Removal of boron and fluoride from water

A process for reducing fluoride ion of feed water containing fluoride ion, the process comprising adjusting the pH of the feed water with an alkaline hydroxide to at least about 10.2 in the presence of silicon and a source of magnesium in a concentration of between about 10 and about 80 mg magnesium per liter of feed water, to produce treated water and a magnesium precipitate containing fluorine and separating the precipitate from said treated water such that the treated water contains loss than about 0.9 mg/L fluoride ions, wherein the magnesium precipitate comprises 3MgO.Mg(OH)2.6SiO2.6H2O (sepiolite), and Mg(OH)2 (magnesium hydroxide).

A process for reducing boron content of water, the process comprising contacting feed water containing boron in the presence of a source of magnesium and a source of silicon with an alkaline hydroxide to adjust the pH of the feedwator to at least about 10.2 to produce treated waler and a magnesium precipitate comprising an alkaline magnesium silicate and boron and separating the precipitate from said treated water such that the treated water has a reduced boron content, wherein the magnesium precipitate is 3MgO.Mg(OH)2.6SiO2.6H2O (sepiolite), and Mq (OH)2 (magnesium hydroxide).

A process for reducing fluoride ion content of water, the process comprising contacting feed water containing fluoride ion in the presence of a source of magnesium and a source of silicon with an alkaline hydroxide to adjust the pH of the feedwater to at least about 10.2 to produce treated water and a magnesium precipitate comprising an alkaline magnesium silicate and fluorine and separating the precipitate from said treated water such that the treated water has a reduced fluoride ion content, wherein the magnesium precipitate comprises 3MgO.Mg(OH)2.6SiO2.6H2O (sepiolite) and Mg(OH)2 (magnesium hydroxide).

A process for reducing boron content of water, the process comprising contacting feed water at a temperature in the range of about 85° F. to about 130° F. containing boron in the presence of silicon and a source of magnesium with an alkaline hydroxide to adjust the pH of the feed water to between about 10.2 and about 10.6 to produce treated water and a magnesium precipitate containing boron, and separating the precipitate from said treated water to produce treated water having a reduced boron content, wherein the magnesium precipitate comprises 3MgO.Mg(OH)2.6SiO2.6H2O (sepiolite), and Mg (OH)2 (magnesium hydroxide).

A process for reducing fluoride ion content of water, the process comprising contacting feed water at a temperature in the range of about 85° F. to about 130° F. containing fluoride ion in the presence of silicon and a source of magnesium in a concentration of between about 10 and about 80 mg magnesium per liter of feed water with an alkaline hydroxide to adjust the pH of the feed water to between about 10.2 and about 10.6 to produce treated water and a magnesium precipitate containing fluorine, and separating the precipitate from said treated water to produce treated water having a reduced fluoride ion content, wherein the magnesium precipitate is 3MgO.Mg(OH2.6SiO2.6H2O (sepiolite), and Mg(OH)2 (magnesium hydroxide).