Process for recovering copper sulfate and pure water in copper foil production wastewater

Abstract

The invention discloses a process for recovering copper sulfate and pure water in copper foil production wastewater, which comprises the following steps: introducing wastewater into an RO (Reverse Osmosis) membrane concentration and filtration module for concentration to obtain fresh water and concentrated water, recycling the obtained fresh water in a production line, and introducing the obtained concentrated water into a nanofiltration membrane filtration module; the nanofiltration membrane filtration module filters and concentrates the concentrated water to obtain concentrated water and fresh water, the fresh water obtained through nanofiltration flows back to the RO membrane concentration filtration module to be subjected to secondary concentration filtration, and the obtained concentrated water enters the sea fresh water membrane filtration module; the sea-fresh water membrane filtration module is used for filtering and concentrating the concentrated water for the third time to obtain a copper sulfate concentrated solution and fresh water, 2% of the copper sulfate concentrated solution is recycled, and 3% of the fresh water is centrally treated. Through the membrane filtration technology of two-stage RO membrane, nanofiltration membrane and high-pressure sea fresh membrane, copper sulfate in the wastewater is concentrated step by step, and finally the concentrated copper sulfate concentrated solution is reused in a production line copper dissolving tank; and double recovery of water resources and copper sulfate resources is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a process for recovering copper sulfate and pure water in copper foil production wastewater. Background Art

[0002] With the development of the new energy industry in recent years, especially for the core components of new energy, the demand for lithium batteries is also increasing. As a battery production process, it will be used in many industries, and lithium battery negative electrode material (copper foil) is one of the core components.

[0003] In the process of producing lithium battery negative electrode materials, each ton of copper foil product consumes about 15 tons of high-purity wastewater above 15M.Ω, and generates 15 tons of copper foil washing wastewater. The main pollutant in the copper foil washing wastewater is copper sulfate, and the copper ion concentration is about 300-350mg / L.

[0004] The conventional copper sulfate wastewater treatment process is to add sodium hydroxide (NaOH) chemical agent to convert the copper ions in the wastewater into copper hydroxide (Cu(OH)2) precipitate, and then add coagulants and flocculants for precipitation and separation, thereby achieving the treatment and purification effect.

[0005] However, the traditional process for treating lithium battery copper foil washing wastewater discharges a large amount of wastewater (15 tons / ton of product), generates a large amount of hazardous waste, and the main pollution source is Cu(OH)2. The copper ion concentration of copper foil washing wastewater is calculated at 0.33g / L, and the production of each ton of copper foil generates about 25Kg of Cu(OH)2 sludge (water content is 65%), which is a serious waste of resources.

[0006] In summary, a large amount of copper foil washing wastewater containing copper sulfate is generated during the production process of copper foil, the negative electrode material of lithium batteries. The raw water for washing water is high-purity water, and the components of the wastewater generated are relatively simple, mainly copper sulfate. If the wastewater is treated by traditional technology and meets the discharge standards, it will cause a large amount of water resources and copper sulfate resources to be wasted. Summary of the invention

[0007] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a water treatment field that solves the above-mentioned technical problems existing in the prior art.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A process for recovering copper sulfate and pure water from copper foil production wastewater, comprising an RO membrane concentration filtration module, a nanofiltration membrane filtration module, and a desalination membrane filtration module, and comprising the following steps:

[0010] S1. The wastewater is passed through the RO membrane concentration and filtration module for concentration to obtain 75% fresh water and 25% concentrated water. The 75% fresh water is further purified and reused in the production line. The 25% concentrated water is passed through the nanofiltration membrane filtration module. The copper ion content of the 25% concentrated water is ≥800 mg / L.

[0011] S2, the nanofiltration membrane filtration module further filters and concentrates the 25% concentrated water to obtain 5% concentrated water and 20% fresh water, and the 20% fresh water obtained by nanofiltration is returned to the RO membrane concentration filtration module for secondary concentration filtration, and the obtained 5% concentrated water enters the sea desalination membrane filtration module, and the copper ion content in the obtained 5% concentrated water is ≥3000mg / L;

[0012] S3, the desalinated membrane filtration module further filters and concentrates the 5% concentrated water to obtain a 2% copper sulfate concentrate and 3% fresh water, the 2% copper sulfate concentrate is reused, and the 3% fresh water is introduced into the wastewater treatment system for centralized treatment, and the copper ion content of the obtained 2% copper sulfate concentrate is ≥9000mg / L;

[0013] The filtrate temperature range is 10-30°C and the pH range is 2-9.

