Wastewater desalination treatment system and treatment process

Abstract

The application provides a wastewater desalination treatment system and treatment process. The wastewater desalination treatment system comprises: a nanofiltration interception module, the nanofiltration interception module comprising a first nanofiltration device, a second nanofiltration device and a third nanofiltration device; a microbial treatment module, the microbial treatment module comprising a sulfate-reducing bacteria reaction device and a Thiobacillus denitrificans reaction device; and an electrodialysis-reverse osmosis module, the electrodialysis-reverse osmosis module comprising an electrodialysis device and a first reverse osmosis device. The wastewater desalination treatment system and treatment process can separate monovalent salt wastewater and divalent salt wastewater from high-salt wastewater through the nanofiltration interception module, the monovalent salt wastewater can be treated by the electrodialysis-reverse osmosis module to obtain recyclable industrial salt sodium chloride, and the divalent salt wastewater can be treated by the microbial treatment module to obtain recyclable elemental sulfur. The sulfate and chloride ions in the high-salt wastewater can be respectively converted into elemental sulfur and sodium chloride for recycling, and the wastewater treatment efficiency is high and the energy consumption is low.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a wastewater desalination treatment system and treatment process. Background Art

[0002] High-salinity wastewater includes wastewater generated from recycled desalination, deep-treatment concentrate, desalinated water concentrate, and other high-salinity processes, such as wet desulfurization wastewater from sintering and coal-fired power plants, coal chemical wastewater, landfill leachate, and industrial wastewater from the petrochemical refining industry. Depending on its source, high-salinity wastewater contains inorganic ions with salinity levels ranging from 3,000 to 50,000 mg / L, or even higher, and a certain amount of difficult-to-biodegrade COD. The generation of high-salinity wastewater is a long-standing issue, and its production is increasing, especially with the increasing application of desalination technology in raw water treatment and wastewater reuse. Furthermore, the continuous tightening of environmental regulations has placed higher demands on the treatment and disposal of high-salinity wastewater.

[0003] In the existing technology, high-salt wastewater is usually treated by thermal salt separation and crystallization processes, salt and salt co-production salt separation and crystallization processes, low-temperature crystallization processes, or membrane salt separation and crystallization processes (including nanofiltration salt separation processes and monovalent selective ion exchange membrane electrodialysis salt separation processes). However, the separation targets of the salt separation and crystallization process in high-salt wastewater are mainly sodium chloride and sodium sulfate. The existing high-salt wastewater treatment methods have the following defects: the process system is complex and difficult to control, with high downtime and accident rates; the purity of the finished salt is poor, the market for mirabilite is oversaturated, and sales are seriously sluggish; the overall energy consumption is high, and the cost of treating a ton of water is high.

[0004] Therefore, there is an urgent need for a wastewater desalination treatment system and treatment process that can solve the above problems. Summary of the Invention

[0005] On the one hand, the present invention provides a wastewater desalination treatment system, which can react sulfate and chloride ions in high-salt wastewater into elemental sulfur and sodium chloride respectively for recovery and treatment through a nanofiltration interception module, a microbial treatment module and an electrodialysis-reverse osmosis module, and has high wastewater treatment efficiency and low energy consumption.

[0006] Another aspect of the present invention provides a wastewater desalination process.

[0007] The present invention provides a wastewater desalination treatment system, comprising:

[0008] A nanofiltration retention module, the nanofiltration retention module comprising a first nanofiltration device, a second nanofiltration device and a third nanofiltration device, the water production end of the first nanofiltration device being in communication with the water inlet end of the second nanofiltration device, the concentrated liquid outlet end of the first nanofiltration device being in communication with the water inlet end of the third nanofiltration device, the concentrated liquid outlet end of the second nanofiltration device being in communication with the water inlet end of the third nanofiltration device, and the water production end of the third nanofiltration device being in communication with the water inlet end of the second nanofiltration device;

[0009] a microbial treatment module, the microbial treatment module comprising a sulfate-reducing bacteria reaction device and a denitrifying thiobacillus reaction device, the water inlet end of the sulfate-reducing bacteria reaction device being in communication with the concentrated liquid outlet end of the third nanofiltration device, the water outlet end of the sulfate-reducing bacteria reaction device being in communication with the water inlet end of the denitrifying thiobacillus reaction device, the sulfate-reducing bacteria reaction device being adapted to utilize sulfate-reducing bacteria to react sulfate radicals in the wastewater into divalent sulfide ions, and the denitrifying thiobacillus reaction device being adapted to utilize denitrifying thiobacillus to react divalent sulfide ions in the wastewater into elemental sulfur;

[0010] An electrodialysis-reverse osmosis module includes an electrodialysis device and a first reverse osmosis device, the water production end of the second nanofiltration device is connected to the water inlet end of the electrodialysis device, and the electrodialysis device and the first reverse osmosis device are connected to each other.

[0011] The wastewater desalination treatment system provided by the present invention further includes a pretreatment module, wherein the pretreatment module includes an electro-Fenton-air flotation combined treatment module and a tubular membrane filtration device connected in sequence;

[0012] The electro-Fenton-air flotation combined treatment module includes an electrochemical precipitation device, an air flotation and dissolution device, and an air source;

[0013] The electrochemical precipitation device includes an electrochemical reaction cell, wherein a precipitation module, a water inlet module, an electrochemical module, and a produced water collection module are sequentially arranged from bottom to top in the electrochemical reaction cell; the electrochemical module includes a plurality of electrochemical units spaced apart in a vertical direction, each of the electrochemical units includes an anode and a cathode aeration tube, and anode fillers are filled between adjacent electrochemical units;

[0014] The flotation and air dissolution device includes an outer shell, an ejector, a water inlet pipe, an air inlet pipe, and a water supply pipe. The outlet end of the ejector is in communication with the inner cavity of the outer shell, the water inlet pipe and the air inlet pipe are in communication with the ejector respectively, and the inlet end of the water supply pipe is in communication with the inner cavity of the outer shell; the produced water collection module is in communication with the water inlet pipe, the outlet end of the water supply pipe is in communication with the cathode aeration pipe, and the air source is in communication with the air inlet pipe.

[0015] The tubular membrane filtration device is provided with a water inlet and a water outlet, and the water outlet of the tubular membrane filtration device is communicated with the water inlet of the first nanofiltration device.

[0016] According to the wastewater desalination treatment system provided by the present invention, a resin adsorption reaction device is provided between the tubular membrane filtration device and the first nanofiltration device, and the resin adsorption reaction device is suitable for removing at least one of residual hardness, heavy metal ions and residual COD in the wastewater.

[0017] According to the wastewater desalination treatment system provided by the present invention, a second reverse osmosis device is provided between the resin adsorption reaction device and the first nanofiltration device, and the second reverse osmosis device is suitable for concentrating the wastewater.

[0018] The wastewater desalination treatment system provided by the present invention further includes an MVR module, wherein the MVR module includes an inlet water preheater, a buffer device, a falling film evaporator, a vapor-liquid separator, a steam compressor and a heat pump unit;

[0019] The water inlet preheater, the buffer device, the falling film evaporator and the vapor-liquid separator are connected in sequence, one side of the steam compressor is connected to the vapor phase outlet of the vapor-liquid separator, the other side of the steam compressor is connected to the steam inlet of the falling film evaporator, the condensed water outlet of the falling film evaporator is connected to the water inlet preheater, and the heat pump unit is suitable for providing a heat-conducting medium to the buffer device for heating.

[0020] The wastewater desalination treatment system provided by the present invention further includes an evaporation crystallization module, wherein the evaporation crystallization module includes a thickener, a centrifugal filter, an evaporation crystallization unit, a centrifugal dehydrator and a dryer;

[0021] The water inlet end of the thickener is communicated with the liquid phase outlet of the vapor-liquid separator, and the outlet end of the thickener is communicated with the water inlet end of the centrifugal filter.

[0022] The wastewater desalination treatment system provided by the present invention further includes a bipolar membrane electrodialysis module, and the bipolar membrane electrodialysis module is connected to the water outlet end of the electrodialysis device.

[0023] The wastewater desalination treatment system provided by the present invention also includes a magnetoelectric composite scale inhibition and sterilization device, which includes a reactor, an electric field generating module and a magnetic field generating module. The reactor is provided with a water inlet and a drain outlet. The electric field generating module includes an ion generator, which is arranged in the inner cavity of the reactor. The ion generator is suitable for generating an electrostatic field between the ion generator and the inner wall of the reactor. The magnetic field generating module includes a first magnetic field generating unit and a second magnetic field generating unit respectively arranged on both sides of the reactor. The first magnetic field generating unit and the second magnetic field generating unit are suitable for generating an alternating magnetic field in the inner cavity of the reactor.

[0024] The drain outlet of the magneto-electric composite scale inhibition and sterilization device is communicated with the water inlet end of the first nanofiltration device.

[0025] The present invention further provides a wastewater desalination treatment process based on the wastewater desalination treatment system as described in any one of the above items, comprising:

[0026] Passing the wastewater into the nanofiltration interception module, intercepting and separating sulfate and chloride ions in the wastewater by the first nanofiltration device, the second nanofiltration device, and the third nanofiltration device to obtain monovalent salt wastewater and divalent salt wastewater, respectively;

[0027] Passing the monovalent salt wastewater into the electrodialysis-reverse osmosis module, concentrating the monovalent salt wastewater through the electrodialysis device and the first reverse osmosis device, and passing the concentrated monovalent salt wastewater into the MVR module for treatment to obtain sodium chloride;

[0028] The divalent salt wastewater is passed into the microbial treatment module, and sulfate radicals in the divalent salt wastewater are reacted into elemental sulfur by the sulfate-reducing bacteria in the sulfate-reducing bacteria reaction device and the denitrifying thiobacillus in the denitrifying thiobacillus reaction device in sequence.

[0029] The wastewater desalination treatment process provided by the present invention further includes:

[0030] Before the wastewater is passed into the nanofiltration interception module, the wastewater is passed into the pretreatment module, and some hardness, heavy metal ions, F - , total silicon and COD to obtain wastewater A;

[0031] Passing the wastewater A into a resin adsorption reaction device to remove residual hardness, heavy metal ions and residual COD in the wastewater A to obtain wastewater B;

[0032] Detecting the concentration of sulfate and chloride ions in the wastewater B, and in the case that the concentration of sulfate and chloride ions in the wastewater B is lower than a set value, the wastewater is introduced into a second reverse osmosis device for concentration treatment.

