Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Disinfection or sterilisation of materials or objects, in general; Accessories therefor
  • A61L2/02—Disinfection or sterilisation of materials or objects, in general; Accessories therefor using physical processes
  • A61L2/04—Heat
  • A61L2/06—Hot gas
  • A61L2/07—Steam
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L11/00—Methods specially adapted for refuse
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Disinfection or sterilisation of materials or objects, in general; Accessories therefor
  • A61L2/02—Disinfection or sterilisation of materials or objects, in general; Accessories therefor using physical processes
  • A61L2/04—Heat
  • A61L2/06—Hot gas
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Disinfection or sterilisation of materials or objects, in general; Accessories therefor
  • A61L2/02—Disinfection or sterilisation of materials or objects, in general; Accessories therefor using physical processes
  • A61L2/08—Radiation
  • A61L2/12—Microwaves
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Disinfection or sterilisation of materials or objects, in general; Accessories therefor
  • A61L2/16—Disinfection or sterilisation of materials or objects, in general; Accessories therefor using chemical substances
  • A61L2/20—Gaseous substances, e.g. vapours
  • A61L2/202—Ozone
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/64—Heating using microwaves
  • H05B6/80—Apparatus for specific applications
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B2206/00—Aspects relating to heating by electric, magnetic, or electromagnetic fields covered by group H05B6/00
  • H05B2206/04—Heating using microwaves
  • H05B2206/045—Microwave disinfection, sterilization, destruction of waste...

Definitions

• the invention relates to a method for the sterilization of toxic medical waste by thermal sterilization with steam, and an apparatus for performing the method.
• EP-A 287549 discloses a system of thermal treatment using microwaves and adding water to generate steam in order to sterilize through direct contact. This system works faster than the others; it has been found, however, that it is not fully operational in practice, because if there is an inadequate or insufficient addition of water, there is a risk of The treated waste is ignited because the microwaves heat existing metals (eg needles from syringes, etc.) to above 400 ° C. and can thus ignite paper or cotton wool in the waste. This system can therefore not be used without a security risk and therefore poses great risks for the operator.
• existing metals eg needles from syringes, etc.
• the major disadvantage of these systems is that the toxic waste has to be transported outside the hospital area.
• the toxic hospital waste must also be disposed of within a legally prescribed short period, for example within 48 hours; In the event of unforeseen breakdowns and these incinerators come to a standstill, it can difficult situations arise because the legally prescribed time can then not be adhered to and civil and criminal law consequences for those responsible can result.
• the object of the present invention was therefore to provide a disposal system for toxic medical waste, in particular from hospitals, which avoids the disadvantages mentioned above and which enables problem-free, in particular safe, inexpensive, quick and simple disposal. This object is achieved with the present invention.
• the present invention relates to a method for the sterilization of toxic medical waste by thermal sterilization with water vapor, which is characterized in that the waste is brought into direct contact with water vapor in an atmosphere which has a reduced oxygen content compared to air.
• Preferred embodiments of this method are the subject of claims 2 to 26.
• the process according to the invention can be carried out with complete exclusion of oxygen; preferably one works with a partial exclusion of oxygen, and in particular with an atmosphere which contains less than 15% by volume oxygen, preferably less than 10% by volume oxygen, and in particular 8 or less% by volume oxygen.
• the reduction in the oxygen content is expediently carried out by partially or completely replacing the oxygen-containing atmosphere (air) with an inert gas (for example nitrogen), and in particular by flushing the process apparatus with this inert gas.
• an inert gas for example nitrogen
• the oxygen reduction takes place via a suitable, commercially available molecular sieve, for example by contacting or passing air or the atmosphere through or through such a molecular sieve.
• the steam for the steam treatment is expediently generated by heating water by means of a microwave heater;
• the water and the waste are subjected to microwave irradiation in suitable containers in the same room.
• the water is preferably used in an amount of 5 to 20% by weight, based on the weight of the medical waste (correspondingly 5 to 20 l of water / 100 kg of waste).