[0014] Further, the RO membrane concentration and filtration module includes a primary RO membrane concentration unit and a secondary RO membrane concentration unit;

[0015] The fresh water recovery rate of the primary RO membrane concentration unit is 75%, and the concentrated water recovery rate is 25%. The 75% fresh water obtained by the wastewater entering the primary RO membrane concentration unit enters the secondary RO membrane concentration unit, and the 25% concentrated water obtained enters the nanofiltration membrane filtration module;

[0016] The fresh water recovery rate of the secondary RO membrane concentration unit is 80%, and the concentrated water recovery rate is 20%. The fresh water filtered by the secondary RO membrane concentration unit is reused in the production line, and the concentrated water is returned to the primary RO membrane concentration unit for re-concentration and filtration.

[0017] Furthermore, in the RO membrane concentration and filtration module, the RO membrane used is a polyamide composite membrane with a filtration pore size of 0.08 to 0.1 nanometers; and the operating pressure is 35 to 41 bar.

[0018] Furthermore, the fresh water recovery rate of the nanofiltration membrane filtration module is 80%, a polyamide composite membrane is used, the filtration pore size is 1 to 2 nanometers, and the operating pressure is 35 to 41 bar.

[0019] Furthermore, the desalination membrane filtration module has a recovery rate of 60% of fresh water, uses a polyamide composite membrane, has a filtration pore size of less than 0.1 nanometers, and operates at a pressure of 65-70 bar.

[0020] Furthermore, the nanofiltration membrane filtration module includes a nanofiltration membrane pipeline, a fresh water return pipeline, and a concentrated water return discharge pipeline;

[0021] The nanofiltration membrane pipelines are arranged in multiple groups transversely, and the concentrated water produced by the RO membrane concentration and filtration module is introduced into the nanofiltration membrane pipeline through the first water inlet pipe arranged at the side, and then filtered through the nanofiltration membrane located in the nanofiltration membrane pipeline;

[0022] The generated fresh water flows back to the RO membrane concentration and filtration module through the fresh water return pipe;

[0023] The concentrated water generated flows into the desalination membrane filtration module through the concentrated water return discharge pipeline for further treatment.

[0024] Furthermore, the desalination membrane filtration module comprises a desalination membrane pipeline and a high-pressure pump;

[0025] The concentrated water treated by the nanofiltration membrane pipeline enters the desalination membrane pipeline for filtration through a second water inlet pipe arranged on the side, and the concentrated water is pressurized by a high-pressure pump. The desalination membrane pipeline is arranged horizontally, and multiple groups of desalination membrane pipelines are interconnected, so that the generated copper sulfate concentrate can be recycled.

[0026] Furthermore, the desalination membrane pipelines are arranged transversely, and a plurality of groups of desalination membrane pipelines are interconnected, and the concentrated water is pressurized and filtered in the desalination membrane pipelines through a circulation pump.

[0027] Furthermore, the desalinated water membrane filtration module also includes a storage tank, through which the fresh water generated by the RO membrane concentration filtration module is recovered.

[0028] Furthermore, a backwashing component is arranged on the desalinated membrane filtration module and the desalinated membrane filtration module.

[0029] Beneficial effects of the present invention:

[0030] 1. The "two-stage RO membrane + nanofiltration membrane + high-pressure desalination membrane" membrane filtration process adopted in this application concentrates the copper sulfate in the wastewater step by step, and the final concentrated copper sulfate concentrate is reused in the production line; the fresh water generated during the recovery process is further purified and reused in the pure water preparation system, realizing the dual recovery of water resources and copper sulfate resources.

