Water purification system, membrane module water purification process and membrane module cleaning process

Abstract

The invention relates to the technical field of membranes, in particular to a water purification system, a membrane assembly water purification process and a membrane assembly cleaning process. The water purification system comprises an ultrafiltration device, a reverse osmosis device, a cleaning water tank and a gas supply device, an ultrafiltration membrane and a bubble generator are arranged in a filtering water tank of the ultrafiltration device; a reverse osmosis membrane is arranged in the reverse osmosis device; the ultrafiltration device is communicated with the reverse osmosis device through a water purification pipeline; a first branch is led out of the clean water pipeline to be communicated with the cleaning water tank; the cleaning water tank is communicated with the reverse osmosis device through a flushing pipeline; a jet device is arranged on the flushing pipeline; the air supply device is communicated with the bubble generator through an air inlet pipeline, and a second branch is led out of the air inlet pipeline to be communicated with an inlet of the jet device. The ultrafiltration membrane and the reverse osmosis membrane are cleaned through bubble water, cleaning is more thorough, and water resources are saved; the small bubbles move and collide in water, so that impurities on the membrane and in membrane holes can be vibrated down; and small bubbles can also adsorb a part of pollutants on the membrane, so that a good cleaning effect is achieved, and meanwhile, membrane filaments are not damaged.

Description

Technical Field

[0001] The present invention relates to the field of membrane technology, and particularly to a water purification system, a water purification process for a membrane module, and a cleaning process. Background Art

[0002] Ultrafiltration membranes and reverse osmosis membranes are currently widely used water purification membrane modules. Ultrafiltration membranes mainly separate macromolecular colloids or suspended particles of a certain size from a solution through the sieving effect and electrostatic effect of the membrane; reverse osmosis generally uses the osmotic pressure difference as the driving force to intercept pollutants such as inorganic salts, heavy metal ions, organic matters, colloids, bacteria, and viruses through tiny pores. However, after long-term use, the problem of fouling of ultrafiltration membranes also arises. Impurities in the solution such as suspended solids, organic matters, microorganisms, and even a small amount of inorganic salts will deposit on the surfaces of ultrafiltration membranes and reverse osmosis membranes. Membrane fouling not only appears in the forms of adsorption, blockage, and interception, forming a gel and a filter layer on the surface of the membrane, but even leads to a large reproduction of microorganisms, resulting in a reduction in the filtration performance of the membrane module. Therefore, it is necessary to clean them regularly.

[0003] In the prior art, there are problems with the cleaning methods for flushing ultrafiltration membranes and reverse osmosis membranes. Either the ultrafiltration membranes and reverse osmosis membranes are hydraulically flushed, which requires a large amount of fresh water resources; or the ultrafiltration membranes and reverse osmosis membranes are manually cleaned, resulting in a large waste of manpower and easily tearing the membrane filaments. Summary of the Invention

[0004] In order to solve at least one of the above-mentioned disadvantages of the prior art, on the one hand, the present invention provides a water purification system, including: an ultrafiltration device, a reverse osmosis device, a cleaning water tank, and a gas supply device;

[0005] An ultrafiltration membrane is provided in the filtration water tank of the ultrafiltration device, and a bubble generator is provided below the ultrafiltration membrane; a reverse osmosis membrane is provided in the reverse osmosis device;

[0006] The water inlet of the ultrafiltration device is communicated with the raw water supply pipeline, and the water outlet of the ultrafiltration device is communicated with the water inlet of the reverse osmosis device through a purified water pipeline; a first branch is led out from the purified water pipeline and communicated with the water inlet of the cleaning water tank; the water outlet of the cleaning water tank is communicated with the water inlet of the reverse osmosis device through a flushing pipeline; a jet ejector is provided on the flushing pipeline;

[0007] The gas supply device is communicated with the bubble generator through an air inlet pipeline; a second branch is led out from the air inlet pipeline and connected to the inlet of the jet ejector.

[0008] Optionally, a booster pump is provided between the branch point of the ultrafiltration device and the first branch of the purified water pipeline. The first outlet of the booster pump is connected to the ultrafiltration device to generate a first working pressure on the ultrafiltration membrane; the second outlet of the booster pump is connected to the reverse osmosis device to generate a second working pressure on the reverse osmosis membrane;

[0009] A first control valve is provided on the purified water pipeline between the branch point of the first branch and the water inlet of the reverse osmosis device; a second control valve is provided on the first branch.

[0010] Optionally, the air supply device includes an air inlet, a gas compressor, and a third control valve, and the third control valve is provided between the air inlet and the gas compressor;

[0011] The gas compressor is communicated with the bubble generator through the air inlet pipeline; a fourth control valve is provided on the air inlet pipeline between the branch point of the second branch and the bubble generator;

[0012] The gas compressor is communicated with the inlet of the ejector through the second branch; a fifth control valve is provided on the second branch.

[0013] Optionally, a sixth control valve is provided on the flushing pipeline between the branch point of the second branch and the water outlet of the cleaning water tank.

[0014] Optionally, the purified water system further includes a first liquid level monitoring device, which is arranged in the filtration water tank. The first liquid level monitoring device is used to monitor the liquid level of the filtration water tank, and the liquid level of the filtration water tank is set with a first high liquid level, a first medium liquid level, and a first low liquid level.

[0015] Optionally, the purified water system further includes a second liquid level monitoring device, which is arranged in the cleaning water tank. The second liquid level monitoring device is used to monitor the liquid level of the cleaning water tank, and the liquid level of the cleaning water tank is set with a second high liquid level and a second low liquid level.

[0016] Optionally, the first liquid level monitoring device is electrically connected to the system control unit, and both the second control valve and the fourth control valve are electrically connected to the system control unit;

[0017] When the liquid level in the filtration water tank monitored by the first liquid level monitoring device is higher than the first medium liquid level under the condition that the preset cleaning condition is not met, the system control unit controls the second control valve and the fourth control valve to close, so that the ultrafiltration membrane purifies the liquid in the filtration water tank;

[0018] When the first liquid level monitoring device monitors that the liquid level in the filtration water tank is not lower than the first medium liquid level under the condition of meeting the preset cleaning conditions, the system control unit controls the fourth control valve to open, so that the gas supply device provides the gas medium to the bubble generator to clean the ultrafiltration membrane;

[0019] When the ultrafiltration membrane is cleaned until the preset cleaning time is met and the first liquid level monitoring device monitors that the liquid level in the filtration water tank is not lower than the first medium liquid level, the system control unit controls the second control valve to open, so that the liquid in the filtration water tank flows through the booster pump to the cleaning water tank.

