WO1994000162A1 - Method and installation for sterilizing and decontaminating hospital waste and processing it to a secondary raw material, as well as the use of the raw material thus produced - Google Patents

Abstract

Described is an installation and method for sterilizing/decontaminating hospital waste and processing it to a secondary raw material, the method comprising the following steps: (a) the unsorted waste is fed into an externally heated container which is then partly evacuated; (b) the container is filled with steam at an overpressure; (c) the waste is subjected to a period of sterilization and a first shredding operation; (d) the waste is compressed and transferred to a compensation container; (e) the compensation container is partly evacuated and then filled with steam at an overpressure; (f) the waste is transferred to a second compensation container; (g) the waste is finely shredded and dried.

Description

Process and plant for sterilizing and detoxifying hospital waste and for processing it into a secondary raw material, and its use

DESCRIPTION

The invention relates to a method and a system for sterilizing and detoxifying hospital waste and for processing it into a secondary raw material, and the use thereof.

Methods and systems for sterilizing and / or detoxifying hospital waste are known. These usually work according to similar principles, with the waste from separate collection containers being filled into a feed container via a mechanical feed device similar to that which is used, for example, in refuse transport vehicles. The waste is then comminuted within a closed system, sterilized and or detoxified at elevated temperatures and preferably by means of steam and thus processed to such an extent that the now decontaminated and sterilized, shredded waste can be deposited in a landfill for environmentally harmless disposal .

A device for disinfecting and sterilizing infectious hospital waste with flowing saturated steam is known from German utility model G 91 12 202.3. The system can be used as a mobile or stationary system. The operation of the known disinfection system is comparatively uncomplicated, with contaminated waste being filled into a filling funnel with the lid open using a tilting device and shredding in a cutting mechanism after the lid has been closed to granule size. Comminuted material is then sterilized in a long screw conveyor by multiple exposure to steam and heat over a longer period of time, poisoned and finally discharged for disposal. A disadvantage of this and similar systems for the disinfection of hospital waste is the increasing amount of waste with the discharge thereof in ever smaller landfill rooms.

On the basis of this prior art, the object of the invention is to specify a method and a plant for the sterilization and detoxification of hospital waste and for its processing into a secondary raw material, as well as its use, which make it possible instead of the costly final storage of the waste to obtain a secondary raw material from it in landfills which is suitable for a useful and occasionally profitable use, for example for the production of simple objects or for use as a useful auxiliary.

To solve the problem of the method of the type mentioned, a sequence of work steps according to the characterizing part of claim 1 is proposed.

The fact that the waste in its packaging, usually in garbage bags, is batch-sorted unsorted using an mechanical, heating device and an externally heated, autoclave-like container means that contact of this waste with the people involved in disposal is completely avoided.

What is new and advantageous in this method is the step in which the autoclave-like container is closed on the input and discharge sides after filling and is first partially evacuated by suction of air and / or gas. Because this significantly improves the decontaminating and sterilizing effect of the steam that subsequently flows in and builds up pressure. Only after this step is the connection between the container and a first mechanical comminution stage released and the waste components are pre-comminuted in this comminution stage after tearing open and crushing their packaging under the influence of the steam atmosphere and thereby pre-mixed. This comminution under the influence of steam and under the influence of temperature, caused by a preferably electrical trace heating located on the container, is hay and particularly advantageous because, on the one hand, the waste is already partially digested and affected by the action of steam and heat are pre-sterilized and pre-decontaminated and are therefore broken down even more intensively in the subsequent work steps and neutralized or destroyed proportionate toxic substances or pathogens with the highest possible efficiency.

The subsequent multiple compression and decompression of the substances and their at least repeated throughput through two expansion tanks with a sequence of parts evacuation and subsequent steam application under pressure complete the sterilization and decontamination of the premixed and pre-comminuted waste to the highest possible degree of perfection. These are now given a second size reduction step beyond the usual size of known processes. In it, the temperature is increased by comminution or material grinding according to the steam flow method by means of tensioned, saturated water vapor with simultaneous action of the knives on the comminuted material, so that residual water and other residual moisture are at least partially evaporated and the drying process already begins here. The fine comminution material is then subjected to thermal drying on a case-by-case basis and discharged from the system as a secondary raw material for further use.

