CN118579897A - An electrodialysis process pretreatment test device and process - Google Patents

Abstract

The present invention provides an electrodialysis process pretreatment test device and process, belonging to the field of environmental engineering water treatment technology, wherein the test device includes an ultrafiltration unit and a nanofiltration unit; the ultrafiltration unit includes an ultrafiltration lift pump, an ultrafiltration raw water tank, an ultrafiltration module and an ultrafiltration water production tank; the ultrafiltration lift pump is connected to the ultrafiltration raw water tank, and is used to transport the water to be treated to the ultrafiltration raw water tank; the nanofiltration unit includes a nanofiltration lift pump, a nanofiltration module and a nanofiltration water production tank. The ultrafiltration unit of the present invention adopts an ultrafiltration inorganic membrane and an ultrafiltration organic membrane in parallel, and then the ultrafiltration unit is connected in series with the nanofiltration unit. When in use, the ultrafiltration mode of the ultrafiltration unit can be switched, so that the ultrafiltration organic membrane and the ultrafiltration inorganic membrane have a horizontal comparison function of the treatment effect, and the nanofiltration unit can be used in combination, which effectively solves the problems of resin pollution and regeneration efficiency, and the treatment cost is low and the sludge amount is reduced.

Description

An electrodialysis process pretreatment test device and process

Technical Field

The invention belongs to the technical field of environmental engineering water treatment, and in particular relates to an electrodialysis process pretreatment test device and process.

Background Art

As an electro-membrane desalination process, electrodialysis has relatively mature industrial applications in pharmaceutical purification and food concentration. The application of this technology in petroleum and petrochemical enterprises has also been a research focus in recent years. Applying this technology in unconventional oil and gas development can effectively improve the desalination efficiency of salt water and achieve concentrated water reduction.

The electrodialysis process has the advantages of simple operation, wide applicable water salinity range, and good effluent effect, but it also has the disadvantages of easy membrane pollution, only removing charged ions, and being easily polluted by colloidal substances. Due to the pollution characteristics of ion exchange membranes, the electrodialysis process is sensitive to suspended matter, high-valent ions such as hardness ions, and oil.

For the removal of suspended solids, oil, hardness ions and other substances in sewage, the current pretreatment process is generally a simple treatment through physical and chemical methods. Add flocculants to condense the suspended solids in the sewage, and then remove the large molecular weight substances by sedimentation or filtration, or use the electro-flocculation process to form hydroxide complexes to adsorb and remove suspended solids and oil in the water. The use of ultrafiltration membrane filtration technology can also remove the above impurities, creating good reaction conditions for subsequent treatment processes. The main method for removing hardness ions is the agent softening method, but the treatment cost is high and the amount of sludge is large. Ion exchange resins can remove hardness and solve the problem of sludge generation, but the problems of resin pollution and regeneration efficiency still exist.

Summary of the invention

In view of the above problems, the present invention proposes an electrodialysis process pretreatment test device and process.

In order to achieve the above object, the present invention adopts the following technical solutions:

An electrodialysis process pretreatment test device comprises an ultrafiltration unit and a nanofiltration unit;

The ultrafiltration unit includes an ultrafiltration lift pump, an ultrafiltration raw water tank, an ultrafiltration module and an ultrafiltration water production tank; the ultrafiltration lift pump is connected to the ultrafiltration raw water tank and is used to transport the water to be treated to the ultrafiltration raw water tank;

The ultrafiltration raw water tank is connected to an ultrafiltration module, and the ultrafiltration module is used to ultrafilter the water to be treated and transport the ultrafiltered water to the ultrafiltration water production tank;

The ultrafiltration module is connected to an ultrafiltration water production tank, and the ultrafiltration water production tank is connected to a nanofiltration unit and a drain outlet;

The nanofiltration unit includes a nanofiltration lift pump, a nanofiltration module and a nanofiltration water production tank;

The nanofiltration lift pump is connected to the nanofiltration module, and is used to receive the water to be treated and/or the ultrafiltered water delivered by the ultrafiltration water production tank, and deliver the water to be treated and/or the ultrafiltered water to the nanofiltration module;

The nanofiltration module is connected to the nanofiltration water production tank, and is used to perform nanofiltration on the treated water and/or the water after ultrafiltration, and to transport the water after nanofiltration to the nanofiltration water production tank, and the nanofiltration water production tank is also connected to the drain port.

Preferably, the ultrafiltration module comprises a first pipeline and a second pipeline arranged in parallel;

The first pipeline is provided with an organic membrane circulation pump and an ultrafiltration organic membrane connected in sequence;

The ultrafiltration organic membrane is connected to the ultrafiltration water production tank and the drain outlet;

The ultrafiltration organic membrane is also connected to the ultrafiltration raw water tank to return the concentrated water to the ultrafiltration raw water tank;

The second pipeline is provided with an inorganic membrane circulation pump and an ultrafiltration inorganic membrane connected in sequence;

The ultrafiltration inorganic membrane is connected to the ultrafiltration water production tank and the drain outlet;

The ultrafiltration inorganic membrane is also connected to the ultrafiltration raw water tank and is used to return concentrated water to the ultrafiltration raw water tank.