[0020] Optionally, the second liquid level monitoring device is electrically connected to the system control unit, and the fifth control valve is electrically connected to the system control unit;

[0021] When the second liquid level monitoring device monitors that the liquid level in the cleaning water tank is higher than the second low liquid level and lower than the second high liquid level under the condition of meeting the preset cleaning conditions, the system control unit controls the fifth control valve to open, so that the gas supply device provides the gas medium to the ejector to generate bubble water to clean the reverse osmosis membrane.

[0022] Optionally, the water purification system further includes:

[0023] A first sewage discharge device, which is connected to the waste liquid outlet of the ultrafiltration device through a first sewage discharge pipeline; a seventh control valve is arranged between the first sewage discharge device and the ultrafiltration device;

[0024] A second sewage discharge device, which is connected to the waste liquid outlet of the reverse osmosis device through a second sewage discharge pipeline; an eighth control valve is arranged between the second sewage discharge device and the reverse osmosis device.

[0025] On the other hand, the present invention provides a membrane module cleaning process based on the water purification system as described above. Under the condition of meeting the preset cleaning conditions, the cleaning process includes the following steps:

[0026] When water is supplied to the filtration water tank through the raw water supply pipeline to the water inlet of the ultrafiltration device until the liquid level in the filtration water tank meets the first preset condition, the gas supply device provides the gas medium to the bubble generator in the ultrafiltration device through the air inlet pipeline, and the bubble generator generates bubbles in the liquid in the filtration water tank to clean the ultrafiltration membrane;

[0027] After the ultrafiltration membrane is cleaned until the first preset cleaning time is reached, the waste liquid after cleaning the ultrafiltration membrane in the ultrafiltration device is discharged until the liquid level in the filtration water tank meets the second preset condition;

[0028] Continue to replenish water into the filtration water tank through the raw water supply pipeline. When the liquid level in the filtration water tank meets the third preset condition, supplement the liquid purified by the ultrafiltration membrane in the filtration water tank into the cleaning water tank;

[0029] The gas supply device supplies the gas medium to the ejector through the second branch, and the ejector mixes the gas medium with the liquid flowing from the cleaning water tank to the ejector to form bubble water;

[0030] Discharge the bubble water into the reverse osmosis device through the flushing pipeline to clean the reverse osmosis membrane. After cleaning the reverse osmosis membrane until the second preset cleaning time is reached, discharge the waste liquid after cleaning the reverse osmosis membrane.

[0031] On the other hand, the present invention also provides a membrane module water purification process based on the water purification system as described above. In the case where the preset cleaning conditions are not met, the water purification process includes the following steps:

[0032] Supply water to the filtration water tank through the inlet of the ultrafiltration device via the raw water supply pipeline. When the liquid level in the filtration water tank meets the fourth preset condition, the ultrafiltration membrane purifies the liquid in the filtration water tank;

[0033] The liquid purified by the ultrafiltration membrane flows through the outlet of the ultrafiltration device and the inlet of the reverse osmosis device through the purified water pipeline, reaches the reverse osmosis device, and the reverse osmosis membrane purifies the liquid;

[0034] The liquid purified by the reverse osmosis membrane flows out through the outlet of the reverse osmosis device to obtain purified water.

[0035] Adopting the above technical solutions, the present invention has the following beneficial effects:

[0036] For the cleaning of the ultrafiltration membrane, the gas medium provided by the gas supply device enters the bubble generator and generates a large number of bubbles in water, and then the ultrafiltration membrane is cleaned through the bubbles and water. Compared with the commonly used hydraulic flushing, it can clean more deeply and thoroughly, and save water resources within the same cleaning time. For the cleaning of the reverse osmosis membrane, the purified water in the ultrafiltration device is used. A jet injector is set to mix the water in the cleaning water tank and the gas medium provided by the gas supply device to obtain bubble water. The flushing pipeline transports the bubble water to the reverse osmosis device to flush the reverse osmosis membrane. By cleaning the reverse osmosis membrane with bubble water, the small bubbles move and collide in water to generate a small-range oscillation on the reverse osmosis membrane, so as to shake off the contaminants with strong adhesion on the membrane and in the membrane pores, and at the same time, the membrane structure will not be damaged. And by using the adsorption effect of small bubbles, part of the contaminants on the membrane can be adsorbed into the liquid, achieving a good cleaning effect without damaging the membrane filaments. Moreover, the water filtered by the ultrafiltration device is used to clean the ultrafiltration membrane and the reverse osmosis membrane, ensuring that there are no suspended particles in the flushing water, and at the same time removing residual trace colloids, microorganisms, etc., to avoid contaminating or damaging the membrane during the cleaning process, thereby playing a protective role for the ultrafiltration membrane and the reverse osmosis membrane.

[0037] Other features and advantages of the present invention will be described in detail in the following specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and the same reference numerals generally represent the same components. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a schematic diagram of the overall structure of a water purification system according to an embodiment of the present invention.

[0040] The following is a supplementary description of the drawings:

[0041] 1 - Ultrafiltration device; 11 - Ultrafiltration membrane; 12 - Bubble generator; 13 - First liquid level monitoring device; 14 - First sewage discharge device; 2 - Reverse osmosis device; 21 - Reverse osmosis membrane; 22 - Second sewage discharge device; 3 - Cleaning water tank; 31 - Second liquid level monitoring device; 4 - Gas supply device; 41 - Air inlet; 42 - Compressor pump; 5 - Booster pump; 6 - Jet injector; L1 - Raw water supply pipeline; L2 - Purified water pipeline; L3 - First branch; L4 - Flushing pipeline; L5 - Air inlet pipeline; L6 - Second branch; K1 - First control valve; K2 - Second control valve; K3 - Third control valve; K4 - Fourth control valve; K5 - Fifth control valve; K6 - Sixth control valve; K7 - Seventh control valve; K8 - Eighth control valve. Detailed implementation manners

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0043] As used herein, the term "one embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0044] Reference Figure 1 , the embodiments of the present invention first provide a water purification system, including an ultrafiltration device 1, a reverse osmosis device 2, a cleaning water tank 3, and a gas supply device 4.

[0045] Specifically, the water purification system is composed of two parts of water purification devices, namely an ultrafiltration device 1 and a reverse osmosis device 2. The water purification system in the embodiments of the present invention has the functions of purifying water and cleaning the membrane components in the ultrafiltration device 1 and the reverse osmosis device 2.

