AU2017203130B2

AU2017203130B2 - Apparatus for treating medical waste

Info

Publication number: AU2017203130B2
Application number: AU2017203130A
Authority: AU
Inventors: Yaron Keret; Aharon Nir
Original assignee: Alytech Pty Ltd
Current assignee: Alytech Pty Ltd
Priority date: 2016-05-11
Filing date: 2017-05-11
Publication date: 2020-10-29
Anticipated expiration: 2037-05-11
Also published as: AU2017203130A1

Abstract

A medical waste treatment apparatus grinds medical waste such as bandages, syringes, facemasks, gloves etc. into small particles and drops the ground material into a lower treatment tank which is filled with water and a disinfectant/sterilizing agent. The contents of the treatment tank is agitated by a number of agitator rotors. After a holding period (typically up to 20 mins) in the tank, the liquid is drained from the tank and into a sewer outlet. The sterilized ground waste settles into a lower sump area in the treatment tank and is augured out by an upwardly inclined auger conveyor where the auger extends into the sump area. The sterilized ground medical waste can be bagged or otherwise collected and disposed of in conventional refuse bins.

Description

AUSTRALIA PATENTSACT1990

COMPLETE SPECIFICATION APPARATUS FOR TREATING MEDICAL WASTE

The following statement is a description of the invention:

APPARATUS FOR TREATING MEDICAL WSTE TECHNICAL FIELD

The present invention is directed to an apparatus for grinding and treating medical waste material to enable the waste material to be disposed in a safe manner.

BACKGROUND

Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

Medical waste material comprises bandages, needles, syringes, gloves, masks, infusion bags, aprons, valves, human waste and the like. This waste material is not reused, is potentially hazardous and needs to be rendered harmless for disposal. Large incinerators are used to dispose of medical waste but these are generally unsuited for smaller facilities.

It is known to provide an apparatus that treats medical waste by shredding the waste material and then contacting the shredded material with a decontaminating disinfectant liquid such as Alymed Steriiser TM which is an aqueous formulation containing hydrogen peroxide, acetic acid and sulfuric acid that may be obtained from the present applicants. Other disinfectant liquids are also known including peroxides. Such an apparatus is described in W02013/106551. The shredding action does not always reduce the size of the waste material to the desired size ( for instance, bandages may be shredded into long strips), and thus the known apparatus requires the shredded material and the disinfectant solution to be pumped back to the shredder one or more times until the desired size is reached. This requires the apparatus to have a slurry pump and associated pipework to recycle the mixture of shred waste and liquid disinfectant back through the shredder. The apparatus is therefore larger and more expensive. Other disadvantages are that the mixture needs to have a high liquid content to enable the shredded waste and liquid to be pumped which requires larger tanks, more disinfectant and results in the production of more liquid waste to the sewer. It is also known for the mixture to clog the recycle loop. The shredder is subjected to the liquid mixture that can reduce the efficiency of the shredder due to the high water content in the mixture passing through the shredder.

It is an object of the present invention to provide a relatively compact apparatus for the treatment of hazardous waste such as medical waste and which can be used in hospitals, veterinary clinics, dental practices, medical centers and the like and which is a useful alternative to those apparatus that are presently commercially available.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an apparatus for treating medical waste, the apparatus comprising an inlet, a grinding assembly associated with the inlet to grind the waste, a treatment tank associated with the grinding assembly such that ground waste material passes into the treatment tank, and a conveyor to convey treated waste material from the treatment tank to an outlet.

In this manner, the medical waste is ground in a "dry" state by the grinding assembly before passing into the treatment tank. Thus, the grinding assembly is not presented with wet "slurry" which is the case with a known apparatus that recycles a slurry of shredded material and disinfectant back into the shredder. The grinding assembly can grind the waste material into a desired size range in a single pass and therefore a recycle loop is not required. The ground waste material can then pass into a treatment tank where it can be TM treated with a disinfectant an example of which can be Alymed Steriliser ,

though others may also be used. After being disinfected, the disinfected ground waste material can be conveyed directly from the treatment tank to an outlet for bagging or other type of safe disposal as general waste.

The apparatus uses less water and less disinfectant as there is no requirement to dilute the waste material to enable it to be pumped back into a shredder for multiple shredding passes. This can make the apparatus more compact, less expensive, easier to use, and therefore more suited also to smaller clinics. The conveyor conveys the treated ground waste material directly from the treatment tank to the outlet so there is no requirement for a separate separation tank or other bulky equipment.

The apparatus is particularly suited for treating medical waste and particularly single use medical waste that requires safe disposal and is usually not reused. However, it is also envisaged that the apparatus can be used for other types of hazardous material that can benefit from the grinding and disinfecting sequence provided by the present apparatus.

The apparatus has an inlet. The inlet may comprise a hopper. The hopper may have an upper lid that can be opened and closed, and a lower open area to enable waste material to be conveyed to the grinding assembly. The lid is preferably opened and closed by an electro/mechanical actuator. The hopper may be associated with a push means or feed means to facilitate passage of the waste material in the hopper towards the grinding assembly. The push means may comprise a push/feed plate which may be hinged to push against the waste material in the hopper. The push plate may also be spring biased or otherwise biased to urge the waste material towards the grinding assembly. The positioning of the feed/push plate is preferably by an electro/mechanical actuator. The lid and push plate are suitably controlled by a controller.

