Two-stage concentrated water treatment-based low-agent self-regulating nanofiltration coupling system and use method

Abstract

A two-stage concentrated water treatment-based low-agent self-regulating nanofiltration coupling system and a use method. The system comprises: a water inlet tank, a drop aeration tower, a self-driven ecological membrane ultrafiltration filter, a nanofiltration water inlet tank, a first-stage nanofiltration membrane assembly, a nanofiltration produced water tank, an ion-exchange membrane electrolysis reactor, a ceramic membrane assembly, an alkali solution storage tank, an acid solution storage tank, a nanofiltration concentrated water regulating tank, a second-stage nanofiltration membrane assembly, and a salt solution tank. A concentrated water port of the first-stage nanofiltration membrane assembly, a cathode chamber, the ceramic membrane assembly, an anode chamber, the nanofiltration concentrated water regulating tank, and the second-stage nanofiltration membrane assembly are successively connected to form a concentrated water treatment system. An assembly cleaning system is formed by means of the salt solution tank, the ion-exchange membrane electrolysis reactor, the alkali solution storage tank, and the acid solution storage tank. Prediction indicators can be automatically detected, periodic cleaning can be carried out by means of self-regulation, and no other agents need to be added.

Description

Two-stage concentrated water treatment low-drug self-regulating nanofiltration coupling system and use method Technical Field

[0001] The present invention relates to a two-stage low-drug self-regulating nanofiltration coupling system for concentrated water treatment and a use method thereof, belonging to the technical field of water treatment. Background Art

[0002] Nanofiltration can simultaneously remove dissolved salts, emerging pollutants, small molecules of natural organic matter, pathogenic microorganisms, and colloids from water, and has been widely used to purify surface and groundwater of poor quality. However, during nanofiltration operation, microscopic processes such as inorganic scaling, microbial growth, and organic adsorption can occur, leading to composite membrane fouling and reduced flux stability. To mitigate composite membrane fouling, chemical agents such as scale inhibitors and biocides are often added during nanofiltration operations to achieve high flux and high recovery rates. However, the large amount of chemical addition presents challenges in the treatment and discharge of nanofiltration brine, leading to complex operations and maintenance. Over-reliance on chemical agents is a key issue in the widespread application of nanofiltration. Furthermore, low-pressure nanofiltration, the currently commonly used nanofiltration operation method, requires a driving pressure of 0.6-1.0 MPa. Compared to processes such as ultrafiltration, water production still consumes more energy and requires higher equipment requirements. Technical issues

[0003] The present invention aims to solve the problems of high dependence on chemical agents, high operating energy consumption and large maintenance requirements of existing membrane water treatment technologies based on nanofiltration, and further provides a two-stage low-drug self-regulating nanofiltration coupling system and its use method for concentrated water treatment. Technical Solutions

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] Technical solution 1: A two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment, including a raw water inlet tank, a waterfall aeration tower, a self-driven ecological membrane ultrafiltration, a nanofiltration inlet tank, a first-stage nanofiltration membrane assembly, a nanofiltration water production tank, an ion exchange membrane electrolysis reactor, a ceramic membrane assembly, an alkali solution storage tank, an acid solution storage tank, a nanofiltration concentrated water regulating tank, a second-stage nanofiltration membrane assembly and a salt water tank, wherein the raw water inlet tank, the self-driven ecological membrane ultrafiltration, the nanofiltration inlet tank, the first-stage nanofiltration membrane assembly and the nanofiltration water production tank are connected in sequence through pipelines The water production end of the second-stage nanofiltration membrane assembly is connected to the nanofiltration water production tank through a pipeline; the water production pipelines of the first-stage nanofiltration membrane assembly and the second-stage nanofiltration membrane assembly are also connected with a primary water discharge pipe; the concentrated water interface of the first-stage nanofiltration membrane assembly, the cathode chamber of the ion exchange membrane electrolysis reactor, the ceramic membrane assembly, the anode chamber of the ion exchange membrane electrolysis reactor, the nanofiltration concentrated water regulating box and the second-stage nanofiltration membrane assembly are connected in sequence through pipelines, and the concentrated water interface of the second-stage nanofiltration membrane assembly is connected with a second-stage nanofiltration concentrated water discharge pipe; the salt water tank The cathode chamber and the anode chamber of the ion exchange membrane electrolysis reactor are respectively connected through pipelines. The cathode chamber of the ion exchange membrane electrolysis reactor is connected to the alkali solution storage tank through a pipeline. The anode chamber of the ion exchange membrane electrolysis reactor is connected to the acid solution storage tank through a pipeline. The alkali solution storage tank and the acid solution storage tank are respectively connected to the input end of the cleaning pressure pump through pipelines. The output end of the cleaning pressure pump is respectively connected to the water inlet end of the first stage nanofiltration membrane assembly and the water inlet end of the second stage nanofiltration membrane assembly through pipelines. The concentrated water interface of the first stage nanofiltration membrane assembly is respectively connected to the alkali solution storage tank and the acid solution storage tank through pipelines. The concentrated water interface of the second stage nanofiltration membrane assembly is respectively connected to the alkali solution storage tank and the acid solution storage tank through pipelines. The alkali solution storage tank is connected to a cleaning alkali solution discharge pipe, and the acid solution storage tank is connected to a cleaning acid solution discharge pipe; a backwash pump is connected between the anode chamber of the ion exchange membrane electrolysis reactor and the water production end of the ceramic membrane assembly through a pipeline, and the water inlet end of the ceramic membrane assembly is connected to a backwash water discharge pipe; valves are set on each pipeline to control the pipeline connection.Technical solution 2: A two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment, including a water inlet tank, a waterfall aeration tower, a self-driven ecological membrane ultrafiltration, a nanofiltration water inlet tank, a first-stage nanofiltration membrane assembly, a nanofiltration water production tank, an ion exchange membrane electrolysis reactor, a ceramic membrane assembly, an alkali solution storage tank, an acid solution storage tank, a nanofiltration concentrated water regulating tank, a second-stage nanofiltration membrane assembly and a salt water tank, wherein the water inlet tank, the self-driven ecological membrane ultrafiltration, the nanofiltration water inlet tank, a first-stage nanofiltration membrane assembly and a nanofiltration water production tank are sequentially connected through pipelines. The water production end of the second-stage nanofiltration membrane assembly is connected to the nanofiltration water production tank through a pipeline; the water production pipelines of the first-stage nanofiltration membrane assembly and the second-stage nanofiltration membrane assembly are also connected with a primary water discharge pipe; the concentrated water interface of the first-stage nanofiltration membrane assembly, the cathode chamber of the ion exchange membrane electrolysis reactor, the ceramic membrane assembly, the anode chamber of the ion exchange membrane electrolysis reactor, the nanofiltration concentrated water regulating box and the second-stage nanofiltration membrane assembly are connected in sequence through pipelines, and the concentrated water interface of the second-stage nanofiltration membrane assembly is connected with the second-stage nanofiltration concentrated water Discharge pipe; the brine tank is connected to the cathode chamber and the anode chamber of the ion exchange membrane electrolysis reactor through pipelines, the cathode chamber of the ion exchange membrane electrolysis reactor is connected to the alkali solution storage tank through a pipeline, the anode chamber of the ion exchange membrane electrolysis reactor is connected to the acid solution storage tank through a pipeline, the alkali solution storage tank and the acid solution storage tank are connected to the input end of the cleaning pressure pump through pipelines, the output end of the cleaning pressure pump is connected to the water inlet end of the first stage nanofiltration membrane assembly, the water inlet end of the second stage nanofiltration membrane assembly and the water production end of the ceramic membrane assembly through pipelines, the concentrated water interface of the first stage nanofiltration membrane assembly is connected to the alkali solution storage tank and the acid solution storage tank through pipelines, the concentrated water interface of the second stage nanofiltration membrane assembly is connected to the alkali solution storage tank and the acid solution storage tank through pipelines, the water inlet end of the ceramic membrane assembly is connected to the alkali solution storage tank and the acid solution storage tank through pipelines, the alkali solution storage tank is connected to a cleaning alkali solution discharge pipe, and the acid solution storage tank is connected to a cleaning acid solution discharge pipe; valves are set on each pipeline to control the pipeline connection.

[0006] Furthermore, the driving pressure of the nanofiltration membrane is between 0.2 MPa and 0.4 MPa.

[0007] Furthermore, a micro-nano bubble aerator is provided in the ceramic membrane assembly.

[0008] Furthermore, a medium-pressure ultraviolet dechlorination device is connected to the connecting pipeline between the anode chamber of the ion exchange membrane electrolysis reactor and the acid storage tank.

[0009] Furthermore, the one-stage nanofiltration membrane assembly is a disc-tube nanofiltration membrane assembly.

[0010] Furthermore, the two-stage nanofiltration membrane assembly is a rolled nanofiltration membrane assembly.

[0011] Furthermore, an aeration tower inlet pump is provided on the connecting pipeline between the raw water inlet tank and the waterfall aeration tower, a first-stage nanofiltration inlet pump is provided on the connecting pipeline between the nanofiltration inlet tank and the first-stage nanofiltration membrane assembly, a second-stage nanofiltration inlet pump is provided on the connecting pipeline between the nanofiltration concentrate regulating tank and the second-stage nanofiltration membrane assembly, and an ion exchange membrane electrolysis inlet pump is provided on the connecting pipeline between the brine tank and the ion exchange membrane electrolysis reactor.

