it will also produce concentrated water. This concentrated water contains hardness and silicon and other substances that are easy to scale. Therefore, a triple box 5 and a tubular membrane device 6 are set up, and sodium hydroxide and sodium carbonate are added to the triple box 5 respectively, which can precipitate the calcium, magnesium, barium ions, silicon, alkalinity, fluorine and other substances in the concentrated water produced by the second reverse osmosis device 4, and then separate and remove the precipitate after tubular membrane separation, remove the components in the water that are easy to cause membrane scaling, and effectively reduce the hardness of the water. The hardness of the water can be reduced to zero or close to zero, so as to ensure the good operating conditions and high yield of the subsequent nanofiltration, high-pressure reverse osmosis membrane and salt production system. It should be noted that the triple box 5 and the tubular membrane device 6 are both commonly used processes and devices in water treatment equipment.

[0057] Preferably, the second reverse osmosis device 4 is also provided with a second recycled water interface 402. After the second reverse osmosis device 4 treats the wastewater, it will not only produce concentrated water, but also produce water with relatively pure components, close to or almost close to pure water. This part of the produced water can be recycled.

[0058] In one embodiment of the present application, preferably, the nanofiltration system comprises:

[0059] A first nanofiltration device 7, the inlet of which is connected to the tubular membrane device 6, the first nanofiltration device 7 is provided with a first water production interface 701 and a third concentrated water interface 702, and the third concentrated water interface 702 is connected to the crystallization system;

[0060] The second nanofiltration device 8 , the inlet of the second nanofiltration device 8 is connected to the first water production interface 701 ; the second nanofiltration device 8 is provided with a second water production interface 801 and a fourth concentrated water interface 802 , and the fourth concentrated water interface 802 is connected to the first nanofiltration device 7 .

[0061] In this embodiment, the inlet of the first nanofiltration device 7 is connected to the fourth outlet 602 of the tubular membrane device 6, so that water filtered by the tubular membrane device 6 can flow into the first nanofiltration device 7 for further treatment.

[0062] The first nanofiltration device 7 is also provided with a first water production interface 701 and a third concentrated water interface 702. The first water production interface 701 is connected to the inlet of the second nanofiltration device 8, so that the water treated by the first nanofiltration device 7 can flow into the second nanofiltration device 8 for further treatment. The third concentrated water interface 702 is used to connect to the crystallization system. The TDS of the concentrated water produced by the first nanofiltration device 7 is about 80,000 to 100,000 mg / L.

[0063] The second nanofiltration device 8 is also provided with a second water production interface 801 and a fourth concentrated water interface 802. The second water production interface 801 is connected to the inlet of the third reverse osmosis device 9 described below, so that the water treated by the second nanofiltration device 8 can flow into the third reverse osmosis device 9 for further concentration treatment, and the fourth concentrated water interface 802 is connected to the first nanofiltration device 7, and the concentrated water produced by the second nanofiltration device 8 can be sent back to the first nanofiltration device 7 again to mix with the water in the first nanofiltration device 7, so as to be treated again by the first nanofiltration device 7. The TDS of the concentrated water produced by the second nanofiltration device 8 is about 10000-12000 mg / L.

[0064] In one embodiment of the present application, preferably, the papermaking wastewater treatment equipment further comprises:

[0065] A third reverse osmosis device 9, the inlet of the third reverse osmosis device 9 is connected to the second water production interface 801;

[0066] The fourth reverse osmosis device 10 and the third reverse osmosis device 9 are further provided with a fifth concentrated water interface 901 , and the inlet of the fourth reverse osmosis device 10 is connected to the fifth concentrated water interface 901 .