[0046] The water inlet of the ultrafiltration device 1 is connected to the raw water supply pipeline L1, and the water outlet of the ultrafiltration device 1 is connected to the water inlet of the reverse osmosis device 2 through a purified water pipeline L2; the ultrafiltration device 1 is used to filter the raw water conveyed by the raw water supply pipeline L1, and the purified water pipeline L2 conveys the water filtered by the ultrafiltration device 1 to the reverse osmosis device 2 for further filtration by the reverse osmosis device 2.

[0047] The ultrafiltration device 1 includes a filtration water tank, an ultrafiltration membrane 11, and a bubble generator 12. The ultrafiltration membrane 11 plays a role in purifying water filtration. The ultrafiltration membrane 11 is generally made of polymer materials such as cellulose acetate, cellulose acetate esters, polyethylene, polysulfone, and polyamide. The ultrafiltration membrane 11 is disposed in the filtration water tank and can separate macromolecular colloids or suspended particles of a certain size from the raw water. The bubble generator 12 is disposed below the ultrafiltration membrane 11 and is used to introduce a gas medium to generate bubbles in the water to clean the ultrafiltration membrane 11. The subsequent cleaning process will be introduced in detail.

[0048] In some embodiments, the filtration water tank is provided with a water inlet, a water outlet, a sewage outlet, and an exhaust port. The water inlet of the filtration water tank is connected to the raw water supply pipeline L1. The water outlet of the filtration water tank is connected to the water inlet of the reverse osmosis device 2 through a purified water pipeline L2. The sewage outlet is disposed below the filtration water tank and is used to discharge the sewage for cleaning the ultrafiltration membrane 11. The exhaust port is disposed above the filtration water tank and is used to discharge the excess gas generated by the bubble generator 12.

[0049] The reverse osmosis device 2 is provided with a reverse osmosis membrane 21. The reverse osmosis membrane 21 is an artificial semi-permeable membrane with certain characteristics made by simulating biological semi-permeable membranes and is the core component of the reverse osmosis technology. Its working principle is that under the action of a pressure higher than the osmotic pressure of the solution, impurities and water are separated based on the fact that other substances cannot pass through the semi-permeable membrane. The membrane pore diameter of the reverse osmosis membrane 21 is very small, so it can effectively remove dissolved salts, colloids, microorganisms, organic matter, etc. in the water.

[0050] In a possible implementation manner, a booster pump 5 is disposed on the purified water pipeline L2. The first outlet of the booster pump 5 is connected to the ultrafiltration device 1 and is used to generate a first working pressure on the ultrafiltration membrane 11. The second outlet of the booster pump 5 is connected to the reverse osmosis device 2 and is used to generate a second working pressure on the reverse osmosis membrane 21. A first control valve K1 is provided on the purified water pipeline L2 between the booster pump 5 and the water inlet of the reverse osmosis device 2.

[0051] The booster pump 5 in the embodiment of the present invention can be a self-priming booster pump 5 with two-way cut-off, which can generate a gas pressure lower than atmospheric pressure, that is, negative pressure, at the first outlet and the second outlet, and respectively provide a first working pressure for the ultrafiltration membrane 11 and a second working pressure for the reverse osmosis membrane 21. The first control valve K1 is used to control the purified water pipeline L2 to transport the water in the ultrafiltration device 1 to the reverse osmosis device 2.

[0052] In a possible implementation, the ultrafiltration device 1 further includes a first liquid level monitoring device 13. The first liquid level monitoring device 13 is disposed in the filtration water tank. The first liquid level monitoring device 13 is used to monitor the liquid level of the filtration water tank. The liquid level of the filtration water tank is set with a first high liquid level, a first medium liquid level, and a first low liquid level. Further, the first liquid level monitoring device 13 is electrically connected to the system control unit. The system control unit determines how to control other components based on the electrical signal of the first liquid level monitoring device 13.

[0053] Specifically, the first liquid level monitoring device 13 in the embodiment of the present invention may be a liquid level float gauge, which is composed of components such as a float and a plug rod. The first liquid level monitoring device 13 can be installed on the top of the filtration water tank through a connecting flange. The float floats on the liquid surface according to the principle of equal displaced liquid volume. When the liquid level of the filtration water tank changes, the float also moves up and down. Due to the magnetic effect, the dry reed of the float level gauge is magnetically attracted, converting the liquid level position into an electrical signal, which is sent to the display instrument and the system control unit. The actual position of the liquid is digitally displayed by the display instrument, and the first liquid level monitoring device 13 thus achieves remote detection and control of the liquid level. In the embodiment of the present invention, the ultrafiltration membrane 11 is placed between the first medium liquid level and the first low liquid level. Raw water is transported to the filtration water tank. When the first liquid level monitoring device 13 detects that the water level in the filtration water tank is greater than the first medium liquid level, the system control unit controls the first control valve K1 to open and the booster pump 5 to start. The negative pressure generated by the booster pump 5 provides a first working pressure for the ultrafiltration membrane 11 and a second working pressure for the reverse osmosis membrane 21, so that the reverse osmosis membrane 21 can provide sufficient osmotic pressure.

[0054] The above is the water purification principle and process of the water purification system in the embodiment of the present invention. Next, it will be introduced how to clean the ultrafiltration membrane 11 and the reverse osmosis membrane 21 using the water purification system. Continuing to refer to Figure 1 , the air supply device 4 is connected to the bubble generator 12 through the air inlet pipeline L5. A first branch L3 is led out from the water purification pipeline L2 and connected to the water inlet of the cleaning water tank 3; the water outlet of the cleaning water tank 3 is connected to the water inlet of the reverse osmosis device 2 through the flushing pipeline L4; a jet pump 6 is provided on the flushing pipeline L4; a second branch L6 is led out from the air inlet pipeline L5 and connected to the inlet of the jet pump 6.

[0055] Specifically, the water in the filtration water tank is the water purified by the ultrafiltration membrane 11, which is used to clean the ultrafiltration membrane 11 placed in the cleaning water tank 3, and enters the cleaning water tank 3 through the water purification pipeline L2 and the first branch L3. The water in the cleaning water tank 3 enters the reverse osmosis device 2 through the flushing pipeline L4 and the jet pump 6, and is used to clean the reverse osmosis membrane 21.

[0056] The gas supply device 4 is used to provide a gas medium, which is first connected to the bubble generator 12 through the intake pipeline L5. In the embodiment of the present application, the bubble generator 12 can be an aeration head, which can realize strong contact between gas and water to generate bubbles. The bubble generator 12 is placed below the ultrafiltration membrane 11. The gas medium provided by the gas supply device 4 enters the bubble generator 12 and generates a large number of bubbles in the water, and then the ultrafiltration membrane 11 is cleaned through the bubbles and water. Compared with the commonly used hydraulic flushing, it can clean more deeply and thoroughly, and save water resources within the same cleaning time.

