METHOD FOR STERILIZING SOLID REFUSE BY ACTIVE CHLORINE RELEASED BY THE REACTION OF HALAZONE WITH WATER

Abstract: A method for disinfecting solid refuse contained in bags by the action of chlorine released from solid mixtures containing halazone, implemented by the following stages: a) bringing the solid mixture containing halazone into contact with an alkaline solution in a suitable reaction container; b) immediately introducing said container into the bag; c) closing the bag to allow the chlorine released in the gaseous state by the reaction to exercise its disinfectant action. The invention also relates to said reaction container, which has the characteristic of confining the aqueous suspension in such a manner as to prevent it escaping whatever its position.

Description: Field of the invention This invention relates to a method for disinfecting solid refuse contained in bags by chlorine which is released in the gaseous state by the reaction of halazone with an alkaline solution, and to the relative container. Prior Art Halazone and mixtures containing it are known for their use in disinfecting drinking water. Halazone, or 4-(dichlorosulphamoyl) benzoic acid, decomposes on contact with water to produce hypochlorous acid, which exerts its known bactericide action in the water by releasing active chlorine. Halazone is however poorly soluble in water but it is well known that its solubility can be increased by mixing it with an alkaline substance such as sodium carbonate, which salifies the carboxyl function. Disinfection is also required for solid refuse originating from hospitals, biological laboratories and the like, which has to be disinfected before being burnt. This operation is currently done using disinfectant liquids, which have drawbacks both from the operational viewpoint in that they are hardly practical, and also from the result viewpoint in that they are inefficient, because it is impossible to distribute the liquid uniformly throughout the solid refuse mass. Summary of the invention This invention relates to a method for disinfecting solid refuse contained in bags by the action of chlorine released from solid mixtures containing halazone, characterised by: a) bringing the solid mixture containing halazone into contact with an alkaline solution in a suitable reaction container which confines the aqueous suspension in such a manner as to prevent it escaping whatever its position; b) immediately introducing said container into the bag in any position; c) closing the bag to allow the chlorine released in the gaseous state by the reaction to exercise its disinfectant action. The invention also relates to said reaction container, which is characterised by being provided with a tube which extends inwardly as a continuation of the neck portion in order to prevent escape of liquid whatever the position it assumes within the bag. Detailed description of the invention The method of the present invention is based on the following reaction between halazone and water: The hypochlorous acid then decomposes to release "active" chlorine which exercises its known bactericide action. The expression "active chlorine content of a substance" conventionally means the quantity of molecular chlorine equivalent to the theoretically evolved hypochlorous acid. As one mole of halazone releases two moles of hypochlorous acid, its active chlorine content is 52%, this value being double the chlorine present in the molecule. For the method according to the invention, a solid mixture of halazone and sodium carbonate is used having an active chlorine content of between 15 and 25% by weight and a sodium carbonate content of between 50 and 70% by weight. This mixture is used in powder form. To release the active chlorine this mixture is brought into contact with an alkaline solution having a pH of between 11 and 13. The weight ratio of the alkaline solution to the active chlorine contained in the solid mixture is between 15 and 25. The contact between said solid mixture and said alkaline solution is made in the container shown in Figures 1 and 2 in which the reference numeral 1 indicates the cylindrical wall of the container, 2 indicates the cylindrical neck portion and 3 indicates a tube projecting inwards as a continuation of said neck portion and coaxial to said wall 1. Contact between said solid mixture and said water is obtained by introducing the solid mixture into the illustrated container containing the alkaline solution. By comparing Figure 1 with Figure 2 it can be seen that with this type of container the liquid can never escape whatever the position assumed by the container, be this vertical, inverted or inclined, whereas the produced gas escapes through the neck portion. When said solid mixture and said solution are in mutual contact the container is introduced into the bag containing the solid refuse to be disinfected, and the bag is closed. The released chlorine diffuses through the refuse to produce very efficient disinfecting. Thus the method and container according to the present invention allow solid refuse to be disinfected in a manner which obviates the drawbacks of the known art by virtue of its practicality, its reliability and its efficiency. The invention is particularly suitable for application to disinfecting solid refuse from hospitals, biological laboratories and the like. The following procedure was carried out to demonstrate the effectiveness of the treatment. Portions of clean or medicated gauze were superinfected by the operator with strains of bacteria and mycetes either from collections or isolated from patients, and were placed in three different positions, i.e.at the top, in the middle and at the bottom, of special refuse bags with a useful volume of 80 litres, originating from hospital departments. A reaction container of the type show in Figure 1 containing 7.5 g of solid halazone and sodium carbonate mixture and 30 ml of alkaline solution at pH 12 was then placed in each bag. The bag was immediately closed to prevent escape of gaseous chlorine. A control was prepared in an analogous manner and immediately analyzed to evaluate the initial microbe charge. After 24 hours of contact the treated gauze portions were removed from the bag to evaluate the numerical reduction in micro-organisms compared with the control material. The results demonstrate strong activity of the chlorine gas against Gram-negative bacteria. In particular, three strains of Pseudomonas aeruginosa , multiresistant and nosocomial, and present in a quantity of 10⁹⁻10¹², were reduced to less than 10. Klebsiella pneumoniae was also reduced after treatment from 1 x 10⁹ to less than 10 in the samples arranged in the three positions within the bag. The same result was obtained for Escherichia coli , which was reduced from 1.9 x 10¹² to less than 10 in all three samples. The results were also excellent in the case of mycetes, in that Candida albicans , which was present in the control in a quantity of 1 x 10⁶, was reduced to less than 10 in the three samples. In the case of other strains which proved more resistant, such as coagulase-negative Staphylococcus , which was reduced on the average from 2 x 10¹² to 4 x 10³, it was found that by doubling the halazone quantity, i.e.the quantity of available chlorine, by inserting two containers in the bag, an almost total germ reduction was obtained in the three samples. The following examples relative to the release of the chlorine available in the halazone-sodium carbonate mixture are given by way of illustration. EXAMPLE 1 0.75 g of a 2:3 w/w halazone-sodium carbonate mixture corresponding to 0.15 g of active chlorine were placed in a 25 ml container. 3 ml of water were then added and left to react for 90 minutes at ambient temperature. The residual active chlorine was then determined, from which it was calculated that 78.2% of the active chlorine had been released. EXAMPLES 2 - 4 (comparison) Example 1 was repeated but with the difference that respectively 2, 5 and 7 ml of water were used, to obtain released active chlorine quantities of 68.5%, 66.4% and 65.2% respectively. EXAMPLE 5 Example 1 was repeated but with the difference that the water pH was adjusted to 12.8 by adding NaOH. The active chlorine released was 71.2%. EXAMPLE 6 (comparison) Example 1 was repeated but with the difference that the water pH was adjusted to 1.2 by adding HCl. The active chlorine released was 71.2%. EXAMPLES 7 - 8 (comparison) Example 1 was repated but with the difference that the water pH was adjusted to 13 and 13.5 respectively by adding NaOH. The active chlorine released was 82.3% and 79.8% respectively.

