Advanced purification treatment system for wastewater containing refractory organic matters

Abstract

The invention belongs to the technical field of industrial wastewater treatment, and particularly discloses a refractory organic matter-containing wastewater deep purification treatment system, which comprises a water inlet, a pretreatment unit, a persulfate advanced oxidation unit, a biological treatment unit, a membrane separation deep purification treatment unit, a disinfection tank, a water outlet, a sludge treatment unit and an evaporative crystallization unit. According to the invention, the synergistic effect of advanced oxidation-biological treatment-membrane separation deep purification treatment is utilized, firstly, the refractory organic matters are decomposed into the micromolecular organic matters through ultrasonic enhancement-catalytic oxidation, and then the efficient biodegradation of the micromolecular organic matters is realized by adopting a contact oxidation-moving bed bio-membrane reactor (A2 / O-MBBR) process. And finally, carrying out deep purification treatment on the wastewater through a graded membrane separation process (an ultrafiltration membrane and a reverse osmosis membrane), so that the effluent quality is improved, and the discharge and reuse requirements are met.

Description

Technical Field

[0001] The present invention relates to the field of water treatment technology, and in particular to a wastewater treatment system that integrates persulfate advanced oxidation, biodegradation and membrane separation technologies. The system is particularly suitable for treating and reusing industrial wastewater containing refractory organic matter such as antibiotics, heterocyclic compounds and halogenated hydrocarbons generated in the pharmaceutical, pesticide and dye industries. Background Art

[0002] With the rapid development of the pharmaceutical industry, persistent organic pollutants such as antibiotics, benzene rings, and polychlorinated biphenyls (PCBs) remain in large quantities in water bodies. Due to their persistence, biotoxicity, and the risk of transmitting drug-resistant genes, they pose a serious threat to the ecological environment and human health. Traditional wastewater treatment processes (such as activated sludge and coagulation sedimentation) are primarily designed for conventional pollutants and are difficult to achieve efficient degradation of these new pollutants.

[0003] Current treatment technologies for recalcitrant organic pollutants primarily include physical and chemical methods and biological treatment. Physical and chemical methods primarily include adsorption, coagulation, and chemical oxidation, but each of these technologies has varying degrees of limitations. While adsorption can rapidly concentrate pollutants, it involves only phase transfer, requiring subsequent treatment and resulting in high costs. Furthermore, adsorption performance is significantly affected by pollutant concentration and water quality conditions (such as pH and coexisting ions). Coagulation suffers from poor selectivity for organic pollutants, produces large amounts of sludge, and is prone to secondary pollution. Traditional chemical oxidation relies on hydroxyl radicals (•OH), which have a short half-life (<1 μs), a narrow pH range (requiring acidic conditions), and low oxidant utilization. Biological treatment, primarily the activated sludge process, can remove some organic matter, but microorganisms are susceptible to inhibition by organic matter, such as antibiotics, leading to fluctuations in treatment efficiency. Furthermore, antibiotics adsorbed by sludge may enter the environment through backflow, causing secondary pollution.

[0004] In recent years, advanced oxidation technology has attracted much attention due to its advantages of high efficiency, rapidity and thorough oxidation reaction. Among them, persulfate activation method has attracted much attention due to the sulfate radical (SO4 - •) has strong oxidation ability and long half-life (30-40 μs) and has broad application prospects, but the single oxidation process is easily affected by Cl in water. - , humic acid, and other pollutants, and may generate toxic intermediates. Although membrane separation technology can efficiently intercept small molecule pollutants and has a wide range of water quality applications, when applied to wastewater treatment processes, membrane fouling is a prominent problem and operating costs are high.

[0005] In summary, the current technical bottleneck lies in the independent operation of single physical, chemical and biological processes, which fail to achieve synergistic efficiency; the antibiotics enriched in the sludge by adsorption and biological methods are not completely degraded, posing a risk of secondary pollution; the adaptability to sewage water quality conditions is poor, and the treatment efficiency drops sharply when encountering complex water such as high salt and multiple coexisting ions. Summary of the Invention

[0006] In response to the problem that the composition of wastewater containing difficult-to-degrade organic matter such as antibiotics is becoming increasingly complex and it is difficult to treat it to meet emission standards using a single process, the present invention combines traditional biological treatment processes with physical and chemical treatment technologies such as persulfate advanced oxidation and membrane separation, and applies them to the treatment of difficult-to-degrade organic wastewater containing antibiotics, thereby improving the treatment efficiency of wastewater containing difficult-to-degrade organic matter and the water quality of the effluent to meet emission and reuse requirements.