[0012] Technical Solution Three: A method for using the two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment described in the above-mentioned Technical Solution One, including a water production process, a concentrated water treatment process and a component cleaning process, wherein the water production process is: the raw water passes through the waterfall aeration tower, the self-driven ecological membrane ultrafiltration, a nanofiltration water inlet tank, and a nanofiltration membrane assembly in sequence from the water inlet tank to obtain nanofiltration produced water and nanofiltration concentrated water, wherein the nanofiltration produced water enters the nanofiltration produced water tank, and the nanofiltration concentrated water enters the concentrated water treatment process; the concentrated water treatment process is: step one, starting the ion exchange membrane electrolysis reactor: the nanofiltration concentrated water produced by the nanofiltration membrane assembly is input into the cathode chamber of the ion exchange membrane electrolysis reactor, and the anode chamber of the ion exchange membrane electrolysis reactor is injected with salt starting liquid, and the reactor is powered on; step two, the cathode chamber softens the concentrated water and removes organic matter: water electrolysis produces an alkaline environment, and calcium Magnesium forms particulate precipitation in an alkaline environment, the formed particulate matter adsorbs organic matter, and the resulting alkaline mixture enters the ceramic membrane assembly; Step three, discharge of salt starting liquid from the anode chamber: the salt starting liquid from the anode chamber of the ion exchange membrane electrolysis reactor is acidic after electrolysis and is discharged to the acid storage tank for storage; Step four, ceramic membrane separation of alkaline mixture from the cathode chamber: the alkaline mixture from the cathode chamber after electrolysis enters the ceramic membrane assembly, the ceramic membrane assembly intercepts the particulate matter, and the clear alkaline solution flows into the anode chamber of the ion exchange membrane electrolysis reactor; Step five, new concentrated water is injected into the cathode chamber: while the alkaline mixture from the cathode chamber after electrolysis flows into the ceramic membrane assembly, newly generated concentrated water is injected into the cathode chamber, and step two is repeated; Step six, oxidation of concentrated water in the anode chamber to adjust the pH: after electrolysis in the anode chamber, the clear alkaline solution removes part of the organic matter through oxidation, and adjusts the pH After adjusting back to neutral, it is discharged into the nanofiltration concentrated water regulating tank; Step seven, water production of the second-stage nanofiltration membrane assembly: the concentrated water pretreated in the nanofiltration concentrated water regulating tank enters the second-stage nanofiltration membrane assembly, and the produced water enters the nanofiltration water production tank to improve the system recovery rate; after startup, steps two, four to seven are repeated; the component cleaning process includes nanofiltration membrane component cleaning and ceramic membrane component cleaning: the nanofiltration membrane component cleaning includes the following steps: Step one, cleaning liquid generation: the water in the salt water tank flows into the cathode chamber and the anode chamber of the ion exchange membrane electrolysis reactor, and the acid and alkali liquids generated after electrolysis are discharged into the acid storage tank and the alkali storage tank respectively; Step two, low flow cleaning: use a cleaning pressure pump to replace the cleaning liquid with low pressure Raw water; Step 3, circulation: the cleaning liquid enters the nanofiltration membrane assembly from the raw water inlet and discharges from the concentrated water interface. At this time, the valves on the connecting pipeline between the first-stage nanofiltration membrane assembly and the nanofiltration water inlet tank and the valves on the connecting pipeline between the second-stage nanofiltration membrane assembly and the nanofiltration concentrated water regulating tank are all in the closed state. The cleaning liquid circulates back to the corresponding acid storage tank and alkali storage tank and ensures that the cleaning liquid temperature is constant; Step 4, soaking: stop the cleaning pressure pump and let the membrane element be completely immersed in the cleaning liquid; Step 5, high-flow cleaning: use high-flow circulating flushing liquid, and the pollutants are washed away by the cleaning liquid; Step 6, flushing: use pre-treated qualified produced water to flush the residual cleaning liquid in the nanofiltration system;Step 7. Restart the system: Restart the system after cleaning is completed; the cleaning of the ceramic membrane assembly includes the following steps: the acid liquid generated in the anode chamber of the ion exchange membrane electrolysis reactor enters the water production end of the ceramic membrane assembly after being pressurized by the backwash pump, and the backwash water of the ceramic membrane assembly is discharged through the backwash water discharge pipe. Technical Solution 4: A method for using the two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment described in the above-mentioned Technical Solution 4, including a water production process, a concentrated water treatment process and a component cleaning process, wherein the water production process is: the raw water passes through the waterfall aeration tower, the self-driven ecological membrane ultrafiltration, a nanofiltration water inlet tank, and a nanofiltration membrane assembly in sequence from the water inlet tank to obtain nanofiltration produced water and nanofiltration concentrated water, wherein the nanofiltration produced water enters the nanofiltration water production tank, and the nanofiltration concentrated water enters the concentrated water treatment process; the concentrated water treatment process is: step 1, starting the ion exchange membrane electrolysis reactor: the nanofiltration concentrated water produced by the nanofiltration membrane assembly is input into the cathode chamber of the ion exchange membrane electrolysis reactor, and the anode chamber of the ion exchange membrane electrolysis reactor is injected with salt starting liquid, and the reactor is powered on; step 2, the cathode chamber softens the concentrated water and removes organic matter: water electrolysis produces an alkaline environment, and calcium Magnesium forms particulate precipitation in an alkaline environment, the formed particulate matter adsorbs organic matter, and the resulting alkaline mixture enters the ceramic membrane assembly; Step three, discharge of salt starting liquid from the anode chamber: the salt starting liquid from the anode chamber of the ion exchange membrane electrolysis reactor is acidic after electrolysis and is discharged to the acid storage tank for storage; Step four, ceramic membrane separation of alkaline mixture from the cathode chamber: the alkaline mixture from the cathode chamber after electrolysis enters the ceramic membrane assembly, the ceramic membrane assembly intercepts the particulate matter, and the clear alkaline solution flows into the anode chamber of the ion exchange membrane electrolysis reactor; Step five, new concentrated water is injected into the cathode chamber: while the alkaline mixture from the cathode chamber after electrolysis flows into the ceramic membrane assembly, newly generated concentrated water is injected into the cathode chamber, and step two is repeated; Step six, oxidation of concentrated water in the anode chamber to adjust the pH: after electrolysis in the anode chamber, the clear alkaline solution removes part of the organic matter through oxidation, and adjusts the pH After adjusting back to neutral, it is discharged into the nanofiltration concentrated water regulating tank; Step seven, water production of the second-stage nanofiltration membrane assembly: the concentrated water pretreated in the nanofiltration concentrated water regulating tank enters the second-stage nanofiltration membrane assembly, and the produced water enters the nanofiltration water production tank to improve the system recovery rate; after startup, steps two, four to seven are repeated; the component cleaning process includes the following steps: Step one, cleaning liquid generation: the water in the salt water tank flows into the cathode chamber and the anode chamber of the ion exchange membrane electrolysis reactor, and the acid and alkali liquids generated after electrolysis are discharged into the acid storage tank and the alkali storage tank respectively; Step two, low flow cleaning: use a cleaning pressure pump to replace the raw water with a low cleaning liquid pressure;Step 3, circulation: For the nanofiltration membrane assembly, the cleaning liquid enters from the raw water inlet and discharges from the concentrated water interface. For the ceramic membrane assembly, the cleaning liquid enters from the water production end and discharges from the water inlet end. At this time, the valves on the connecting pipe between the first-stage nanofiltration membrane assembly and the nanofiltration water inlet tank, the valves on the connecting pipe between the second-stage nanofiltration membrane assembly and the nanofiltration concentrated water regulating tank, the valves on the connecting pipe between the ceramic membrane assembly and the cathode chamber, and the valves on the connecting pipe between the ceramic membrane assembly and the anode chamber are all in a closed state. The cleaning liquid circulates back to the corresponding acid and alkali storage tanks and ensures that the cleaning liquid temperature is constant; Step 4, soaking: stop the cleaning pressure pump and let the membrane element be completely immersed in the cleaning liquid; Step 5, high-flow cleaning: use high-flow circulating flushing liquid to flush away the pollutants; Step 6, flushing: use pre-treated qualified produced water to flush the residual cleaning liquid in the nanofiltration system; Step 7, restart the system: restart the system after cleaning is completed. Beneficial effects

[0013] Compared with the prior art, the present invention has the following effects:

[0014] This application improves the recovery rate of deep treatment of drinking water and effectively reduces secondary pollution caused by concentrated water discharge; by pre-configuring a certain concentration of salt solution and using an ion exchange membrane electrolysis device to generate acid and alkali solution, no other reagents need to be added, which effectively reduces the maintenance requirements of the nanofiltration system and reduces operating energy consumption; this application can self-detect and predict indicators, self-regulate and perform periodic cleaning without the addition of other reagents, and achieve a divalent salt removal rate of more than 60%, effectively reducing the maintenance requirements of the nanofiltration system and alleviating the difficulty of treating nanofiltration concentrated water. It has good environmental benefits and high economic benefits, and is suitable for village and town water supply and urban water supply with high concentrated water discharge requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG1 is a schematic diagram of a system flow chart of a specific embodiment 1 of the present application;

[0016] Figure 2 shows the salt removal effect of the system using the first embodiment. When the operating pressure of the nanofiltration membrane module is 0.2-0.4 MPa, Figure a) shows that the calcium ion removal rate is 60%-70%, and Figure b) shows that the sulfate removal rate in the influent is 65%-95%.

