What is Membrane Filtration?
There are a variety of methods used to filter unwanted substances from liquids. One popular method is called membrane filtration and it is used in a number of ways from treating contaminated water to filtering food products as part of the refining process. There are several different types of membrane filtering methods, but all of them have the end goal of creating a clean filtered liquid. Several companies around the world specialize in this type of technology and provide the systems for performing filtration as well as replacement parts and membranes.
Membrane filtration works by passing a liquid through a semi permeable membrane. The permeability of the membrane is determined by the pore size of the membrane and the choice of membrane pore size will determine what types and sizes of particles can be filtered. The membranes pores allow the liquid to pass through while trapping the larger particles and the end result is clean filtered liquid on the other side of the membrane. Because the membrane is trapping particles it will need to be cleaned and occasionally replaced to continue functioning properly.
Some common types of membrane filtration are reverse osmosis, ultra filtration, micro filtration and nanofiltration. The type of membrane filter used is dependent on the size of the particles that need to be removed from the liquid. The membranes are carefully designed to remove unwanted particles while allowing for optimum efficiency and flow through rate. Membrane filters can remove particles as small as 0.2 microns, including the water borne parasites giardia and cryptosporidium.
Industry is a heavy user of membrane filtration techniques due to its low cost and low energy requirements. A membrane filter can be designed to run with almost no energy input, by using a gravity fed pressurized system that feeds liquids through the membrane at a set rate. There are also no chemicals required when treating liquids with a membrane filter, which makes this type of filtering system very attractive to food manufacturers and the medical industry.
In many industrial uses a process known as successive membrane filtration is used. This type of membrane filter uses a series of membranes in which the pore size becomes progressively smaller, thus removing more impurities from the liquid with each pass through a smaller filter. The benefit of using a membrane filtering system such as this is that the membranes are less prone to clogging since each membrane is only removing a small part of the particles. It also has the benefit of being able to fit into a small space because when using numerous membranes each one can be made smaller and still operate efficiently.
Membrane filters are quite easy to set up and use and there are a variety of industries that use and benefit from membrane filtration systems. The only caveat is that the systems must be maintained properly through regular cleaning and replacement of the membranes to continue operating effectively. You can find membrane filters in use in the food processing, waste management, laboratory science, water treatment and medical industries among others.