Common pollutants in reverse osmosis membrane and their removal methods

This article introduces the common pollution and cleaning methods that affect the performance of composite membranes, which are suitable for reverse osmosis membrane elements with 4 inch, 6 inch, 8 inch and 8.5 inch diameters.

Note 1: Under no circumstances should the water with free chlorine come into contact with the composite membrane element. If such contact occurs, the performance of the membrane element will be reduced, and its performance can no longer be restored. After the pipeline or equipment is sterilized It should be ensured that there is no free chlorine in the feed water sent to the reverse osmosis membrane element. It should be confirmed by laboratory tests. The acid solution should be used to neutralize the residual chlorine and ensure sufficient contact time to ensure complete reaction.

Note 2: During the warranty period of the reverse osmosis membrane element, it is recommended that each osmosis membrane cleaning should be carried out after consultation with the company. At least the first time, the company’s field service personnel should be on site.

Note 3: The use of cationic surfactants in the cleaning solution should be avoided, because if used, it may cause irreversible contamination of the membrane element.

Common pollutants and their removal methods:

1. Calcium carbonate scale

When the scale inhibitor addition system fails or the acid addition system appears to cause the pH of the feed water to increase, then calcium carbonate may be deposited. The occurrence of calcium carbonate scale precipitation should be detected as early as possible to prevent the growth of crystals from damaging the membrane surface If calcium carbonate scale is found early, it can be removed by lowering the pH of the feed water to 3.0 to 5.0 for 1 to 2 hours. For calcium carbonate scale with longer precipitation time, RT-818A cleaning solution should be used for circulating cleaning or soaking overnight.
Note: Make sure that the pH value of any cleaning solution is not lower than 2.0. The cup may damage the RO membrane element, especially when the temperature is high, and the highest pH should not be higher than 11.0. Check the use of ammonia to increase the pH, use sulfuric acid or hydrochloric acid to lower the PH value.

2. Calcium sulfate scale

RT-818B cleaning agent is the best way to remove calcium sulfate scale from the surface of reverse osmosis membrane.

3. Metal oxide scale

The method of removing calcium carbonate scale described above can be used to easily remove the deposited hydroxide (such as ferric hydroxide).

4. Silica scale

For silicon scales that are not symbiotic with metallization or organic matter, they can only be removed by special cleaning methods. Please contact the company for detailed methods.

5. Organic deposits

Organic deposits (such as microbial slime or mildew) can be removed with RT-818C cleaning agent. In order to prevent reproduction, a sterilizing solution approved by Hyde Energy can be used to circulate and soak in the system. It usually takes a long time to soak. Effective, if the reverse osmosis device is shut down for three days, it is best to use disinfection treatment, please consult with the company to determine the appropriate fungicide.

6. Cleaning solution

It is recommended to use RT-818 series RO membrane system cleaning agent when cleaning reverse osmosis membrane elements. It is very important to determine the chemical analysis of contaminants before cleaning. Detailed analysis and comparison of the analysis results can ensure the selection of the best cleaning agent and cleaning method. The cleaning method and the cleaning effect obtained during each cleaning should be recorded. Provide the basis for finding the best cleaning method under water supply conditions.

For inorganic contaminants, RT-818A is recommended. It is recommended to use RT-818B for calcium sulfate and organic matter pollution. For severe organic contamination, RT-818C is recommended. All cleaning can be carried out at a maximum temperature of 40 degrees Celsius or below for 60 minutes. The amount of supplies required is calculated based on the amount added per 100 gallons (379 liters). When preparing the cleaning solution, add drugs and cleaning water in proportion, and use free chlorine. The reverse osmosis product water to prepare a solution and mix well.

During cleaning, the cleaning solution is circulated on the high pressure side of the membrane at a low pressure and a large flow rate. At this time, the membrane element is still installed in the pressure vessel and a special cleaning device is needed to complete the work.

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