[0007] The present invention provides a deep purification treatment system for wastewater containing refractory organic matter, comprising a water inlet, a pretreatment unit, a persulfate advanced oxidation unit, a biological treatment unit, a membrane separation deep purification treatment unit, a disinfection tank, a water outlet, a sludge treatment unit and an evaporation crystallization unit, characterized in that: the pretreatment unit comprises a grid decontamination machine, a cyclone grit chamber and a pH adjustment tank, wherein the pH adjustment adopts an intelligent control module, the pH of the effluent of the pH adjustment tank is 6.5-7.5, the persulfate advanced oxidation unit comprises a persulfate advanced oxidation reactor, a persulfate adding device and a catalyst adding device, and the biological treatment unit adopts a contact oxidation-moving bed biofilm reactor (A 2 / O-MBBR) process, including an anaerobic tank, an anoxic MBBR tank, an aerobic MBBR tank, and a secondary sedimentation tank. The membrane separation deep purification treatment unit includes a coagulation sedimentation tank, an intermediate water tank, an ultrafiltration module, and a reverse osmosis module. The pretreatment unit, persulfate advanced oxidation unit, biological treatment unit, membrane separation deep purification treatment unit, and disinfection tank are connected in sequence through corrosion-resistant pipes with flow control valves.

[0008] Furthermore, the persulfate advanced oxidation reactor has an upper cylindrical / lower conical structure with a height-to-diameter ratio of 3:1-5:1, and is equipped with a collaborative mixing system of an anchor-paddle composite flow propeller and an ultrasonic device. The anchor-paddle composite flow propeller adopts a double-layer 45° pitched-blade turbine with a rotation speed of 30-100 rp / min. There are 4-8 ultrasonic devices, which are arranged at equal intervals along the axis of the reactor, with an operating frequency of 20-100 kHz and a power density of 0.1-1.0 W / cm³. The upper part of the persulfate advanced oxidation reactor is filled with a packing layer, which is an activated alumina porous packing with a diameter of 5-10 mm and a filling height of 3-50 cm. A persulfate distributor and a catalyst distributor are provided below the packing layer, and the persulfate distributor and catalyst distributor adopt an annular porous water distribution pipe.

[0009] Furthermore, the persulfate in the persulfate addition device is a composite oxidant composed of sodium persulfate and ammonium persulfate in a mass ratio of 3:1-5:1, the persulfate dosage is 1.2-2.5 times the COD equivalent of the wastewater, and the reaction time is 30-90 minutes; the catalyst in the catalyst addition device uses Fe3O4, MnO2 and CuS nanoparticles in a mass ratio of 2:1:0.5, with a particle size distribution of 20-100 nm and a specific surface area of ​​≥150 cm 2 / g, and the catalyst dosage is 0.5-2.0 g / L.

[0010] Furthermore, the anoxic MBBR tank and the aerobic MBBR tank in the biological treatment unit are a combination of one or more sections, and both the anoxic MBBR tank and the aerobic MBBR tank are equipped with a submersible mixer and an aeration device. The dissolved oxygen in the anoxic MBBR tank is 0.2-0.5 mg / L, and the dissolved oxygen in the aerobic MBBR tank is 2.5-4.0 mg / L. Both the anoxic MBBR tank and the aerobic MBBR tank are filled with MBBR carriers with a filling rate of 30%-40%. The MBBR carrier is made of polyethylene with a density of 0.94-0.96 g / cm 3 The surface is modified by plasma grafting, with a specific surface area of ​​≥500 m 2 / m 3 .

[0011] Furthermore, an internal reflux pipe and an internal reflux pump are provided between the anoxic MBBR tank and the aerobic MBBR tank to return the sludge in the aerobic MBBR tank to the anoxic MBBR tank, with an internal reflux ratio of 150%-400%, a sludge concentration (MLSS) of 4-6 g / L, and a hydraulic retention time of 8-12 hours. An oxidation-reduction potential (ORP) monitor is provided at the outlet of the anoxic MBBR tank to control the carbon source addition system in linkage. An external reflux pipe and an external reflux pump are provided between the anaerobic tank and the secondary sedimentation tank to return the sludge in the secondary sedimentation tank to the anaerobic tank, with an external reflux ratio of 40%-150%.

