With the widespread application of water purification equipment in the water treatment industry, reverse osmosis membranes have received increasing attention.
Reverse osmosis membranes have high precision and can thoroughly filter out pollutants in drinking water. They are also more expensive than ordinary water filter cartridges. Proper maintenance during use can help extend the service life of the reverse osmosis membrane and reduce costs.
New reverse osmosis membrane elements are usually immersed in a 1% NaHSO3 and 18% glycerol aqueous solution and stored in a sealed plastic bag. If the plastic bag remains intact, storage for about a year will not affect the membrane's lifespan or performance. Once the plastic bag is opened, it should be used as soon as possible to prevent the NaHSO3 from oxidizing in the air and adversely affecting the element. Therefore, the membrane should be opened just before use.
After the equipment is tested, we have two methods to protect the reverse osmosis membrane. After the equipment test runs for 15-24 hours, use a 2% formaldehyde solution for maintenance; or after running for 2-6 hours, use a 1% NaHSO3 aqueous solution to maintain the reverse osmosis membrane (air in the equipment pipeline should be drained, ensuring the equipment is leak-proof, and all inlet and outlet valves are closed).
Both methods are effective, but the first method is more expensive and is used when the equipment is idle for a long time, while the second method is used when the idle time is shorter.
The general steps for cleaning reverse osmosis membrane elements are:
1. Use a pump to pump clean, chlorine-free reverse osmosis product water from the cleaning tank (or corresponding water source) into the pressure vessel and drain for a few minutes.
2. Prepare the cleaning solution in the cleaning tank using clean product water.
3. Circulate the cleaning solution in the pressure vessel for 1 hour or a preset time.
4. After cleaning is complete, drain the cleaning tank and rinse it. Then fill the cleaning tank with clean product water for the next rinsing step.
5. Use a pump to pump clean, chlorine-free product water from the cleaning tank (or corresponding water source) into the pressure vessel and drain for a few minutes.
6. After rinsing the reverse osmosis system, run the reverse osmosis system with the product water drain valve open until the product water is clean, free of foam, or free of cleaning agent (usually 15-30 minutes).
Of course, the maintenance of the reverse osmosis membrane should also include adding pre-treatment.
For reverse osmosis membrane elements, in most cases, the water source cannot directly enter the reverse osmosis membrane element because the impurities it contains will contaminate the membrane element, affecting the stable operation of the system and the service life of the membrane element.
Therefore, in order to ensure the stable operation of the reverse osmosis system, pretreatment of the feed water is essential. For example, multi-media filters, activated carbon filters, scale inhibitors, and security filters, etc., can eliminate suspended solids in the water, reduce water turbidity, and sterilize to prevent the growth of microorganisms, which can effectively extend the service life of the reverse osmosis membrane.
If the pretreatment system fails to function, more pollutants enter the reverse osmosis system, which will greatly reduce the life of the reverse osmosis membrane. This not only increases the water purification cost but may also affect the quality of the effluent.
