TITLE: APPARATUS FOR NEUTRALISING THE BACTERIAL LOAD IN SOLID HOSPITAL WASTE

DESCRIPTION

The invention relates to improvements to the processing method and to the associated machine described in international patent application no. WO 2005/002639 published on 13-1 -2005 which are particularly suitable for microwave sterilisation of hospital waste, in such a manner that such waste may also be disposed of directly at the source, like ordinary waste, with appreciably reduced costs relative to those of current disposal procedures using specialised facilities. The method described in said patent application is characterised by the following operating phases: a) finely shredding the waste, alone or together with the collection container, in a controlled environment to avoid the escape of contaminants to the outside; b) suitably moistening the mass of shredded waste with water; c) placing and compacting a proper quantity of shredded and moistened waste in open-topped treatment containers which are transferred by conveying means into the subsequent processing phases; d) sealing closed each treatment container and connecting it with a microwave source of appropriate power, which heats the waste and moisture confined in said container in order to create steam and establish all those temperature, time and pressure conditions necessary to ensure sterilisation of said waste. In this phase, the internal pressure of the container is, if necessary, adjusted by controlled venting, in such a manner as not to exceed predetermined maximum values and, after this treatment phase, the container is conveniently depressuhsed and reopened; e) unloading the sterilised waste from the treatment containers, optionally cleaning said containers and reintroducing them into the operating cycle.

According to solutions protected by preceding patents in the name of the present

applicant, in order to limit the length of the sterilisation phase and to ensure uniform treatment of the microwave-irradiated material, the sterilisation container containing waste is conveniently internally depressuhsed when said container is closed by the sterilisation head, usually before the microwave generator is activated. This prior depressuhsation phase removes the air from the mass of waste to ensure that the treatment is uniformly distributed throughout the depth of the said waste and appreciably reduces the initial boiling temperature of the liquids present in the mass of waste to be treated, so reducing overall sterilisation cycle times.

For the purpose of transferring the containers into the subsequent different operating stations of the machine, the prior art mentions the use of carousel means or rectilinear transfer means, which have proved inappropriate for ensuring elevated operating efficiency of the machine. In the above-mentioned operating cycle, the station which occupies the longest operating time is the sterilisation station, which runs for times which are identical to or often greater than the sum of the times for the container loading phase and for the unloading phase of the sterilised material from said containers. The transfer means, after having taken a container from the sterilisation phase, carries it to the unloading station, then to the filling station and then returns the same container to the sterilisation station, which consequently remains inactive throughout the unloading and loading phases, as a result of which the magnetron of said station would be working in alternating manner and substantially at 50% of its capacity. In order to limit the time for which the magnetron is inactive, the prior art provides that, while one container is in the sterilisation phase of its associated contents, another container is in the loading phase and one in the unloading phase, such that, while one container is transferred from the sterilisation station to the unloading station, an already loaded container is transferred into the sterilisation station, while a container moves from the unloading station to the loading station. However, this solution only partially solves the problem because, once sterilisation has taken place, the container must be depressuhsed while still in connection with the sterilisation head, then must be extracted from the sterilisation

head, then a new container must reach the sterilisation station, must be coupled in a sealing manner to the sterilisation head, the proper vacuum values must be established in the container and finally, after all these periods of dead time, the magnetron is reactivated, and so continues to operate intermittently and certainly with very considerable dead time.

The object of the invention is to overcome these disadvantages of the prior art with an apparatus as defined in the appended claim 1 ) and subsequent dependent claims based on the following inventive concept.

