| abstract |
A process for treating impure water includes adding magnesium hydroxide and/or ammonium hydroxide to the water. This neutralizes the impure water and reacts with dissolved metals in the water. The metals are precipitated as metal hydroxides/oxides, which are removed from the water. Thereafter barium hydroxide is added to the water. The barium hydroxide reacts with dissolved sulphates to produce barium sulphate and, when magnesium hydroxide is used, with dissolved magnesium, to produce magnesium hydroxide. Barium sulphate and, when present, magnesium hydroxide are removed from the water. When ammonium hydroxide is used, ammonia is stripped from the water. Carbon dioxide is then added to the water. The carbon dioxide reacts with dissolved calcium in the water. The calcium is precipitated as calcium carbonate, which is removed from the water. |