Note: Descriptions are shown in the official language in which they were submitted.
21 2~`3g
PROCESS AND DEVIC~ FOR TREATING LIQUID-CONTAINING,
CRUS~ABLE WASTE
The present invention relates to an apparatus for processing
reducible waste that contains liquid, in particular for
processing clinical waste, with a loading system for introducing
the waste and a reducing system that is incorporated after the
loading system.
Apparatuses of this kind have been known for many years in
practice. As a rule, these are so-called choppers or shredders
of the type used for processing or reducing garden waste. Such
apparatuses are particularly suitable for reducing dry waste,
when this is chopped or cut by means of blades rotating at high
speed.
However, the apparatus in ~uestion that is already known, is
problematic if the waste contains liquids. Solely as an example,
reference is made here to clinical waste, when so-called "A"-
class and "B"-class wastes are collected in plastic bags. Such
waste originates, for example, from operating theatres and, in
addition to plastic bottles, catheters, or the like, also
contains organic substances with blood or other body fluids. If
such waste is reduced using the known apparatus, this always
results in a mixture composed of waste that has been reduced and
liquid. Such a mixture presents disposal problems, especially
since incineration of the solids is made difficult, or even
impossible, because of the high liquid content. For the
remainder, handling the mixture is extremely difficult and
scarcely reasonable as far as the operating personnel are
concerned.
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In addition, there is a further problem in that clinical waste,
in particular, must frequently be classified as infectious. Such
wastes are the so-called "C"-class wastes. Such waste is
collected in closeable plastic containers and must be specially
treated with respect to processing and subsequent disposal. This
is also impossible using conventional crushing systems, for here,
too, the mixture of solids and liquid poses special problems, as
in the case of the "A"-class and "B"-class wastes.
For this reason, it is the task of the present invention to
describe an apparatus for processing reducible wastes that
contain liquid, which makes a simple, clean, and technically
economical treatment of waste possible. In addition, it should
also be possible to subject infectious "C"-class waste to
subsequent processing. Finally, it is intended to describe an
appropriate procedure for processing reducible waste that
contains liquid.
The apparatus according to the present invention for processing
reducible waste that contains liquid solves the problem described
above with the distinguishing features set out in patent claim 1.
According to this, the apparatus used to process reducible waste
that contains liquid is characterized by a strainer system to
catch most of the solids, which is incorporated after the
reducing system, and a collecting container for the liquid that
is arranged essentially beneath the strainer system in order to
catch the liquid. It is also important that the strainer system
and, optionally, the collecting container can be removed from the
apparatus in order to be emptied.
According to the present invention, first of all it was
acknowledged that in order to process reducible waste that
contains liquid, in particular from the standpoint of subsequent
processing, it is necessary to separate the solids and the
liquids from each other. The strainer system that is
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incorporated after the reducing system and that is intended to do
this catches most of the solids, when more or fewer fine solids
can be trapped by the strainer system by the appropriate
selection of the mesh size or mesh diameter.
A collecting container is arranged beneath the strainer system so
that, in particular, the liquid that is released during the
reduction process can pass through the strainer system and into
the collecting container. In order to simplify handling of the
separated waste, the strainer system can be removed from the
apparatus in order to be emptied and, of course, in order to
clean the apparatus. Further processing or additional processing
of the solids is possible according to the particular class of
waste. The collecting container could also be made so as to be
removable, so that the liquid can be simply poured out or passed
on to a syætem used for carrying subsequent processing.
With respect to the configuration of the loading æystem, it is a
particular advantage if this incorporate a shaft that leads to
the reducing system. The waste can be loaded through this shaft
without any difficulty. This shaft is to be dimensioned such
that the containers and waste bags that are used in clinical
practice can be loaded into the reducing system as a whole,
without the need to empty said containers or bags beforehand. In
addition, the loading system has a cover that closes off the
shaft at the loading end, i.e., at the end that is remote from
the reducing system. ,IThis cover can also be used, for example,
as a ram in order to push the waste into the area of the reducing
system. In any case, it is preferable that the loading system
can be sealed so as to be air-tight by the cover, so that
operating personnel are in any case adequately protected against
fragments of waste that are expelled from the machine. Finally,
the cover forms a reliable spray shield for the event that there
is a high liquid content in the waste.
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It is preferred that the reducing system be driven by an electric
motor. This can be, for example, in the form of a spur wheel
back-geared motor~ Other types of motor can also be used.
With respect to the reducing system, it is particularly
advantageous that this incorporate a cutter assembly with
preferably two counter-rotating cutter shafts. The cutter shafts
could also advantageously be arranged in such a manner that they
draw the material that is to be cut from the shaft and into the
cutter assembly automatically. If such a configuration is used,
it is not necessary to have a special system to push or force-
feed the waste into the reducing system.