In another embodiment of the invention a press plate may be located within the hopper and arranged to press waste material toward the grinding assembly. Preferably the press plate is operated by a hydraulic actuator controlled by a controller such as a programmable logic controller (PLC).

At least one spray nozzle is suitably associated with the hopper to assist with periodic washing out of the hopper and grinding assembly. The at least one nozzle is suitably controlled by a controller, such as a programmable logic controller (PLC) or other electronic control device.

The grinding assembly is suitably arranged below the hopper to grind the waste material. The grinding assembly suitably comprises a rotating grinding roller and a fixed grinding plate between which the waste material passes and is ground into a desirable size range. The spacing between the grinding roller and the grinding plate may be adjustable inter alia to adjust the size range of the waste material and also the type of material to be ground.

The grinding roller may be substantially cylindrical having a side wall and opposed end walls. One end wall may include a protruding axial pin that can be journalled or otherwise supported into a side wall or other supporting part. The other end wall may include a projecting shaft that can engage with a drive means to drive the grinding roller in a rotating manner. The drive means may comprise a drive belt connected to a drive motor. Alternatively, the projecting shaft may engage with a drive shaft via a gear. The grinding roller typically rotates at between 70-120RPM.

The side wall of the grinding roller typically includes a multiplicity of cutting teeth. The cutting teeth may extend from one end wall to the other end wall. Suitably, the cutting teeth are substantially equally spaced about the side wall. Suitably, the cutting teeth project from the side wall of the grinding roller. The teeth may comprise cutting blades. Suitably, the cutting teeth extend along the side wall in longitudinal rows. Each row may comprise between 6-20 teeth depending on the length of the roller. The roller may comprise between 6-12 longitudinal rows depending on the diameter of the grinding roller. The longitudinal rows are preferably equally spaced apart. The teeth in each longitudinal row are preferably arranged to be offset between rows, inter alia, to ensure an efficient grinding action. The teeth may be removably mounted to the roller. The roller may be solid or hollow or may be partially solid with weight reducing voids. The roller may be formed from smaller separate sub rollers joined together or rotating together to form the grinding roller. The length of the grinding roller may vary but it is envisaged that for most apparatus a suitable length will be between 40-150 cm. The diameter of the grinding roller may vary but it is envisaged that for most apparatus a suitable diameter will be between 10-30 cm.

The fixed grinding plate may comprise a substantially rigid metal plate like member that can be attached by any suitable means including fasteners to a support. The plate typically includes a leading edge containing a multiplicity of recesses conforming to the projecting teeth on the grinding roller. The recesses may be sharpened to assist in the grinding action. The fixed grinding plate can be adjusted to adjust the spacing between the grinding plate and the grinding roller. The grinding roller is suitably controlled by a controller.

A perforated plate may be located beneath the grinding roller to prevent matter of a size that is larger than perforations through the plate from the passing therethrough.

The apparatus includes a treatment tank. The treatment tank may be positioned below the grinding assembly such that ground material falls into the treatment tank. Alternatively, a conduit, or a guide plate, or a channel or similar may be provided to direct the ground material into the treatment tank.

The treatment tank may have a volume suitable to treat all the material in the hopper that passes through the grinder and passes into the treatment tank. Thus, the volume of the treatment tank will depend upon the size of the hopper. It is envisaged that the treatment tank will have a treatment volume of between 20-150 L. This can of course vary to suit.

The treatment tank suitably includes a lower collection area in which the ground material can settle. The lower collection area may comprise a sump area. Suitably, the lower wall of the treatment tank is inclined to facilitate settling of the treated ground material into the sump area. Preferably two controllable and rotatable agitators are located in the treatment tank.

A drain valve or disposal valve is suitably provided in the treatment tank to drain liquid from the tank. The valve is preferably a full flow electrically actuated valve which allows the sterilisation liquid to be gravity fed down a floor vented drain pipe. The valve is suitably controlled by a controller.

The apparatus includes a conveyor. The conveyor suitably comprises an auger conveyor. The auger conveyor suitably comprises a spiral auger within a tubular housing. The spiral auger may comprise a helical flight or a helical spring type auger or any other suitable type of auger. The conveyor has an upper outlet and a lower inlet. The conveyor is preferably elevated or upwardly inclined such that conveying of the treated ground material occurs along an upwardly inclined or an upward direction, inter alia, to facilitate draining of liquid from the ground material as the ground material is conveyed.

The lower inlet of the conveyor is typically in direct communication with the treatment tank. Suitably, the lower end of the conveyor housing (the tubular housing) terminates in an upper part of the treatment tank while the auger extends further into the treatment tank and suitably terminates in a lower or preferably a lowermost portion of the treatment tank which may comprise the sump area. The conveyor is suitably controlled by the controller.

