Ultrafiltration and nanofiltration double membrane method drinking water treatment device
By using ultrasonic cleaning components and physical backwashing technology, the problems of membrane component fouling and poor cleaning effect in ultrafiltration and nanofiltration dual-membrane purification equipment have been solved, achieving efficient and low-cost membrane component cleaning and long-term stable operation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YANGTZE DELTA REGION INST OF TSINGHUA UNIV ZHEJIANG
- Filing Date
- 2026-03-27
- Publication Date
- 2026-05-29
AI Technical Summary
Existing ultrafiltration and nanofiltration dual-membrane purification equipment is prone to membrane fouling, has poor cleaning effect, and high operation and maintenance costs during long-term operation. Traditional cleaning methods can easily damage the membrane structure and may produce chemical residues.
An ultrasonic cleaning module combined with physical backwashing technology is used to clean ultrafiltration and nanofiltration membranes using 28kHz low-frequency and 40kHz high-frequency ultrasonic waves. This, along with a pressure buffer tank and a backwash storage tank, achieves efficient cleaning of the membrane modules and avoids damage and chemical residues caused by chemical cleaning.
It significantly extends the service life of membrane modules, reduces operation and maintenance costs, improves water quality stability and treatment efficiency, simplifies operation processes, and avoids secondary pollution.
Smart Images
Figure CN122102296A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of water treatment technology, specifically to a dual-membrane drinking water treatment device using ultrafiltration and nanofiltration. Background Technology
[0002] Direct drinking water refers to high-quality drinking water that can be consumed directly without boiling. Its quality must strictly comply with the relevant requirements of the national standards for drinking water quality and drinking water purification standards. It must not only thoroughly remove visible impurities such as suspended solids, colloids, and sediment, but also kill pathogenic microorganisms such as bacteria and viruses, and deeply remove heavy metal ions, toxic components, and trace organic pollutants. It is generally used for daily healthy drinking water in high-standard residential areas and new rural areas, as well as commercial water purification in large shopping malls and tourist areas, and is suitable for long-term use in fixed locations. While traditional tap water treatment processes meet direct drinking water standards at the treatment plant, the instability of the distribution network can lead to contamination, leakage, and excessive bacteria levels by the time the tap water reaches the point of sale, making it difficult to reliably guarantee the safety of direct drinking water. Therefore, deep purification equipment is usually installed at direct drinking water supply points to further purify the tap water source.
[0003] Existing ultrafiltration and nanofiltration dual-membrane purification equipment is a drinking water deep treatment process that combines ultrafiltration (UF) and nanofiltration (NF) in series. Ultrafiltration is used as the front-end pretreatment. The ultrafiltration permeate then enters the nanofiltration unit. With the help of the selective separation capability of nanofiltration membranes for small molecules and ions, hardness ions, heavy metals, trace organic matter and some dissolved salts in the water are deeply removed, achieving water softening and purification. Through staged treatment and synergistic effect, it retains the advantages of ultrafiltration such as low operating pressure, high flux and strong anti-fouling ability, and also gives full play to the characteristics of nanofiltration such as high precision and good selectivity. The whole process is physical separation, without secondary pollution from chemical agents, and the effluent is highly safe. It is a commonly used water purification equipment.
[0004] However, during long-term operation, pollutants tend to adhere to and accumulate on the membrane surface of existing ultrafiltration and nanofiltration dual-membrane purification equipment, causing membrane pore blockage, reduced permeate flux, and water quality fluctuations. Traditional membrane cleaning methods mostly employ hydraulic backwashing or chemical cleaning. Hydraulic backwashing is ineffective at removing stubborn pollutants, while chemical cleaning not only damages the membrane fiber structure and shortens the membrane's lifespan but also easily produces chemical residues that pollute the water. Furthermore, the cleaning process is cumbersome and the maintenance costs are high, which greatly limits the long-term stable operation of the dual-membrane process and leaves room for further improvement. Summary of the Invention
[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an ultrafiltration-nanofiltration dual-membrane drinking water treatment device, which solves the problems of easy fouling of membrane modules, poor cleaning effect, and high operation and maintenance costs of existing equipment.