Preferably, the ultrafiltration water production tank is also connected to an ultrafiltration backwash pump; the ultrafiltration backwash pump is used to transport water to the ultrafiltration organic membrane and the ultrafiltration inorganic membrane for water washing.

Preferably, it also includes an air compressor and an air storage tank, wherein the air compressor is connected to the air storage tank, and the air storage tank is connected to the ultrafiltration inorganic membrane for air washing the ultrafiltration inorganic membrane.

Preferably, the nanofiltration module comprises a nanofiltration raw water tank, a water supply pump, a security filter, a high-pressure pump and an ion separation membrane connected in sequence;

The ion separation membrane is also connected to the nanofiltration raw water tank for concentrated water reflux.

Preferably, the nanofiltration raw water tank is also connected to a nanofiltration lift pump; and the ion separation membrane is connected to a nanofiltration produced water tank.

Preferably, the nanofiltration water production tank is also connected to a nanofiltration cleaning pump, and the nanofiltration cleaning pump is connected to the ion separation membrane for washing the ion separation membrane with water.

An electrodialysis process pretreatment process is used for the above-mentioned electrodialysis process pretreatment test device. The process includes the following working steps:

Perform ultrafiltration or nanofiltration on the water to be treated;

Discharge the water after ultrafiltration treatment or perform nanofiltration treatment;

The water treated by nanofiltration is discharged.

Preferably, the water to be treated is subjected to ultrafiltration treatment, comprising:

Ultrafiltration of the water to be treated using an ultrafiltration organic membrane, and/or, ultrafiltration of the water to be treated using an ultrafiltration inorganic membrane;

The water to be treated and/or the water after ultrafiltration treatment is subjected to nanofiltration using an ion separation membrane.

Preferably, the process comprises an ultrafiltration unit cleaning step:

Firstly, water is added to the ultrafiltration raw water tank to prepare a cleaning solution, wherein the cleaning solution is a NaOH solution with a concentration of 0.5%;

Clean the ultrafiltration organic membrane. After the cleaning liquid circulates in the pretreatment test device for 30 minutes, the liquid in the device is emptied;

Clean the inorganic ultrafiltration membrane. After the cleaning liquid circulates in the pretreatment test device for 30 minutes, the liquid in the device is emptied;

Add fresh water to the ultrafiltration raw water tank, run the pretreatment test device until the pH is neutral, check the water production, if the difference between the fresh water production rate and the fresh water production rate obtained by the first test under the same conditions is within 10%, stop chemical cleaning, if it exceeds 10%, use acid solution to perform chemical cleaning again;

Prepare 0.5% hydrochloric acid solution in the ultrafiltration raw water tank and repeat the above steps for chemical cleaning until the fresh water production rate is within 10% of the value measured under the same conditions.

Preferably, the process comprises a nanofiltration unit cleaning step:

A NaOH solution with a concentration of 0.1% is prepared in the nanofiltration water production tank;

Start the nanofiltration cleaning pump, and let the cleaning liquid circulate in the system for 10 minutes. Then turn off the nanofiltration cleaning pump and completely immerse the ion separation membrane in the cleaning liquid. After 10 minutes, start the nanofiltration cleaning pump, and after running for 10 minutes, turn off the nanofiltration cleaning pump, and then drain the liquid in the nanofiltration water production tank.

Add fresh water to the nanofiltration raw water tank and start the device operation mode until the pH of the produced water is close to neutral. Check the water production. If the difference between the fresh water production rate and the fresh water production rate obtained by the first test under the same conditions is within 10%, stop chemical cleaning. If it exceeds 10%, use acid solution for chemical cleaning again.

A 0.1% hydrochloric acid solution was prepared in the nanofiltration water production tank, and the above steps were repeated for chemical cleaning until the fresh water production rate was within 10% of the value measured under the same conditions.

Beneficial effects of the present invention:

1. The ultrafiltration unit of the present invention adopts an ultrafiltration inorganic membrane and an ultrafiltration organic membrane in parallel, and then the ultrafiltration unit is connected in series with a nanofiltration unit. The ultrafiltration mode of the ultrafiltration unit can be switched during use, so that the ultrafiltration organic membrane and the ultrafiltration inorganic membrane have a horizontal comparison function of treatment effect, and can be used in combination with a nanofiltration unit, effectively solving the problems of resin pollution and regeneration efficiency, and the treatment cost is low and the amount of sludge is reduced;

2. The patent of the present invention can effectively reduce the concentration of high-valent ions such as suspended solids, colloids, biomass, oil, hardness ions, etc. as a pretreatment process to provide high-quality water inlet conditions for the electrodialysis process, and can also provide a high-quality treatment solution for the purification and separation of substances with relatively single anions and cations;

3. The invention patent of this invention, as a laboratory-scale device, has a high degree of automation, is equipped with multiple solenoid valves and interlocking controls, and is relatively simple to operate. The water inlet, each unit connection port, and the water outlet interface are standard-sized quick-release chucks, which lays a good equipment foundation for the subsequent improvement of the process chain and can achieve rapid connection;

4. The sizes of the ultrafiltration organic membrane and ion separation membrane components of the present invention can be connected with the international standard sizes, so that the device can replace membrane products of different brands and parameters according to experimental requirements, and realize the comparison of the treatment effects of ultrafiltration organic membrane and inorganic membrane in the same set of devices, and integrate the ion separation membrane filtration process to efficiently remove suspended matter, oil, and hardness ions, avoid secondary pollution or sludge generation caused by large-scale addition of chemicals, provide high-quality pretreatment process and influent water quality conditions for the electrodialysis process, which is more environmentally friendly, optimizes the water quality of produced water and effectively reduces the influent treatment pressure of the electrodialysis process.

Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 shows a schematic flow chart of an electrodialysis process pretreatment test device of the present invention;

FIG2 shows a PID diagram of the device including control nodes and pipeline settings for the ultrafiltration organic membrane/ultrafiltration inorganic membrane process of the present invention;

FIG3 shows a PID diagram of the nanofiltration fouling ion separation membrane process including control nodes and pipeline settings.

In the figure: 1. Ultrafiltration boost pump; 2. Ultrafiltration raw water tank; 3. Air compressor; 4. Air storage tank; 5. Organic membrane circulation pump; 6. Ultrafiltration organic membrane; 7. Inorganic membrane circulation pump; 8. Ultrafiltration inorganic membrane; 9. Ultrafiltration water production tank; 10. Ultrafiltration backwash pump; 11. Nanofiltration boost pump; 12. Nanofiltration raw water tank; 13. Water supply pump; 14. Security filter; 15. High-pressure pump; 16. Ion separation membrane; 17. Nanofiltration water production tank; 18. Nanofiltration cleaning pump.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

An electrodialysis process pretreatment test device, as shown in FIG1, includes an ultrafiltration unit and a nanofiltration unit; wherein the ultrafiltration unit includes an ultrafiltration lift pump 1, an ultrafiltration raw water tank 2, an ultrafiltration module and an ultrafiltration water production tank 9; the ultrafiltration lift pump 1 is connected to the ultrafiltration raw water tank 2, and is used to transport the water to be treated to the ultrafiltration raw water tank 2; in addition, the ultrafiltration raw water tank 2 is connected to the ultrafiltration module, and the ultrafiltration module is used to ultrafilter the water to be treated, and transport the ultrafiltered water to the ultrafiltration water production tank 9; the ultrafiltration module is connected to the ultrafiltration water production tank 9, and the ultrafiltration water production tank 9 is connected to the nanofiltration unit and the drain;

The nanofiltration unit includes a nanofiltration lift pump 11, a nanofiltration module and a nanofiltration water production tank 17; wherein the nanofiltration lift pump 11 is connected to the nanofiltration module, and is used to receive the water to be treated and/or the ultrafiltered water delivered by the ultrafiltration water production tank 9, and to deliver the water to be treated and/or the ultrafiltered water to the nanofiltration module; the nanofiltration module is connected to the nanofiltration water production tank 17, and is used to nanofilter the water to be treated and/or the ultrafiltered water, and to deliver the nanofiltered water to the nanofiltration water production tank 17, and the nanofiltration water production tank 17 is also connected to the drain outlet.

Furthermore, the ultrafiltration module includes a first pipeline and a second pipeline arranged in parallel; wherein, an organic membrane circulation pump 5 and an ultrafiltration organic membrane 6 connected in sequence are arranged on the first pipeline; and the ultrafiltration organic membrane 6 is connected to the ultrafiltration water production tank 9 and the drain outlet, and the cleaning liquid and the like can be discharged from the drain outlet in the cleaning state. In addition, the ultrafiltration organic membrane 6 is also connected to the ultrafiltration raw water tank 2, and is used to return the concentrated water to the ultrafiltration raw water tank 2 in the working state.

The second pipeline is provided with an inorganic membrane circulation pump 7 and an ultrafiltration inorganic membrane 8 connected in sequence; wherein the ultrafiltration inorganic membrane 8 is connected to the ultrafiltration water production tank 9 and the drain outlet; the ultrafiltration inorganic membrane 8 is also connected to the ultrafiltration raw water tank 2 for returning the concentrated water to the ultrafiltration raw water tank 2.

It should be noted that the material of the ultrafiltration organic membrane 6 is preferably PC (polycarbonate), but is not limited to PC. PS (polystyrene), PVDF (polyvinylidene fluoride), PAN (polyacrylonitrile), PES (polyether sulfone) materials are also acceptable. The material of the ultrafiltration inorganic membrane 8 is preferably SiC (silicon carbide), but is not limited to SiC. Al2O3 (aluminum oxide), ZrO2 (zirconium dioxide) and TiO2 (titanium dioxide) materials are also acceptable. The ultrafiltration inorganic membrane 8 and the ultrafiltration organic membrane 6 are two membranes of different materials, which are operated in parallel, and their treatment effects can be verified separately.