[0031] 2. The process adopted in this application first uses RO to filter out fine particles that will damage the desalination membrane, and then separates water and copper sulfate through the desalination effect of the desalination membrane. The copper sulfate remains at the concentrated water end (the concentration becomes higher), and the water molecules pass through the desalination membrane into the fresh water end, thereby achieving the purpose of copper sulfate recovery.

[0032] 3. The design of the nanofiltration membrane filtration module and the desalination membrane filtration module used in this device takes into account efficiency, resource recycling, adaptability of operating conditions and system stability. Through reasonable module design and functional expansion, effective treatment and utilization of water resources are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0034] Figure 1 It is a schematic diagram of the overall process structure of an embodiment of the present invention;

[0035] Figure 2 Schematic diagram of the structure of the nanofiltration membrane filtration module according to an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the structural state of the desalination membrane filtration module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, an embodiment of the present invention provides a process for recovering copper sulfate and pure water in copper foil production wastewater, including an RO membrane concentration filtration module, a nanofiltration membrane filtration module, and a desalination membrane filtration module, and includes the following steps:

[0039] S1. The wastewater is passed into the RO membrane concentration and filtration module for concentration to obtain 75% fresh water and 25% concentrated water. The 75% fresh water obtained is further purified and reused in the production line, and the 25% concentrated water obtained enters the nanofiltration membrane filtration module. In order to ensure the efficiency of RO membrane filtration, the RO membrane concentration and filtration module includes a primary RO membrane concentration unit and a secondary RO membrane concentration unit; two filtrations are performed; wherein: the fresh water recovery rate of the primary RO membrane concentration unit is 75%, and the concentrated water recovery rate is 25%. The 75% fresh water obtained by the wastewater entering the primary RO membrane concentration unit continues to enter the secondary RO membrane concentration unit for filtration again, and the 25% concentrated water obtained enters the nanofiltration membrane filtration module.

[0040] The fresh water recovery rate of the secondary RO membrane concentration unit is 80%, and the concentrated water recovery rate is 20%. The fresh water filtered by the secondary RO membrane concentration unit is reused in the production line (i.e., it is made into primary pure water for the pure water station to make high-grade pure water. This refluxed fresh water can be directly used for the fresh water supply on the production line. Of course, it can also be further processed to form fresh water that can be directly discharged and meet the standards, or it can be stored for standby as needed). The concentrated water is returned to the primary RO membrane concentration unit for re-concentration and filtration.

[0041] At this time, the RO membrane used in the RO membrane concentration and filtration module is a polyamide composite membrane with a filtration pore size of 0.08 to 0.1 nanometers; the operating pressure is 35 to 41 bar. This RO membrane can effectively intercept all dissolved salts and organic matter with a molecular weight greater than 100, with a very high desalination rate, and the pH value range allowed for continuous operation is 2 to 11 (preferably 2 to 9), and the pH value range allowed for cleaning is 1 to 12. It has good chemical stability, is not easily invaded by microorganisms, and will not be compressed during operation, so the water output does not change with the use time. Some composite membranes have been used for 5 to 8 years, and their performance is still intact. The maximum operating temperature can reach 45°C, which can meet the direct treatment of high-temperature wastewater in industrial production.

[0042] The copper ion content in the obtained 25% concentrated water is ≥800 mg / L.

[0043] S2, the nanofiltration membrane filtration module further filters and concentrates the 25% concentrated water to obtain 5% concentrated water and 20% fresh water, and the 20% fresh water obtained by nanofiltration is returned to the RO membrane concentration filtration module for secondary concentration filtration, and the obtained 5% concentrated water enters the seawater desalination membrane filtration module,

[0044] At this time, the fresh water recovery rate of the nanofiltration membrane filtration module is 80%. It uses a polyamide composite membrane with a filtration pore size of 1 to 2 nanometers and an operating pressure of 35 to 41 bar. The nanofiltration membrane filtration module has good acid and alkali resistance, is suitable for processing various types of solutions, avoids blockage during dead-end filtration, improves filtration efficiency, has high processing output, low loss, compact structure, small footprint, and relatively low energy consumption. It can be used to collect active ingredients such as acid, alkali and alcohol in the solution to achieve resource recycling. It helps to maintain the balance of water quality, is not easy to block, and has strong resistance to pollutants. The filtration pore size is 1 to 2 nanometers and is evenly distributed, which makes the separation accuracy higher and the filtration process more stable.