• chemical sterilization is carried out, such as primarily sterilization with ozone;
• additional sterilization can be carried out by contacting the medical waste to be sterilized with ozone or an ozonizing substance.
• the steam treatment and the treatment with ozone can be carried out in any order at the same time, one after the other or partially overlapping.
• Ozone may be added in a sufficient amount and / or duration, it is continuously supplied ozone throughout the Anlagens ⁇ , for example by injection of O or zongis' by spraying ozone-containing water.
• the sterilization process should expediently, however, at least for part of the duration of the Steam treatment are carried out in the presence of ozone, and primarily the thermal steam treatment is carried out for the entire duration in an ozone-containing atmosphere, ie the waste to be sterilized is in contact with ozone at all times.
• the ozone can be supplied in sufficient quantities at least before the start of the heating phase, but in particular ozone is supplied during the entire process.
• the ozone can be in the form of an ozone-containing gas stream, e.g. with an ozone content of 2 to 20% by volume, or in the form of a preferably saturated aqueous solution and brought into contact with the waste.
• the production of the ozone-containing gas stream or the aqueous solution can be carried out in a manner known per se, e.g. by electrical discharge or electrochemically using a conventional ozone generator and, if appropriate, dissolving in water.
• the aqueous ozone solution is expediently supplied by spraying the solution into the waste container and / or into the reaction space.
• FIG. 3 schematically shows a device with which ozone can be removed via line (35) and water or water saturated with ozone via line (36) at the same time or alternatively:
• the ozone generator (37) is with a mixer
• the saturated aqueous ozone solution is preferably used in an amount of 5 to 20% by weight, corresponding to 5 to 20 l of aqueous solution / 100 kg of waste; the duration of the Ozoneinput ⁇ v * tion is the boiling temperature is reached (typically 90 to 120 ° C) preferably an additional 5 to 15 minutes.
• the sterilization step with ozone is expediently carried out in an atmosphere which has a reduced oxygen content compared to air.
• This atmosphere preferably also has the same oxygen content as the atmosphere of the steam treatment, even in the case of a separately carried out ozone treatment stage, which therefore does not overlap or coincide with the steam treatment.
• the step of steam treatment and / or treatment with ozone can be carried out at overpressure or normal pressure; in combination with ozone is preferably carried out at normal pressure.
• ozone it can be expedient to increase the sterilization temperature by increasing the pressure.
• reduced pressure i.e. under vacuum, which also results in a reduction in the oxygen content and more intimate mixing (better penetration) with the medical waste can be achieved when the aqueous ozone solution is released while the negative pressure is reduced, it is not expedient to maintain the reduced pressure even during the heating phase, because this reduces the temperature of the steam.
• the process is carried out under partial vacuum, ie until the beginning of the heating phase under reduced pressure, for example down to a pressure of 10 3 Pa (0.01 at), and the pressure is then increased before switching on the microwave heating to normal pressure or increased pressure.
• partial vacuum ie until the beginning of the heating phase under reduced pressure, for example down to a pressure of 10 3 Pa (0.01 at)
• the pressure is then increased before switching on the microwave heating to normal pressure or increased pressure.
• the reaction space in which the waste or the waste container is located is first flushed with nitrogen and then evacuated, or first evaluated and then flushed with inert gas under reduced pressure, using a vacuum holding valve, and while maintaining the vacuum, a saturated aqueous ozone solution is sprayed into the waste container and / or the reaction space; after that, before switching on the microwave heating, normal pressure is restored by opening a valve or an overpressure is also applied.
• Working with excess pressure can increase the temperature of the water vapor and thus the efficiency of the sterilization;
• Working at overpressure requires special measures, such as a pressure chamber.
• Working with overpressure or at temperatures around or above 120 C, for example at 120 to 125 ° C, is particularly expedient if only thermal sterilization with water vapor takes place, ie without ozone sterilization.
