filtratie

Filtration is a physical separation process in which a fluid passes through a porous barrier that retains solids or certain dissolved substances. The fluid that passes through is called the filtrate, while the material left behind is the retentate. Filtration is used to clarify liquids, remove particulates, or separate mixtures and is a common unit operation in chemistry, environmental engineering, food and beverage production, and healthcare.

Filtration methods vary by mechanism and medium. Depth filtration uses a thick porous medium (such as cloth, paper, or packed beds) to capture particles throughout its depth, often providing high dirt-holding capacity. Surface filtration uses a thin barrier, typically a membrane, where particles are retained at the surface. Filtration can be gravity-driven or aided by vacuum, pressure, or centrifugal force. Filter media range from coarse sand or cellulose to paper filters, activated carbon, ceramics, and polymer membranes.

Membrane filtration categories are defined by pore size and separation mechanism. Microfiltration removes larger particles and microorganisms; ultrafiltration removes larger macromolecules; nanofiltration targets small ions and solutes; reverse osmosis removes nearly all dissolved species but requires high pressure. These membrane processes are widely used in water treatment, food and dairy, pharmaceuticals, and biotechnology.

Applications and considerations: Filtration is used to purify water and air, sterilize beverages and medicines, and prepare samples in laboratories. It may require pretreatment to prevent fouling, and filters must be cleaned or replaced. Fouling, flow rate, pressure, temperature, and chemical compatibility influence design and operating costs.