~ 'The cutter shafts could be so configured that they incorporate
splines for blades that are preferably of high-alloy tool steel.
Depending on stress and wear, the blades can be replaced
individually and, to the extent that this is possible, it is not
necessary to replace the cutter shaft.
In particular, from the standpoint of safety and in order to
avoid damage to the cutters, it is advantageous if a flexible
coupling be arranged between the cutter shafts and the motor. In
a particularly advantageous manner, an electronic torque limiter
could be installed as an overload safety device, and this would
preferably be fitted with a reversing control.
In order to ensure that the reduced waste passes into the
strainer system or the collecting container, respectively, the
reducing system is mounted directly on the collecting container.
In other words, the reducing system is mounted on the collecting
container in such a manner as to be removable and so as to
effectively seal it. The reducing system can be taken off the
collecting container for maintenance, repair, and for cleaning,
so that the strainer system is similarly accessible and
removable.
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In order that the strainer system can be securely positioned
within the collecting container, it is preferred that the
collecting container incorporate retainers on the inside, said
retainers then being used to suspend the strainer system. These
retainers could, for example, be in the form of an annular edge
that extends approximately radially inwards, the inside diameter
of this being slightly smaller than the outside diameter of an
outer edge or retaining ring on the strainer system.
If it is desired to remove the waste, trapped by the strainer
system in the ~orm of solids, from the apparatus for purposes of
disposal, and without any further processing within the
apparatus, the strainer system could advantageously be made in
the form of a vibration-type conveyor that extends to the outside
of the collec'ing container. This vibration-type conveyor could
discharge directly into an accumulator tank, from which or with
which the waste can be delivered to an incinerator. The strainer
system could also incorporate drip-trap ledges that extend
downwards within the collecting container, at least in its edge
area, in order that any "creep" caused by liquid adhering to the
lower side of the strainer system can be effectively prevented.
These drip-trap ledges could enclose the vibration container or
the strainer system within the accumulator tank.
Within the context of an alternative configuration that is
particularly advantageous with respect to subsequent processing
of the liquid that is to be collected, the strainer system could
be cup-shaped and extend into the collector container with a
conically tapered cross-section. The collector system could
extend up to a third or about half into the collector contain~r,
in which connection all that has to be ensured is that the
strainer system must not extend into the liquid that is contained
or has been caught in the collecting container.
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The strainer system could be in the form of a filter bag, for
example. Such a configuration would entail the major advantage
that the complete filter sac is provided with openings to allow
the liquid to escape. In the same way, the strainer system could
have rigid walls and a mesh bottom that closes off the walls
underneath. Here, too, it would be conceivable that not only the
sieve bottom but also the walls be provided with small openings
in order to let the liquid drip through at a faster rate.
In order that the liquid that has been collected can be drained
from the collecting container or passed on from the collecting
container for further processing without any problems, the
collecting container has in the lower area an outlet that can be
shut off by means of a valve. This could be, for example, a
drain cock in the conventional sense. In the same way, it could
also be in the form of an appropriate drain line with a
mechanical or solenoid-type valve.
In particular with respect to continued processing of the liquid
that has collected in the collecting container, it is an
additional advantage if the outlet lead to a filtering system
through a line and, optionally, through a pump, it being possible
to connect the filter system to the sewer system or the like
through an outlet and a line that can be connected to the outlet.
Draining the collected liquid in this way is only possible if the
waste that has been reduced is "A"-class or "B"-class waste.
The problem of processing "C"-class waste frsm hospitals was
addressed in the introduction hereto. This involves infectious
waste, liquid from which--body fluids of all kinds--may not be
disposed of as such even after repeated filtration. Even in the
case of adequate dilution with mains water, such "disposal" is
unacceptable, especially since the whole of the waste-water area
can become infected by infectious liquid.
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As a consequence, with respect to the teaching of the present
invention, it is a particular advantage if extensive processing
of infectious waste takes place within the framework of the
processing of waste according to the present invention. To this
end, it is particularly advantageous if an ozone generator be
incorporated outside the collecting container. Within the
collecting container, preferably in the area of its bottom, there
are nozzles, and the ozone generator is connected to these
nozzles by an appropriate gas line. As a consequence, fine
bubbles of ozone pass from below through the liquid that has
collected in the collecting container, as a result of which all
of the liquid is subjected to ozone treatment. Because of this
ozonization, body fluids of all kinds are sterilized. Albumen is
denatured ancl blood is coagulated. As a consequence, the ozone
treatment results in neutralization of the original infectious
liquids so that these can then be classified as "A"-class or "B"-
class waste.
