WO1999064076A1

WO1999064076A1 - Process and apparatus for the disinfection of medical waste

Info

Publication number: WO1999064076A1
Application number: PCT/IB1999/001053
Authority: WO
Inventors: Bruno Aubert
Original assignee: Bruno Aubert
Priority date: 1998-06-08
Filing date: 1999-06-08
Publication date: 1999-12-16
Also published as: AU4053399A; FR2779350A1; FR2779350B1

Abstract

There is provided a method and container suitable for use in disinfecting waste, the method comprising the steps of supplying a container having an access opening therein, at least a portion of the container being formed of a heat shape memory material which is in a deformed state, the container having an access opening with a valve structure and filter therein, the method including the step of heating the container to a temperature sufficient to cause the container to return to an undeformed state thereby compacting the waste in the container and desinfecting the waste. The container is economical to manufacture and may be used for the desinfection of relatively small amounts of waste.

Description

PROCESS AND APPARATUS FOR THE DISINFECTION OF MEDICAL WASTE

The present invention relates to a process for disinfecting waste and in

particular medical waste and a container suitable for practice of the method.

BACKGROUND OF THE INVENTION

There are many known methods and devices which have been proposed for the

disinfection of waste and in particular, waste carrying biological risk such as medical

waste. These wastes can be generated in both large and small quantities from

organizations as large as hospitals to extremely small amounts of waste such as may

be generated by an individual medical practitioner or small laboratory. The waste can

include swabs, needles, plastic containers, etc. which are used in medical treatments.

One means of disinfecting medical waste is by collecting the same for

subsequent treatment such as in an incinerator or in a large installation for thermal

treatment - such treatments may include super heated steam, high frequency

microwave, etc. One disadvantage of this arrangement is that multiple handling of the

waste during the various steps is required - i.e. the grinding, sorting, etc. Also, the

waste is subjected to an intermediate storage for one or more days which can cause an

unacceptable proliferation of pathogenic germs and contamination risks all along the

treatment chain - i.e. the trash can, grinder, transport vehicle, etc.

It is also known to treat the medical waste in situ in order to eliminate the

proliferation problem during the intermediate storage. Machines using jets of ozone or

disinfectant solutions have been proposed. However, they suffer from the

disadvantage that they can not disinfect closed objects such as needles used to take

blood samples and the like, into which the disinfecting agents do not enter. Thermal means for treating waste are also known, and are beginning to gain

wider acceptance in the industry. Generally, they require the grinding of waste for

better thermal transfer of heat from either overheated steam or of a high frequency

source of waves. Normally, such machines are used for relatively large capacities

(20 kg to 250 kg per hour) and they represent a substantial investment as they require

large spaces which frequently leads to placing them far from the waste generating site.

This again brings up the problem of storage and transportation and the proliferation of

the pathogenic germs.

Recently, there have been proposed a method and device for thermally

disinfecting relatively small sources of waste, one such device being shown in

WO Application PCT/FR97/0258 dated February 9, 1997. Although this device does

overcome the problem of treating somewhat smaller portions of medical waste, it still

does not represent an economically viable solution for the extremely small waste

generator. In particular, this invention is concerned with units which would generate

between 1 kg to 5 kg of waste per month, such as may be the case encountered in

individual medical offices and/or in small laboratories. Currently, such waste

generators must continue to pay for the transport of the medical waste to an

installation wherein there is a larger piece of equipment designed to dispose of the

medical waste.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method and apparatus

suitable for the treatment of small amounts of medical waste and which method and apparatus will reduce the possibility of the proliferation of pathogenic germs and do so

at an economical cost.

According to one aspect of the present invention, there is provided a method of

disinfecting waste comprising the steps of supplying a container having an access

opening therein, the container being at least partially formed of a heat shape memory

material, the heat shape memory material being in a deformed state; placing the waste

in the container through the access opening; covering the opening with a valve

structure having a filter therein; and heating the container to a temperature sufficient

to cause the container to return to an undeformed state thereby compacting the waste

in the container, the temperature being sufficiently high to disinfect the waste.

In a further aspect of the present invention, there is provided a container

suitable for use in disinfecting waste, the container comprising a body portion at least

partially formed of a heat shape memory material, the heat shape memory material

being in a deformed state, a cavity within the body portion, an access opening in the

body portion communicating with the cavity, and a cover member for covering the

access opening, the cover member comprising a valve arrangement having a filter

member therein.

As set forth above, there is provided a container which is formed of a material

having a heat shape memory (referred to herein as a heat shape memory material) and

which material is in a deformed state. Such materials having a heat shape memory are

known in the art and may be either of an organic or metallic nature. A container made

of such a material can be deformed from an original heat stable configuration to a second heat unstable configuration. The article is said to have shape memory for the

reason that, upon the application of heat, the material can be caused to revert from its

heat unstable condition to its original heat stable configuration - i.e. it remembers its

original shape.

Generally, among metallic alloys, the ability to possess shape memory is a

result of the fact that the alloy undergoes a reversible transformation from an

austenitic state to a martensitic state with a change in temperature. This

transformation has been referred to as a thermoelastic martensitic transformation.

A container made from such an alloy may be deformed from its original configuration

to a new configuration when it is below the temperature at which the alloy is

transformed from the austenitic state to the martensitic state. When the container thus

formed is heated to a temperature at which the alloy starts to revert back to austenite,

the deformed object will begin to return to its original configuration.

