Patent GB-325796-A (GB)
Title: Process for the sterilisation of liquids
IPC: A61L2/238
Filed: 1928-11-21
Abstract: 325,796. Krause, G. A. Nov. 21, 1928. Sterilizing liquids. - In a process for the partial or complete sterilization of liquids e.g. water by contact with oligodynamically active substances, contact between the liquid and the active substance is interrupted prior to the complete sterilization of the liquid and is followed by a final sterilization which may be of a multistage character. The final sterilization may be effected by auto-sterilization of the liquid itself by allowing it to stand for some time. The final sterilization may, in another form, be by treatment in several stages with active substances of greater or lesser efficiency or amount or in finer or coarser division than that used in the preliminary sterilization, and the treatment may be followed by auto-sterilization. Untreated non- sterile liquid may be added to the preliminary or finally sterilized liquid, the liquid being then finally sterilized together with the preliminary sterilized liquid. In one form, Fig. 1, water or other liquid to be treated is introduced into a funnel 2 filled with oligodynamic substance 4, which may for example be silver, copper, or silver oxide, precipitated on asbestos, clay chips &c. The liquid leaves through a filter candle 3 td a container 1 where it is completely sterilized on standing for some time by auto-sterilization. In another form, Fig. 2, a container 5 is filled with Raschig rings 6 of different sizes coated by spraying with silver, iridium or other oligodynamically active material. The container 5 between the liquid inlet 7 and the outlet 8 is divided into three sections 9, 10, 11 in which larger or smaller Raschig rings or thinner or thicker metal coatings or oligodynamically active substances of greater or less activity, for example amorphous silver, e.g. flocculated silver gel, or a mixture of amorphous and crystalline silver, or crystalline silver, are employed. The crystalline silver is the more usual form of silver, e.g., that obtained in the electro-deposition of silver. In a further form, Fig. 3, the liquid enters, through an inlet 17, a vessel 12 passing first through a chamber 14 fitted with oligodynamically active substance 16, e.g., rustless steel or silver spread on suitable carriers such as bole &c., from which it passes through an overflow 19 to a chamber 15 having partitions 20 leaving through an outlet 18, the flow and the amount of the substance 16 being controlled so that the treated liquid has the required degree of sterilization. In another form, the oligodynamically active metals, e.g. silver, copper or silver-copper alloy are spread on carriers such as quartz sand and, the preliminary or final sterilizer, or both, may operate either continuously or intermittently. Quartz sand may be coated with silver by wetting with silver nitrate solution and then heating in a muffle furnace at 400‹ C. Other arrangements of preliminary and final sterilizers with or without intermediate sterilizers are described, various numbers of the preliminary and final sterilizers being employed. The active substances may be present in one or more of the chambers in graduated sub-division or in amounts which are graduated or have a graduated effect. The treatment may be influenced or controlled by agitating the liquid, e.g.. by blowing in air or other gases, as well as by adjustment of the temperature in one or all of the stages. The liquid may be treated with light or other radiation or with electric currents in any one stage, before or after the sterilization. The liquid may be filtered before or after sterilization, or between the individual sterilizing stages. The sterilization may be selectively controlled, e.g., all or part of the pathogenic germs may be removed in the preliminary sterilization and the remaining germs in the final sterilization; harmless spores may still remain alive where it is only necessary to remove the pathogenic germs.