[0045] It can be concentrated and purified at room temperature without changing the properties of the solution, and is particularly suitable for the treatment of heat-sensitive chemicals.

[0046] The copper ion content of the obtained 20% concentrated water is ≥3000 mg / L.

[0047] S3, the desalinated membrane filtration module further filters and concentrates the 5% concentrated water to obtain a 2% copper sulfate concentrate and 3% fresh water, the 2% copper sulfate concentrate is reused, and the 3% fresh water is introduced into the wastewater treatment system for centralized treatment, and the copper ion content of the obtained 2% copper sulfate concentrate is ≥9000mg / L;

[0048] At this time, the fresh water recovery rate of the desalination membrane filtration module is 60%. It adopts polyamide composite membrane with a filtration pore size less than 0.1 nanometers and an operating pressure of 65-70bar. It is suitable for high-pressure working environment. By improving the membrane element structure, the water output is increased, the number of membrane elements used is reduced, and the equipment investment is effectively reduced. It has superior performance in desalination rate, water flux, pressure resistance, anti-pollution performance and membrane performance stability.

[0049] Among them, the temperature range of the filtered filtrate is: 10-30°C; the pH range is: 2-9, which can achieve a better filtering effect.

[0050] The copper ion content of the raw water is 300mg / L. After passing through the two-stage RO membrane, the copper ion content of the concentrated water increases to 900mg / L (3 times), and then increases to 3000mg / L (10 times) through the nanofiltration membrane, and reaches 9000mg / L (50 times) after passing through the desalination membrane (the copper ion concentration is 12.6g / L); the temperature and pH change little. The copper dissolving tank reuse index is copper ion content ≥8000mg / L. A device for recovering copper sulfate and pure water from copper foil production wastewater.

[0051] like Figure 2 As shown, nanofiltration membrane filtration module

[0052] Nanofiltration membrane pipeline 1: It is the core part of the module. Multiple groups of nanofiltration membrane pipelines 1 are arranged horizontally to improve the filtration efficiency and processing capacity. Through the first water inlet pipe 101 arranged on the side, the nanofiltration membrane pipeline 1 receives the concentrated water produced by the RO membrane concentration filtration module.

[0053] Fresh water return pipe 11: The fresh water produced by filtration flows back to the RO membrane concentration filtration module through this pipe, realizing the recycling of fresh water and improving the utilization rate of water.

[0054] Concentrated water return discharge pipeline 12: The concentrated water produced by filtration flows into the desalination membrane filtration module through this pipeline for further treatment, thereby realizing the reuse and deep treatment of the concentrated water.

[0055] Backwash component: installed on the nanofiltration membrane filtration module, used to regularly clean the membrane surface, reduce pollution and extend the service life of the membrane.

[0056] Cross-flow filtration efficiency of nanofiltration membrane filtration module: The nanofiltration membrane filtration in the nanofiltration membrane pipeline 1 adopts a cross-flow filtration mode to maintain the shear force generated by a high flow rate on the membrane surface, effectively reduce membrane surface pollution, and improve filtration efficiency.

[0057] Resource recycling: The design of the fresh water return pipe 11 allows fresh water to be recycled, reducing the waste of water resources and lowering the processing cost.

[0058] Continuous operation pH range: The nanofiltration membrane can operate continuously in the pH range of 3-10, has strong adaptability, and can treat water with different pH values.

[0059] Maximum operating temperature and pressure: The maximum operating temperature of the nanofiltration membrane is 50°C, and the maximum operating pressure is 41 bar, which provides a wider operating window for the nanofiltration membrane to adapt to different operating conditions.

[0060] like Figure 3 As shown, desalination membrane filtration module

[0061] The desalination membrane pipeline 21 receives the concentrated water from the nanofiltration membrane pipeline 1 and performs further filtration treatment. The desalination membrane pipeline 21 is arranged horizontally, and multiple groups of pipelines are interconnected, which increases the processing capacity and efficiency.

