Desalted water preparation process flow and method

Abstract

The invention discloses a desalted water preparation technological process and method, and relates to the technical field of desalted water preparation.Compared with a traditional desalted water preparation method, the desalted water preparation technological process and method have the advantages that sterilization and algicide adding before ultrafiltration and before a reverse osmosis inlet is omitted; the high-density sedimentation tank is periodically cleaned by using a sterilization algicide, and microorganisms, organic matters and the like in source water are inhibited or eliminated in the high-density sedimentation tank in advance, so that the microorganisms, the organic matters and the like in the source water can be effectively prevented from entering a reverse osmosis device and a reverse osmosis membrane to cause biological pollution blockage on the reverse osmosis membrane; the stability and the reliability of preparation of the reverse osmosis membrane demineralized water are improved. The reverse osmosis membrane is effectively prevented from being damaged due to irreversible oxidation of the reverse osmosis membrane caused by sodium hypochlorite entering the reverse osmosis membrane, the service life of the reverse osmosis membrane is prolonged, the replacement and maintenance cost is reduced, the replacement and maintenance time of the reverse osmosis membrane is shortened, and the working continuity and the desalted water preparation efficiency are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of desalted water preparation, and specifically relates to a process flow and method for preparing desalted water. Background Art

[0002] Preparation of desalted water is a common process treatment method, usually using a full membrane water treatment process, namely ultrafiltration + reverse osmosis + EDI, which can effectively reduce the microorganisms, organic matter, etc. in the source water and ensure the effect of desalted water preparation.

[0003] In the related art, in the full-membrane water treatment process, different bactericides and algaecides are added before ultrafiltration and at the reverse osmosis inlet to eliminate organic macromolecules in the water production system, especially sodium hypochlorite is added as a bactericide and algaecide at the ultrafiltration inlet to ensure the reduction of microorganisms, organic matter, etc. in the source water; however, improper control of residual chlorine will cause irreversible oxidation of the reverse osmosis membrane, thereby causing damage to the reverse osmosis membrane, making it impossible to prepare demineralized water in a long-term and stable manner, greatly causing a waste of the reverse osmosis membrane, requiring frequent replacement of the reverse osmosis membrane, and increasing the preparation cost of demineralized water. Summary of the invention

[0004] The object of the present invention is to provide a process flow and method for preparing desalted water to solve at least one aspect of the problems and defects raised in the above-mentioned background technology.

[0005] Specifically, the present invention discloses a process and method for preparing desalted water, comprising the following steps:

[0006] S1. The source water is pumped into the integrated high-density sedimentation tank through the source water pump, and PAC and PAM are continuously added. After the source water is coagulated and precipitated, the water produced by the high-density sedimentation tank flows into the chemical water tank, and sodium hypochlorite is added to the high-density sedimentation tank for cleaning;

[0007] S2. The source water from the chemical water pool is pumped into the pre-filter through the chemical water pump, and the macromolecular substances and colloids in the source water are filtered before entering the ultrafiltration device. The ultrafiltration device further filters the molecular particles of the source water, and the produced water is collected in the ultrafiltration water tank, and the ultrafiltration device is cleaned at the same time;

[0008] S3. The purified water from the ultrafiltration water tank enters the primary security filter through the reverse osmosis water inlet booster pump, and the scale inhibitor and reducing agent are added at the same time. The purified water enters the primary reverse osmosis device through the primary high-pressure pump. After most of the ions are removed from the purified water, it is collected in the fresh water tank, and the secondary concentrated water is recovered to the ultrafiltration water tank;

[0009] S4. The fresh water in the fresh water tank enters the EDI security filter through the EDI water inlet booster pump. After filtering, the fresh water is collected in the EDI device. After the source water is further deionized by the EDI device, it flows into the demineralized water tank to complete the preparation of demineralized water for fresh water, and the concentrated water is recovered to the ultrafiltration water tank.

[0010] Compared with the traditional desalted water preparation method, the desalted water preparation process and method cancels the addition of bactericides and algaecides before ultrafiltration and before the reverse osmosis inlet, and instead uses bactericides and algaecides to periodically clean the high-density sedimentation tank, so as to suppress or eliminate microorganisms, organic matter, etc. in the source water in advance in the density sedimentation tank, which can effectively prevent microorganisms, organic matter, etc. in the source water from entering the reverse osmosis device and reverse osmosis membrane and causing biological fouling of the reverse osmosis membrane, thereby ensuring the stability of the desalted water quality and improving the stability and reliability of the reverse osmosis membrane desalted water preparation.