[0067] In this embodiment, the inlet of the third reverse osmosis device 9 is connected to the second water production interface 801, and the concentrated water produced by the second nanofiltration device 8 can enter the third reverse osmosis device 9 for concentration treatment. Preferably, the third reverse osmosis device 9 is also provided with a third recycled water interface 902. The third reverse osmosis device 9 will produce concentrated water and clean water with relatively pure components during operation, and this part of the clean water can be recycled through the third recycled water interface 902. It should be noted that the third reverse osmosis device 9 is specifically a reverse osmosis device with a reverse osmosis membrane commonly used in the prior art.

[0068] The inlet of the fourth reverse osmosis device 10 is connected to the fifth concentrated water interface 901 of the third reverse osmosis device 9, and the concentrated water produced by the third reverse osmosis device 9 can flow into the fourth reverse osmosis device 10 for further concentration. The fourth reverse osmosis device 10 is provided with a sixth concentrated water port, and the sixth concentrated water port is used to connect with the crystallization system. Preferably, the fourth reverse osmosis device 10 is a high-pressure reverse osmosis device commonly used in the prior art, and the working pressure of the high-pressure reverse osmosis membrane contained therein is 2.8 to 4.2 MPa, or higher than 4.2 MPa, and can effectively desalinate water with a higher concentration. Preferably, the recovery rate of the fourth reverse osmosis device 10 is 75%, and the TDS of its concentrated water is about 80,000 to 100,000 mg / L. Preferably, the fourth reverse osmosis device 10 is provided with a fourth recycled water interface 1002.

[0069] In one embodiment of the present application, preferably, the crystallization system comprises:

[0070] A first crystallization unit 11, wherein the inlet of the first crystallization unit 11 is connected to the third concentrated water interface 702;

[0071] The second crystallization unit 12 and the fourth reverse osmosis device 10 are provided with a sixth concentrated water interface 1001 , and the sixth concentrated water interface 1001 is connected to the inlet of the second crystallization unit 12 .

[0072] In one embodiment of the present application, preferably, the papermaking wastewater treatment equipment further includes a drying system 13, and the first crystallization unit 11 and the second crystallization unit 12 are respectively connected to the drying system 13.

[0073] In this embodiment, the inlet of the first crystallization unit 11 is connected to the third concentrated water interface 702 of the first nanofiltration device 7, and the concentrated water released by the first nanofiltration device 7 can flow into the first crystallization unit 11. Preferably, the first crystallization unit 11 can select MVR falling film + forced circulation evaporation crystallization + drying system crystallization to obtain the finished sodium sulfate product. The concentrated water of the first nanofiltration device 7 is evaporated first, so that the concentrated water is in the saturated zone of sodium sulfate and precipitated as sodium sulfate. By controlling the amount of residual liquid evaporated in this section, relatively pure sodium sulfate can be obtained, and the remaining residual liquid is transported to the drying system 13 for treatment. After testing, the finished sodium sulfate product obtained through the above-mentioned salt separation process meets the requirements of Class II first-class products in GB / T 6009-2014.

[0074] The inlet of the second crystallization unit 12 is connected to the sixth concentrated water interface 1001 of the fourth reverse osmosis device 10, and the concentrated water generated by the fourth reverse osmosis device 10 can flow into the second crystallization unit 12 for further treatment. Preferably, the second crystallization unit 12 can select MVR forced circulation evaporation crystallization + drying to produce a sodium chloride dry salt product. The concentrated water of the fourth nanofiltration device is first evaporated, and the concentrated water is treated in the saturated zone of sodium chloride to precipitate sodium chloride. By controlling the amount of residual liquid evaporated in this section, relatively pure sodium chloride can be obtained, and the remaining residual liquid is transported to the drying system 13 for drying treatment.

[0075] After testing, the finished sodium chloride obtained through the above-mentioned salt separation process can meet the requirements of GB / T5462-2015 industrial dry salt first-grade product.

