Sulfate
Source of Sulfate
Sulfate (SO
4) occurs in almost all natural water. Most sulfate compounds originate from the oxidation of sulfite ores, the presence of shales, and the existence of industrial wastes. Sulfate is one of the major dissolved constituents in rain. High concentrations of sulfate in drinking water causes a laxative effect when combined with calcium and magnesium, the two most common components of hardness. Bacteria, which attack and reduce sulfates, causes hydrogen sulfide gas (H
2S) to form. Sulfate has a suggested level of 250 mg/i in the Secondary Drinking Water Standards published by the US EPA.
Treatment of Sulfate
Reverse osmosis will reduce the sulfate content by 97 - 98%. Sulfates can also be reduced with a strong base anion exchanger, which is normally the last half of a two-column deionizer.