[0033] The wastewater desalination treatment process provided by the application further comprises:

[0034] The wastewater at the outlet of the electrodialysis device is introduced into a bipolar membrane electrodialysis module to recover hydrogen chloride and sodium hydroxide in the wastewater.

[0035] The wastewater desalination treatment system and process provided by the application can react sulfate and chloride ions in the high-salinity wastewater into elemental sulfur and sodium chloride respectively for recycling, and has high wastewater treatment efficiency and low energy consumption.

[0036] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0038] Figure 1 is a schematic diagram of the wastewater desalination treatment system provided by the embodiments of the application;

[0039] Figure 2 is a schematic diagram of the nanofiltration retention module in the wastewater desalination treatment system provided by the embodiments of the application;

[0040] Figure 3 is a schematic diagram of the microbial treatment module in the wastewater desalination treatment system provided by the embodiments of the application;

[0041] Figure 4 is a schematic diagram of the electrodialysis-reverse osmosis module in the wastewater desalination treatment system provided by the embodiments of the application;

[0042] Figure 5 is a schematic diagram of a pretreatment module in a wastewater desalination treatment system provided by an embodiment of the present application;

[0043] Figure 6 is a schematic diagram of an electro-Fenton-air flotation combined treatment module in a wastewater desalination treatment system provided by an embodiment of the present application;

[0044] Figure 7 is a schematic diagram of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0045] Figure 8 is a schematic diagram of a dissolved air flotation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0046] Figure 9 is a schematic diagram of an anode of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0047] Figure 10 is a schematic diagram of a cathode aeration pipe of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0048] Figure 11 is a schematic diagram of a cross section of an aeration branch pipe of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0049] Figure 12 is a schematic diagram of a power supply connection of an electrochemical module of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0050] Figure 13 is a schematic diagram of a water inlet module of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0051] Figure 14 is a schematic diagram of a water production collection module of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0052] Figure 15 is a schematic diagram of a water collection assembly of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0053] Figure 16 is a schematic diagram of a slag scraping module of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application;

[0054] Figure 17 is a schematic diagram of a slag scraping module of an electrochemical precipitation device in a wastewater desalination treatment system provided by an embodiment of the present application; Figure 18 is a schematic diagram of an MVR module in a wastewater desalination treatment system provided by an embodiment of the present application;

[0055] Figure 19 Schematic diagram of a falling film evaporator of an MVR module in a wastewater desalination treatment system provided by an embodiment of the present invention;

[0056] Figure 20 It is a schematic diagram of a falling film evaporator of an MVR module in a wastewater desalination treatment system provided by an embodiment of the present invention.

[0057] Figure 21 is a schematic diagram of a bipolar membrane electrodialysis module in a wastewater desalination treatment system provided by an embodiment of the present invention;

[0058] Figure 22 This is one of the schematic diagrams of a magnetoelectric composite scale inhibition and sterilization device in a wastewater desalination treatment system provided by an embodiment of the present invention;

[0059] Figure 23 This is a second schematic diagram of a magnetoelectric composite scale inhibition and sterilization device in a wastewater desalination treatment system provided by an embodiment of the present invention;

[0060] Figure 24 Schematic diagram of an electric field generating module of a magnetoelectric composite scale inhibition and sterilization device in a wastewater desalination treatment system provided by an embodiment of the present invention;

[0061] Figure 25 This is a partial schematic diagram of a magnetic field generating unit of a magnetoelectric composite scale inhibition and sterilization device in a wastewater desalination treatment system provided by an embodiment of the present invention;

[0062] Figure 26 Schematic diagram of the combined effect of electric and magnetic fields in a reactor of a magnetoelectric composite scale inhibition and sterilization device in a wastewater desalination treatment system provided by an embodiment of the present invention;

[0063] Figure 27 is a process flow chart of a wastewater desalination process provided by an embodiment of the present invention;

[0064] Figure 28 It is a schematic diagram of the average retention rate of the nanofiltration retention module in the wastewater desalination treatment process provided by an embodiment of the present invention.

[0065] Reference numerals:

[0066] 1. Electro-Fenton-air floatation combined treatment module; 101, electrochemical precipitation device; 102, air floatation dissolving device; 103, electrochemical reaction tank; 104, anode; 105, cathode aeration pipe; 1051, aeration main pipe; 1052, aeration branch pipe; 1052a, inner aeration pipe; 1052b, protective sleeve; 1052c, reduction reaction layer; 106, outer shell; 107, water jet device; 108, water inlet pipe; 109, air inlet pipe; 110, water supply pipe; 111, support filter plate; 112, sludge discharge port; 113, precipitation area; 114, maintenance opening; 115, anode terminal; 116, cathode terminal; 117, water distribution main pipe; 118, water distribution branch pipe; 119, water collection main pipe; 120, water collection branch pipe; 121, water drainage tank; 122, water level regulator; 1221, adjusting sleeve; 1222, hand wheel; 123, scraper; 124, slag discharge tank; 125, slag discharge port; 126, driving motor; 127, pressure detection device; 128, speed reducer; 129, mounting plate; 130, fixing seat; 131, circulating pump; 132, expansion pipe; 133, spray pipe; 134, first partition plate; 135, second partition plate; 136, third partition plate; 137, filter screen;

[0067] 2. Magneto-electric composite scale inhibition and sterilization device; 201, reactor; 202, water inlet; 203, water outlet; 204, ion generator; 205, guide rod; 205a, metal pull bolt; 205b, metal rod; 206, wire; 207, limiting block; 208, fastening nut; 209, compression nut; 210, insulating sleeve; 211, insulating cover plate; 211a, insulating cover plate body; 211b, insulating cover plate flange; 212, first flange plate; 213, coil; 214, metal sleeve; 215, metal inner core; 216, second flange plate; 217, third flange plate; 218, fourth flange plate; 219, fifth flange plate;

[0068] 3. Nanofiltration rejection module; 301, first nanofiltration device; 302, second nanofiltration device; 303, third nanofiltration device;

[0069] 4. Microbial treatment module; 401, sulfate-reducing bacteria reaction device; 402, denitrifying thiobacillus reaction device;

[0070] 5. Electrodialysis-reverse osmosis module; 501, electrodialysis device; 502, reverse osmosis device;

[0071] 6. MVR module; 601, water inlet preheater; 602, buffer device; 603, falling film evaporator; 604, vapor-liquid separator; 605, steam compressor; 606, heat pump unit;

[0072] 7. Evaporation crystallization module; 701. Thickener; 702. Centrifugal filter; 703. Evaporation crystallization unit; 704. Centrifugal dehydrator; 705. Dryer;

[0073] 8. Tubular membrane filtration device; 9. Sludge thickening tank; 10. Sludge dewatering device; 11. Resin adsorption reaction device; 12. Second reverse osmosis device; 13. Bipolar membrane electrodialysis module. DETAILED DESCRIPTION

[0074] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0075] In the existing technology, high-salt wastewater is usually treated by thermal salt separation crystallization process, salt and nitrate co-production salt separation crystallization process, low-temperature crystallization process or membrane salt separation crystallization process (including nanofiltration salt separation process and monovalent selective ion exchange membrane electrodialysis salt separation process).

[0076] Among them, the thermal salt separation crystallization process includes direct evaporation crystallization process, salt and nitre co-production salt separation crystallization process and low-temperature crystallization process.

[0077] Direct evaporation crystallization: When high-salt wastewater contains a predominant salt component, direct evaporation crystallization can be used. The predominant salt component is concentrated and reduced in an evaporator to near saturation, then enters a pure salt crystallizer to extract the majority of the sodium chloride or sodium sulfate. The concentration ratio in the pure salt crystallizer is controlled to near saturation of the less predominant salt component. The mother liquor discharged from the pure salt crystallizer enters a mixed salt crystallizer to extract the contaminated salt. This process is simple and easy to control, but the inorganic salt recovery rate is low, and the contaminated salt can easily become hazardous waste.

[0078] Salt-nitrate co-production and salt separation crystallization process: When the dominant salt component in the wastewater is not prominent, a stepwise crystallization of sodium sulfate and sodium chloride can be used, with sodium sulfate crystallized at a higher temperature and sodium chloride crystallized at a lower temperature. Between 50 and 120°C, the solubility of sodium chloride increases with increasing temperature, while the solubility of sodium sulfate decreases. Therefore, the salt-nitrate co-production and salt separation crystallization process uses evaporative crystallization (the first crystallizer) at a lower temperature to produce sodium chloride, while simultaneously concentrating the sodium sulfate. When the sodium sulfate nears saturation, the mother liquor from crystallizer I is fed to the second crystallizer, which operates at a higher temperature. Sodium sulfate precipitates due to its decreased solubility, while sodium chloride becomes unsaturated due to its increased solubility. Evaporation of water causes further precipitation of sodium sulfate, gradually approaching the sodium chloride concentration at that temperature. A portion of the mother liquor is returned to the first crystallizer for sodium chloride crystallization, and this cycle is repeated to separate sodium chloride and sodium sulfate. The salt-nitrate co-production and salt separation crystallization process originated in the salt chemical industry and has been widely used in industry, making the process relatively mature overall. However, when applied to the wastewater industry, the impact of impurities such as organic matter needs to be considered. Furthermore, since this process requires precise control of the saturation point of sodium sulfate and sodium chloride at a specific temperature, it is difficult to control and has poor resistance to fluctuations in the composition of the antigenic water.

[0079] Low-temperature crystallization process: Sodium sulfate precipitates as sodium sulfate decahydrate in the low-temperature range. Its solubility decreases significantly with decreasing temperature within the range of 0-30°C. However, the solubility of sodium chloride in the low-temperature range has the same temperature dependence as that in the high-temperature range. By concentrating high-salt wastewater containing a mixture of sodium sulfate and sodium chloride to a certain concentration at a high temperature and then rapidly cooling it, a large amount of sodium sulfate decahydrate (glauber's salt) solid can be crystallized. This is the basic principle of salt separation achieved through low-temperature crystallization. The low-temperature crystallization process only produces solid sodium sulfate; to obtain sodium chloride, it must be combined with a high-temperature crystallization process. Glauber's salt obtained through low-temperature crystallization has a lower market price, and a hot melt evaporation crystallization unit is usually required to obtain anhydrous sodium sulfate (sodium sulfate). The disadvantage of this process is the large temperature range and the higher energy consumption during the cooling and heating processes.