• the heating system is arranged so that the microwaves generated cover every part of the reaction space.
• the reaction space is preferably a chamber, of which at least one wall is located next to and / or below the waste container, e.g. the lower wall (floor) and / or the side walls contains a microwave heating system (magnetron).
• At least the upper boundary wall (cover) of the chamber is preferably equipped with a device for cooling, and is intended for flow through with a cooling medium, e.g. double-walled.
• Conventional containers can be used as containers for the medical waste, preferably waste cardboard boxes or a similar material, which are commercially available as folding boxes (folding boxes).
• the boxes with temperature-resistant PE inner bags or waterproof polyethylene (PE) coatings are preferably used.
• the top of the carton is preferably one Provide cover and a supply opening through which, for example, a movable trunk, which contains several supply lines in the interior, can be passed.
• the containers generally have a capacity of 30 to 80 liters, in particular approximately 40 liters, for holding approximately 7 to 12 kg of medical waste.
• the arrangement and dimensions of the individual parts of the apparatus are particularly dependent on the amount and type of waste to be sterilized and are preferably selected so that a sufficient amount of water vapor and ozone is present for the entire duration of the process.
• one or more of the containers filled with medical waste are placed in a closable chamber which forms the reaction space and is provided with a vapor tube for the removal of the water vapors which form.
• nitrogen is introduced through one of the supply pipes inside the mobile trunk inserted into the waste container and through several pipes attached to the lower part of the chamber until the oxygen content of the air is below the desired value, preferably below 15% by volume, and in particular below 10% by volume, has decreased.
• 0.2 to 3 1, preferably 1 to 2 1/7 to 12 kg of medical waste (corresponding to approx.
• the microwave heater preferably has a power that is designed so that the added water is heated to the boiling point in about 5 minutes (about 1 to 3 KW / container, for 4 containers, for example, a power of 4 to 12 KW) . Heating the water and the associated reduction in the solubility of ozone favors the formation of an ozone cloud, and the disinfecting and sterilizing effect of ozone is greatly increased by the presence of moisture. At the same time, the sterilizing effect of water vapor comes into effect at high temperatures.
• the microwave heating increases the temperature up to the boiling point of the water. As a rule, sterilization times of 5 to 15 minutes are sufficient to obtain a 100% guarantee of the destruction of all pathogenic germs.
• ozone is also added during the heating phase by means of a strong spray, which ensures a sufficient ozone atmosphere during the entire duration of the thermal treatment with water vapor.
• the heat treatment (heating phase), which is preferably about 5 to 15 minutes, is ended by switching off the heating.
• the cooling is expediently supported by the supply of a coolant, e.g. by flushing with a cold stream of nitrogen (preferably from room temperature); preferably the top of the reaction space, e.g. the lid of the microwave chamber and / or the lid of the waste container is cooled. Cooling the lid of the waste container is e.g. possible via the nitrogen supply in the mobile trunk.
• the process according to the invention can also be carried out continuously in a suitable plant, for example in a tunnel, a turntable or a similar technical device under pressure or at normal pressure with or without the use of ozone.
• a preferred embodiment of the method according to the invention is characterized by the following process steps carried out in succession: a) introducing one or more waste containers, in which the waste to be sterilized is located, into a chamber provided with a microwave heater and an exhaust pipe, b ) Lowering the oxygen content in the interior of the chamber to less than 15% by volume, c) spraying water or an aqueous ozone solution into the waste container and / or into the interior of the chamber, d) switching on the microwave heating and heating to produce of water vapor sufficient temperature with or without supply of ozone and e) cooling.
• the treatment system is preferably equipped with various, mostly double-acting safety devices:
• the heater will not start unless water or an aqueous ozone solution is added.
• the inside of the plant is monitored by pressostats. Despite the reduction in oxygen, a C0 2 detector with sprinkler system is provided in order to be able to fight possible fires immediately.
• the escaping vapors are condensed and then chemically, e.g. sterilized by ozone and / or, independently, by UV radiation; this means that both air and the escaping water are completely harmless.
