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What Are The Cleaning Methods For The Membrane?
- Aug 03, 2018 -

What are the cleaning methods for the membrane?


In the operation process of the membrane separation device, the most common and most serious problem is the problem that the water permeability is reduced due to the contamination or clogging of the membrane. Therefore, the membrane cleaning and the cleaning process are important steps of the membrane separation method, and the cleaning membrane is extended. The service life is directly related to the separation performance of the water flux of the recovery membrane. When the permeate water volume or the effluent water quality of the membrane is significantly decreased or the membrane unit inlet and outlet pressure difference exceeds 0.05 MPa, the membrane section must be cleaned.


There are two main types of membrane cleaning methods: physical methods and chemical methods. In the specific operation, the cleaning method should be selected according to the configuration of the module, the material of the membrane, the type of pollutants and the degree of contamination.


The physical cleaning method uses mechanical force to remove contaminants from the surface of the membrane, and no chemical reaction occurs during the cleaning process. The specific methods mainly include hydraulic flushing, gas-water mixed flushing, countercurrent cleaning, and hot water washing. The hydraulic cleaning is a soft impurity accumulated on the high-flow film formed by decompressing the membrane concentrated water side. The gas-water mixed cleaning is to pass the compressed air and water flow on the side of the concentrated water of the membrane, and the surface impurities of the membrane are cleaned by the shearing action of the gas, water and the membrane surface. Countercurrent cleaning is mainly used for the cleaning of hollow fiber membranes by applying a reverse pressure to the support layer, causing reverse flow of the membrane permeate to loosen and remove contaminants from the feed side surface of the membrane.


The chemical cleaning method uses a chemical agent to chemically react with harmful impurities on the film surface to achieve the purpose of cleaning the film. Different chemical agents should be used according to different pollutants. The choice of chemical agents must take two points into consideration: one is that the cleaning agent must have good ability to dissolve and decompose the pollutants, and the other is that the cleaning agent can not contaminate and damage the membrane surface. Therefore, it is necessary to determine the cleaning process according to different pollutants, and the working temperature and the film to the cleaning agent are considered to be the pH range and the chemical stability of the body.