The magnetron is connected to at least two sterilisation heads, by means of at least one waveguide and with changeover means which make it possible to connect said magnetron with one or the other of said heads. The container handling means, instead of being of the above-mentioned known type, comprise a robotic manipulator equipped with at least one gripper which, while the sterilisation station is active on a container which has previously been positioned on one of the heads thereof, arranges another container for filling and then positions it in the second sterilisation head, where the phase of establishing the vacuum in said container may be effected. Once sterilisation is complete and the container associated with the first sterilisation head has been depressurised, with the magnetron remaining active and the microwaves produced thereby being diverted to the second sterilisation head, the manipulator extracts the container from the first sterilisation head which is now inactive, transfers it to the unloading station, then to the loading station and finally repositions it under the first sterilisation head, awaiting the repetition of the described cycle which causes the magnetron to operate in substantially continuous manner, with the operational and productive advantages arising therefrom. In order fully to utilise the feed and unloading station operations, it is possible to provide that the single manipulator or a second manipulator operate on another two treatment containers which are subsequently brought together with another two sterilisation heads which are connected by means of a waveguide having changeover means to a

second microwave generator.

Further features of the invention and the advantages arising therefrom will be more obvious from the following description of a preferred embodiment thereof, illustrated by way of non-limiting example in the drawings of the attached plates, in which:

- Figure 1 is a schematic and plan view of the apparatus according to the invention;

- Figure 2 shows a schematic side elevation of details relating to the sterilisation station;

- Figures 3 and 4 show diagrams of possible operating cycles of the apparatus in question.

It may be seen from Figure 1 that the apparatus comprises a robotic manipulator with at least one gripper 1 of any kind suitable for holding the steel containers C1 , C2 according to the prior art, carried by a wrist 101 with means for rotation about a horizontal axis H and in turn mounted on a movement system with three orthogonal axes, for example with an arm 201 capable of sliding horizontally along its own longitudinal axis Y on a guide 301 supported by a slide 401 which slides on a guide 501 with a vertical axis Z and which is in turn mounted on a slide 601 orthogonal to said arm 201 and slidable on a guide 701 with a horizontal axis X. Displacements along the above-stated X, Y and Z axes are controlled by servo controls with high- precision electric motors and with electronic control of speed and phase, with two directions of rotation and optional brake, for example brushless motors. It will be understood that the system shown is one possible movement system of the gripper 1 and that other programmable robotic systems may be used for the purposes in question, which systems may also be systems with two or more orthogonal axes or systems with anthropomorphic robots or hybrid systems.

In order to ensure accuracy of relative positioning between the gripper 1 and the treatment containers C1 , C2, the latter may be equipped on the outside with optional recessed (or protruding) parts 10 which cooperate with optional corresponding protruding (or recessed) parts 11 of said gripper, which may be equipped with one or more sensors which may straightforwardly be implemented by persons skilled in the art and which automatically stop the operation of the apparatus in the event that said protruding and recessed parts are not correctly coupled together.

It may be seen from Figures 1 and 2 that the sterilisation station SS comprises two sterilisation heads 2, 2' arranged parallel to one another, with their microwave- emitting transparent part facing vertically downwards, equipped on the outside with the respective sealing gaskets 3, 3' and mounted one beside the other on a stationary support structure 4. It will be understood that, contrary to the illustration, the sealing means 3, 3' may be of the frontal type (see below), or of both the lateral and the frontal type. The upper end of the heads 2, 2' is connected to the two ends of a waveguide 5 of an inverted Y shape, the upper end of which is connected with the microwave generator 6 and, at the branching point thereof, has a changeover wall 7 pivoted at 107 and connected to an actuator 8 by means of which said wall may on command be brought into the position shown in Figure 2 with solid lines or into that shown with dashed lines, in order to connect the generator 6 to head 2 or head 2' respectively. Said heads are equipped with all the safety and control devices known from the prior art, in order to control pressure and temperature parameters in the containers C1 and C2 coupled thereto during the sterilisation phase of the waste located therein and to effect the prior phase of establishing the vacuum and the final phase of depressurising said containers, which devices are not taken into consideration because they are known and are not necessary to understanding the invention.