• FIG. 1 shows a schematic illustration of a device suitable for carrying out the method according to the invention in longitudinal section (FIG. 1A) and cross section (FIG. 1B):
• a chamber (17) designed as a pressure chamber for receiving and sterilizing medical waste contained in a container is provided on its upper part with a vapor tube (6) for vapor discharge;
• a microwave heating system (21), for example magnetrons, is integrated in the bottom and on the sides of the chamber;
• the cover of the chamber (23) is double-walled, and with supply and discharge lines (24) for a coolant, e.g. Nitrogen gas.
• a coolant e.g. Nitrogen gas.
• This container (18) can be closed by suitable closable openings
• a mobile trunk (19) designed as a filling plunger is inserted, which has several feed lines (hoses) for the ozone-containing gas (3) for water or a saturated aqueous one Ozone solution (2) and / or for an inert gaseous coolant, for example nitrogen
• Suitable devices for measuring and controlling the temperature (8), the pressure (9), the oxygen content (4), the moisture level (10) and for C0 2 monitoring (5) are provided on the vapor tube (6).
• a sprinkler system (7) with a feed line (25) leading through the chamber ceiling 1 is provided on the chamber lid in the interior of the chamber (17).
• the chamber (17) is additionally provided with supply lines for ozone and / or coolant into the chamber space (22) and / or the waste container
• the supply lines for water or the aqueous ozone solution are preferably provided at their ends with spray nozzles. If the chamber (17) is intended to accommodate a plurality of waste containers, for example four containers, it is expedient to also provide the chamber with a plurality of vapor tubes or additional openings for the introduction of a plurality of mobile proboscis and / or feed lines for water and / or ozone and / or to provide coolant.
• the invention therefore also relates to a device according to claim 27 for carrying out the method according to the invention for sterilizing medical waste, comprising a chamber (17) which is provided with a vapor tube (6) and a microwave heating system (21) for heating of the chamber interior (22) is equipped.
• the device according to the invention is preferably provided with feed lines (1) for introducing an inert gas and / or with a molecular sieve for reducing the oxygen content of the chamber atmosphere; using a molecular sieve, the oxygen content is reduced by bringing the chamber atmosphere into contact with a molecular sieve attached to the inside (22) of the chamber (17), or by passing the chamber atmosphere through a molecular sieve in a circuit provided with a pump, or by passing oxygen-poor air (generated by absorption of oxygen with external molecular sieves)
• the cover (23) of the chamber for the flow of coolant is preferably double-walled and provided with supply and discharge lines (24) for the coolant.
• the chamber (17) with feed lines for water or an aqueous ozone solution, for ozone and / or an inert, gaseous coolant, for example nitrogen, is in the chamber space (22) and / or in the Chamber (22) located waste container (18) equipped.
• the device is preferably additionally provided with one or more of the following devices: a) a device for preferably automatic spraying of water or aqueous ozone solution in the chamber and / or a waste container located in the chamber at the start of a process cycle, b) an automatic fire protection control connected to a sprinkler system (7), c) automatic measuring and control devices for temperature (8) , Pressure (9), oxygen content (4) and / or degree of moisture (10) inside the chamber (22).
• a device for preferably automatic spraying of water or aqueous ozone solution in the chamber and / or a waste container located in the chamber at the start of a process cycle b) an automatic fire protection control connected to a sprinkler system (7), c) automatic measuring and control devices for temperature (8) , Pressure (9), oxygen content (4) and / or degree of moisture (10) inside the chamber (22).
• the device is preferably provided with a known device for direct or indirect cooling for condensing the vapors emerging from the vapor tube (6), for example with a tube provided with a cooling coil or a cooling jacket through which the vapor stream is passed.
• FIG. 2 shows an embodiment of such a device.
• the cooling device (13) through which cooling water flows is preferably a device for a chemical sterilization which is also known per se, for example by means of ozone (ozone filter 14) and / or for sterilization by UV radiation of the condensed vapors (UV lamp 11) connected downstream.