[0062] High-pressure pump 22: pressurizes the concentrated water to improve the filtration efficiency and desalination rate. The use of the high-pressure pump allows the desalination membrane to operate at a higher pressure, thereby improving the desalination effect.

[0063] Circulation pump 23: pressurizes and filters the concentrated water in the desalination membrane pipeline 21, further improving the filtering efficiency and the stability of the system.

[0064] Storage tank: used to store the fresh water produced by the RO membrane concentration and filtration module, realizing the recovery and reuse of fresh water.

[0065] Desalination membrane filtration module has high desalination rate: Desalination membrane has high desalination rate, which can effectively remove salt from water and provide high-quality fresh water.

[0066] Pressure resistance: The maximum operating pressure of the desalination membrane is up to 69 bar, which is suitable for high-pressure working environment and improves the stability and reliability of the system.

[0067] Continuous operation pH range and temperature: The desalination membrane can operate continuously within the pH range of 2-11 and at a maximum temperature of 45°C. It has strong adaptability and is suitable for a variety of water quality conditions.

[0068] In this application, the design of the nanofiltration membrane filtration module and the desalination membrane filtration module takes into account efficiency, resource recycling, adaptability of operating conditions and system stability, and through reasonable module design and functional expansion, effective treatment and utilization of water resources are achieved.

[0069] In the embodiment of the present application, the second phase project of a copper foil production enterprise adopts the process of the present application and has been put into operation. The following table is the water quality monitoring record for one week at the end of September:

[0070] Water quality testing statistics

[0071]

[0072] As can be seen from the table above, the copper ion concentration of copper foil washing wastewater is about 0.33g / L. After step-by-step concentration and separation, the copper ion concentration of the desalinated membrane concentrated water finally reaches about 9g / L, and the concentration multiple reaches more than 27 times. The copper sulfate concentration in the concentrate meets the production requirements and is directly reused in the production line after further purification. It has been in operation for about 3 months and is in good condition.

[0073] The recovery rate of copper foil washing wastewater in the entire application reaches 95%, and the recovery rate of copper sulfate in copper foil washing wastewater reaches 95%. According to the current market price, for every ton of copper foil produced: about 5.25 kg of copper is recovered, saving about 410 yuan in resource costs; saving about 75 yuan in waste treatment costs, and 14 tons of primary pure water are recovered, saving about 49 yuan in water treatment costs; the total cost savings are about 534 yuan.

[0074] That is, the present application adopts a membrane filtration process of "two-stage RO membrane + nanofiltration membrane + high-pressure desalination membrane" to concentrate the copper sulfate in the wastewater step by step, and finally the concentrated copper sulfate concentrate is reused in the production line; the fresh water generated during the recovery process is further purified and reused in the pure water preparation system, realizing the dual recovery of water resources and copper sulfate resources.

[0075] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A process for recovering copper sulfate and pure water from copper foil production wastewater, comprising an RO membrane concentration filtration module, a nanofiltration membrane filtration module, and a desalination membrane filtration module, characterized in that: The following steps are involved: S1. The wastewater is passed through the RO membrane concentration and filtration module for concentration to obtain 75% fresh water and 25% concentrated water. The 75% fresh water is further purified and reused in the production line. The 25% concentrated water is passed through the nanofiltration membrane filtration module. The copper ion content of the 25% concentrated water is ≥800 mg / L. S2, the nanofiltration membrane filtration module further filters and concentrates the 25% concentrated water to obtain 5% concentrated water and 20% fresh water, and the 20% fresh water obtained by nanofiltration is returned to the RO membrane concentration filtration module for secondary concentration filtration, and the obtained 5% concentrated water enters the sea desalination membrane filtration module, and the copper ion content in the obtained 5% concentrated water is ≥3000mg / L; S3, the desalinated membrane filtration module further filters and concentrates the 5% concentrated water to obtain a 2% copper sulfate concentrate and 3% fresh water, the 2% copper sulfate concentrate is reused, and the 3% fresh water is introduced into the wastewater treatment system for centralized treatment, and the copper ion content of the obtained 2% copper sulfate concentrate is ≥9000mg / L; The filtrate temperature range is 10-30°C and the pH range is 2-9.