The ozonization of the liquid that has collected in the
collecting container in the manner described heretofore entails
the added advantage that ozone rises through the liquid and then
escapes from this. As a consequence, ozone passes into the area
of the filter system and, on the one hand, disinfects the solids
that are trapped in the filter system or in the filter, and on
the other, disinfects the filter system itself. Subsequently,
the ozone passes through the filtering system into the loading
system as far as the closed cover and thus disinfects the whole
of the apparatus according to the present invention~ As a
result, not only is the waste disinfected or neutralized; the
whole of the apparatus that is used to process the waste is also
disinfected at the same ti~e.
The nozzles that are provided in the lower area of the collecting
container can, in an additionally advantageous manner, be in the
form of fine openings or bores in a line that is preferably
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arranged in spiral form. This line could, for example, be
provided with the bores in question on a semi-circular upper
section and could cover the whole of the bottom of the collecting
container in a spiral or helical shape. This would then ensure
that ozone or fine bubbles of ozone pass through all the liquid
that is in the collecting container.
In order that the ozone produced in the ozone generator can pass
into the collectin~ container at a specific pressure or flow out
through the jets provided there at a specific velocity, the ozone
generator is preceded by or associated with an air compressor
that is incorporated in order that the ozone can be acted upon by
compressed air. The ozone that has been generated is delivered
to the collecting container and forced through the liquid
collected therein by the compressor. In addition, the compressor
also serves to flush the apparatus according to the present
invention with air. A cylinder of compressed air could also be
used in place of the compressor.
From the standpoint of the continued purification of the liquid
that has been treated with ozone, it is also advantageous if a
gas line be led from the ozone generator or from the compressed
air cylinder to the outlet from the above-di~cussed filter
system. This makes further ozone treatment of the already
filtered liquid possible as secondary treatment, in order to
achieve 100 per cent disinfection of the liquid. A gas line
could also be led ~rom the ozone generator to the filter system
itself, when the gas line would then advantageously open out into
the lower area of the filter system. Thus, to this extent, once
again ozonization could be effected directly in the filter system
which would mean that the filter system itself could be
disinfected. Here, as in the case of the ozone treatment of the
liquid in the collecting container, it is important that the
ozone be supplied to the lower area of the filter system in order
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that all the parts and areas of the filter system and the liquid
contained therein be effectively ozonized.
In particular with respect to effective disinfection of the whole
of the apparatus, it is a particular advantage if, with the cover
closed, all the internal spaces of the apparatus of the present
invention are hermetically sealed. As a consequence, the ozone
can flow through the whole of the apparatus, and cannot pass
uncontrolled out of the apparatus. Then, it is preferred that a
gas filter with a catalyst, which can be closed off by means of a
valve, be arranged in the upper area of the loading system in
order to neutralize the ozone. The gas filter could, for
example, be an integral component of the cover of the loading
system. The catalyst prevents the ozone causing an offensive
odour.
The process according to the present invention perform~ the task
defined in the introduction hereto by way of the features set out ~ ~ -in patent claim 26. According to this, in the procedure
according to the present invention, this preferably involves a
procedure to operate an apparatus according to the precedin~
description. This procedure is characterized by the following
stages: -
First, the waste, if necessary together with the associated
containers or packaging material, is reduced or cut up. This
reduced waste is then trapped in a strainer system. The small
fragments and liquids that pass through the strainer system are
collected in a collecting container. If necessary, the waste
that has been reduced can be sprinkled with water. The reduced
waste that has been trapped can be removed once the li~uid has
dripped out of it. The same applies to the liquid separated from
the solids, which can be emptied from the collecting container
that is located beneath the strainer system.
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With respect to the procedure according to the present invention,
it is an added advantage if, prior to the removal of the reduced
waste and the solids separated therefrom, an additional treatment
measure take place if the waste is infectious waste from clinical
practice. For purposes of disinfection, ozone is fed into a
lower area of the apparatus that is being used so that both the
reduced waste and the separated liquid, as well as the whole of
the apparatus comes into contact with the ozone. After the ozone
treatment, the separated liquid could be drained off through a
filter system, optionally after repeated ozonization, into the
waste-water system or into a subsequent filter, since this liquid
is then completely disinfe~ted. The reduced waste that is caught
in the strainer system can be disposed of as normal household
garbage after ozone treatment.
Prior to opening the apparatus that is used for processing the
waste, the ozone is driven off in a particularly advantageous way
by repeated flushing with air, through an appropriate filter
system or over a catalyst, so that the apparatus is only opened
after being completely flushed with air.
There are a number of possibilities for configuring and
developing the object of the present invention in an advantageous
manner. To this end, reference is made, on the one hand, to the
secondary claims, and on the other, to the explanation of two
embodiments of the present invention that are shown in the
drawings appended hereto. Generally preferred configurations of
the teaching of the present invention are discussed in connection
with the explanation of the preferred embodiments of the
invention on the basis of the drawings. These drawings show the
following:
Figure 1: a diagrammatic illustration of the principles of an
apparatus according to the present invention, this
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being an apparatus for processing infectious clinical
waste;
Figure 2: a second embodiment of an apparatus according to the
present invention.
