WO1999006076A1

WO1999006076A1 - Method and device for destruction of contaminated hospital waste

Info

Publication number: WO1999006076A1
Application number: PCT/NO1998/000229
Authority: WO
Inventors: Jan Eggen
Original assignee: GMM AVFALLSSYSTEMER AS
Current assignee: GMM AVFALLSSYSTEMER AS
Priority date: 1997-08-04
Filing date: 1998-08-03
Publication date: 1999-02-11
Anticipated expiration: 2000-02-04
Also published as: NO973591L; AU9097998A; NO973591D0; NO304969B1

Abstract

Device for destruction of contaminated hospital waste, especially single-use equipment from operating rooms, which are infected with blood and other body fluids. The device comprises a generally closed housing (100a) with an opening (102) for supply of waste, a grinding means (103) for disintegration of the waste, a means (105) for collecting the grinded waste, arranged in a collection chamber (104), a means for supply of water, and an agent for disinfection of the waste. For the disinfection there is arranged a generator or means for supply of low pressure steam, and the means (105) for collection of grinded waste is a basket with perforated sidewalls and/or bottom, arranged with means (130, 131) to move the basket (105) between a position for collection and a position for emptying, and a mechanism (106) for emptying the content of the basket into a bigger collection container (110) for disinfected waste.

Description

Method and device for destruction of contaminated hospital waste.

The invention relates to a device for destruction of contaminated waste from hospitals, particularly plastic materials from operating rooms, which are infected with blood and other body fluids, as described in the preamble of patent claim 1.

Background

Waste from operating rooms and similar at hospitals comprises mainly single-use plastic equipment, which after use will be fouled with blood and other body fluids. The waste must therefore be handled as contaminated waste because of the danger of infection. Presently the waste is collected in containers, such as plastic bags, and transported further to a suitable receiving station for contaminated waste, or external combustion plants. The staff of the hospital must usually carry plastic bags with waste through the corridors of the hospital, with the risk that the bag might break, and that blood and other body fluids will be released onto the floor and other furniture.

In an attempt to cope with this problem, there is provided, according to EP patent application 383553, a movable device for destruction of contaminated waste from hospitals and similar. The device comprises a feeding tract, a grinding means, a means for disinfection of the waste, and an extractable container for receiving and removing of grinded and disinfected waste. Disinfection of this waste is performed here, with support of an antiseptic liquid, which means chemical disinfection. Liquid and pulverized waste are collected in a common container.

The waste treatment according to this EP -publication, is indeed producing sterile waste, but in reality this only creates a new waste problem, because of the chemical disinfection agent. With present requirements for waste disposal, the waste must therefore be transmitted to a destruction plant for contaminated waste. In addition, this device provides a transportation problem, since both liquid from the waste itself and the carrier fluid from the antiseptic solution, have to be transported. US patent publication 5087420 describes a device for destruction of contaminated waste which is similar to the previous device. The waste will be grinded, and a chemical disinfection agent added, either as a liquid or as tablets. The resulting disinfected material after the treatment will be as a slurry, and according to the patent publication it is flushed down a drain. With this method, a sterile waste will be achieved, but the resulting slurry comprises comminuted plastic material and antiseptic agents which will not be accepted in the municipal drain for subsequent waste water treatment. If the sterile slurry is collected instead, the same disadvantages exist as for the waste which is treated according to the EP- publication discussed obove.

US patent publication 5425925 also describes a device for destruction of contaminated waste of the same kind. This method also comprises a physical destruction of the waste, combined with chemical and thermal disinfection. The disinfection agent is part of a solution which recirculates during use. The solid waste is drained and may be sent to a depot or similar. The disadvantage is similar to the others, i.e. the use of chemical disinfection, and the solid comminuted material will not be completely dry in the described method. The device also needs periodic maintenance, tby changing of the circulating liquid in the device. These familiar techniques offer generally technical solutions which either demand use of chemicals and/or high pressures, and relatively large units have to be trans- ported from the operating room, through corridors, to the destruction device.