[0076] Furthermore, the first crystallization unit 11 is also provided with a first liquid outlet 1101 and a first salt analysis outlet 1102, and the second crystallization unit 12 is also provided with a second liquid outlet 1201 and a second salt analysis outlet 1202. The first liquid outlet 1101 and the second liquid outlet 1201 are respectively connected to the drying system 13. The first salt analysis outlet 1102 is used to collect sodium sulfate salt, and the second salt analysis outlet 1202 is used to collect sodium chloride salt. The residual liquid in the first crystallization unit 11 and the residual liquid in the second crystallization unit 12 can enter the drying system 13 for drying treatment. The residual liquid will precipitate part of the salt after drying in the drying system 13. This part of the salt is impure salt. The drying system 13 is provided with a third salt analysis outlet 1301 for collecting impure salt. The impure salt can be treated as waste in accordance with relevant requirements.

[0077] Preferably, in this embodiment, the drying system 13 preferably uses an enamel kettle crystallization + mother liquor drying machine system to process the mother liquor to crystallize the impurities.

[0078] It should be noted that the salt in the incoming wastewater is mainly sodium sulfate and sodium chloride. The nanofiltration membrane has a high retention rate for divalent sulfate ions, but basically does not retain monovalent chloride ions. Therefore, the sodium sulfate and sodium chloride in the wastewater can be separated by using a nanofiltration membrane treatment device.

[0079] In this embodiment, preferably, the first nanofiltration device 7 is provided with a second predetermined recovery rate, and the second predetermined recovery rate is preferably designed to be 80%. Since the retention rate of the nanofiltration membrane for chloride ions is limited, the salt in the concentrated water produced by the first nanofiltration device 7 is mainly sodium sulfate. Preferably, the second nanofiltration device 8 is provided with a third predetermined recovery rate, and the third predetermined recovery rate is preferably designed to be 75%. The salt in the concentrated water produced by the second nanofiltration device 8 is mainly sodium sulfate, and the produced water of the first nanofiltration device 7 will enter the second nanofiltration device 8 for further separation and concentration, and the concentrated water produced by the second nanofiltration device 8 will flow into the first nanofiltration device 7 and mix with the inlet water of the first nanofiltration device 7, thereby helping to improve the recovery rate of the sodium sulfate salt of the first crystallization unit 11 after the concentrated water produced by the first nanofiltration device 7 flows to the first crystallization unit 11. Therefore, the salt precipitated from the first crystallization unit 11 is mainly sodium sulfate salt, and the first crystallization unit 11 can also be used as a sodium sulfate crystallization unit for precipitating sodium sulfate salt.

[0080] Furthermore, after the first nanofiltration device 7 and the second nanofiltration device 8 separate the sodium sulfate salt and the sodium chloride salt, the water produced by the second nanofiltration device 8 is processed by the third reverse osmosis device 9 and the fourth reverse osmosis device 10, and the salt in the concentrated water of the fourth reverse osmosis device 10 is mainly sodium chloride. The fourth reverse osmosis device 10 is evaporated to precipitate the sodium chloride salt. By controlling the amount of residual liquid evaporated in this section, relatively pure sodium chloride can be obtained. The remaining residual liquid is sent to the drying system 13 for drying treatment to obtain miscellaneous salts with general recycling value.

[0081] To sum up, the papermaking wastewater treatment equipment provided by the present application, the papermaking wastewater treatment equipment provided by the present application, through a system that can realize pretreatment, concentration, nanofiltration salt separation, and evaporation crystallization, can effectively remove salt from papermaking wastewater, thereby reducing hardness. Compared with traditional papermaking wastewater treatment systems, weak acid cationic beds are no longer used, thereby compensating for the need to regenerate weak acid cationic beds, simplifying the complexity of the papermaking wastewater treatment process, and avoiding the generation of regenerated wastewater.

