GB2320247A

GB2320247A - Treating materials, especially medical wastes

Info

Publication number: GB2320247A
Application number: GB9726223A
Authority: GB
Inventors: Brian Conrath Langenegger
Original assignee: Eskom
Current assignee: Eskom
Priority date: 1996-12-13
Filing date: 1997-12-11
Publication date: 1998-06-17
Also published as: CA2224629A1; GB9726223D0; FR2757063A1

Abstract

Equipment 10 for treating materials comprises a loading bin 12. A shredder 18 is arranged at an outlet 20 of the loading bin 12. A housing 28 is arranged downstream of the shredder 18. A heat source 34 is provided for heating the chamber of the housing 28 to treat comminuted materials contained in the housing 28. In particular, the material is medical waste and the heat source is a microwave source comprising a magnetron 36 which feeds microwaves through transparent panel 40. Exterior wall 42 may be wrapped in a heating tape (78, Fig.2).

Description

THIS INVENTION relates to the treatment of materials. More particularly, the invention relates to a method of, and equipment for, treating materials.

According to a first aspect of the invention, there is provided a method of treating materials, the method including the steps of: comminuting the materials to be treated; wetting the materials; introducing the wet, comminuted materials into a chamber; and heating the interior of the chamber to effect treatment of the materials in the chamber.

The invention has particular application in the treatment of infectious medical wastes and, more particularly, the steriiisation of such waste material.

Accordingly, the invention will be described with reference to that application hereafter. The invention is intended specifically, but not necessarily exclusively, for the treatment of what is known as "soft" medical waste although, should other types of medical waste be included with the soft medical waste, the equipment is able to treat such medical waste as well.

Normally, the waste to be sterilised is placed in a container such as a bag. Thus, the method may include, initially, bagging the materials prior to comminuting the materials.

The method may also include wetting the materials with heated water.

If desired, the method may include dosing the materials with a dosing agent prior to the introduction of the materials into the chamber. The dosing agent may be introduced into the heated water.

Preferably, the method includes treating the materials by irradiating the materials. In particular, the method may include irradiating the materials with microwaves to effect generation of a vapour to sterilize the materials in the chamber.

The method may include, in addition, heating a wall of the chamber to effect treatment of the materials in the chamber.

After heat treatment of the materials in the chamber, the method may include venting the vapour from the chamber prior to discharge of the treated materials from the chamber.

The method may include agitating the materials in the chamber during the treatment of the materials.

According to a second aspect of the invention, there is provided equipment for treating materials, the equipment including a comminuting means for comminuting the materials to be treated; a chamber defining means arranged downstream of the comminuting means so that comminuted materials are discharged into a chamber of the chamber defining means; and a heating means for heating an interior of the chamber and its contents to effect treatment of the materials.

Preferably, the equipment includes a source of a wetting agent for wetting the materials.

The equipment may include a receptacle having a loading opening into which the bagged waste materials are received for treatment. A closure means may be provided for closing the loading opening with a monitoring means for monitoring a position of the closure means. The monitoring means may be an interlock for monitoring the condition of the closure means and for disabling the equipment when the closure means is open.

The equipment may include a negative pressure generating means, in the form of an extraction fan, for generating a negative pressure in an interior of the receptacle.

The source of wetting agent may comprise a water supply means for effecting wetting of the materials, the supply means including a heating means for pre-heating the water prior to introducing the water into the receptacle. The water may be introduced into the equipment via the loading bin together with the waste material. If desired, a dosing agent may be introduced into the water supply for aiding in the sterilisation of the waste material.

The comminuting means may comprise a shredder. A first isolation device may be arranged intermediate an outlet from the shredder and an inlet to the chamber defining means and a second isolation device may be arranged at an outlet from the chamber defining means. The first isolation device and the second isolation device may both be in the form of isolation valves.

The heating means may include a microwave system. The microwave system may comprise a microwave power supply for generating microwaves and a waveguide for feeding the microwaves from the power supply to the chamber.

