Dybdefiltre

Dybdefiltre, literally “deep filter” in Danish and Norwegian, designates a filtration method in which solids are removed as liquid passes through a porous medium, with most particles captured within the depth of the bed rather than on the surface. This distinguishes depth filtration from surface filtration, where a cake or screen forms on the media.

In depth filtration, the removal mechanisms are a combination of mechanical straining, diffusion into pore spaces, and adsorption onto the media surfaces. The filter bed provides a high dirt-holding capacity and a smoother pressure drop over time, but it requires periodic backwashing to restore porosity and flow characteristics.

Media for dybdefiltre are typically arranged in layers or mixed beds, including materials such as anthracite, silica sand, garnet, and activated carbon. The choice and order of media are tuned to target particle size distribution and water quality. Dybdefiltre systems are used as pretreatment or polishing steps in municipal drinking-water treatment, industrial process water, and various filtration applications in food, beverage, and mining industries. Flow rates, bed depth, and backwash cycles are selected to balance filtration efficiency, head loss, and operational costs. In backwashing, the flow is often reversed to lift and remove accumulated solids from the bed.

Origin and terminology reflect early to mid-20th-century developments in filtration science, with the term being common in Danish- and Norwegian-speaking contexts. See also depth filtration, media filtration.