Filtrasjonstrinn

Filtrasjonstrinn (filtration stages) refers to the division of a filtration process into discrete steps, each designed to remove specific classes of contaminants and to protect subsequent stages. In water and air treatment, the stages commonly proceed from coarse to fine filtration, and from particulate removal to adsorption of dissolved substances. The approach improves reliability, reduces fouling, and simplifies maintenance by allowing targeted media replacement.

A typical sequence begins with prefiltration that removes large particulates, sediment, and debris using screens or coarse cartridge filters. Next is depth filtration, where a porous medium such as sand, anthracite, or graded media traps smaller particles and reduces turbidity. If needed, fine filtration or membrane filtration follows, including microfiltration or ultrafiltration to remove bacteria, pathogens, and fine colloids. Activated carbon may be used between or after depth and membrane stages to remove taste, odor, and organic compounds. The final filtration stage, sometimes called polishing filtration, aims to remove any remaining particulates and residual contaminants to meet target water quality before disinfection.

The design of filtrasjonstrinn involves selecting media with appropriate porosity, determining flow rates, and planning backwash or cleaning cycles to restore performance. Operation must balance filtration efficiency with pressure loss and energy use. While filtration stages are central to the process, disinfection and sometimes chemical treatment typically follow filtration.

Applications include drinking water treatment, wastewater polishing, industrial process water, food and beverage production, and air filtration in HVAC systems.