[0012] Furthermore, the ultrafiltration module includes a booster pump, a precision filter and an ultrafiltration membrane assembly; the reverse osmosis module includes a booster pump, a low-pressure reverse osmosis membrane assembly, a high-pressure pump and a high-pressure reverse osmosis membrane assembly; the clean water produced by the low-pressure reverse osmosis membrane assembly and the high-pressure reverse osmosis membrane assembly enters the disinfection pool and, after disinfection, is transported to the reclaimed water users; the concentrated water produced by the low-pressure reverse osmosis membrane assembly enters the high-pressure reverse osmosis membrane assembly for further desalination and concentration, and the concentrated water discharged from the high-pressure reverse osmosis membrane assembly enters the evaporation and crystallization unit for evaporation and crystallization.

[0013] Furthermore, the ultrafiltration membrane assembly contains ultrafiltration membranes connected in series, and the ultrafiltration membranes are PVDF hollow fiber membranes with a molecular weight cutoff of 10-50 kDa, a pore size of 10-100 nm, and a membrane flux of 50-80 L / (m 2 ·h), operating pressure 0.15-0.25 MPa; the reverse osmosis membranes in the low-pressure reverse osmosis membrane assembly and the high-pressure reverse osmosis membrane assembly both adopt a spiral wound structure, the reverse osmosis membrane in the low-pressure reverse osmosis membrane assembly is an aromatic polyamide low-pressure reverse osmosis membrane, the operating pressure is 1.0-1.5 MPa, the desalination rate is ≥99%, and the water recovery rate is 50% to 90%, and the reverse osmosis membrane in the high-pressure reverse osmosis membrane assembly is an aromatic polyamide high-fouling resistance reverse osmosis membrane, the operating pressure is 4.0-5.0 MPa, the desalination rate is ≥99.5%, and the water recovery rate is 50% to 90%.

[0014] The present invention combines traditional biological treatment processes with physical and chemical treatment technologies such as persulfate advanced oxidation and membrane separation, fully utilizing the strong oxidizing ability of persulfate advanced oxidation technology, the low energy consumption of biological treatment technology, and the high purification degree of membrane separation technology. It can effectively improve the treatment efficiency of wastewater with refractory organic matter, enhance the effluent water quality, and meet the discharge and reuse requirements. The water quality of the present invention has a wide range of applicability, is less affected by upstream sewage discharge, has stable produced water quality, and can effectively degrade refractory organic matter such as antibiotics in sewage, thereby solving the secondary pollution problem caused by their enrichment in sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a process flow chart of the present invention.

[0016] Figure 2 Schematic diagram of the structure of the persulfate advanced oxidation reactor of the present invention.

[0017] Figure 3 It is a structural schematic diagram of the membrane separation deep purification treatment unit of the present invention. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below with reference to specific embodiments and accompanying drawings.

[0019] The process flow chart of the deep purification treatment system for wastewater containing refractory organic matter of the present invention is as follows: Figure 1As shown, it includes a water inlet 1, a pretreatment unit 2, a persulfate advanced oxidation unit 3, a biological treatment unit 4, a membrane separation deep purification treatment unit 5, a disinfection tank 6, a water outlet 7, a sludge treatment unit 8 and an evaporation crystallization unit 9, wherein the pretreatment unit 2 includes a screen decontamination machine 21, a cyclone sand settling tank 22 and a pH adjustment tank 23, the pH adjustment adopts an intelligent control module, the pH range of the effluent of the pH adjustment tank 23 is 6.5-7.5, and the solid suspended matter concentration (SS) of the wastewater after treatment by the pretreatment unit 2 is ≤100 mg / L, the persulfate advanced oxidation unit 3 includes a persulfate advanced oxidation reactor 31, a persulfate addition device 32, and a catalyst addition device 33, and the biological treatment unit 4 adopts a contact oxidation-moving bed biofilm reactor (A 2 / O-MBBR) process, including an anaerobic tank 41, an anoxic MBBR tank 42, an aerobic MBBR tank 43, and a secondary sedimentation tank 44. The membrane separation deep purification treatment unit 5 includes a coagulation sedimentation tank 51, an intermediate water tank 52, an ultrafiltration module 53, and a reverse osmosis module 54. The treatment units are connected in sequence through corrosion-resistant pipes with flow control valves, including a pretreatment unit 2, a persulfate advanced oxidation unit 3, a biological treatment unit 4, a membrane separation deep purification treatment unit 5, and a disinfection tank 6.

