17 Feb 2025
How to use the new RO reverse osmosis membrane correctly?
Technical points for using new RO reverse osmosis membrane:
1. First, rinse the quartz sand and coconut shell activated carbon. The newly installed quartz sand and coconut shell activated carbon should be rinsed for a longer time.
2. Check whether there is residual chlorine. If the residual chlorine exceeds the standard, solve the residual chlorine problem and then proceed to the next step of RO reverse osmosis membrane.
3. After the new membrane is installed, rinse it with water and soak it for 1 to 2 hours. Because it is a dry membrane, the soaked membrane is relatively moist to prevent the membrane from being damaged by too high pressure.
4. Then start the high-pressure pump. The pressure should be increased slowly from 2 kg to 8 to 10 kg, which will have a better desalination effect on the new membrane.
5. The residual chlorine is controlled below 0.003.
6. Open the concentrated water valve before starting the high-pressure pump. After the high-pressure pump is turned on, slowly adjust the concentrated water valve to control the recovery rate of a single membrane to about 15%.
7. The water produced in the first half an hour must be discharged because there is a protective liquid in the membrane to avoid affecting the taste of the water.
8. Check the pH value of the incoming water, which should be above 6.5.
How to judge whether the reverse osmosis membrane needs to be cleaned?
Under normal circumstances, reverse osmosis membrane elements can be used for about 2 to 3 years. If you want to extend the service life, you can clean the reverse osmosis membrane elements, which are usually divided into two ways: physical flushing and chemical flushing. When physical flushing can no longer restore the performance of the reverse osmosis membrane, chemical cleaning should be performed. Under normal circumstances, reverse osmosis membrane elements can be used for about 2 to 3 years. If you want to extend the service life, you can clean the reverse osmosis membrane elements, which are usually divided into two ways: physical flushing and chemical flushing. When physical flushing can no longer restore the performance of the reverse osmosis membrane, chemical cleaning should be performed.
(2) The standardized salt permeability increased by more than 10%.
(3) In order to maintain normal fresh water flow, the pressure difference between feed water and concentrate increased by more than 10% after temperature calibration.
(4) There are serious pollutants and scaling in the internal device.
(5) Before the RO device is shut down for a long time.
(6) Routine maintenance of the RO device.
After the reverse osmosis equipment has been operating normally for a period of time, the reverse osmosis membrane element will be contaminated by suspended matter or insoluble salts that may exist in the feed water, and the following symptoms will occur:
1. The weight of the reverse osmosis equipment membrane element increases;
2. The RO membrane removal rate increases or decreases significantly;
3. Under standard pressure, the water output of the reverse osmosis equipment decreases significantly;
4. In order to achieve the standard water output, the operating pressure needs to be improved;
5. The pressure drop between the inlet water and the concentrated water of the reverse osmosis equipment increases;
6. Take the membrane element out of the pressure vessel and pour water on the inlet side of the erected membrane element. If the water cannot flow through the membrane element and only overflows from the end face, it indicates that the inlet flow channel is blocked.
Whether the reverse osmosis membrane element needs to be replaced depends on the actual situation.
1. First, rinse the quartz sand and coconut shell activated carbon. The newly installed quartz sand and coconut shell activated carbon should be rinsed for a longer time.
2. Check whether there is residual chlorine. If the residual chlorine exceeds the standard, solve the residual chlorine problem and then proceed to the next step of RO reverse osmosis membrane.
3. After the new membrane is installed, rinse it with water and soak it for 1 to 2 hours. Because it is a dry membrane, the soaked membrane is relatively moist to prevent the membrane from being damaged by too high pressure.
4. Then start the high-pressure pump. The pressure should be increased slowly from 2 kg to 8 to 10 kg, which will have a better desalination effect on the new membrane.
5. The residual chlorine is controlled below 0.003.
6. Open the concentrated water valve before starting the high-pressure pump. After the high-pressure pump is turned on, slowly adjust the concentrated water valve to control the recovery rate of a single membrane to about 15%.
7. The water produced in the first half an hour must be discharged because there is a protective liquid in the membrane to avoid affecting the taste of the water.
8. Check the pH value of the incoming water, which should be above 6.5.
How to judge whether the reverse osmosis membrane needs to be cleaned?
Under normal circumstances, reverse osmosis membrane elements can be used for about 2 to 3 years. If you want to extend the service life, you can clean the reverse osmosis membrane elements, which are usually divided into two ways: physical flushing and chemical flushing. When physical flushing can no longer restore the performance of the reverse osmosis membrane, chemical cleaning should be performed. Under normal circumstances, reverse osmosis membrane elements can be used for about 2 to 3 years. If you want to extend the service life, you can clean the reverse osmosis membrane elements, which are usually divided into two ways: physical flushing and chemical flushing. When physical flushing can no longer restore the performance of the reverse osmosis membrane, chemical cleaning should be performed.
Reverse osmosis membrane cleaning
According to experience, if the reverse osmosis device is cleaned every three months or longer, if it is cleaned once every 1-3 months, it is necessary to improve the operating conditions and enhance the pretreatment effect.
1. Judge the cleaning situation:
(1) The standardized fresh water production decreased by more than 10%.(2) The standardized salt permeability increased by more than 10%.
(3) In order to maintain normal fresh water flow, the pressure difference between feed water and concentrate increased by more than 10% after temperature calibration.
(4) There are serious pollutants and scaling in the internal device.
(5) Before the RO device is shut down for a long time.
(6) Routine maintenance of the RO device.
