Apparatus, method for sterilizing waste

Abstract

Method and apparatus (10) for sterilizing material comprising crushed waste, wherein the apparatus (10) comprises: a body (17) defining a sterilization chamber (V) extending along a development axis (X); a loading device (171) operable to open or close a loading opening (A) of the sterilization chamber (V); a movement assembly comprising at least one processing screw (172a, 172b) within the sterilization chamber (V); at least one discharge device (173) located in a discharge section along the development axis (X) and operable to open or close a discharge opening (B) of the sterilization chamber (V). A gap (I) is defined between the processing screw (172a, 172b) and an upper wall (P) of the body (17), extending at least partially along the processing screw (172a, 172b) and free from the latter to define a passage channel for material to be stirred by the processing screw (172a, 172b).

Description

[0001] APPARATUS, METHOD FOR STERI LIZI NG WASTE

[0002] The present invention concerns an apparatus and process for the method of sterilizing waste and, in particular, m edical and / or infectious waste. This innovative system offers a com plete solution for shredding and sterilizing waste, guaranteeing m axim um environmental safety and significant savings in space and resources.

[0003] Nowadays, a wide range of techniques and devices used to elim inate pathogens, m icroorganism s and harmful substances in both solid and liquid waste are generally known in the field of waste sterilization.

[0004] These techniques include incineration, autoclaving (i.e. high tem perature heat treatm ent in a sealed autoclave) , chem ical disinfection as well as the use of ionizing radiation or m icrowaves. However, the methodologies currently in use have various lim itations in term s of efficiency, energy consum ption, environmental im pact and safety of the personnel involved in the sterilization operation.

[0005] Som e m ethods m ay generate polluting em issions or require the use of hazardous chem icals, while others m ay not guarantee com plete sterilization of waste.

[0006] I n particular, a plant known today is based on a shredding process followed by a sterilization step.

[0007] After shredding, the waste undergoes a steam sterilization process that is designed to eliminate pathogens, making the waste sterile and safe for subsequent handling.

[0008] This system involves sterilization in a vertical autoclave with a funnel-shaped bottom from which a stirring screw extends upwards.

[0009] Today’s Applicant noted that this solution appears to be im provable in relation to the sterilization speed as well as in the sense of reducing the degree of moisture present in the sanitized waste.

[0010] The problem underlying the present invention is to im prove the waste sterilization treatm ent by solving the main problems com plained of in the prior art by means of a sterilization apparatus and method that enables waste, particularly infected waste, to be sanitized more efficiently.

[0011] As part of this task, it is the aim of the present invention to propose a sterilization apparatus and method that is industrially scalable, potentially automatable and economical.

[0012] Another aim of the present invention is to develop an apparatus and a sterilization method that allows for lighter and / or less wet sanitized waste than conventional solutions under the same operating conditions.

[0013] Yet another aim of the present invention is to provide a sterilization apparatus and method that im plies a smaller footprint than traditional solutions with the same waste treatment capacity.

[0014] This task, as well as these and other purposes that will better appear below, are achieved by a sterilization apparatus and method according to the appended independent claims.

[0015] Detailed characteristics of a sterilization apparatus and method according to the present solution are provided in the dependent claims.

[0016] Further features and advantages of the invention will become more apparent from the description of a preferred, but not exclusive embodiment of a sanitizing apparatus and method, illustrated in an indicative and non-lim iting em bodiment depicted in the accom panying tables of drawings, in which:

[0017] Figure 1 illustrates a simplified diagram of a sterilization apparatus according to the present solution;

[0018] Figures 2 and 3 illustrate respective schematic views of parts of a sterilization apparatus according to the present solution;

[0019] Figures 4a and 4b illustrate a body with sterilization com partment of a sterilization apparatus according to this solution in a side view;

[0020] Figure 5 shows a body with sterilization compartment of a sterilization apparatus according to the present solution in a front view;

[0021] Figure 6 shows an exam ple time diagram of the steps of a sterilization method according to the present solution.

[0022] With particular reference to the above-mentioned figures, a sterilization apparatus for material com prising shredded waste is referred to overall as 1 0.

[0023] The apparatus 10 may com prise a shredding assem bly 1 1 , which may com prise at least one shredder 1 1 a, itself traditional and not further described.