In another aspect of the invention there is provided a method for treating medical waste comprising grinding the waste material, contacting the waste material with an aqueous mixture containing disinfectant in a treatment tank and for a time sufficient to disinfect the ground waste material, draining off the liquid in the treatment tank, allowing the treated ground waste material to settle in a lower part of the treatment tank and conveying the treated ground waste material through an auger conveyor and along an upward inclination to an outlet.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows: Figure 1. Illustrates a view of an apparatus having an upper hopper with a lid in the closed position. Figure 2. Illustrates the apparatus of figure 1 with the lid in the open position. Figure 3. Illustrates in greater detail the treatment tank of the apparatus. Figure 4. Illustrates the grinding roller. Figure 5. Illustrates a section view of the apparatus. Figure 6. Illustrates the grinding assembly comprising the grinding roller and a fixed grinding plate. Figure 7. Illustrates the grinding assembly from a different view. Figure 8. Is a block diagram of the apparatus. Figure 9. Is a block diagram showing the various sensors and actuators of the apparatus that are controlled by a central controller of the apparatus. Figure 10 is a view of the front, top and left hand side of a medical waste treatment apparatus according to a second and preferred embodiment of the present invention. Figure 11 is a view of the front, top and right hand side of various internal components of the apparatus of Figure 10. Figure 12 is a view of the rear, top and left hand side of components the apparatus. Figure 13 is a view of the front, top and right hand side of components of the hopper, grinding assembly, treatment tank and conveyor of the apparatus of Figure 10. Figure 14 is a cross sectional view corresponding to Figure 13 along section B-B' as indicated in Figure 13.

Figure 15 is a cross sectional view corresponding to Figure 12 along section A-A' as indicated in Figure 12. Figure 16 is a view of the front, top and right hand side of a grinding assembly of the apparatus of Figure 10. Figure 17 is a view of the underside, front and right hand side of the grinding assembly. Figure 18 is a detail view of the rear of the apparatus of Figure 10. Figure 19 is a view through an inspection window of the treatment tank of the apparatus of Figure 10 revealing agitators within the tank. Figure 20 is a detail view of the front of the apparatus of Figure 10. Figure 21 is a block diagram of the control circuit of the apparatus of Figure 10. Figure 22 is a schematic diagram of the apparatus of Figure 10 indicating how the control circuit interfaces with various components of the apparatus. Figure 23 is an exemplary timing chart illustrating a preferred sequence of processes that the apparatus of Figure 10 goes through under control of the PLC.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring to figures 1 and 2 there is illustrated an apparatus 10 for treating medical waste, the apparatus comprising an inlet 12, a grinding assembly 13 associated with the inlet to grind the waste, a treatment tank 14 associated with the grinding assembly such that ground waste material passes into the treatment tank and a conveyor 15 to convey treated waste material from the treatment tank to an outlet 16 (outlet 16 best illustrated in figure 3).

The apparatus 10 includes an upper hopper 18 which is fitted with a lid 19 that can move between a closed position illustrated in figure 1 and an open position illustrated in figure 2. The hopper opening size, in the presently described embodiment, is 700mm x 500mm. Waste material is hand fed into the hopper. In a further embodiment of the invention the hopper may be fitted with a lift and tilt assembly for lifting a bin of medical waste and emptying its contents into the hopper.

The hopper 18 is provided with a curved face 34 best illustrated in figure 2 and figure 5 to guide the waste material towards the grinding assembly 13. The grinding assembly 13 is located in a lower open part of the hopper such that the lower part of the hopper exposes the grinding assembly 13.

To further assist in movement of the waste material in the hopper into the grinding assembly 13, there is provided a push/feed plate 21 which is best illustrated in figure 5. Push/feed plate 21 comprises an elongate metal plate that is hinged at hinge 22. The push/feed plate 21 can hinge between an upper position where the push/feed plate sits underneath lid 19 (the upper position not illustrated), and a lowered position illustrated in figure 5 with the push plate terminates above the grinding assembly. The push/feed plate 21 has sufficient mass to provide a pushing action on the waste material in the hopper to ensure that all the waste material eventually passes through the grinding assembly. To assist, the push/feed plate includes an actuator (not illustrated).

The grinding assembly 13 comprises a grinding roller 24 (best illustrated in figure 4 and figures 6-7) and a fixed grinding plate 25 illustrated in figure 2, figure 5, and figure 6-7. In the presently described embodiment the grinding roller 24 has a length of about 700mm, a diameter of about 250mm, rotates at about 85-100rpm about its longitudinal axis and has opposed end faces, from one of which extends a short stub axle 26 (see figure 4) to enable the roller to be journalled into a side wall 37. From the other end face there extends a longer axle 27 that contains radial splines 35 which mate with an internally splined socket (not illustrated) attached to the drive shaft of an electric motor 36 (see figure 2) which drives the grinding roller 24. Of course, other types of driving arrangements can be used including the use of a drive belt or a drive gear.

