Filtration is a physical process that separates particles from a fluid by passing the fluid through a porous medium that traps the particles. The process is used in a wide variety of applications, including water purification, air pollution control, and food processing.
The earliest known use of filtration dates back to ancient Greece, where Hippocrates described a method for filtering water using a cloth. However, it was not until the 19th century that the scientific principles of filtration were fully understood. In 1828, the Scottish chemist Thomas Graham developed a quantitative theory of filtration, and in 1855, the English physicist John Tyndall developed a method for measuring the size of particles using filtration.