An outlet of the waveguide, terminating in a wall of the chamber defining means, may be closed off by a panel which is transparent to the microwaves to inhibit contamination of the microwave system by the contents of the chamber.

The heating means may, additionally, include a heating element, in the form of a heating tape, carried on an external surface of the chamber defining means. Further, an insulating layer may be placed about the external surface of the housing.

Material sterilized within the housing, after discharge through the outlet of the housing, may be disposed of directly or may, if desired, first be dried prior to disposal.

The invention is now described by way of example with reference to the accompanying diagrammatic drawings.

In the drawings, Figure 1 shows a schematic, three dimensional view of equipment, in accordance with a first embodiment of the invention, for treating materials; and Figure 2 shows a schematic side view of a second embodiment of the equipment.

In Figure 1 of the drawings, reference numeral 10 generally designates equipment, in accordance with the invention, for treating materials. As indicated above, the equipment 10 is intended particularly for use in the sterilisation of infectious medical waste material, more particularly, soft medical waste.

The equipment 10 comprises a loading means in the form of a loading bin 1 2. The loading bin 1 2 has an access opening 1 4 defined in it which is closed off by a door 1 6. A comminuting means in the form of a shredder 1 8 is arranged at an outlet 20 of the loading bin 1 2.

The equipment 10 includes a water supply tank 22 including a pre heater 23 for pre-heating the water. Water from the tank 22 is supplied via a conduit 24 and nozzies, as illustrated schematically at 26, into the interior of the loading bin 1 2.

A chamber defining means in the form of a spherical housing 28 is arranged downstream of the shredder 1 8 and is connected to the shredder 1 8 via an isolation device in the form of an isolation valve 30. The housing 28 defines a chamber 32 in which medical waste material to be sterilized is received, as will be described in greater detail below.

The equipment 10 includes a heat source 34 for heating the chamber 32 of the housing 28. The heat source 34 is a microwave heat source and comprises a magnetron 36 which feeds microwaves via a waveguide 38 into the chamber 32 through a panel or window 40 which is transparent to the microwaves. The window 40 is defined in a wall 42 of the housing 28 and is provided to inhibit contamination of the microwave heat source 34.

The magnetron 36 is a 1.2 kW to 2 kW magnetron operable at a frequency of 2450 MHz. It will be appreciated that the size of the magnetron 36 will be dependent on the volume of the chamber 32 of the housing 28. Typically, the chamber has a diameter in the region of approximately 450 to 500 mm and, preferably, about 480 mm. The spherical housing 28 permits numerous modes of propagation of the microwaves in the chamber 32 thereby to improve the sterilisation capabilities of the equipment 10.

The equipment 10 includes an agitating device 44 arranged in the chamber 32. The agitating device 44 comprises a stirrer or wiper 46 mounted on a shaft 48. The shaft 48 is rotatably mounted in the chamber 32, ends 48.1 of the shaft 48 being supported in the wall 42 of the housing 28 via choked bearings 50. One end of the shaft 48 is connected to a motor 52 which drives the shaft 48 and, hence, the wiper 46 rotatably. It is to be noted that the wiper 46 is arcuate having approximately the same radius of curvature as the wall 42 of the housing 28 to sweep an interior surface of the wall 42 of the housing 28.

To assist in the heating of the contents of the chamber 32, an exterior surface of the wall 42 of the housing 28 is wrapped in a heating tape (as illustrated schematically at 78 in Figure 2 of the drawings) which operates at a temperature of approximately 60 C. An insulating tape (not shown) is wrapped around the heating tape.

The housing 28 has an outlet 54 which is closed by an isolation valve 56. Further, a vent 58 is defined in the wall 42 of the housing 28.

Referring now to Figure 2 of the drawings, a second embodiment of the equipment is illustrated. With reference to Figure 1 of the drawings, like reference numerals refer to like parts, unless otherwise specified.