[0011] In addition, it can effectively prevent sodium hypochlorite from entering the reverse osmosis membrane, causing irreversible oxidation of the reverse osmosis membrane and damage to the reverse osmosis membrane, thereby reducing the replacement frequency of the reverse osmosis membrane and greatly improving the service life of the reverse osmosis membrane. It helps to reduce replacement and maintenance costs, and effectively reduces the replacement and maintenance time of the reverse osmosis membrane, improving work continuity and desalted water preparation efficiency.

[0012] As a further solution of the present invention: a secondary safety filter, a secondary high-pressure pump and a secondary reverse osmosis device are also arranged between the primary reverse osmosis device and the fresh water tank.

[0013] Since a secondary safety filter, a secondary high-pressure pump and a secondary reverse osmosis device are installed between the primary reverse osmosis device and the fresh water tank, trace pollutants and dissolved salts in the source water can be further removed, the water purity can be improved, the water treatment pressure of the primary reverse osmosis device can be improved, and the quality of the produced water and the desalination efficiency can be effectively improved.

[0014] As a further solution of the present invention: the primary security filter and the secondary security filter are both reverse osmosis security filters.

[0015] Since the primary security filter and the secondary security filter are both reverse osmosis security filters, they have very small pore sizes and can effectively remove tiny particles, sediments and suspended matter in the water. They can effectively prevent the reverse osmosis membrane from being blocked by microorganisms, organic matter and other pollutants in the source water, thereby ensuring the service life of the reverse osmosis membrane and reducing the replacement frequency of the reverse osmosis membrane, thereby reducing maintenance costs.

[0016] As a further solution of the present invention: an intermediate water tank and a booster pump are provided between the primary reverse osmosis device and the secondary safety filter.

[0017] By setting an intermediate water tank and a booster pump between the primary reverse osmosis device and the secondary safety filter, the stability, efficiency and reliability of water treatment can be effectively improved. The intermediate water tank can balance and store water, and the booster pump can ensure stable water pressure, thereby optimizing the working conditions of the secondary reverse osmosis and improving the overall water treatment effect. It can also reduce system failures and improve the stability and flexibility of desalted water preparation.

[0018] As a further solution of the present invention: the fresh water tank is provided with a reverse osmosis flushing pump, and the fresh water tank is connected to the primary reverse osmosis device and the secondary reverse osmosis device respectively through the reverse osmosis flushing pump.

[0019] Since the fresh water tank is provided with a reverse osmosis flushing pump, the fresh water tank is connected to the primary reverse osmosis device and the secondary reverse osmosis device respectively through the reverse osmosis flushing pump, so that the clean water in the fresh water tank can be effectively used to regularly flush the reverse osmosis membranes of the primary reverse osmosis device and the secondary reverse osmosis device, remove pollutants and sediments on the surface of the reverse osmosis membrane, reduce the contamination degree of the reverse osmosis membrane, ensure the permeability of the reverse osmosis membrane, and ensure its efficient desalted water preparation stability and efficiency.

[0020] As a further solution of the present invention: the high-density sedimentation tank is cleaned once every 7 to 15 days, and the agent used for each cleaning is sodium hypochlorite, and the amount of sodium hypochlorite used is 190 kg to 210 kg.

[0021] In summer, due to the rapid reproduction of algae, the high-density sedimentation tank is usually cleaned once every 7 days, and in winter, it is cleaned once every 15 days. 190kg-210kg of sodium hypochlorite is used as a bactericidal algaecide to inhibit or remove microorganisms, organic matter, etc. in the source water in advance. The dosage of sodium hypochlorite is preferably 200kg, which can effectively improve the erosion of the reverse osmosis membrane by residual chlorine, causing irreversible oxidation of the reverse osmosis membrane and causing its damage, so that it can not only inhibit or remove pollutants such as microorganisms and organic matter in the source water, but also ensure that the reverse osmosis membrane is free from residual chlorine erosion, ensuring the service life of the reverse osmosis membrane and the stability of the desalted water preparation function.