In one embodiment, the waste is subjected to fine grinding in the grain size range between 1 and 3 mm in the second size reduction stage. It is also new and advantageous that according to one embodiment, the waste in the first size reduction stage is compacted by adjustable material accumulation in order to influence the degree of pre-size reduction in a targeted manner. An embodiment further provides that the pre-comminuted waste mixture in the second comminution stage is also compressed by adjustable material accumulation in order to influence the final degree of comminution in a targeted manner. These measures provide a great advantage in the possibility of setting the degree of pre-comminution or the final degree of comminution of the waste within comparatively broad limits in accordance with the requirements of the process or in accordance with the results to be achieved.

This process is also supported in that the comminution is carried out by a sequence of cutting and / or shearing processes or crushing operations using helical cutting knives of a cutting rotor which cooperate with cutting knives fixed in a cutting housing.

For this purpose, an embodiment provides that the cutting rotors are driven at different speeds in accordance with the intended degree of comminution. For example, the speeds in the fine grinding stage are significantly higher than in the pre-grinding stage. The cutting rotor can also be driven with alternating directions of rotation to influence both the degree of comminution and to loosen the material to be cut. A further advantageous embodiment of the method results from the fact that a force component is exerted on the material to be cut in the conveying direction using helical cutting knives of the comminuting rotors. If this force component is then counteracted, for example by throttling, the comminution rate of the material to be cut can thus be variably set within comparatively wide limits.

One embodiment provides that the steam is injected into the container at pressures between 5 and 6 bar at approximately 155 ° Celsius, the pressure and / or temperature being continuously monitored automatically.

An advantageous embodiment of the method results from the fact that the feed units are opened and closed in such a time-controlled manner that at least two are always closed while a third is open. This method of operation ensures that excess pressure, which is built up, for example, in the individual expansion tanks, cannot escape from the system. The working pressure in the expansion tanks is between 500 and 700 mbar, the steam temperature here is approx. 115 ° C.

The exhaust gas or exhaust air drawn off is or are cleaned and detoxified by a multi-stage activated carbon filter before being emitted to the outside atmosphere. Furthermore, the hot air used for drying is preferably conducted in a circuit, the vapors being condensed and the air being filtered by suspended particles carried along.

A system for sterilizing and / or detoxifying hospital waste and processing it into a secondary raw material to carry out the invented method according to the invention has an arrangement of system elements in accordance with the characterizing part of claim 14. Further advantageous configurations are provided in accordance with the subclaims.

The use of the secondary raw material produced by the process according to the invention can be provided, for example, as an adsorptive material for binding harmful fluids such as oil or leaking harmful chemicals, for cleaning the environment. Furthermore, there is the possibility of using the secondary raw material as a starting material for further processing into compression moldings under the action of heat and pressure, for example for bases, flower boxes and the like. When used in this way, the intended use benefits from the fact that the waste contains statistically approximately reproducible proportions of cellulose, cotton and plastics which, with an extremely high degree of comminution of the secondary raw material, result in an extremely absorbent mass for binding harmful fluids, and on the other hand as a result of thermoplastic property of the plastic parts when pressing to form parts under pressure and temperature develop a sufficient bond quality for the production of dimensionally stable pressed parts.

The plant according to the invention is shown in a schematic, family tree-like drawing in a preferred embodiment, further advantageous details of the invention being apparent from the drawing. The system shown in the figure has an autoclave-like externally heatable and heat-insulated feed pressure container 1 with an associated lift-tip feed device (not shown). A specially designed weighing device, preferably with an automatic result printout, is located on this feed device for the exact weight recording of the treated waste. The pressure vessel 1 is equipped with a pressure-tight lockable cover 2. It has a preferably electrical jacket heating and means 20, 22 for steam injection. Furthermore, the system has a suction device 30 to 33 for suction and for neutralization or decontamination of toxic vapors or gases or contaminated with disease germs or Air. The suction device 30 comprises an active carbon filter 31, a downstream exhaust port 32 and a suction line 33 with a shut-off device 34, which merges into a ring line 35 with connections 36 to the container 1.

