Maintenance and Cleaning Methods for Ultrafiltration Membranes

Figure 1 Ultrafiltration membrane

The term ultrafiltration membrane is believed to be familiar to everyone in the water treatment industry. It has special hydrophilic properties and can obtain high water flow under ultra-low pressure, ultra-high filtration accuracy, and strong mechanical hardness. It is a relatively stable water treatment product.

After operating for a certain period of time, a good product needs to be cleaned to ensure that the ultrafiltration membrane works properly. Maintenance is also critical, and in this article, we share several cleaning methods related to ultrafiltration.

Some users may purchase ultrafiltration membranes for replacement in advance. The ultrafiltration membrane is the core part of the ultrafiltration equipment. If it is not protected properly and damaged, it will affect the quality of the produced water.

It is recommended that unopened ultrafiltration UF membranes be immersed in membrane protection solution and sealed before use to prevent membrane pore shrinkage and damage to the membrane performance, which may lead to a decrease in water quality.

Figure 2 Ultrafiltration equipment

What Maintenance Methods Should Be Taken Into Account When The Ultrafiltration Equipment Is Not Used?

1. If the ultrafiltration membrane is not used for less than 10 days, it should be back washed with 15 ppm (ml/L) of HY-240 sterilizing agent and disinfected. Then, the inlet valve, outlet valve, and regulating valve of the ultrafiltration membrane should be closed to maintain the sealing and disinfection of the ultrafiltration membrane for short-term maintenance use.

2. If the UF membrane is not used for more than 10 days, it must be disinfected and backwashed once, and then HY-310 protective liquid should be added to the ultrafiltration membrane and sealed for long-term maintenance use.

After using the membrane for a period of time, to prolong its service life, the ultrafiltration membrane must be regularly cleaned. This can also prevent the ultrafiltration membrane from being contaminated and ensure smooth filtration of the ultrafiltration membrane.

There are many methods for cleaning ultrafiltration membranes, including conventional physical methods and chemical methods for removing difficult-to-remove substances.

Normal Maintenance and Cleaning Methods For Ultrafiltration Membranes

Sponge ball cleaning: Choose a sponge ball that is the same diameter as the membrane tube, and repeatedly wipe the membrane tube using a pipe. The sponge ball can be reused.

Hot water flushing: Heat the water to 30-40°C and flush the membrane surface. This method is effective for removing viscous or thermo-soluble impurities.

Chemical cleaning of ultrafiltration membranes requires selecting the corresponding chemical agents based on the type of pollutants to achieve cleaning effects.

Alkaline solution cleaning: NaOH is a commonly used base. The pH of the prepared solution is about 10-12. After the water circulation operation, the membrane can be cleaned or soaked for 0.5-1 hour before cleaning. It can effectively remove impurities and oils.

Oxidant cleaning agents: H202 and NaC10 are commonly used sterilizing agents for ultrafiltration membranes. Choose a 1%-3% H202, 500-1000 mg/L NaC10 water solution for cleaning. It is effective for dirt and disinfecting bacteria.

For protein precipitation in the food industry, gastric enzymes or phosphates and silicate-based alkaline detergents are selected for cleaning, and disinfection is required (using NaOH and H202, etc.).

The chemical cleaning method is similar to the normal cleaning process of ultrafiltration membranes. Pour the corresponding cleaning solution into the original liquid inlet, which will automatically penetrate into the concentrated layer and return to the cleaning liquid container. After a cycle, the cleaning solution is discharged, and then clean water is used for flushing.

Developing a habit of regularly cleaning ultrafiltration membranes not only maintains the membrane system and ensures water quality standards, but also does not shorten the life of the membrane.

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