The grinding roller 24 contains a multiplicity of sharp knife-like teeth 28 which project above the periphery of the roller. The teeth are spaced equally apart in separate longitudinal rows extending from one end face to the other end face of the roll. In the embodiment illustrated in figure 4 each longitudinal row (e.g. row "X" in figure 4) is provided with nine equally spaced apart teeth. The number of teeth per row, and indeed the number of rows of teeth, can of course vary depending on the length and diameter of the grinding roller 24. The roller 24 will typically have between 6-10 longitudinal rows equally spaced apart on the roller. The teeth in one row are offset relative to the teeth in an adjacent row. For instance, referring to figure 4, it can be seen that teeth 28a and 28b in one row are offset relative to teeth 28c and 28d in an adjacent row. This ensures a good grinding action of the waste material as it passes between the grinding roller 24 and the fixed grinding plate 25.

The fixed grinding plate 25 ( figures 6 and 7) has a leading edge 29 which contains a plurality of somewhat V shaped notches or teeth which are aligned with the projecting teeth 28 on the grinding roller such that the projecting teeth 28 on the grinding roller pass into a respective V shaped notch on the grinding plate. Again, this ensures a good grinding action of the waste material.

The grinding assembly 13 locates directly underneath the open bottom of hopper 18 and this part of the apparatus contains opposed side wall plates 38, 39 (best illustrated in figures 5 and 7). Each side wall plate 38, 39 supports an angled bracket 40, 41 and the fixed grinding plate 25 (and 25a) is screwed or otherwise attached to the angled bracket. This arrangement may enable the grinding roller to be rotated either clockwise or anticlockwise while still contacting a grinding plate. To assist, the teeth 28 on the grinding roller may be symmetrical which means that they can cut and grind through the waste material irrespective of whether the roller is rotating clockwise or anticlockwise.

Below the grinding assembly 13 is a treatment tank 14. The treatment tank is situated below the grinding assembly such that ground material will drop into the treatment tank. The size of the treatment tank is preferably such that a full hopper of waste material can be ground and the ground waste material can be dropped in the treatment tank with the tank being large enough to treat all the ground material.

The treatment tank has an inclined ower wall 31 best illustrated at least in figure 1 and figure 3 with the lowermost part comprising a sump area 30 best illustrated at least in figure 3. Thus, ground material will settle in the sump area.

A conveyor 15 conveys the treated waste material from the treatment tank to outlet 16. Outlet 16 is best illustrated in figure 3. The conveyor 15 comprises an auger rotating in an elongate tubular member 43, the auger being rotated by electric motor 42. The conveyor is upwardly inclined, inter alia, to make collecting treated material passing through outlet 16 convenient and also to assist in draining treatment liquid from the treated material as it passes upwardly through the auger conveyor 15.

The lower end of the outer tubular member 43 of the auger conveyor 15 terminates in a conveyor inlet 32 (see figure 5) in an upper part of the treatment tank 14. However, the auger itself (not illustrated) can pass further into the lowermost sump area 30.

In use, waste material is hand fed into the hopper and the hopper lid is automatically raised and lowered (see below). The waste material is then ground by the grinding assembly and drops into the lower treatment/holding tank 14. At this stage, water can be piped into the treatment tank and mains water can be used via the usual pipework and a solenoid valve to operate and to regulate the water inlet. The solenoid valve is operated by a Control Panel 45 (see figure 8) and is described below. It is envisaged that approximately 100 L of water will pass into the treatment tank 14. As well, a measured amount of disinfectant is pumped from a holding vessel 46 (see figure 8) into the holding tank 14 via an arrangement of pipes and valves..

If desired, an agitator such as a driven rotor may be provided to ensure thorough mixing and contact of the ground waste material with the aqueous disinfectant solution in the holding tank. After the correct amount of contact time (this can be about 20 min) the liquid is drained from the treatment tank via a lower disposal outlet/valve 33 (see figure 1) and this liquid can be drained into the sewer system. The treated ground material can then be removed from the holding tank by the auger conveyor 15 to pass through outlet 16 (see figure 3) and usually into a collection bag, sack, container and the like. About 10kg of waste can be treated in about 100 liters per cycle. With the average cycle being 20 mins, three cycles per hour can be achieved.

It is envisaged that the waste material will first be ground and dropped into the treatment tank before water and disinfectant is passed into the tank. However, it is also possible for the treatment tank to already contain liquid before the waste material is ground and dropped into the tank. It is also envisaged that liquid will be passed into the tank as the waste material is being ground by the auger.

Further details of the apparatus will now be described with reference to Figures 8 and 9.

Loading Hopper lid manual operation The lid 19 is opened and closed by an electro/mechanical actuator 101. The actuator is an electro/mechanical 24V DC actuator. Integral to the actuator 101 are end of travel switches 109 for self-protection of the actuator 101. The PLC 100 is programmed for an operator to use left and right push buttons 103, 105 in unison on a control panel 45 to bring actuator 101 to close the lid and a single push button to open the lid. A time based, close and open, control is programmed into the PLC 100. The end of travel positions of the lid and/or actuator 101 will be "spring softened" and the internal end of travel switches 109 sensed by the PLC 100 to stop the grinder motor 36 when the lid is open.

Hopper Push/Feed Plate 21 The PLC 100 is programmed so that excess load on the grinder, as detected by the variable speed drive (VSD) 110 for the grinder motor 36, will cause the lid actuator 101, and thus the feed plate to "pause" during the loading stages.

