METHOD OF SOFTENING WATER Russian patent published in 1998 - IPC

FIELD: drinking water treatment. SUBSTANCE: calcium hydroxide, potassium carbonate, and potassium hydroxide are consecutively added to water, potassium carbonate quantity being determined from equation 48-53h where h is constant hardness of water and quantity of potassium hydroxide not exceeding 50 mg/l. Once precipitate separated, water is treated by food acid until pH ≤ 8 is attained. Instead of potassium carbonate, soluble part of sunflower ashes can be used with 15% K₂CO₃, 3.3% KCl, and 1.7% K₂SO₄, or soluble part of slop coal and ashes with their solid part containing 81-96% K₂CO₃, 0.5-2.5% K₂SO₄, 1.0-6.4% KCl, and 0.5-10.0% Na₂CO₃. Before adding salts, water is warmed to 35-50 C and, with all salts added, treated in alternate electric field. EFFECT: improved quality of water. 5 cl, 2 tbl