WO2013075162A1

WO2013075162A1 - Waste treatment apparatus and method

Info

Publication number: WO2013075162A1
Application number: PCT/AU2012/001110
Authority: WO
Inventors: Paul WOODFORD; Adalbert DROMBLIKOVIC
Original assignee: Medivac Technology Pty Limited
Priority date: 2011-11-21
Filing date: 2012-09-17
Publication date: 2013-05-30
Also published as: AU2012343320A1

Abstract

A waste treatment apparatus (10) comprised of hopper (12) with inlet (68) and lid (52), a shredder (14). The shredder (14) transfers the shredded waste into a first treatment auger (16) and subsequently to a second treatment auger (18). The screw in the second treatment auger is bi-directional and has two outlets, the first outlet, the auger hopper outlet (122) returns shredded waste into the hopper (12). The second outlet of the second treatment auger (18) is gate (20) where treated shredded waste exits after sterilisation. Depending on which direction the second transfer and treatment auger (18) is operating, the shredded waste is either transferred back into the hopper (12) of the apparatus for further treatment, or is ejected at the gate (20). Hopper (12), shredder casing (44) and first and second transport and treatment augers (16 and 18) together define a pressure vessel (72). Steam jackets (124) are applied around the pressure vessel (72).

Description

WASTE TREATMENT APPARATUS AND METHOD

TECHNICAL FIELD

The invention relates to the treatment of waste that is contaminated or in need of sterilisation, such as waste generated by medical facilities including hospitals. However, it will be appreciated that the invention is not limited thereto and can be applied to any stream of waste such as organic matter and/or general waste.

BACKGROUND ART

The following discussion of the background to the invention is intended to facilitate and understanding of the invention. However it should be

appreciated that discussion is not an acknowledgement or an admission that any of the material references was known to or part of the common general knowledge of the skilled addressee.

Hospitals and other medical facilities generate large amounts of infectious waste that ordinarily needs to be transported to specialised facilities for disposal. In most cases the specialised facilities utilise incineration or chemicals to sterilise the contents of the containers. Commonly, the only waste disposal apparatus present in hospitals are large autoclave units that only sterilise waste streams, and do not reduce the volume of waste .

Specialised on-site shredding and sterilising apparatus have been proposed to overcome this problem. However such devices are comprised of many moving parts including shredding and cutting mechanisms that are prone to break down. Also, the size and shape of the machines made them very difficult to service resulting in downtime and the consequent build up of potentially dangerous medical waste. Other disadvantages of prior art shredders or autoclaves include high environmental costs, including high energy consumed to run the devices per cubic metre of waste treated and the large footprints they occupy.

DISCLOSURE OF INVENTION

In a first embodiment of the invention, a pressurised waste treatment apparatus is provided, comprising:

i. a hopper having a resealable inlet for receiving waste to be treated;

ii. a shredder in communication with the hopper which is

comprised of at least two counter rotating shafts set at an angle on which are mounted a plurality of spaced apart shredder blades, the blades being so arranged on each shaft so as to be between the blades on the other shaft and, wherein, when the shafts are contra rotated with the top portions of the blades moving towards each other they draw the received waste into and through an outlet of the shredder; and

iii. means for transferring the shredded waste from the outlet of the shredder back into the hopper;

iv. steam generation and distribution means adapted to supply sufficient steam and pressure to sterilise the waste to be treated in at least the hopper and shredder;

v. means for ejecting the shredded waste post treatment from the apparatus.

Preferably the means for transferring the shredded waste from the outlet of the shredder back into the hopper is provided by: a. a first transfer and treatment auger in communication with the outlet of the shredder which receives shredded waste and agitates it as it raises it simultaneously to its outlet; b. a second transfer and treatment auger which has an inlet in

communication with the outlet of the first transfer and treatment auger, and where the second transfer and treatment auger is bi directional and has two outlets, either side of its inlet, wherein the first outlet is in communication with the hopper, and wherein the second outlet is fitted with a gate for discharging treated and shredded waste.