A first comminution device 4 is arranged on the underside of the feed container 1, and a discharge pipe 7 with a gate valve 3 and a first piston conveying device 10 for comminuted mix material are assigned on the discharge side. This promotes the discharge of the first comminution device 4 into an externally heatable first expansion tank 5. This is connected to the suction device 30 or its ring line 35 with a connection 37 and has means 20, 22 for steam injection. To monitor pressure and temperature, the expansion tank 5 is equipped on its lid with a manometer 23 and a thermometer 24 as well as with a fully electronic pressure and temperature monitor. A material conveying line 18 leads from the expansion tank 5 to a second expansion tank 6. Both expansion tanks 5 and 6 are heated and electrically insulated with an electric trace heating and each have a connection 38 to the suction device 30 and means 20, 22 for steam injection. The second expansion tank 6 comprises a second piston conveyor device 11. This expansion tank 6, like the first expansion tank 5, is monitored electrically. A discharge lock 15 and an intermediate conveyor 14 are connected to this second conveyor 11. This feeds pre-comminuted and partially prepared mix into an intermediate container 9, which has a second comminution device 8 with a discharge lock 16 in the lower region. From the second comminution device 8, the finely comminuted material then arrives at the belt conveyor 39 via the shut-off device 16 and is fed to the drying drum 40 with it and dried therein with hot air from the hot air generator 41 to the end product. The system also has a hydraulic station 26 and a control unit 27. In the shredding devices 4 and 8, it is advantageously provided that they are designed as shredders with radially projecting knives having shredder rotors, each of which is arranged so as to be driven in a rotating manner in a housing surrounding the rotor and equipped with knives facing inwards. The knives of each rotor and / or of the housing can be very helically shaped. This will be a particularly intense one Cutting and shearing effect achieved, and preferably in the Feinzerkleinerungs¬ stage the material in the interaction of the inner and outer knives very finely chopped or chopped during the rotation of the rotor. The cutting units can advantageously be operated under material jam with an adjustable degree of comminution, and the cutting rotors can also be driven at different speeds in accordance with the intended degree of comminution. The higher the speed is set, the more intensive the degree of comminution of the cutting device. A cutting rotor of a shredding stage can also be driven to influence both the degree of shredding and to loosen the material to be cut with alternating directions of rotation. The material of the cutting units consists of high-quality tool steel, whereby it is crucial that all materials, that is to say cutting knife and knife, rotor knife and retractable parts, are made of the same material. They are then titanium-implanted in a special procedure. The cutting unit is advantageously designed in such a way that all parts can be exchanged in modular design. For example, the structure of the cutting unit of the fine size reduction stage is similar to the cutting unit of the pre-size reduction level, but with a shorter paddle arm of the cutting blade. The knives can have spiral hollows between the helical blades, which are the same or different in number and size. It has proven to be advantageous that the cutting unit of the pre-comminution stage is operated at a speed of 60 rpm and is operated in the direction of rotation forward and then reversing according to a predetermined rhythm. The speed of rotation in the fine comminution cutting unit is 100 rpm, the cutting rotor also being able to be operated alternately with a change in speed.

A horizontal arrangement of the cutting rotors can advantageously prevent elongated parts such as e.g. Dialysis tubing made from dialysis filters, syringes or channels can be pressed undrilled vertically through the rotor and stator knives and thus run through the system in a non-sterilized manner.

The system described above can also be used, for example, to shred files using the modular structure, in which case the electrical trace heating and the steam supply are switched off become. This is particularly important for the data protection-related destruction of the large number of medical records in the hospital area.