Hopper Feed Plate Spray system The load side face of the feed plate has an integral spray array of nozzles 48 to assist with washing out etc. The two liquids are piped from their sources to the Holding Tank and Paddle. Two three way valves 113 are fitted to direct the flow either to the Holding Tank or Paddle. This valve set 113 is controlled via the PLC 100 which senses Holding Tank (by default) route/Paddle route position feedback from the valve set 113.

Grinding Assembly 13 The Grinding Assembly 13 is permanently mounted at the bottom and all the load (waste material) is gradually presented to the shredding blades/teeth 28 to pass into the treatment/holding tank 14. The motor 36 of the Grinding Assembly 13 is controlled by the VSD 110 to manage on/off, direction, speed, load and faults etc. The motor 36 is a 3phase 415V AC 7.5 kW rated 4Pole TEFC industry standard motor directly connected to the shredder shaft via reduction gearbox giving a shredder shaft speed of approx. 100RPM. The motor 36 has an industry standard VSD 110 managed by the PLC 100. The VSD 110 is controlled by direct wiring for the minimal Start/Stop, Fwd/Rev, Overload, and fault activity etc via user interface 115 which is coupled to the VSD via a bus using the MODBUS communication protocol.

Holding/Treatment Tank 14 Drain valve The tank 14 has a drain valve 119 which is a full flow electrically actuated valve that allows the sterilisation liquid to be gravity feed down a floor vented, pipe. Fully open and fully close feed back to the PLC is required on this valve.

Discharge Auger motor 42 This motor 42 is a 3phase 415V AC 0.18kW 4Pole TEFC industry standard motor connected to the auger shaft 121 via reduction gearbox 123. Auger screw speed is approximately 100RPM. The motor 42 is controlled by a VSD 125. The VSD is controlled by an interface 127 that is coupled to the VSD by a bus using communications according to the MODBUS protocol. The interface 127 allows a user to implement Start/Stop, Fwd/Rev, Overload, and fault activity actions etc for the VSD 125.

Sterilizer Dosing System The user site has a Disinfectant Holding Vessel 46 (see figure 8) adjacent to the machine. A dosing pump 129 (24V DC) is fitted on the machine and is controlled via the PLC 100. A Low level sensor and alarm unit 131 is fitted on the vessel. Should the vessel run low and the process run short an alarm will be set. The disinfectant solution is drawn from the storage vessel and measured into the holding tank. The flow rate is set mechanically on the dosing pump 129. The disinfectant solution may be STERCID solution TM

which is a commercially available disinfecting solution for medical waste. Other suitable solutions may also be used. In order that the distributer can know the, quantities of disinfectant that the cycles run, a calibrated pulse rate flow sensor 123 is provided that is logged by the PLC 100.

Water Addition System Water at mains pressure (40PSI nominally 2.6BAR) is piped into the holding/treatment tank 14 via an inlet valve 135. The inlet valve is electrically operated 24V DC This valve is has fully open fully closed feed back to the PLC 100 so that the PLC can sense the valve's state..

Electrical distribution A separate enclosure is provided for circuit breakers and the VSDs.

Control System A separate enclosure is provided for the PLC and all low voltage control components. The principle control devices are the PLC and the interface 45. The interface 45 includes a display 149 upon which screens of a Human Machine Interface (HMI) implemented by the programmed PLC 100 are presented.

Safety considerations An Error / Service (E/S) push Button 106 is mounted on the front panel 45. The PLC 100 is programmed so that operation of the E/S button 106 will depower the common 3phase power contactor 126 that supplies the VSD's

110, 125 (Grinder and Auger) and other minor motors and valves etc. The process timers running at the time that are implemented by PLC 100 are "held" to ensure short run times do not eventuate and the waste is not properly processed.. The "restoration" process after the operation of the E/S button 106 is as follows. Upon releasing the E/S the cycle will continue but not dump the water or run the discharge auger. A technician will call and decide the next steps and will have Manual mode access codes to access service routines of the PLC.

Process Cycle A cycle is a process that can go through all the steps with no operator observation or intervention. The PLC is programmed to implement a Cycle Selection (Recipe) resource to allow for a variety of process/machine requirements.

Process Cycle control Given the existence of the recipe resource to run the processes no declaration of the process can be scheduled here. The actions and devices that are scheduled in the recipe are as follows: Device/Process Action Hopper Lid Open close Plate Fwd/Rev Liquids Injection Treatment Tank/Hopper Amount Disinfectant Amount Hold Tank Fill On/Off Shredder On/Fwd/Reverse/Speed/ Off Holding Tank Discharge Open Close Discharge Auger On/Fwd/Rev Off Wash Time/Amount Delay Time End Activate By selecting a device/process and combining an action a set of steps will constitute a cycle that can be started via the push buttons on the front panel and the machine left to execute those steps to the end.

Process Cycle management PLC 100 is programmed to implement an HMI comprising user interaction screen that are displayed by means of display 149. The HMI includes screens that allow the origination, storage, editing and selection of the user's collection of recipes. In the presently described embodiment of the invention 10 recipes of up to 50 stages are provided for via the PLC/HMI.