Preferably the resealable inlet is comprised of a hopper inlet and a lid and wherein the resealable inlet incorporates a mechanism that prevents the hopper lid fully opening under pressure but which allows the hopper lid to partially open under pressure, thereby allowing the pressure vessel to vent its contents without the lid opening explosively.

Preferably, the gate of the second transfer and treatment auger is a hydraulically operated ball valve incorporating a seal and scraper that are adapted to clean the surface of the ball as it is rotated so as to prevent the valve from becoming jammed.

Still more preferably, the hopper and shredder, first treatment and transfer auger, and second treatment and transfer auger are mounted in a frame.

Preferably, the frame is comprised of at least two pivotally connected sub frames mounted on wheels wherein the frame is able to be pivoted open to allow access by a person to the components of the apparatus.

According to a second embodiment of the invention, waste treatment apparatus further comprises any one or more of the following: a. receptacle tipping mechanism for lifting, tipping and emptying receptacles containing waste into the resealable inlet of the hopper.

b. RFID sensor that is adapted to read RFID tags present on the receptacles and wherein the information read from the RFID tag is sent to a PLC unit.

c. electronic scales for weighing the receptacle and wherein the weight of the receptacle is sent to the PLC, along with any RFID data.

d. controls for the apparatus that are operated remotely from the apparatus, where control signals are sent to the device either wirelessly or by using a wired connection.

According to a further aspect of the invention there is provided a methodreating waste using the apparatus of the first aspect:

a. heating the components of the apparatus;

b. loading the combined hopper/shredder with waste to be treated via the inlet;

c. extracting the air from the apparatus using a vacuum pump 76, of the apparatus;

d. injecting steam into the apparatus until the temperature and pressure are high enough for sterilisation;

e. activating the shredder;

f. pulling the waste through the shredder into the first treatment and

transfer auger and, thereafter, into the second treatment and transfer auger which is set to deliver the contents of the auger back to the combined hopper/shredder; g. repeating the above step until the sterilisation and shredding process is complete;

h. extracting the steam from the apparatus and condensing it back to liquid water;

i. cycling the shredded and sterilised waste in a vacuum through the

shredder, first treatment and transfer auger and, thereafter, into the second treatment and transfer auger so as to dry the shredded and sterilised waste; and

j. opening the outlet gate and reversing the direction of the second

treatment and transfer auger so that the shredded and sterilised waste exits the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of a waste treatment apparatus according to a first embodiment of the invention;

Fig. 2 is a side view of the waste treatment apparatus of Fig. 1

Fig. 3 is a further side view of the waste treatment apparatus of Fig. 1 Fig. 4 is a cross sectional side view taken along line A-A of Fig. 3 Fig. 5 is a top plan view of the waste treatment apparatus of Fig. 1 Fig. 6 is a top plan view of the waste treatment apparatus of Fig 1 in which the sub frames have been opened for access to the interior of the apparatus

Fig. 7 is a perspective view of the opened apparatus of Fig. 6

Fig. 8 is a cross sectional view of the shredder of the apparatus shown in Fig. 1

Fig. 9 is an enlarged view of one end of the shaft shown in Fig. 8.

Fig. 10 is cross section view of an activated pressure seal of Fig 9 Fig. 11 is an exploded view of the secondary seals and associated components of Fig. 9

Fig. 12 is a cross section view of the auger shaft seal arrangement for the augers shown in Fig.1

Fig. 13 is a perspective view of the inlet and lid of Fig. 1

Fig. 14 is a top view of the hopper inlet, lid and locking mechanism of the apparatus shown in Fig. 1

Fig 15 is a side cross sectional view of the hopper inlet, lid and locking mechanism of the apparatus shown in Fig. 14 in a locked state Fig. 16 is a side cross sectional view of the hopper inlet, lid and locking mechanism of the apparatus shown in Fig. 14 in an unlocked state

Fig. 17 is a close up view of the teeth of the lid locking rim and the inlet rim of the hopper inlet, lid and locking mechanism of the apparatus shown in Fig. 14 and Fig. 15

Fig. 18 is a perspective view of the steam generation circuits, of the first embodiment of the invention

Fig. 19 is a schematic showing the treatment zones of the waste

treatment apparatus shown in Fig. 1

Fig. 20 is a perspective view of a fully assembled waste treatment

apparatus according to a second embodiment where a bin tipper, user platform and control panel are incorporated

Fig. 21 is a perspective view of the apparatus from Fig. 20 shown in its open state

Fig. 22 is a enlarged view of the circled portion B from Fig. 21 in which a castor or wheel of the sub frame is shown in detail.

