Common problems and solutions of nanofiltration membranes

Release Time:

2022-02-17 09:26

Nanofiltration membrane is a relatively common product in the water treatment industry. It can filter, separate and purify many substances, so it has been used in many industries and has played a good role. Recently, Xiaobian found in sorting out user feedback information that many users do not know enough about nanofiltration membranes, and there will be some problems during use, which will affect the operation of the system, so the intimate Xiaobian will summarize some common problems of nanofiltration membranes and Approach:

1. Sudden increase in conductivity

One reason is that the water source is suddenly polluted. Solution: Immediately stop water production and use biological cleaning in time.

The second reason is that the membrane element is destroyed after chemical cleaning. Solution: If the conductivity is not high, it can continue to be used. If the conductivity is too high, it can only be scrapped.

The third reason is that the water pressure is too large and the membrane is broken down. Solution: replace with new membrane.

2. White flocs, floating objects and green moss appear in the finished water

The reason is that this is not a problem with the membrane, but the pipeline and the finished water tank have not been sterilized and cleaned for a long time.

Solution: The problem of cleaning the pipeline and the finished water tank will be eliminated.

3. The water output suddenly decreases

The first reason is that the membrane is blocked. The solution: biological cleaning is recommended.

The second reason is that the front water treatment system is blocked, resulting in insufficient water supply. Solution: It is recommended to replace quartz sand, activated carbon, and PP cotton.

4. The new membrane or the membrane after biological cleaning has abnormally high conductivity or no water

The reason is that the water seal at the end of the membrane or the water seal at the indirect part is damaged, and the membrane may be installed backwards if there is no water. The solution is to replace the water seal and install it correctly.

5. Causes of damage to nanofiltration membranes

Microbial contamination: When microbial contamination occurs, the permeation rate of the reverse osmosis equipment and the total number of bacteria in the concentrated water are at a high level, which has a lot to do with the lack of careful maintenance and disinfection.

Colloid pollution: When colloid pollution occurs, there are usually two characteristics. One is that the microfilter is quickly blocked in the pretreatment, especially the pressure will increase rapidly. The second is that the SDI value exceeds 2.5.

6. How many years can the nanofiltration membrane element generally be used?

The service life of the nanofiltration membrane depends on the chemical stability of the membrane, the physical stability of the membrane element, the cleanability, the influent water source, the pretreatment, the cleaning frequency, and the level of operation and management.

7. New storage method for nanofiltration membrane modules

The new nanofiltration membrane module is filled with glycerol as a protective solution, which should be washed with lye before use, and then washed with alkali/chlorine to wash away the glycerol. The new membrane modules should be kept in the original packaging until before installation. The modules should be stored indoors and avoid direct sunlight according to the following requirements: Storage temperature is 10-30℃, storage humidity is lower than 70%, and storage is in a horizontal position.

8. Storage method of used nanofiltration membrane modules

The used nanofiltration membrane modules should be cleaned before storage, and any one of the following solutions should be used as a protective solution

1. 80~100% glycerin.

2. Phosphoric acid with pH in the range of 2-3.

3. Benzoic acid or sodium benzoate with a concentration of 1000ppm.

4. The concentration is 1000~5000ppm sodium bisulfite or sodium metabisulfite.

The above summarizes some of the problems and solutions that nanofiltration membranes will encounter when using them, hoping to help everyone. During normal use, it is still necessary to pay attention to the maintenance of the membrane element, in order to more effectively prolong the service life of the membrane element.

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