[0017] FIG3 is a schematic diagram of the system flow of the second specific implementation method in this application. Best Mode for Carrying Out the Invention

[0018] Specific embodiment 1: Combined with Figures 1-2, this embodiment is described, a two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment, including a raw water inlet tank 1, a waterfall aeration tower 2, a self-driven ecological membrane ultrafiltration 3, a nanofiltration inlet tank 4, a first-stage nanofiltration membrane assembly 5, a nanofiltration water production tank 6, an ion exchange membrane electrolysis reactor, a ceramic membrane assembly 9, an alkali solution storage tank 10, an acid solution storage tank 11, a nanofiltration concentrated water regulating tank 12, a second-stage nanofiltration membrane assembly 13 and a brine tank 14, wherein the raw water inlet tank 1, the self-driven ecological membrane ultrafiltration 3, the nanofiltration inlet tank 4, the first-stage nanofiltration membrane assembly 5 and the nanofiltration water production tank 6 are connected in sequence through pipelines, and the water production end of the second-stage nanofiltration membrane assembly 13 is connected to the nanofiltration water production tank 6 through a pipeline; the water production pipelines of the first-stage nanofiltration membrane assembly 5 and the second-stage nanofiltration membrane assembly 13 are also connected with a primary water discharge pipe 15; the first-stage nanofiltration membrane assembly 5 The concentrated water interface of the ion exchange membrane electrolysis reactor, the cathode chamber 7 of the ion exchange membrane electrolysis reactor, the ceramic membrane assembly 9, the anode chamber 8 of the ion exchange membrane electrolysis reactor, the nanofiltration concentrated water regulating box 12 and the second-stage nanofiltration membrane assembly 13 are connected in sequence through pipelines, and the concentrated water interface of the second-stage nanofiltration membrane assembly 13 is connected to the second-stage nanofiltration concentrated water discharge pipe 16; the brine tank 14 is connected to the cathode chamber 7 and the anode chamber 8 of the ion exchange membrane electrolysis reactor through pipelines, the cathode chamber 7 of the ion exchange membrane electrolysis reactor is connected to the alkali solution storage tank 10 through a pipeline, the anode chamber 8 of the ion exchange membrane electrolysis reactor is connected to the acid solution storage tank 11 through a pipeline, the alkali solution storage tank 10 and the acid solution storage tank 11 are respectively connected to the input end of the cleaning pressure pump 17 through pipelines, the output end of the cleaning pressure pump 17 is respectively connected to the water inlet end of the first-stage nanofiltration membrane assembly 5 and the water inlet end of the second-stage nanofiltration membrane assembly 13 through pipelines, the first-stage nanofiltration membrane assembly 5 The concentrated water interface of the second-stage nanofiltration membrane assembly 13 is connected to the alkali liquid storage tank 10 and the acid liquid storage tank 11 through pipelines, respectively. The concentrated water interface of the second-stage nanofiltration membrane assembly 13 is connected to the alkali liquid storage tank 10 and the acid liquid storage tank 11 through pipelines. The alkali liquid storage tank 10 is connected to a cleaning alkali liquid discharge pipe 18, and the acid liquid storage tank 11 is connected to a cleaning acid liquid discharge pipe 19; a backwash pump 20 is connected between the anode chamber 8 of the ion exchange membrane electrolysis reactor and the water production end of the ceramic membrane assembly 9 through a pipeline, and a backwash water discharge pipe 21 is connected to the water inlet end of the ceramic membrane assembly 9; valves are set on each pipeline to control the pipeline connection and disconnection.The filtration system is formed by sequentially connecting the raw water inlet tank 1, the waterfall aeration tower 2, the self-driven ecological membrane ultrafiltration 3, the nanofiltration inlet tank 4, the first-stage nanofiltration membrane assembly 5, and the produced water tank. The brine port of the first-stage nanofiltration membrane assembly 5, the cathode chamber 7 of the ion exchange membrane electrolysis reactor, the ceramic membrane assembly 9, the anode chamber 8 of the ion exchange membrane electrolysis reactor, the nanofiltration brine regulating tank 12, and the second-stage nanofiltration membrane assembly 13 are sequentially connected to form the brine treatment system. The component cleaning system is formed by the saline tank 14, the ion exchange membrane electrolysis reactor, the alkaline solution storage tank 10, and the acid solution storage tank 11. The component cleaning system performs chemical cleaning, such as alkaline or acid cleaning, on the first-stage nanofiltration membrane assembly 5, the second-stage nanofiltration membrane assembly 13, and the ceramic membrane assembly 9. The cleaning condition is that the normalized pressure difference between the inlet water and the brine increases by 15% or that the system has been in continuous operation for 3 to 5 months. The primary produced water discharge pipe 15 is provided with a primary produced water discharge valve 22. This design facilitates the separate discharge of primary water by providing a primary water discharge valve 22 and a primary water discharge pipe 15. After cleaning, the primary water is discharged for at least 10 minutes, or until the system is operating normally and the water is clear. A float valve 23 is connected to the drop aeration tower 2, which controls the water level within the drop aeration tower 2. The drop aeration tower 2 is preferably a slatted aeration tower with 4-6 slat layers and a clear spacing of 400mm to 600mm between layers, preferably 5 slat layers with a clear spacing of 500mm between layers. A first-stage pressure sensor 24 is installed on the connecting pipe between the nanofiltration inlet tank 4 and the first-stage nanofiltration membrane assembly 5, and a second-stage pressure sensor 25 is installed on the connecting pipe between the nanofiltration concentrate regulating tank 12 and the second-stage nanofiltration membrane assembly 13. Pressure changes within the first-stage nanofiltration membrane assembly 5 and the second-stage nanofiltration membrane assembly 13 are monitored by the first-stage pressure sensor 24 and the second-stage pressure sensor 25, respectively. Valves are installed on the connecting pipe between the nanofiltration inlet tank 4 and the first-stage nanofiltration membrane assembly 5, and on the connecting pipe between the nanofiltration concentrate regulating tank 12 and the second-stage nanofiltration membrane assembly 13 to control on / off.The concentrated water interface of the first-stage nanofiltration membrane assembly 5 is connected to the top of the cathode chamber 7 of the ion exchange membrane electrolysis reactor through a pipeline and a valve. The cathode chamber 7 of the ion exchange membrane electrolysis reactor and the anode chamber 8 of the ion exchange membrane electrolysis reactor are separated by an ion exchange membrane and an ion exchange membrane partition; the bottom of the cathode chamber 7 of the ion exchange membrane electrolysis reactor is connected to the water inlet side of the ceramic membrane assembly 9 through a pipeline and a valve; the water production side of the ceramic membrane assembly 9 is connected to the top of the anode chamber 8 of the ion exchange membrane electrolysis reactor through a pipeline and a valve; the bottom of the anode chamber 8 of the ion exchange membrane electrolysis reactor is connected to the top of the nanofiltration concentrated water regulating tank 12 through a pipeline and a valve; the water production pipeline of the first-stage nanofiltration membrane assembly 5 and the water production pipeline of the second-stage nanofiltration membrane assembly 13 are respectively connected to the water inlet pipeline of the nanofiltration water production tank 6, and valves are respectively provided on the water production pipeline of the first-stage nanofiltration membrane assembly 5, the water production pipeline of the second-stage nanofiltration membrane assembly 13 and the water inlet pipeline of the nanofiltration water production tank 6 to control the first-stage nanofiltration membrane assembly 5. The second-stage nanofiltration membrane assembly 13 is used to discharge produced water. A valve is installed on the outlet pipe of the brine tank 14 to facilitate water discharge control. The pipe between the cathode chamber 7 of the ion exchange membrane electrolysis reactor and the alkali storage tank 10 serves as an alkali channel, which is equipped with a valve. The pipe between the anode chamber 8 of the ion exchange membrane electrolysis reactor and the acid storage tank 11 serves as an acid channel, which is equipped with a valve. Cleaning control valves are installed on the connecting pipes between the alkali storage tank 10 and the cleaning pressure pump 17, between the acid storage tank 11 and the cleaning pressure pump 17, between the cleaning pressure pump 17 and the first-stage nanofiltration membrane assembly 5, and between the cleaning pressure pump 17 and the second-stage nanofiltration membrane assembly 13. Cleaning water is circulated from the concentrate port of the first-stage nanofiltration membrane assembly 5 and the concentrate port of the second-stage nanofiltration membrane assembly 13 to the alkali storage tank 10 and the acid storage tank 11, respectively. The cleaning alkali solution discharge pipe 18 and the cleaning acid solution discharge pipe 19 are used to discharge cleaning wastewater. Each of these is equipped with a cleaning solution discharge control valve. A backwash water discharge control valve is installed on the connecting pipe between the anode chamber 8 and the ceramic membrane assembly 9 of the ion exchange membrane electrolysis reactor to control the discharge of backwash water. Backwash water is discharged through the backwash water discharge pipe 21. The driving pressure of the nanofiltration membrane is between 0.2 MPa and 0.4 MPa. With this design, nanofiltration membrane technology can effectively remove a variety of pollutants from water, including organic matter and some inorganic pollutants. The driving pressure of the nanofiltration membrane is between 0.2 MPa and 0.4 MPa, enabling the nanofiltration membrane to operate in ultra-low pressure mode, causing the nanofiltration membrane contamination to undergo a morphological transformation. This effectively reduces the difficulty and frequency of cleaning, achieving water production standards while effectively reducing water production energy consumption.The self-driven ecological membrane ultrafiltration 3 uses the height difference between the waterfall aeration tower 2 and the self-driven ecological membrane ultrafiltration 3 to control the membrane filtration pressure. The membrane filtration pressure is 6 kPa, which is much lower than the traditional ultrafiltration process. The self-driven ecological membrane ultrafiltration 3 adopts a pore size of 0.03μm; the first-stage nanofiltration membrane component 5 preferably adopts an operating pressure of 0.2MPa-0.4MPa, preferably an operating pressure of 0.4MPa. At this time, the first-stage nanofiltration membrane component 5 has a sulfate removal rate of 60%~95% in the influent, and a calcium ion removal rate of 60%~70%; the ceramic membrane component 9 preferably adopts a membrane pore size of 0.05-0.5μm, preferably 0.2μm, which is a flat non-hollow membrane structure; the second-stage nanofiltration membrane component 13 preferably adopts an operating pressure of 0.2MPa-0.4MPa, preferably 0.4MPa; the ion exchange membrane electrolysis reactor electrolyzes salt water to produce acid and alkali solution, the pH of the acid solution is about 2, and the pH of the alkali solution is about 12. A micro-nano bubble aerator is installed in the ceramic membrane assembly 9. This design enhances the removal of inorganic particles from the membrane surface and enables air-water backwashing. A medium-pressure UV dechlorinator 26 is installed in the connecting pipeline between the anode chamber 8 of the ion exchange membrane electrolysis reactor and the acid storage tank 11. With this design, the acid generated in the anode chamber 8 of the ion exchange membrane electrolysis reactor is first treated by the medium-pressure UV dechlorinator 26 before being transported to the acid storage tank 11. The first-stage nanofiltration membrane assembly 5 is a disc-tube nanofiltration membrane assembly. The second-stage nanofiltration membrane assembly 13 is a spiral nanofiltration membrane assembly. An aeration tower inlet pump 27 is provided on the connecting pipeline between the raw water inlet tank 1 and the waterfall aeration tower 2, a first-stage nanofiltration inlet pump 28 is provided on the connecting pipeline between the nanofiltration inlet tank 4 and the first-stage nanofiltration membrane assembly 5, a second-stage nanofiltration inlet pump 29 is provided on the connecting pipeline between the nanofiltration concentrate regulating tank 12 and the second-stage nanofiltration membrane assembly 13, and an ion exchange membrane electrolysis inlet pump 30 is provided on the connecting pipeline between the brine tank 14 and the ion exchange membrane electrolysis reactor.