Fig. 23 is a schematic of the shredder drive train of Fig. 1 Fig. 24 is an exploded view of an auger of the apparatus shown in Fig. 1 Fig. 25 is a cross section view of the ball valve of the transfer gate

shown in Fig. 2

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention provides a fully enclosed and automated system to sterilise medical waste, reduce its volume, and render its components unrecognisable. The final treated waste is harmless and safe to dispose of as ordinary municipal waste. The invention uses a mechanical cutting device contained within a pressurised steel containment system, such that pressure and steam, combined with the effect of the cutting device, is able to achieve the desired level of sterilisation and rendering of the treated waste harmless.

Shown in Figs. 1 to 7 is a waste treatment apparatus 10 which is comprised of a number of components, including a hopper 12 incorporating a shredder 14 at the bottom of the hopper 12. The hopper 12 is substantially cylindrical and has a hopper inlet 68 and a hopper lid 52 that is adapted to seal the hopper inlet 68. The hopper 12 is adapted to be able to receive one 240L bin or two 120L bin's worth of waste. The shredder 14 communicates shredded waste into a first transfer and treatment auger 16 and subsequently to a second transfer and treatment auger 18. The screw in the second transfer and treatment auger is bi-directional and has two outlets, the first outlet , the auger hopper outlet 122 returns shredded waste into the hopper 12, above the shredder 14 such that shredded waste is passed through the shredder 14 again. The second outlet of the second transfer and treatment auger 18 is gate 20 where treated shredded waste exits the apparatus after the sterilisation and shredding cycle has completed. The first transfer and treatment auger 16 delivers shredded waste to a point between the two outlets such that the depending on which direction the second transfer and treatment auger 18 is operating, the shredded waste is either transferred back into the hopper 12 of the apparatus for further treatment, or is ejected from the apparatus at the gate 20.

The simultaneous shredding, sterilisation and recirculation of shredded waste through the apparatus 10 is an important feature as it allows for the rapid transformation of waste into a harmless, inert, granular and

unrecognisable waste stream that can be placed into the general waste stream of a hospital or other medical facility, thereby obviating the risks associated with the transport of hazardous medical waste.

Hopper 12, shredder casing 44 and first and second transport and treatment augers 16 and 18 are manufactured from high grade stainless steel (preferably stainless steel grade 316) and together define a pressure vessel 72 in which steam is introduced at pressure. Shown in Fig. 19 are the components shown in a simplified schematic cross section where it can be seen that steam and pressure are distributed throughout the components to define a treatment zone 80. Steam is introduced into the treatment zone 80 by way of steam inlet valves 101 , and removed by way of steam waste valves (not shown).

By circulating the waste through the components and under the constant influence of pressure and high temperature, the waste is rapidly rendered inert and unrecognisable. Steam jackets 124 are applied around the pressure vessel 72. The steam jackets 124 have steam introduced via steam jacket inlet lines 126. The steam jackets 124 are incorporated to pre-heat the pressure vessel before it is required to operate and also while it is running to maintain constant temperature and pressure in the treatment zone 80. Steam jackets 124 cover 50% of the pressure vessel 72. Surrounding the steam jackets 124 and any part of the pressure vessel 72 that is not covered by steam jacket are layers of insulation which have been applied to prevent the escape of heat energy (not shown).