[0020] The structural diagram of the persulfate advanced oxidation reactor 31 is as follows: Figure 2 As shown, a water inlet 311 is provided at the top, the reactor is an upper cylindrical / lower conical structure, with a height-to-diameter ratio of 3:1-5:1, and is equipped with a coordinated mixing system of an anchor-paddle composite flow-maker 312 and an ultrasonic device 316, which can evenly mix the persulfate, catalyst and wastewater to be treated. The anchor-paddle composite flow-maker 312 adopts a double-layer 45° inclined-blade turbine with a rotation speed of 30-100 rp / min. There are 4-8 ultrasonic devices 316, which are arranged at equal intervals along the axis of the reactor, with an operating frequency of 20-100 kHz and a power density of 0.1-1.0 W / cm 3 The ultrasonic cavitation effect of the ultrasonic device can promote the generation of hydroxyl radicals on the catalyst surface, forming an oxidative synergistic effect with persulfate radicals. The upper portion of the persulfate advanced oxidation reactor 31 is filled with a packing layer 313. Packing layer 313 consists of porous activated alumina with a diameter of 5-10 mm and a filling height of 3-50 cm. Below packing layer 313 are a persulfate distributor 317 and a catalyst distributor 318. These two distributors utilize annular porous water distribution pipes.

[0021] The persulfate in the persulfate addition device 32 is a composite oxidant composed of sodium persulfate and ammonium persulfate in a mass ratio of 3:1-5:1. The oxidation efficiency is 50% higher than that of a single component. The persulfate dosage is 1.2-2.5 times the COD equivalent of the wastewater, and the reaction time is 30-90 minutes. The catalyst in the catalyst addition device 33 uses Fe3O4, MnO2 and CuS nanoparticles in a mass ratio of 2:1:0.5, with a particle size distribution of 20-100 nm and a specific surface area of ​​≥150 cm 2 / g, and the catalyst dosage is 0.5-2.0 g / L. After sufficient reaction, the wastewater supernatant flows into the biological treatment unit 4 through overflow weirs 314 and 315 by gravity, and the sludge is discharged from the sludge outlet 319 into the sludge treatment unit 8. After dehydration treatment in the dehydration device 82, it is transported for harmless disposal.

[0022] The anoxic MBBR tank 42 and the aerobic MBBR tank 43 in the biological treatment unit 4 are a combination of one or more sections. Both the anoxic MBBR tank 42 and the aerobic MBBR tank 43 are equipped with a submersible mixer and an aeration device. The dissolved oxygen in the anoxic MBBR tank 42 is 0.2-0.5 mg / L, and the dissolved oxygen in the aerobic MBBR tank 43 is 2.5-4.0 mg / L. Both the anoxic MBBR tank 42 and the aerobic MBBR tank 43 are filled with MBBR carriers with a filling rate of 30%-40%. The MBBR carrier is made of polyethylene with a density of 0.94-0.96 g / cm 3 The surface is modified by plasma grafting, with a specific surface area of ​​≥500 m 2 / m 3 An internal recirculation pipe and an internal recirculation pump are provided between the anoxic MBBR tank 42 and the aerobic MBBR tank 43 to return the sludge in the aerobic MBBR tank 43 to the anoxic MBBR tank 42. The internal recirculation ratio is 150%-400%, the sludge concentration (MLSS) is 4-6 g / L, the hydraulic retention time is 8-12 hours, and an oxidation-reduction potential (ORP) monitor is provided at the outlet of the anoxic MBBR tank 42 to control the carbon source addition system in a linkage manner. An external recirculation pipe and an external recirculation pump are provided between the anaerobic tank 41 and the secondary sedimentation tank 44 to return the sludge in the secondary sedimentation tank 44 to the anaerobic tank 41. The external recirculation ratio is 40%-150%.

