A divalent cation. Magnesium can account for about a third of the hardness in a brackish water, but can have a concentration five times higher than calcium in sea water. The solubility of magnesium salts is high and typically does not cause a scaling problem in RO systems. [....]
Iron is a water contaminant that takes two major forms. The water-soluble form is known as the ferrous state and has a + 2 valence state. In non-aerated well waters ferrous iron behaves much like calcium or magnesium hardness in that it can be removed by softeners or its precipitation in the back end of the RO system can [....]
The solubility of sparingly soluble salts increases with increasing feed TDS. To account for this effect in calculating the solubility of a salt (e.g. calcium sulfate, barium sulfate, strontium sulfate or SDSI), the Ionic Strength of a water is calculated. The Ionic Strength of each ion is derived by taking the ppm concentration of each ion (as calcium carbonate) [....]
Hydrogen sulfide is a gas that causes the noticeable "rotten egg" smell in feed waters, with a threshold odor level of 0.1 ppm and a noticeable offensive odor at 3-5 ppm. Hydrogen sulfide is readily oxidized to elemental sulfur by oxidants (e.g. air, chlorine or potassium permanganate). Sulfur acts as a colloidal foulant and has a history of not [....]
Ion Exchange and boiler water chemists frequently report the concentration of hardness as "Grains per Gallon (as calcium carbonate equivalents)". One Grain per U.S. Gallon (as calcium carbonate) is equal to 17.1 ppm (as calcium carbonate). [....]
A monovalent anion. Fluoride is found naturally at low levels in some well waters, but normally its presence is due to injection into municipal water to provide a residual up to 2.5 ppm for the control of dental caries. Fluoride levels in potable waters above 5 ppm can cause mottled and brittle teeth. The rejection of fluoride by a [....]