Referring to Fig.4 (a cross section taken along line A-A of Fig. 3), Fig. 8, and Fig. 23, various subcomponents of shredder 14 can be seen. From Fig. 23 it can be seen that there are a pair of shredder shafts 22 upon which are mounted a plurality of shredder blades 46. Shredder blades 46 in turn, feature a plurality of cutting teeth 132. In normal operation the shafts are contra-rotated such that the teeth converge, thereby gripping the waste and pulling it down into the shredder 14. The shredder shafts 22 are driven in a contra-rotating manner by shredder gears 130 which are in turn driven by the shredder drive gear 128 which is driven by the shredder drive 32. The shredder drive 32 is in turn driven by the shredder motor 33.

Shredder shafts 22 are mounted in bearing housings 24 which contain bearing 23 as shown in Figs. 4 and 8. Fig. 9 is a close up cross section view of a shredder shaft end 22 mounted in the bearing housing 24. As can be seen in the diagram, an airtight seal is maintained around the shredder shaft 22 and shredder casing 44 by way of multiple seals. The invention uses multiple seals to prevent the escape of sterilising steam, and the prevention of ingress of shredded matter and any liquids present in the apparatus from entering the bearing causing it to seize and require maintenance. The primary seal 26 forms a pressure and vacuum barrier between three components, firstly the primary seal ring 136 mounted on the shredder shaft 22, the labyrinth 146 which is mounted internally to the shredder casing 44 on the shredder shaft 22 and the bearing housing 24 which is mounted on the shredder shaft on the outside of the shredder casing 44.

The secondary seals 28 perform the main function of sealing the steam pressure in the treatment zone 80. As shown in Fig. 11 , the secondary seals 28 are in the present embodiment, comprised of three separate seals, a barrier seal 140, an activated pressure seal 142, and a vacuum seal 138. The secondary seals 28 extend around seal bush 134 which presses against primary seal ring 136 and O ring 144 that extends in between. The first barrier seal 140 provides protection against the ingress of material to the activated pressure seal 142 which is shown in Fig 10. The activated pressure seal features a pressure seal O ring 148 which activates the seal in the absence of any steam pressure or vacuum. The third seal is the vacuum seal 138 which operates to prevent the ingress of air during the vacuum sequences.

A similar arrangement of seals can be found in respect of the first and second treatment augers 16 and 18 where the auger shaft 150 extend to the auger motors 30 which are located on the outside of the treatment zone 80. Referring to Fig. 12, a cross section of the auger bearing housing assembly 160 is shown which is comprised of a number of components. Firstly there is an auger shaft 150 which has mounted on it, the auger end cup body 154. The auger end cup body 154 and the auger shaft 150 have intermating keys and slots which cause the two components to move together in the auger bearing housing assembly 160. The two components are also sealed together by way of the cup body O-ring 162 which prevents steam and waste from entering into the space between the auger shaft 150 and auger end cup body 154. The auger end cup body 154 receives the auger bearing housing 156 which is fixed to the auger flange plate 174 and therefore does not move with the auger shaft 150 of auger end cup body 154. Together, the auger shaft 150, auger end cup body 154 and auger bearing housing 156 comprise the auger bearing housing assembly 160 which is mounted within the body of the auger barrel 158 via the auger flange plate 174. The primary face seal 164 is the first barrier which prevents solid waste entering into the space between the auger bearing housing 156 and auger end cup body 154. A second barrier is provided in the form of auger guide rings 166, which act as both a mechanical barrier and bushes. Similar to the shredder secondary seals 26, there are in the first and second treatment augers 16 and 18, a first auger barrier seal 168, an activated auger pressure seal 170 and finally, an auger vacuum seal 172. After the secondary seals there are two sets of auger bearings 152. The two sets of bearings are used to provide support for the longitudinal auger shaft 150.

In order to further minimise the potential for the ingress of shredded material into shredder drive 32, shredder motor 33 and associated gears 128 and 130, and into auger motors 30, the motors and drive components have been raised such that fine detritus does not accumulate at the seals which separate the drives from the treatment zone 80 of the apparatus. This can be seen with respect to the shredder drive 32 which is elevated by virtue of the placement of the shredder on an angle. Further in the case of the auger motors 30, in both cases the shredded waste transported by the augers does not travel to the ends of the augers and accumulate where the auger motors 30 are located as they have outlets in the path of travel that prevent such

accumulation from occurring.

