As water regulations change over time and require increased levels of treatment, it often comes down to two types of filtration: Media Filtration and Membrane Filtration. What is the difference between media and membrane filtration in commercial applications? The key difference between membrane filtration and media filtration is application. Learn how their differences affect the type of filter you need for your industrial and commercial applications.
How Media Filtration Works
Media filtration is the physical capture of pollutants and adsorption of pollutants through chemical reaction. Commonly, media filtration systems are composed of sand, organics, stone, or other similar materials. Carbon is also a common media found in these types of filtration systems. It comes in a block form and provides a faster filtering process than sand filters. Media filters work by having the water pass over and through the media (this occurs many times, as needed). The pollutants become trapped in the voids of the media particles and on the surfaces of the media particles. Another way media filtration works is the pollutants are removed through chemical and molecular action, or cation exchange. This process is commonly used in media filters that target nutrient and metal removal. To be as successful as possible in pollutant removal with media filtration, it is important to know the goals in order to select the appropriate media gradation and composition.
Media filtration is used by municipal drinking water systems, stormwater filtration, sewage and wastewater applications, and in the oil and gas industry. The media for each use may vary some, but sand, gravel, and natural stone fiber are common among all uses.
How Membrane Filtration Works
Membrane filtration requires a permeable layer or sheet of material which the water passes through to remove the pollutants or targeted impurities. Like media filtration, membrane filtration has two removal mechanisms: physical blockage of particles by the membrane material and the removal of substances that are attached to the particles captured during the primary removal process.
Membrane filters are manufactured using a wide variety of materials. Pore size and durability are two key factors for selecting a material. Pore size refers to the hole or gap in the membrane material. Smaller pore sizes can block more particles from passing through the membrane.
Membrane filtration offers a variety of uses with its four categories: microfiltration, ultrafiltration, nanofiltration, and reverse osmosis filtration. Microfiltration has the largest pore size while reverse osmosis membranes are non-porous. During several different processes, microfiltration and ultrafiltration are often used as a pre-treatment step for filtration systems with a finer pore.
Filtration membranes are applied to liquid filtration during processes such as biomass removal, bacteria removal, waste water treatment, slurry concentration, and gas filtration.
The Differences Between Membrane and Media Filtration
The main differences between membrane and media filtration come down to the application. Both processes filter our pollutants. Both processes have two common methods for filtering. Membrane filtration sets itself apart in that it doesn’t use a chemical process to filter water. If your application can’t use a chemical process or method, you may need to consider using membrane filtration. Using media filtration, you may need to filter the same batch of water multiple times to ensure that the media has captured the pollutants to the level you desire.