Furthermore, the ultrafiltration water production tank 9 is also connected to an ultrafiltration backwash pump 10; the ultrafiltration backwash pump 10 is used to transport water to the ultrafiltration organic membrane 6 and the ultrafiltration inorganic membrane 8 for water washing. The electrodialysis process pretreatment test device also includes an air compressor 3 and an air storage tank 4, the air compressor 3 is connected to the air storage tank 4, and the air storage tank 4 is connected to the ultrafiltration inorganic membrane 8, for air washing the ultrafiltration inorganic membrane 8.

It should be noted that the ultrafiltration inorganic membrane 8 needs to be backwashed with air and water. The air compressor 3 and the air storage tank 4 are set to provide backwashing gas for online backwashing. The ultrafiltration backwashing pump 10 and the ultrafiltration water production tank 9 constitute an ultrafiltration cleaning tank structure. In the cleaning state, the ultrafiltration backwashing pump 10 transports the water or cleaning liquid in the ultrafiltration water production tank 9 to the ultrafiltration organic membrane 6 and the ultrafiltration inorganic membrane 8 for cleaning, and then discharges the water or cleaning liquid from the drain. Similarly, the air compressor 3 and the air storage tank 4 in Figure 1 can perform air washing on the ultrafiltration inorganic membrane 8, and the waste gas can be discharged through the drain.

It should be further explained that the ultrafiltration inorganic membrane 8 and the ultrafiltration organic membrane 6 are designed as two operating interfaces. The first operating interface is the ultrafiltration inorganic membrane 8 filtration operating mode, and the other operating interface is the ultrafiltration organic membrane 6 filtration operating mode. The two modes are switched on the PLC control panel.

Furthermore, the nanofiltration module includes a nanofiltration raw water tank 12, a water supply pump 13, a security filter 14, a high-pressure pump 15 and an ion separation membrane 16 connected in sequence, and the ion separation membrane 16 is also connected to the nanofiltration raw water tank 12 for concentrated water reflux. The nanofiltration raw water tank 12 is also connected to the nanofiltration booster pump 11; the ion separation membrane 16 is connected to the nanofiltration water production tank 17.

It should be noted that the material of the ion separation membrane 16 is preferably an aromatic and polyacid hydrogen composite nanofiltration membrane, but is not limited thereto, and cellulose acetate (CA), sulfonated polysulfone (SPS), sulfonated polyethersulfone (SPES) and polyvinyl alcohol (PVA) materials are also acceptable. The operation interface of the ion separation membrane 16 is a scaling ion separation membrane operation mode, and the operation is performed in the PLC control panel.

It should be further explained that the water washing and backwashing design of the ultrafiltration inorganic membrane 8 and the ultrafiltration organic membrane 6 share the backwashing pipeline and water tank.

Furthermore, the nanofiltration water production tank 17 is also connected to a nanofiltration cleaning pump 18 , and the nanofiltration cleaning pump 18 is connected to the ion separation membrane 16 for washing the ion separation membrane 16 with water.

It should be noted that both the ultrafiltration organic membrane 6 and the ion separation membrane 16 need to be backwashed with water, and both are backwashed online. The ion separation membrane 16 can be operated alone, with the pre-ultrafiltration inorganic membrane 8 and the ultrafiltration organic membrane 6, which can be operated in series to deeply treat the effluent of the two ultrafiltration membranes.

It should be further explained that the main operating modes of the device of the present invention are circulation mode, direct discharge mode, and backwash mode. In the circulation mode, the sewage to be treated enters the ultrafiltration raw water tank 2 through the ultrafiltration lifting pump 1, enters the ultrafiltration module through the circulation pump, and a part of the membrane water enters the ultrafiltration water tank 9 as product water, and the other part flows back to the ultrafiltration raw water tank 2 for circulation, and the concentrated water also flows back to the ultrafiltration raw water tank 2 for circulation treatment. In the direct discharge mode, the sewage to be treated enters the ultrafiltration raw water tank 2 through the ultrafiltration lifting pump 1, enters the ultrafiltration module through the circulation pump, and a part of the membrane water enters the water tank as product water, and a part is directly discharged. In the backwash mode, the mode of using the water tank/raw water tank as a cleaning water tank to clean the membrane assembly, respectively realizing chemical cleaning and clean water cleaning. The ultrafiltration inorganic membrane 8 and the ultrafiltration organic membrane 6 and the ion separation membrane 16 can all operate independently. Among them, the linkage between the ultrafiltration inorganic membrane 8 and the nanofiltration, and the linkage between the ultrafiltration organic membrane 6 and the nanofiltration also have a circulation mode and a direct discharge mode. In addition, the devices of the present invention are connected by pipelines, and the pipelines and valves are made of SS316L stainless steel, and the electromagnetic flowmeter is made of titanium alloy, which has good tolerance to sewage. The present invention also has an instrument automatic control setting: an online pH meter, a pressure sensor, a liquid level switch, an electromagnetic flowmeter, an on-site pressure gauge, an on-site flowmeter, a solenoid valve, and a manual valve. In addition, a linkage is set between the liquid level switch and the pump, and both high and low liquid levels have an alarm function. The device of the present invention is divided into two skids, the ultrafiltration inorganic membrane 8 and the ultrafiltration organic membrane 6 are a skid body, and the ion separation membrane 16 is a skid body. The skid bodies can be connected and fixed to form a module, all of which are explosion-proof designs and can be hoisted to the site to carry out test work. The skid frames of the two skid bodies can be fixed together, and the total height of the equipment is less than 2 meters, which meets the container transportation conditions and is suitable for the design requirements of the equipment in the industrial field verification environment.