With respect to the angled shredder 14, it has been found surprisingly that the action of gravity and the shape of the hopper 12 allows medical waste receptacles such as sharps cont ainers from bouncing on the surface of the shredder blades 46 and not being caught by them which was a problem associated with prior art waste treatment devices. Under the action of gravity, such receptacles find themselves located and partially wedged by the curved wall of the hopper 12 and the lower end of the shredder 14 whereupon they are more easily grabbed by the shredder blade teeth 132 and pulled through the shredder 14. Referring to Fig. 25 the transfer gate 20 is comprised of a ball valve 178 which is associated with a seal 180 and integrated scraper 182. As the ball is rotated to reveal an exit aperture in the ball, the scraper 182 first scrapes off any accumulated shredded waste so that it does not get accumulated in between the ball valve 178 and the inside of the transfer gate 20.

There are two independent steam circuits in the apparatus 10. The first circuit provides the steam used to generate pressure and sterilise shredded waste within the treatment zone 80. The steam for this purpose is generated by boiler 102 as depicted in Fig. 18. In alternate embodiments of the invention, the steam may be provided by to the apparatus by way of a steam inlet line thereby obviating the need for the boiler. The boiler 102 receives water from the water tank 106 and thereafter delivers it into the treatment zone 80 via the steam inlet valves 101. Upon the completion of the sterilisation and shredding cycle the steam from the treatment zone 80 is collected through waste steam valves (not shown) and condensed by heat exchanger 78 and collected in a blow down tank 104 for subsequent disposal. In an average cycle, less than 2.5L of water is used in this manner. Steam from the steam jacket 124 is derived by boiling water from water tank 106 in the boiler 102 for delivery via steam jacket inlet lines 126. This water is completely recycled and not disposed of. Shown in Fig 5 is a top view of the components as shown in Fig. 18. An additional component is shown in this figure namely, the provision of a boiler dosing chemical tank 108 for dosing the boiler with chemical substances that prevent or inhibit corrosion. Such chemicals include tannins.

As shown in Fig. 5 to 7, the apparatus 10 contains a hydraulic system for providing motive power to the various auger motors 30 and shredder motor 33. The hydraulic system includes hydraulic reservoir 110, hydraulic pump 112, and a hydraulic fluid cooling assembly 114. The apparatus contains a mechanical safety mechanism for preventing the opening of the hopper lid 52 under pressure. It is described as mechanical as it still operates even if the electronic components of the apparatus fail. The manner in which this is achieved is best described by reference to Figs. 13 to 17. As can be seen in Fig. 13 and Figs. 15 and 16 the hopper inlet ring 68 features rim teeth 74. Hopper lid 52 is pivotally mounted by way of a lid arm pivot 58. In addition to pivoting away from the hopper inlet ring 68 the lid is capable of pivoting axially by virtue of lid pivot 56. As best seen in Fig. 13, the hopper lid 52 has a lid locking ring 62 around its periphery where the lid locking ring 62 further comprises lid locking teeth 64. The hopper lid 52 also features a resilient double lipped seal 60 which comes into contact with the hopper inlet ring 68 and forms an airtight seal that is capable of resisting pressure and vacuum by virtue of its double lips (not shown). Fig. 15 is a cross section of the inlet assembly in a locked state. Fig 16 shows a cross section of the inlet assembly in an unlocked state.