[0023] Figure 3 The schematic diagram of the structure of the membrane separation deep purification treatment unit includes a coagulation sedimentation tank 51, an intermediate water tank 52, an ultrafiltration module 53, and a reverse osmosis module 54. The ultrafiltration module 53 includes a booster pump 531, a precision filter 532, and an ultrafiltration membrane assembly 533. The ultrafiltration membrane assembly 533 contains ultrafiltration membranes connected in series. The ultrafiltration membranes are PVDF hollow fiber membranes with a molecular weight cutoff of 10-50 kDa, a pore size of 10-100 nm, and a membrane flux of 50-80 L / (m2 h), operating pressure of 0.15-0.25 MPa; the reverse osmosis module 54 includes a booster pump 541 and a low-pressure reverse osmosis membrane assembly 542, a high-pressure pump 544 and a high-pressure reverse osmosis membrane assembly 545. The reverse osmosis membranes in the low-pressure reverse osmosis membrane assembly 542 and the high-pressure reverse osmosis membrane assembly 545 both adopt a spiral wound structure. The reverse osmosis membrane in the low-pressure reverse osmosis membrane assembly 542 is an aromatic polyamide low-pressure reverse osmosis membrane, with an operating pressure of 1.0-1.5 MPa, a desalination rate of ≥99%, and a water recovery rate of 50% to 90%. The reverse osmosis membrane in the high-pressure reverse osmosis membrane assembly 545 is an aromatic polyamide high-fouling resistance reverse osmosis membrane, with an operating pressure of 4.0-5.0 MPa, a desalination rate of ≥99.5%, and a water recovery rate of 50% to 90%. The clean water produced by the low-pressure reverse osmosis membrane assembly 542 and the high-pressure reverse osmosis membrane assembly 545 enters the disinfection pool 6, and after disinfection, is transported to the reclaimed water users; the concentrated water produced by the low-pressure reverse osmosis membrane assembly 542 enters the concentrated water pool 543, and is pumped to the high-pressure reverse osmosis membrane assembly 545 by the high-pressure pump 544 for further desalination and concentration. The concentrated water discharged from the high-pressure reverse osmosis membrane assembly 545 enters the evaporation crystallization unit 9 for evaporation and crystallization.

[0024] During operation, wastewater containing refractory organic matter enters pretreatment unit 2 from water inlet 1 for deslagging, degritting, pH adjustment, and sedimentation before entering persulfate advanced oxidation reactor 31. Under the action of persulfate and a catalyst, the refractory organic matter is broken down into small-molecule organic matter that is easily biochemically treated. The wastewater then enters biological treatment unit 4 for biochemical treatment to reduce COD, total nitrogen, ammonia nitrogen, and total phosphorus. After sedimentation in secondary sedimentation tank 44, the supernatant sequentially enters coagulation sedimentation tank 51, intermediate water tank 52, ultrafiltration module 53, and reverse osmosis module 54 to remove pollutants such as suspended matter, colloids, pigments, small-molecule organic matter, heavy metal ions, and soluble salts. The wastewater then enters disinfection tank 6 for sterilization and disinfection before being delivered to reclaimed water users through outlet 7. During the treatment process, sludge generated by persulfate advanced oxidation reactor 31, secondary sedimentation tank 44, and coagulation sedimentation tank 51 is pumped to sludge tank 81 via sludge pumps. After dehydration in dehydration device 82, the supernatant is transported for harmless disposal.

[0025] The above content describes the technical solution of the present invention in detail, but does not limit the scope of protection of the present invention. Ordinary technicians in this technical field can also make improvements and modifications on this basis, but these improvements and modifications are within the scope of protection of the claims of the present invention.

Claims

1. A deep purification treatment system for wastewater containing refractory organic matter, comprising a water inlet, a pretreatment unit, a persulfate advanced oxidation unit, a biological treatment unit, a membrane separation deep purification treatment unit, a disinfection tank, a water outlet, a sludge treatment unit, and an evaporation crystallization unit, characterized in that: The pretreatment unit includes a grid decontamination machine, a cyclone sand settling tank and a pH adjustment tank. The persulfate advanced oxidation unit includes a persulfate advanced oxidation reactor, a persulfate adding device and a catalyst adding device. The biological treatment unit adopts a contact oxidation-moving bed biofilm reactor (A 2 / O-MBBR) process, including an anaerobic tank, an anoxic MBBR tank, an aerobic MBBR tank, and a secondary sedimentation tank. The membrane separation deep purification treatment unit includes a coagulation sedimentation tank, an intermediate water tank, an ultrafiltration module, and a reverse osmosis module. The pretreatment unit, persulfate advanced oxidation unit, biological treatment unit, membrane separation deep purification treatment unit, and disinfection tank are connected in sequence through corrosion-resistant pipes with flow control valves.