Before deciding whether to clean the reverse osmosis system, you should also consider the following other possible reasons for the above phenomenon:
☆ Drop in operating pressure (failure of the pressure control device and abnormality of the high-pressure pump);
☆ Drop in inlet water temperature (heater failure, or seasonal changes causing water temperature drop);
☆ Increase in inlet water salt content;
☆ Abnormal pretreatment;
☆ Concentrated water seeping into fresh water due to membrane damage, misalignment of the central tube of the series membrane element, and poor sealing of the O-ring of the pressure vessel.
☆ Drop in operating pressure (failure of the pressure control device and abnormality of the high-pressure pump);
☆ Drop in inlet water temperature (heater failure, or seasonal changes causing water temperature drop);
☆ Increase in inlet water salt content;
☆ Abnormal pretreatment;
☆ Concentrated water seeping into fresh water due to membrane damage, misalignment of the central tube of the series membrane element, and poor sealing of the O-ring of the pressure vessel.
2. Pollutants
Common pollutants in reverse osmosis membrane elements include CaCO3, CaSO4, BaSO4, SrSO4, metal oxides, silicon deposits, organic matter and biological slime. When the antiscalant dosing system or acid addition system fails, CaCO3 may be deposited in the membrane element, and chemical cleaning methods should be adopted for circulation cleaning or overnight soaking.
3. Formula
Different pollutants cause different degrees of damage to the membrane, and different pollutants should use different cleaning solutions.
3. Formula
Different pollutants cause different degrees of damage to the membrane, and different pollutants should use different cleaning solutions.
4. Cleaning equipment
(1) Reverse osmosis cleaning system
Generally consists of a cleaning pump, a reagent preparation box, a 5-20um safety filter, a heater, related pipeline valves and control instruments.
(2) Operation
Generally consists of a cleaning pump, a reagent preparation box, a 5-20um safety filter, a heater, related pipeline valves and control instruments.
(2) Operation
Cleaning methods include static immersion and circulation cleaning. Static immersion uses cleaning liquid to soak the membrane for approximately 1-15 hours depending on the degree of contamination.
The general steps of circulation cleaning are:
1. Use a pump to send fresh water from the reagent preparation box into the pressure vessel and drain it for a few minutes.
2. Prepare the cleaning solution with fresh water in the reagent preparation box.
3. Use the cleaning solution to circulate and clean the pressure vessel for 1 hour or until the predetermined time. The cleaning flow rate can be determined according to the table below. When the pollution is serious, the cleaning flow rate can be increased to 150% of the resin in the table. At this time, the cleaning pressure drop is large, and it is generally controlled not to exceed (0.10-0.14MPa)/root membrane element or 0.4MPa/root membrane assembly. At the beginning of the drug cleaning, 50% of the flow value in the table can be used to inject the heated cleaning solution into the pressure vessel, and the pressure can be controlled to overcome the pressure drop between the inlet and outlet water without fresh water flowing out. In order to avoid dilution of the cleaning solution, the concentrated water discharge valve can be opened to drain the system water before cleaning. The reverse osmosis system can be cleaned in sections. The cleaning direction is the same as the running direction. Reverse cleaning is not allowed, otherwise it may cause the membrane roll to bulge and damage the membrane element.
4. After the cycle cleaning is completed, clean the reagent preparation box with fresh water.
5. Rinse the above pressure vessels with fresh water.
6. After the flushing is completed, run the reverse osmosis system with the fresh water discharge valve open until the fresh water is clean and free of foam or cleaning fluid, which usually takes 15-30 minutes.
The general steps of circulation cleaning are:
1. Use a pump to send fresh water from the reagent preparation box into the pressure vessel and drain it for a few minutes.
2. Prepare the cleaning solution with fresh water in the reagent preparation box.
3. Use the cleaning solution to circulate and clean the pressure vessel for 1 hour or until the predetermined time. The cleaning flow rate can be determined according to the table below. When the pollution is serious, the cleaning flow rate can be increased to 150% of the resin in the table. At this time, the cleaning pressure drop is large, and it is generally controlled not to exceed (0.10-0.14MPa)/root membrane element or 0.4MPa/root membrane assembly. At the beginning of the drug cleaning, 50% of the flow value in the table can be used to inject the heated cleaning solution into the pressure vessel, and the pressure can be controlled to overcome the pressure drop between the inlet and outlet water without fresh water flowing out. In order to avoid dilution of the cleaning solution, the concentrated water discharge valve can be opened to drain the system water before cleaning. The reverse osmosis system can be cleaned in sections. The cleaning direction is the same as the running direction. Reverse cleaning is not allowed, otherwise it may cause the membrane roll to bulge and damage the membrane element.
4. After the cycle cleaning is completed, clean the reagent preparation box with fresh water.
5. Rinse the above pressure vessels with fresh water.
6. After the flushing is completed, run the reverse osmosis system with the fresh water discharge valve open until the fresh water is clean and free of foam or cleaning fluid, which usually takes 15-30 minutes.
Reverse osmosis membrane replacement
After the reverse osmosis equipment has been operating normally for a period of time, the reverse osmosis membrane element will be contaminated by suspended matter or insoluble salts that may exist in the feed water, and the following symptoms will occur:
1. The weight of the reverse osmosis equipment membrane element increases;
2. The RO membrane removal rate increases or decreases significantly;
3. Under standard pressure, the water output of the reverse osmosis equipment decreases significantly;
4. In order to achieve the standard water output, the operating pressure needs to be improved;
5. The pressure drop between the inlet water and the concentrated water of the reverse osmosis equipment increases;
6. Take the membrane element out of the pressure vessel and pour water on the inlet side of the erected membrane element. If the water cannot flow through the membrane element and only overflows from the end face, it indicates that the inlet flow channel is blocked.
Whether the reverse osmosis membrane element needs to be replaced depends on the actual situation.