To close the assembly, the hopper lid 52 pivots down in a way that the lid locking teeth 64 pass by the rim teeth 74 and stop at a position below the rim teeth 74. Then the lid closure cylinder 54 causes the rim lid 52 (and associated rim teeth 74) to rotate such that the lid locking teeth 64 locate under the rim teeth 74. The axial movement is represented pictorially in Fig. 14 by angle or arc 118. After the hopper lid 52 is rotated into a locked position, the treatment of inserted waste can commence. After the process has completed, and to prevent the treatment zone 80 from opening under pressure, a mechanical safety pressure release mechanism is incorporated into the apparatus 10 by way of introducing a step 70 into the lid locking teeth 64 at the edge of the lid locking teeth that is last to emerge from under the rim teeth 74. If there was any residual pressure within the treatment zone 80 when the hopper lid 52 is opened, it would be vented safely whilst the hopper lid 52 remains "locked" by the engagement of the rim teeth 74 by the lid locking teeth 64. It achieves this under pressure as the lid locking teeth 64 are pressed upwards by the pressure within treatment zone 80. During the opening process, the two sets of teeth move apart from each other until a point is reached where the rim teeth 74 only contact the step 70 portion of the lid locking teeth 64. As the profile of the step 70 is lower than that of the remainder of the lid locking teeth 64, the pressure within the treatment zone 80 forces the hopper lid up by the depth of the step 70. This small movement allows the seal 60 to open slightly which allows the escape of steam pressure, whilst the hopper lid 52 is still firmly held in place by the rim teeth 74 and the step 70 of the lid locking teeth 64. This allows the steam pressure to be released from the treatment zone 80 without the hopper lid 52 opening explosively.

As depicted in Fig. 24, the first and second transport and treatment augers 16 and 18 contain two auger screws 50 each joined in their centre by auger screw couplings 48. The provision of an assembly of auger screws allows a degree of flexibility when servicing the apparatus as the shorter auger screws can be more easily removed, manoeuvred and transported if necessary. The auger screws are made from stainless steel. The rotation of the screws ensures that the shredded contents of the auger are constantly turned over providing good contact between the hot surface of the screw and the walls of the first and second augers 16 and 18. The agitation of the shredded material provided by the auger screws 50 is a significant contributor to the ability of the apparatus 10 to sterilise and render harmless the shredded waste introduced into the apparatus, in a short period of time.

The components of apparatus 10 are contained within three sub-frames which are pivotally connected to each other, such that the apparatus 10 can be opened up for maintenance. This can be seen in Figs. 6 and 7 where a first sub frame 34, a second sub-frame 36 and a third sub frame 38 are shown containing the components described above. In Fig 22, frame castors 40 are shown. Sub frames can be pivoted by using the castors which allow for the smooth movement of the frame. Alternatively the apparatus 10 can be moved by forklift by virtue of the frame tyne channels 42 that are incorporated under the subframe.

Figs 20 and 21 show the finally assembled apparatus 10 according to a second embodiment of the invention wherein the apparatus 10 further comprises a hopper 12, loading device 84 which is used to lift waste and place it in the hopper inlet 68. The hopper loading device also comprises load scales 90 for weighing the receptacle containing the waste to be treated, and a RFID reader 92 which reads embedded RFID tags which are contained within the receptacles. The hopper loading device 84 is connected wirelessly or by wires to a control panel 88 which is preferably spaced apart from the actual apparatus. As shown in Fig 21 the control panel 88 is separated by a user platform 86 which is used to look into hopper 12 when the hopper lid 52 is open. The control panel 88 contains an input device, a storage device, and means for processing information received from the hopper loading device 88 and means for controlling the various components of the apparatus. Optionally the controller has a network interface for remote access and control.

The process for sterilising and shredding the waste includes the following steps:

1. The apparatus is preheated using the steam in the steam jacket 124. 2. the waste receptacle containing the waste to be treated is first scanned by the RFID scanner and weighed, this information is sent to the controller for storage.

3. The operator holds down the appropriate button that opens the hopper lid 52 and lifts the bin contents into the chamber.

4. Next a further button is pressed to lower the hopper lid 52 and lock it into place.

5. Once the system is secured the vacuum pump 76 extracts the air out of the chamber.

6. Steam is introduced under pressure and the shredder 14 is

activated to commence treatment once the temperature and pressure requirements are met, namely 135 degrees Celsius and 220 kPa.

7. Shredded waste travels into the first transfer and treatment auger 16 and thereafter into the second transfer and treatment auger 18 where it delivers the shredded waste back into the hopper 12 for reprocessing.

8. The above step is repeated until the shredding and sterilisation process is complete.

9. Once the sterilisation process is complete the steam is then

condensed via the heat exchanger and collected in a tank.

