Patent GB-384466-A (GB)
Title: Improvements in and relating to the sterilisation of liquids
IPC: B43M11/08
Filed: 1932-01-25
Abstract: 384,466. Electrolytic sterilization of liquids. KRAUSE, G. A., 16, Widenmayerstrasse, Munich, Germany. Jan. 25, 1932, No. 2239. Convention date, Jan. 29, 1931. [Class 41.] Liquids such as milk, fruit juices, vegetable extracts, sera, waste waters, and particularly drinking water are oligodynamically sterilized by supplying the active metal to the liquid from electrodes of which the anode only or both are of the active metal, e.g. silver or copper, the quantity of liquid and the electric current conditions being controlled relatively to each other to bring a definite quantity of the metal into the active state. The amount of metal brought into the liquid is very small, e.g. in the case of drinking water it may be 0.1 mg. of silver per litre, and the current employed is correspondingly small, e.g. in treating the water 0.2 ampere seconds, the currents used being too low to produce electrolytic action other than the solution of the small amount of active metal required. The electrodes may be plates or may be permeable, e.g. of separate pieces such as rods, chips, and strips, or of metal-coated bodies filled into perforated containers of porcelain or other non- conducting or conducting material which are suspended in the liquid. Means may be provided for replenishing the anode, e.g. by feeding into the liquid at the rate at which it is consumed. Means are described for keeping the anode free from deposits and preventing turbidity of the liquid by formation of suspensions. The cathode may be of the same metal as the anode and the direction of the current may be reversed to remove deposit from the anode, or the anode may be cleaned mechanically by brushing or grinding off the deposit or by washing it off with the liquid being treated or another liquid, e.g. by agitating the liquid near the anode or by squirting on liquid under pressure. The formation of an anode crust and of turbidity may be prevented by surrounding the anode 13, Fig. 3, with a diaphragm 25, e.g. a porous earthenware cylinder, into which are introduced chemicals from a vessel 27, to dissolve the crust, e.g. in the case of silver, ammonia is introduced. Where the liquid is passed continuously through the treatment chamber 11, Fig. 2, between the electrodes 13, 14 it may subsequently be passed through a filter 20. In another form, the electrodes 32, 33, Fig. 4, are formed as filters, the liquid being forced through the treatment chamber 31 by a pump 30. The cleaning of the filters may be effected by reversing the direction of the current. A portion of the liquid may be treated so that a greater quantity of active metal than normal is brought into it, and the liquid is then added to untreated or weakly treated liquid, the correct concentration being thus obtained and suspensions in the treated liquid being dissolved. The liquid may be heated prior to, during or after the oligodynamic treatment. The liquid may be connected to earth when flowing through the treatment chamber. A number of treatment chambers may be employed, connected in series or in parallel.