Membrane Filtration: Microfiltration
One type of membrane filtration used in water treatment utilizes a semi-permeable membrane to separate unwanted materials from the water. The membranes have pores of different sizes which allow water to pass through but prevent certain other materials from passing through with it, thus separating those materials out of the water. There are several different types of membranes, and each has its own pros and cons. In this series of blogs on membrane filtration, we will discuss the benefits and drawbacks of reverse osmosis, nanofiltration, ultrafiltration, and microfiltration so that you can gain a better understanding of the similarities and differences of each and determine which might be best for you.
What is Microfiltration?
Microfiltration (MF) membranes usually have some of the largest pores of the commonly used filtration membranes that we will discuss in this blog series. They are often used as a pre-treatment step to remove larger contaminants from the water before sending it through a finer filter, depending on the desired level of separation. They can usually remove such materials as sediment and suspended solids, and larger biological growth like algae and some bacteria. They cannot, however, remove smaller or microscopic materials like viruses or multivalent or monovalent ions.
Advantages and Disadvantages
Because microfiltration is a physical separation process, it can remove contaminants from water without the need for harsh or expensive chemicals. Its larger pore size makes it excellent for a ‘first pass’ filtration, to partially filter water before sending it on for further filtration, such as ultrafiltration or reverse osmosis. It can be used in the food industry to clarify liquids, like fruit juice, and has usefulness in other applications that don’t require fine filtration. The major disadvantage of microfiltration is the fact that its large pore size cannot separate microscopic materials from water.