[0019] Specific embodiment 2: Combined with Figures 1-2, this embodiment is described. A method for using the two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment described in the above-mentioned specific embodiment 1 includes a water production process, a concentrated water treatment process and a component cleaning process, wherein the water production process is: raw water passes through the raw water inlet tank 1 in sequence through the waterfall aeration tower 2, the self-driven ecological membrane ultrafiltration 3, the nanofiltration water inlet tank 4, and a stage of nanofiltration membrane assembly 5 to obtain nanofiltration produced water and nanofiltration concentrated water, wherein the nanofiltration produced water enters the nanofiltration produced water tank 6, and the nanofiltration concentrated water enters the concentrated water treatment process; the raw water inlet tank 1 inputs incoming water, and the incoming water enters the waterfall aeration tower 2 for pretreatment to increase dissolved oxygen and provide sufficient conditions for removing pollutants such as Fe and Mn in the raw water; the effluent after pretreatment by the waterfall aeration tower 2 enters the self-driven ecological membrane ultrafiltration 3, and particulate matter, colloids, suspended matter and pathogenic microorganisms are intercepted, reducing the biodegradability of the raw water and reducing the pollution of the disc-tube nanofiltration membrane assembly, the self-driven ecological membrane ultrafiltration 3 The height difference between the waterfall aeration tower 2 and the self-driven ecological membrane ultrafiltration 3 is used to control the membrane filtration pressure. The self-driven ecological membrane ultrafiltration 3 can reduce the molecular weight of organic matter, and the dissolved organic matter can alleviate the formation of certain thorny crystals on the nanofiltration surface, thereby protecting the nanofiltration membrane; the effluent from the self-driven ecological membrane ultrafiltration 3 is stored in the nanofiltration water inlet tank 4, and then enters a nanofiltration membrane assembly 5; the concentrated water treatment process is as follows: Step 1, starting the ion exchange membrane electrolysis reactor: the nanofiltration concentrated water produced by the nanofiltration membrane assembly 5 is input into the cathode chamber 7 of the ion exchange membrane electrolysis reactor, and the anode chamber 8 of the ion exchange membrane electrolysis reactor is injected with salt starting liquid and powered on; Step 2, the cathode chamber 7 softens the concentrated water and removes organic matter: water electrolysis produces an alkaline environment, and calcium and magnesium form particulate precipitation in the alkaline environment. The formed particulate matter adsorbs organic matter, and the generated alkaline mixture enters the ceramic membrane assembly 9; under the condition of a current density of 25 A / m2, the pH value of the solution is 11.5.Step 3. Discharge of salt starting liquid from anode chamber 8: The salt starting liquid from anode chamber 8 of ion exchange membrane electrolysis reactor is acidic after electrolysis and is discharged to acid storage tank 11 for storage; Step 4. Ceramic membrane separation of alkaline mixture from cathode chamber 7: The alkaline mixture from cathode chamber 7 after electrolysis enters ceramic membrane assembly 9, which intercepts particulate matter, and clear alkaline solution flows into anode chamber 8 of ion exchange membrane electrolysis reactor; Step 5. Injection of new concentrated water into cathode chamber 7: While the alkaline mixture from cathode chamber 7 after electrolysis flows into ceramic membrane assembly 9, newly generated concentrated water is injected into cathode chamber 7, and step 2 is repeated; Step 6. Oxidation of concentrated water in anode chamber 8 to adjust pH: After electrolysis in anode chamber 8, the clear alkaline solution removes part of organic matter through oxidation, and the pH is adjusted back to neutral before being discharged into nanofiltration concentrated water regulating tank 12; Step 7. Water production from second-stage nanofiltration membrane assembly 13: Nanofiltration concentrated water regulating tank 12 The pretreated brine enters the secondary nanofiltration membrane assembly 13, and the produced water enters the nanofiltration product water tank 6, improving the system's recovery rate. A secondary nanofiltration brine regulating valve is installed on the secondary nanofiltration brine discharge pipe 16 to control the discharge of a small amount of brine. After startup, steps 2, 4, 5, and 7 are repeated. The component cleaning process includes cleaning the nanofiltration membrane assembly and the ceramic membrane assembly 9. The nanofiltration membrane assembly cleaning includes the following steps: Step 1: Cleaning Solution Generation: Water from the brine tank 14 flows into the cathode chamber 7 and anode chamber 8 of the ion exchange membrane electrolysis reactor. After electrolysis, the generated acid and alkali solutions are discharged into the acid solution storage tank 11 and alkali solution storage tank 10, respectively. The pH of the acidic cleaning is approximately 2, and the pH of the alkaline cleaning is approximately 12.Step 2, low flow cleaning: use the cleaning booster pump 17 to replace the raw water with a low cleaning liquid pressure; the cleaning pressure should be such that the control system does not produce obvious osmotic water production, the purpose is to replace the raw water in the component; the first stage nanofiltration membrane assembly 5 and the second stage nanofiltration membrane assembly 13 can be cleaned with acid or alkali solution, separately or simultaneously; during acid cleaning, close the nanofiltration membrane assembly cleaning control valve on the water suction line of the alkali solution storage tank 10, open the nanofiltration membrane assembly cleaning control valve on the water suction line of the acid solution storage tank 11, and the acid solution is pressurized by the cleaning booster pump 17 to control the nanofiltration membrane assembly cleaning control valve to flow into the first stage nanofiltration membrane assembly 5 and the second stage nanofiltration membrane assembly 13 separately or simultaneously, and input the cleaning liquid at a low flow rate; during alkali cleaning, close the nanofiltration membrane assembly cleaning control valve on the water suction line of the acid solution storage tank 11, open the nanofiltration membrane assembly cleaning control valve on the water suction line of the alkali solution storage tank 10, and the alkali solution is pressurized by the cleaning booster pump 17 to flow into the first stage nanofiltration membrane assembly 5 separately or simultaneously. The cleaning fluid is fed into the second-stage nanofiltration membrane assembly 13 at a low flow rate. Step 3: Circulation: The cleaning fluid enters the nanofiltration membrane assembly from the raw water inlet and exits from the concentrate port. At this point, the valves on the connecting pipelines between the first-stage nanofiltration membrane assembly 5 and the nanofiltration inlet tank 4, as well as the valves on the connecting pipelines between the second-stage nanofiltration membrane assembly 13 and the nanofiltration concentrate regulating tank 12, are closed. The cleaning fluid circulates back to the corresponding acid storage tank 11 and alkali storage tank 10, ensuring a constant cleaning fluid temperature. This circulation process lasts for 30 minutes. Step 4: Soaking: Stop the cleaning booster pump 17 and allow the membrane elements to completely immerse in the cleaning fluid. This soaking process lasts for at least 1 hour. Step 5: High-flow Cleaning: A high-flow circulating flushing fluid is used to flush away contaminants. The high-flow pump circulation process lasts for 30-60 minutes. Step 6: Rinse: Use pretreated, qualified product water to flush any remaining cleaning fluid from the nanofiltration system. This rinse process lasts for 30 minutes. Step 7: Restart the system: After cleaning is complete, restart the system. The initial water produced after restart cannot be discharged into the nanofiltration water tank 6. A separate initial water discharge valve 22 and pipeline are installed. The acid and alkali solution storage tank 10 is equipped with a cleaning alkali solution discharge control valve and a cleaning acid solution discharge control valve to discharge cleaning wastewater. Cleaning the ceramic membrane assembly 9 includes the following steps: the acid produced by the anode chamber 8 of the ion exchange membrane electrolysis reactor is pressurized by the backwash pump 20 and enters the water production end of the ceramic membrane assembly 9. The backwash water of the ceramic membrane assembly 9 is discharged through the backwash water discharge pipe 21. The nanofiltration concentrate produced by the first stage nanofiltration membrane assembly 5 of the nanofiltration concentrate treatment system, the nanofiltration chemical cleaning wastewater produced by the module cleaning system, the backwash water of the ceramic membrane assembly 9, and / or the initial water produced after restart are discharged into the main wastewater pipe in a certain proportion. The wastewater must meet the requirements of the "Integrated Wastewater Discharge Standard" (GB 8978). The driving pressure of the nanofiltration membrane is between 0.2MPa and 0.4MPa.With this design, nanofiltration membrane technology can effectively remove a variety of pollutants in water, including organic matter and some inorganic pollutants. The driving pressure of the nanofiltration membrane is between 0.2MPa-0.4MPa, which enables the nanofiltration membrane to operate in ultra-low pressure mode, causing the nanofiltration membrane pollution to undergo a morphological change, thereby effectively reducing the difficulty of cleaning, reducing the frequency of cleaning, and effectively reducing the energy consumption of water production while meeting the water production standards. The self-driven ecological membrane ultrafiltration 3 uses the height difference between the waterfall aeration tower 2 and the self-driven ecological membrane ultrafiltration 3 to control the membrane filtration pressure. The membrane filtration pressure is 6 kPa, which is much lower than the traditional ultrafiltration process. The self-driven ecological membrane ultrafiltration 3 adopts a pore size of 0.03μm; the first-stage nanofiltration membrane component 5 preferably adopts an operating pressure of 0.2MPa-0.4MPa, preferably an operating pressure of 0.4MPa. At this time, the first-stage nanofiltration membrane component 5 has a sulfate removal rate of 60%~95% in the influent, and a calcium ion removal rate of 60%~70%; the ceramic membrane component 9 preferably adopts a membrane pore size of 0.05-0.5μm, preferably 0.2μm, which is a flat non-hollow membrane structure; the second-stage nanofiltration membrane component 13 preferably adopts an operating pressure of 0.2MPa-0.4MPa, preferably 0.4MPa; the ion exchange membrane electrolysis reactor electrolyzes salt water to produce acid and alkali solution, the pH of the acid solution is about 2, and the pH of the alkali solution is about 12. A micro-nano bubble aerator is installed in the ceramic membrane assembly 9. This design enhances the removal of inorganic particles from the membrane surface and enables air-water backwashing. A medium-pressure UV dechlorinator 26 is installed in the connecting pipeline between the anode chamber 8 of the ion exchange membrane electrolysis reactor and the acid storage tank 11. With this design, the acid generated in the anode chamber 8 of the ion exchange membrane electrolysis reactor is first treated by the medium-pressure UV dechlorinator 26 before being transported to the acid storage tank 11. The first-stage nanofiltration membrane assembly 5 is a disc-tube nanofiltration membrane assembly. The second-stage nanofiltration membrane assembly 13 is a spiral nanofiltration membrane assembly. The connecting pipeline between the raw water inlet tank 1 and the waterfall aeration tower 2 is equipped with an aeration tower inlet pump 27. The connecting pipeline between the nanofiltration inlet tank 4 and the first-stage nanofiltration membrane assembly 5 is equipped with a first-stage nanofiltration inlet pump 28. The connecting pipeline between the nanofiltration concentrate regulating tank 12 and the second-stage nanofiltration membrane assembly 13 is equipped with a second-stage nanofiltration inlet pump 29. The connecting pipeline between the brine tank 14 and the ion exchange membrane electrolysis reactor is equipped with an ion exchange membrane electrolysis inlet pump 30. Other components and connections are the same as those in the first embodiment.