Remote Support Each machine has a remote access assembly 150. The remote access assembly comprises a Mobile/Cellular or local Ethernet communication assembly that is able to communicate with the client's IT infrastructure. It may need to be stored "internally" then relocated "externally" when access is needed. The distributor requires access to the HMI quarterly to log the following: - Successful cycles, unsuccessful cycles and disinfectant quantities consumed. The reason for an unsuccessful cycle would first be indicated by the current alarm/alarms etc. The alarm counts would be the next information source to work thru whereby the highest count would be a clue to reasons etc.

Operating modes The machine can be set to Auto or Manual. In Auto the operator will have a start cycle button to push after checking on the HMI via display 149 that the appropriate recipe has been chosen. The manual mode is setup to provide assistance in trouble shooting failure issues and can be only accessed by a qualified technician. Each motor, valve, sensor etc. can be switched on and off or the value of a sensor/switch etc. read.

Warning/Alarms When the machine and devices design is completed a list of alarms will be drawn up for approval. A Cycle Complete light (Blue) 153 is fitted on the Operator Panel 45. An advantage of the apparatus is much lower cost to the owner of the waste by eliminating costly and dangerous transportation of medical waste. The volume of the process waste can be reduced by 80% and there is no need for paper trail. The unit is fully automatic with small footprint. It also use 50% less water in every cycle allowing redaction of 50% of amount of sterilizer of every cycle and keeping the required sterilizer construction. The apparatus can be larger to be able to process 240 litter waste bins, with bin lifter and bin washer.

The apparatus of the embodiment has the following characteristics Total Height 1500mm Total Width 2000mm Ground to Hopper Lip 1000mm Shredder chamber Opening 700mm x 500mm Hopper Opening 700mm x 500mm Grinder Shaft Length 700mm Number of Cutters 54 Grinder Diameter 250mm Grinder Shaft Rotation Speed 72 RPM (variable) Grinder Chamber Opening 700 x 500 Hopper Height 1500mm Loading Height 1000mm Total Height 1500mm Footprint 2000mm x 1000mm Weight 450 kg Capacity/Throughput Rate in 36KG Per Hour Kilograms/Hour Capacity/Throughput Rate in 300 Litres Per Hour litters/Hour Water Consumption 25 litres Per Cycle Sterilizer Consumption Per Cycle 150mls-300ml Per Cycle (Dependent on Waste) Sterilizer Type Used Alymed Steriliser

A second embodiment of a medical waste treatment apparatus 210 according to an embodiment of the present invention will now be described with reference to Figures 10 onwards.

The apparatus 210 comprises a frame 208 which supports various components and to which a number of panels 206 are fastened as shown in Figure 10. Figure 11 shows the apparatus 210 with the covers 206 removed revealing the internal arrangement of the apparatus.

The apparatus 210 includes an upper hopper 218 presenting an inlet 212 into which waste material is fed during use. The hopper 218 includes a downwardly and inwardly slanting face 234, best seen in the cross sectional views of figures 14 and 15 to guide the waste assembly towards a grinding assembly 213 which is located beneath the hopper 218. A hydraulically operated press plate 212 is provided for urging waste material deposited into the hopper 218 downward to the grinding assembly 213. The press swings about a pivot 222 in order that it may be swung down to press the waste material against the grinding assembly 213 and to ensure that all the waste proceeds through the grinding assembly.

The grinding assembly 213 is best seen in Figures 16 (top view) and 17 (underside view). The grinding assembly 213 comprises a rectangular chassis 204 having an open top and an open underside, into which there is mounted a grinding roller 224 and a fixed grinding plate 225. The roller 225 is mounted to rotate within the chassis 204 and has an axle 226 that extends from the axle and to which there is fixed a pulley 204 (illustrated in Figure 11). The pulley 204 is driven by a motor 236 that is disposed parallel to roller 224, via belts 202. The grinding roller 224 has a length of about 700mm, a diameter of about 250mm, rotates at about 70-100rpm about its longitudinal axis

Returning again to Figure 16, the grinding roller 24 contains a multipliclity of sharp, knife-like teeth 228 which project above the periphery of the roller 224. The teeth 228 are equi-spaced in separate longitudinal rows extending from one end to the other of the roller 224. The arrangement of the teeth 228 corresponds to that of teeth 28 of the grinding roller 28 of the first embodiment which is illustrated in Figure 4, for example. The fixed grinding plate 225 has a leading edge 229 which is formed with a plurality of V-shaped notches or teeth which are aligned with the projecting teeth 228 on the grinding roller so that during rotation of the roller the projecting teeth 228 on the grinding roller 224 pass into a respective V-shaped notch on the grinding plate 225. As best seen in Figure 17, the grinding assembly 213 further includes a perforated plate 200 that is fastened across the underside of the frame 204 and which prevents matter that is oversized relative to the perforations through the plate 200 from proceeding through the grinding assembly.

As best seen in Figures 12 and 13, below the grinding assembly 213 there is located a treatment tank 214 which receives ground material that falls from the grinding assembly 213 in use. The treatment tank has an inclined lower wall 231 with the lowermost part comprising a sump area 230, as may be seen in Figure 15, for example. Thus ground material falling from the grinding assembly 213 will tend to settle in the sump area 230. A conveyor 215 is provided that extends from the sump area 230 upwardly and outwardly to an outlet 216. The conveyor 215 is of the same type as conveyor 15 of the first embodiment of the invention and includes a tube with a "D" shaped cross section that houses an internal elongate auger (item 168 of Figure 22) that is driven by a motor (item 242 of Figure 22) in order to convey matter from the tank 214 up to the outlet 216.