[0080] Membrane salt separation and crystallization processes include nanofiltration salt separation process and monovalent selective ion exchange membrane electrodialysis salt separation process (referred to as electrodialysis salt separation process), which are usually used in conjunction with thermal crystallization process to achieve the purpose of salt separation and crystallization.

[0081] The nanofiltration salt separation process utilizes the selective retention characteristics of nanofiltration membranes for divalent salts to achieve the separation of monovalent salt sodium chloride and divalent salt sodium sulfate in the liquid phase. Sodium chloride mainly enters the nanofiltration permeate, while sodium sulfate is concentrated in the nanofiltration concentrate. By crystallizing the nanofiltration permeate and concentrate separately, the sodium chloride and sodium sulfate crystallized salts are ultimately recovered. Nanofiltration is commonly coupled with low-temperature crystallization to achieve the separation and crystallization of sodium sulfate and sodium chloride in a salt separation crystallization process. The low-temperature crystallization process sets up a circulation loop for the supernatant to reflux into the nanofiltration system, effectively reducing the impact of organic matter on the color of the crystallized salt while ensuring the purity and recovery rate of sodium sulfate and sodium chloride. The improvement in the overall recovery rate directly reduces the production and disposal costs of miscellaneous salt solid waste. The operating temperature difference between the nanofiltration system and the low-temperature crystallizer is small, which has better economic efficiency.

[0082] The electrodialysis salt separation process uses an electrodialysis system comprised of a monovalent selective anion exchange membrane and a conventional cation exchange membrane to separate sodium chloride and sodium sulfate. Under the influence of a DC electric field, chloride ions and sodium ions in the raw water pass through the monovalent selective anion exchange membrane and cation exchange membrane, respectively, into the concentrate chamber, producing a sodium chloride concentrate. The reduced sodium chloride concentration in the dilute chamber increases the relative sodium sulfate content, thus separating the two. The salt separation effect is similar to that of the nanofiltration process, resulting in a sodium chloride brine and a mixed brine of sodium chloride and sodium sulfate. The difference is that the sodium chloride brine produced by the electrodialysis process is simultaneously concentrated, meaning that the sodium chloride content in the concentrated brine is higher than that in the raw water. Conversely, the sodium sulfate content in the mixed brine exiting the dilute chamber is essentially the same as in the raw water, unlike the nanofiltration process, which concentrates the sodium sulfate. Due to cost constraints, electrodialysis salt separation technology has not yet been widely adopted for high-salinity wastewater.

[0083] In addition, the desulfurization wastewater also has a flue evaporation process, which produces miscellaneous salts that easily form solid waste or hazardous waste, corrode the main equipment, affect the main process efficiency, reduce the quality of coal ash, and affect resource recycling. These factors limit its promotion and application.

[0084] From the above, it can be seen that the wastewater desalination treatment technology in the prior art has the following defects:

[0085] Membrane salt separation, concentration and reduction unit:

[0086] Membrane product design issues require high membrane drive pressure and high power consumption.

[0087] The membrane element design is unreasonable, the pretreatment is insufficient, the membrane is seriously fouled and blocked, the designed service life cannot be achieved, and cleaning and replacement are frequent.

[0088] The salt separation design is unreasonable, the separation of sodium chloride and sodium sulfate is not complete, the output of impurity salt is high, the final salt does not meet the national standard requirements, and solid waste / hazardous waste is generated.

[0089] The membrane combination and structural design do not adequately consider the salt components of the wastewater, the concentration and reduction are not thorough, and the final evaporation crystallization unit processes a large amount of water, wasting resources.

[0090] Utilization of super-concentrated brine resources:

[0091] The coordinated processing methods of production processes such as flue evaporation, waste residue utilization, and wet coking affect normal production, increase process energy consumption, and generate hazardous waste.

[0092] Evaporation crystallization process is currently the main form of achieving zero emissions. Evaporation crystallization mainly uses thermal methods to evaporate water and saturate salt precipitation, including traditional processes such as multi-effect evaporation (MED), steam mechanical recompression (MVR), and thermal vapor compression forced circulation (TVC). Generally, the energy consumption for evaporating a ton of water is 333KWh, which is very high.

[0093] Therefore, the present invention provides a wastewater desalination treatment system and a wastewater desalination treatment process to solve the above problems.

[0094] The following combination Figure 1-Figure 28 The wastewater desalination treatment system and wastewater desalination treatment process provided by the present invention are described.

[0095] like Figure 1 As shown, the present invention provides a wastewater desalination treatment system, which includes a nanofiltration interception module 3, a microbial treatment module 4 and an electrodialysis-reverse osmosis module 5.

[0096] like Figure 2 As shown, the nanofiltration retention module 3 includes a first nanofiltration device 301, a second nanofiltration device 302 and a third nanofiltration device 303. The water production end of the first nanofiltration device 301 is connected to the water inlet end of the second nanofiltration device 302, the concentrated liquid outlet end of the first nanofiltration device 301 is connected to the water inlet end of the third nanofiltration device 303, the concentrated liquid outlet end of the second nanofiltration device 302 is connected to the water inlet end of the third nanofiltration device 303, and the water production end of the third nanofiltration device 303 is connected to the water inlet end of the second nanofiltration device 302.

[0097] like Figure 3As shown, the microbial treatment module 4 includes a sulfate-reducing bacteria reaction device 401 and a denitrifying thiobacillus reaction device 402. The water inlet of the sulfate-reducing bacteria reaction device 401 is connected to the concentrated liquid outlet of the third nanofiltration device 303, and the water outlet of the sulfate-reducing bacteria reaction device 401 is connected to the water inlet of the denitrifying thiobacillus reaction device 402. The sulfate-reducing bacteria reaction device 401 is suitable for using sulfate-reducing bacteria to react sulfate radicals in the wastewater into divalent sulfide ions, and the denitrifying thiobacillus reaction device 402 is suitable for using denitrifying thiobacillus to react divalent sulfide ions in the wastewater into elemental sulfur. Specifically, the sulfate-reducing bacteria reaction device 401 and the denitrifying thiobacillus reaction device 402 have the same structure, both of which are packed circulating fluidized reactors filled with K3 type fluidized fillers. The wastewater enters the water distribution area at the bottom of the tank body through the water inlet pipe at the bottom, and enters the filler area through the Rafael nozzle on the water distribution plate. Due to the spraying action of the nozzle, a fluidized state is formed in the filler area. A screen is provided on the top of the filler to prevent the filler from being lost. The water treated by the filler microorganisms is discharged from the water production pipe. The overall process sets a certain reflux rate, and a reflux pump is designed. An automatic exhaust valve is provided on the top of the tank body. Since the tank body undergoes anaerobic reaction, a certain amount of gas will be generated, which is discharged by the automatic exhaust valve. The tank body is provided with an inspection manhole and a sewage pipe is provided at the bottom of the tank. The tank body treatment load rate r≤9Kg / m 3 d.

[0098] According to the water volume and quality, the water distribution plate at the bottom of the bed is made and the Rafale nozzle is installed. The Rafale nozzle ensures that the inlet pressure is not less than 1.5Kg / cm 2 The K3 fluidized packing in the tank is conducive to bacterial growth, has a large specific surface area, and a filling rate between 50-70%.

[0099] like Figure 4 As shown, the electrodialysis-reverse osmosis module 5 includes an electrodialysis device 501 and a first reverse osmosis device 502, the water production end of the second nanofiltration device 302 is connected to the water inlet end of the electrodialysis device 501, and the electrodialysis device 501 and the first reverse osmosis device 502 are connected to each other.

[0100] The wastewater desalination treatment system provided by the present invention is characterized in that high-salt wastewater passes through the nanofiltration interception module 3, the microbial treatment module 4, and the electrodialysis-reverse osmosis module 5 provided in the system. First, the high-salt wastewater can be intercepted and separated in the nanofiltration interception module 3 to obtain monovalent salt wastewater and divalent salt wastewater. The monovalent salt wastewater and the divalent salt wastewater are then treated respectively by the electrodialysis-reverse osmosis module 5 and the microbial treatment module 4. The monovalent salt wastewater is treated by the electrodialysis-reverse osmosis module 5 to obtain recyclable industrial salt sodium chloride, and the divalent salt wastewater is treated by the microbial treatment module 4 to obtain recyclable elemental sulfur. That is, the wastewater desalination treatment system and treatment process provided by the present invention can react sulfate and chloride ions in high-salt wastewater into elemental sulfur and sodium chloride respectively for recovery and treatment, and has high wastewater treatment efficiency and low energy consumption.

[0101] The following is a detailed description of the electro-Fenton-air flotation combined treatment module 1 provided by the present invention. Figures 6-17 .

[0102] like Figure 1 、 Figure 5-Figure 8 As shown, the wastewater desalination treatment system provided by some embodiments of the present invention further includes a pretreatment module, which includes an electro-Fenton-flotation combined treatment module 1 and a tubular membrane filtration device 8 that are connected in sequence.

[0103] The electro-Fenton-flotation combined treatment module 1 includes an electrochemical precipitation device 101, an air flotation dissolved gas device 102 and an air source; the electrochemical precipitation device 101 includes an electrochemical reaction cell 103, in which a precipitation module, a water inlet module, an electrochemical module and a water production collection module are sequentially arranged from bottom to top; the electrochemical module includes a plurality of electrochemical units spaced apart in a vertical direction, each electrochemical unit includes an anode 104 and a cathode aeration pipe 105, and an anode filling pipe 106 is provided between adjacent electrochemical units. Material; the flotation and dissolution device 102 includes an outer shell 106, a water ejector 107, a water inlet pipe 108, an air inlet pipe 109 and a water supply pipe 110, the outlet end of the water ejector 107 is connected to the inner cavity of the outer shell 106, the water inlet pipe 108 and the air inlet pipe 109 are respectively connected to the water ejector 107, and the inlet end of the water supply pipe 110 is connected to the inner cavity of the outer shell 106; the water production collection module is connected to the water inlet pipe 108, the outlet end of the water supply pipe 110 is connected to the cathode aeration pipe 105, and the gas source is connected to the air inlet pipe 109.

[0104] The tubular membrane filtration device 8 has a water inlet and a water outlet, and the water outlet of the tubular membrane filtration device 8 is connected to the water inlet of the first nanofiltration device 301 .