In this embodiment of the invention, the loading bin 1 2 is arranged upstream of a feed chute 62 arranged intermediate the loading bin 1 2 and the shredder 1 8. Thus, the feed chute 62 defines the outlet 20 feeding into the shredder 1 8. An extraction fan 64 is located intermediate the loading bin 1 2 and the feed chute 62 to create a negative pressure in the loading bin 1 2 so that, when the door 1 6 is opened, the emission of potentially harmful matter is inhibited.

Loaded bags received in the bin 1 2 are transferred to the feed chute via a fluid operable charging ram 66. The ram 66 is, preferably, pneumatically operable.

In this embodiment of the invention the chamber defining means is in the form of a right circular cylindrical housing 68 which defines the chamber 32.

The housing 68 also permits numerous modes of propagation of the microwaves in the chamber 32 for sterilization of the materials in the chamber.

Further, in this embodiment, the agitating device 44 comprises a high frequency stirrer 70 which operates in an ultrasound mode to impart vibrations to the housing 68. For inhibiting the vibrations adversely affecting the magnetron 36, the panel or window 40 also acts as a vibration isolator.

The housing 68 is mounted on a discharge trolley 74. After completion of the sterilization process, the treated materials are discharged through the isolation valve 56 into the discharge trolley 74 from where the materials can be removed for disposal. As illustrated, the trolley 74 is mounted on wheels 76 for rendering the equipment 10 portable.

In use, the soft-medical waste to be sterilized and disposed of is placed in bags. These bags, known as "Red Bags" typically have a mass of approximately 4 to 7 kg and two such bags can be treated at once. The bags, carrying the medical waste, are introduced into the loading bin 1 2 via the access opening 14 and the door 16 is closed. An interlock 60 monitors the condition of the door 16 and, should it open, the equipment 10 is tripped to become inoperative.

Pre-heated water from the tank 22 is fed through the conduit 24 via the nozzles 26 into the interior of the loading bin. The bags, containing the waste material, and the water are fed into the shredder 1 8 where the bags and their contents are shredded. While the shredder 1 8 is operative, the isolation valve 30 remains closed. The shredder 1 8 shreds the waste material to the required size and the waste material is mixed with the water.

Upon completion of shredding, the isolation valve 30 opens discharging the wet, shredded material from the shredder 1 8 into the chamber 32 of the housing 28, 68. Thereafter, the isolation valve 30 closes. It will be appreciated that, during this time, the isolation valve 56 at the outlet 54 of the housing 28, 68 is a!so closed. The chamber 32 is pressurized to a pressure of approximately 2 bar by activating the microwave heat source 34 to cause an increase in temperature in the chamber 32. The operation of the microwave heat source 34 is controlled by a pressure monitoring device which monitors the pressure of the chamber 32. At a pressure of 2 bar, the interior of the chamber is heated to a temperature of approximately 120"C under the control of the pressure monitoring device. The chamber 32, with its contents is maintained at this pressure and temperature for a predetermined period of time, typically about 40 minutes. During this time, the water contained in the waste material is converted to steam which effects the sterilisation of the shredded, waste material.

Upon completion of the sterilisation process, the steam is vented to atmosphere through the vent 58. The remaining material is then discharged from the chamber 32 of the housing 28 through the outlet 54 by opening the isolation valve 56. The material discharged from the housing 28 can either be disposed of directly, for example, into a sewerage system or may be fed to a drying station (not shown) for drying and subsequent disposal.

In the sterilisation of the waste material, a chemical dosing agent may be introduced into the equipment 10 with the water from the water tank 22, via a conduit 72. This dosing agent may, for example, be a peroxide-based material.

The size of the equipment 10 renders it semi-portable and enables it to be used in a point-of-use application. Thus, typically, a number of the items of equipment 10 are placed at strategic locations in a medical institution where the medical waste can be sterilised. This is beneficial in that the medical waste does not have to be transported long distances and handled by a number of people.