The ultrafiltration inorganic membrane 8 and the ultrafiltration organic membrane 6 are two membranes made of different materials. They are operated in parallel, and their treatment effects can be verified separately. After selecting an operation mode, the raw water enters the ultrafiltration inorganic membrane 8 device/ultrafiltration organic membrane 6 device through the circulation pump, and part of the membrane water enters the ultrafiltration water production tank 9 as product water, and the intercepted liquid also flows back to the ultrafiltration raw water tank 2 for circulation treatment. The water in the ultrafiltration water production tank 9 can enter the nanofiltration raw water tank 12 through the nanofiltration lifting pump 11, and enter the security filter 14 and the ion separation membrane 16 successively under the action of the water supply pump 13. Part of the water produced by the ion separation membrane 16 enters the nanofiltration water production tank 17, and the intercepted liquid flows back to the nanofiltration raw water tank 12 for further concentration treatment.

An electrodialysis process pretreatment process is used for an electrodialysis process pretreatment test device, and the device includes working steps:

S1: ultrafiltration or nanofiltration of the treated water;

S2: Discharge the water after ultrafiltration treatment or perform nanofiltration treatment;

S3: Discharge the water after nanofiltration treatment.

Further, in S1, the water to be treated is subjected to ultrafiltration treatment, including:

Ultrafiltration of the water to be treated using an ultrafiltration organic membrane 6, and/or ultrafiltration of the water to be treated using an ultrafiltration inorganic membrane 8;

The ion separation membrane 16 is used to perform nanofiltration on the water to be treated and/or the water after the ultrafiltration treatment.

The parameters of the ultrafiltration organic membrane 6, the ultrafiltration inorganic membrane 8, the ion separation membrane 16 and the backwashing agent in the electrodialysis process pretreatment process are described below:

Main parameters of ultrafiltration organic membrane 6: rolled membrane; outlet pipe interface size 19mm; component diameter 61mm; component length 1016mm; guide layer flow channel height 2.28mm.

Main parameters of ultrafiltration inorganic membrane 8: membrane element outer diameter 40mm; membrane tube length 1200mm.

The main parameters of the ion separation membrane 16 are: membrane component diameter 61mm; membrane component length 965mm; inner diameter 21.1mm. Membrane products of different materials and brands can be replaced in the membrane shell.

The backwashing agents are: 0.5% NaOH solution; 0.5% NaOCl; 0.5% HCl solution; 0.1% NaOH solution.

As shown in Figures 2 and 3, "SV-digital" indicates a manual valve, such as SV-001, "KV-digital" indicates a solenoid valve, such as KV-001; "AT-digital" indicates a pH meter, such as AT-001; "AIR-digital" indicates analysis and local recording, such as AIR-001; "LS-digital" indicates a liquid level switch; "LSA-digital" indicates a liquid level switch alarm, A indicates an alarm; "I-digital" indicates local indication; "PIR-digital" indicates pressure local recording; "PT-digital" indicates a pressure sensor; "PG-digital" indicates a local pressure gauge; "LA-digital" indicates a liquid level alarm; "FRQ-digital" indicates a flow accumulation record; "FT" indicates a flow transmitter; "FG-digital" indicates a local flow meter; "AI-digital" indicates a local display analysis instrument; "AT-digital" indicates a remote analysis instrument; "NO" indicates normally open; "NC" indicates normally closed; and "FT-digital" indicates an electromagnetic flow meter.

The detailed operation of the electrodialysis process pretreatment process is as follows in conjunction with Figures 2 and 3:

1. Start the machine

The ultrafiltration organic membrane 6 and the ultrafiltration inorganic membrane 8 are set in parallel. Select one of the membranes for testing. Before the test, you need to confirm the status of the manual valves SV-001 to SV-016, and then click "Ultrafiltration Organic Membrane 6 Operation" or "Ultrafiltration Inorganic Membrane 8 Operation" on the touch screen, and the system will enter the automatic operation state.

There are two sources of water for the nanofiltration unit, one is the produced water of the ultrafiltration unit, and the other is an external water source. Before the test, the status of the manual valves from SV-017 to SV-030 must be confirmed. Then click "Scaling Ion Separation Membrane Operation" on the touch screen, and the system enters the automatic operation state. Under the control of the PLC program, the corresponding solenoid valves, lifting pumps, and circulating pumps are automatically opened. The system is in the continuous operation stage. After the circulating pump runs for 30 minutes (accumulated operating time, adjusted according to the operating conditions), it enters the backwash stage. The backwash time is about 15S, and it returns to the normal operation stage after the backwash is completed.