Object

The main object of the invention is to provide a device for the destruction of contaminated waste from hospitals, especially operating rooms and similar, without use of high pressure and/or chemicals, and which allows reliable destruction at a place immediate to the source of the waste.

The invention

The object is fulfilled with a device according to the characteristing part of patent claim 1. Further advantageous details are described in the dependent claims.

Examples of waste which may be handled in the device according to the invention are plastic-containers and appendant tubes, valves, clamps and similar from singel-use suction devices, Petri dishes and test tubes of plastic from hospitals and laboratories, singel-use thorax-suction, with 34x40 cm dimensions, equipment from autotransfusion and heart/lung- apparatus.

The device according to the invention makes it possible to carry out easy handling of contaminated waste, from for example operating rooms, by providing a sterile solid waste which can be collected, alternatively compressed, and sent further to a common waste system which more usually handles waste from households, and liquid waste which may be sent direct to for example the municipal drain system.

The resulting liquid waste is similar to household waste water, which is not sterile, but contains no or very little solid waste. Thus the liquid waste will not create any problems concerning waste water treatment and, for example, production of soil improvement agents. Neither the solid nor the liquid waste contains environmentally problem agents such as waste from familiar devices of this kind, resulting from the chemical disinfection.

The use of steam offers several advantages. Firstly, the use of environmentally undesirable chemicals such as ClO₂ is avoided, and eases thereby both the receiving station for handling of solid/special waste and waste water treatment plants. The use of high temperature steam will besides cause a relatively fast and smooth heating of the solid waste which is to be sterilized. The water left from the washing procedure, will evaporate quickly, so that the resulting solid waste will be relatively dry. This means reduced weight for transportation and the receiving station, which is handling the solid waste. A particular advantage of the invention is that, because of the modest size and demand for pressure and temperature of the device, the destruction can be carried out close to the source, for example in the rinsing room at an operating room, and that the device also allows destruction of more waste units, and collection in a storage container without transporting contaminated waste through the corridors of the hospital, with the danger for scattering an infection.

The grinder is an important component in the device according to the invention, and should establish a reliable grinding of the waste, which presumably will be added to it. The grind should therefore be of a strong embodiment, and cardboard or paper grinders will not satisfy this object. The grinder should be a cutting device and should not, as opposed to the familiar technique mentioned in the introduction, grind the solid waste finely into a powder, avoiding solid waste being lead to the drain together with the liquid. The cutting width should be sufficient to ensure that bag shaped material is cut, to make sure that as much as possible of the blood, body fluid and other liquids from the waste are removed in the washing procedure. The degree of grinding should on the other hand be sufficient for opening the waste up, so that blood and other foreign liquids can be removed during the washing and flushing procedure.

A grid of the Mercodor ZM1 has proven to be very suited for the object. This grid has an outer dimension which is suited for smaller stationary devices according to the invention, in for example operating rooms, and has a 35 mm cutting width, providing rotating parallel knife blades which are mounted on an axle. Between each knife blade, there are fixed stator vanes, and the distance between a knife blade and a neighbouring stator vane, is minimal in order to avoid, for example, plastic bags being drawn through the grinder and getting torn. A preferred rotation speed for a grinder of this type is 20-50 rpm and the required power is achieved with, for example, an electric motor at 3-6 kW.

The invention is illustrated in the drawings, wherein Fig. 1 shows the device according to the invention in perspective, Fig. 2 shows a schematic part section elevation view of the device according to the invention, and

Fig. 3 shows a schematic part section plan view of the device according to the invention.

The construction of the device.