[0057] In the embodiment of the present invention, the ejector 6 can adopt a Venturi device. According to the Venturi tube principle and fluid mechanics knowledge, by using the change of the structural slope, the water flow velocity is changed to drive the addition of gas, and the water and gas are mixed and dissolved by using the pressure difference to obtain bubble water for flushing the reverse osmosis membrane 21. The ejector 6 is arranged between the cleaning water tank 3 and the reverse osmosis device 2 through the flushing pipeline L4. The inlet of the ejector 6 includes a water inlet and a gas inlet. The water in the cleaning water tank 3 is connected to the water inlet of the ejector 6 through the flushing pipeline L4, that is, the cleaning water tank 3 provides a water source for the ejector 6; the gas supply device 4 is connected to the gas inlet of the ejector 6 through the second branch L6, that is, the gas supply device 4 provides a gas source for the ejector 6; the outlet of the ejector 6 is connected to the water inlet of the reverse osmosis device through the flushing pipeline L4. When the ejector 6 mixes water and gas medium inside its structure to obtain bubble water, the flushing pipeline L4 transports the bubble water to the reverse osmosis device 2 to flush the reverse osmosis membrane 21. The cleaning water tank 3 can also be provided with an exhaust hole for discharging the excess gas in the cleaning water tank 3.

[0058] By flushing the reverse osmosis membrane 21 with bubble water, the small bubbles move and collide in the water to generate a small range of oscillations on the reverse osmosis membrane 21, so as to shake off the contaminants with strong adhesion on the membrane and inside the membrane pores, and at the same time will not damage the membrane structure; and by using the adsorption effect of small bubbles, part of the contaminants on the membrane can be adsorbed into the liquid, achieving a good cleaning effect and at the same time will not damage the membrane filaments.

[0059] Through the above implementation manner of the present invention, the water filtered by the ultrafiltration device 1 is used to clean the ultrafiltration membrane 11 and the reverse osmosis membrane 21, ensuring that the flushing water does not contain suspended particles, and at the same time removing residual trace colloids, microorganisms, etc., to avoid contaminating or damaging the membrane during the cleaning process, thereby playing a protective role for the ultrafiltration membrane 11 and the reverse osmosis membrane 21.

[0060] In a possible implementation, the booster pump 5 is arranged between the branch point of the ultrafiltration device 1 and the first branch L3, and the first control valve K1 is arranged between the branch point of the first branch L3 and the water inlet of the reverse osmosis device 2; and a second control valve K2 is provided on the first branch L3. In the embodiment of the present invention, the first control valve K1 and the second control valve K2 can be solenoid valves, which can be electrically connected to the system control unit, and the system control unit can control the opening and closing of the first control valve K1 and the second control valve K2. The second control valve K2 is used to control the water in the filtration water tank to flow to the cleaning water tank 3 through the purified water pipeline L2, the booster pump 5 and the first branch L3. During the water purification process, the first control valve K1 is open and the second control valve K2 is closed; during the cleaning process, the first control valve K1 is closed and the second control valve K2 is open.

[0061] In a possible implementation, the air supply device 4 includes an air inlet 41, a compressor pump 42 and a third control valve K3, and the third control valve K3 is arranged between the air inlet 41 and the compressor pump 42; the compressor pump 42 is communicated with the bubble generator 12 through an air supply pipeline L5; a fourth control valve K4 is provided between the branch point of the second branch L6 and the bubble generator 12 on the air supply pipeline L5; the compressor pump 42 is communicated with the inlet of the ejector 6 through the second branch L6; and a fifth control valve K5 is provided on the second branch L6.

[0062] Specifically, the third control valve K3 is used to control the gas supplied from the air inlet 41 to the compressor pump 42. In the embodiment of the present invention, the third control valve K3 is a check valve, also known as a non-return valve or a reflux valve. The check valve can only allow the gas from the air inlet 41 to enter the compressor pump 42, and cannot make the compressed air in the compressor pump 42 flow reversely to the air inlet 41. The compressor pump 42 compresses the gas medium provided by the air inlet 41, and supplies the compressed gas to the bubble generator 12 and the ejector 6 respectively through the air supply pipeline and the second branch L6, so that the generated bubbles are more impactful.

[0063] The fourth control valve K4 can be a solenoid valve, which is used to control the compressed gas in the compressor pump 42 to be supplied to the bubble generator 12, and the fifth control valve K5 can be a solenoid valve, which is used to control the compressed gas in the compressor pump 42 to be supplied to the ejector 6. The fourth control valve K4 and the fifth control valve K5 are both electrically connected to the system control unit, and the system control unit can control the opening and closing of the fourth control valve K4 and the fifth control valve K5. During the water purification process, the fourth control valve K4 and the fifth control valve K5 are closed; during the cleaning process, the fourth control valve K4 and the fifth control valve K5 are open.

[0064] In a possible implementation, a sixth control valve K6 is provided between the branch point of the flushing pipeline L4 and the second branch L6 and the water outlet of the cleaning water tank 3. In the embodiment of the present invention, the sixth control valve K6 is a one-way valve, which can only allow the water in the cleaning water tank 3 to enter the ejector 6, and cannot make the bubble water in the ejector 6 flow reversely to the cleaning water tank 3. This can ensure that the bubble water in the ejector 6 flushes the reverse osmosis membrane 21 more stably through the pipeline L4.

[0065] In a possible implementation, it further includes a second liquid level monitoring device 31, which is arranged in the cleaning water tank 3. The second liquid level monitoring device 31 is used to monitor the liquid level of the cleaning water tank 3, and the second high liquid level and the second low liquid level are set for the liquid level of the cleaning water tank 3. Further, the second liquid level monitoring device 31 is electrically connected to the system control unit, and the system control unit judges how to control other components based on the electrical signal of the second liquid level monitoring device 31.

[0066] Specifically, the second liquid level monitoring device 31 in the embodiment of the present invention can be a liquid level float gauge, which is composed of components such as a float and a plug rod. The second liquid level monitoring device 31 can be installed on the top of the cleaning water tank 3 through a connecting flange, convert the liquid level position into an electrical signal, and send it to the display instrument and the system control unit. The actual position of the liquid level, that is, the second liquid level monitoring device 31, is displayed digitally by the display instrument, so as to achieve remote detection and control of the liquid level.

[0067] Now, it is combined to introduce how the system control unit controls each control valve based on the first liquid level monitoring device 13 and the second liquid level monitoring device 31.

