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.
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 Exchanger - a permanent, insoluble material which contains ions that will exchange reversibly with other ions in a surrounding solution. Both cation and anion exchangers are used in water conditioning.
Ionization - the process in which atoms gain or lose electrons and thus become ions with positive or negative charges; sometimes used as synonymous with dissociation, the separation of molecules into charged ions in solution.
Ionization Constant - a constant specific for each partially ionizable chemical compound to express the ratio of the concentration of ions from the compound to the concentration of un-ionized compound.
Iron - an element often found dissolved in ground water in concentrations usually ranging from zero to 10 ppm. It is objectionable in water supplies because of the staining caused after oxidation and precipitation, because of taste, and because of unsightly colors produced when iron reacts with tannins in beverages such as coffee and tea.
Iron Bacteria - organisms which are capable of utilizing ferrous iron, either from the water or from steel pipe, in their metabolism, and precipitating ferric hydroxide in their sheaths and gelatinuos deposits. These organisms tend to collect in pipe lines and tanks during periods of low flow, and to break loose in slugs in turbid water to create staining, taste and odor problems.