The device comprises a housing 100a, and an inner housing accommodated inside the former. The inner housing is equipped with a vibration dampening means, for example, rubber bricks or similar, in order to reduce noise and vibration during operation of the grinder. The outer housing 100a is equipped with an opening 102 for supply of waste to an inlet chamber (101), with capacity of, for example, 10 litres, and an opening 106 for removal of treated solid waste which is collected in a basket as described below. In the upper part of the inner housing, a grinder 103 is arranged which ensures grinding of the waste. Beneath the grinder 103 a treatment and collection chamber 104 is located. A basket 105 is arranged inside the collection chamber 104 for receiving grinded solid waste, having a bottom 106 which may be closed, and which allows emptying of solid disinfected waste at the end of a disinfecting cycle. At least one wall and/or the bottom of the basket has holes or openings, preferably with a diameter approximately 3-15 mm, in order to allow water and other fluids from the grinded material to flow through into drain 109. The basket serves thus both as a collection means and a strainer for drainage of liquid material from the solid material. With a cut width of 35 mm in the grind, it is acceptable to use a basket where each hole has a diameter 3-5 mm. This will ensure that most solid material falling down from the grinder 103 will be caught in the basket 105.

In Fig. 2 the basket 105 is shown in a grinding situation with a solid-drawn line. Immediate to the right of this, is the basket 105 shown in an emptying situation with a dotted line, in this situation the waste is emptied into a bigger collection container 110, preferably occupied in a drawer 140 (Fig. 3). The basket 105 is brought from grinding position to emptying position with a suitable means, for example, a carrier 130 fastened to an end wall of the basket 105, and controlled by air cylinder 131. The basket is further - equipped with means (not shown) for opening and closing the bottom 106, before and after emptying the contents of the basket in the collection container 110. In order to avoid contact by the staff with warm areas of the device according to the invention, the inner housing can be equipped with a heat-insulating material.

The collection chamber 104 is in its lower part limited of a funnel-shaped bottom 107, which at the bottom ends in a drain pipe 109 or similar. The drain pipe 109 leads to a drain trap and further to a coupling for connection to the municipal drain system or the like. Nozzles are arranged in the upper part of the collection chamber 104, for supply of warm and cold water to the basket 105, directed downwards in the chamber 104. Steam nozzles are arranged for example at the bottomfunnel 107 of the chamber 104 for supply of steam for sterilization of the grinded and washed waste in the basket 105. The grinder 103 is powered by an engine via a transmission means and a chaingear, preferably localised at the lower part of the inner housing. Such an arrangement allows a very compact form of the device.

One or more nozzles or similare is/are localised in the upper part of the treatment and collection chamber 104, for supply of water in the washing step. The inlet chamber 101 is also equipped with one or more nozzles for supply of water in a washing step. This nozzle might advantageously have greater capacity than the nozzles in the treatment chamber. The main object of the nozzle in the inlet chamber is to make a rough cleaning of the waste, and also cleaning of the inlet chamber and the grinder 103 after the waste has been transported further.

The device 100 is further equipped with couplings for supply of cold and hot water, steam and electricity. Steam might however also be made internal in the device with a steam generator of known type which might be supplied with water from the water network. At hospitals however, steam is available at most positions, and a steam generator will therefore be superfluous. The device can thus be arranged compactly and requires less maintenance demanding modules. In the illustrated embodiment, the device according to the invention is equipped with a sink 120, 121 for rinsing of hands after handling the contaminated waste, which water supply and drain are integrated with supply and drain for the destruction part of the device. In a console at the hinder part of the device, there is arranged a start/stop switch 151, a warning lamp 152, a display mean 153 showing the course of the destruction process, and a printing unit 154 giving a short report of the destruction course.

Operation of the device is preferably performed with a digital control means, which preferably is placed in the hinder part of the outer housing 100a. The waste treatment is 5 preferably performed batch-wise. The control means, for example an ordinary PLS, is equipped with logic for operation of engine, water supply via the nozzles and steam.

Relevant parameters for operation of the device are pressure and temperature in cold and hot water, temperature in grinded waste and time. The temperature in the grinded waste is measured for example with a temperature indicator localized in the basket 105 for 10 collection of waste.