[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: an ultrafiltration and nanofiltration dual-membrane drinking water treatment device, comprising a base and a frame, wherein the frame is fixedly connected above the base, an inlet pipe is fixedly connected to the lower side of one side of the frame, an outlet pipe is fixedly connected to the lower side of the frame away from the inlet pipe, an outlet valve is provided at the outlet end of the outlet pipe, a plurality of ultrafiltration chambers are equidistantly arranged above the inlet pipe on the frame, each of the plurality of ultrafiltration chambers is provided with an ultrasonic cleaning assembly for ultrafiltration membranes, a plurality of nanofiltration chambers are equidistantly arranged above the outlet pipe on the frame, each of the plurality of nanofiltration chambers is provided with an ultrasonic cleaning assembly for nanofiltration membranes on the inner wall of the plurality of nanofiltration chambers, a connecting pipe is fixedly connected above each of the plurality of ultrafiltration chambers, a backwashing pipe is fixedly connected to the upper middle part of the frame, and a waste discharge pipe is fixedly connected to the end of the backwashing pipe away from the outlet valve; A pressure buffer tank is fixedly connected to the upper center of the base at the end away from the waste discharge pipe. A pressure pump is fixedly connected to the inlet of the pressure buffer tank, and a main valve is fixedly connected to the inlet of the pressure pump. The outlet of the pressure buffer tank is fixedly connected to the backwash pipe and the inlet pipe through a water distribution pipe. A backwash valve and an inlet valve are respectively installed at the inlet of the backwash pipe and the inlet pipe. A backwash pressure storage tank is fixedly connected to the upper center of the base at the end away from the pressure buffer tank.
[0007] Preferably, the upper part of each of the multiple connecting pipes is fixedly connected to the lower part of the backwashing pipe, and a connecting valve is provided at the end of each of the multiple connecting pipes near the ultrafiltration chamber.
[0008] Preferably, the ultrafiltration chamber is provided with a hollow fiber ultrafiltration membrane, and the nanofiltration chamber is provided with a hollow tubular ceramic nanofiltration membrane.
[0009] Preferably, the ultrasonic cleaning assembly for the ultrafiltration membrane includes multiple piezoelectric ceramic transducers using a low frequency of 28kHz and a power of 80W per unit. Four of the multiple piezoelectric ceramic transducers are arranged in a 90° equidistant array along the inner wall of the ultrafiltration chamber, with each array having an axial spacing of 400mm. The piezoelectric ceramic transducers are directly immersed in water, with the ultrasonic transmitting end facing the effective filtration section of the membrane fiber. The assembly operates intermittently, with a single operation lasting 3 minutes and an interval of 30 minutes.
[0010] Preferably, the nanofiltration membrane ultrasonic cleaning assembly is provided with four 40kHz high-frequency piezoelectric ceramic transducer arrays per group, each with a power of 50W, and the four transducer arrays in each group are equidistantly arranged at 90° intervals on the inner wall of the nanofiltration chamber.
[0011] Preferably, the ends of the backwash pipe, inlet pipe, and outlet pipe that are away from the pressure buffer tank are all fixedly connected to the waste discharge pipe, and the ends of the backwash pipe, inlet pipe, and outlet pipe that are close to the waste discharge pipe are all equipped with waste discharge valves.
[0012] Preferably, a pressure storage chamber is provided at the top of the backwash pressure tank, and the bottom of the backwash pressure tank is fixedly connected to the water outlet pipe.
[0013] Preferably, reinforcing hoops are fixedly fitted onto the outer walls of the ultrafiltration chamber and nanofiltration chamber at positions corresponding to the transducer array.
[0014] (III) Beneficial Effects This invention provides a dual-membrane drinking water treatment device using ultrafiltration and nanofiltration. It has the following beneficial effects: 1. This invention includes an ultrasonic cleaning module for ultrafiltration membranes and an ultrasonic cleaning module for nanofiltration membranes. Through the targeted application of 28kHz low-frequency ultrasound and 40kHz high-frequency ultrasound, stubborn contaminants on the membrane surface can be efficiently removed, avoiding damage to the membrane structure caused by traditional chemical cleaning. This significantly extends the service life of both ultrafiltration and nanofiltration membranes, reducing membrane module replacement costs. Simultaneously, the pressure buffer tank balances the inlet water pressure, preventing water pressure fluctuations from impacting the membrane modules and improving treatment efficiency and effluent water quality stability. Furthermore, the dual-membrane process combines ultrasonic cleaning and physical backwashing, eliminating the need for chemical agents, thus avoiding secondary contamination, simplifying maintenance procedures, and reducing daily operating costs.
