Bed

the ion exchange or filter media in a column or other tank or operational vessel.

Definitioner

Media: the selected materials in a filter that form the barrier to the passage of certain suspended solids or dissolved molecules.
Ion Exchange: a reversible process in which ions are released from an insoluble permanent material in exchange for other ions in a surrounding solution; the direction of the exchange depends depends on the affinities of the ion exchanger for the ions present, and the concentrations of the ions in the solution.
Ion: an atom, or group of atoms which function as a unit, and has a positive or negative electrical charge, due to the gain or loss of of one or more electrons.
Filter: specifically, a device or system for the removal of solid particles(suspended solids); in general, includes mechanical, adsorptive, oxidizing, and neutralizing filters.