01 Membrane element storage method
Store the components in a cool and dry warehouse, or store them after packing. The minimum temperature should be higher than 5℃, and the best temperature should be kept at 10-20℃.
02 How to save the membrane system
1. Short-term storage
No flushing is required within 2 hours of shutdown
After shutdown for more than 2 hours, perform RO product water flushing for 20 minutes
2. Medium-term preservation
If the machine is shut down for 3 days or more, within 30 days, follow the steps below to save:
(1) In-line cleaning (CIP) RO membrane element;
(2) Rinse with RO product water for more than 30 minutes;
(3) When the flushing is over, keep the membrane in the flushing water (RO product water), close the valve and keep the solution in the RO section;
(4) Perform steps 2 and 3 once a week.
(5) In this method, it is necessary to ensure that the flushing water source is always clean, and to prevent the growth of microorganisms in the pipeline and water tank, so as to avoid secondary pollution to the membrane element.
3. Long-term storage
After shutdown for more than 30 days, use bisulfite to preserve the RO membrane, and operate according to the following steps:
(1) In-line cleaning (CIP) RO membrane element;
(2) Rinse with RO product water for more than 30 minutes;
(3) Use the 1.0% concentration of sodium bisulfite solution prepared with RO product water to flush the RO section;
(4) When the RO section is filled with the solution (requires full filling), close the valve and keep the solution in the RO section;
(5) When the temperature is lower than 27℃, repeat steps 1, 2, and 3 with fresh cleaning solution every 30 days; when the temperature is higher than 27℃, repeat steps 1, 2, and 3 with fresh solution every 15 days;
(6) The pH value of the solution should be controlled between 3.5-9.5, and should be tested regularly. If the pH is not within the above range, the protective fluid should be replaced, as prolonged exposure to acidic or alkaline environments can damage the membrane.
Regularly monitor the concentration of acid sulfite. If the concentration of the solution is lower than 0.1%, a new solution should be used, and the temperature should be kept below 25 ℃;
(7) When the ambient temperature may be lower than 5℃, the system must be filled with antifreeze, and the pipeline must be protected against freezing cracks.
Usually 30% glycerol or 20% ethylene glycol (freezing point is about -10℃) can be used as antifreeze. The operation steps are equivalent to the above method of long-term preservation of the membrane. First, the membrane is chemically cleaned and rinsed with pure water, and then replaced with antifreeze and sealed;
(8) When the RO system is ready to be restarted, open the water outlet valve and flush the system with low-pressure clean water until it is rinsed clean and the produced water is discharged. Before resuming the RO system, the permeate water needs to be checked for disinfectant residues.