[0024] Specifically, in the exam ple in Figure 1 , shredding assem bly 1 1 com prises a single shredder 1 1 a, however, the number, size and, in general, the operating and dimensional parameters will be selected according to the contingent conditions of im plementation of the present solution.

[0025] The apparatus 10 can com prise at least one loading hopper 12 that can be placed on top of the shredder 1 1 a or, in general, the shredding assembly feeding the shredder 1 1 a with waste to be shredded.

[0026] The apparatus 10 may also com prise a first filtering assem bly 13 placed in aeraulic connection with the shredder 1 1 a and / or with the loading hopper 12 to keep them in slight depression, that is, at a degree of depression that makes it possible to avoid dispersion into the environment surrounding the apparatus 10 of any pathogenic agents contained in the waste that, in operation, is shredded by the shredder.

[0027] The shredding assem bly 1 1 can be mounted on a first frame 101 , possibly with the loading hopper 12 and the first filtering assem bly 13, so that they are supported independently of the rest of the apparatus 10.

[0028] The apparatus 10 may also com prise a feeding assem bly 14 which, in the exam ple of Figures 1 and 2, comprises a tiltable container 141 , capable of containing waste packages to be sanitized, lifting them to the hopper inlet and discharging them into the hopper.

[0029] The apparatus 10 may com prise a first lifting assem bly 15, e.g. lifters 151 , 152 preferably with augers, which is air-tightly connected to the shredding assem bly 1 1 to receive shredded waste from the latter.

[0030] The apparatus 10 may also com prise a transfer hopper 16 which is connected to first ones 151 of the lifters 151 , 152 (to receive shredded material from the shredding assem bly 1 1 ) and to second ones 152 of the lifters 151 , 152 (so that they remove shredded material from the transfer hopper 16.

[0031] Preferably the lifting assembly 15 comprises two second lifters 152 to form two sterilization lines (as further described below) in parallel for the benefit of the reliability of the productivity of the apparatus 10.

[0032] Clearly, without loss of generality, the im plementation of the present solution involving two sterilization lines is illustrative and not lim iting. Depending on the contingent im plementation of the present solution, there may be a single sterilization line or more than two sterilization lines.

[0033] According to an aspect of the present solution, the apparatus 10 may com prise at least one body 17 defining a sterilization com partment V extending along a development axis X and configured such that, when the sterilization apparatus is installed in place, the development axis X extends at least predom inantly horizontally. I n the exam ple of Figures 1 -3, the apparatus 10 has two bodies 17 which preferably are twins and which have preferably parallel axes of development X so as to form , with the corresponding second lifters 152, which feed them , two sterilization lines.

[0034] The apparatus 10 may com prise a loading device 171 operable to open or close a loading opening A provided in the body 17 and com m unicating with the sterilization com partment V.

[0035] Through the loading opening A the lifting assem bly 15 can introduce into each body 17 shredded waste to be sterilized.

[0036] The apparatus 10 may com prise a movement assem bly comprising at least one processing screw 172a, 172b housed within the sterilization cham ber V and positioned therein such that, upon its activation, material present in the sterilization cham ber V is conveyed along the development axis X.

[0037] The apparatus 10 may com prise at least one discharge device 173 located in a discharge section along the development axis X and operable to open or close a discharge opening B that com m unicates with the sterilization cham ber V; the processing screw 172a, 172b being positioned in the sterilization cham ber V such that it can be operated to push material towards the discharge opening B.

[0038] A gap I is defined between the processing screw 172a, 172b and an upper wall P of the body 17, in the sterilization cham ber V, extending at least partially along the processing screw 172a, 172b and free from the latter to define a passage channel for material to be stirred by the processing screw. The processing screw 172a, 172b can extend between the loading opening A and the discharge opening B.

[0039] The movement assembly can be selectively operated in either a mixing direction V1 or an expulsion direction V2, opposite to the mixing direction V1 .

[0040] The mixing direction V1 , exemplified in Figure 4a, has the at least one processing screw 172a, 172b which is operated to push towards the loading opening A material M which interferes with the at least one processing screw 172a, 172b.