[0105] In a specific embodiment of the present invention, the main part of the electrochemical precipitation device 101 is a cylindrical tank with an opening at the upper end, and the inner cavity of the tank serves as an electrochemical reaction cell 103. Three electrochemical units are spaced apart in the electrochemical reaction cell 103, and anode fillers are provided between adjacent electrochemical units, wherein the anode fillers include sintered sphere consumables composed of iron, hydroxy iron and hydroxy aluminum and other necessary components, with a diameter between 20 mm and 30 mm, which need to be replenished after a period of use. In some embodiments, a supporting filter plate 111 (or supporting filter screen) can be provided below the electrochemical unit located at the lowermost side, and the supporting filter plate 111 is evenly distributed with through holes, so that it can play a supporting role for the filler, and at the same time, it can also supply water to the upward flowing water and allow the sinking sediment to pass through.

[0106] It should be noted that, in some embodiments, the number of electrochemical units may be two or more than three, which is not specifically limited in the present invention.

[0107] In a specific embodiment of the present invention, the sedimentation module includes a mud discharge port 112 disposed at the bottom of the electrochemical reaction cell 103. A sedimentation zone 113 is formed between the water inlet module and the bottom of the electrochemical reaction cell 103. The dense flocculent sediment and sludge generated by the electrochemical reaction are deposited in the sedimentation zone 113 and discharged through the mud discharge port 112. In addition, a normally closed inspection port 114 can be provided at the bottom of the electrochemical reaction cell 103 to facilitate maintenance work.

[0108] In an embodiment of the present invention, the anode 104 includes a substrate on which an oxidation reaction layer is provided. Specifically, the substrate of the anode 104 can be made of titanium or stainless steel, and the oxidation reaction layer can be a ruthenium-iridium coating, which can be provided on the surface of the titanium or stainless steel by electroplating.

[0109] like Figure 10 As shown, in this embodiment of the present invention, the cathode aeration tube 105 includes a main aeration tube 1051 and multiple branch aeration tubes 1052 connected to the main aeration tube 1051. The branch aeration tubes 1052 include an inner aeration tube 1052a and a protective sleeve 1052b coaxially arranged from the inside out. A reduction reaction layer 1052c is provided between the inner aeration tube 1052a and the protective sleeve 1052b. The walls of the inner aeration tube 1052a and the protective sleeve 1052b are uniformly provided with air outlet holes. As an example, the inner aeration tube 1052a can be a porous tube made of SS316, the reduction reaction layer 1052c can be a carbon fiber sleeve (ACF), NT nanotubes, or reticulated glassy carbon (RVC), and the protective sleeve 1052b can be a porous PVC protective tube.

[0110] like Figure 7 and Figure 9As shown, in this embodiment of the present invention, the anode 104 is mesh-shaped, and in each electrochemical unit, the cathode aeration tube 105 is positioned below the anode 104. Specifically, the mesh-shaped anode 104 can be welded from multiple staggered rods of metal (a substrate with an oxidation reaction layer), providing support for the anode filler and increasing the reaction area. Placing the cathode aeration tube 105 below the anode 104 provides sufficient gas contact with the anode filler, improving electrochemical reaction efficiency.

[0111] The following is an example of the power supply connection between the anode 104 and the cathode in the electrochemical precipitation device 101 provided by the present invention. Figure 7 、 Figure 10 and Figure 12 .

[0112] like Figure 7 、 Figure 10 and Figure 12 As shown, in a specific embodiment of the present invention, anode terminals 115 are provided on the four sides (top, bottom, left, and right in the figure, and the same applies below) of the meshed anode 104, and four cathode terminals 116 are provided on the four sides of the cathode aeration tube 105. Anode terminals 115 and cathode terminals 116 are electrically connected to the anode and cathode of a power supply via wires, respectively. As an example, the power supply can be a DC pulse power supply with adjustable current and voltage, a duty cycle of 50%, and a pulse frequency of 0.15 kHz to 0.2 kHz. Each electrochemical unit uses an independent power supply that can be adjusted according to wastewater quality and treatment effect, with a current density of 16.8 mA / cm 2 .

[0113] like Figure 13 As shown, in an embodiment of the present invention, the water inlet module includes a water distribution main pipe 117 and multiple water distribution branch pipes 118 connected to the water distribution main pipe 117, and the water distribution branch pipes 118 are provided with water outlet holes. The water distribution branch pipes 118 can evenly distribute the incoming water into the electrochemical reaction cell 103, thereby improving the electrochemical treatment effect. In a further embodiment of the present invention, the water outlet holes of the water distribution branch pipes 118 are arranged downward. Firstly, they can provide a certain buffering effect on the incoming water; secondly, they can also prevent convection with the flocculent sediment and sludge settling downward, which would affect the sedimentation efficiency.

[0114] like Figure 14 and Figure 15 As shown, in this embodiment of the present invention, the produced water collection module includes a water collection assembly, which includes a water collection main pipe 119 and multiple water collection branch pipes 120 connected to the water collection main pipe 119. The water collection branch pipes 120 are provided with water inlet holes. The simultaneous water collection and processing by multiple water collection branch pipes 120 can improve water collection efficiency.

[0115] like Figure 14As shown, in an embodiment of the present invention, the produced water collection module further includes a drainage assembly; the drainage assembly includes a drainage trough 121 and a water level regulator 122. The drainage trough 121 is connected to the water outlet end of the water receiving main pipe 119. The water level regulator 122 includes an adjusting sleeve 1221. The adjusting sleeve 1221 is sleeved on the water outlet end of the water receiving main pipe 119 and is suitable for adjusting the water outlet level of the water receiving main pipe 119. The drainage trough 121 is provided with a drainage outlet. Specifically, the water outlet end of the water receiving main pipe 119 is vertically upward and has an external thread. The adjusting sleeve 1221 has an internal thread that matches the external thread. Through the threaded connection, the height of the water outlet of the adjusting sleeve 1221 is easily adjusted (by providing a handwheel 1222 on the adjusting sleeve 1221 to drive the adjusting sleeve 1221 to rotate), so as to control the water level of the produced water to be lower than the lowest point of the slag discharge port 125.

[0116] like Figure 7 、 Figure 16 and Figure 17 As shown, in some embodiments of the present invention, the electrochemical precipitation device 101 further includes a scraping module, which includes a scraper 123, a slag discharge trough 124, and a drive assembly suitable for driving the scraper 123 to rotate. The scraper 123 is arranged on the upper part of the electrochemical reaction cell 103, and the electrochemical reaction cell 103 is provided with a slag discharge port 125 connected to the slag discharge trough 124. Specifically, the scraper 123 adopts a hyperbolic scraper, and the curvature of the curved side gradually decreases from the radially outward direction, so as to facilitate scraping the slag floating on the water surface into the slag discharge trough 124. The slag collected in the slag discharge trough 124 can be discharged through the slag discharge port 125.

[0117] like Figure 16 and Figure 17 As shown, in a further embodiment of the present invention, the drive assembly includes a drive motor 126, which is in transmission connection with the scraper 123. Specifically, the drive assembly is connected to the center of the scraper 123 using a reducer 128. The speed of the reducer 128 can be set to 5 to 15 rpm, which can reduce the rotation speed of the scraper 123 to adapt it to scraping conditions. In addition, a mounting plate 129 is provided on the top of the electrochemical reaction cell 103, and a fixing base 130 is provided on the mounting plate 129. The motor and reducer 128 can be fixed to the fixing base 130 using bolts or other means.

[0118] In a specific embodiment of the present invention, a circulation pump 131 is installed in the pipeline connecting the produced water collection module and the water inlet pipe 108 to drive the wastewater to circulate within the system. Regulating valves can be installed before and after the circulation pump 131 to control the flow of the pipeline. The gas source can be an air pump or other gas storage device.

[0119] like Figure 8As shown, in the embodiment of the present application, the outlet end of the water jetting device 107 is provided with an expansion pipe 132 and a spray pipe 133, the outlet end of the expansion pipe 132 is communicated with the inlet end of the spray pipe 133; the inner cavity of the outer shell 106 is sequentially provided with a first partition plate 134, a second partition plate 135 and a third partition plate 136 from top to bottom, the first partition plate 134 is arranged below the inlet end of the water supply pipe 110, the second partition plate 135 is arranged below the outlet end of the expansion pipe 132, the third partition plate 136 is arranged below the outlet end of the spray pipe 133, and the first partition plate 134, the second partition plate 135 and the third partition plate 136 are all provided with through holes. By arranging the expansion pipe 132, the spray pipe 133, the first partition plate 134, the second partition plate 135 and the third partition plate 136, the gas and the liquid can be mixed more fully, so that the water at the water supply pipe 110 has better gas mixing and dissolving effect, and is supplied to the cathode aeration pipe 105. In addition, the multiple partition plates arranged at intervals can also increase the structural strength of the outer shell 106.

[0120] In the specific embodiment of the present application, the inlet end of the water supply pipe 110 is provided with a filter screen 137 to pass solid impurities. In some embodiments, a pressure detection device 127 for detecting the pressure in the inner cavity of the outer shell 106 is further included.

[0121] The working process of the electro-Fenton-air floatation combined treatment module 1 provided by the present application will be described in detail below. Please refer to Figure 6-Figure 8 .

[0122] The wastewater and the gas enter the water jetting device 107 for mixing through the water inlet pipe 108 and the gas inlet pipe 109 respectively, and are then sprayed out through the expansion pipe 132 and the spray pipe 133. Under the action of the small holes arranged on the first partition plate 134, the second partition plate 135 and the third partition plate 136, the gas can be better mixed into the wastewater, and the wastewater fully dissolved with the gas enters the cathode aeration pipe 105 through the water supply pipe 110. At the same time, the electrochemical precipitation device 101 passes the wastewater through the water inlet module, the wastewater flows upward, reacts in the electrochemical module, and the generated flocculating precipitate and sludge with large mass fall to the precipitation module, and the floating dregs with small mass float to the surface of the wastewater and are removed through the dregs scraping module. Part of the produced water can be discharged to the outside of the system through the produced water collection module, and part of the produced water continues to be treated in the system under the action of the circulating pump 131.