2. The process for recovering copper sulfate and pure water from copper foil production wastewater according to claim 1, characterized in that: The RO membrane concentration and filtration module includes a primary RO membrane concentration unit and a secondary RO membrane concentration unit; The fresh water recovery rate of the primary RO membrane concentration unit is 75%, and the concentrated water recovery rate is 25%. The 75% fresh water obtained by the wastewater entering the primary RO membrane concentration unit enters the secondary RO membrane concentration unit, and the 25% concentrated water obtained enters the nanofiltration membrane filtration module; The fresh water recovery rate of the secondary RO membrane concentration unit is 80%, and the concentrated water recovery rate is 20%. The fresh water filtered by the secondary RO membrane concentration unit is reused in the production line, and the concentrated water is returned to the primary RO membrane concentration unit for re-concentration and filtration.

3. The process for recovering copper sulfate and pure water from copper foil production wastewater according to claim 2, characterized in that: In the RO membrane concentration and filtration module, the RO membrane used is a polyamide composite membrane with a filtration pore size of 0.08 to 0.1 nanometers; the operating pressure is 35 to 41 bar.

4. The process for recovering copper sulfate and pure water from copper foil production wastewater according to claim 1, characterized in that: The nanofiltration membrane filtration module has a fresh water recovery rate of 80%, uses a polyamide composite membrane, has a filtration pore size of 1 to 2 nanometers, and operates at a pressure of 35 to 41 bar.

5. The process for recovering copper sulfate and pure water from copper foil production wastewater according to claim 1, characterized in that: The desalination membrane filtration module has a recovery rate of 60% of fresh water, adopts a polyamide composite membrane, has a filtration pore size of less than 0.1 nanometers, and operates at a pressure of 65-70 bar.

6. The process for recovering copper sulfate and pure water from copper foil production wastewater according to claim 1, characterized in that: The nanofiltration membrane filtration module comprises a nanofiltration membrane pipeline (1), a fresh water return pipeline (11), and a concentrated water return discharge pipeline (12); The nanofiltration membrane pipelines (1) are arranged in multiple groups transversely, and the nanofiltration membrane pipelines (1) are fed with concentrated water produced by the RO membrane concentration and filtration module through a first water inlet pipe (101) arranged at the side, and then filtered through the nanofiltration membrane located in the nanofiltration membrane pipeline (1); The generated fresh water flows back to the RO membrane concentration and filtration module through the fresh water return pipe (11); The generated concentrated water flows into the desalination membrane filtration module through the concentrated water return discharge pipeline (12) for further treatment.

7. The process for recovering copper sulfate and pure water from copper foil production wastewater according to claim 6, characterized in that: The desalinated water membrane filtration module comprises a desalinated water membrane pipeline (21) and a high-pressure pump (22); The concentrated water treated by the nanofiltration membrane pipeline (1) enters the desalination membrane pipeline (21) for filtration through a second water inlet pipe (201) arranged at the side, and the concentrated water is pressurized by a high-pressure pump (22). The desalination membrane pipeline (21) is arranged horizontally, and multiple groups of desalination membrane pipelines (21) are interconnected, so that the generated copper sulfate concentrate can be recycled.

8. The process for recovering copper sulfate and pure water from copper foil production wastewater according to claim 6, characterized in that: The desalination membrane pipelines (21) are arranged transversely, and a plurality of groups of desalination membrane pipelines (21) are interconnected. The concentrated water is pressurized and filtered in the desalination membrane pipelines (21) through a circulation pump (23).

9. The process for recovering copper sulfate and pure water from copper foil production wastewater according to claim 6, characterized in that: The desalinated water membrane filtration module also includes a storage tank, through which the fresh water generated by the RO membrane concentration filtration module is recovered.

10. The process for recovering copper sulfate and pure water from copper foil production wastewater according to claim 6, characterized in that: A backwashing component is arranged on the desalinated water membrane filtration module and the desalinated water membrane filtration module.

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