In the presently described second embodiment an agitator comprising two driven rotors 221a, 221b is provided. Figure 18 is a detailed view of the rearside of the apparatus 210 wherein ends of the rotors 221a and 221b that protrude through the tank 214 are visible. The agitator rotors 221a and 221b terminate on agitator pulleys 189a, 189b that are coupled via a belt 188 which is tensioned by tensioning wheel 187. Figure 20 is a detail view of the front of the apparatus wherein the tank 214 is visible. A second end of the agitator rotor 221a extends from the tank 214 and is driven by a gearbox and electric motor assembly 186. A hydraulic pump 185 that is powered by an electric motor 184 is also provided for supplying hydraulic pressure to various hydraulic actuators such as a hydraulic actuator 180 (Figure 22) for operating the press plate 212. Accordingly, driving the first agitator rotor 221a in turn also drives the second rotor 221b by means of the rotor belt 188. The status of the rotors and the contents of the tank may be ascertained by viewing through inspection window 183, which is mounted on the side of the tank 214. The rotors are comprised of elongate metal shafts from which radially extend bendable and resilient plastic agitation fingers 182. In use the rotors 221a and 221b rotate within the tank 214 which is filled with a sterilizing solution as previously discussed in relation to the first embodiment of the invention. The fingers 182 move through the solution in the tank and the ground material from the grinding assembly so that the ground material is thoroughly immersed and washed with the sterilising solution. The solution may be drained to sewerage when required via drain 198 (Figure 18) which is opened and closed by means of drain valve 219. It is envisaged that approximately 40L of water will pass into the treatment tank 214. As well, a measured amount of disinfectant is pumped from a holding vessel 172 (see figure 22) into the holding tank 214 via an arrangement of pipes and valves. The treated, agitated and ground material can then be removed from the holding tank by the auger conveyor 215 to pass through outlet 216 and usually into a collection bag, sack container or the like. About 15 kg of waste can be treated in about 150 liters per cycle with the average cycle being 20 mins, three cycles per hour can be achieved.

In use, liquid may be passed into the tank, for example by means of inlets 170a, 170b illustrated in figure 22, as the waste material is being ground by the grinding assembly 213.

Figure 18 also shows a number of quick release latches 197 which are provided to make it easy to quickly remove the treatment tank 214 for maintenance and cleaning purposes when necessary.

The apparatus 210 includes a programmable logic controller (or other electronic control device) which is programmed to respond to various sensors of the apparatus and to operate motors and actuators of the apparatus accordingly. Figure 21 is a block diagram of the electronic control system. It includes the PLC 201 which executes a program 170 that is stored in onboard memory. The PLC 201 is connected to a user control panel 245 which includes control buttons and a screen in similar fashion to control panel 45 of Figure 9 in relation to the first embodiment of the invention described herein. The PLC 201 is also coupled to a lid open/close control 256, emergency stop button 258, and restart button 260. The PLC 201 is connected to a shredder forward actuator 262 which causes the motor 236 to operate to rotate the grinding roller 224 of the grinding assembly 213. The PLC 201 is able to control an "Agitator on" output 264 which in turn is coupled to a solenoid for operating gearbox and motor assembly 186 to cause the agitators 221a and 221b to rotate within the tank 214. The PLC is also coupled to a "water/chemical injection treatment tank" output which causes flow controllers such as pumps and/or solenoids to operate to inject water and sterilising solution into the tank 214 when required. The PLC 201 is connected to a "Water/Chem wash hopper" output 270 that in turn operates a solenoid for operating nozzles that wash the hopper 218. The PLC is able to operate a "Drain valve open" output 272 to cause drain valve 219 to open in order to drain the tank 214 through drain pipe 198. The PLC is further able to operate an "Auger forward" output 274 to cause the motor that rotates the auger within conveyor 215 to operate in order to remove material from the tank 214. Finally the PLC is able to operate a "Drain valve close" output 276 which is in turn connected to the drain valve 219 for closing the drain valve 219.

Figure 22 is a schematic diagram of apparatus 210 showing where each of the control lines "a" to "g" from boxes 262 to 276 of the block control diagram of Figure 21 terminate. In this diagram control line "a" from "shredder forward" output 262 ultimately controls the grinder motor 236.

Control line "b" from the "Agitator on" output 264 controls the agitator and gearbox assembly 186.

Control line "c" from the "Press forward/reverse" output 266 controls the actuator 180 that operates press 212. The press plate is driven by actuator 180 which is typically provided in the form of a hydraulic ram. The Hopper Press Push/Feed Plate was designed to ensure continues feed into the grinder and element waste "bouncing" on top of the rotor. Accordingly, the press plate 212 working time is controlled by the PLC 201 (Figure 21).