[0041] I n this way, the com bined action of the movement Mi of the material M entering the sterilization com partment V and the action of each of the processing screws 172a, 172b causes the stirring Mr of the material M which, as will be better described below, first promotes sterilization of the material by contact with steam injected into the sterilization compartment V at an operating tem perature and, subsequently, dehumidification of the material M sanitized by the steam .

[0042] The expulsion direction V2, exem plified in Figure 4b, has the at least one processing screw 172a, 172b that can be operated to push the material M that interferes with it towards the discharge opening B.

[0043] Therefore, the movem ent assem bly can have the dual function of mixing the material M in such a way as to facilitate sterilization and treatment in general (e.g. also dehumidification) and promoting the expulsion of the material from the sterilization compartment V following treatm ent.

[0044] The movement assembly may com prise and preferably consist of two of said at least one processing screw 172a, 172b, for example as shown in Figure 5.

[0045] A first screw 172a of the two processing screws 172a, 172b extends according to a first helical direction and the second of the two screws extends according to a second helical direction where, preferably, the first screw 172a and the second screw ( 172b) 172b are positioned side by side and can have the first helical direction and the second helical direction opposite along the development axis X of the sterilization cham ber V so as to make stirring particularly effective when these rotate in the stirring direction V1 .

[0046] It is understood that, if the screws 172a, 172b have opposite helical directions, they are rotated in opposite directions to obtain the stirring direction V1 (or the expulsion direction V2) (as for exam ple shown in Figure 7) .

[0047] The sterilization com partment V may have a bottom F which, when the body 17 is in place, delimits it at the bottom .

[0048] The at least one processing screw 172a, 172b can be positioned in the sterilization com partment V so as to be superim posed on the bottom F and to skim it to prevent the formation of incrustations of material on it in operation. Thus, when the body 17 is in place, the gap I is provided above the at least one processing screw 172a, 172b.

[0049] The apparatus 10 may com prise injectors connected to the body 17 and arranged to inject steam into the sterilization compartment V to sterilize the material contained therein by thermal action.

[0050] I n this way, the apparatus 10 achieves sterilization heat treatment of the M material quickly, effectively and reliably thanks to the com bined mechanical stirring action Mr of the screws 172a, 172b and the thermal action of the steam . I n fact, precisely because of the continuous stirring of the material M induced by the action of the screws 172a, 172b, the contact of the material M is maxim ized in unit time, allowing the m inim ization of the sterilization time.

[0051] The apparatus 10 may com prise a second frame 102 to which each body 17 may be attached for support.

[0052] Preferably, the second frame 102 is separated from the first frame 101 so as to prevent or lim it a transm ission of vibrations generated by the shredder 1 1 a to each body 17.

[0053] The apparatus may com prise:

[0054] - a collection conveyor 103, preferably with screw conveyors with inverted helixes, onto which each discharge opening B faces;

[0055] - a transfer assembly 104 com municating with the collection conveyor 1 03 and configured to transfer sterilized material to a storage container 105.

[0056] The transfer assembly 104 may com prise a first conveyor 104a and a second conveyor 104b, preferably with two screws with inverted helixes, and a third conveyor 104c, e.g. horizontal, configured and positioned to transfer sterilized material from the first conveyor 104a to the second conveyor 104b which can discharge into the storage container 105.

[0057] On the second frame 102, the apparatus 10 may comprise a steam generating device 106, connected to each body 17 for injecting steam into the respective com partment V to sterilize the material contained therein, in operation.

[0058] According to another aspect, the present solution concerns a material sterilization method, an exam ple of which is shown in Figure 6 by way of non-limiting exam ple.

[0059] Such a method of sterilization of shredded waste may involve a step A of feeding waste into the sterilization compartment V of a sterilization apparatus 10.

[0060] I n particular, step A may involve introducing shredded material M into the sterilization com partment V through the loading opening A, opened by the loading device 171 .

[0061] Preferably, this introduction is carried out at the same time as the depressurization of the hopper 12 and / or the sterilization com partment V suitable to prevent dispersion of material, or any pathogens contained therein, into the environment in which the apparatus 10 is located.

[0062] The air sucked in to implement said depressurization is preferably treated by the first filtering assem bly 13 which may comprise a HEPA filter to filter the air before it is reintroduced into the environment.