[0068] In a possible implementation, when the preset cleaning condition is not met and the first liquid level monitoring device 13 monitors that the liquid level in the filtration water tank is higher than the first middle liquid level, the system control unit controls the second control valve K2 and the fourth control valve K4 to close, so that the ultrafiltration membrane 11 purifies the liquid in the filtration water tank.

[0069] In the embodiments of the present invention, the preset cleaning condition means that when the water purification system operates for a preset operating time or the water purification stops. For example, when the water purification lasts for ten hours, the preset cleaning condition is reached. In the case where the preset cleaning condition is not met, the water purification process is carried out. The raw water is conveyed to the filter water tank. When the first liquid level monitoring device 13 detects that the water level in the filter water tank is higher than the first middle liquid level, it sends an electrical signal to the system control unit. The system control unit controls the first control valve K1 to open and the booster pump 5 to start. The negative pressure generated by the booster pump 5 provides the first working pressure for the ultrafiltration membrane 11 and the second working pressure for the reverse osmosis membrane 21, so that the reverse osmosis membrane 21 can provide sufficient osmotic pressure. And it controls the second control valve K2, the fourth control valve K4, and the fifth control valve K5 to close, that is, the purified water pipeline L2 is open, and the flushing pipeline L4 and the air inlet pipeline L5 are closed. The raw water is purified by the ultrafiltration device 1 and the reverse osmosis device 2 and flows out from the purified water outlet of the reverse osmosis device 2. Moreover, when the first liquid level monitoring device 13 detects that the water level in the filter water tank is higher than the first high liquid level, the conveyance of the raw water is stopped; when the first liquid level monitoring device 13 detects that the water level in the filter water tank is lower than the first low liquid level, the drainage is stopped, and the drainage here includes supplying water to the reverse osmosis device 2 and supplying water to the cleaning water tank 3.

[0070] In the case where the preset cleaning condition is met, when the first liquid level monitoring device 13 monitors that the liquid level in the filter water tank is not lower than the first middle liquid level, the system control unit controls the fourth control valve K4 to open, so that the gas supply device 4 provides a gas medium to the bubble generator 12 to clean the ultrafiltration membrane 11.

[0071] Specifically, when the preset cleaning condition is reached, the ultrafiltration membrane 11 is cleaned first, and then the reverse osmosis membrane 21 is cleaned. Therefore, the system control unit needs to control the first control valve K1 to close and the booster pump 5 to stop working. During cleaning, it is ensured that the liquid level in the filter water tank is not lower than the first middle liquid level. The first liquid level monitoring device 13 sends an electrical signal to the system control unit. The system control unit controls the third control valve K3 and the fourth control valve K4 to open. The gas supply device 4 provides a gas medium to the bubble generator 12. The bubble generator 12 generates bubbles below the ultrafiltration membrane 11 to clean the ultrafiltration membrane 11. If the liquid level in the filter water tank is lower than the first middle liquid level, raw water is continuously supplied to the filter water tank, and during this process, the ultrafiltration membrane 11 is still in the water purification work.

[0072] In the case where the ultrafiltration membrane 11 is cleaned until the preset cleaning time is met, when the first liquid level monitoring device 13 monitors that the liquid level in the filter water tank is not lower than the first middle liquid level, the system control unit controls the second control valve K2 to open, so that the liquid in the filter water tank flows through the booster pump 5 to the cleaning water tank 3.

[0073] Specifically, the preset cleaning time can be set according to specific circumstances, such as ten minutes, half an hour, etc. After reaching the preset cleaning time, the waste liquid obtained by cleaning the ultrafiltration membrane 11 in the filtration water tank is discharged until the liquid level in the filtration water tank is lower than the first low liquid level. Then, continue to replenish water into the filtration water tank. When the first liquid level monitoring device 13 monitors that the liquid level in the filtration water tank is not lower than the first middle liquid level, an electrical signal is sent to the system control unit. The system control unit controls the booster pump 5 to start and controls the second control valve K2 to open. The purified water filtered by the ultrafiltration membrane 11 will be replenished into the cleaning water tank 3.

[0074] Under the condition of meeting the preset cleaning conditions, when the second liquid level monitoring device 31 monitors that the liquid level in the cleaning water tank 3 is higher than the second low liquid level and lower than the second high liquid level, the system control unit controls the fifth control valve K5 to open, so that the gas supply device 4 provides a gas medium to the ejector 6 to generate bubble water for cleaning the reverse osmosis membrane 21.

[0075] Specifically, since the purified water is replenished into the cleaning water tank 3, when the second liquid level monitoring device 31 monitors that the liquid level in the cleaning water tank 3 is higher than the second low liquid level and lower than the second high liquid level, an electrical signal is sent to the system control unit. The system control unit controls the fifth control valve K5 and the sixth control valve K6 to open, so that the high-pressure gas jets towards the ejector 6. The strong pressure causes a negative pressure in the cleaning water tank 3. Then, the purified water in the cleaning water tank 3 will enter the ejector 6 at this time. In the ejector 6, it is mixed with the high-pressure gas to form bubble water with tiny bubbles. These bubble waters flow towards the reverse osmosis membrane 21 device to clean the reverse osmosis membrane 21. When the cleaning time reaches the preset cleaning time, it stops, and the waste liquid after cleaning the reverse osmosis membrane 21 in the reverse osmosis device 2 is discharged. It should be noted that when the second liquid level monitoring device 31 monitors that the liquid level in the cleaning water tank 3 reaches the second high liquid level, the water replenishment from the filtration water tank to the cleaning water tank 3 stops. When the second liquid level monitoring device 31 monitors that the liquid level in the cleaning water tank 3 is lower than the second low liquid level, the ultrafiltration device 1 continues to produce purified water and replenishes water into the cleaning water tank 3 until the liquid level in the cleaning water tank 3 is higher than the second low liquid level and lower than the second high liquid level.

[0076] In a possible implementation manner, the purified water system of the present invention further includes a first sewage discharge device 14 and a second sewage discharge device 22. The first sewage discharge device 14 is connected to the waste liquid outlet of the ultrafiltration device 1 through a first sewage discharge pipeline; a seventh control valve K7 is provided between the first sewage discharge device 14 and the ultrafiltration device 1; the second sewage discharge device 22 is connected to the waste liquid outlet of the reverse osmosis device 2 through a second sewage discharge pipeline; an eighth control valve K8 is provided between the second sewage discharge device 22 and the reverse osmosis device 2.