[0123] As can be known from the above description of the embodiments, the electro-Fenton-air floatation combined treatment module 1 provided by the present application has at least the following advantages:

[0124] (1) The two processes of flotation and electro-Fenton removal of inorganic pollutants such as metal ions and removal of difficult-to-biodegrade organic pollutants are combined. The complex processes of traditional wastewater treatment are simply integrated into one device, and the functions of redox decomposition, electro-stabilization, electro-complexation, electrode adsorption, coagulation, flotation removal, flocculation and sedimentation are all performed on one device. The process is simplified and can be completed by controlling only the voltage, current and frequency of the power supply.

[0125] (2) There is no need for complicated dosing. No other substances are introduced into the wastewater treatment water body or as little as possible to avoid secondary pollution. Electricity is used instead of adding various chemicals during the treatment process, and the application range is very wide.

[0126] (3) The reaction conditions are mild, the process is simple and reliable, the parameters are easy to control, and the operating costs are low.

[0127] like Figure 1 As shown, the wastewater desalination treatment system provided by some embodiments of the present invention further includes a sludge thickening tank 9 and a sludge dewatering device 10. The inlet end of the sludge thickening tank 9 is connected to the outlet end of the flocculation sedimentation tank 102, and the outlet end of the sludge thickening tank 9 is connected to the inlet end of the sludge dewatering device 10. By providing the sludge thickening tank 9 and the sludge dewatering device 10, the sludge discharged from the bottom of the flocculation sedimentation tank 102 can be concentrated and dewatered in sequence.

[0128] like Figure 1 As shown, in some embodiments of the present invention, a resin adsorption reaction device 11 is provided between the tubular membrane filtration device 8 and the first nanofiltration device 301. The resin adsorption reaction device 11 is suitable for removing at least one of residual hardness, heavy metal ions and residual COD in the wastewater. Specifically, the resin adsorption reaction device 11 can accurately remove the residual hardness, heavy metal ions and residual COD in the wastewater through weak acid cation resin and chelating resin. After pretreatment and treatment with the resin adsorption reaction device 11, the remaining ions in the wastewater are basically Cl - 、 and Na + , which is convenient for subsequent treatment of wastewater.

[0129] like Figure 1As shown, in some embodiments of the present invention, a second reverse osmosis device 12 is provided between the resin adsorption reaction device 11 and the first nanofiltration device 301, and the second reverse osmosis device 12 is suitable for concentrating the wastewater. When the concentration of chloride ions and sulfate ions in the wastewater does not reach the set value, the wastewater can be concentrated by the second reverse osmosis device 12, and after the concentration treatment, it enters the nanofiltration interception module 3 for treatment. In addition, before entering the second reverse osmosis device 12, the wastewater in the resin adsorption reaction device 11 can also be treated by a carbon dioxide remover and a security filter to remove carbon dioxide and fine particulate impurities in the wastewater to meet the water requirements of the second reverse osmosis device 12.

[0130] like Figure 1 and Figure 18 As shown, the wastewater desalination treatment system provided by some embodiments of the present invention also includes an MVR module 6, which includes an inlet water preheater 601, a buffer device 602, a falling film evaporator 603, a vapor-liquid separator 604, a steam compressor 605 and a heat pump unit 606; the inlet water preheater 601, the buffer device 602, the falling film evaporator 603 and the vapor-liquid separator 604 are connected in sequence, one side of the steam compressor 605 is connected to the vapor phase outlet of the vapor-liquid separator 604, and the other side of the steam compressor 605 is connected to the steam inlet of the falling film evaporator 603, the condensed water outlet of the falling film evaporator 603 is connected to the inlet water preheater 601, and the heat pump unit 606 is suitable for providing a heat-conducting medium to the buffer device 602 for heating.

[0131] Specifically, if Figure 18 As shown, the wastewater is first heat-exchanged with the condensed water discharged from the falling film evaporator 603, and then secondary heated by the high-temperature heat source heat transfer medium produced by the heat pump unit 606 to make the water temperature reach 100°C. After the high-temperature water enters the falling film evaporator 603, it is mixed and heated using the steam generated by the mechanical vapor recompression technology (MVR).

[0132] In some embodiments, the falling film evaporator 603 can adopt a double water distribution system to ensure that the brine is evenly and fully distributed on the inner wall of each tube, so that the inside of each tube remains moist and prevents scaling. The falling brine film absorbs latent heat from the water vapor condensed in the shell side and evaporates. The secondary steam generated by evaporation passes through the demister and enters the steam compressor 605 for temperature and pressure increase. After obtaining energy, the secondary steam returns to the falling film evaporator 603 and is reused as a heat source. The condensate generated by the falling film evaporator 603 enters the condensate tank and is pumped into the water inlet preheater 601 by the condensate pump. Part of its heat is recovered, the temperature drops, and finally it is recycled as high-quality condensate.

[0133] Features of Falling Film Evaporator 603: Falling Film Evaporator 603 is a falling film type and steam driven highly energy efficient system. Figure 19 and Figure 20 As shown, the circulating brine is pumped to the top pipe box by a circulating pump, where a dedicated liquid distribution system diverts the descending liquid film along each pipe. As the brine descends through the pipes, a small amount of water evaporates due to the heat generated by the condensation of steam outside the pipes. Process steam and the descending brine flow out of the bottom of the pipes. The brine descends back into the brine tank and circulates back to the top water distribution system. The process steam and descending brine are separated from each other. After the mist is removed from the top of the brine tank by the vapor-liquid separator 604, part of the steam is withdrawn by the steam compressor 605 for reuse, and part of the steam enters the condenser for condensation.

[0134] The secondary steam generated by the falling film evaporator 603 passes through a demisting and separation device to remove entrained droplets. After being heated and saturated at a higher pressure by a steam compressor 605, it enters a forced circulation heat exchanger (a heater within the falling film evaporator 603) to serve as a heat source for the system, reusing the steam's latent heat. Therefore, the falling film evaporator 603 requires steam during startup. After stable operation, the primary heat source for the system is the secondary steam recovered by the steam compressor 605.

[0135] like Figure 18 As shown, the wastewater desalination treatment system provided by some embodiments of the present invention also includes an evaporation crystallization module 7, which includes a thickener 701, a centrifugal filter 702, an evaporation crystallization unit 703, a centrifugal dehydrator 704 and a dryer 705; the water inlet end of the thickener 701 is connected to the liquid phase outlet of the vapor-liquid separator 604, and the outlet end of the thickener 701 is connected to the water inlet end of the centrifugal filter 702.

[0136] Specifically, thickener 701 concentrates suspended solid particles in the wastewater discharged from the liquid phase outlet of vapor-liquid separator 604, removing fine particulate impurities. The wastewater then enters centrifugal filter 702 to further remove any remaining particulate impurities. The wastewater is then fed into evaporation and crystallization unit 703, which includes a plate cooler, a cooling crystallization tank, a circulation pump, a steam jet vacuum system, a centrifugal dehydrator 704, a centrifugal mother liquor tank, and corresponding pumps. Evaporation and crystallization unit 703 evaporates and crystallizes the wastewater, forming a sodium chloride slurry. The slurry produced by the evaporation crystallization unit 703 is pumped into a centrifugal dehydrator 704. Centrifugal dehydrator 704 uses a spiral screen centrifuge to remove most of the water from the slurry, resulting in sodium chloride crystals (granular solid material) with a small amount of residual moisture. The remaining moisture is then removed by dryer 705 (exemplified by a fluidized bed dryer). The fluidized bed dryer comprises an air filter, a fluidized bed unit, a cyclone separator, a bag filter, a high-pressure centrifugal fan, and an operating table. Granular solid material is fed into the fluidized bed dryer via a feeder. The filtered, clean air is heated and then fed by a blower into the bottom of the fluidized bed. It then contacts the solid material through a distribution plate, forming a fluidized state and achieving heat and mass exchange between the gas and the solid. After drying, the material is discharged through a discharge port. Exhaust gas exits the top of the fluidized bed, where it is recovered through a cyclone and bag filter, and then discharged to the atmosphere. Fluidized bed dryers can be automated and are continuous drying equipment. They offer high drying speeds and low temperatures, ensuring high production quality. At this point, a higher purity of first-grade industrial salt sodium chloride can be obtained.

[0137] like Figure 1 As shown, the wastewater desalination treatment system provided by some embodiments of the present invention further includes a bipolar membrane electrodialysis module 13 , and the bipolar membrane electrodialysis module 13 is connected to the water outlet end of the electrodialysis device 501 .

[0138] Bipolar membrane electrodialysis (BMED) is a new type of separation technology in membrane separation technology. It is a technology that uses a combination of bipolar membrane and monopolar membrane. Since using bipolar membrane to split water is more economical than direct electrolysis of water, combining it with monopolar membrane can achieve multiple functions and has applications in many fields, especially in the treatment of some typical chemical wastewater. In the electric field, water will split in the middle layer of the bipolar membrane to generate H + and OH - In this way, the salt in the chemical wastewater can be separated and converted into the corresponding acid and alkali. Therefore, this method can not only remove the salt in the wastewater, but also recycle resources. Figure 21 shown.

[0139] The wastewater desalination treatment system provided by some embodiments of the present invention also includes a magnetoelectric composite scale inhibition and sterilization device 2, which includes a reactor, an electric field generating module, and a magnetic field generating module. The reactor is provided with a water inlet and a drain. The electric field generating module includes an ion generator disposed within the reactor's inner cavity and adapted to generate an electrostatic field between the ion generator and the reactor's inner wall. The magnetic field generating module includes a first magnetic field generating unit and a second magnetic field generating unit disposed on either side of the reactor, adapted to generate an alternating magnetic field within the reactor's inner cavity. The drain port of the magnetoelectric composite scale inhibition and sterilization device 2 is connected to the water inlet of the first nanofiltration device 301. Before entering the first nanofiltration device 301, the wastewater is subjected to scale inhibition and sterilization treatment using the combined action of magnetic and electric fields. Ions in the wastewater form scale, preventing clogging of the filter membrane. The structure is simple and does not introduce other agents into the raw water.

[0140] The following is a detailed description of the magnetic-electric composite scale prevention and sterilization device 2. Please refer to Figure 22-26 .

[0141] like Figure 22 and Figure 23 As shown, the present invention provides a magnetoelectric composite scale inhibition and sterilization device, comprising a reactor 201, an electric field generating module, and a magnetic field generating module. The reactor 201 is provided with a water inlet 202 and a water outlet 203. The electric field generating module includes an ion generator 204, which is disposed within the inner cavity of the reactor 201 and is adapted to generate an electrostatic field between the ion generator 204 and the inner wall of the reactor 201. The magnetic field generating module includes a first magnetic field generating unit and a second magnetic field generating unit, respectively disposed on either side of the reactor 201, and adapted to generate an alternating magnetic field within the inner cavity of the reactor 201.

