filtermedium

Filter medium, or filter media, is the material through which a fluid passes in a filtration system to remove particulates, dissolved substances, or microbes. The medium forms a porous barrier that retains contaminants by mechanisms such as straining, adsorption, ion exchange, or chemical reactions. Filter media are selected based on compatibility with the fluid, desired contaminant removal, flow requirements, and durability. They can operate as depth filters, which capture particles throughout a thick, porous layer, or as surface filters, where contaminants are retained on or near the surface of the media.

Common types include granular media such as sand, anthracite, activated carbon, zeolites, and diatomaceous earth; plus ceramic and glass fiber media. Other configurations use polymeric membranes or pleated media that function as surface filters with defined pore sizes. The choice depends on the application, required removal mechanisms, and maintenance considerations.

Examples across industries: In municipal water treatment, rapid gravity filtration uses layers of sand with a supporting material such as anthracite and sometimes garnet, while activated carbon removes taste and odor; ion-exchange resins can be used to remove hardness and specific contaminants. In air filtration, media such as glass fibers, cellulose, and synthetic polymers (often in pleated configurations) capture particulates and adsorb gases.

Maintenance and performance: Media can become fouled and require cleaning or replacement. Depth media are typically cleaned via backwashing; resin and some carbon media may be chemically regenerated or replaced. Disposal and regeneration considerations influence lifecycle costs and environmental impact.