2. The system for deep purification of wastewater containing refractory organic matter according to claim 1, characterized in that: The persulfate advanced oxidation reactor has an upper cylindrical / lower conical structure with a height-to-diameter ratio of 3:1-5:1 and is equipped with a coordinated mixing system of an anchor-paddle composite flowmaker and an ultrasonic device. The anchor-paddle composite flowmaker uses a double-layer 45° pitched-blade turbine with a rotation speed of 30-100 rp / min. The ultrasonic devices are 4-8 and are arranged at equal intervals along the reactor axis. The operating frequency is 20-100 kHz and the power density is 0.1-1.0 W / cm 3 The upper part of the persulfate advanced oxidation reactor is filled with a packing layer, which is a porous activated alumina packing with a diameter of 5-10 mm and a filling height of 3-50 cm. A persulfate distributor and a catalyst distributor are provided below the packing layer, and the persulfate distributor and the catalyst distributor adopt an annular porous water distribution pipe.

3. The system for deep purification of wastewater containing refractory organic matter according to claim 1, characterized in that: The persulfate in the persulfate addition device is a composite oxidant composed of sodium persulfate and ammonium persulfate in a mass ratio of 3:1-5:

1. The persulfate dosage is 1.2-2.5 times the COD equivalent of the wastewater, and the reaction time is 30-90 minutes. The catalyst in the catalyst addition device is Fe3O4, MnO2 and CuS nanoparticles in a mass ratio of 2:1:0.5, with a particle size distribution of 20-100 nm and a specific surface area of ​​≥150 cm 2 / g, and the catalyst dosage is 0.5-2.0 g / L.

4. The deep purification treatment system for wastewater containing refractory organic matter according to claim 1, characterized in that: The anoxic MBBR pool and the aerobic MBBR pool are a combination of one or more sections. Both the anoxic MBBR pool and the aerobic MBBR pool are equipped with a submersible mixer and an aeration device. The dissolved oxygen in the anoxic MBBR pool is 0.2-0.5 mg / L, and the dissolved oxygen in the aerobic MBBR pool is 2.5-4.0 mg / L. Both the anoxic MBBR pool and the aerobic MBBR pool are filled with MBBR carriers with a filling rate of 30%-40%. The MBBR carrier is made of polyethylene with a density of 0.94-0.96 g / cm 3 The surface is modified by plasma grafting, with a specific surface area of ​​≥500 m 2 / m 3 .

5. The deep purification treatment system for wastewater containing refractory organic matter according to claim 1, characterized in that: An internal reflux pipe and an internal reflux pump are provided between the anoxic MBBR tank and the aerobic MBBR tank to return the sludge in the aerobic MBBR tank to the anoxic MBBR tank. The internal reflux ratio is 150%-400%, the sludge concentration (MLSS) is 4-6 g / L, and the hydraulic retention time is 8-12 hours. An oxidation-reduction potential (ORP) monitor is provided at the outlet of the anoxic MBBR tank to control the carbon source addition system in a linkage manner. An external reflux pipe and an external reflux pump are provided between the anaerobic tank and the secondary sedimentation tank to return the sludge in the secondary sedimentation tank to the anaerobic tank. The external reflux ratio is 40%-150%.

6. The deep purification treatment system for wastewater containing refractory organic matter according to claim 1, characterized in that: The ultrafiltration membrane block contains ultrafiltration membranes connected in series, and the ultrafiltration membrane adopts polyvinylidene fluoride (PVDF) hollow fiber membrane with a molecular weight cutoff of 10-50 kDa, a pore size of 10-100 nm, and a membrane flux of 50-80 L / (m 2 ·h), operating pressure 0.15-0.25MPa; the reverse osmosis module contains a two-stage reverse osmosis of a low-pressure reverse osmosis membrane assembly and a high-pressure reverse osmosis membrane assembly, wherein the reverse osmosis membranes adopt a spiral wound structure, the operating pressure of the low-pressure reverse osmosis membrane assembly is 1.0-1.5 MPa, and the desalination rate is ≥99%, and the reverse osmosis membrane in the high-pressure reverse osmosis membrane assembly is a highly anti-fouling reverse osmosis membrane, the operating pressure is 4.0-5.0 MPa, and the desalination rate is ≥99.5%.

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