Each sterilisation head 2, 2' is associated at the bottom with a respective lifting device 9, 9' having an associated actuator, for example a screw and nut unit with an

electric drive motor or having a piston/cylinder unit, for holding containers C1 , C2 in cooperation with the associated heads 2, 2' in such a manner that said containers may be left behind in the sterilisation station by the handling gripper 1 which is consequently able to carry out other operations (see below). If needs be, the lifting devices 9, 9' may be such as to impart controlled and powered lifting and/or lowering movements to the sterilisation containers when such movements are not carried out by or are carried out not under the power of the gripper 1. The prior art teaches how the treatment containers C1 and C2 may be equipped at the bottom with downwardly open hook-like attachments A to cooperate with the mushroom heads 109, 109' of the lifting devices 9, 9' which, apart from lifting the containers C, are in this manner capable of extracting them with the necessary effort from the associated heads 2, 2'.

At the beginning of each operating cycle, containers C1 and C2 may be empty, engaged in the associated sterilisation heads 2, 2' and supported there by the respective lifting devices 9, 9', or one of them may be engaged in the respective head 2 or 2' while the other may be supported by the gripper 1 , or both of the containers may be deposited empty in a parking station indicated with a K in Figure 1 , equipped with reference means for correctly holding the containers by the gripper and equipped with sensors which indicate the presence or absence of said containers, this also enabling an operator to check the state of said containers in order, if necessary, to maintain or replace them. The apparatus functions with an operating cycle which will now be described with reference to Figures 1 , 2 and 3.

The gripper 1 takes a container C1 and positions it in station K1 where known means of any type operate which are capable of feeding a proper quantity of appropriately shredded, moistened and appropriately compressed material into said container.

During this phase, the container may advantageously be supported by means belonging to said station K1 , so as to ensure, especially during the phase of decoupling the container from the filling means, that particles of dirt do not fall onto the gripper, so soiling it. During this phase, the container may be handed over to

suitable temporary support means and vertical guides belonging to K1 and the small quantity of dirt which falls from the container during the filling phase may be collected by a box 21 (see below) which will be replaced periodically and placed in the shredder or may be collected by other suitable means. The container may be raised and lowered first for coupling with and subsequently for uncoupling from the unloading orifice of station K1 , by means of a lifting device of known type indicated 9 or 9' in Figure 2 for the sterilisation station, which cooperates with the lower attachment A of the treatment containers.

In the diagram of Figure 3, the crosshatched line portion indicated 12 indicates the loading phase of container C1 in station K1. Once loading is complete, the handling gripper 1 transfers the full container C1 beneath the head 2 where said container is lifted, engaged in said head and kept in association with the latter by the associated lower lifting device 9 (see Fig. 2). During this phase, the gripper 1 may rise in combination with the lifting device 9 or may itself carry out the phase of lifting and engaging the container in the head 2 and the lifting device 9 may be activated in a second phase to permit the gripper 1 to leave the container C1 behind and continue with the subsequent operating phase. While the material contained in C1 is firstly exposed to a vacuum and is then irradiated by the microwaves generated by the source 6, with the deflector blade 7 in the position shown in Figure 2 with solid lines, as is shown in Figure 3 by the line portion 13, the gripper 1 takes container C2 and turns it upside down in station K2 of Figure 1 for the unloading phase shown in Figure 3 by line portion 15, after which said gripper transfers the empty container C2 to station K1 for the loading phase shown in Figure 3 by line portion 16. In the unloading station K2, known means operate which, apart from mechanically assisting unloading of the material from the treatment container, may subject said container to adequate cleaning of the internal surface and of the orifice thereof which is subsequently intended to cooperate with the sealing means of the sterilisation head. In station K2, 20 denotes generic means for collecting and permitting the removal from the apparatus of the sterilised waste which is cyclically unloaded from the

treatment containers.

