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Influencing factors of ultrafiltration operation

Oct 04, 2020

1. Operating pressure: The relationship between the permeation flux of the ultrafiltration membrane and the operating pressure depends on the properties of the membrane and gel layer. The ultrafiltration process is a gelation model, and the membrane flux has nothing to do with pressure. The flux at this time is called the critical flux. The actual ultrafiltration operation should be carried out near the JX flux, when the operating pressure is about 0.5 to 0.6 MPa. In addition to overcoming the resistance through the membrane and gel layer, it must also overcome the flow and local head loss.

2. Temperature: The operating temperature mainly depends on the chemical and physical properties of the material being processed. Because high temperature can reduce the viscosity of the material liquid, increase the mass transfer efficiency, and increase the permeation flux, it should be operated at the allowable Z high temperature.

3. Operating cycle: As the ultrafiltration process progresses, a gel layer is gradually formed on the surface of the membrane, so that the permeation flux gradually decreases. When the flux reaches a certain low value of Z, it needs to be cleaned. This period of time is called It is a running cycle. The change of the operating cycle is related to the cleaning situation.

4. Feed concentration: With the progress of the ultrafiltration process, the concentration of the main stream gradually increases. At this time, the viscosity increases, which increases the thickness of the gel layer, thereby affecting the flux. Therefore, the allowable concentration should be set for the main liquid flow.

5. Material and liquid treatment: In order to increase the permeability of the membrane and ensure the normal and stable operation of the ultrafiltration membrane, the material and liquid should be treated and treated as needed. Commonly used pretreatment methods include precipitation, coagulation, filtration, and adsorption.

6. Membrane cleaning: The membrane needs to be cleaned regularly to maintain the permeation flux and extend the service life of the membrane.