GB353409A - Improvements in and relating to the sterilisation of liquids - Google Patents

Abstract

353,409. Purifying liquids. KRAUSE, G. A., 9, Bavariaring, Munich, Germany. Feb. 21, 1930, No. 5882. Convention date, March 1, 1929. [Class 46.] Liquids, especially water, are sterilized by adding thereto salts of oligodynamically active metals in small amount, not exceeding 2 mgms. of metal per litre, and leaving the liquid for sufficient time after the mixing to allow the sterilization to be completed before drawing it off for use. The time for which the liquid is held is longer as the amount of the salt added is decreased. Salts of silver, copper or mercury may be used. The metal may be removed and recovered from the treated liquid, e.g. by deposition on a grid or filter of a baser metal such as iron or aluminium, a corresponding amount of which goes into solution, or by absorption, or electrochemical means. Where water is sterilized and is then treated with lime, the presence of salts of iron and aluminium, when added by the metal-recovery step, will be of use in the coagulation process. The apparatus used in sterilizing must not contain a metal baser but may contain one the same as or nobler than that in the sterilizing salt. The apparatus may be constructed of glass, stoneware or other non-metallic material. The treatment may be combined with oligodynamic sterilization by the aid of a free metal which must not be less noble than that in the salt added. In the example given, water, which may have been filtered, flows in through a pipe a to a vessel d where a solution of the sterilizing salt, such as silver nitrate or copper sulphate, of known strength prepared in a vessel b is added in accurately measured quantity through a pipe c. The water then enters chamber f through which it takes three hours to flow, the chamber being subdivided by partitions or by fillers which may be coated with a suitable metal to increase the sterilizing action. The sterilized water passes to a vessel i which contains a grid or filter k formed of iron wire netting or iron clippings or turnings. The purified water leaving at l may be further treated with lime and filtered. The sterilizing salt may alternatively be added in solid form. Specification 325,796, [Class 46, Filtering &c.], is referred to.