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In reverse osmosis, ultrafiltration, and other membrane technologies for water treatment, one of the most serious problems.

Although mineral scaling and fouling by suspended solids are also significant challenges, microbial growth is considered the number one enemy of membranes because it develops quickly, is difficult to eliminate completely, and generates major operational and economic impacts.

Why is microbial growth so dangerous for membranes?

Biofouling affects water treatment systems on multiple levels:

1. It reduces permeate flow

As the biofilm expands, it clogs the membrane pores, decreasing water production. This is one of the most searched symptoms by operators when investigating “why is my membrane producing less water?”

2. It increases operating pressure

The system needs to work at higher pressure to overcome the resistance caused by attached microorganisms. This means higher energy consumption and increased costs.

3. It promotes corrosion and material degradation

Some bacteria produce acids and compounds that damage the membrane surface and the metallic components of the system.

4. It complicates chemical cleaning

Biofouling is resistant to many traditional chemicals. Biofilms regenerate quickly if cleaning is not performed correctly and with the proper products.

5. It shortens membrane lifespan

It is one of the main reasons operators search for information such as “when to replace a membrane” or “how to extend the life of an RO system.”

How to prevent microbial growth in membrane systems

To avoid this problem, experts recommend:

● Efficient pretreatment

Including filtration, activated carbon, microfiltration, and preliminary disinfection.

● Chlorine and disinfectant control

Removing free chlorine is essential to protect reverse osmosis membranes, but it must be replaced with compatible biocides to maintain microbiological control.

● Scheduled chemical cleanings (CIP)

Using specific products to remove bacteria, enzymes, and biofilms.

● Constant monitoring

Parameters such as SDI, turbidity, microbiological load, and differential pressure should be checked regularly.

Conclusion

Microbial growth not only reduces system efficiency but also increases operating costs and shortens membrane lifespan. For any industry that relies on water treatment, controlling biofouling is key to ensuring continuous operation, permeate quality, and long-term system sustainability.