10. Once the pressure set point is reached the vacuum pump 76 starts removing the remainder of steam and then pulls a vacuum.

11. The waste is then circulated under a vacuum through the

pressure vessel in the same manner as the explained above for a set time, at the completion of this the vacuum pump 76 is run again to remove the built up pressure. This process helps dry the waste in the system.

12. Once the correct vacuum set point is reached the outlet gate 20 is opened and the auger screws 50 in the second transfer and treatment auger 18 are reversed to allow the waste to be emptied into the outlet bin.

13. While the cycle is running the sterilisation data is collected and logged to the controller 88.

14. At the completion of the cycle the data is transferred to the

storage unit of the controller 88 which may comprise a SD card for easy access.

The specifications for the present embodiment shown in the figures include:

1. Tanks: feedwater 50 Litres, blow down tank: 250L

2. Pressure - minimum pressure for operation 220kPa up to a

maximum of 350kPa

3. Weight: 5 ton

4. Size/Footprint: 5.2m long x 3.7m wide x 3m high

5. Energy consumption, average 40Kw/hr

6. Capacity: treatment chamber 80 capacity 620L, hopper capacity 318L

7. Time for average cycle is approximately 15 minutes.

INDUSTRIAL APPLICABILITY

The present invention has industrial applicability in the area of medical waste treatment, and the treatment of other wastes that require granulating and sterilising, including organic waste or food waste.

Claims

1. A pressurised waste treatment apparatus comprising:

i. a hopper having a resealable inlet for receiving waste to be treated; ii. a shredder in communication with the hopper which is comprised of at least two counter rotating shafts set at an angle on which are mounted a plurality of spaced apart shredder blades, the blades being so arranged on each shaft so as to be between the blades on the other shaft and wherein when the shafts are contra rotated with the top portions of the blades moving towards each other they draw the received waste into and through an outlet of the shredder; and iii. means for transferring the shredded waste from the outlet of the

shredder back into the hopper;

iv. steam generation and distribution means adapted to supply sufficient steam and pressure to sterilise the waste to be treated;

v. means for ejecting the shredded waste post treatment from the

apparatus.

2. The apparatus of claim 1 wherein the means for transferring the shredded waste from the outlet of the shredder back into the hopper is provided by:

i. a first transfer and treatment auger in communication with the outlet of the shredder which receives shredded waste and agitates it as it raises it simultaneously to its outlet;

ii. a second transfer and treatment auger which has an inlet in

communication with the outlet of the first transfer and treatment auger, and where the second transfer and treatment auger is bi- directional and has two outlets, either side of its inlet, wherein the first outlet is in communication with the hopper, and wherein the second outlet is fitted with a gate for discharging treated and shredded waste.

3. The apparatus of claim 2 where the hopper, shredder, the first transfer and treatment auger and the second transfer and treatment auger define a pressure vessel and wherein the steam generation and distribution means adapted to supply sufficient steam and pressure to sterilise the waste to be treated is includes a steam jacket that envelopes the pressure vessel and wherein generated steam is circulated through the steam jacket to keep the temperature of the components at a set level and to reduce condensation of the steam at remote parts of the pressure vessel as well as within the pressure vessel.

4. The waste treatment apparatus of claim 3 wherein the resealable inlet is comprised of a hopper inlet and a lid and wherein the resealable inlet incorporates a mechanism that prevents the lid fully opening under pressure but which allows the lid to partially open under pressure, thereby allowing the pressure vessel to vent its contents without the lid opening explosively.

5. The waste treatment apparatus of claim 4 wherein mechanism

comprises teeth on the lid and on the hopper inlet that interconnect to lock the lid in place on the hopper inlet in one of two positions by way of a step or recessed portion formed into one of the set of teeth, wherein the first position provides a seal between the lid and the hopper inlet, and wherein the second position provides a vent between the lid and the hopper inlet.

6. The waste treatment apparatus of claim 5 wherein the gate of the second transfer and treatment auger is a hydraulically operated ball valve that incorporates a seal and scraper that are adapted to clean the surface of the ball as it is rotated so as to prevent the valve from becoming jammed.

