What is membrane filtration?

Membrane filtration is a separation method that can be used to remove harmful substances from liquids. Various variants of membrane filtration are used in the Netherlands to purify waste water, drinking water and process water, among other things. Membrane filtration is a collective name for various separation processes such as microfiltration, ultrafiltration, nanofiltration and hyperfiltration. PB International uses all these filtration processes in its water filters to remove the legionella bacteria from our water in this way. With the help of membrane filtration, PB International ensures safe and clean drinking water.

Although the variants of membrane filtration filter different microorganisms from liquids, all variants use the same separation method. Membrane filtration is based on the presence of a membrane. The membrane used is, as it were, a selective partition – various substances, particles and / or bacteria can pass through the membrane while others are retained. Every membrane has a specific pore size. All substances, particles, bacteria and viruses that have a larger pore size than the membrane are trapped in the membrane. All substances, particles, bacteria and viruses that have a smaller pore size than the membrane can pass through the membrane.

Feel free to contact us about membrane filtration

Membrane filtration at PB International

Membrane filtration is often used as a separation method in water purification systems. Membrane filtration can prevent the formation and spread of the legionella bacteria. In the Netherlands it is mandatory to remove the legionella bacteria (if present) from the drinking water. Only KIWA-certified products may be used as a separation method according to the Dutch Drinking Water Act. If legionella filters, gatekeeper systems and water filters meet these requirements, they will receive a KIWA BRL K14010-1 certification. All PB International products have this certification, which means that they comply with the laws and regulations of KIWA Netherlands.

Our experience is that a KIWA certification abroad is often sufficient to comply with local laws and regulations.

At PB International, membrane filtration is used in the treatment of waste water, drinking water, process water and groundwater. There are various aspects that are of great importance when designing a water purification system based on membrane filtration. Aspects that can optimize the effect of membrane filtration are:

  • A right choice for the type of membrane. Depending on the current quality of the liquid and the desired final quality, you can choose a type of membrane filtration. PB International can help you with this. After a careful investigation by our advisors, we can tell you whether you should opt for a micro, ultra, nano or hyper filtration process.
  • Much attention for a possible (necessary) pre-treatment and after-treatment of the water purification system and its membranes. To prevent the membranes from being damaged or blocked by sharp or hard (sand) particles, the liquid must first be pre-treated. In this way the membrane is protected in micro, ultra, nano and hyper filtration. The liquid is passed through a fine sieve so that the large parts are removed in advance. There is no standard pre-treatment recipe – after all, every liquid is different. Optimal pre-treatment is determined after an investigation by the advisors of PB International.
  • A correct cleaning method with a frequent rinse and use of the right chemicals. It is possible that the membranes become contaminated during membrane filtration. If a membrane is contaminated, its effect will be less. It is therefore of great importance to regularly flush the membranes. With the help of a frequent flush, all collected substances, particles, bacteria and viruses can be removed from the membrane. Correct rinsing is necessary for micro, ultra, nano and hyper filtration. If you opt for continuous service from PB International, your membranes will undergo an annual check.

Micro membrane filtration at PB International
If micro-membrane filtration is used, a membrane is placed with a pore size of 0.10 to 1.0 micron. The effect of microfiltration at PB International is based on a pressure difference. This pressure difference occurs between the liquid that contains all harmful particles, substances and bacteria, and the filtered liquid. With a required pressure of 0.1 to 2.5 bar, the contaminated liquid is pressed through the membrane. Thanks to the pore size of the membrane, all undissolved substances, particles and bacteria (with a pore size greater than 0.10 microns) will be removed from the liquid. Micro-membrane filtration is often used as pre filter for ultrafiltration.

Ultra membrane filtration at PB International
Ultra-membrane filtration, like micro-membrane filtration, removes dissolved substances in a liquid with the aid of a pressure difference. Where microfiltration is only able to remove bacteria from liquids, ultrafiltration can also remove unresolved viruses from liquids. The membrane of ultra-membrane filtration contains pores with a size of 0.01 to 0.10 microns. With a required pressure of 0.5 to 2.5 bar, the contaminated liquid is pressed through the membrane. With the help of ultra-membrane filtration, PB International is able to completely remove the bacteria from drinking water, without the risk of growth.

Nano membrane filtration at PB International
If nano-membrane filtration is used as a separation method, not only undissolved substances, but also dissolved substances can be removed. Micropollutants and polyvalent ions are removed from the liquid using a membrane with a pore size of 0.01 to 0.001 micron and a required pressure of 5 to 15 bar.

Hyper membrane filtration at PB International
With hyper-membrane filtration, or reverse osmosis, we hardly speak of filtration anymore. Hyperfiltration is very similar to distillation. The hyperfiltration membrane has a pore size of less than 0.001 microns. This pore size is very small, so that a separation based on diffusion takes place. With a required pressure of 10 to 70 bar, both micro-impurities, polyvalent ions (dissolved substances) and single ions (dissolved salts) are removed from the liquid. Only gases and low-molecular substances can (partially) pass through the membrane of hyper-membrane filtration.

Do you want to know more about membrane filtration?
Do you want to know more about the different membrane filtration processes of PB International? Or are you looking for specific information about micro, ultra, nano or hyper filtration? Contact one of our advisers by calling 0314 – 621 465 or by emailing to info@pb-international.com. You can expect a suitable answer within a few working days!

 

 

Feel free to contact us about membrane filtration

 

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