[0077] Specifically, the first sewage discharge device 14 is used to collect the waste liquid after cleaning the ultrafiltration membrane 11 in the filtration water tank. As described above, the filtration water tank is provided with a sewage outlet, which is arranged below the filtration water tank. In the embodiment of the present invention, the seventh control valve K7 can be a solenoid valve and is electrically connected to the system control unit; during the water purification process and when cleaning the ultrafiltration membrane 11, the seventh control valve K7 is in a closed state; when the preset cleaning time of the ultrafiltration membrane 11 is reached, the system control unit controls the seventh control valve K7 to open, and the waste liquid in the filtration water tank is discharged to the first sewage discharge device 14 through the first sewage discharge pipeline.

[0078] The second sewage discharge device 22 is used to collect the waste liquid after cleaning the reverse osmosis membrane 21 in the reverse osmosis device 2. The reverse osmosis device 2 is also provided with a sewage outlet, which is arranged below the reverse osmosis device 2. In the embodiment of the present invention, the eighth control valve K8 can be a solenoid valve and is electrically connected to the system control unit; during the water purification process and when cleaning the reverse osmosis membrane 21, the eighth control valve K8 is in a closed state; when the preset cleaning time of the reverse osmosis membrane 21 is reached, the system control unit controls the eighth control valve K8 to open, and the waste liquid in the reverse osmosis device 2 is discharged to the second sewage discharge device 22 through the second sewage discharge pipeline.

[0079] The embodiment of the present invention also provides a membrane module water purification process based on the above water purification system. When the preset cleaning conditions are not met, the water purification process includes the following steps:

[0080] S1, Supply water to the filtration water tank through the raw water supply pipeline L1 at the water inlet of the ultrafiltration device 1. When the liquid level in the filtration water tank meets the fourth preset condition, the ultrafiltration membrane 11 purifies the liquid in the filtration water tank;

[0081] S2, The liquid purified by the ultrafiltration membrane 11 flows through the water outlet of the ultrafiltration device 1 and the water inlet of the reverse osmosis device 2 through the purified water pipeline L2 and reaches the reverse osmosis device 2, where the reverse osmosis membrane 21 purifies the liquid;

[0082] S3, The liquid purified by the reverse osmosis membrane 21 flows out through the water outlet of the reverse osmosis device 2 to obtain purified water.

[0083] Specifically, as described above, the preset cleaning condition means that when the water purification system runs for a preset running time or the water purification stops. For example, when the water purification runs for ten hours, the preset cleaning condition is reached. When the preset cleaning conditions are not met, the water purification process is implemented. During the water purification process, the first control valve K1 is opened to make the purified water pipeline L2 in a conducting state; the rest of the control valves are closed to make the gas supply pipeline and the flushing pipeline L4 in a cut-off state.

[0084] Raw water is transported through the raw water supply pipeline L1 to the filtration water tank through the water inlet of the ultrafiltration device 1. In the embodiment of the present invention, the fourth preset condition means that the water level in the filtration water tank is higher than the first middle liquid level. When the first liquid level monitoring device 13 detects that the water level in the filtration water tank is higher than the first middle liquid level, it sends an electrical signal to the system control unit, and the system control unit controls the first control valve K1 to open and the booster pump 5 to start. The negative pressure generated by the booster pump 5 provides the first working pressure for the ultrafiltration membrane 11 and the second working pressure for the reverse osmosis membrane 21, so that the reverse osmosis membrane 21 can provide sufficient osmotic pressure. The raw water is purified by the ultrafiltration device 1 and the reverse osmosis device 2 and flows out from the purified water outlet of the reverse osmosis device 2. Moreover, when the first liquid level monitoring device 13 detects that the water level in the filtration water tank is higher than the first high liquid level, the supply of raw water is stopped; when the first liquid level monitoring device 13 detects that the water level in the filtration water tank is lower than the first low liquid level, the water supply to the reverse osmosis device 2 is stopped, and the raw water is continuously replenished into the filtration water tank until the water level in the filtration water tank is higher than the first middle liquid level.

[0085] The embodiment of the present invention also provides a membrane module cleaning process based on the above water purification system. When the preset cleaning conditions are met, the cleaning process includes the following steps:

[0086] S1. When the water supply to the filtration water tank through the raw water supply pipeline L1 to the water inlet of the ultrafiltration device 1 until the liquid level in the filtration water tank meets the first preset condition, the gas supply device 4 supplies a gas medium to the bubble generator 12 in the ultrafiltration device 1 through the air inlet pipeline L5. The bubble generator 12 generates bubbles in the liquid of the filtration water tank to clean the ultrafiltration membrane 11.

[0087] S2. After cleaning the ultrafiltration membrane 11 until the first preset cleaning time is reached, the waste liquid after cleaning the ultrafiltration membrane 11 in the ultrafiltration device 1 is discharged until the liquid level in the filtration water tank meets the second preset condition.

[0088] S3. Continue to replenish water into the filtration water tank through the raw water supply pipeline L1. When the liquid level in the filtration water tank meets the third preset condition, the liquid purified by the ultrafiltration membrane 11 in the filtration water tank is replenished into the cleaning water tank 3.

[0089] S4. The gas supply device 4 supplies the gas medium to the ejector 6 through the second branch L6. The ejector 6 mixes the gas medium with the liquid flowing from the cleaning water tank 3 to the ejector 6 to form bubble water.

[0090] S5. The bubble water is discharged into the reverse osmosis device 2 through the flushing pipeline L4 to clean the reverse osmosis membrane 21. After cleaning the reverse osmosis membrane 21 until the second preset cleaning time is reached, the waste liquid after cleaning the reverse osmosis membrane 21 is discharged.

[0091] Specifically, under the condition of meeting the preset cleaning conditions, the cleaning process of the membrane module is implemented. First, the ultrafiltration membrane 11 is cleaned. During the cleaning process of the ultrafiltration membrane 11, the third control valve K3 and the fourth control valve K4 are opened to make the gas supply pipeline in an open state; the rest of the control valves are closed to make the clean water pipeline L2, the flushing pipeline L4, the first branch L3 and the second branch L6 in a cut-off state, so that the water in the ultrafiltration device 1 will not flow into the reverse osmosis device 2 and the cleaning water tank 3, and the reverse osmosis membrane 21 is not cleaned when the ultrafiltration membrane 11 is cleaned.

[0092] The system control unit first controls the booster pump 5 to stop working. The first preset condition means that the liquid level in the filtration water tank is not lower than the first middle liquid level. When the first liquid level monitoring device 13 monitors that the liquid level in the filtration water tank is not lower than the first middle liquid level, it sends an electrical signal to the system control unit, and the system control unit controls the third control valve K3 and the fourth control valve K4 to open. The gas supply device 4 provides a gas medium to the bubble generator 12, and the bubble generator 12 generates bubbles below the ultrafiltration membrane 11 to clean the ultrafiltration membrane 11. If the liquid level in the filtration water tank is lower than the first middle liquid level, raw water is continuously supplied to the filtration water tank, and during this process, the ultrafiltration membrane 11 is still working for water purification until the liquid level in the filtration water tank is not lower than the first middle liquid level.

