For 10 points, identify this technique often performed by water purification systems.
One type of this technique uses either a Buchner or a Hirsch funnel, and cannot be used if the solvent has a low boiling point as it will evaporate before this technique can be finished. A second kind of this technique uses the "fluted" form of a special kind of paper. This process, including the aforementioned "vacuum" and "gravity" types, is designed to remove solutes from solution by forming small pores that liquids can pass through but not solids. For 10 points, identify this technique often performed by water purification systems.
One type of this technique uses either a Buchner or a Hirsch funnel, and cannot be used if the solvent has a low boiling point as it will evaporate before this technique can be finished.
{filtration} [accept equivalent answers such as {filtering}]