Water softening process.

摘要

Process and apparatus for softening hard water by precipitation of calcium carbonate. The hard water is rendered alkaline, e.g. by the addition of sodium hydroxide, and is then contacted with a large excess of calcium carbonate crystals whose size does not exceed 100 microns, whereby precipitation occurs within a short contact time of the order of 2-60 seconds. Upon separation of soft water from calcium carbonate the bulk of the latter is recirculated and excessive amounts are removed. <IMAGE>