2. Key working conditions

(1) When the ultrafiltration organic membrane 6 and ultrafiltration inorganic membrane 8 systems are continuously inflowing water, the start and stop of the ultrafiltration booster pump 1 is controlled by the liquid level switch on the ultrafiltration raw water tank 2. When the test is in batch mode, when the water level in the ultrafiltration raw water tank 2 is filled to the high liquid level, the ultrafiltration booster pump 1 is manually turned off.

(2) When the ultrafiltration unit is first operated, the opening degree of the manual valves SV-005 and SV-006 needs to be adjusted so that the value of FG-001 on the flow meter is 50 L/h. The opening degree remains unchanged during subsequent operation and the flow meter value is observed to see if there is any change.

(3) When the ultrafiltration inorganic membrane 8 is backwashed, air backwashing is required. When the ultrafiltration inorganic membrane 8 is running, the air compressor 3 is in the on state. If the pressure in the air storage tank 4 is lower than 0.8MPa, the air compressor 3 starts to inflate and automatically shuts down when the pressure value is reached. After the backwash is completed once, the pressure drops, and the air compressor 3 automatically replenishes air to the air storage tank 4. The amount of air required for backwashing is small, and the opening degree of the outlet valve of the air storage tank 4 needs to be adjusted.

(4) Observe the pressure values on the membrane water and concentrate pipelines, and the FG-001 value. If the outlet water pressure decreases and the FG-001 value drops by 10-15%, it means that the membrane needs to be cleaned.

(5) The liquid level switch LS-003 generates a high liquid level alarm, and the system stops running. After the alarm, the manual valve SV-013 is opened to prevent overflow, and then the system is restarted.

(6) When the nanofiltration unit is continuously inflowing water, the start and stop of the nanofiltration lift pump 11 is controlled by the liquid level switch on the nanofiltration raw water tank 12. When the test is in batch mode, when the water volume in the system meets the flow rate of the circulating pump, the nanofiltration lift pump 11 is manually turned off.

(8) When the nanofiltration unit is first operated, the opening degree of the manual valves SV-022 and SV-023 needs to be adjusted so that the value of FG-002 on the flow meter is 50 L/h. The opening degree remains unchanged during subsequent operation and the flow meter value is observed to see if there is any change.

(9) Observe the pressure values on the ion separation membrane 16 product water and concentrate pipes, and the FG-002 value. If the outlet water pressure decreases and the FG-002 value decreases by 10-15%, it means that the membrane needs to be cleaned.

(10) Liquid level switch LS-007 high liquid level alarm, after the alarm opens the manual valve SV-026 to prevent overflow.

(11) When the wastewater to be treated comes from ultrafiltration water, pay attention to the liquid level of the ultrafiltration water tank 9 to prevent the liquid level from being too low and the pump from running idle.

3. Equipment stop

(1) Before the system stops running, it is recommended to clean the system with clean water to reduce the corrosion of the equipment and pipelines by the salt-containing wastewater remaining in the equipment;

(2) Open valves SV-013, SV-014, SV-026, and SV-028 to discharge the test wastewater out of the system, close the valves, inject fresh water into the ultrafiltration raw water tank 2, and click "ultrafiltration organic membrane operation" or "ultrafiltration inorganic membrane operation" and "scaling ion separation membrane operation" on the touch screen to enter the cleaning state. The fresh water runs in the system for 10 to 15 minutes;

(3) Click the "Ultrafiltration organic membrane system shut down" or "Ultrafiltration inorganic membrane system shut down" and "Scaling ion separation membrane shut down" buttons on the touch screen to stop the system;

(4) Open valves SV-014, SV-013, SV-026, and SV-028, drain the water in the tank, and close the valves.

(5) The manual valve on the equipment remains in its original state and the solenoid valve is in the closed state.

(6) When the equipment encounters an unexpected situation, press the emergency stop button on the electrical control cabinet or directly cut off the main power supply.

4. Chemical cleaning

Chemical cleaning cycle: When the equipment is intermittently operated and the interval is long, chemical cleaning is performed after each test. When the equipment is continuously operated, observe the value of the flow meter FT-001 on the water production pipeline. When the flow rate drops by 10-15%, the ultrafiltration organic membrane 6/ultrafiltration inorganic membrane 8 system needs to be chemically cleaned; observe the value of the flow meter FG-002 on the water production pipeline. When the flow rate drops by 10-15%, the nanofiltration membrane system needs to be chemically cleaned.

Chemical cleaning steps:

1) Ultrafiltration unit

(1) Chemical cleaning uses the ultrafiltration raw water tank 2, using system water or fresh water. First, add a certain amount of water to the ultrafiltration raw water tank 2 and prepare a 0.5% NaOH solution (the ultrafiltration inorganic membrane uses 0.5% NaOCl or 0.5% NaOH solution).