[0093] After the ultrafiltration membrane 11 is cleaned until the first preset cleaning time is reached, the system control unit controls the seventh control valve K7 to open, and the waste liquid after cleaning the ultrafiltration membrane 11 in the ultrafiltration device 1 is discharged to the first sewage disposal device 14 through the first sewage pipeline until the liquid level in the filtration water tank meets the second preset condition. The first preset cleaning time can be set according to specific conditions, such as ten minutes, half an hour, etc.; the second preset condition means that the liquid level in the filtration water tank is lower than the first low liquid level.

[0094] Then the system control unit controls the seventh control valve K7 to close, and the raw water supply pipeline L1 continues to replenish water to the filtration water tank. When the liquid level in the filtration water tank meets the third preset condition, the liquid purified by the ultrafiltration membrane 11 in the filtration water tank is replenished to the cleaning water tank 3. Among them, the third preset condition means that the liquid level in the filtration water tank is not lower than the first middle liquid level. When the first liquid level monitoring device 13 monitors that the liquid level in the filtration water tank is not lower than the first middle liquid level, it sends an electrical signal to the system control unit, and the system control unit controls the booster pump 5 to start and controls the second control valve K2 to open, conducting the first branch L3, and the purified water after passing through the ultrafiltration membrane 11 will be replenished to the cleaning water tank 3.

[0095] When the second liquid level monitoring device 31 monitors that the liquid level in the cleaning water tank 3 is higher than the second low liquid level and lower than the second high liquid level, it sends an electrical signal to the system control unit. The system control unit controls the fifth control valve K5 and the sixth control valve K6 to open, conducting the second branch L6 and the flushing pipeline L4. The gas supply device 4 supplies a gas medium to the ejector 6 through the second branch L6. The high-pressure gas will shoot towards the ejector 6, and the strong pressure causes a negative pressure in the cleaning water tank 3. Then, the purified water in the cleaning water tank 3 will enter the ejector 6 at this time, and after mixing with the high-pressure gas in the ejector 6, it forms bubble water with tiny bubbles. These bubble waters flow towards the reverse osmosis device 2 to clean the reverse osmosis membrane 21.

[0096] When the cleaning time reaches the second preset cleaning time and stops, the system control unit controls the eighth control valve K8 to open, and the waste liquid after cleaning the reverse osmosis membrane 21 in the reverse osmosis device 2 is discharged to the second sewage disposal device 22 through the second sewage pipeline. The second preset cleaning time can also be set according to specific circumstances, such as ten minutes, half an hour, etc. It should be noted that when the second liquid level monitoring device 31 monitors that the liquid level in the cleaning water tank 3 reaches the second high liquid level, the water supply from the filtering water tank to the cleaning water tank 3 stops. When the second liquid level monitoring device 31 monitors that the liquid level in the cleaning water tank 3 is lower than the second low liquid level, the ultrafiltration device 1 continues to purify water and supply water to the cleaning water tank 3 until the liquid level in the cleaning water tank 3 is higher than the second low liquid level and lower than the second high liquid level.

[0097] Through the above embodiments, the present invention can implement the water purification process and cleaning process of the ultrafiltration membrane and the reverse osmosis membrane in the water purification system. The ultrafiltration device and the reverse osmosis device are connected through a water purification pipeline for water purification; an air supply pipeline, a flushing pipeline, a first branch and a second branch are also provided for cleaning the ultrafiltration membrane and the reverse osmosis membrane. For the cleaning of the ultrafiltration membrane, the gas medium provided by the air supply device enters the bubble generator and generates a large number of bubbles in the water, and then the ultrafiltration membrane is cleaned by the bubbles and water. Compared with the commonly used hydraulic flushing, it can clean more deeply and thoroughly, and save water resources within the same cleaning time; for the cleaning of the reverse osmosis membrane, the purified water in the ultrafiltration device is used. A jet injector is set to mix the water in the cleaning water tank and the gas medium provided by the air supply device to obtain bubble water. The flushing pipeline transports the bubble water to the reverse osmosis device to flush the reverse osmosis membrane. The reverse osmosis membrane is cleaned by the bubble water. The movement and collision of small bubbles in the water generate a small range of oscillations on the reverse osmosis membrane to shake off the pollutants with strong adhesion on the membrane and in the membrane pores, and at the same time will not damage the membrane structure; and by using the adsorption effect of small bubbles, part of the pollutants on the membrane can be adsorbed into the liquid, achieving a good cleaning effect and also not damaging the membrane filaments. And the water filtered by the ultrafiltration device is used to clean the ultrafiltration membrane and the reverse osmosis membrane to ensure that the flushing water does not contain suspended particles, and at the same time remove residual trace colloids, microorganisms, etc., to avoid contaminating or damaging the membrane during the cleaning process, thereby playing a protective role for the ultrafiltration membrane and the reverse osmosis membrane.

[0098] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A water purification system, characterized in that, Comprising: An ultrafiltration device (1), a reverse osmosis device (2), a cleaning water tank (3), and a gas supply device (4); An ultrafiltration membrane (11) is provided in the filtration water tank of the ultrafiltration device (1), and a bubble generator (12) is provided below the ultrafiltration membrane (11); A reverse osmosis membrane (21) is provided in the reverse osmosis device (2); The water inlet of the ultrafiltration device (1) is communicated with the raw water supply pipeline (L1), and the water outlet of the ultrafiltration device (1) is communicated with the water inlet of the reverse osmosis device (2) through a clean water pipeline (L2); A first branch (L3) is led out from the clean water pipeline (L2) and communicated with the water inlet of the cleaning water tank (3); The water outlet of the cleaning water tank (3) is communicated with the water inlet of the reverse osmosis device (2) through a flushing pipeline (L4); A jet pump (6) is provided on the flushing pipeline (L4); The gas supply device (4) is communicated with the bubble generator (12) through an air inlet pipeline (L5); A second branch (L6) is led out from the air inlet pipeline (L5) and connected to the inlet of the jet pump (6).

