Home > Encyclopedia of Science > Filtration

• Liquid filtration
• Words to Know
• Clarifying filters
• Gas filtration

Filtration is the process by which solid materials are removed from a fluid mixture, either a gas or liquid mixture. Anyone who has ever prepared foods in a kitchen has probably seen one of the simplest forms of filtration. After cooking pasta, for example, the contents of the pot may be poured through a colander or sieve. (A colander looks like a big pot with holes in it.) The pasta is captured in the colander, and the wastewater runs through holes and is usually thrown away.

Beginning science students often use filtration, too. The solid material (precipitate) formed in a chemical reaction can be separated from the liquid part of a mixture by passing the mixture through a filter paper. The filter paper...