Claims

Process and plant for the sterilization and detoxification of hospital waste and its processing into a secondary raw material, as well as its useP ATENT REQUESTS 1. Method for sterilizing and detoxifying hospital waste and for processing it into a secondary raw material, characterized by a sequence of work steps: a) the waste is placed in batches unsorted in batches using mechanical feeding means into an externally heated autoclave-like container, which is sealed and then partially evacuated by suction of air and / or gas. b) after the end of the suction, the waste enclosed in the container is flooded with water vapor, a vapor overpressure being built up; c) after a predetermined exposure and / or sterilization period, the waste components, after tearing open and shredding their packaging, are pre-shredded and pre-mixed in the process; d) the waste is compacted during the coarse or preliminary comminution under the action of a rotating knife and conveyed through a closed, fully insulated conveying line into a first expansion tank; e) after the container has been closed, the waste mixture is first expanded and partially evacuated with the suction of gas and steam, then flooded with steam, an excess steam pressure being built up under the sterilization effect and detoxification. f) a connection between the first expansion tank and a first feed unit is then released and the waste mixture is transferred to a second expansion tank with renewed compaction by means of alternating feed strokes through a closed, steamable or externally heated and fully insulated line, in which process step e) is then repeated becomes; g) then a connection between the second expansion tank and a second feed unit is released and the waste mixture is added to a second comminution stage and finely comminuted therein under the action of steam and heat again, or pre-dried or dried without the action of steam solely by frictional heat during comminution, and occasionally h) the fine comminution material is discharged from the second comminution stage using a further feed unit and is given to a drying stage, in which it is subjected to thermal drying with intensive rolling motion and flooding with hot drying air. i) the dried, finely ground and thoroughly sterilized or detoxified material is discharged from the system as a secondary raw material for further use. 2. The method according to claim 1, characterized in that the comminution in the two comminution stages is carried out under the simultaneous action of tense saturated steam. 3. Process according to claims 1 and 2, characterized in that the waste in the second size reduction stage is subjected to fine size reduction in the grain size range between 1 and 3 mm. 4. The method according to claims 1 to 3, characterized in that the waste in the first size reduction stage by adjustable material accumulation targeted influencing of the degree of pre-shredding during the shredding process. 5. The method according to claims 1 to 4, characterized in that the pre-comminuted waste mixture is compressed in the second comminution stage by adjustable material jam for the targeted influencing of the final degree of comminution during comminution. 6. The method according to one or more of claims 1 to 5, characterized gekenn¬ characterized in that the comminution by a sequence of cutting and / or Scher¬ processes or crushing operations using helical cutting blades of a cutting rotor, which is carried out with interact in a cutting housing fixed cutting knives. 7. The method according to any one of claims 1 to 6, characterized in that the cutting rotors are driven at different speeds in accordance with the intended degree of comminution. 8. The method according to any one of claims 1 to 7, characterized in that the cutting rotor for influencing both the degree of comminution, and for loosening the material to be cut is driven with alternating directions of rotation. 9. The method according to any one of claims 1 to 8, characterized in that a force component is exerted on the material to be cut in the conveying direction using helical cutting knives. 10. The method according to any one of claims 1 to 8, characterized in that steam is injected into the container with pressures between 5 and 6 bar at approximately 155 ° C, pressure and / or temperature being automatically monitored continuously. 11. The method according to any one of claims 1 to 10, characterized in that the feed units are opened and closed in such a time-controlled manner that at least two are always closed while a third is open. 12. The method according to any one of claims 1 to 11, characterized in that exhaust gas or exhaust air drawn off is cleaned and detoxified by a preferably multi-stage activated carbon filter before emission to the outside atmosphere. 13. The method according to any one of claims 1 to 12, characterized in that the hot air used for drying is circulated and the resulting vapors are condensed and the air is filtered by suspended particles carried. 14. Plant for sterilizing and detoxifying hospital waste and for processing it into a secondary raw material, for carrying out the method according to the preceding claims, comprising an arrangement of plant elements a) a posting station with - An autoclave-like, externally heated and heat-insulated feed pressure container (1) with an associated lift-tilt-feed device, the pressure container (1) having a pressure-tight lockable cover (2) and a closure, and means (20 - 22) for steam injection and connections (36) to a suction device (30) with exhaust gate (32) and activated carbon detoxification filter (31), and with - a first comminution device (4), preferably a coarse cutting unit, with a delivery pipe (7) for comminuted mix, and a closure member (3) arranged therein, b) an externally heatable first expansion tank (5) connected to the delivery pipe (7) with connection (37) to the suction device (30) and means (20-22) for steam injection, and with a first piston delivery device (10) arranged on the discharge side ; c) a delivery pipe (18) connected to the delivery device (10) on the discharge side and subject to steam and lined with an insulating jacket (25), a shut-off device (19) being arranged between the first expansion tank (5) and the delivery pipe (18), to which a second expansion tank (6) is connected on the discharge side, which has a connection (38) to the suction device (30) and means (20-22) for steam injection and on the discharge side a second piston delivery device (11); d) an intermediate conveyor (14) adjoining the second conveyor device (11) with a downstream intermediate container (9), which has a second shredding device (8) with a discharge lock (16) in the lower area; e) a drying station for the end product with a feed conveyor (39) connected to the discharge lock, a drying drum (40) and a device (41) for generating hot drying air with vapor discharge and exhaust air dedusting. 15. Plant according to claim 14, characterized in that the Zerkleinerungs¬ devices (4, 8) are designed as a shredder with a radially projecting knife haben¬ the rotor, the rotor in a surrounding and equipped with inward-facing knives rotatingly driven is preferably arranged horizontally. 16. Plant according to claims 14 and 15, characterized in that the feed container (1) or the lift-tilt feed device is assigned a weighing device for exact weight detection of the waste, preferably with an automatic printing unit. 17. Plant according to claims 14 to 16, characterized in that knives of the rotor and / or the housing are helical. 18. Use of the secondary raw material produced by the process according to the invention as an adsorptive material for binding harmful fluids such as oil or leaked harmful fluid chemicals, for cleaning the environment. 19. Use of the secondary raw material as a starting material for further processing, for example into molded parts under the action of heat and pressure, such as bases, flower boxes and the like.