[0015] 2. The present invention features a coordinated design of a backwash pressure tank and a backwash pipeline. When the outlet valve is closed, the pressure of the booster pump can be directly utilized through the air chamber pressure storage method to provide a stable backwash pressure. There is no need to set up a separate backwash pump. It can be used in conjunction with ultrasonic cleaning to achieve deep cleaning, effectively restore membrane flux, and ensure long-term stable operation of the equipment at low cost. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the left-side three-dimensional structure of the present invention; Figure 2 This is a three-dimensional structural diagram of the right side of the present invention; Figure 3 This is a schematic diagram of the internal structure of the ultrafiltration chamber of the present invention; Figure 4 This is a schematic diagram of the internal structure of the nanofiltration chamber of the present invention.
[0017] The components are as follows: 1. Base; 2. Frame; 3. Inlet pipe; 4. Booster pump; 5. Main valve; 6. Pressure buffer tank; 7. Ultrafiltration chamber; 8. Connecting pipe; 9. Nanofiltration chamber; 10. Outlet pipe; 11. Distribution pipe; 12. Backwash pipe; 13. Ultrafiltration membrane ultrasonic cleaning assembly; 14. Nanofiltration membrane ultrasonic cleaning assembly; 15. Backwash pressure tank; 16. Waste discharge pipe; 17. Inlet valve; 18. Outlet valve; 19. Waste discharge valve; 20. Backwash valve; 21. Connecting valve. Detailed Implementation
[0018] The technical solutions of the embodiments of the present invention will now be described in conjunction with the accompanying drawings. The embodiments described herein are clearly and completely presented. Obviously, the described embodiments are only a portion of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0019] Example 1: like Figure 1-4As shown, this embodiment of the invention provides an ultrafiltration-nanofiltration dual-membrane drinking water treatment device, including a base 1 and a frame 2. The frame 2 is fixedly connected to the top of the base 1. An inlet pipe 3 is fixedly connected to the lower side of one side of the frame 2. An outlet pipe 10 is fixedly connected to the lower side of the frame 2 away from the inlet pipe 3. An outlet valve 18 is provided at the outlet end of the outlet pipe 10. Multiple ultrafiltration chambers 7 are equidistantly arranged above the inlet pipe 3 on the frame 2. Hollow fiber ultrafiltration membranes are arranged inside the ultrafiltration chambers 7. Each of the multiple ultrafiltration chambers 7 is equipped with a hollow fiber ultrafiltration membrane. The system includes an ultrafiltration membrane ultrasonic cleaning assembly 13. A frame 2 has multiple nanofiltration chambers 9 equidistantly arranged above the outlet pipe 10. Hollow tubular ceramic nanofiltration membranes are installed inside each nanofiltration chamber 9. The ultrafiltration membrane ultrasonic cleaning assembly 13 includes multiple piezoelectric ceramic transducers using a 28kHz low-frequency, 80W power unit. Four piezoelectric ceramic transducers are arranged in a 90° equidistant array along the inner wall of each ultrafiltration chamber 7, with an axial spacing of 400mm between each array. Nanofiltration membrane ultrasonic cleaning assemblies 14 are installed on the inner walls of each of the multiple nanofiltration chambers 9. The nanofiltration membrane ultrasonic cleaning assembly 14 is equipped with four 40kHz high-frequency piezoelectric ceramic transducer arrays, each with a power of 50W. Each group of four transducer arrays is equidistantly positioned at 90° intervals on the inner wall of the nanofiltration chamber 9. Reinforcing hoops are fixedly fitted onto the outer walls of both the ultrafiltration chamber 7 and the nanofiltration chamber 9 at positions corresponding to the transducer arrays to enhance the strength of the filter chambers and facilitate power connection to the transducers. This ultrasonic cleaning assembly can precisely target the fouling characteristics of both ultrafiltration and nanofiltration membranes. The 28kHz low-frequency ultrasound generates a strong cavitation effect, effectively stripping large molecular pollutants such as colloids and suspended solids from the surface of the ultrafiltration membrane. The 