Membrane Installation Instructions

■ Installation Preparation of Membrane Elements
1. Storage of membrane elements: The storage and transportation of membrane elements before installation and use should be kept dry and ventilated, avoid direct sunlight, avoid contact with oxidizing gases, and the storage temperature should be 5-45℃.
2. Tool preparation: Prepare disassembly tools, glycerin, rubber safety boots or waterproof iron-headed boots, protective glasses, gloves, clean cloth, etc.
3. System preparation: Check the upstream water inlet pipeline to remove all dust, grease, metal debris, etc. If necessary, the water inlet pipeline and reverse osmosis pressure vessel should be chemically cleaned to ensure that all foreign matter is effectively removed. Before installing the membrane element, the membrane pressure vessel should be rinsed with qualified water produced by the pretreatment system for 30 minutes, and the pipeline should be checked for leaks. Check whether the main indicators of the pretreatment water (such as SDI, turbidity, residual chlorine, temperature, pH, ORP) meet the requirements of reverse osmosis/nanofiltration water quality.

4.Remove the end plate and thrust ring of the pressure vessel. The end plate structure of pressure vessels of different brands is different. When disassembling, refer to the corresponding product schematic diagram.
5. Preparation for cleaning and lubrication of membrane shell: Rinse the opened pressure vessel with clean water to remove dust and sediment. Wet the inner wall of the pressure vessel with 50% glycerol aqueous solution (e.g., make a mop that can fill the pressure vessel) to keep the inner wall of the pressure vessel clean and lubricated to facilitate the installation of membrane elements.
6. After all the above preparations are completed, open the plastic packaging bag of the membrane element before putting the system into operation, install the membrane element, and try to shorten the time the membrane element is exposed to the air.

■ Disassembly of Membrane Elements
1. Remove the external pipes (water inlet, concentrated water, and produced water pipes) at both ends of the pressure vessel, remove the end plate sealing assemblies at both ends of the pressure vessel, number all the removed parts and put them in order;
2. Use a PVC pipe or other disassembly tools to push the membrane elements out from the water inlet end of the pressure vessel to the concentrated water end. Only one membrane element is allowed to be pushed out each time. When the element is pushed out of the pressure vessel, it should be supported in time and the membrane element should be placed flat to prevent the center tube connector from being damaged by force. The membrane element can be rotated appropriately to separate the element from the center tube connector.
3. After the disassembled membrane element is cleaned, it should be stored in an environment of 5-35℃ and immersed in 1% sodium bisulfite solution to prevent the membrane from being oxidized. (1% sodium bisulfite solution must be prepared with RO water and food-grade sodium bisulfite).

■ Installation of Membrane Elements
1. Carefully take out the membrane element from the packaging box and check whether the position and direction of the "Y" ring (water inlet sealing ring) on ​​the element are correct (the opening direction of the water inlet sealing ring must face the water inlet direction, that is, the side of the membrane element with the "Y" ring faces the water inlet direction). 
2. The membrane element must be installed from the water inlet end of the pressure vessel, and the end of the first membrane element without the "Y" ring is pushed into the pressure vessel in parallel until the membrane element is exposed about 20cm outside the pressure vessel. 
3. Use glycerin (avoid using surfactants that damage the membrane) to apply a small amount of "Y" ring and the "o" ring on the connector, and insert the connector into the center tube of the first membrane element. 
4. Carefully take out the second membrane element from the packaging box. Also check whether the position and direction of the water inlet sealing ring on the element are correct. Carefully hold the element and insert the internal joint on the first element into the central water production pipe of the element. At this time, the connecting internal joint cannot be subjected to external force. Push the second membrane element into the pressure vessel until it is exposed about 20cm outside the pressure vessel. Apply a small amount of glycerin to the "Y" ring and the "o" ring on the connector, and insert the connector into the central tube of the second membrane element. 
5. Repeat steps 3 and 4 until all elements are installed in the pressure vessel, transfer to the concentrated water end, and install the element internal joint on the central water production pipe of the first element. 
6. Install the thrust ring at the concentrated water end of the pressure vessel. When positioning the thrust ring, refer to the schematic diagram of the pressure vessel manufacturer (do not forget to install the thrust ring. Failure to install the thrust ring at the concentrated water end of the pressure vessel will seriously damage the membrane element).
7. Install the end plate of the concentrate end of the pressure vessel. Carefully check the "O" ring on the element adapter and insert the element adapter into the concentrate end plate. In order to connect with the external pipeline, carefully position the concentrate end plate of the pressure vessel, align the element internal joint and push the concentrate end plate assembly into the pressure vessel in parallel, then rotate and adjust the concentrate end plate assembly to align it with the external connecting pipe, and then install the end plate clamp ring according to the schematic diagram of the pressure vessel manufacturer. 
8. Push the membrane element from the inlet side to the concentrate side until the first installed membrane element is firmly in contact with the concentrate end plate. 
9. Install the inlet end plate similar to step 7. Before installing the inlet end plate, it is recommended to use an adjustment plate to adjust the gap between the membrane element and the end plate (installing the adjustment plate can prevent the axial movement of the element and the impact between the elements when the system is started and stopped). 
10. Repeat the above steps to install the membrane element in each pressure vessel and connect all external inlet, concentrate and product water pipelines.

