CA1146714A

CA1146714A - Process for the sterilization and disposal of infectious materials, such as hospital waste and the like and apparatus for performing the process

Info

Publication number: CA1146714A
Application number: CA000365539A
Authority: CA
Inventors: Alfred Drauschke
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-12-10
Filing date: 1980-11-26
Publication date: 1983-05-24
Also published as: EP0031790A1

Abstract

Abstract of the Disclosure The present invention relates to a process which serves especially the sterilization and disposal of infectious materials used, for example, in connection with various kinds of hospital waste but may also be present in the form of infected food and the like. Said process includes a vacuum-steam sterilization, the materials, as far as wet waste, for example spoiled blood, residues from the operating theatres of hospitals, pathological departments is concerned, being exposed to a homogenization of the sterilized substance followed by drying whereas generally, homogenization is not necessary with dry infectious materials.

For the latter materials it is particularly ad-vantageous to perform the process by using a sterilizer which, mounted on a vehicle and the like truck, makes it possible to combine infectious materials used at different places and to sterilize same in said sterilizator serving as container and being connected to a suitable steam-vacuum-source.

Description

71~

The present invention relates to a process for the sterilization and disposal of infectious materials as well as to an apparatus for performing this process.
The law lays down very stringent requirements con-cerning the sterilization of infectious, contaminated materials in the interests of the health and welfare of the population.
Thus, it must be ensured in all cases that material contamin-ated with viruses, bacteria and similar pathogenic agents, together with material used in the infectious diseases units of hospitals do not pass into the general environment in uncon-trolled manner before being adequately sterilized. E'or example it has hitherto been conventional practice to collect into special containers bandages, disposable syringes, swabs, paper towels, paper underclothing and similar material used in hos-pitals. It is then made sterile in a sterilization department within the hospital or is burnt, whilst adhering to special safety measures.
The refuse disposal law states inter alia that parts of the body and organic waste from pathological, surgical, gynecological and obstetric departments, as well as the blood bank and the like must generally be burned, "