[0142] In a specific embodiment of the present invention, the reactor 201 is made of a metal can, the water inlet 202 and the drain outlet 203 are respectively arranged at the lower end and the upper end of the reactor 201, the electric field generating module, the first magnetic field generating unit and the second magnetic field generating unit are arranged on the side wall of the reactor 201, and the first magnetic field generating unit and the second magnetic field generating unit are arranged opposite to each other, and the ion generator 204 is installed crosswise with the first magnetic field generating unit and the second magnetic field generating unit, so as to facilitate the combined treatment of cutting the electrostatic field and the alternating magnetic field when the incoming water flows along the direction from the water inlet 202 to the water outlet.

[0143] In a specific embodiment of the present invention, the ion generator 204 is a high-voltage electrostatic field ion generator; the magnetic field generating module is capable of forming a high-frequency, low-pressure pulse magnetic field in the inner cavity of the reactor 201 .

[0144] The magnetoelectric composite scale inhibition and sterilization device provided by the present invention can form an electrostatic field and an alternating magnetic field in the inner cavity of the reactor 201 by setting an electric field generating module and a magnetic field generating module. When the wastewater flows in the inner cavity of the reactor 201 from the water inlet 202 to the water outlet, the electrostatic field and the alternating magnetic field are cut through composite treatment to achieve the technical purpose of scale inhibition and sterilization. The structure is simple and no other agents are introduced into the raw water.

[0145] like Figure 24 As shown, in this embodiment of the present invention, the electric field generating module further includes a guide rod 205 and a wire 206 . The guide rod 205 is electrically connected to the ion generator 204 , and the first end (left end in the figure) of the wire 206 is electrically connected to the guide rod 205 . Specifically, the main body of the ion generator 204 is a hollow metal ball, and the guide rod 205 includes a metal pull bolt 205a and a hollow metal rod 205b. One end of the metal rod 205b is fixedly connected to the metal ball. The metal pull bolt 205a is arranged inside the metal rod 205b and both ends thereof extend out of the metal rod 205b. Its first end (the left end in the figure) extends into the interior of the ion generator 204 and is provided with a limit block 207. Its second end (the right end in the figure) is provided with a threaded section, and two fastening nuts 208 and a clamping nut 209 are provided on the threaded section in sequence. The first end of the wire 206 is pressed between the fastening nut 208 and the clamping nut 209. The two clamping nuts 209 can press and fix the metal pull bolt 205a to prevent it from axial movement, and the fastening nut 208 and the clamping nut 209 can fix the first end of the wire 206 while ensuring that it has a good electrical connection with the metal pull bolt 205a. In a specific embodiment of the present invention, the metal ball and the metal rod 205b can be made of aluminum material, and the two are connected by welding, bolt connection, etc., or they can be set as one body. Alternatively, the metal pull bolt 205a can be made of copper material.

[0146] like Figure 24 As shown, in this embodiment of the present invention, the electric field generating module further includes an insulating jacket 210, which is disposed over the ion generator 204 and guide rod 205. The insulating jacket 210 prevents wastewater from coming into contact with the metal ball, metal rod 205b, metal pull bolt 205a, and nut, etc., made of the aforementioned metal materials, thereby protecting these metal components from corrosion by the wastewater. Because the aforementioned metal components are lightweight and the insulating jacket 210 has a certain thickness, it can provide a certain strength while enveloping the aforementioned metal components, thereby securing them. Specifically, the insulating jacket 210 can be manufactured from PTFE (polytetrafluoroethylene).

[0147] like Figure 24As shown, in this embodiment of the present invention, the electric field generating module further includes an insulating cover 211. The reactor 201 is provided with a clearance opening suitable for accommodating the guide rod 205. The insulating cover 211 covers the clearance opening, and the second end of the wire 206 (the right end in the figure) passes through the insulating cover 211 and is located outside the reactor 201. Because the ion generator 204 requires power from an external power source via the wire 206, a clearance opening is required in the reactor 201 to allow the rod portion of the insulating jacket 210 to extend outside the reactor 201. The provision of the insulating cover 211 effectively insulates and seals the clearance opening.

[0148] like Figure 24 As shown, in this embodiment of the present invention, a first flange plate 212 is provided on the reactor 201, and the insulating cover plate 211 is connected to the reactor 201 via the first flange plate 212. Specifically, the insulating cover plate 211 includes an insulating cover plate body 211a and an insulating cover plate flange 211b. The insulating cover plate body 211a is provided with through holes along its circumference, and the insulating cover plate flange 211b is provided with screw holes on its (radially) inner side that correspond to the through holes of the insulating cover plate 211, so that the insulating cover plate body 211a and the insulating cover plate flange 211b can be fixedly connected by screws. The first flange plate 212 is provided with through holes along its circumference, and the insulating cover plate flange 211b is provided with through holes on its (radially) outer side that correspond to the through holes of the first flange plate 212. The insulating cover plate flange 211b can be fixed to the first flange plate 212 via bolts and nuts. This structure is simple and easy to assemble and disassemble. In a further embodiment of the present invention, the above-mentioned insulating jacket 210 can be integrated with the insulating cover body 211a, and at this time, a sealing groove is provided on the side surface where the insulating cover body 211a and the insulating cover flange 211b are in contact, and an O-ring is provided in the sealing groove to ensure the water tightness of the device and prevent wastewater from overflowing.

[0149] like Figure 25 As shown, in an embodiment of the present invention, the first magnetic field generating unit and the second magnetic field generating unit each include three core assemblies, and the core assemblies in the first magnetic field generating unit and the second magnetic field generating unit are arranged along the flow direction of the wastewater. The core assemblies are wound with coils 213. When current is passed through coils 213, a magnetic field is formed in the inner cavity of reactor 201, exerting a magnetic field effect on the wastewater. It is foreseeable that in some embodiments, the first magnetic field generating unit and the second magnetic field generating unit may also include other numbers of core assemblies, such as one, two, or four, and the present invention does not specifically limit this.

[0150] like Figure 23 and Figure 25As shown, as an example, the number of turns of the coil 213 wound around each core assembly is 300 turns, which is the condition for generating the maximum magnetic field. The coils A and A' are a group, B and B' are a group, and C and C' are a group. Taking the A-A' group as an example, the incoming end of the enameled wire of A is a, and the outgoing end is a', then a' is the incoming end of A', and the outgoing end of A' is a", and the incoming wires a, b, and c of the three groups of coils are connected together as the total incoming end and connected to one electrode of the power supply, and the outgoing wires a", b", and c" (b" and c" are not shown in the figure) are connected together and connected to the other electrode of the power supply.

[0151] like Figure 25 As shown, in a specific embodiment of the present invention, the core assembly includes a metal sleeve 214 and a metal inner core 215. The metal sleeve 214 is sleeved on the metal inner core 215, and the coil 213 is wound around the metal sleeve 214. The metal sleeve 214 can be made of iron or stainless steel, the metal inner core 215 can be made of IJ85 nickel-iron soft magnetic alloy, and the coil 213 can be made of copper enameled wire with an insulating outer sheath. In addition, an insulating retaining ring is provided at the end of the metal sleeve 214 for insulation and limiting axial movement of the metal inner core 215. The insulating retaining ring can be fixedly connected to the metal inner core 215 by screws.

[0152] like Figure 23 As shown, in a specific embodiment of the present invention, a second flange plate 216 and a third flange plate 217 are respectively provided on either side of the reactor 201. The first magnetic field generating unit also includes a fourth flange plate 218, and the second magnetic field generating unit also includes a fifth flange plate 219. The first magnetic field generating unit is connected to the reactor 201 via the fourth flange plate 218 and the second flange plate 216, while the second magnetic field generating unit is connected to the reactor 201 via the fifth flange plate 219 and the third flange plate 217. The first and second magnetic field generating units can be fixed to either side of the reactor 201 using bolts and nuts, and assembly and disassembly are simplified. Furthermore, the fourth and fifth flange plates 218 and 219 have multiple through-holes. One end of the metal sleeve 214 of each core assembly in the first magnetic field generating unit is integrally connected or welded to the fourth flange plate 218, while one end of the metal sleeve 214 of each core assembly in the second magnetic field generating unit is integrally connected or welded to the fifth flange plate 219.

[0153] In some embodiments, the metal inner core 215 is provided with a sealing groove along its circumference, within which an O-ring is installed. Since the second flange plate 216, the third flange plate, and the reactor 201 are provided with corresponding openings for magnetic flux lines to pass through, by integrating the metal sleeve 214 with the corresponding flange plate and installing an O-ring between the metal inner core 215 and the metal sleeve 214, this not only ensures that the corresponding core assembly forms a complete magnetic flux line under the action of the coil 213, but also provides a sealing function through the sealing ring, preventing water from flowing out of the inner cavity of the reactor 201.

[0154] In an embodiment of the present invention, the electric field generating module further includes a first power supply, and the magnetic field generating module further includes a second power supply. For example, the first power supply can be a high-voltage DC power supply with an output voltage level no greater than 10,000 volts, and the current level can be adjusted on-site based on the impurity content of the brine. The second power supply can be a low-voltage square wave pulse power supply with an input voltage of 220V and an input frequency of 50Hz. This design power supply has an output frequency of 300Hz and a duty cycle of 50%. The coil is constructed with an IJ85 nickel-iron soft magnetic alloy core, and a single coil can generate a magnetic field of 251.758Gs.

[0155] The scale inhibition and sterilization principles of the magnetoelectric composite scale inhibition and sterilization device provided by the present invention are described in detail below. Figure 22-26 .