(2) When cleaning the ultrafiltration organic membrane 6, open the solenoid valves KV-001 and KV-019, start the organic membrane circulation pump 5, and the cleaning liquid circulates in the system for 30 minutes. During operation, use the ultrafiltration water tank 9 as the cleaning water tank, open the ultrafiltration backwash pump 10, and then open the valve of the ultrafiltration organic membrane 6 to clean the membrane, and then backwash it. The cleaning liquid returns to the ultrafiltration raw water tank 2 along the concentrated water reflux line, and is transported to the ultrafiltration unit through the circulation pump, and then returns to the ultrafiltration raw water tank 2 through the concentrated water reflux line. Then, close the organic membrane circulation pump 5, open the manual valve SV-014, and empty the liquid in the device.

(3) When cleaning the ultrafiltration inorganic membrane 8, open the solenoid valves KV-004 and KV-020, start the inorganic membrane circulation pump 7, and circulate the cleaning liquid in the system for 30 minutes. During operation, use the ultrafiltration water production tank 9 as the cleaning water tank, open the nanofiltration cleaning pump 18, open the valve of the ultrafiltration inorganic membrane 8, clean the membrane, and then backwash it. The cleaning liquid of the membrane returns to the nanofiltration raw water tank 12 along the concentrated water reflux line, and the cleaning liquid is transported to the ultrafiltration unit through the circulation pump, and then returns to the ultrafiltration raw water tank 2 through the concentrated water reflux line. Then, close the inorganic membrane circulation pump 7, open the manual valve SV-014, and drain the liquid in the system.

(4) Add fresh water into the ultrafiltration raw water tank 2, run the electrodialysis process pretreatment test device until the pH is neutral, check the water production, and if the difference between the fresh water production rate and the fresh water production rate obtained by the first test under the same conditions is within 10%, stop chemical cleaning. If it exceeds 10%, use acid solution for chemical cleaning again.

(5) Prepare 0.5% hydrochloric acid solution in the raw water tank and repeat the above steps for chemical cleaning until the fresh water production rate is within 10% of the value measured under the same conditions.

2) Nanofiltration unit

(1) Chemical cleaning uses a nanofiltration water production tank 17, using system water or fresh water, and a NaOH solution with a concentration of 0.1% is configured in the water production tank.

(2) Open the solenoid valves KV-010, KV-011 and KV-012, open the manual valves SV-021, SV-024 and SV-025, start the nanofiltration cleaning pump 18, and circulate the cleaning liquid in the system for 10 minutes. Then turn off the nanofiltration cleaning pump 18 and immerse the ion separation membrane 16 completely in the cleaning liquid. After 10 minutes, start the nanofiltration cleaning pump 18. After running for 10 minutes, turn off the nanofiltration cleaning pump 18, open the manual valve SV-026, and drain the liquid in the tank.

(4) After the alkaline solution cleaning is completed, fresh water is added to the nanofiltration raw water tank 12, and the "scaling ion separation membrane operation" on the touch screen is clicked to operate the system until the pH is neutral. The water production is checked. If the difference between the fresh water production rate and the water production value obtained by the first test under the same conditions is within 10%, the chemical cleaning is stopped. If it exceeds 10%, acid solution is required for chemical cleaning again.

(5) A 0.1% hydrochloric acid solution is placed in the nanofiltration water production tank 17, and the above nanofiltration unit cleaning steps are repeated for chemical cleaning until the fresh water production rate is within 10% of the value measured under the same conditions.

Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (12)