[0063] I n order to im plement at least one of the aforementioned depressurizations, according to at least one aspect of the present solution, the apparatus 10 is preferably provided with a connection 18 to a suction assembly capable of generating a vacuum , for exam pie a vacuum pump.

[0064] The method according to the present solution may comprise a depressurization step B, of depressurizing the sterilization com partment V which may, for example, be functional for extracting dust and / or harmful substances and / or pathogens to be filtered; preferably, the air extracted from the sterilization com partment V by the depressurization of step B may be treated by the first filtering assem bly 13 which may comprise a HEPA filter to filter the air before it is reintroduced into the environment.

[0065] The method according to at least one aspect of the present solution may com prise a step C, of introducing steam into the sterilization chamber; preferably the steam introduced is superheated steam and may be introduced by means of at least one injector (and preferably a plurality of injectors) schematically shown in Figures 4a and 4b in 19.

[0066] The method according to at least one aspect of the present solution may com prise a step D, of stirring the waste by means of a drive of the movement assembly of the sterilization apparatus 10 to promote homogeneous contact of the waste with the steam for sterilization of the waste.

[0067] The method according to at least one aspect of the present solution may com prise a step E, subsequent to step B, of pressurisation of the sterilization com partment V.

[0068] Step E is preferably im plemented at the same time as step D and can coincide with the latter, i.e. - without loss of generality - the pressurization of step E can be achieved by the injection of steam - preferably at high pressure as exem plified below - of step D.

[0069] Steps E and / or D may include a step W, of holding or maintenance, during which the thermo-psychro-hygrometric conditions are substantially kept constant for a holding time which is selected according to the contingent conditions of im plementation of the present solution and which preferably decreases as the operating tem perature increases and the operating pressure inside the sterilization com partment V which is maintained during the holding time.

[0070] The holding time can, for exam ple, be selected by testing for pathogens or harmful substances following application of the method according to the present solution. I n particular, the holding tim e can be selected in such a way that the presence of pathogens or harmful substances has been abated above a chosen tolerance threshold or that this presence is substantially negligible or, in any case, com plies with any national or international regulations on the sterilization of infected or contam inated waste.

[0071] For exam ple, the holding time can be between 5 m in and 7 m in when the inside of the sterilization compartment V (and the material M contained therein) is at a tem perature between 140°C and 145°C and preferably substantially and 142°C, and at a pressure between 3.5 bar and 4 bar and preferably 3.8 bar.

[0072] The method according to at least one aspect of the present solution may com prise a step F, subsequent to step E, of depressurizing the sterilization com partment V, e.g. in order to bring the material M, which is kept there in operation, to am bient conditions.

[0073] The method according to at least one aspect of the present solution may com prise a step G, of cooling the waste in the sterilization com partment V, e.g. to bring the material M, which is kept there in operation, to am bient conditions.

[0074] The method according to at least one aspect of the present solution may com prise a step H, following step C, of dehumidifying the waste present in the sterilization compartment V.

[0075] Preferably, steps F and / or G and / or H can at least partially contextualise and preferably form a single operational step, in order to achieve the dehum idification and drying of the material M. I n fact, in at least one of these steps F and / or G and / or H preferably ambient gas is drawn from the sterilization com partment V and moisture is extracted from it, e.g. , by means of at least one water-water and / or water-air heat exchanger in order to cause condensation of the steam present in the gas.

[0076] I n accordance with at least one aspect of the present solution, the condensed vapour forms an eluate that is sanitized and can therefore be discharged or sent to a wastewater treatment plant.

[0077] The method according to at least one aspect of the present solution may com prise a step J, following step D, of discharging the waste from the sterilization com partment V by action of the movement assembly.

[0078] Such dehum idification / drying of the material M has the significant advantage of greatly reducing the mass of sanitized waste that the apparatus 10 and the method, according to at least one aspect of the present solution, achieve.

[0079] It is understood that the steam injection step C is substantially subsequent to and separate from step B in order to avoid, or minim ize the effect that, steam injected in step C is sucked out of the sterilization com partment V by depressurization means operated in step B.

[0080] The depressurization of the sterilization compartment V of step B can be functional to promoting the input of steam into the sterilization com partment V during step C.