Once the container C2 is engaged in the head 2', while said head is preparing to establish the vacuum in C2, the gripper 1 moves over to hold container C1 to ensure that, at the end of the sterilisation phase 13, once the changeover wall 7 has moved into the position shown in Figure 2 with dashed lines and after the beginning of the sterilisation phase 17 of the material contained in C2 (Fig. 3), said gripper 1 gets ready to extract container C1 from the head 2, which container has previously been depressuhsed, and then carries said container into the unloading phase 14 (Fig. 3) in station K2 (Fig. 1 ), after which said gripper transfers container C1 to station K1 for the filling phase indicated with 12' in Figure 3, in order to repeat the described cycle. Once loading has finished, the gripper 1 transfers container C1 into the sterilisation station for coupling to the associated head 2, still before completion of the sterilisation phase 17 of the product placed in C2, such that the gripper 1 can then leave container C1 on head 2 and move on to C2 to carry out the subsequent unloading phase 18 (Fig. 3) and to repeat the described cycle, with the source 6 of Figure 2 operating continuously and being connected alternately with one or the other of heads 2, 2'. According to known solutions, the source 6 may be associated with means capable of detecting the intensity of the reflected wave and means will be provided to automatically attenuate said parameter to within safety values, for example by using the lifting devices 9, 9' to change the relative position of the mass of waste placed in the treatment containers and the associated sterilisation heads 2, 2' and/or by activating other control means effective for said purpose.

If cycle times permit, the machine is capable of operating according to the alternative cycle chart shown in Figure 4, according to which the sterilisation phases 17', 13 and 17, 13' carried out on containers C1 and C2 may be partially overlapped in the final part of one and the initial part of the other, with the source 6 of Figure 1 being temporarily connected with both containers C1 , C2, thanks the dividing wall 7 being temporarily located in a vertical position, before moving over into the other

interception position. It will nevertheless be understood that those cycles shown in Figure 3 and 4 merely exemplify some possible operating modes for the apparatus and that other cycle charts may be adopted without consequently going beyond the scope of protection of the invention.

As may be seen in Figure 1 , it is possible to provide, by the unloading station K2, an auxiliary unloading station K3 with a suitable container 19 in which is collected the material automatically unloaded with suitable means from one of the process containers C1 or C2, the contents of which has not been sterilised in accordance with the predefined parameters, for example due to excessive loading with metallic parts, and means will be provided to indicate the necessity for periodic replacement of the full container 19 with another empty container, while said full container is introduced into the shredder so that its contents mix with new material to be ground and may more readily be treated and disposed of with the latter. As an alternative to what has been described, the auxiliary station K3 may not be provided and the material which has not been correctly sterilised may be unloaded into container 21 of station K1 , which collects the material scattered during the loading phase and will itself be replaced periodically and introduced into the shredder. Instead of this container 21 , a hopper could be provided which discharges the product into a third service container which, at the end of the operating cycle is filled and introduced into the operating cycle of the apparatus, while one of the empty containers C1 or C2 may be positioned under said hopper.

The operational and economic advantages arising from the apparatus as described are obvious, which apparatus, apart from fully utilising the operation of the magnetron

6, now also exhibits the advantage of enabling the checking and maintenance of the components of the various operating stations, because the latter are located on the opposite side from that occupied by the robotic manipulator, which may itself also straightforwardly be inspected and optionally maintained. Unlike known systems, the apparatus also exhibits the advantage of being able to operate very rapidly because

only one container, which has limited inertia, is now moved at a time.

Structural and functional details of the loading, sterilisation and unloading stations have been omitted from the description, as have details of the cleaning stations of the container orifice on passage from the unloading station to the loading station and then on passage from the loading station to the sterilisation station, as well as details of the means for periodically cleaning the lower, transparent surface of the sterilisation heads 2, 2', because these are known and readily implementable by persons skilled in the art.

The scope of the invention also encompasses the design variant intended fully to utilise the operations of loading station K1 and unloading station K3, according to which one single manipulator 1 or a second manipulator acts on another two treatment containers which are subsequently brought together with another two sterilisation heads which are connected by means of a waveguide having changeover means to a second microwave generator. This variant has not been shown in the drawings because it is obvious and readily implementable by persons skilled in the art on the basis of the description alone.