1. An electrodialysis process pretreatment test device, characterized in that it includes an ultrafiltration unit and a nanofiltration unit; The ultrafiltration unit comprises an ultrafiltration booster pump (1), an ultrafiltration raw water tank (2), an ultrafiltration module and an ultrafiltration water production tank (9); the ultrafiltration booster pump (1) is connected to the ultrafiltration raw water tank (2) and is used to transport the water to be treated to the ultrafiltration raw water tank (2); The ultrafiltration raw water tank (2) is connected to an ultrafiltration module, and the ultrafiltration module is used to perform ultrafiltration on the water to be treated and transport the ultrafiltered water to the ultrafiltration water production tank (9); The ultrafiltration module is connected to an ultrafiltration water production tank (9), and the ultrafiltration water production tank (9) is connected to a nanofiltration unit and a drain outlet; The nanofiltration unit comprises a nanofiltration lift pump (11), a nanofiltration module and a nanofiltration water production tank (17); The nanofiltration lift pump (11) is connected to the nanofiltration module, and is used to receive the water to be treated and/or the ultrafiltered water delivered by the ultrafiltration water production tank (9), and deliver the water to be treated and/or the ultrafiltered water to the nanofiltration module; The nanofiltration module is connected to the nanofiltration water production tank (17) and is used to perform nanofiltration on the treated water and/or the water after ultrafiltration, and to transport the water after nanofiltration to the nanofiltration water production tank (17). The nanofiltration water production tank (17) is also connected to the drain outlet. 2. An electrodialysis process pretreatment test device according to claim 1, characterized in that the ultrafiltration module comprises a first pipeline and a second pipeline arranged in parallel; The first pipeline is provided with an organic membrane circulation pump (5) and an ultrafiltration organic membrane (6) which are connected in sequence; The ultrafiltration organic membrane (6) is connected to the ultrafiltration water production tank (9) and the drain outlet; The ultrafiltration organic membrane (6) is also connected to the ultrafiltration raw water tank (2) to return concentrated water to the ultrafiltration raw water tank (2); The second pipeline is provided with an inorganic membrane circulation pump (7) and an ultrafiltration inorganic membrane (8) which are connected in sequence; The ultrafiltration inorganic membrane (8) is connected to the ultrafiltration water production tank (9) and the drain outlet; The ultrafiltration inorganic membrane (8) is also connected to the ultrafiltration raw water tank (2) and is used to return concentrated water to the ultrafiltration raw water tank (2). 3. An electrodialysis process pretreatment test device according to claim 2, characterized in that the ultrafiltration water production tank (9) is also connected to an ultrafiltration backwash pump (10); the ultrafiltration backwash pump (10) is used to transport water to the ultrafiltration organic membrane (6) and the ultrafiltration inorganic membrane (8) for water washing. 4. An electrodialysis process pretreatment test device according to claim 2, characterized in that it also includes an air compressor (3) and a gas storage tank (4), the air compressor (3) is connected to the gas storage tank (4), and the gas storage tank (4) is connected to the ultrafiltration inorganic membrane (8) for air washing the ultrafiltration inorganic membrane (8). 5. An electrodialysis process pretreatment test device according to claim 2, characterized in that the nanofiltration module comprises a nanofiltration raw water tank (12), a water supply pump (13), a security filter (14), a high-pressure pump (15) and an ion separation membrane (16) connected in sequence; The ion separation membrane (16) is also connected to the nanofiltration raw water tank (12) for concentrated water reflux. 6. An electrodialysis process pretreatment test device according to claim 5, characterized in that the nanofiltration raw water tank (12) is also connected to the nanofiltration booster pump (11); the ion separation membrane (16) is connected to the nanofiltration water production tank (17). 7. An electrodialysis process pretreatment test device according to claim 1, characterized in that the nanofiltration water production tank (17) is also connected to a nanofiltration cleaning pump (18), and the nanofiltration cleaning pump (18) is connected to the ion separation membrane (16) for washing the ion separation membrane (16). 8. An electrodialysis process pretreatment process, characterized in that it is used for an electrodialysis process pretreatment test device as described in claim 5 or 6. 9. The electrodialysis pretreatment process according to claim 8, characterized in that it comprises the following steps: Perform ultrafiltration or nanofiltration on the water to be treated; Discharge the water after ultrafiltration treatment or perform nanofiltration treatment; The water treated by nanofiltration is discharged. 10. The electrodialysis pretreatment process according to claim 9, characterized in that the water to be treated is subjected to ultrafiltration treatment, comprising: Using an ultrafiltration organic membrane (6) to ultrafilter the water to be treated, and/or using an ultrafiltration inorganic membrane (8) to ultrafilter the water to be treated; The water to be treated and/or the water after ultrafiltration treatment is subjected to nanofiltration using an ion separation membrane (16). 11. The electrodialysis pretreatment process according to claim 8, characterized in that it comprises an ultrafiltration unit cleaning step: First, water is added to the ultrafiltration raw water tank (2) to prepare a cleaning solution, wherein the cleaning solution is a NaOH solution with a concentration of 0.5%; Cleaning the ultrafiltration organic membrane (6), after the cleaning liquid circulates in the pretreatment test device for 30 minutes, the liquid in the device is emptied; Cleaning the ultrafiltration inorganic membrane (8), after the cleaning liquid circulates in the pretreatment test device for 30 minutes, the liquid in the device is emptied; Add fresh water into the ultrafiltration raw water tank (2), run the pretreatment test device until the pH is neutral, check the water production, and if the difference between the fresh water production rate and the fresh water production rate obtained by the first test under the same conditions is within 10%, stop chemical cleaning. If it exceeds 10%, use acid solution to perform chemical cleaning again; A 0.5% hydrochloric acid solution is placed in the ultrafiltration raw water tank (2), and the above steps are repeated for chemical cleaning until the fresh water production rate is within 10% of the value measured under the same conditions. 12. The electrodialysis pretreatment process according to claim 8, characterized in that it comprises a nanofiltration unit cleaning step: A NaOH solution with a concentration of 0.1% is prepared in a nanofiltration water production tank (17); The nanofiltration cleaning pump (18) is started, and the cleaning liquid is circulated in the system for 10 minutes. The nanofiltration cleaning pump (18) is closed, and the ion separation membrane (16) is completely immersed in the cleaning liquid. After 10 minutes, the nanofiltration cleaning pump (18) is started, and after running for 10 minutes, the nanofiltration cleaning pump (18) is closed, and then the liquid in the nanofiltration water production tank (17) is emptied; Add fresh water into the nanofiltration raw water tank (12), start the device operation mode, until the pH of the produced water is close to neutral, check the water production, and if the difference between the fresh water production rate and the fresh water production rate obtained by the first test under the same conditions is within 10%, stop chemical cleaning. If it exceeds 10%, use acid solution to perform chemical cleaning again; A 0.1% hydrochloric acid solution is placed in the nanofiltration water production tank (17) for chemical cleaning until the fresh water production rate is within a 10% range of the value measured under the same conditions.