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- 2 -whilst food and kitchen waste, particularly from the infectious diseases areas of hospitals require a special sterilization treatment.
It has hitherto been attempted to meet the requirements of the refuse disposal law by equipping at least the larger hospitals with refuse sterilization plants and in part also inci~erators in which the aforementioned waste materials are collected and made harmless in an autoclave. However, such installations are not only extremely labour-intensive, but also give rise to an increased - contamination risk for the immediate and wider environment, whilst aleo prejudicing the environment through the smoke produced when burning the waste material in a fire. A
considerable expenditure of energy is required in starting and maintaining the fire and in addition with the generally encountered discontinuous installations the hospital waste, which cannot be added to the general refuse or garbage, can only be burnt when the installation has been adeQuately heated and supplied with thermal energy.
~ he manual discharge of the autoclave or at least the manual control of this process offers many possibilities for errors to be made and constant maintainance is also required of the transportation means to and from the refuse sterili~ation plant and as far as possible they must also be kept sterile.
~- In addition, washing and disinfecting plants with the necessary high investment costs are unavoidable. Due to the necessary high thermal requirement it is obvious that an incinerator using a fire for pasty or wet hospital waste is liable to faults, -"hich further complicates the problems which already exist with such installations. In practice it is difficult, if not impossible, to carry out the necessary subdivision of the installation into a clean side and an unclean side. This greatly increases the running costs of hospitals. Sterilization installations which meet the legal requirements must be set up individually for each hospital or existing installations must be continuously monitor-ed and if necessary further improved or replaced by new instal-lations meeting the higher requirements.
The present invention therefore provides an improved process of the type initially defined in which completely satis-factory, sterilizing processing of infectious materials or wastes is ensured without prejudicing the environment and with an optimum solution of the energy problem for disposal. In ad-dition, particularly for dry and voluminous materials a centralization of the sterilization process is made possible.
According to one aspect of the invention there is pro-vided a process for the sterilization and disposal of infectious material which cannot be disposed of with the normal refuse or garbage, which comprises randomly combining the material in sealed disposable containers; moving the sealed disposable con-tainers to a central disposal installation; exposing the con-tainers and their contents in the disposal installation to a vacuum-steam sterilization process in a sterilizer and mechani-cally homogenizing undestroyed parts of the contents; drying the contents to a moisture content of approximately 10%; and re-moving the thus obtained easily burnable product from the steri-lizer on a clean side remote from the charging point of the dis-posable containers. In accordance with a further aspect of the present invention there is provided a process for the steri-. _ 3 _ lization and disposal of infectious material, ~7hich comprisescombining the materials at random in sealed disposable contain-ers at a collecting station; feeding the disposable containers into a sterilizer mounted on a mobile vehicle driven to the col-lecting station; driving the mobile sterilizer to a steam and vacuum station; effec-ting within the sterilizer a vacuum-steam sterilization process, including the alternating use of steam and vacuum, and after performing the vacuum-steam sterilization pro-cess removing the sterile material Due to the fact that the hospital waste from the differ-ent areas can be combined ~ 3a -i'71 together at random in disposable transportation containers which can then be permanently sealed for conveying to a central disposal plant, which is based on a per se known vacuum-steam sterilization apparatus and that the homogenized product undergoes drying, the following advantages are obtained:
~ he hitherto necessary individual plants for virtually every large hospital with their short-comings are made unnecessary and can be combined into a plant, which is preferably installed in the immediate vicinity of a refuse incineration power station, which constitutes a considerable improvement to the overall disposal. The hitherto indispensable labour-intensive loading and handling involved in the known refu~e sterilization installations and the waste from incinerators are almost completely eliminated. The energy required for the fire used in incinerators and the ; unavoidable defects and repairs required within the incinerator due to the considerable temperature gradients which occur are also no longer a problem in the inventive process, The contamination problems of the hitherto known and constantly reused containers, their transportation means and other accessories no longer occur and there is also no need for the relevant washing and disinfecting installations.
~0 '~he subdivision into a so-called unclean and a clean side of the sterilization inætallation can easily be realized and in fact suggests itself if, in advantageous manner, a drum sterilizer is usedO Thus, according to the invention ?
~5 both the investment and the general running costs can be considerably reduced, considerable importance also being attached to the energy savings and the benefits to the environment.
Furthermore ce~rtain hygenic inadequacies of the hi5therto employed burning of hospital waste, e.g. due to the inadequate burning of pathological organic material are reliably prevented, The combining o~ the disposal in a single installation, for example for a city having a number of hospitals, admittedly makes it necessary to reload disposable containers and to transpor-t them to the central disposal installation, but it must be stressed that it was also hitherto unavoidable to carry out a manual reloading of the containers used in the recycling system and it was not possible to completely exclude r~s~s of injury to the transportation personnel. ~his no longer occurs with the disposable plastic containers, which can be fed into the drum sterilizer or the like together with the waste material.
The overall process operates with maximum operational reliability and minimum need for repairs. ~he energy required for operating the steam sterilizer is, for example, taken from the waste steam of a refuse incinerator of an adjacent power station, to which it is possible to supply the residue or the product obtained from the process which has a high calorific value. A not inconsiderable amount of exces~ heat is produced, because approximately 1 kg of steam is required for the sterilization and drying of one kg of organic waste which, in view of the heating and radiation losses corresponds to approximately 600 kcal., giving a burnable residue of 0.3 kg with a cal~rific value of 5800 kcal., i.e. an energy gain of in all 1740 kcal. As compared with this for burning 1 kg of organic waste according to the known method using a fire approximately 0.3 to 0.5 kg of fuel oil is required in a combustion furnace, which corresponds to an expenditure of energy of approximately 3000 to 5000 kcal. giving as the end product ash, i.e. a material which cannot be reused.
According to the first and preferred embodiment of the present process the following procedure is used:
Hospital waste, such as organic residues ~- from operating theatres, pathological departments or wet or dry infectious waste, together with waste materials from the urological, gynecological and obstetric departments, as well as laboratories, which cannot be disposed of in the normal refuse or garbage are placed together with waste such as spoiled blood, residual medicaments and their packings, disposable syringes, empty glass and plastic containexs 9 worn-out metal instruments and the like in transportation-proof and substantially non-destructable, reliably sealed disposable containers. ~hese - 30 containers are optionally stored in deep-freezing plants until the time is right for transportation to the central disposal station~ ~his takes place in special refrigerated vehicles in a way which is in no way prejudicial to the environment. ~hus, even in the case of accidents the disposable containers remain sealed on the transportation vehicle and although they may be deformed, they cannot be destroyed.
At the central disposal plant the disposable containers, together with their content and without being opened are fed directly into a vacuum-steam sterilizer or preferably a drum sterilizer~ being exposed to a steam pressure of 4 atm and a minimum sterilization temperature of 134C.
The drum sterilizer is designed in such a way that it ensures in per se known manner a mechanical crushing and homogenization of parts which cannot be destroyed by the elevated pressures and temperatures, such as the disposable container, medicine bottles, disposable syringes and the like. The homogenizate resulting from this sterilization process is then dried to a moisture content of only approximately 10~ in a following - drier or in the drum sterilizer itself. ~his leads to a flour-like or granular, burnable product wi~h a very high calori~ic value equivalent to that of coal. ~his can be removed from the so-called clean side of the sterilizer and can then be supplied to a storage means or directly to an energy generator, such as a refuse incineration power station or the like.
It is important for the second preferred embodiment of the invention, which is particularly adva~tageous for dry, voluminous materials, that the vehicle transporting the infectious materials is to a certain extent the sterilizer or in the form of a truck or lorry carries the sterilizer in the form of a pressure vessel. Such a vehicle can without difficulty be driven up to any collecting station for infectious waste or to a storage station for spoiled or infected foodstuffs and the like. It then takes up the material and 7 whilst sealing it hermetically from the environment, travels to a r~ndom, suitable steam supply where the sterilization process can be carried out directly in the vehicle pressure vessel, without a further reloading into a stationary sterilizer being necessary.
In view of the amount of infectious waste materialæ obtained from a built-up area such a special vehicle can dispose of the waste from a large number of hospitals or similar inætitutions.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the sterilization and disposal of in-fectious material which cannot be disposed of with the normal refuse or garbage, which comprises randomly combining the mater-ial in sealed disposable containers; moving the sealed dispos-able containers to a central disposal installation; exposing the containers and their contents in the disposal installation to a vacuum-steam sterilization process in a sterilizer and me-chanically homogenizing undestroyed parts of the contents; dry-ing the contents to a moisture content of approximately 10%;
and removing the thus obtained easily burnable product from the sterilizer on a clean side remote from the charging point of the disposable containers.

2. A process for the sterilization and disposal of in-fectious material, which comprises combining the materials at random in sealed disposable containers at a collecting station;
feeding the disposable containers into a sterilizer mounted on a mobile vehicle driven to the collecting station; driving the mobile sterilizer to a steam and vacuum station; effecting with-in the sterilizer a vacuum-steam sterilization process, includ-ing the alternating use of steam and vacuum, and after perform-ing the vacuum-steam sterilization process removing the sterile material.

3. A process as claimed in claim 1 or 2 in which the infectious material is hospital waste.

4. A process as claimed in claim 1 or 2 in which the infectious material is organic waste from operating theatres and pathological departments and infected foodstuffs.

5. A process as claimed in claim 2, in which the infectious material is dry.