[0022] As a further solution of the present invention: the pre-filter is a laminated filter, and its filter pore size is 50 μm-200 μm.

[0023] Since the pre-filter is a laminated filter, its filtration pore size is 50μm-200μm, and the filtration pore size is preferably 100μm. The laminated filter has multiple superimposed filtration layers, which can effectively remove large particle impurities and suspended matter in the source water, reduce visible impurities in the water, prevent wear and blockage of subsequent water treatment equipment, improve the working efficiency of the entire water treatment system, and ensure that the subsequent water treatment equipment operates in the best state, thereby ensuring the reliability and efficiency of desalted water preparation.

[0024] As a further solution of the present invention: the pre-filter is a self-cleaning filter.

[0025] Since the pre-filter is the first filter in the water treatment system, the pre-filter has a very large filtering pressure. The self-cleaning function of the pre-filter can effectively improve the filtering pressure of the pre-filter, so that it can maintain a good filtering state and avoid the pre-filter being blocked by large particles and suspended matter in the source water. The pre-filter maintains a good filtering function and ensures the stability and effect of the source water pre-filtration.

[0026] As a further solution of the present invention: an ultrafiltration backwash water pump is arranged between the ultrafiltration device and the ultrafiltration water tank.

[0027] Since an ultrafiltration backwash water pump is arranged between the ultrafiltration device and the ultrafiltration water tank, the water in the ultrafiltration water tank passes through the backwash water pump to provide backwash water for the ultrafiltration device, and the water in the ultrafiltration water tank is filtered water with relatively pure water quality. The ultrafiltration device is backwashed with the filtered water to remove dirt and pollutants deposited on the surface of the ultrafiltration membrane, effectively reduce the degree of contamination of the ultrafiltration membrane, effectively maintain the permeability of the ultrafiltration membrane, ensure the processing efficiency and performance of the ultrafiltration device, and at the same time reduce the demand for additional water intake and save water resources.

[0028] As a further solution of the present invention: the ultrafiltration device is configured to be flushed once every 35 minutes to 45 minutes, and backwashed once every 24 hours with the addition of chemicals.

[0029] Since the ultrafiltration device is set to flush every 35 minutes to 45 minutes, it can effectively remove dirt and particulate matter on the surface of the ultrafiltration membrane, reduce the pollution of the ultrafiltration membrane, and effectively maintain the permeability of the ultrafiltration membrane, so that it maintains good filtration performance and state. At the same time, adding chemicals and backwashing every 24 hours can effectively remove microorganisms, organic matter, etc. in the source water, ensure the cleanliness of the water quality, reduce the filtration pressure for subsequent water treatment equipment, and ensure the stability and efficiency of desalted water preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0031] Figure 1 The present invention is a process flow chart for preparing desalted water. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the technical solution of the present invention is further specifically described below by way of examples and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation of the present invention.

[0033] In addition, in the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the disclosed embodiments. However, it is apparent that one or more embodiments may be implemented without these specific details. In other cases, known structures and devices are embodied in a schematic manner to simplify the accompanying drawings.

[0034] like Figure 1 The embodiment of the present invention is a process flow and method for preparing desalted water, comprising the following steps:

[0035] S1. The source water is pumped into the integrated high-density sedimentation tank through the source water pump, and PAC and PAM are continuously added. After the source water is coagulated and precipitated, the water produced by the high-density sedimentation tank flows into the chemical water tank, and sodium hypochlorite is added to the high-density sedimentation tank for cleaning;

[0036] S2. The source water from the chemical water pool is pumped into the pre-filter through the chemical water pump, and the macromolecular substances and colloids in the source water are filtered before entering the ultrafiltration device. The ultrafiltration device further filters the molecular particles of the source water, and the produced water is collected in the ultrafiltration water tank, and the ultrafiltration device is cleaned at the same time;

[0037] S3. The purified water from the ultrafiltration water tank enters the primary security filter through the reverse osmosis water inlet booster pump, and the scale inhibitor and reducing agent are added at the same time. The purified water enters the primary reverse osmosis device through the primary high-pressure pump. After most of the ions are removed from the purified water, it is collected in the fresh water tank, and the secondary concentrated water is recovered to the ultrafiltration water tank;

[0038] S4. The fresh water in the fresh water tank enters the EDI security filter through the EDI water inlet booster pump. After filtering, the fresh water is collected in the EDI device. After further deionization through the EDI device, the fresh water flows into the demineralized water tank, completing the preparation of demineralized water for the source water, and the concentrated water is recovered to the ultrafiltration water tank.