40kHz high-frequency ultrasound is more suitable for decomposing small molecule organic pollutants and ionic deposits on the nanofiltration membrane. The combination of ultrasonic cleaning at these two frequencies with physical backwashing achieves deep cleaning of the membrane assembly, significantly improving cleaning efficiency and effectiveness. Furthermore, the intermittent operation mode ensures cleaning effectiveness while avoiding unnecessary wear on the membrane fibers caused by continuous ultrasound, further extending the service life of the membrane assembly. Multiple ultrafiltration chambers 7 are fixedly connected to the top of each other by connecting pipes 8. A backwash pipe 12 is fixedly connected to the middle of the upper part of the frame 2. The upper part of each of the multiple connecting pipes 8 is fixedly connected to the lower part of the backwash pipe 12. A connecting valve 21 is installed at the end of each of the multiple connecting pipes 8 near the ultrafiltration chamber 7. A waste discharge pipe 16 is fixedly connected to the end of the backwash pipe 12 away from the outlet valve 18. The ends of the backwash pipe 12, the inlet pipe 3, and the outlet pipe 10 away from the pressure buffer tank 6 are all fixedly connected to the waste discharge pipe 16. A waste discharge valve 19 is installed at the end of the backwash pipe 12, the inlet pipe 3, and the outlet pipe 10 near the waste discharge pipe 16. The inlet ends of the backwash pipe 12 and the inlet pipe 3 are respectively... The system is equipped with a backwash valve 20 and an inlet valve 17. A backwash pressure tank 15 is fixedly connected to the middle of the upper part of the base 1, away from the pressure buffer tank 6. A pressure storage chamber is set inside the backwash pressure tank 15. The lower part of the backwash pressure tank 15 is fixedly connected to the outlet pipe 10. The backwash pipe 12 works in conjunction with the backwash pressure tank 15. With the pressure of the pressure storage chamber, deep cleaning can be completed without an additional backwash pump. The waste discharge pipe 16 is used to discharge cleaning wastewater and empty the system. The inlet valve 17, outlet valve 18, backwash valve 20, waste discharge valve 19 and other valves on each pipe can flexibly adjust the water flow direction and system operating conditions to ensure stable operation of the device in purification, cleaning and other modes. A pressure buffer tank 6 is fixedly connected to the upper middle part of the end of the base 1 away from the waste discharge pipe 16. The inlet end of the pressure buffer tank 6 is fixedly connected to a booster pump 4, and the inlet end of the booster pump 4 is fixedly connected to a main valve 5. The outlet end of the pressure buffer tank 6 is fixedly connected to the backwash pipe 12 and the inlet pipe 3 through the water distribution pipe 11. The pressure buffer tank 6, together with the booster pump 4, can provide water pressure while ensuring that the pressure fluctuation is smooth, thereby reducing damage to the membrane module.
[0020] Working Principle: During operation, the ultrafiltration chamber 7 and nanofiltration chamber 9 are arranged in an orderly manner on the frame 2. The inlet pipe 3 is connected to the pressure buffer tank 6 through the water distribution pipe 11. When the membrane module needs cleaning, simply close the outlet valve 18 to allow the backwash pressure tank 15 to accumulate pressure through the pressurization pump 4. When the pressure is sufficient, close the connecting valve 21 and open the waste discharge valve 19 corresponding to the backwash pipe 12. The pressure storage chamber in the backwash pressure tank 15 provides backwash pressure. At the same time, the nanofiltration membrane ultrasonic cleaning component 14 is activated to backwash the nanofiltration chamber 9. After the nanofiltration backwash is completed, open the connecting valve 21 and the ultrafiltration membrane ultrasonic cleaning component 13 to perform ultrafiltration membrane cleaning. High-frequency ultrasound removes contaminants from the membrane surface, and the cleaning wastewater is discharged through the waste discharge pipe 16. This achieves an organic combination of high-efficiency purification and low-damage cleaning, ensuring long-term stable operation of the device.