[0020] Specific embodiment three: Combined with Figures 2-3, this embodiment is described, a two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment, including a raw water inlet tank 1, a waterfall aeration tower 2, a self-driven ecological membrane ultrafiltration 3, a nanofiltration inlet tank 4, a first-stage nanofiltration membrane assembly 5, a nanofiltration water production tank 6, an ion exchange membrane electrolysis reactor, a ceramic membrane assembly 9, an alkali solution storage tank 10, an acid solution storage tank 11, a nanofiltration concentrated water regulating tank 12, a second-stage nanofiltration membrane assembly 13 and a brine tank 14, wherein the raw water inlet tank 1, the self-driven ecological membrane ultrafiltration 3, the nanofiltration inlet tank 4, the first-stage nanofiltration membrane assembly 5 and the nanofiltration water production tank 6 are connected in sequence through pipelines, and the water production end of the second-stage nanofiltration membrane assembly 13 is connected to the nanofiltration water production tank 6 through a pipeline; the water production pipelines of the first-stage nanofiltration membrane assembly 5 and the second-stage nanofiltration membrane assembly 13 are also connected with a primary water discharge pipe 15; the first-stage nanofiltration membrane assembly 5 The concentrated water interface of the ion exchange membrane electrolysis reactor, the cathode chamber 7 of the ion exchange membrane electrolysis reactor, the ceramic membrane assembly 9, the anode chamber 8 of the ion exchange membrane electrolysis reactor, the nanofiltration concentrated water regulating box 12 and the second-stage nanofiltration membrane assembly 13 are connected in sequence through pipelines, and the concentrated water interface of the second-stage nanofiltration membrane assembly 13 is connected to the second-stage nanofiltration concentrated water discharge pipe 16; the brine tank 14 is connected to the cathode chamber 7 and the anode chamber 8 of the ion exchange membrane electrolysis reactor through pipelines, the cathode chamber 7 of the ion exchange membrane electrolysis reactor is connected to the alkali solution storage tank 10 through a pipeline, the anode chamber 8 of the ion exchange membrane electrolysis reactor is connected to the acid solution storage tank 11 through a pipeline, the alkali solution storage tank 10 and the acid solution storage tank 11 are respectively connected to the input end of the cleaning pressure pump 17 through pipelines, and the output end of the cleaning pressure pump 17 is respectively connected to the water inlet end of the first-stage nanofiltration membrane assembly 5, the water inlet end of the second-stage nanofiltration membrane assembly 13 and the water production end of the ceramic membrane assembly 9 through pipelines, the first-stage nanofiltration membrane assembly 5 The concentrated water interface of the second-stage nanofiltration membrane assembly 13 is connected to the alkali liquid storage tank 10 and the acid liquid storage tank 11 through pipelines, respectively. The concentrated water interface of the second-stage nanofiltration membrane assembly 13 is connected to the alkali liquid storage tank 10 and the acid liquid storage tank 11 through pipelines, respectively. The water inlet end of the ceramic membrane assembly 9 is connected to the alkali liquid storage tank 10 and the acid liquid storage tank 11 through pipelines, respectively. The alkali liquid storage tank 10 is connected to a cleaning alkali liquid discharge pipe 18, and the acid liquid storage tank 11 is connected to a cleaning acid liquid discharge pipe 19; valves are set on each pipeline to control the pipeline connection and disconnection.The filtration system is formed by sequentially connecting the raw water inlet tank 1, the waterfall aeration tower 2, the self-driven ecological membrane ultrafiltration 3, the nanofiltration inlet tank 4, the first-stage nanofiltration membrane assembly 5, and the produced water tank. The brine port of the first-stage nanofiltration membrane assembly 5, the cathode chamber 7 of the ion exchange membrane electrolysis reactor, the ceramic membrane assembly 9, the anode chamber 8 of the ion exchange membrane electrolysis reactor, the nanofiltration brine regulating tank 12, and the second-stage nanofiltration membrane assembly 13 are sequentially connected to form the brine treatment system. The component cleaning system is formed by the saline tank 14, the ion exchange membrane electrolysis reactor, the alkaline solution storage tank 10, and the acid solution storage tank 11. The component cleaning system performs chemical cleaning, such as alkaline or acid cleaning, on the first-stage nanofiltration membrane assembly 5, the second-stage nanofiltration membrane assembly 13, and the ceramic membrane assembly 9. The cleaning condition is a 15% increase in the standardized pressure difference between the inlet water and the brine or a continuous operation period of 3 to 5 months. The primary produced water discharge pipe 15 is provided with a primary produced water discharge valve 22. This design facilitates the separate discharge of primary water by providing a primary water discharge valve 22 and a primary water discharge pipe 15. After cleaning, the primary water is discharged for at least 10 minutes, or until the system is operating normally and the water is clear. A float valve 23 is connected to the drop aeration tower 2, which controls the water level within the drop aeration tower 2. The drop aeration tower 2 is preferably a slatted aeration tower with 4-6 slat layers and a clear spacing of 400mm to 600mm between layers, preferably 5 slat layers with a clear spacing of 500mm between layers. A first-stage pressure sensor 24 is installed on the connecting pipe between the nanofiltration inlet tank 4 and the first-stage nanofiltration membrane assembly 5, and a second-stage pressure sensor 25 is installed on the connecting pipe between the nanofiltration concentrate regulating tank 12 and the second-stage nanofiltration membrane assembly 13. Pressure changes within the first-stage nanofiltration membrane assembly 5 and the second-stage nanofiltration membrane assembly 13 are monitored by the first-stage pressure sensor 24 and the second-stage pressure sensor 25, respectively. Valves are installed on the connecting pipe between the nanofiltration inlet tank 4 and the first-stage nanofiltration membrane assembly 5, and on the connecting pipe between the nanofiltration concentrate regulating tank 12 and the second-stage nanofiltration membrane assembly 13 to control on / off.The concentrated water interface of the first-stage nanofiltration membrane assembly 5 is connected to the top of the cathode chamber 7 of the ion exchange membrane electrolysis reactor through a pipeline and a valve. The cathode chamber 7 of the ion exchange membrane electrolysis reactor and the anode chamber 8 of the ion exchange membrane electrolysis reactor are separated by an ion exchange membrane and an ion exchange membrane partition; the bottom of the cathode chamber 7 of the ion exchange membrane electrolysis reactor is connected to the water inlet side of the ceramic membrane assembly 9 through a pipeline and a valve; the water production side of the ceramic membrane assembly 9 is connected to the top of the anode chamber 8 of the ion exchange membrane electrolysis reactor through a pipeline and a valve; the bottom of the anode chamber 8 of the ion exchange membrane electrolysis reactor is connected to the top of the nanofiltration concentrated water regulating tank 12 through a pipeline and a valve; the water production pipeline of the first-stage nanofiltration membrane assembly 5 and the water production pipeline of the second-stage nanofiltration membrane assembly 13 are respectively connected to the water inlet pipeline of the nanofiltration water production tank 6, and valves are respectively provided on the water production pipeline of the first-stage nanofiltration membrane assembly 5, the water production pipeline of the second-stage nanofiltration membrane assembly 13 and the water inlet pipeline of the nanofiltration water production tank 6 to control the first-stage nanofiltration membrane assembly 5. The water produced by the second-stage nanofiltration membrane assembly 13 is discharged. A valve is installed on the outlet pipe of the brine tank 14 to facilitate water discharge from the brine tank 14. The pipe between the cathode chamber 7 of the ion exchange membrane electrolysis reactor and the alkali liquid storage tank 10 serves as an alkali liquid channel, which is equipped with a valve. The pipe between the anode chamber 8 of the ion exchange membrane electrolysis reactor and the acid liquid storage tank 11 serves as an acid liquid channel, which is equipped with a valve. Cleaning control valves are installed on the connecting pipes between the alkali liquid storage tank 10 and the cleaning pressure pump 17, between the acid liquid storage tank 11 and the cleaning pressure pump 17, between the cleaning pressure pump 17 and the first-stage nanofiltration membrane assembly 5, between the cleaning pressure pump 17 and the second-stage nanofiltration membrane assembly 13, and between the cleaning pressure pump 17 and the ceramic membrane assembly 9. Wash water is circulated from the concentrate port of the first-stage nanofiltration membrane assembly 5, the concentrate port of the second-stage nanofiltration membrane assembly 13, and the water inlet of the ceramic membrane assembly 9 to the alkali solution storage tank 10 and the acid solution storage tank 11, respectively. The wash alkali solution discharge pipe 18 and the wash acid solution discharge pipe 19 are used to discharge the wash wastewater. Each of these pipes is equipped with a wash liquid discharge control valve. In this embodiment, the first-stage nanofiltration membrane assembly 5, the second-stage nanofiltration membrane assembly 13, and the ceramic membrane assembly 9 share a common set of wash piping. The wash liquid for the first-stage nanofiltration membrane assembly 5 and the second-stage nanofiltration membrane assembly 13 enters the assembly from the raw water port and exits from the concentrate port. The wash liquid for the ceramic membrane assembly 9 enters from the product water port and exits from the water inlet port. The driving pressure of the nanofiltration membrane is between 0.2 MPa and 0.4 MPa.With this design, nanofiltration membrane technology can effectively remove a variety of pollutants in water, including organic matter and some inorganic pollutants. The driving pressure of the nanofiltration membrane is between 0.2MPa-0.4MPa, which enables the nanofiltration membrane to operate in ultra-low pressure mode, causing the nanofiltration membrane pollution to undergo a morphological change, thereby effectively reducing the difficulty of cleaning, reducing the frequency of cleaning, and effectively reducing the energy consumption of water production while meeting the water production standards. The self-driven ecological membrane ultrafiltration 3 uses the height difference between the waterfall aeration tower 2 and the self-driven ecological membrane ultrafiltration 3 to control the membrane filtration pressure. The membrane filtration pressure is 6 kPa, which is much lower than the traditional ultrafiltration process. The self-driven ecological membrane ultrafiltration 3 adopts a pore size of 0.03μm; the first-stage nanofiltration membrane component 5 preferably adopts an operating pressure of 0.2MPa-0.4MPa, preferably an operating pressure of 0.4MPa. At this time, the first-stage nanofiltration membrane component 5 has a sulfate removal rate of 60%~95% in the influent, and a calcium ion removal rate of 60%~70%; the ceramic membrane component 9 preferably adopts a membrane pore size of 0.05-0.5μm, preferably 0.2μm, which is a flat non-hollow membrane structure; the second-stage nanofiltration membrane component 13 preferably adopts an operating pressure of 0.2MPa-0.4MPa, preferably 0.4MPa; the ion exchange membrane electrolysis reactor electrolyzes salt water to produce acid and alkali solution, the pH of the acid solution is about 2, and the pH of the alkali solution is about 12. A micro-nano bubble aerator is installed in the ceramic membrane assembly 9. This design enhances the removal of inorganic particles from the membrane surface and enables air-water backwashing. A medium-pressure UV dechlorinator 26 is installed in the connecting pipeline between the anode chamber 8 of the ion exchange membrane electrolysis reactor and the acid storage tank 11. With this design, the acid generated in the anode chamber 8 of the ion exchange membrane electrolysis reactor is first treated by the medium-pressure UV dechlorinator 26 before being transported to the acid storage tank 11. The first-stage nanofiltration membrane assembly 5 is a disc-tube nanofiltration membrane assembly. The second-stage nanofiltration membrane assembly 13 is a spiral nanofiltration membrane assembly. An aeration tower inlet pump 27 is provided on the connecting pipeline between the raw water inlet tank 1 and the waterfall aeration tower 2, a first-stage nanofiltration inlet pump 28 is provided on the connecting pipeline between the nanofiltration inlet tank 4 and the first-stage nanofiltration membrane assembly 5, a second-stage nanofiltration inlet pump 29 is provided on the connecting pipeline between the nanofiltration concentrate regulating tank 12 and the second-stage nanofiltration membrane assembly 13, and an ion exchange membrane electrolysis inlet pump 30 is provided on the connecting pipeline between the brine tank 14 and the ion exchange membrane electrolysis reactor.

