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What is Membrane Biofouling? What are its Effects?
According to a 2012 Membranes journal article, “Biofouling of Water Treatment Membranes: A Review of the Underlying Causes, Monitoring Techniques, and Control Measures,” nearly 50% of fouling issues in nanofiltration and reverse osmosis systems are caused by biofouling.
Some of the consequences of this issue include:
- Decreased membrane flux
- Higher feed and differential pressure requirements
- Shorter membrane lifetime and degradation
- Poor water quality and consistency
- Increased energy and pressure demand
There are quite a lot of factors that influence how well organisms will adhere to a specific membrane, as can be seen in the table below:
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Monitoring Parameters to Detect Biofouling
Proper system monitoring is critical to detecting membrane biofouling early on and avoiding its harmful effects. There should be a constant monitorization of the following parameters:
- ATP testing or microbial plating of the water and membrane surfaces
- Total Organic Carbon (TOC) content in the water
- Pressure changes
- Salt concentrations post-filtration
Pre-treatment Technologies to Minimize Biofouling
Pre-treatment technologies are used before the membrane systems to reduce the bioburden and lower the frequency and severity of biofouling. Some of the most common pre-treatment technologies include:
- Chlorination: a standard pre-treatment technology used to minimize biofouling. Although many membranes are now more resistant to chlorine, oxidizing agents such as chlorine can still degrade the membrane surface over time. Chlorination also creates by-products such as NDMA, THMs, and HAAs, which are suspected carcinogens and unwanted in the beverage industry.
- Ozonating is another effective pre-treatment technique used to reduce biofouling. However, there is a need to remove residual ozone from the water before it comes into contact with the membranes. Ozonating also creates by-products, such as bromates, a concern in the bottled water industry.
- UV disinfection is a low-maintenance solution that uses irradiation instead of oxidation to disinfect water. UV disinfection does not create unwanted by-products and does not harm the polymeric surface of the membranes. In addition, UV disinfection offers online performance monitoring to provide additional reassurance that the system is performing correctly. As a result, UV disinfection is one of the most effective pre-treatment solutions for the biofouling risk.
Why UV Disinfection is the Best Option for Minimizing Biofouling
UV disinfection is a low-maintenance, online system performance monitoring solution that offers numerous benefits over chlorination and ozonation. Unlike these oxidizing agents, UV uses irradiation instead of oxidation, so there is no residual impact on the membrane surface or creation of by-products such as NDMA, THMs, HAAs, and bromates. In addition, UV disinfection offers the added advantage of real-time system monitoring, reassuring that the system is operating correctly.
Conclusion
Biofouling is a common issue that can negatively impact the performance of membrane systems in the food and beverage industry and pharmaceutical industries. Monitoring parameters and implementing effective pre-treatment technologies can help minimize this problem. UV disinfection for industries such as pharmaceuticals is the best choice of the pre-treatment options available due to its low-maintenance, online system performance monitoring, and lack of residual impact on the membrane surface or by-product formation.
A full copy of the article “Biofouling of Water Treatment Membranes: A Review of the Underlying Causes, Monitoring Techniques, and Control Measures” can be found at: https://www.sciencetheearth.com/uploads/2/4/6/5/24658156/2012_nguyen_biofouling_of_water_treatment_membranes.pdf
Nuvonic
Date 13/08/2023
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