[0082] In addition, the papermaking wastewater treatment equipment provided in this application can also realize the separation and recycling of two usable salts, as well as the recycling of usable water, thereby reducing the discharge of waste and the subsequent disposal procedures and costs of secondary wastewater and salt, thereby reducing the operating costs for recycled water reuse and zero-emission treatment in the papermaking industry.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A papermaking wastewater treatment equipment, characterized in that: include: A regulating tank, a concentration system, a nanofiltration system and a crystallization system, wherein the regulating tank, the concentration system, the nanofiltration system and the crystallization system are arranged in sequence; The regulating tank is provided with a tail water inlet and a water outlet, the water to be treated is introduced into the regulating tank through the tail water inlet, the water outlet is connected to the concentration system, and the water to be treated in the regulating tank can flow to the concentration system through the water outlet; The concentration system is connected to the nanofiltration system, and the water produced by the concentration system can flow to the nanofiltration system; The nanofiltration system is connected to the crystallization system, and the water produced by the nanofiltration system can flow into the crystallization system.

2. The papermaking wastewater treatment equipment according to claim 1, characterized in that: The concentration system comprises: A membrane bioreactor, wherein the inlet of the membrane bioreactor is connected to the water outlet; A first reverse osmosis device, the first reverse osmosis device is connected to the membrane bioreactor; the first reverse osmosis device is provided with a first concentrated water interface; A second reverse osmosis device, wherein the inlet of the second reverse osmosis device is connected to the first concentrated water interface.

3. The papermaking wastewater treatment equipment according to claim 2, characterized in that: The papermaking wastewater treatment equipment further comprises a triple box, the second reverse osmosis device is provided with a second concentrated water interface, and the inlet of the triple box is connected to the second concentrated water interface.

4. The papermaking wastewater treatment equipment according to claim 3, characterized in that: The papermaking wastewater treatment equipment also includes a tubular membrane device, which is arranged between the triple box and the nanofiltration system, and the tubular membrane device is connected to the triple box and the nanofiltration system respectively.

5. The papermaking wastewater treatment equipment according to claim 4, characterized in that: The nanofiltration system comprises: a first nanofiltration device, wherein the inlet of the first nanofiltration device is connected to the tubular membrane device, the first nanofiltration device is provided with a first water production interface and a third concentrated water interface, and the third concentrated water interface is connected to the crystallization system; The second nanofiltration device, the inlet of the second nanofiltration device is connected to the first water production interface; the second nanofiltration device is provided with a second water production interface and a fourth concentrated water interface, and the fourth concentrated water interface is connected to the first nanofiltration device.

6. The papermaking wastewater treatment equipment according to claim 5, characterized in that: The papermaking wastewater treatment equipment also includes: a third reverse osmosis device, wherein the inlet of the third reverse osmosis device is connected to the second water production interface; The fourth reverse osmosis device, the third reverse osmosis device is further provided with a fifth concentrated water interface, and the inlet of the fourth reverse osmosis device is connected to the fifth concentrated water interface.

7. The papermaking wastewater treatment equipment according to claim 6, characterized in that: The crystallization system comprises: A first crystallization unit, wherein the inlet of the first crystallization unit is connected to the third concentrated water interface; the first crystallization unit is provided with a first salt analysis outlet; The second crystallization unit, the fourth reverse osmosis device is provided with a sixth concentrated water interface, the inlet of the second crystallization unit is connected to the sixth concentrated water interface; the second crystallization unit is provided with a second salt analysis outlet.

8. The papermaking wastewater treatment equipment according to claim 7, characterized in that: The papermaking wastewater treatment equipment also includes a drying system, and the first crystallization unit and the second crystallization unit are respectively connected to the drying system.

9. The papermaking wastewater treatment equipment according to claim 2, characterized in that: The first reverse osmosis device is also provided with a first recycled water interface; The second reverse osmosis device is also provided with a second recycled water interface.

10. The papermaking wastewater treatment equipment according to claim 6, characterized in that: The third reverse osmosis device is also provided with a third recycled water interface; the fourth reverse osmosis device is also provided with a fourth recycled water interface.

Images