[0039] Specifically, compared with the traditional desalted water preparation method, the desalted water preparation process and method eliminates the addition of bactericides and algaecides before ultrafiltration and before the reverse osmosis inlet, and instead uses bactericides and algaecides to periodically clean the high-density sedimentation tank, so as to suppress or eliminate microorganisms, organic matter, etc. in the source water in the density sedimentation tank in advance, which can effectively prevent microorganisms, organic matter, etc. in the source water from entering the reverse osmosis device and reverse osmosis membrane and causing biological fouling of the reverse osmosis membrane, thereby ensuring the stability of the desalted water quality and improving the stability and reliability of the reverse osmosis membrane desalted water preparation.

[0040] In addition, it can effectively prevent sodium hypochlorite from entering the reverse osmosis membrane, causing irreversible oxidation of the reverse osmosis membrane and damage to the reverse osmosis membrane, thereby reducing the replacement frequency of the reverse osmosis membrane and greatly improving the service life of the reverse osmosis membrane. It helps to reduce replacement and maintenance costs, and effectively reduces the replacement and maintenance time of the reverse osmosis membrane, improving work continuity and desalted water preparation efficiency.

[0041] Furthermore, a secondary safety filter, a secondary high-pressure pump and a secondary reverse osmosis device are arranged between the primary reverse osmosis device and the fresh water tank.

[0042] Specifically, since a secondary safety filter, a secondary high-pressure pump and a secondary reverse osmosis device are also arranged between the primary reverse osmosis device and the fresh water tank, trace pollutants and dissolved salts in the source water can be further removed, the water purity can be improved, the water treatment pressure of the primary reverse osmosis device can be improved, and the quality of the produced water and the desalination efficiency can be effectively improved.

[0043] Furthermore, both the primary security filter and the secondary security filter are reverse osmosis security filters.

[0044] Specifically, since the first-level security filter and the second-level security filter are both reverse osmosis security filters, they have very small pore sizes and can effectively remove tiny particles, sediments and suspended matter in the water. They can effectively prevent the reverse osmosis membrane from being blocked by microorganisms, organic matter and other pollutants in the source water, thereby ensuring the service life of the reverse osmosis membrane, reducing the replacement frequency of the reverse osmosis membrane, and thus reducing maintenance costs.

[0045] Furthermore, an intermediate water tank and a booster pump are provided between the first-stage reverse osmosis device and the second-stage safety filter.

[0046] Specifically, by setting an intermediate water tank and a booster pump between the primary reverse osmosis device and the secondary safety filter, the stability, efficiency and reliability of water treatment can be effectively improved. The intermediate water tank can balance and store water, and the booster pump can ensure stable water pressure, thereby optimizing the working conditions of the secondary reverse osmosis, improving the overall water treatment effect, and reducing system failures, and improving the stability and flexibility of desalted water preparation.

[0047] Furthermore, if Figure 1 As shown, the fresh water tank is provided with a reverse osmosis flushing pump, and the fresh water tank is connected to the primary reverse osmosis device and the secondary reverse osmosis device respectively through the reverse osmosis flushing pump.

[0048] Specifically, since the fresh water tank is provided with a reverse osmosis flushing pump, the fresh water tank is connected to the primary reverse osmosis device and the secondary reverse osmosis device respectively through the reverse osmosis flushing pump, and the clean water in the fresh water tank can be effectively used to regularly flush the reverse osmosis membranes of the primary reverse osmosis device and the secondary reverse osmosis device, thereby removing pollutants and sediments on the surface of the reverse osmosis membrane, reducing the degree of contamination of the reverse osmosis membrane, ensuring the permeability of the reverse osmosis membrane, and ensuring its efficient desalted water preparation stability and efficiency.

[0049] According to an embodiment of the present invention, the high-density sedimentation tank is cleaned once every 7 to 15 days, and the agent used for each cleaning is sodium hypochlorite, and the amount of sodium hypochlorite used is 190 kg to 210 kg.