[0156] The electric field generating module and the magnetic field generating module form a high-voltage electrostatic field and a high-frequency low-voltage pulse magnetic field in the inner cavity of the reactor 201. On the one hand, the water dipole molecules are directionally polarized, the distance between the positive and negative charge centers in the water molecules increases, the dipole moment and polarity of the water molecules increase, the hydrogen bonds of the water molecule structure are elongated, the water molecule clusters become small water molecule clusters, the electromagnetic energy is converted into the internal energy of the water molecules, and the activation degree of the water molecules is increased; on the other hand, when the pulse wave is passed through the coil 213, at the moment of pulse on and off, the energy accumulated in the coil 213 generates a recoil high voltage at both ends of the coil 213 due to the sudden closure of the circuit, which instantly increases the induced voltage in the water, and the pulse magnetic energy reaches the maximum transmission. At the same time, when the applied pulse frequency is close to or proportional to the water molecule frequency, the "resonance" with the water molecules is intensified, the positive and negative charge centers of the water molecules deflect periodically with the pulse frequency, the water molecule dipoles are repeatedly polarized, and the activation degree is further increased. The activated water molecules have an effect on Ca in water. 2+ (water) and The hydration of (water) ions is enhanced, which hinders the accumulation of microcrystals to form solid hard scale, increases the tendency of scale to dissolve in water, and reduces the tendency to precipitate and form CaCO3 scale, thereby achieving the purpose of scale inhibition.

[0157] Sterilization using alternating electromagnetic fields utilizes electromagnetic energy to destroy or affect the structure of microorganisms, thereby eliminating or inhibiting them. Alternating magnetic fields produce various electromagnetic effects, including induced current, Lorentz force, oscillation, and ionization. These electromagnetic effects induce biological responses in cells, significantly impacting the sterilization process.

[0158] It is foreseeable that, in some embodiments, a magneto-electric composite scale inhibition and sterilization device may be provided before other membrane treatment processes.

[0159] like Figure 27 As shown, the present invention also provides a wastewater desalination treatment process based on the wastewater desalination treatment system described in the above embodiment, comprising:

[0160] The wastewater is passed through the nanofiltration interception module 3, where the sulfate and chloride ions in the wastewater are intercepted and separated by the first nanofiltration device 301, the second nanofiltration device 302, and the third nanofiltration device 303, respectively, to obtain monovalent salt wastewater and divalent salt wastewater. The monovalent salt wastewater is passed through the electrodialysis-reverse osmosis module 5, where the monovalent salt wastewater is concentrated by the electrodialysis device 501 and the first reverse osmosis device 502. The concentrated monovalent salt wastewater is then passed through the MVR module 6 for treatment to obtain sodium chloride.

[0161] The divalent salt wastewater is passed into the microbial treatment module 4, and the sulfate radicals in the divalent salt wastewater are reacted into elemental sulfur by the sulfate-reducing bacteria in the sulfate-reducing bacteria reaction device 401 and the denitrifying thiobacillus in the denitrifying thiobacillus reaction device 402 in sequence.

[0162] Specifically, during the treatment process of the nanofiltration retention module 3, the wastewater is first passed into the first nanofiltration device 301 for primary separation, and the water produced by the first nanofiltration device 301 is mixed with the water produced by the third nanofiltration device 303 and then enters the second nanofiltration device 302 for secondary retention to increase the retention rate of sulfate ions; at the same time, the concentrated liquid of the first nanofiltration device 301 and the concentrated liquid of the second nanofiltration device 302 are mixed and then enter the third nanofiltration device 303 for secondary recovery to increase the water recovery rate of the nanofiltration retention module 3 and further reduce the retention rate of chloride ions. Among them, the water produced by the second nanofiltration device 302 is the water produced by the nanofiltration retention module 3, and the concentrated liquid discharged from the third nanofiltration device 303 is the concentrated liquid of the nanofiltration retention module 3. The experimental results show that the average retention rate of the nanofiltration retention module 3 for different ions is as follows: Figure 28 shown.

[0163] The electrodialysis-reverse osmosis module 5 is suitable for treating monovalent salt wastewater obtained after nanofiltration. The electrodialysis-reverse osmosis module 5 combines the excellent concentration performance of homogeneous membrane electrodialysis at high salinity and the outstanding desalination performance of reverse osmosis at low concentration. Unlike reverse osmosis, the concentration limit of electrodialysis is not limited by osmotic pressure and can reach 20% using a suitable homogeneous membrane. Compared with DTRO (disc tube reverse osmosis) with a concentration limit of 12%, the electrodialysis-reverse osmosis module 5 reduces the amount of evaporated water by 40% with lower investment and roughly equivalent energy consumption, which also significantly reduces the overall investment and operating energy consumption of the zero-emission system.

[0164] The microbial treatment module 4 is suitable for treating the divalent salt wastewater obtained after nanofiltration. The sodium sulfate concentrate is treated by sulfate-reducing bacteria (SRB) in the sulfate-reducing bacteria reaction device 401, and combined with denitrifying thiobacillus (T-denitrificans) in the denitrifying thiobacillus reaction device 402 to produce elemental sulfur. Sulfate-reducing bacteria is a kind of amphipathic bacteria, which can be both organic chemoheterotrophic (mainly) and mineralized autotrophic (secondarily). Sulfate-reducing bacteria can use sulfate, sulfite, thiosulfate and the like as the final electron acceptor in the metabolic process, and is an anaerobic respiratory type of bacteria. In addition to being distributed in soil and fresh water, sulfate-reducing bacteria can also survive when the salt water concentration reaches 30%. The reduction reaction is as follows:

[0165]

[0166] Thiobacillus denitrificans is an obligate chemolithoautotrophic bacterium that obtains energy from the oxidation of sulfide and generates nitrogen gas using nitrate as an electron acceptor. Thiobacillus denitrificans is widely distributed and is a strict autotrophic bacterium that can only use inorganic carbon sources (such as carbonate ions and bicarbonate ions) for growth and metabolism. In the sulfur cycle system, under aerobic conditions, Thiobacillus denitrificans uses oxygen as an electron acceptor to oxidize and reduce sulfur compounds to obtain energy. Under anaerobic conditions, Thiobacillus denitrificans participates in the sulfur and nitrogen cycles simultaneously in the form of denitrification reactions, oxidizing sulfur compounds with the oxygen in nitrate. Sulfide-type denitrification using nitrate as an electron acceptor can be described by the following reaction formula:

[0167]

[0168] According to actual engineering, S / N (molar ratio, the same below) and sulfide concentration are the key factors affecting the denitrification and sulfur removal process of organic wastewater. It is recommended that good denitrification and sulfur removal effects can be obtained when S / N is controlled at 5 / 3 and the sulfide mass concentration is lower than 300 mg / L.

[0169] The advantages of microbial treatment module 4 are:

[0170] Sulfate-reducing bacteria and denitrifying Thiobacillus are both common natural bacterial species, which are easy to culture, strengthen and use in a targeted manner.

[0171] The sulfate-reducing bacteria reaction device 401 and the denitrifying Thiobacillus reaction device 402 have simple structures, low manufacturing costs, low operating costs, and do not require the addition of a large amount of reagents during the wastewater treatment process.

[0172] It can react sulfate ions in wastewater to generate sulfur-containing elemental sludge, which is a very good soil conditioner.

[0173] The concentrated water on the divalent salt side does not require energy-consuming evaporation (freezing) and crystallization, saving a lot of energy.

[0174] The system runs stably.

[0175] Some embodiments of the present invention provide a wastewater desalination process, further comprising:

[0176] Before the wastewater is passed into the nanofiltration interception module 3, the wastewater is passed into the pretreatment module for pretreatment, and the electrochemical precipitation device 1 and the tubular membrane filtration device 8 are used to remove some of the hardness, heavy metal ions, F - , total silicon and COD to obtain wastewater A;

[0177] Wastewater A is passed through a resin adsorption reaction device 11 to remove residual hardness, heavy metal ions and residual COD in wastewater A to obtain wastewater B;

[0178] The concentrations of sulfate and chloride ions in the wastewater B are detected. When the concentrations of sulfate and chloride ions in the wastewater B are lower than the set values, the wastewater is passed into the second reverse osmosis device 12 for concentration treatment.

[0179] Pretreatment is the fundamental method to ensure zero discharge of wastewater, and mainly involves the removal of suspended solids and colloids, pH adjustment, COD reduction, softening, and heavy metal ion removal. The existing pretreatment process still has the following defects:

[0180] (1) In the pretreatment process of the existing technology, a three-tank high-density sedimentation tank is used to remove COD and hardness. The amount of flocculant added is very large, about 500mg / L to 1000mg / L, and the turbidity of the produced water is acceptable. However, due to the removal of F - 1. COD removal is best achieved at pH 7-8, while hardness removal is best achieved at alkaline conditions at pH 11 to 12, so it needs to be operated in stages, that is, the five-tank treatment method, resulting in huge acid and alkali dosage and high operating costs.

[0181] (2) The ozone catalytic oxidation process is selective for difficult-to-degrade COD. However, due to the high salt content of wastewater (10,000 to 20,000), the efficiency of COD removal by ozone catalytic oxidation of concentrated brine is very low, operating at only 20%, which does not meet the requirements of subsequent salt evaporation system, membrane system stable operation and salt purity.

[0182] (3) COD does not meet the standard, causing foam to form in the evaporation chamber 603 of the concentrated brine (divalent salt) MVR falling film evaporator, the secondary steam is entrained with mist, and the compressor surges severely until it shuts down.

[0183] (4) The salt removal does not meet the standard, and the final liquid F - The ion content is greater than 50ppm, causing serious corrosion of equipment and corrosion of titanium metal; As a result, the purity of the salt does not meet the standard requirements.

[0184] The pretreatment process in the wastewater desalination process proposed by the present invention, through the coupling effect of the electrochemical precipitation device 1 and the tubular membrane filtration device 8 (the pretreatment principles of the two are described above), the treatment process only consumes electricity, which is one tenth of the conventional electro-Fenton process; there is no need to add a large amount of reagents, H2O2 and Fe 2+ It can be generated in situ; and the experimental results show that the treatment efficiency of the electro-Fenton method using the electrochemical precipitation device 1 is 10,000 times higher than that of the traditional Fenton method due to a variety of degradation factors, including: anodic oxidation, electrosorption, electroflotation and electrochemical reaction, etc. - , Si and other impurities are completely removed; the electrode oxidation, self-produced Fenton reagent oxidation and hydroxyl radical oxidation reactions are complete, and the removal capacity of difficult-to-degrade COD is strong, which can reach a removal rate of more than 98%, and no secondary pollution is generated.

[0185] Some embodiments of the present invention provide a wastewater desalination process, further comprising:

[0186] The wastewater at the outlet of the electrodialysis device 501 is passed into the bipolar membrane electrodialysis module 13 to recover hydrogen chloride and sodium hydroxide in the wastewater.

[0187] The principles and advantages of using the bipolar membrane electrodialysis module 13 for treatment in the wastewater desalination process are described above and will not be repeated here.