Start and Stop of Membrane Element System

■ Matters to Be Confirmed Before The First Operation
1. It is recommended to prepare the system for the first operation immediately after the membrane element is installed.
2. All pipelines and equipment should comply with the design pressure regulations and the pH range specified in the design.
3. Before connecting the pressure vessel, both the water inlet and high-pressure pipelines have been cleaned and flushed.
4. The multi-media filter (if any) has been backwashed and cleaned, and the effluent is qualified.
5. Confirm that the security filter in front of the high-pressure pump is installed with a clean new security filter element, and confirm that the filter element of the security filter is correctly installed.
6. Confirm that the pretreatment device is in a normal and effective operating state, and ensure that the following indicators of the membrane system inlet water are stable or qualified: stable water flow, pollution index (SDI), turbidity (NTU), residual chlorine and other oxidants, reducing agent concentration (if used to remove residual chlorine), pH value, conductivity, temperature, bacterial count, etc. And do a good job in pretreatment effluent water quality testing, and do regular testing and registration. If it is found that it exceeds the normal value, the operation of the pretreatment must be readjusted.
7. Confirm that the device to prevent back pressure is installed, and the water production pressure will not exceed the inlet or concentrate pressure by 0.03MPa at any time;
8. The location of the chemical dosing point is correct, appropriate mixing measures are taken in the dosing water inlet pipeline, and appropriate check valves and anti-siphon valves are installed on the dosing pipeline.
9. The reagents and their concentrations in the dosing box are correct.
10. When the dosing metering pump is shut down, the reverse osmosis and nanofiltration devices can be shut down.
11. When the reverse osmosis device and nanofiltration are shut down, the dosing metering pump can be shut down.
12. If oxidants such as chlorine are used, measures should be taken to ensure that the oxidants in the membrane system inlet water are completely removed.
13. According to the plan, measuring instruments that can effectively operate and monitor the pretreatment and reverse osmosis and nanofiltration systems are equipped.
14. The instruments listed in the plan are installed and can work normally, and the instruments are confirmed to be calibrated.
15. The pressure safety relief valve is installed and set correctly.
16. Each component can be sampled separately for produced water. The total system inlet water, each section’s inlet water, produced water, concentrated water and total produced water can be sampled.
17. The pressure vessel is correctly connected to the operation and cleaning pipelines.
18. The water pump is ready for operation, the coupling is well aligned, fully lubricated and can rotate easily and freely.
19. Tighten all joints and open the produced water outlet valve.
20. The produced water should be discharged directly to the ground (in a two-stage system, measures should be taken to prevent the produced water during the flushing of the first stage from entering the second stage of reverse osmosis. When the dry membrane element is installed in the first stage, it usually takes 6 to 8 hours).
21. Open the concentrated water control valve. Before starting the high-pressure pump, adjust the high-pressure pump outlet valve or bypass regulating valve to control the membrane system water flow rate to be less than 50% of the operating water flow.
After confirming the above matters, the system can be started under the condition that the membrane element has been correctly installed.