[0081] Step C, of injecting steam , may involve at least one of the following sub-steps:

[0082] - a sub-step C1 , of pressurizing the sterilization compartment V at an operating pressure substantially comprised between 3 bar and 4 bar;

[0083] - a sub-step C2 of heating to an operating temperature substantially comprised between 130°C and 150°C.

[0084] Sub-step C1 and sub-step C2 can at least partly be im plemented simultaneously and, preferably, during step C, material M contained in the sterilization com partment V is maintained at the operating pressure and tem perature for an operating time of at least 5 m in and preferably not less than 7 m in.

[0085] The sterilization method according to at least one aspect of the present solution may have the stirring step D im plemented at least in part during at least one of: step A and / or step B and / or step C and / or step E and / or step F and / or step G and / or step H.

[0086] For exam ple, without loss of generality, in the em bodiment exemplified in Figure 6, the stirring step D is im plemented during the waste input step A, to promote homogenization of the material M to be sterilized and to prevent it from packing on the bottom F.

[0087] Step D can also be im plemented during steps B and C and E to optimize the contact of the material M with the functional steam and in general the sterilization action by heating and pressurization of the m aterial M to be sterilized.

[0088] The stirring step D can be im plemented at the same time as steps Fm G and H to promote effective and fast dehumidification and cooling of the material M for optim ized drying.

[0089] Step D can involve operating the movement assem bly according to the stirring direction V1 .

[0090] The method according to at least one aspect of the present solution may have step H performed at least partially during at least one of step F and step G, which may be im plemented at least partially simultaneously. Step H can be im plemented at least partly by means of a condenser assem bly to remove moisture from am bient gas sucked in from the sterilization compartment V by condensation, to remove moisture present in the sterilization com partment.

[0091] I n accordance with at least one aspect of the present solution, the apparatus 10 com prises a front support 174 supporting one end of the screws 172a, 172b being, at the other end connected -by means of a sealed connection for crossing the body 17- to a transmission 175 kinematically connecting them to at least one motor 176 for their controlled drive in accordance with the method according to at least one aspect of the present solution.

[0092] Therefore, it can be understood how the present solution achieves the task and purposes.

[0093] I n particular, operational tests have shown that a sterilization apparatus and a sterilization method according to the present solution allow for high productivity in obtaining dried shredded waste, preventing the dispersion of harmful or pathogenic substances into the environment through air or elutions.

[0094] Thus, the sterilization treatm ent of waste is greatly im proved, solving the main problems com plained of in the prior art.

[0095] A sterilization apparatus according to at least one of the aspects of the present solution is easily industrially scalable, highly automatable and economical.

[0096] A sterilization apparatus and method according to the present solution also makes it possible to obtain, under the same operating conditions, sanitized waste that is lighter and / or less moist than traditional solutions and / or that has less bulk compared to traditional solutions with the same volume of waste to be treated.

Claims

CLAI MS1 . An apparatus (10) for sterilizing material including shredded waste, com prising:- a body (1 7) defining a sterilization chamber (V) extending along a development axis (X) and configured such that, when the sterilization apparatus ( 10) is in operation, the development axis (X) extends at least predom inantly horizontally;- a loading device (171 ) operable to open or close a loading opening (A) provided in the body ( 17) and comm unicating with the sterilization cham ber (V) ;- a movement assembly com prising at least one processing screw (172a, 172b) housed within the sterilization cham ber (V) and positioned therein such that, upon its activation, material present in the sterilization cham ber (V) is conveyed along the development axis (X) ;- at least one discharge device ( 173) located in a discharge section along the development axis (X) and operable to open or close a discharge opening (B) that comm unicates with the sterilization chamber (V) ; wherein the processing screw ( 172a, 172b) is positioned in the sterilization cham ber (V) such that it can be operated to push material towards the discharge opening (B) ; wherein a gap (I) is defined between the processing screw ( 172a, 172b) and an upper wall (P) of the body (17) in the sterilizationchamber (V), extending at least partially along the processing screw (172a, 172b) and free from the processing screw ( 172a, 172b) to define a passage channel for material to be stirred by the processing screw ( 1 72a, 172b) .