7. The waste treatment apparatus of claim 5 wherein shafts of the shredder and/or augers are mounted at an elevated angle and wherein the motors and/or drives that rotate the shafts are located at the elevated ends of the shafts.

8. The waste treatment apparatus of claim 7 wherein the ends of the shafts are mounted in bearing housings that have within them, bearings that are separated from the pressurised interior of the apparatus by means of at least a primary seal and at least a secondary seal wherein the secondary seal performs the function of a:

a. mechanical barrier;

b. pressure seal that is activated in the absence of pressure on the seal; and

c. vacuum seal.

9. The waste treatment apparatus of claim 5 which further comprise two self contained steam circuits wherein the first steam circuit is used to heat the pressure vessel by introducing steam via steam inlet lines, into the steam jacket of the apparatus, and wherein the steam that condenses in this first circuit is returned, via a condensation tank, to a boiler of the first steam circuit for subsequent recirculation through the steam jacket, and wherein the second steam circuit supplies steam directly into the pressure vessel via steam inlet valves for direct contact with the waste, and wherein the steam in the apparatus is discharged through a heat exchange of the second circuit which condenses the steam and collects the resultant waste water, thereby preventing any emissions of the steam used to treat the shredded waste, directly into the atmosphere.

10. The waste treatment apparatus of claim 9 wherein the steam jacket covers more than 30% to 50% of the apparatus.

11. The waste treatment apparatus of claim 2 wherein the auger outlets are located such that waste exiting the augers falls out of the outlet before it can accumulate near the auger bearing housings connected to motors that drive the augers.

12. The waste treatment apparatus of claim 2 wherein the hopper, shredder, first treatment and transfer auger and second treatment and transfer auger are arranged in a triangular formation.

13. The waste treatment apparatus of claim 2 wherein the hopper, shredder, first treatment and transfer auger, and second treatment and transfer auger are mounted in a frame comprised of at least two pivotally connected sub frames mounted on wheels wherein the frame is able to be pivoted open to allow access by a person to the components of the apparatus.

14. The waste treatment apparatus of claim 13 wherein the apparatus further comprises a receptacle tipping mechanism for lifting, tipping and emptying receptacles containing waste into the resealable inlet of the hopper.

15. The waste treatment apparatus of claim 14 wherein the apparatus further comprises an RFID sensor that is adapted to read RFID tags present on the receptacles and wherein the information read from the RFID tag is sent to a PLC unit.

16. The waste treatment apparatus of claim 5 which further comprises a set of electronic scales for weighing the receptacle, and, wherein the weight of the receptacle is sent to the PLC, along with any available RFID data.

17. The waste treatment apparatus of claim 16 wherein the controls for the apparatus are operated remotely from the apparatus, where control signals are sent to the device either wirelessly or by using a wired connection.

18. The waste treatment apparatus of claim 2 where the hopper is adapted to receive one 240L receptacle, or two 120L receptacles where they are cycled through the apparatus such that the shredded waste resulting from treatment is ready for disposal in approximately 15 mins using no more than 40Kw/hr of electricity.

19. The waste treatment apparatus of claim 18 wherein the pressure contained therein is at least 230Kpa.

20. A method of treating waste using the apparatus any of claims 1 to 19 incorporating the following steps:

a. filling the steam jacket with steam to heat the apparatus;

b. loading the combined hopper/shredder with waste to be treated via the inlet;

c. extracting the air from the apparatus using a vacuum pump of the apparatus;

e. activating the shredder ;

f. pulling the waste through the shredder into the first treatment and transfer auger and thereafter into the second treatment and transfer auger which is set to deliver the contents of the auger back to the combined hopper/shredder;

g. repeating the above step until the sterilisation process is complete;

i. cycling the shredded and sterilised waste in a vacuum through the shredder, first treatment and transfer auger and thereafter into the second treatment and transfer auger so as to dry the shredded and sterilised waste; and

j. opening the outlet gate and reversing the direction of the second