[0021] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A dual-membrane drinking water treatment device using ultrafiltration and nanofiltration, comprising a base (1) and a frame (2), characterized in that: A frame (2) is fixedly connected above the base (1). A water inlet pipe (3) is fixedly connected to the lower side of one side of the frame (2). A water outlet pipe (10) is fixedly connected to the lower side of the frame (2) away from the water inlet pipe (3). A water outlet valve (18) is provided at the water outlet end of the water outlet pipe (10). Multiple ultrafiltration chambers (7) are equidistantly arranged above the water inlet pipe (3) on the frame (2). Each of the multiple ultrafiltration chambers (7) is equipped with an ultrafiltration membrane ultrasonic cleaning assembly. (13) The frame (2) is provided with multiple nanofiltration chambers (9) at equal intervals above the water outlet pipe (10). Each of the multiple nanofiltration chambers (9) is provided with a nanofiltration membrane ultrasonic cleaning assembly (14). Each of the multiple ultrafiltration chambers (7) is fixedly connected to a connecting pipe (8). A backwash pipe (12) is fixedly connected to the middle of the upper part of the frame (2). A waste discharge pipe (16) is fixedly connected to the end of the backwash pipe (12) away from the water outlet valve (18). A pressure buffer tank (6) is fixedly connected to the middle of the upper part of the base (1) away from the waste discharge pipe (16). A booster pump (4) is fixedly connected to the water inlet of the pressure buffer tank (6). A main valve (5) is fixedly connected to the water inlet of the booster pump (4). The water outlet of the pressure buffer tank (6) is fixedly connected to the backwash pipe (12) and the water inlet pipe (3) respectively through the water distribution pipe (11). A backwash valve (20) and a water inlet valve (17) are respectively provided at the water inlet of the backwash pipe (12) and the water inlet pipe (3). A backwash pressure storage tank (15) is fixedly connected to the middle of the upper part of the base (1) away from the pressure buffer tank (6).
2. The ultrafiltration-nanofiltration dual-membrane drinking water treatment device according to claim 1, characterized in that: The upper part of each of the multiple connecting pipes (8) is fixedly connected to the lower part of the backwash pipe (12), and a connecting valve (21) is provided at one end of each of the multiple connecting pipes (8) near the ultrafiltration chamber (7).
3. The ultrafiltration-nanofiltration dual-membrane drinking water treatment device according to claim 1, characterized in that: The ultrafiltration chamber (7) is equipped with a hollow fiber ultrafiltration membrane, and the nanofiltration chamber (9) is equipped with a hollow tube ceramic nanofiltration membrane.
4. The ultrafiltration-nanofiltration dual-membrane drinking water treatment device according to claim 1, characterized in that: The ultrasonic cleaning assembly (13) for ultrafiltration membrane includes multiple piezoelectric ceramic transducer arrays with a low frequency of 28kHz and a power of 80W per unit. Each array has four piezoelectric ceramic transducers arranged at equal intervals of 90° along the inner wall of the ultrafiltration chamber (7), and the axial spacing of each array is 400mm.
5. The ultrafiltration-nanofiltration dual-membrane drinking water treatment device according to claim 1, characterized in that: The nanofiltration membrane ultrasonic cleaning assembly (14) is equipped with four 40kHz high-frequency piezoelectric ceramic transducer arrays per group, each with a power of 50W, and the four transducer arrays in each group are equidistantly arranged at 90° intervals on the inner wall of the nanofiltration chamber (9).
6. The ultrafiltration-nanofiltration dual-membrane drinking water treatment device according to claim 1, characterized in that: The backwash pipe (12), water inlet pipe (3) and water outlet pipe (10) are all fixedly connected to the waste discharge pipe (16) at the end away from the pressure buffer tank (6), and a waste discharge valve (19) is provided at the end of the backwash pipe (12), water inlet pipe (3) and water outlet pipe (10) near the waste discharge pipe (16).
7. The ultrafiltration-nanofiltration dual-membrane drinking water treatment device according to claim 1, characterized in that: The backwash pressure tank (15) has a pressure storage chamber at the top inside, and the bottom of the backwash pressure tank (15) is fixedly connected to the water outlet pipe (10).
8. A dual-membrane drinking water treatment device using ultrafiltration and nanofiltration according to claim 4 or 5, characterized in that: The outer walls of the ultrafiltration chamber (7) and nanofiltration chamber (9) are fixedly fitted with reinforcing hoops at positions corresponding to the transducer array.