[0021] Specific embodiment four: Combined with Figures 2-3, this embodiment is described. A method for using the two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment described in the above specific embodiment three includes a water production process, a concentrated water treatment process and a component cleaning process, wherein the water production process is: raw water passes through the raw water inlet tank 1 in sequence through the waterfall aeration tower 2, the self-driven ecological membrane ultrafiltration 3, the nanofiltration water inlet tank 4, and a stage of nanofiltration membrane assembly 5 to obtain nanofiltration produced water and nanofiltration concentrated water, wherein the nanofiltration produced water enters the nanofiltration produced water tank 6, and the nanofiltration concentrated water enters the concentrated water treatment process; the raw water inlet tank 1 inputs incoming water, and the incoming water enters the waterfall aeration tower 2 for pretreatment to increase dissolved oxygen and provide sufficient conditions for removing pollutants such as Fe and Mn in the raw water; the effluent after pretreatment by the waterfall aeration tower 2 enters the self-driven ecological membrane ultrafiltration 3, and particulate matter, colloids, suspended matter and pathogenic microorganisms are intercepted, reducing the biodegradability of the raw water and reducing the pollution of the disc-tube nanofiltration membrane assembly, the self-driven ecological membrane ultrafiltration 3 The height difference between the waterfall aeration tower 2 and the self-driven ecological membrane ultrafiltration 3 is used to control the membrane filtration pressure. The self-driven ecological membrane ultrafiltration 3 can reduce the molecular weight of organic matter, and the dissolved organic matter can alleviate the formation of certain thorny crystals on the nanofiltration surface, thereby protecting the nanofiltration membrane; the effluent from the self-driven ecological membrane ultrafiltration 3 is stored in the nanofiltration water inlet tank 4, and then enters a nanofiltration membrane assembly 5; the concentrated water treatment process is as follows: Step 1, starting the ion exchange membrane electrolysis reactor: the nanofiltration concentrated water produced by the nanofiltration membrane assembly 5 is input into the cathode chamber 7 of the ion exchange membrane electrolysis reactor, and the anode chamber 8 of the ion exchange membrane electrolysis reactor is injected with salt starting liquid and powered on; Step 2, the cathode chamber 7 softens the concentrated water and removes organic matter: water electrolysis produces an alkaline environment, and calcium and magnesium form particulate precipitation in the alkaline environment. The formed particulate matter adsorbs organic matter, and the generated alkaline mixture enters the ceramic membrane assembly 9; under the condition of a current density of 25 A / m2, the pH value of the solution is 11.5.Step 3. Discharge of salt starting liquid from anode chamber 8: The salt starting liquid from anode chamber 8 of ion exchange membrane electrolysis reactor is acidic after electrolysis and is discharged to acid storage tank 11 for storage; Step 4. Ceramic membrane separation of alkaline mixture from cathode chamber 7: The alkaline mixture from cathode chamber 7 after electrolysis enters ceramic membrane assembly 9, which intercepts particulate matter, and clear alkaline solution flows into anode chamber 8 of ion exchange membrane electrolysis reactor; Step 5. Injection of new concentrated water into cathode chamber 7: While the alkaline mixture from cathode chamber 7 after electrolysis flows into ceramic membrane assembly 9, newly generated concentrated water is injected into cathode chamber 7, and step 2 is repeated; Step 6. Oxidation of concentrated water in anode chamber 8 to adjust pH: After electrolysis in anode chamber 8, the clear alkaline solution removes part of organic matter through oxidation, and the pH is adjusted back to neutral before being discharged into nanofiltration concentrated water regulating tank 12; Step 7. Water production from second-stage nanofiltration membrane assembly 13: Nanofiltration concentrated water regulating tank 12 The pretreated brine enters the secondary nanofiltration membrane assembly 13, and the produced water enters the nanofiltration product water tank 6, improving the system's recovery rate. A secondary nanofiltration brine regulating valve is installed on the secondary nanofiltration brine discharge pipe 16 to control the discharge of a small amount of brine. After startup, steps 2, 4, 5, and 7 are repeated. The component cleaning process includes the following steps: Step 1: Cleaning Liquid Generation: Water from the brine tank 14 flows into the cathode chamber 7 and anode chamber 8 of the ion exchange membrane electrolysis reactor. After electrolysis, the generated acid and alkali solutions are discharged into the acid and alkali storage tanks 11 and 10, respectively. The pH of the acidic cleaning is approximately 2, and the pH of the alkaline cleaning is approximately 12.Step 2, low flow cleaning: use the cleaning pressure pump 17 to replace the raw water with a low cleaning liquid pressure; the cleaning pressure should be such that the control system does not produce obvious permeation water production, the purpose is to replace the raw water in the component; the first stage nanofiltration membrane assembly 5, the second stage nanofiltration membrane assembly 13 and the ceramic membrane assembly 9 can be cleaned with acid or alkali solution, separately or simultaneously; during acid cleaning, close the nanofiltration membrane assembly cleaning control valve on the water suction line of the alkali solution storage tank 10, open the nanofiltration membrane assembly cleaning control valve on the water suction line of the acid solution storage tank 11, and the acid is pressurized by the cleaning pressure pump 17 to control the nanofiltration membrane assembly cleaning control valve to flow into the first stage nanofiltration membrane assembly 5, the second stage nanofiltration membrane assembly 13 and the ceramic membrane assembly 9 separately or simultaneously, and input the cleaning liquid at a low flow rate; during alkali cleaning, close the nanofiltration membrane assembly cleaning control valve on the water suction line of the acid solution storage tank 11, open the nanofiltration membrane assembly cleaning control valve on the water suction line of the alkali solution storage tank 10, and the alkali solution passes through the cleaning pressure pump 17. Under pressure, the cleaning liquid flows individually or simultaneously into the first-stage nanofiltration membrane assembly 5, the second-stage nanofiltration membrane assembly 13, and the ceramic membrane assembly 9, with a low flow rate of cleaning liquid. Step 3: Circulation: For the nanofiltration membrane assembly, the cleaning liquid enters from the raw water inlet and exits from the concentrate port. For the ceramic membrane assembly 9, the cleaning liquid enters from the produced water end and exits from the water inlet. At this time, the valves on the connecting pipeline between the first-stage nanofiltration membrane assembly 5 and the nanofiltration inlet tank 4, the valves on the connecting pipeline between the second-stage nanofiltration membrane assembly 13 and the nanofiltration concentrate regulating tank 12, the valves on the connecting pipeline between the ceramic membrane assembly 9 and the cathode chamber 7, and the valves on the connecting pipeline between the ceramic membrane assembly 9 and the anode chamber 8 are all closed. The cleaning liquid circulates back to the corresponding acid and alkali storage tanks 11 and 10, ensuring a constant cleaning liquid temperature. This circulation process lasts for 30 minutes. Step 4: Soaking: Stop the cleaning pressure pump 17 and allow the membrane elements to be completely immersed in the cleaning liquid. This soaking process lasts for at least 1 hour. Step 5, High-Flow Cleaning: Use a high-flow circulating flushing fluid to flush away contaminants. The high-flow pump circulation process lasts for 30-60 minutes. Step 6, Rinsing: Use pre-treated, qualified produced water to flush any remaining cleaning fluid from the nanofiltration system. The flushing process lasts for 30 minutes. Step 7, Restarting the System: After cleaning, restart the system. The initial produced water after restart cannot be discharged into the nanofiltration produced water tank 6. A separate primary produced water discharge valve 22 and pipeline are provided. The acid and alkali solution storage tank 10 is equipped with a cleaning alkali solution discharge control valve and a cleaning acid solution discharge control valve to discharge cleaning wastewater. The nanofiltration brine produced by the first stage nanofiltration membrane module 5 in the nanofiltration brine treatment system, the nanofiltration chemical cleaning wastewater produced by the module cleaning system, the backwash water from the ceramic membrane module 9, and / or the initial produced water after restart are discharged into the main wastewater pipe in a certain proportion. This wastewater must meet the requirements of the "Comprehensive Wastewater Discharge Standard" (GB 8978).