[0188] From the description of the above embodiments, it can be seen that the wastewater desalination treatment system and treatment process provided by the present invention have at least the following advantages:

[0189] (1) Pretreatment: Through the coupling effect of electrochemical precipitation device 1 and tubular membrane filtration device 8, the treatment process only consumes electricity, which is one tenth of the conventional electro-Fenton process; there is no need to add a large amount of reagents, H2O2 and Fe 2+It can be generated in situ; and the experimental results show that the treatment efficiency of the electro-Fenton method using the electrochemical precipitation device 1 is 10,000 times higher than that of the traditional Fenton method due to a variety of degradation factors, including: anodic oxidation, electrosorption, electroflotation and electrochemical reaction, etc. - , Si and other impurities are completely removed; the electrode oxidation, self-produced Fenton reagent oxidation and hydroxyl radical oxidation reactions are complete, and the removal capacity of difficult-to-degrade COD is strong, which can reach a removal rate of more than 98%, and no secondary pollution is generated.

[0190] (2) The nanofiltration retention module 3 creatively combines the first nanofiltration device 301, the second nanofiltration device 302 and the third nanofiltration device 303, and by controlling the flow direction of the produced water and the concentrated liquid of each nanofiltration device, the retention efficiency of sulfate radical is high. The experimental results show that the membrane driving pressure is one-fifth lower than that of the existing high-salt membrane element, and the anti-fouling and clogging ability is strong;

[0191] (3) By setting up a microbial treatment module 4, sulfate-reducing bacteria and sulfate-reducing bacteria are used to treat sulfate ions and generate elemental sulfur with resource utilization value. The divalent salt concentrated water does not need to be evaporated, reducing the evaporation cost of wastewater treatment by nearly half;

[0192] (4) By setting up the MVR module 6, the energy efficiency of the evaporation process and the use of waste heat can be improved, and technologies such as factory waste heat heat pump preheating, solar energy, and electric energy coupled evaporation can be used;

[0193] (5) Expand the resource utilization of ultra-high concentrated brine, and use the bipolar membrane electrodialysis module 13 to produce HCl / NaOH, which has low energy consumption, high processing efficiency and long service life;

[0194] (6) By setting up a magnetoelectric composite anti-scaling and sterilizing device 2, the wastewater can be pre-treated by the magnetoelectric composite anti-scaling and sterilizing device 2 before entering the membrane treatment stage, thereby removing inorganic salts, colloids and microorganisms that are prone to scaling or producing suspended matter in the wastewater, reducing the risk of membrane contamination in the subsequent membrane treatment process without adding any chemicals;

[0195] (7) The sodium chloride produced by the wastewater desalination treatment system and treatment process provided by the present invention is in accordance with the secondary standard of refined industrial salt of GB / T5462-2015 Industrial Salt, with a purity of >97.5%, a whiteness of >82, and a salt resource utilization rate of >96%;

[0196] (8) The overall energy consumption of the project is significantly reduced compared with traditional processes.

[0197] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A wastewater desalination treatment system, characterized in that: include: A nanofiltration retention module, the nanofiltration retention module comprising a first nanofiltration device, a second nanofiltration device and a third nanofiltration device, the water production end of the first nanofiltration device being in communication with the water inlet end of the second nanofiltration device, the concentrated liquid outlet end of the first nanofiltration device being in communication with the water inlet end of the third nanofiltration device, the concentrated liquid outlet end of the second nanofiltration device being in communication with the water inlet end of the third nanofiltration device, and the water production end of the third nanofiltration device being in communication with the water inlet end of the second nanofiltration device; a microbial treatment module, the microbial treatment module comprising a sulfate-reducing bacteria reaction device and a denitrifying thiobacillus reaction device, the water inlet end of the sulfate-reducing bacteria reaction device being in communication with the concentrated liquid outlet end of the third nanofiltration device, the water outlet end of the sulfate-reducing bacteria reaction device being in communication with the water inlet end of the denitrifying thiobacillus reaction device, the sulfate-reducing bacteria reaction device being adapted to utilize sulfate-reducing bacteria to react sulfate radicals in the wastewater into divalent sulfide ions, and the denitrifying thiobacillus reaction device being adapted to utilize denitrifying thiobacillus to react divalent sulfide ions in the wastewater into elemental sulfur; an electrodialysis-reverse osmosis module, the electrodialysis-reverse osmosis module comprising an electrodialysis device and a first reverse osmosis device, the water production end of the second nanofiltration device being in communication with the water inlet end of the electrodialysis device, and the electrodialysis device and the first reverse osmosis device being in communication with each other; A magnetoelectric composite scale inhibition and sterilization device, comprising a reactor, an electric field generating module and a magnetic field generating module. The reactor is provided with a water inlet and a drain outlet. The electric field generating module comprises an ion generator, which is arranged in the inner cavity of the reactor. The ion generator is suitable for generating an electrostatic field between the ion generator and the inner wall of the reactor. The magnetic field generating module comprises a first magnetic field generating unit and a second magnetic field generating unit respectively arranged on both sides of the reactor. The first magnetic field generating unit and the second magnetic field generating unit are suitable for generating an alternating magnetic field in the inner cavity of the reactor. The ion generator is cross-mounted with the first magnetic field generating unit and the second magnetic field generating unit so that the inlet water can be cut by the electrostatic field and the alternating magnetic field composite treatment when flowing in the direction from the water inlet to the water outlet. The drain outlet of the magneto-electric composite scale inhibition and sterilization device is communicated with the water inlet end of the first nanofiltration device.

2. The wastewater desalination treatment system according to claim 1, characterized in that: It also includes a pre-treatment module, which includes an electro-Fenton-air flotation combined treatment module and a tubular membrane filtration device that are connected in sequence; The electro-Fenton-air flotation combined treatment module includes an electrochemical precipitation device, an air flotation and dissolution device, and an air source; The electrochemical precipitation device includes an electrochemical reaction cell, wherein a precipitation module, a water inlet module, an electrochemical module, and a produced water collection module are sequentially arranged from bottom to top in the electrochemical reaction cell; the electrochemical module includes a plurality of electrochemical units spaced apart in a vertical direction, each of the electrochemical units includes an anode and a cathode aeration tube, and anode fillers are filled between adjacent electrochemical units; The flotation and air dissolution device includes an outer shell, an ejector, a water inlet pipe, an air inlet pipe, and a water supply pipe. The outlet end of the ejector is in communication with the inner cavity of the outer shell, the water inlet pipe and the air inlet pipe are in communication with the ejector respectively, and the inlet end of the water supply pipe is in communication with the inner cavity of the outer shell; the produced water collection module is in communication with the water inlet pipe, the outlet end of the water supply pipe is in communication with the cathode aeration pipe, and the air source is in communication with the air inlet pipe. The tubular membrane filtration device is provided with a water inlet and a water outlet, and the water outlet of the tubular membrane filtration device is communicated with the water inlet of the first nanofiltration device.

3. The wastewater desalination treatment system according to claim 2, characterized in that: A resin adsorption reaction device is provided between the tubular membrane filtration device and the first nanofiltration device. The resin adsorption reaction device is suitable for removing at least one of residual hardness, heavy metal ions and residual COD in wastewater.

4. The wastewater desalination treatment system according to claim 3, characterized in that: A second reverse osmosis device is provided between the resin adsorption reaction device and the first nanofiltration device, and the second reverse osmosis device is suitable for concentrating wastewater.

5. The wastewater desalination treatment system according to claim 1, characterized in that: The MVR module includes a water preheater, a buffer device, a falling film evaporator, a vapor-liquid separator, a steam compressor and a heat pump unit; The water inlet preheater, the buffer device, the falling film evaporator and the vapor-liquid separator are connected in sequence, one side of the steam compressor is connected to the vapor phase outlet of the vapor-liquid separator, the other side of the steam compressor is connected to the steam inlet of the falling film evaporator, the condensed water outlet of the falling film evaporator is connected to the water inlet preheater, and the heat pump unit is suitable for providing a heat-conducting medium to the buffer device for heating.

6. The wastewater desalination treatment system according to claim 5, characterized in that: It also includes an evaporation crystallization module, which includes a thickener, a centrifugal filter, an evaporation crystallization unit, a centrifugal dehydrator and a dryer; The water inlet end of the thickener is communicated with the liquid phase outlet of the vapor-liquid separator, and the outlet end of the thickener is communicated with the water inlet end of the centrifugal filter.

7. The wastewater desalination treatment system according to claim 1, characterized in that: It also includes a bipolar membrane electrodialysis module, which is connected to the water outlet end of the electrodialysis device.

8. A wastewater desalination treatment process based on the wastewater desalination treatment system according to any one of claims 1 to 7, characterized in that: include: Passing the wastewater into the nanofiltration interception module, intercepting and separating sulfate and chloride ions in the wastewater by the first nanofiltration device, the second nanofiltration device, and the third nanofiltration device to obtain monovalent salt wastewater and divalent salt wastewater, respectively; Passing the monovalent salt wastewater into the electrodialysis-reverse osmosis module, concentrating the monovalent salt wastewater through the electrodialysis device and the first reverse osmosis device, and passing the concentrated monovalent salt wastewater into the MVR module for treatment to obtain sodium chloride; The divalent salt wastewater is passed into the microbial treatment module, and sulfate radicals in the divalent salt wastewater are reacted into elemental sulfur by the sulfate-reducing bacteria in the sulfate-reducing bacteria reaction device and the denitrifying thiobacillus in the denitrifying thiobacillus reaction device in sequence.

9. The wastewater desalination process according to claim 8, characterized in that: Also includes: Before the wastewater is passed into the nanofiltration interception module, the wastewater is passed into the pretreatment module, and some hardness, heavy metal ions, F - , total silicon and COD to obtain wastewater A; Passing the wastewater A into a resin adsorption reaction device to remove residual hardness, heavy metal ions and residual COD in the wastewater A to obtain wastewater B; The concentrations of sulfate and chloride ions in the wastewater B are detected. When the concentrations of sulfate and chloride ions in the wastewater B are lower than set values, the wastewater is passed into a second reverse osmosis device for concentration treatment.

10. The wastewater desalination process according to claim 8 or 9, characterized in that: Also includes: The wastewater at the outlet of the electrodialysis device is passed into a bipolar membrane electrodialysis module to recover hydrogen chloride and sodium hydroxide in the wastewater.

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