2. The water purification system according to claim 1, characterized in that, A booster pump (5) is provided between the branch point of the clean water pipeline (L2) between the ultrafiltration device (1) and the first branch (L3). The first outlet of the booster pump (5) is connected to the ultrafiltration device (1) for generating a first working pressure on the ultrafiltration membrane (11); The second outlet of the booster pump (5) is connected to the reverse osmosis device (2) for generating a second working pressure on the reverse osmosis membrane (21); A first control valve (K1) is provided on the clean water pipeline (L2) between the branch point of the first branch (L3) and the water inlet of the reverse osmosis device (2); A second control valve (K2) is provided on the first branch (L3).

3. The water purification system according to claim 1, characterized in that, The gas supply device (4) includes an air inlet (41), a gas compressor pump (42), and a third control valve (K3), and the third control valve (K3) is provided between the air inlet (41) and the gas compressor pump (42); The gas compressor pump (42) is communicated with the bubble generator (12) through the air inlet pipeline (L5); A fourth control valve (K4) is provided on the air inlet pipeline (L5) between the branch point of the second branch (L6) and the bubble generator (12); The gas compressor pump (42) is communicated with the inlet of the jet pump (6) through the second branch (L6); A fifth control valve (K5) is provided on the second branch (L6).

4. The water purification system according to claim 1, characterized in that A sixth control valve (K6) is provided on the flushing pipeline (L4) between the branch point of the second branch (L6) and the water outlet of the cleaning water tank (3).

5. The water purification system according to claim 1, characterized in that It further includes a first liquid level monitoring device (13), the first liquid level monitoring device (13) is provided in the filtration water tank, the first liquid level monitoring device (13) is used to monitor the liquid level of the filtration water tank, and the liquid level of the filtration water tank is set with a first high liquid level, a first medium liquid level, and a first low liquid level.

6. The water purification system according to claim 1, characterized in that, It further includes a second liquid level monitoring device (31). The second liquid level monitoring device (31) is arranged in the cleaning water tank (3). The second liquid level monitoring device (31) is used to monitor the liquid level of the cleaning water tank (3). The liquid level of the cleaning water tank (3) is set with a second high liquid level and a second low liquid level.

7. The water purification system according to claim 5, wherein The first liquid level monitoring device (13) is electrically connected to the system control unit, and the second control valve (K2) and the fourth control valve (K4) are both electrically connected to the system control unit; When the liquid level in the filtration water tank monitored by the first liquid level monitoring device (13) is higher than the first middle liquid level under the condition that the preset cleaning conditions are not met, the system control unit controls the second control valve (K2) and the fourth control valve (K4) to close, so that the ultrafiltration membrane (11) purifies the liquid in the filtration water tank; When the liquid level in the filtration water tank monitored by the first liquid level monitoring device (13) is not lower than the first middle liquid level under the condition that the preset cleaning conditions are met, the system control unit controls the fourth control valve (K4) to open, so that the gas supply device (4) provides the gas medium to the bubble generator (12) to clean the ultrafiltration membrane (11); When the cleaning of the ultrafiltration membrane (11) reaches the preset cleaning time and the liquid level in the filtration water tank monitored by the first liquid level monitoring device (13) is not lower than the first middle liquid level, the system control unit controls the second control valve (K2) to open, so that the liquid in the filtration water tank flows through the booster pump (5) into the cleaning water tank (3).

8. The water purification system according to claim 6, characterized in that, The second liquid level monitoring device (31) is electrically connected to the system control unit, and the fifth control valve (K5) is electrically connected to the system control unit; When the liquid level in the cleaning water tank (3) monitored by the second liquid level monitoring device (31) is higher than the second low liquid level and lower than the second high liquid level under the condition that the preset cleaning conditions are met, the system control unit controls the fifth control valve (K5) to open, so that the gas supply device (4) provides the gas medium to the ejector (6) to generate bubble water to clean the reverse osmosis membrane (21).

9. The water purification system according to claim 1, characterized in that, It further includes: A first sewage discharge device (14). The first sewage discharge device (14) is connected to the waste liquid outlet of the ultrafiltration device (1) through a first sewage discharge pipeline; a seventh control valve (K7) is arranged between the first sewage discharge device (14) and the ultrafiltration device (1); A second sewage discharge device (22). The second sewage discharge device (22) is connected to the waste liquid outlet of the reverse osmosis device (2) through a second sewage discharge pipeline; an eighth control valve (K8) is arranged between the second sewage discharge device (22) and the reverse osmosis device (2).

10. The membrane module cleaning process of the water purification system according to any one of claims 1 to 9, characterized in that, Under the condition that the preset cleaning conditions are met, the cleaning process includes the following steps: When water is supplied to the filtration water tank through the inlet of the ultrafiltration device (1) via the raw water supply pipeline (L1) until the liquid level in the filtration water tank meets the first preset condition, the gas supply device (4) supplies a gas medium to the bubble generator (12) in the ultrafiltration device (1) through the gas inlet pipeline (L5), and the bubble generator (12) generates bubbles in the liquid of the filtration water tank to clean the ultrafiltration membrane (11). After cleaning the ultrafiltration membrane (11) until the first preset cleaning time is reached, the waste liquid after cleaning the ultrafiltration membrane (11) in the ultrafiltration device (1) is discharged until the liquid level in the filtration water tank meets the second preset condition. Water is continuously replenished into the filtration water tank through the raw water supply pipeline (L1). When the liquid level in the filtration water tank meets the third preset condition, the liquid purified by the ultrafiltration membrane (11) in the filtration water tank is replenished into the cleaning water tank (3). The gas supply device (4) supplies the gas medium to the ejector (6) through the second branch (L6), and the ejector (6) mixes the gas medium with the liquid flowing from the cleaning water tank (3) to the ejector (6) to form bubble water. The bubble water is discharged into the reverse osmosis device (2) through the flushing pipeline (L4) to clean the reverse osmosis membrane (21). After cleaning the reverse osmosis membrane (21) until the second preset cleaning time is reached, the waste liquid after cleaning the reverse osmosis membrane (21) is discharged.

11. The membrane module water purification process of the water purification system according to any one of claims 1 to 9, characterized in that, In the case where the preset cleaning conditions are not met, the water purification process includes the following steps: Water is supplied to the filtration water tank through the inlet of the ultrafiltration device (1) via the raw water supply pipeline (L1). When the liquid level in the filtration water tank meets the fourth preset condition, the ultrafiltration membrane (11) purifies the liquid in the filtration water tank. The liquid purified by the ultrafiltration membrane (11) flows through the outlet of the ultrafiltration device (1) and the inlet of the reverse osmosis device (2) through the purified water pipeline (L2) and reaches the reverse osmosis device (2), where the reverse osmosis membrane (21) purifies the liquid. The liquid purified by the reverse osmosis membrane (21) flows out through the outlet of the reverse osmosis device (2) to obtain purified water.

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