■ Initial Start-up of The System
1. Fill the membrane elements and pressure vessels with low-pressure (flushing pressure 0.2-0.4MPa) low-flow water, and flush at 1/3 of the membrane element water flow: the flushing flow of each 4-inch pressure vessel is 0.6-3.0m3/h, and the flushing flow of each 8-inch pressure vessel is 2.4-12.0m3/h. All produced water and concentrated water during the flushing process should be discharged.
2. During the water flushing operation, carefully check all valves and pipes for leaks, and tighten or repair them.
3. For systems with wet membranes installed, flush for at least 30 minutes before closing the membrane water inlet control valve. For systems with dry membranes installed, low-pressure flushing should be continued for more than 6 hours, or flush for 1-2 hours and soak overnight before flushing for about 1 hour.
4. Confirm that the water production valve and the concentrated water control valve are in the "open" position again, and check the switch status of other valves;
5. Before starting the high-pressure pump, it is necessary to confirm that the pump outlet water inlet control valve is in a state close to full closure to prevent the impact of water flow and water pressure on the membrane element;
6. After the high-pressure pump is started, the high-pressure pump outlet water inlet control valve should be slowly opened to increase the concentrated water flow rate to the design value evenly. The pressure increase rate should be lower than 0.07MPa/s (10psi/s).
7. While slowly opening the high-pressure pump outlet water inlet control valve, slowly close the concentrated water control valve to maintain the concentrated water discharge flow specified in the system design. At the same time, observe the system water production flow until the water production flow reaches the system design value, check the system operating pressure, and ensure that it does not exceed the design upper limit.
8. Check whether the dosage of all chemical agents is consistent with the design value, such as acid, scale inhibitor and sodium bisulfite, and monitor the pH value of the inlet water.
9. Check the Langelier Saturation Index (LSI) or the Steve-David Stability Index (S&DSI) of the concentrate, which are obtained by measuring the pH value, conductivity, calcium hardness and alkalinity of the concentrate and calculating them.
10. Detect the conductivity of the produced water of each pressure vessel, analyze whether there are corresponding pressure vessels that do not meet the expected performance, and determine whether there are leaks or other faults in the membrane elements and the "O" rings of the pressure vessels.

11.Confirm whether the safety devices of the machinery and instruments are operating properly.
12. Let the system run continuously for 1 hour. Once the produced water is qualified, open the qualified produced water delivery valve first and then close the produced water discharge valve to supply water to the subsequent equipment.
13. Record the relevant operating parameters.
14. The above system parameter adjustments are generally carried out in manual operation mode, and the system is converted to automatic operation mode after the system is stable.
15. After 24-48 hours of continuous operation, check all recorded system performance data, including: SDI, inlet water pressure, pressure difference, pH, temperature, flow rate, recovery rate and conductivity. At the same time, the influent, concentrate and total system product water are sampled and analyzed for their ion composition. The operating parameters at this time serve as the benchmark for system performance.

■ Daily Startup and Shutdown of Reverse Osmosis System
After the membrane system is put into operation, it is often started and stopped due to various objective reasons. Each start and stop may cause a sudden change in system pressure and flow, which will affect the membrane elements. Therefore, the start and stop times of the system equipment should be reduced as much as possible, and the normal start and stop process should be as smooth as possible. The startup method should be the same as the first startup steps in principle. The shutdown steps are as follows:
1. Slowly close the high-pressure pump outlet valve, stop the high-pressure pump, and open the water production discharge valve.
2. Flushing: The flushing time is about 10-30 minutes.
3. Stop flushing: Turn off the flushing water pump and close all valves.

■ Management During The Shutdown of The Reverse Osmosis System
1. Management during daily shutdown (0-5 days)
The management during daily shutdown (0-5 days) is carried out in accordance with the normal shutdown procedure. The key is to perform low-pressure flushing during shutdown, and repeat the flushing every 24 hours (to meet the reverse osmosis water inlet requirements).
2. Management during system shutdown (6-30 days)
The shutdown of the membrane system is carried out in accordance with the normal shutdown procedures. After shutdown, the pressure vessel should be filled with reverse osmosis water, and all water inlet, concentrated water valves and water production valves should be closed to prevent the membrane elements from drying and the growth of microorganisms. Repeat the flushing every 7 days (to meet the reverse osmosis water inlet requirements).
For surface water or water sources with high microbial contamination, use reverse osmosis water to prepare 1% sodium bisulfite solution to flush the reverse osmosis system. If the membrane elements are soaked in this solution at the same time, the effect will be better and the repeated flushing cycle will be extended accordingly.
Low temperature is conducive to the preservation of membrane elements. During system shutdown, the temperature should be kept between 5 and 35°C.
3. Management during long-term system shutdown (more than 30 days)
The shutdown of the membrane system is carried out according to the normal shutdown procedures, and the system is flushed with reverse osmosis water at low pressure. It is best to perform a chemical cleaning and sterilization treatment. After cleaning, the system is flushed with reverse osmosis water at low pressure until the conductivity of the concentrated water is consistent with the conductivity of the inlet water. Use reverse osmosis water to prepare 1% sodium bisulfite protection liquid to flush the membrane elements, remove the air in the pressure vessel, close all the inlet, concentrated water, and water valves, and keep the membrane elements moist.
Check the pH value of the protection liquid every week. When the pH is less than 3, the protection liquid should be replaced. Low temperature is conducive to the preservation of membrane elements. During system shutdown, the temperature should be kept between 5 and 35°C.