Painesuodatus

Painesuodatus is the Finnish term for pressure filtration, a filtration method that uses applied pressure to drive a liquid through a porous medium or a semipermeable membrane in order to separate suspended solids from a liquid. It is used in a variety of industries, including water and wastewater treatment, mining, food and beverage, and pharmaceutical manufacturing.

The process relies on the pressure difference across the filtration medium to force filtrate out of the slurry while solids are retained as a cake on the surface or by a membrane. Filtration rate and efficiency depend on the applied pressure, the pore size or membrane characteristics, the properties of the slurry, temperature, and the behavior of the filter cake. In membrane-based forms, transmembrane pressure is the main driving force for separation.

Common equipment and configurations include filter presses and plate-and-frame filters for dewatering sludges, as well as membrane systems such as microfiltration and ultrafiltration that operate under pressure. Cross-flow filtration, where the feed streams along a channel and pressure maintains flow through a selective barrier, is another widely used variant. The choice of method depends on desired filtrate quality, solids content, and process economics.

Advantages of paine-suodatus include the ability to achieve high solids recovery and suitability for continuous operation, making it attractive for large-scale processing. Limitations can include energy consumption, handling and disposal of the resulting filter cake, and potential fouling or channeling in membranes, which may require pretreatment or regular cleaning.

Etymology: the term derives from paine (pressure) and suodatus (filtration). It is related to other filtration methods such as gravity or vacuum filtration and to membrane-based techniques.