Claims

1. A two-stage low-drug self-regulating nanofiltration coupling system for concentrated water treatment, characterized in that: The invention comprises a raw water inlet tank (1), a waterfall aeration tower (2), a self-driven ecological membrane ultrafiltration (3), a nanofiltration inlet tank (4), a first-stage nanofiltration membrane assembly (5), a nanofiltration water production tank (6), an ion exchange membrane electrolysis reactor, a ceramic membrane assembly (9), an alkali solution storage tank (10), an acid solution storage tank (11), a nanofiltration concentrated water regulating tank (12), a second-stage nanofiltration membrane assembly (13) and a salt water tank (14), wherein the raw water inlet tank (1), the self-driven ecological membrane ultrafiltration (3), the nanofiltration inlet tank (4), the first-stage nanofiltration membrane assembly (5) and the nanofiltration water production tank (6) are sequentially connected through pipelines, and the water production of the second-stage nanofiltration membrane assembly (13) is The first end is connected to the nanofiltration water production tank (6) through a pipeline; the water production pipelines of the first nanofiltration membrane assembly (5) and the second nanofiltration membrane assembly (13) are also connected to a primary water discharge pipe (15); the concentrated water interface of the first nanofiltration membrane assembly (5), the cathode chamber (7) of the ion exchange membrane electrolysis reactor, the ceramic membrane assembly (9), the anode chamber (8) of the ion exchange membrane electrolysis reactor, the nanofiltration concentrated water regulating box (12) and the second nanofiltration membrane assembly (13) are connected in sequence through pipelines, and the concentrated water interface of the second nanofiltration membrane assembly (13) is connected to a second nanofiltration concentrated water discharge pipe (16); the salt water tank (14) is connected to the ion exchange membrane electrolysis reactor through pipelines. The cathode chamber (7) and the anode chamber (8) of the ion exchange membrane electrolysis reactor are connected to the alkali solution storage tank (10) through a pipeline, and the anode chamber (8) of the ion exchange membrane electrolysis reactor is connected to the acid solution storage tank (11) through a pipeline. The alkali solution storage tank (10) and the acid solution storage tank (11) are respectively connected to the input end of the cleaning pressure pump (17) through pipelines. The output end of the cleaning pressure pump (17) is respectively connected to the water inlet end of the first stage nanofiltration membrane assembly (5) and the water inlet end of the second stage nanofiltration membrane assembly (13) through pipelines. The concentrated water interface of the first stage nanofiltration membrane assembly (5) is respectively connected to the alkali solution storage tank (10) and the acid solution storage tank (11) through pipelines. A liquid storage tank (10) and an acid storage tank (11); the concentrated water interface of the second-stage nanofiltration membrane assembly (13) is connected to the alkali storage tank (10) and the acid storage tank (11) through pipelines, respectively; the alkali storage tank (10) is connected to a cleaning alkali liquid discharge pipe (18), and the acid storage tank (11) is connected to a cleaning acid liquid discharge pipe (19); a backwashing pump (20) is connected between the anode chamber (8) of the ion exchange membrane electrolysis reactor and the water production end of the ceramic membrane assembly (9) through a pipeline, and a backwashing water discharge pipe (21) is connected to the water inlet end of the ceramic membrane assembly (9); and valves are provided on each pipeline to control the on-off of the pipeline.

2. A two-stage concentrated water treatment system with low-drug self-regulating nanofiltration coupling, characterized in that: The invention comprises a raw water inlet tank (1), a waterfall aeration tower (2), a self-driven ecological membrane ultrafiltration (3), a nanofiltration inlet tank (4), a first-stage nanofiltration membrane assembly (5), a nanofiltration water production tank (6), an ion exchange membrane electrolysis reactor, a ceramic membrane assembly (9), an alkali solution storage tank (10), an acid solution storage tank (11), a nanofiltration concentrated water regulating tank (12), a second-stage nanofiltration membrane assembly (13) and a salt water tank (14), wherein the raw water inlet tank (1), the self-driven ecological membrane ultrafiltration (3), the nanofiltration inlet tank (4), the first-stage nanofiltration membrane assembly (5) and the nanofiltration water production tank (6) are sequentially connected through pipelines, and the second-stage nanofiltration membrane assembly (11) is connected to the nanofiltration membrane assembly (12). The water production end of the first-stage nanofiltration membrane assembly (5) and the second-stage nanofiltration membrane assembly (13) is connected to the nanofiltration water production tank (6) through a pipeline; the water production pipelines of the first-stage nanofiltration membrane assembly (5) and the second-stage nanofiltration membrane assembly (13) are also connected to a primary water discharge pipe (15); the concentrated water interface of the first-stage nanofiltration membrane assembly (5), the cathode chamber (7) of the ion exchange membrane electrolysis reactor, the anode chamber (8) of the ceramic membrane assembly (9) and the ion exchange membrane electrolysis reactor, the nanofiltration concentrated water regulating box (12) and the second-stage nanofiltration membrane assembly (13) are connected in sequence through pipelines, and the concentrated water interface of the second-stage nanofiltration membrane assembly (13) is connected to a second-stage nanofiltration concentrated water discharge pipe (16); the salt water tank (14) The cathode chamber (7) and the anode chamber (8) of the ion exchange membrane electrolysis reactor are connected to each other through pipelines. The cathode chamber (7) of the ion exchange membrane electrolysis reactor is connected to the alkali solution storage tank (10) through pipelines. The anode chamber (8) of the ion exchange membrane electrolysis reactor is connected to the acid solution storage tank (11) through pipelines. The alkali solution storage tank (10) and the acid solution storage tank (11) are connected to the input end of the cleaning pressure pump (17) through pipelines. The output end of the cleaning pressure pump (17) is connected to the water inlet end of the first stage nanofiltration membrane assembly (5), the water inlet end of the second stage nanofiltration membrane assembly (13) and the ceramic membrane assembly (9) through pipelines. ), the concentrated water interface of the first stage nanofiltration membrane assembly (5) is connected to the alkali liquid storage tank (10) and the acid liquid storage tank (11) through pipelines, respectively; the concentrated water interface of the second stage nanofiltration membrane assembly (13) is connected to the alkali liquid storage tank (10) and the acid liquid storage tank (11) through pipelines, respectively; the water inlet end of the ceramic membrane assembly (9) is connected to the alkali liquid storage tank (10) and the acid liquid storage tank (11) through pipelines, respectively; the alkali liquid storage tank (10) is connected to a cleaning alkali liquid discharge pipe (18), and the acid liquid storage tank (11) is connected to a cleaning acid liquid discharge pipe (19); valves are provided on each pipeline to control the on-off of the pipeline.

3. The two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment according to claim 1 or 2, characterized in that: The driving pressure of the nanofiltration membrane is between 0.2MPa-0.4MPa.

4. The two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment according to claim 1 or 2, characterized in that: A micro-nano bubble aerator is provided in the ceramic membrane assembly (9).

5. The two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment according to claim 1 or 2, characterized in that: A medium-pressure ultraviolet dechlorinator (26) is connected to the connecting pipeline between the anode chamber (8) of the ion exchange membrane electrolysis reactor and the acid liquid storage tank (11).

6. The two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment according to claim 1 or 2, characterized in that: The first stage nanofiltration membrane assembly (5) is a disc-tube nanofiltration membrane assembly.

7. The two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment according to claim 1 or 2, characterized in that: The two-stage nanofiltration membrane assembly (13) is a rolled nanofiltration membrane assembly.