Figure 1 is a diagrammatic drawing of an apparatus according to -
the present invention, in the form of one embodiment, that is
used to process reducible infectious clinical waste that contains
liquid. This apparatus comprises a loading system 1 for
introducing the waste into the apparatus and a reducing system 2
that follows the loading system 1.
According to the present invention, the reducing system 2 is
followed by a strainer system 3 that traps most of the solids,
and by a collecting container 4 for the liquid, this collecting
container being arranged essentially beneath the strainer system
3. The strainer system 3 and the collecting container 4 can be
removed from or taken off the apparatus to be emptied.
The loading system 1 incorporates a shaft 5 that leads to a
reducing system 2 and a cover 6 that closes off the shaft 5 at
the loading end. Figure 1 also shows that the reducing system 2
is driven by means of an electric motor 7, which can be a spur -
wheel back-geared motor.
Figure 1 also shows that the reducing system 2 comprises a cutter
with two counter-rotating cutter shafts 8. The cutter shafts 8
are arranged or spaced apart such that they draw the material
that is to be cut up from the shaft 5 and into the cutter
automatically. At this point, it should be noted that the cutter
shafts 8 incorporate splines for the cutter blades that are of
high-alloy tool steel. It should also be noted that a flexible
coupling is arranged between the cutter shafts 8 and the motor 7,
and that an electronic torque limiter with a reversing control is
incorporated in order to provide overload protection.
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The reducing system 2 is mounted on the collecting container 4 in
such a way as to be removable and so as to seal it. The
collecting container 4 has on its inside retainers 9 for
installing the strainer system 3.
The strainer system is cup-shaped and tapers in cross-section
and is installed so as to extend into the collecting container 4,
the strainer system 3 extending not quite kalfway into the
collecting container. Even though the strainer system 3 can be
made in the form of a filter bag or the like, here, in this
selected embodiment, it has rigid walls 10 and a mesh bottom 11
that closes off the walls 10 underneath.
The collecting container 4 has in its lower area an outlet 13
that can be closed off by means of a valve 12. The outlet 13
leads to a filter system 16 by way of a line 14 and a pump 15,
and this filter system 16 can, in its turn, be connected through
a drain 17 and a line 18 to the sewer system or the like (not
shown in figure 1).
For treating infectious waste, in particular, it is important
that in the embodiment that is shown in figure 1 there be an
ozone generator 19 outside the collecting container 4. Within
the collecting container 4, in the base area, there are nozzles
20. The ozone generator 19 is connected to the nozzles 20 by way
of a gas line 21. Figure 1 shows that the nozzles 20 are in the
form of fine outlets or bores in a line 22 that is arranged in
the form of a spiral in the base area of the collecting
container. Such a configuration for the nozzles 20 is
particularly economical and, at the same time, extremely
effective.
In addition, an air compressor that is used to produce compressed
air that acts on the ozone that has been generated precedes or is
associated with the ozone generator 19.
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For purposes of continued ozone treatment, a gas line 24 runs
from the ozone generator 19 to the outlet 17 of the filter system
16. An additional gas line 25 runs from the ozone generator 19
to the filter system 16, the gas line 25 opening out in the lower
part of the filter system 16. Figure 1 shows that when the cover
6 is closed, all the interior spaces of the apparatus according
to the present invention are hermetically sealed. A gas filter
(not shown in figure 1) is incorporated in the upper area of the
loading system 1, and this filter can be closed off by means of a
valve. This gas filter also incorporates a catalyst to
neutralize the ozone.
As is shown in figure 2, which illustrates another embodiment, in
the apparatus shown therein, the waste that is trapped by the
strainer system 3 in the form of solids can be removed from the
apparatus for subsequent disposal, without any additional
treatment within the apparatus. To this end, the strainer sy-tem
3 is in the form of a vibration-type conveyor 26 that extends
outside the collecting container 4. This vibration-type conveyor
26 discharges directly into an accumulator tank 27, with which
the waste, separated from the liquid, can be moved to an
incinerator, for example. The strainer system 3 also has drip-
trap ledges 28 and these extend downwards from its edge area
within the collecting container 4, so that any "creep" that is
caused by adhesion of liquid on the underside of the strainer
system is effectively prevented. These drip-trap ledges 28
enclose the vibration-type conveyor 26 or the strainer system 3,
respectively, as a whole within the accumulator tank 27 and thus
limit it to the outside. However, at this point, it should be
remembered that the embodiment shown in figure 2 is less suited
for processing infectious waste ("C"-class waste).
Finally, it is emphasized that the teachings according to the
present invention are clarified on the basis of the embodiment
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described heretofore simply as an example and are in no way
confined to this.
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