99% Of People Do Not Know The Specific Method Of Reverse Osmosis Membrane Cleaning

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The pore size of reverse osmosis membrane is very small, so it can effectively remove dissolved salts, colloids, microorganisms, organics and so on. The long-term application of reverse osmosis membrane will cause membrane pollution, so it is very important to be familiar with the specific methods of reverse osmosis membrane cleaning. Now, as a small editor who has worked in the industry for many years, let's share the cleaning methods of reverse osmosis membrane.

The main reason for the performance decline of reverse osmosis membrane is that the membrane surface is polluted, such as surface scaling and membrane surface blockage; Or caused by the physical and chemical changes of the membrane itself. The physical change is mainly due to the decrease of membrane permeability caused by compaction effect; Chemical changes are mainly caused by pH fluctuations. For example, hydrolysis of cellulose acetate membrane and free chlorine will also deteriorate the performance of aromatic polyamide membrane.

The main causes of reverse osmosis membrane fouling and blockage are the deposition of membrane surface and the growth of microorganisms. Microorganisms not only block the membrane, but also erode and damage cellulose acetate. Therefore, a certain amount of residual chlorine must be maintained in the membrane, but the residual chlorine is too high, which will lead to the decline of membrane performance. Therefore, the residual chlorine in front of cellulose acetate membrane shall be maintained at 0.1 ~ 0.5 mg / L, while the residual chlorine in front of aromatic polyamide membrane shall be less than 0.1 mg / L.

The cleaning treatment of reverse osmosis membrane is a meticulous and complicated work. At present, the quality of domestic membrane is not high enough, and the membrane is easy to be damaged after repeated cleaning. In order to reduce the cleaning work, we should do a good job in pretreatment and control the water quality.

The treatment method is to periodically wash with 0.1% formaldehyde solution or 100 mg / L Bromogeramine disinfectant for at least 1 hour. The contaminated membrane shall be cleaned with 2% ammonium citrate solution (pH 4 ~ 8), or sodium bisulfite, sodium hexametaphosphate and dilute hydrochloric acid shall be used to prevent the scaling of manganese, iron and carbonate. Sometimes the organic matter is also cleaned with enzyme detergent. The cleaning pressure is controlled at 0.34 ~ 0.98 MPa, and the cleaning flow rate is 2 ~ 3 times of the original water treatment flow rate.