Control line "d" from the "Water/chemical injection treatment tank" output 268 controls flow controllers 178a, 178b for selectively introducing water and/or sterilising chemicals from supply sources 174 and 172 via inlet sprayers 170a, 170b into tank 214. Although the diagram of Figure 22 shows two inlet sprayers 170a, 170b it is believed that 5 sprayers controlled by solenoid may be preferable to rapidly introduce fluid into, and clean the sides of, the tank.

Control line "e" from the "Water/chem wash hopper" output 270 controls flow controllers 176a, 176b for selectively introducing water and/or sterilising chemicals from supply sources 174 and 172 via wash nozzles 170a, 170b into hopper 218. Although only two controllers 176a and 176b are shown in the diagram of Figure 22 it is believed that in another embodiment of the invention it may be preferable to include seven controllable solenoid valves for directing the flow of liquid into the hopper in order to thoroughly wash all surfaces of the hopper.

Control line "f"from the "Drain valve open" output 272 controls drain valve 219 for opening that valve to facilitate draining of the treatment tank 214 through the outlet drain pipe 198.

Control line "g" from the "Auger" output 274 connects to auger motor 242 which is in turn coupled to the auger 168 to thereby operate the auger under command of the PLC 201 in order to transport waste material up out of the sump area of the treatment tank 214.

Control line "e" from the "Drain valve close" output 276 controls drain valve 219 for closing that valve to prevent draining of the treatment tank 214 through the outlet drain pipe 198.

In a preferred embodiment of the invention the PLC 201 executes instructions stored in program 170 that causes the apparatus 210 to operate according to the timing sequence that is illustrated in Figure 23 for actions such as filling and emptying the treatment tank with sterilizer and water, operating the grinder (shredder) and the conveyor.

USE FOR THE INVENTION The above description identifies at least one specific, substantial and credible use for the invention as a compact but efficient apparatus for grinding and sterilizing hazardous waste which uses less water.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term "comprises" and its variations, such as "comprising" and "comprised of' is used throughout in an inclusive sense and not to the exclusion of any additional features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention. Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.

Claims

The claims defining the invention are as follows:

1. An apparatus for treating medical waste, the apparatus comprising an inlet, a grinding assembly associated with the inlet to grind the waste, a treatment tank associated with the grinding assembly such that ground waste passes into the treatment tank, and a conveyor to convey treated waste from the treatment tank to an outlet.

2. The apparatus of claim 1, wherein the inlet comprises a hopper having an upper lid that can be opened and closed and a lower open area to enable waste to be conveyed to the grinding assembly.

3. The apparatus as claimed in claim 2, wherein the hopper is associated with a feed means to facilitate passage of the waste in the hopper towards the grinding assembly.

4. The apparatus of claim 3, wherein the feed means comprises a press plate which is hydraulically operable to push against the waste in the hopper.

5. The apparatus of claim 3 or claim 4, including at least one spray nozzle to assist with periodic washing out of the hopper and grinding assembly.

6. The apparatus as claimed in any one of the preceding claims, wherein the grinding assembly comprises a rotatable grinding roller and a fixed grinding plate between which the waste material passes and is ground.

7. The apparatus of claim 6, wherein the grinding roller has a side wall containing a multiplicity of projecting cutting teeth.

8. The apparatus of claim 7, wherein the teeth extend along the roller in longitudinal rows.

9. The apparatus of claim 8, wherein the teeth in one longitudinal row are offset relative to the teeth in an adjacent said longitudinal row.

10. The apparatus of any one of claims 6-9, wherein the fixed grinding plate includes a leading edge containing a multiplicity of recesses conforming to the projecting teeth on the grinding roller.

11. The apparatus as claimed in any one of the preceding claims, wherein the treatment tank is positioned below the grinding assembly such that ground waste falls into the treatment tank.

12. The apparatus of claim 11, wherein the treatment tank includes a lower collection area in which the ground waste can settle.

13. The apparatus as claimed in any one of the preceding claims, wherein the conveyor comprises an auger conveyor having a spiral auger within a tubular housing.

14. The apparatus of claim 13, wherein the conveyor is upwardly inclined such that conveying of the treated ground waste occurs along an upwardly inclined or an upward direction.

15. The apparatus of claim 13 or 14, wherein a lower end of the auger is able to collect ground waste from a lower collection area in the treatment tank.

16. The apparatus as claimed in any one of the preceding claims, wherein components of the apparatus are controlled by a controller.

17. The apparatus as claimed in any one of the preceding claims including at least one agitator for agitating ground waste with a liquid within the treatment tank.

18. The apparatus according to any of the preceding claims, wherein the treatment tank is located in place with quick release latches.

19. The apparatus according to any of the preceding claims wherein the treatment tank includes an observation window for viewing the interior of said tank.

20. A method for treating medical waste comprising grinding the waste material, contacting the waste material with an aqueous mixture containing disinfectant in a treatment tank and for a time sufficient to disinfect the ground waste material, draining off the liquid in the treatment tank, allowing the treated ground waste material to settle in a lower part of the treatment tank and conveying the treated ground waste material through an auger conveyor and along an upward inclination to an outlet.

21. A method according to claim 20, further including agitating the aqueous mixture with ground waste material in the treatment tank.