• the chamber with the additional devices consists of a material which is resistant to the sterilization atmosphere (water vapor, ozone), preferably of anodized aluminum, powder-coated aluminum, chromed metal parts and / or stainless steel.
• a waste container of 40 liters containing approximately 10 kg of hospital waste is placed in a device according to FIG.
• a mobile trunk (19) which contains supply lines for water or an aqueous ozone solution, ozone gas and nitrogen or inert gas, is inserted into the central opening of the waste container lid.
• Nitrogen is introduced through a feed line of the mobile proboscis and through feed lines (1) located at the bottom of the chamber until the oxygen content of the chamber atmosphere has dropped to a value below 15% by volume.
• About 2 l of water or a saturated aqueous ozone solution are sprayed in via the ozone feed line, which is provided with a spray nozzle at its end which dips into the waste container. Then the microwave heating (2.5 KW) is switched on.
• an ozone cloud quickly forms in the chamber, which is immediately disinfectant and sterilized. acts sieren. This effect is greatly increased by introducing ozone gas and by the presence of the water vapor, and the sterilizing effect of the hot water vapor comes into effect parallel to the sterilizing effect of ozone. After the boiling point of the water has been reached (after approx. 5 minutes), the mixture is heated at this temperature for a further 10 minutes.
• the supply of ozone is continued throughout the heating phase in order to ensure a sufficient ozone atmosphere for the entire duration; the lid of the waste container is cooled by nitrogen from the nitrogen line of the mobile trunk, which causes condensation of the water vapor and the condensate to be loaded with ozone again.
• the supply of ozone is maintained in order to achieve an optimal sterilization effect due to the high moisture content. Excess ozone also simultaneously exerts a sterilizing effect on the escaping vapors and destroys any unpleasant-smelling substances based on amine or sulfide that may be present.
• the cooling can be accelerated by introducing nitrogen through the inlets (5) in the bottom of the chamber. It is cooled to ambient temperature and the waste container is then removed from the chamber. Practically 100% sterilization of the medical waste (destruction of all pathogenic germs) is achieved.
• the system according to the invention it is possible to reduce the disposal costs for medical waste to more than half. It is also possible to Treating the waste with high efficiency at the point of origin and converting it into problem-free waste that is comparable to normal household waste, transported safely and can be deposited at landfills at low cost or destroyed in conventional incineration plants. Accidents due to self-ignition can be safely avoided according to the invention and the time required (duration of a sterilization cycle) can be greatly reduced.
• the ozone used according to the invention can easily be generated at the application site and can be removed completely and easily (for example by activated carbon or catalysts, whereupon it decomposes into harmless oxygen), so that there is no environmental pollution.
• the method and the device according to the present invention thus provide a disposal system for medical waste which can be carried out simply, inexpensively, safely and quickly and with which a practically complete sterilization without environmental impacts is achieved. It is applicable to all pathogens occurring in medical waste (microorganisms, viruses, vegetative forms of germs, spores, parasites, fungi, etc.).

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• Health & Medical Sciences (AREA)
• Veterinary Medicine (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Epidemiology (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Apparatus For Disinfection Or Sterilisation (AREA)
• Processing Of Solid Wastes (AREA)

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ID=6379346

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Cited By (10)

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• 1989
  • 1989-04-24 DE DE3913472A patent/DE3913472A1/de active Granted
• 1990
  • 1990-04-23 WO PCT/EP1990/000651 patent/WO1990012601A1/de not_active Ceased
  • 1990-04-23 AT AT90906211T patent/ATE115413T1/de not_active IP Right Cessation
  • 1990-04-23 EP EP90906211A patent/EP0470116B1/de not_active Expired - Lifetime
  • 1990-04-23 DE DE59008034T patent/DE59008034D1/de not_active Expired - Fee Related

Patent Citations (3)

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