[0050] Specifically, in summer, due to the rapid reproduction of algae, the high-density sedimentation tank is usually cleaned once every 7 days, and in winter, it is cleaned once every 15 days. 190kg-210kg of sodium hypochlorite is used as a bactericidal algaecide to inhibit or remove microorganisms, organic matter, etc. in the source water in advance. The amount of sodium hypochlorite is preferably 200kg, which can effectively improve the erosion of the reverse osmosis membrane by residual chlorine, causing irreversible oxidation of the reverse osmosis membrane and causing its damage, so that it can not only inhibit or remove pollutants such as microorganisms and organic matter in the source water, but also ensure that the reverse osmosis membrane is free from residual chlorine erosion, thereby ensuring the service life of the reverse osmosis membrane and the stability of the desalted water preparation function.

[0051] According to an embodiment of the present invention, the pre-filter is a laminated filter, and the filter pore size thereof is 50 μm-200 μm.

[0052] Specifically, since the pre-filter is a laminated filter, its filtration pore size is 50μm-200μm, and the filtration pore size is preferably 100μm. The laminated filter has multiple superimposed filtration layers, which can effectively remove large particle impurities and suspended matter in the source water, reduce visible impurities in the water, prevent wear and blockage of subsequent water treatment equipment, improve the working efficiency of the entire water treatment system, ensure that the subsequent water treatment equipment operates in the best state, thereby ensuring the reliability and efficiency of desalted water preparation.

[0053] Furthermore, the pre-filter is a self-cleaning filter.

[0054] Specifically, since the pre-filter is the first filter in the water treatment system, the pre-filter has a very large filtering pressure. The self-cleaning function of the pre-filter can effectively improve the filtering pressure of the pre-filter, so that it can maintain a good filtering state and avoid the pre-filter being blocked by large particles and suspended matter in the source water. The pre-filter maintains a good filtering function and ensures the stability and effect of the source water pre-filtration.

[0055] like Figure 1 As shown, an ultrafiltration backwash water pump is arranged between the ultrafiltration device and the ultrafiltration water tank.

[0056] Specifically, since an ultrafiltration backwash water pump is arranged between the ultrafiltration device and the ultrafiltration water tank, the water in the ultrafiltration water tank is passed through the backwash water pump to provide backwash water for the ultrafiltration device, and the water in the ultrafiltration water tank is filtered water with relatively pure water quality. The ultrafiltration device is backwashed with the filtered water to remove dirt and pollutants deposited on the surface of the ultrafiltration membrane, effectively reduce the degree of contamination of the ultrafiltration membrane, effectively maintain the permeability of the ultrafiltration membrane, ensure the processing efficiency and performance of the ultrafiltration device, and at the same time reduce the demand for additional water intake, saving water resources.

[0057] Furthermore, the ultrafiltration device is set to be flushed once every 35 minutes to 45 minutes and backwashed once every 24 hours with the addition of chemicals.

[0058] Specifically, since the ultrafiltration device is set to flush every 35 minutes to 45 minutes, it can effectively remove dirt and particulate matter on the surface of the ultrafiltration membrane, reduce the pollution of the ultrafiltration membrane, and effectively maintain the permeability of the ultrafiltration membrane, so that it maintains good filtration performance and state. At the same time, adding chemicals and backwashing every 24 hours can effectively remove microorganisms, organic matter, etc. in the source water, ensure the cleanliness of the water quality, reduce the filtration pressure for subsequent water treatment equipment, and ensure the stability and efficiency of desalted water preparation.

[0059] The following are the number and rate of reverse osmosis membrane replacements from 2021 to 2023, as shown in Table 1:

[0060] Table 1

[0061] years 1# Water making equipment Replacement rate 2# Water making equipment Replacement rate 3# Water making equipment Replacement rate 2023 12 22％ 9 16.6％ 12 22％ 2022 6 11％ 12 22％ 3 5.5％ 2021 12 22％ 6 11％ 12 22％

[0062] It can be seen that through the desalted water preparation process and method, the front-end addition of sodium hypochlorite is eliminated, and the high-density sedimentation tank is cleaned regularly, the desalination rates of the three sets of water production equipment all meet the actual production requirements; during the process, the water quality did not exceed the standard, the reverse osmosis membrane did not oxidize and damage, and the conductivity of the produced water was able to remain stable; the frequency of reverse osmosis membrane maintenance was greatly reduced, and the replacement rate did not exceed 25%; the service life of the reverse osmosis membrane was greatly improved, ensuring the stability of the desalted water equipment operation.