8. A two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment according to claim 1 or 2, characterized in that: An aeration tower inlet pump (27) is provided on the connecting pipeline between the raw water inlet tank (1) and the waterfall aeration tower (2); a first-stage nanofiltration inlet pump (28) is provided on the connecting pipeline between the nanofiltration inlet tank (4) and the first-stage nanofiltration membrane group (5); a second-stage nanofiltration inlet pump (29) is provided on the connecting pipeline between the nanofiltration concentrated water regulating tank (12) and the second-stage nanofiltration membrane assembly (13); and an ion exchange membrane electrolysis inlet pump (30) is provided on the connecting pipeline between the salt water tank (14) and the ion exchange membrane electrolysis reactor.

9. A method for using the two-stage low-drug self-regulating nanofiltration coupling system for concentrated water treatment according to claim 1, characterized in that: The invention comprises a water production process, a concentrated water treatment process and a component cleaning process, wherein the water production process is as follows: raw water passes through a waterfall aeration tower (2), a self-driven ecological membrane ultrafiltration (3), a nanofiltration water inlet tank (4), and a nanofiltration membrane assembly (5) in sequence from a raw water inlet tank (1) to obtain nanofiltration produced water and nanofiltration concentrated water, wherein the nanofiltration produced water enters a nanofiltration produced water tank (6), and the nanofiltration concentrated water enters a concentrated water treatment process; the concentrated water treatment process is as follows: step 1, starting the ion exchange membrane electrolysis reactor: the nanofiltration concentrated water produced by the nanofiltration membrane assembly (5) is input into the cathode chamber (7) of the ion exchange membrane electrolysis reactor, and the anode chamber (8) of the ion exchange membrane electrolysis reactor is injected with salt starting liquid, and the reactor is powered on for operation; step 2, the cathode chamber (7) softens the concentrated water and removes organic matter: water electrolysis produces an alkaline environment, calcium and magnesium form particulate precipitation in the alkaline environment, and the formed particulate adsorbs organic matter to produce The generated alkaline mixture enters the ceramic membrane assembly (9); Step 3, the salt start-up liquid is discharged from the anode chamber (8): the salt start-up liquid in the anode chamber (8) of the ion exchange membrane electrolysis reactor is acidic after electrolysis and is discharged to the acid storage tank (11) for storage; Step 4, the ceramic membrane separates the alkaline mixture in the cathode chamber (7): the alkaline mixture in the cathode chamber (7) after electrolysis enters the ceramic membrane assembly (9), the ceramic membrane assembly (9) intercepts the particulate matter, and the clear alkaline solution flows into the anode chamber (8) of the ion exchange membrane electrolysis reactor; Step 5, the cathode chamber (7) is injected with new concentrated water: while the alkaline mixture in the cathode chamber (7) after electrolysis flows into the ceramic membrane assembly (9), the newly generated concentrated water is injected into the cathode chamber (7), and step 2 is repeated; Step 6, the anode chamber (8) is oxidized to adjust the pH of the concentrated water: after the clear alkaline solution is electrolyzed in the anode chamber (8), a portion of the organic matter is removed by oxidation, and the pH is adjusted After adjusting back to neutral, it is discharged into the nanofiltration concentrated water regulating box (12); step seven, the second-stage nanofiltration membrane component (13) produces water: the concentrated water pretreated in the nanofiltration concentrated water regulating box (12) enters the second-stage nanofiltration membrane component (13), and the produced water enters the nanofiltration produced water tank (6) to improve the system recovery rate; after startup, step two, step four to step seven are repeated; the component cleaning process includes nanofiltration membrane component cleaning and ceramic membrane component (9) cleaning: the nanofiltration membrane component cleaning includes the following steps: step one, cleaning liquid generation: the water in the salt water tank (14) flows into the cathode chamber (7) and the anode chamber (8) of the ion exchange membrane electrolysis reactor, after electrolysis The generated acid and alkali liquids are discharged into the acid liquid reserve tank (11) and the alkali liquid reserve tank (10) respectively; step 2, low flow cleaning: use the cleaning pressure pump (17) to replace the raw water with a low cleaning liquid pressure; step 3, circulation: the cleaning liquid enters the nanofiltration membrane assembly from the raw water inlet and discharges from the concentrated water interface. At this time, the valve on the connecting pipeline between the first stage nanofiltration membrane assembly (5) and the nanofiltration water inlet tank (4) and the valve on the connecting pipeline between the second stage nanofiltration membrane assembly (13) and the nanofiltration concentrated water regulating tank (12) are all in a closed state, and the cleaning liquid circulates back to the corresponding acid liquid reserve tank (11) and the alkali liquid reserve tank (10) to ensure that the cleaning liquid temperature is constant;Step 4, soaking: stop the cleaning pressure pump (17) and let the membrane element completely soak in the cleaning liquid; Step 5, high flow cleaning: use high flow circulating flushing liquid, and the pollutants are washed away by the cleaning liquid; Step 6, flushing: use pre-treated qualified produced water to flush the residual cleaning liquid in the nanofiltration system; Step 7, restart the system: restart the system after the cleaning is completed; The cleaning of the ceramic membrane assembly (9) includes the following steps: the acid liquid generated in the anode chamber (8) of the ion exchange membrane electrolysis reactor enters the water production end of the ceramic membrane assembly (9) after being pressurized by the backwash pump (20), and the backwash water of the ceramic membrane assembly (9) is discharged through the backwash water discharge pipe (21). ; 10. A method for using the two-stage low-drug self-regulated nanofiltration coupling system for concentrated water treatment according to claim 2, characterized in that: The invention comprises a water production process, a concentrated water treatment process and a component cleaning process, wherein the water production process is as follows: raw water passes through a waterfall aeration tower (2), a self-driven ecological membrane ultrafiltration (3), a nanofiltration water inlet tank (4), and a nanofiltration membrane assembly (5) in sequence from a raw water inlet tank (1) to obtain nanofiltration produced water and nanofiltration concentrated water, wherein the nanofiltration produced water enters a nanofiltration produced water tank (6), and the nanofiltration concentrated water enters a concentrated water treatment process; the concentrated water treatment process is as follows: step 1, starting the ion exchange membrane electrolysis reactor: the nanofiltration concentrated water produced by the nanofiltration membrane assembly (5) is input into the cathode chamber (7) of the ion exchange membrane electrolysis reactor, and the anode chamber (8) of the ion exchange membrane electrolysis reactor is injected with salt starting liquid, and the reactor is powered on for operation; step 2, the cathode chamber (7) softens the concentrated water and removes organic matter: water electrolysis produces an alkaline environment, calcium and magnesium form particulate precipitation in the alkaline environment, and the formed particulate adsorbs organic matter to produce The generated alkaline mixture enters the ceramic membrane assembly (9); Step 3, the salt start-up liquid is discharged from the anode chamber (8): the salt start-up liquid in the anode chamber (8) of the ion exchange membrane electrolysis reactor is acidic after electrolysis and is discharged to the acid storage tank (11) for storage; Step 4, the ceramic membrane separates the alkaline mixture in the cathode chamber (7): the alkaline mixture in the cathode chamber (7) after electrolysis enters the ceramic membrane assembly (9), the ceramic membrane assembly (9) intercepts the particulate matter, and the clear alkaline solution flows into the anode chamber (8) of the ion exchange membrane electrolysis reactor; Step 5, the cathode chamber (7) is injected with new concentrated water: while the alkaline mixture in the cathode chamber (7) after electrolysis flows into the ceramic membrane assembly (9), the newly generated concentrated water is injected into the cathode chamber (7), and step 2 is repeated; Step 6, the anode chamber (8) is oxidized to adjust the pH of the concentrated water: after the clear alkaline solution is electrolyzed in the anode chamber (8), a portion of the organic matter is removed by oxidation, and the pH is adjusted After being adjusted back to neutral, it is discharged into the nanofiltration concentrated water regulating tank (12); step seven, water production from the second-stage nanofiltration membrane assembly (13): the concentrated water pretreated in the nanofiltration concentrated water regulating tank (12) enters the second-stage nanofiltration membrane assembly (13), and the produced water enters the nanofiltration produced water tank (6) to improve the system recovery rate; after startup, step two, step four to step seven are repeated; the component cleaning process comprises the following steps: step one, cleaning liquid generation: the water in the salt water tank (14) flows into the cathode chamber (7) and the anode chamber (8) of the ion exchange membrane electrolysis reactor, and the acid and alkali liquids generated after electrolysis are respectively discharged into the acid liquid reserve tank (11) and the alkali liquid reserve tank (10); step two, low-flow cleaning: the cleaning booster pump (17) is used to replace the raw water with a low cleaning liquid pressure;Step 3, circulation: For the nanofiltration membrane assembly, the cleaning liquid enters from the raw water inlet and flows out from the concentrated water interface. For the ceramic membrane assembly (9), the cleaning liquid enters from the water production end and flows out from the water inlet end. At this time, the valve on the connecting pipeline between the first stage nanofiltration membrane assembly (5) and the nanofiltration water inlet tank (4), the valve on the connecting pipeline between the second stage nanofiltration membrane assembly (13) and the nanofiltration concentrated water regulating tank (12), the valve on the connecting pipeline between the ceramic membrane assembly (9) and the cathode chamber (7), and the valve on the connecting pipeline between the ceramic membrane assembly (9) and the anode chamber (8) are closed. The valves on the connecting pipelines are all in the closed state, and the cleaning liquid is circulated back to the corresponding acid storage tank (11) and the alkali storage tank (10) to ensure that the cleaning liquid temperature is constant; Step 4, soaking: stop the cleaning pressure pump (17) and let the membrane element completely soak in the cleaning liquid; Step 5, high-flow cleaning: use high-flow circulating flushing liquid, and the pollutants are washed away by the cleaning liquid; Step 6, flushing: use pre-treated qualified produced water to flush the residual cleaning liquid in the nanofiltration system; Step 7, restart the system: restart the system after the cleaning is completed. ;

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