Also, by shredding the waste, prior to sterilising it, the volume of the waste can be reduced by up to 80%. Further, the waste is transformed into an unrecognisable form and much of the surface of the waste material is exposed for sterilisation purposes.

In addition, due to the fact that the equipment 10 is semi-portable, the waste material can effectively be sterilised almost as soon as it is generated and the problems associated with storage of the waste material are alleviated.

Claims

1. A method of treating materials, the method including the steps of: comminuting the materials to be treated; wetting the materials; introducing the wet, comminuted materials into a chamber; and heating the interior of the chamber to effect treatment of the materials in the chamber.

2. The method as claimed in Claim 1 which includes, initially, bagging the materials prior to comminuting the materials.

3. The method as claimed in Claim 1 or Claim 2 which includes wetting the materials with heated water.

4. The method as claimed in any one of the preceding claims which includes dosing the materials with a dosing agent prior to the introduction of the materials into the chamber.

5. The method as claimed in any one of the preceding claims which includes treating the materials by irradiating the materials.

6. The method as claimed in Claim 5 which includes irradiating the materials with microwaves to effect generation of a vapour to sterilize the materials in the chamber.

7. The method as claimed in Claim 6 which includes, in addition, heating a wall of the chamber to effect treatment of the materials in the chamber.

8. The method as claimed in Claim 7 which includes venting the vapour from the chamber prior to discharge of the treated materials from the chamber.

9. The method as claimed in any one of the preceding claims which includes agitating the materials in the chamber during the treatment of the materials.

1 0. Equipment for treating materials, the equipment including a comminuting means for comminuting the materials to be treated; a chamber defining means arranged downstream of the comminuting means so that comminuted materials are discharged into a chamber of the chamber defining means; and a heating means for heating an interior of the chamber and its contents to effect treatment of the materials.

11. The equipment as claimed in Claim 10 which includes a source of a wetting agent for wetting the materials.

1 2. The equipment as claimed in Claim 11 which includes a receptacle having a loading opening into which the materials are received for treatment.

1 3. The equipment as claimed in Claim 1 2 which includes a closure means for closing the loading opening and a monitoring means for monitoring a position of the closure means.

14. The equipment as claimed in Claim 1 2 or Claim 1 3 which includes a negative pressure generating means for generating a negative pressure in an interior of the receptacle.

15. The equipment as claimed in any one of Claims 11 to 14 inclusive in which the source of wetting agent comprises a water supply means for effecting wetting of the materials, the supply means including a heating means for preheating the water prior to introducing the water into the receptacle.

1 6. The equipment as claimed in any one of Claims 10 to 1 5 inclusive in which the comminuting means comprises a shredder.

1 7. The equipment as claimed in Claim 1 6 in which a first isolation device is arranged intermediate an outlet from the shredder and an inlet to the chamber defining means and a second isolation device is arranged at an outlet from the chamber defining means.

1 8. The equipment as claimed in any one of Claims 10 to 1 7 inclusive in which the heating means includes a microwave system.

1 9. The equipment as claimed in Claim 1 8 in which the microwave system comprises a microwave power supply for generating microwaves and a waveguide for feeding the microwaves from the power supply to the chamber.

20. The equipment as claimed in Claim 1 9 in which an outlet of the waveguide, terminating in a wall of the chamber defining means, is closed off by a panel which is transparent to the microwaves.

21. The equipment as claimed in any one of Claims 1 8 to 20 inclusive in which the heating means, additionally, includes a heating element carried on an external surface of the chamber defining means.

22. The equipment as claimed in any one of Claims 10 to 21 inclusive in which an agitating means is mounted on the chamber defining means for agitating the contents of the chamber defining means during heating of the materials.

23. A novel method of treating materials substantially as described herein.

24. New equipment for treating materials substantially as described herein with reference to the accompanying diagrammatic drawings.