Various alloys have been proposed in the art including nickel/titanium alloys,

gold/cadmium alloys, silver/cadmium alloys, copper/zinc alloys, copper/aluminum

alloys and iron based alloys including iron/nickel, on/nickel/chromium and certain

stainless steels.

According to the present invention, the container may be formed in any desired

configuration and has an internal cavity for receiving the waste material to be

disinfected. Thus, such containers may be of any conventional configuration

including rectangular, circular, etc. The container includes an opening or aperture into

the body for purposes of placing the waste material to be disposed of therein. If desired, only a portion of the container could be formed of the heat shape memory

material.

When sufficient waste is received, a cover structure is placed over the opening

and the container is heated.

The means of heating the container may again comprise any suitable with a

preferred method being one of convection heating such as in an oven. Alternatively,

the container could be subjected to electrical resistance heating, including using the

container itself as the electrical conductor.

The container is heated to a temperature sufficient both to disinfect the waste

therein and to cause the heat shape memory material to revert back to its original

undeformed state. For purposes of disinfection, temperatures between 121°C and

250°C are preferred and accordingly, one could select a suitable alloy material which

will also undergo a transformation back to austenite within the same temperature

range. It is naturally within the skill of those knowledgeable in the art to choose a

suitable material having heat shape memory which will transform at the desired

temperature.

As the material reverts back to its undeformed shape, the waste material within

the container will tend to be compacted thus further increasing the thermal transfer

efficiency due to a higher density and thus assure the disinfection of the material

therein. The temperature is continued for a period of time sufficient for the waste

material to be disinfected. The cover includes a filter and a gate/valve arrangement, the filter being one to

prevent the release of foul smelling odors and also to ensure the efficiency thereof.

The filter is preferably of a very high efficiency (99.999%) to remove all particles

down to a size of 0.01 μm. A mineral membrane or stainless steel fibers or active

carbon and/or Teflon™ felt may be used. The gate or valve will permit the

maintenance of the desired vapor pressure within the container as is well known.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus generally described the invention, reference will be made to the

accompanying drawings illustrating an embodiment thereof, in which:

Figure 1 is a schematic side sectional view of a container according to the

present invention; and

Figure 2 is a schematic side elevational view showing the container after

heating.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in greater detail and by reference characters thereto,

there is shown in Figure 1 a container generally designated by reference numeral 10

and which includes a base 12 and a side wall 14. Side wall 14 is formed of a heat

shape memory material and has been deformed to have a somewhat pleated or

accordion type side wall.

At the top, contamer 10 is provided with an access opening 16 having a cover

18. Mounted within cover 18 there is provided a high efficiency filter 20 and a gate or

valve 22. The container, after being filled with medical waste 24, is then subjected to a

heating operation, preferably at a temperature of between 121°C to about 250°C. The

heat shape memory material forming side wall 14 will then revert to the compacted

shape shown in Figure 2. The waste material will similarly be compacted to a far

greater density than the original thus aiding in the thermal disinfection of the waste.

The valve arrangement 22 is preferably rated at between 3 - 5 bars to maintain

a sufficient vapor pressure within the container. It is only after being heated that any

material will be permitted to pass through valve 22 and filter 20 which, as previously

mentioned, is a high efficiency filter.

Claims

I CLAIM:

1. A method of disinfecting waste comprising the steps of:

supplying a container (10) having an access opening (16) therein, said container

being at least partially formed of a heat shape memory material, said heat shape

memory material being in a deformed state;

placing said waste (22) in said container (10) through said access opening (16);

covering said opening (16) with a valve structure (20) having a filter (18)

therein; and

heating said container to a temperature sufficient to cause said container to

return to an undeformed state thereby compacting said waste in said container, said

temperature being sufficiently high to disinfect said waste.

2. The method of Claim 1 wherein said container is heated to a temperature of

between 121┬░C and 250┬░C.

3. The method of Claim 2 wherein the step of heating said container comprises

the step of placing said container in an oven and heating said oven.

4. The method of Claim 2 wherein said heat shape memory material is a metallic

alloy and is heated by electric resistence heating passing through said container.

5. The method of Claim 4 wherein said container is initially placed in a second

container prior to said heating.

6. The method of Claim 2 wherein said valve has a high efficiency filter to

remove particles having a size greater than 0.01 ╬╝m.

7. The method of Claim 2 wherein said container has an original volume before

heating of between 0.5 liters to 3 liters.

8. The method of Claim 2 wherein said heat shape memory material is a metallic

alloy.

9. The method of Claim 1 wherein the step of heating said container comprises

the step of heating said container to a temperature of between 140┬░C to 150┬░C.

10. A container suitable for use in disinfecting waste, said container (10)

comprising a body portion at least partially formed of a heat shape memory material,

said heat shape memory material being in a deformed state, a cavity within said body

portion, an access opening (16) in said body portion communicating with said cavity,

and a cover member for covering said access opening, said cover member comprising

a valve arrangement (20) having a filter member (18) therein.

11. The container of Claim 10 wherein said heat shape memory material is a

metallic alloy.

12 The container of Claim 11 wherein said filter member is a high efficiency filter

to remove all particles having a size greater than 0.01 ╬╝m.