Fluoride in Ohio Water Supplies—Its Effect, Occurrence and Reduction

De-fluoridation of groundwater using magnesium oxide

“…Fluoride removal by lime precipitation was found to be very difficult when fluoride concentration was below 20 mg/l (Rabosky andMiller 1974 as mentioned in Vigneswaran andVisvanathan 1995). However, there are considerable indications that higher levels of fluoride removal by lime is possible when sufficient amount of magnesium is present or added, and that the extent of fluoride removed varies as a function of the amount of magnesium precipitated as Mg(OH) 2 from the water (Scott et al 1937, Sorg 1978as mentioned in Chinn 2003Rohrer 1971 as mentioned in Liu andLipták 1999). According to Sorg 1978(as mentioned in Chinn 2003 79 mg/l of magnesium is needed to reduce fluoride from 4 to 1.5 mg/l.…”

Some Recent Developments in Water Works Practice

“…More and more attention is being paid to the presence of fluorides in natural water supplies. Surveys of fluorides in waters in Middle Western states have been reported in Illinois (8), Iowa (9), Ohio (10) and Wisconsin, and in some of the Western states, such as Kansas (11). In none of these states is the mottled enamel resulting from the presence of fluorides considered severe, but the fact that it exists at all has heretofore not been widely realized.…”

“…Weart and Klassen (8) suggest that the solution of the problem offers a challenge to the water works profession. To answer this challenge it has been reported that fluorides are most easily removed in the lime soda process of water softening, particularly when the water is high in magnesium (10). The process is reported to be economical when the fluorides do not exceed 3.5 p.p.m.…”

Removal of Salts from Water

“…Negative ions other than carbonate and bicarbonate can be removed by anion exchangers first described by Adams and Holmes in 1934. 5. The best anion exchangers are now produced from resins derived by condensing aromatic amines with aldehydes and acids or by halogenating suitable bodies by amination.…”