Claims: A method for disinfecting solid refuse contained in bags by the action of active chlorine released from solid mixtures containing halazone, characterised by: a) bringing the solid mixture containing halazone into contact with an alkaline solution in a suitable reaction container which confines the aqueous suspension in such a manner as to prevent it escaping whatever its position; b) immediately introducing said container into the bag in any position; c) closing the bag to allow the chlorine released in the gaseous state by the reaction to exercise its disinfectant action. A method as claimed in claim 1, characterised in that said solid mixture containing halazone consists of halazone and sodium carbonate, the active chlorine content being between 15 and 25% by weight and the sodium carbonate content being between 50 and 70 % by weight. A method as claimed in claim 1, characterised in that said solid mixture containing halazone is used in powder form. A method as claimed in claim 1, characterised in that said alkaline solution has a pH of between 11 and 13. A method as claimed in claim 1, characterised in that the weight ratio of said alkaline solution to the active chlorine contained in said solid mixture is between 15 and 25. A method as claimed in claim 1, characterised in that said reaction container is provided with a tube (3) which projects inwards as a continuation of the neck portion (2) and is coaxial to the container walls (1).

Inventors: GASPAROTTI, FRANCA ANGELA
Applicants: L. MOLTENI & C. DEI F.LLI ALITTI S.P.A
Application year: 1988
Main classification: A61L11
IPC codes: A01N59, A61L11