[0063] The inlet flow, primary RO produced water conductivity and secondary RO produced water conductivity of the No. 1 water production equipment and the No. 2 water production equipment are tested as shown in Table 2:

[0064] Table 2

[0065]

[0066] It can be seen that through the desalted water preparation process and method, the front-end addition of sodium hypochlorite is eliminated, the high-density sedimentation tank is cleaned regularly, and the reverse osmosis inlet flow rate of the No. 1 water production equipment and the No. 2 water production equipment is greater than 30m 3 / h, the conductivity of the first-stage RO produced water is less than 10μS / cm, and the conductivity of the second-stage RO produced water is less than 2μS / cm. The water-making equipment can effectively filter out microorganisms, organic matter, etc. in the source water through the desalted water preparation process and method, greatly improving the water quality, and avoiding biological fouling of the reverse osmosis membrane, ensuring the stability of the desalted water quality, and at the same time avoiding sodium hypochlorite from entering the reverse osmosis membrane, causing irreversible oxidation of the reverse osmosis membrane, ensuring the performance and service life of the reverse osmosis membrane.

[0067] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process and method for preparing demineralized water, characterized in that: The steps include: S1. The source water is pumped into the integrated high-density sedimentation tank through the source water pump, and PAC and PAM are continuously added. After the source water is coagulated and precipitated, the water produced by the high-density sedimentation tank flows into the chemical water tank, and sodium hypochlorite is added to the high-density sedimentation tank for cleaning; S2. The source water from the chemical water pool is pumped into the pre-filter through the chemical water pump, and the macromolecular substances and colloids in the source water are filtered before entering the ultrafiltration device. The ultrafiltration device further filters the molecular particles of the source water, and the produced water is collected in the ultrafiltration water tank, and the ultrafiltration device is cleaned at the same time; S3. The purified water from the ultrafiltration water tank enters the primary security filter through the reverse osmosis water inlet booster pump, and the scale inhibitor and reducing agent are added at the same time. The purified water enters the primary reverse osmosis device through the primary high-pressure pump. After most of the ions are removed from the purified water, it is collected in the fresh water tank, and the secondary concentrated water is recovered to the ultrafiltration water tank; S4. The fresh water in the fresh water tank enters the EDI security filter through the EDI water inlet booster pump. After filtering, the fresh water is collected in the EDI device. After further deionization through the EDI device, the fresh water flows into the demineralized water tank to complete the preparation of demineralized water, and the concentrated water is recovered to the ultrafiltration water tank.

2. The process and method for preparing desalted water according to claim 1, characterized in that: A secondary safety filter, a secondary high-pressure pump and a secondary reverse osmosis device are also arranged between the primary reverse osmosis device and the fresh water tank.

3. The desalted water preparation process and method according to claim 2, characterized in that: The primary security filter and the secondary security filter are both reverse osmosis security filters.

4. The process and method for preparing desalted water according to claim 3, characterized in that: An intermediate water tank and a booster pump are arranged between the primary reverse osmosis device and the secondary safety filter.

5. The process and method for preparing desalted water according to claim 4, characterized in that: The fresh water tank is provided with a reverse osmosis flushing pump, and the fresh water tank is connected with the primary reverse osmosis device and the secondary reverse osmosis device respectively through the reverse osmosis flushing pump.

6. The process and method for preparing desalted water according to claim 1, characterized in that: The high-density sedimentation tank is cleaned once every 7 to 15 days. The agent used for each cleaning is sodium hypochlorite, and the amount of sodium hypochlorite used is 190 kg to 210 kg.

7. The process and method for preparing desalted water according to claim 1, characterized in that: The pre-filter is a laminated filter with a filter pore size of 50 μm-200 μm.

8. The process and method for preparing desalted water according to claim 7, characterized in that: The pre-filter is a self-cleaning filter.

9. The process and method for preparing desalted water according to claim 1, characterized in that: An ultrafiltration backwashing water pump is arranged between the ultrafiltration device and the ultrafiltration water tank.

10. The process and method for preparing desalted water according to claim 9, characterized in that: The ultrafiltration device is set to be flushed once every 35 minutes to 45 minutes and backwashed once every 24 hours by adding medicine.

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