2. Sterilization Apparatus (10) according to Claim 1 wherein the processing screw (172a, 172b) extends between the loading opening (A) and the discharge opening (B) and the movement assembly is selectively operable:- in a mixing direction (V1 ) , wherein the at least one processing screw (172a, 172b) is operated to push material that interferes with the at least one processing screw ( 172a, 172b) towards the loading opening (A) ; or- in an expulsion direction (V2) , opposite to the m ixing direction (V1 ) , wherein the at least one processing screw ( 172a, 172b) is operated to push material that interferes with the at least one processing screw (172a, 172b) towards the discharge opening (B) .

3. Sterilization Apparatus (10) according to any of the preceding claim s wherein the movement assem bly comprises two of the said at least one processing screw ( 172a, 172b) ; a first screw (172a) of the two processing screws ( 172a, 172b) extends according to a first helical direction and the second of the two processing screws (172a, 172b) extends according to a second helical direction, the first screw ( 172a) and the second screw( 172b) are positioned side by side and, preferably, the first helicaldirection and the second helical direction are opposite along the development axis (X) of the sterilization cham ber (V) .

4. Sterilization Apparatus (10) according to any of the preceding claims wherein the sterilization cham ber (V) has a bottom (F) which, when the body ( 17) is in operation, delimits it inferiorly; the at least one processing screw ( 172a, 172b) is positioned in the sterilization cham ber (V) so as to be superim posed on the bottom (F) and to skim it to prevent the formation of incrustations of material on it; the gap ( I) being provided above the said at least one processing screw ( 172a, 172b) , when the body ( 17) is in operation.

5. Sterilization Apparatus (10) according to any of the preceding claim s com prising injectors connected to the body ( 17) and arranged to inject steam into the sterilization cham ber (V) to sterilize the material contained therein.

6. A method for sterilizing material including shredded waste, com prising:- a step A, of introducing waste into the sterilization cham ber (V) of a sterilization apparatus ( 10) according to any of claim s 1 -5;- a step B, of depressurizing the sterilization cham ber (V) ;- a step C, of introducing steam into the sterilization chamber;- a step D, of stirring the waste by actuating the movement assembly of the sterilization apparatus (10) to promote homogeneous contact of the waste with the steam forsterilizing the waste;- a step E, subsequent to step B, of pressurizing the sterilization cham ber (V) ;- a step F, subsequent to step E, of depressurizing the sterilization cham ber (V) ;- a step G, of cooling the waste present in the sterilization chamber (V) ;- a step H, subsequent to step C, of dehum idifying the waste present in the sterilization chamber (V);- a step J, subsequent to step D, of discharging the waste from the sterilization cham ber (V) by means of the movement assembly.

7. Sterilization Method according to Claim 6 wherein step C, of introducing steam , follows step B and is separated from it to prevent steam introduced in step C from being drawn out of the sterilization cham ber (V) by depressurization means activated in step B; wherein the depressurization generated in the sterilization chamber (V) promotes the ingress of steam into the sterilization chamber (V) during step C.

8. Method according to one of claims 6- 10 wherein step C, of introducing steam , com prises- a sub-step C1 , of pressurizing the sterilization cham ber (V) to an operating pressure substantially between 3 bar and 4 bar;- a sub-step C2 of heating to an operating temperature substantially between 130°C and 150°C;wherein sub-step C1 and sub-step C2 can be at least partially carried out sim ultaneously and, preferably, during step C material (M) contained in the sterilization cham ber (V) is maintained at the operating pressure and operating tem perature for an operational tim e of at least not less than 5 m inutes and preferably not less than 7 m inutes.

9. Sterilization Method according to any of claims 6-8 wherein step D of stirring is carried out at least in part during at least one of: step A and / or step B and / or step C and / or step E and / or step F and / or step G and / or step H.

10. Method according to the preceding claim wherein step D com prises actuating the movement assem bly in the m ixing direction (V1 ) of claim 2.1 1 . Method according to any of claims 6- 10 wherein step H is carried out at least partially during at least one of step F and step G which can be carried out at least in part sim ultaneously; wherein step H can be carried out at least in part by a condenser assembly configured to remove moisture from the inside of the sterilization cham ber (V) by condensing steam present in the sterilization chamber (V) .

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