Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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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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-
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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
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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
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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
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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
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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
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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.