Use of the device

Singel-use equipment from operating rooms and the like is supplied to the inlet chamber 101 in the device, through the upper opening 102. The device is started for example with a

15 manually operated switch 151, whereafter relatively cold water, preferably at 35 °C is supplied to the inlet chamber. It is advantageous to perform the introductory flushing or washing with relatively cold water in order to avoid blood which is trapped in or stuck to the solid waste, coagulating and adhering permanently to unreachable places of the waste. Simultaneously with the start of the water flushing or immediately afterwards the grinder

20 103 starts, and grinds a few seconds in order to make holes in bigger bags and the like. The grinder stops whereaf er the inlet chamber 101 is flushed with relatively cold water for about 10 seconds. The grinder then continues, for example, about 30 seconds, in order to grind the rest of the waste. While the grinder grinds, the inlet chamber and the chamber 104 are flushed with hot water, preferably about 60 °C for about 30 seconds, in order to remove

25 organic material and make fatty substances float. The hot water flush may if desired, be executed with a tensid. Then the grinder stops and hot water and steam are added at about 100°C, until the contents of the basket have reached a temperature of at least 85 °C for at least 3 minutes. After this disinfection the device is cooled with relatively cold water until the temperature of the contents of the basket is about 50°C. The basket 105 is then brought

30 into the emptying situation, where the bottom of the basket is opened so that the contents of the basket fall down into the collection container 110.

This entire sequence is done fully automatically with the built-in control means, and the course of the destruction process may be followed at a display 153, and eventually via a printer 154. The total batch wise cycle will normally last about 10 minutes.

Claims

Claims:

1. Device for destruction of contaminated hospital waste, especially singel-use equipment from operating rooms, which are infected with blood and other body fluids, said device comprises a generally closed housing (100a) with an opening (102) for supply of waste, a grinding means (103) for disintegration of the waste, a means (105) for collection of grinded waste, the collection means being arranged in a collection chamber (104), a means for supply of water, and an agent for disinfection of the waste, characterized in that the agent for disinfection of the waste is a generator or means for supply of low pressure steam, and that the means (105) for collection of grinded waste is a basket with perforated sidewalls and/or bottom, arranged with means (130, 131) to move the basket (105) between a position for collection and a position for emptying, and a mechanism (106) for emptying the content of the basket into a bigger accumulator container (110) for disinfected waste.

2. Device according to claim 1, characterized in that the openings in the bottom and sidewalls of the basket (105) are continuos holes with a diameter of about 3-15 mm.

3. Device according to claim 1, characterized in that it provides a sink (120, 121) for rinsing of hands after handling of contaminated waste by destruction with the device according to the invention.

AMENDED CLAIMS

[received by the International Bureau on 30 November 1998 (30.11.98); original claims 1-3 replaced by new claims 1-6 (2 pages)]

1. Compact device for destruction of contaminated waste from hospitals and nursing institutions, especially disposable equipment from surgery rooms, which are infected with, and possibly contains relative large amounts of blood and other body fluids, said device comprises a generally closed housing (100a) with an opening (102) for supply of waste to an inlet chamber (101), a grinding means (103) for disintegration of the waste, a means (105) for collection of grinded waste, arranged in a collection chamber (104), a means for supply of water, and an agent for disinfection of the waste, characterized in that

- the agent for disinfection of the waste is a generator or means for supply of low pressure steam,

- the means (105) for collecting grinded waste is a strainer basket

- below the strainer basket (105) there is a liquid drain (107, 109) for a common drain system, and

- that means (130, 131) are arranged to transfer cut and drained waste from the strainer basket (105) to a collection container (110).

2. Device according to claim 1, characterized in that the means (130, 131) which is arranged to transfer waste to the collection container, comprises a power means to move the strainer basket (105) latherally between a collecting position under the grinding means and an emptying position over a collection container (110).

3. Device according to claim 1 or 2, characterized in that it comprises a mechanism (106), such as a bottom which can be opened, to allow emptying of the strainer basket into the collection container (110).

4. Device according to any of the claims 1-3, characterized in that the openings in the bottom and/or side walls of the strainer basket (105) constitutes a strainer with holes of a diameter about 3-5 mm.

5. Device according to any of the claims 1-4, characterized in that at least one nozzle for supply of flushing water for laiden waste, is in^" the inlet chamber (101), in order to reduce the residue of pollution included in the grinded waste.

6. Device according to claim 5, characterized in steam nozzles arranged at the bottom of the chamber (104), for supply of steam with temperatures over 85 °C.